Bio

Clinical Focus


  • Cardiovascular Disease
  • Cardiology (Heart)

Academic Appointments


Professional Education


  • Board Certification: Echocardiography, National Board of Echocardiography (1998)
  • Fellowship:Stanford University School of Medicine (1981) CA
  • Residency:Stanford University School of Medicine (1980) CA
  • Internship:Seraphimer Hospital (1976) Sweden
  • Residency:Seraphimer Hospital (1978) Sweden
  • Fellowship:Stanford University School of Medicine (1977) CA
  • Board Certification: Cardiovascular Disease, American Board of Internal Medicine (1983)
  • Board Certification: Internal Medicine, American Board of Internal Medicine (1980)
  • Residency:University of Connecticut Health Center (1979) CT
  • Medical Education:Karolinska Institute (1975) Sweden

Research & Scholarship

Current Research and Scholarly Interests


My main research continues to be in the field of echocardiography. Several areas of research are currently being pursued:

1. Transesophageal echocardiography - Its value and limitation as a diagnostic and monitoring tool.

2. Exercise/stress echocardiography - A relatively new research area using echocardiography together with treadmill testing or with pharmacologic stress testing (such as dobutamine) to evaluate ischemia during stress.

3. Echocardiographic evaluation of LV wall motion and LV function - Several studies are ongoing, looking at left ventricular cardiac output calculated non-invasively.

Teaching

2013-14 Courses


Publications

Journal Articles


  • Race differences in ventricular remodeling and function among college football players. American journal of cardiology Haddad, F., Peter, S., Hulme, O., Liang, D., Schnittger, I., Puryear, J., Gomari, F. A., Finocchiaro, G., Myers, J., Froelicher, V., Garza, D., Ashley, E. A. 2013; 112 (1): 128-134

    Abstract

    Athletic training is associated with increases in ventricular mass and volume. Recent studies have shown that left ventricular mass increases proportionally in white athletes with a mass/volume ratio approaching unity. The objective of this study was to compare the proportionality in ventricular remodeling and ventricular function in black versus white National Collegiate Athletic Association Division I football players. From 2008 to 2011, football players at Stanford University underwent cardiovascular screening with a 12-point history and physical examination, electrocardiography, and focused echocardiography. Compared with white players, black players had on average higher left ventricular mass indexes (77 ± 11 vs 71 ± 11 g/m(2), p = 0.009), higher mass/volume ratios (1.18 ± 0.16 vs 1.06 ± 0.09 g/ml, p <0.001), and higher QRS vector magnitudes (3.2 ± 0.7 vs 2.7 ± 0.8, p = 0.002). Black race had an odds ratio of 14 (95% confidence interval 5 to 42, p <0.001) for a mass/volume ratio >1.2. Mass/volume ratio was inversely related to early diastolic tissue Doppler velocity e' (r = -0.50, p <0.001) but not to QRS vector magnitude (r = 0.065, p = 0.034). With regard to systolic indexes, there was no significant difference in the left ventricular ejection fraction, velocity of circumferential shortening, and isovolumic acceleration. In conclusion, black college football players exhibit more concentric ventricular remodeling, lower early diastolic annular velocities, and increased ventricular voltage compared with white players. Ventricular mass increases proportionally to volume in white players but not in black players.

    View details for DOI 10.1016/j.amjcard.2013.02.065

    View details for PubMedID 23602691

  • A novel stress echocardiography pattern for myocardial bridge with invasive structural and hemodynamic correlation. Journal of the American Heart Association Lin, S., Tremmel, J. A., Yamada, R., Rogers, I. S., Yong, C. M., Turcott, R., McConnell, M. V., Dash, R., Schnittger, I. 2013; 2 (2)

    Abstract

    Patients with a myocardial bridge (MB) and no significant obstructive coronary artery disease (CAD) may experience angina presumably from ischemia, but noninvasive assessment has been limited and the underlying mechanism poorly understood. This study seeks to correlate a novel exercise echocardiography (EE) finding for MBs with invasive structural and hemodynamic measurements.Eighteen patients with angina and an EE pattern of focal end-systolic to early-diastolic buckling in the septum with apical sparing were prospectively enrolled for invasive assessment. This included coronary angiography, left anterior descending artery (LAD) intravascular ultrasound (IVUS), and intracoronary pressure and Doppler measurements at rest and during dobutamine stress. All patients were found to have an LAD MB on IVUS. The ratios of diastolic intracoronary pressure divided by aortic pressure at rest (Pd/Pa) and during dobutamine stress (diastolic fractional flow reserve [dFFR]) and peak Doppler flow velocity recordings at rest and with stress were successfully performed in 14 patients. All had abnormal dFFR (?0.75) at stress within the bridge, distally or in both positions, and on average showed a more than doubling in peak Doppler flow velocity inside the MB at stress. Seventy-five percent of patients had normalization of dFFR distal to the MB, with partial pressure recovery and a decrease in peak Doppler flow velocity.A distinctive septal wall motion abnormality with apical sparing on EE is associated with a documented MB by IVUS and a decreased dFFR. We posit that the septal wall motion abnormality on EE is due to dynamic ischemia local to the compressed segment of the LAD from the increase in velocity and decrease in perfusion pressure, consistent with the Venturi effect.

    View details for DOI 10.1161/JAHA.113.000097

    View details for PubMedID 23591827

  • Clinical and Functional Correlates of Early Microvascular Dysfunction After Heart Transplantation CIRCULATION-HEART FAILURE Haddad, F., Khazanie, P., Deuse, T., Weisshaar, D., Zhou, J., Nam, C. W., Vu, T. A., Gomari, F. A., Skhiri, M., Simos, A., Schnittger, I., Vrotvec, B., Hunt, S. A., Fearon, W. F. 2012; 5 (6): 759-768

    Abstract

    Microvascular dysfunction is emerging as a strong predictor of outcome in heart transplant recipients. At this time, the determinants and consequences of early microvascular dysfunction are not well established. The objective of the study was to determine the risk factors and functional correlates associated with early microvascular dysfunction in heart transplant recipients.Sixty-three heart transplant recipients who had coronary physiology assessment, right heart catheterization, and echocardiography performed at the time of their first annual evaluation were included in the study. Microvascular dysfunction was assessed using the recently described index of microcirculatory resistance. The presence of microvascular dysfunction, predefined by an index of microcirculatory resistance >20, was observed in 46% of patients at 1 year. A history of acute rejection and undersized donor hearts were associated with microvascular dysfunction at 1 year, with odds ratio of 4.0 (1.3-12.8) and 3.6 (1.2-11.1), respectively. Patients with microvascular dysfunction had lower cardiac index (3.1±0.7 versus 3.5±0.7 L/min per m(2); P=0.02) and mild graft dysfunction measured by echocardiography-derived left and right myocardial performance indices ([0.54±0.09 versus 0.43±0.09; P<0.01] and [0.47±0.14 versus 0.32±0.05; P<0.01], respectively). Microvascular dysfunction was also associated with a higher likelihood of death, graft failure, or allograft vasculopathy at 5 years after transplant (hazard ratio, 2.52 [95% CI, 1.04-5.91]).A history of acute rejection during the first year and smaller donor hearts were identified as risk factors for early microvascular dysfunction. Microvascular dysfunction assessed using index of microcirculatory resistances at 1 year was also associated with worse graft function and possibly worse clinical outcomes.

    View details for DOI 10.1161/CIRCHEARTFAILURE.111.962787

    View details for Web of Science ID 000313580100023

    View details for PubMedID 22933526

  • Characteristics and Outcome After Hospitalization for Acute Right Heart Failure in Patients With Pulmonary Arterial Hypertension CIRCULATION-HEART FAILURE Haddad, F., Peterson, T., Fuh, E., Kudelko, K. T., Perez, V. D., Skhiri, M., Vagelos, R., Schnittger, I., Denault, A. Y., Rosenthal, D. N., Doyle, R. L., Zamanian, R. T. 2011; 4 (6): 692-699

    Abstract

    Although much is known about the risk factors for poor outcome in patients hospitalized with acute heart failure and left ventricular dysfunction, much less is known about the syndrome of acute heart failure primarily affecting the right ventricle (acute right heart failure).By using Stanford Hospital's pulmonary hypertension database, we identified consecutive acute right heart failure hospitalizations in patients with PAH. We used longitudinal regression analysis with the generalized estimating equations method to identify factors associated with an increased likelihood of 90-day mortality or urgent transplantation. From June 1999 to September 2009, 119 patients with PAH were hospitalized for acute right heart failure (207 episodes). Death or urgent transplantation occurred in 34 patients by 90 days of admission. Multivariable analysis identified a higher respiratory rate on admission (>20 breaths per minute; OR, 3.4; 95% CI, 1.5-7.8), renal dysfunction on admission (glomerular filtration rate <45 mL/min per 1.73 m2; OR, 2.7; 95% CI, 1.2-6.3), hyponatremia (serum sodium ?136 mEq/L; OR, 3.6; 95% CI, 1.7-7.9), and tricuspid regurgitation severity (OR, 2.5 per grade; 95% CI, 1.2-5.5) as independent factors associated with an increased likelihood of death or urgent transplantation.These results highlight the high mortality after hospitalizations for acute right heart failure in patients with PAH. Factors identifiable within hours of hospitalization may help predict the likelihood of death or the need for urgent transplantation in patients with PAH.

    View details for DOI 10.1161/CIRCHEARTFAILURE.110.949933

    View details for Web of Science ID 000297166100008

    View details for PubMedID 21908586

  • A comparison of echocardiographic measures of diastolic function for predicting all-cause mortality in a predominantly male population AMERICAN HEART JOURNAL Nguyen, P. K., Schnittger, I., Heidenreich, P. A. 2011; 161 (3): 530-537

    Abstract

    Prior studies demonstrating the prognostic value of echocardiographic measures of diastolic function have been limited by sample size, have included only select clinical populations, and have not incorporated newer measures of diastolic function nor determined their independent prognostic value. The objective of this study is to determine the independent prognostic value of established and new echocardiographic parameters of diastolic function.We included 3,604 consecutive patients referred to 1 of 3 echocardiography laboratories over a 2-year period. We obtained measurements of mitral inflow velocities, pulmonary vein filling pattern, mitral annulus motion (e'), and propagation velocity (V(p)). The primary end point was 1-year all-cause mortality.The mean age of the patients was 68 years, and 95% were male. There were 277 deaths during a mean follow-up of 248 ± 221 days. For patients with reduced left ventricular ejection fraction (LVEF), all measured parameters except for e' were associated with mortality (P < .05) on univariate analysis. For patients with preserved LVEF, the E-wave velocity was significantly associated with mortality (P < .05) on univariate analysis. The deceleration time/E-wave velocity ratio, V(p), and pulmonary vein filling pattern were borderline significant (P < .10). With multivariate analysis, only V(p) was associated with survival for both reduced (P = .02) and preserved LVEF groups (P = .01).In a large, clinically diverse population, most measures of diastolic function were predictive of all-cause mortality without adjustment for patient characteristics. On multivariate analysis, only V(p) was independently associated with total mortality. This association with mortality may be related to factors other than diastolic function and warrants further investigation.

    View details for DOI 10.1016/j.ahj.2010.12.010

    View details for Web of Science ID 000288156400018

    View details for PubMedID 21392608

  • Mechanisms of exercise intolerance in patients with hypertrophic cardiomyopathy AMERICAN HEART JOURNAL Le, V., Perez, M. V., Wheeler, M. T., Myers, J., Schnittger, I., Ashley, E. A. 2009; 158 (3): E27-E34

    Abstract

    To determine the relation between echocardiogram findings and exercise capacity in hypertrophic cardiomyopathy (HCM).Sixty-three patients (48 +/- 15 years) were referred for cardiopulmonary testing and exercise echocardiography. They were classified by morphology: proximal (n = 11), reverse curvature (n = 32), apical (n = 7), and concentric HCM (n = 13). There were more women in proximal and reverse curvature groups. Proximal HCM patients were older. Maximal left ventricular thickness was highest in reverse curvature group. At peak exercise, concentric HCM achieved the lowest percent predicted maximal Vo2. Excluding apical group, no significant differences in gradient were noted between groups. Overall, no statistically significant correlation was found between peak Vo2, wall thickness, and gradient. Significant correlations were noted between peak Vo2 and indexed left atrial (LA) volume (r = -0.52), lateral E' (r = 0.50), and lateral E/E' ratio (r = -0.46). A multivariate model including age, lateral E', indexed LA volume, and mitral A wave explained 46% of the variance in peak Vo2 (P = .01).Lateral E' and indexed LA volume are negatively correlated with functional capacity. Although patients with concentric morphology achieved the lowest peak Vo2, wall thickness and gradient did not predict exercise capacity.

    View details for DOI 10.1016/j.ahj.2009.06.006

    View details for Web of Science ID 000269641200027

    View details for PubMedID 19699847

  • Multiplanar Reconstruction of Three-Dimensional Transthoracic Echocardiography Improves the Presurgical Assessment of Mitral Prolapse JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY Beraud, A., Schnittger, I., Miller, D. C., Liang, D. H. 2009; 22 (8): 907-913

    Abstract

    The aim of this study was to evaluate the value and accuracy of multiplanar reconstruction (MPR) of three-dimensional (3D) transthoracic echocardiographic data sets in assessing mitral valve pathology in patients with surgical mitral valve prolapse (MVP).Sixty-four patients with surgical MVP and preoperative two-dimensional (2D) and 3D transthoracic echocardiography were analyzed. The descriptions obtained by 3D MPR and 2D were compared in the context of the surgical findings.Two-dimensional echocardiography correctly identified the prolapsing leaflets in 32 of 64 patients and 3D MPR in 46 of 64 patients (P=.016). Among the 27 patients with complex pathology (ie, more than isolated middle scallop of the posterior leaflet prolapse), 3D MPR identified 20 correctly, as opposed to 6 with 2D imaging (P<.001).Interpretation of 3D transthoracic echocardiographic images with MPR improved the accuracy of the description of the MVP compared with 2D interpretation. This added value of 3D MPR was most important in extensive and/or commissural prolapse.

    View details for DOI 10.1016/j.echo.2009.05.007

    View details for Web of Science ID 000268503400009

    View details for PubMedID 19553082

  • A Novel Non-Invasive Method of Estimating Pulmonary Vascular Resistance in Patients With Pulmonary Arterial Hypertension JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY Haddad, F., Zamanian, R., Beraud, A., Schnittger, I., Feinstein, J., Peterson, T., Yang, P., Doyle, R., Rosenthal, D. 2009; 22 (5): 523-529

    Abstract

    The assessment of pulmonary vascular resistance (PVR) plays an important role in the diagnosis and management of pulmonary arterial hypertension (PAH). The main objective of this study was to determine whether the noninvasive index of systolic pulmonary arterial pressure (SPAP) to heart rate (HR) times the right ventricular outflow tract time-velocity integral (TVI(RVOT)) (SPAP/[HR x TVI(RVOT)]) provides clinically useful estimations of PVR in PAH.Doppler echocardiography and right-heart catheterization were performed in 51 consecutive patients with established PAH. The ratio of SPAP/(HR x TVI(RVOT)) was then correlated with invasive indexed PVR (PVRI) using regression and Bland-Altman analysis. Using receiver operating characteristic curve analysis, a cutoff value for the Doppler equation was generated to identify patients with PVRI > or = 15 Wood units (WU)/m2.The mean pulmonary arterial pressure was 52 +/- 15 mm Hg, the mean cardiac index was 2.2 +/- 0.6 L/min/m2, and the mean PVRI was 20.5 +/- 9.6 WU/m2. The ratio of SPAP/(HR x TVI(RVOT)) correlated very well with invasive PVRI measurements (r = 0.860; 95% confidence interval, 0.759-0.920). A cutoff value of 0.076 provided well-balanced sensitivity (86%) and specificity (82%) to determine PVRI > 15 WU/m2. A cutoff value of 0.057 increased sensitivity to 97% and decreased specificity to 65%.The novel index of SPAP/(HR x TVI(RVOT)) provides useful estimations of PVRI in patients with PAH.

    View details for DOI 10.1016/j.echo.2009.01.021

    View details for Web of Science ID 000266091400017

    View details for PubMedID 19307098

  • An unusual case of partial anomalous pulmonary venous drainage: Utility of the cardiac MRI INTERNATIONAL JOURNAL OF CARDIOLOGY Kapoor, J. R., Katikireddy, C., Rubin, G., Schnittger, I., McConnell, M. V. 2009; 133 (1): E35-E36

    View details for DOI 10.1016/j.ijcard.2007.08.113

    View details for Web of Science ID 000263950100046

    View details for PubMedID 18164082

  • Predictive value of the index of microcirculatory resistance in patients with ST-segment elevation myocardial infarction JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Fearon, W. F., Shah, M., Ng, M., Brinton, T., Wilson, A., Trernmel, J. A., Schnittger, I., Lee, D. P., Vagelos, R. H., Fitzgerald, P. J., Yock, P. G., Yeung, A. C. 2008; 51 (5): 560-565

    Abstract

    The objective of this study is to evaluate the predictive value of the index of microcirculatory resistance (IMR) in patients undergoing primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI).Despite adequate epicardial artery reperfusion, a number of patients with STEMI have a poor prognosis because of microvascular damage. Assessing the status of the microvasculature in this setting remains challenging.In 29 patients after primary PCI for STEMI, IMR was measured with a pressure sensor/thermistor-tipped guidewire. The Thrombolysis In Myocardial Infarction (TIMI) myocardial perfusion grade, TIMI frame count, coronary flow reserve, and ST-segment resolution were also recorded.The IMR correlated significantly with the peak creatinine kinase (CK) (R = 0.61, p = 0.0005) while the other measures of microvascular dysfunction did not. In patients with an IMR greater than the median value of 32 U, the peak CK was significantly higher compared with those having values 32 U compared with

    View details for DOI 10.1016/j.jacc.2007.08.062

    View details for Web of Science ID 000252908600007

    View details for PubMedID 18237685

  • Multiplanar visualization in 3D transthoracic echocardiography for precise delineation of mitral valve pathology ECHOCARDIOGRAPHY-A JOURNAL OF CARDIOVASCULAR ULTRASOUND AND ALLIED TECHNIQUES Liang, D., Paloma, A., Kuppahally, S. S., Miller, D. C., Schnittger, I. 2008; 25 (1): 84-87

    Abstract

    A novel multiplanar reformatting (MPR) technique in three-dimensional transthoracic echocardiography (3D TTE) was used to precisely localize the prolapsed lateral segment of posterior mitral valve leaflet in a patient symptomatic with mitral valve prolapse (MVP) and moderate mitral regurgitation (MR) before undergoing mitral valve repair surgery. Transesophageal echocardiography was avoided based on the findings of this new technique by 3D TTE. It was noninvasive, quick, reproducible and reliable. Also, it did not need the time-consuming reconstruction of multiple cardiac images. Mitral valve repair surgery was subsequently performed based on the MPR findings and corroborated the findings from the MPR examination.

    View details for DOI 10.1111/j.1540-8175.2007.00566.x

    View details for Web of Science ID 000252206600013

    View details for PubMedID 18186784

  • Comparison of three-dimensional echocardiography to two-dimensional echocardiography and fluoroscopy for monitoring of endomyocardial biopsy AMERICAN JOURNAL OF CARDIOLOGY Amitai, M. E., Schnittger, I., Popp, R. L., Chow, J., Brown, P., Liang, D. H. 2007; 99 (6): 864-866

    Abstract

    Real-time 3-dimensional echocardiography (RT3DE) offers the rapid acquisition of quantitative and qualitative anatomic data without the use of geometric assumptions. This study was designed to test the feasibility and potential superiority of RT3DE versus 2-dimensional echocardiography (2DE) and standard fluoroscopy for monitoring endomyocardial biopsies (EMBs). Thirty-eight consecutive EMBs performed under fluoroscopic guidance in 26 patients were monitored using 2DE and RT3DE alternately. Two reviewers scored each biopsy pass for visualization of the tip of the bioptome and location of the actual biopsy. Overall image quality was noted as good or poor, and the effect of image quality on tip localization was analyzed. A total of 243 biopsy attempts were made during 38 EMBs. The location of the biopsy was determined in 74% of the biopsies monitored with RT3DE, whereas 2DE demonstrated the location with certainty in only 43% of the biopsies (p <0.0001). On a procedure-by-procedure comparison, RT3DE was found to show the bioptome tip better in 23 of 38 biopsies, compared with 1 of 38 for 2DE (p = 0.001). In 14 of 38 EMBs, neither method was clearly better. In conclusion, RT3DE improves the ability to see the location of the bioptome during EMB compared with 2DE and fluoroscopy.

    View details for DOI 10.1016/j.amjcard.2006.10.050

    View details for Web of Science ID 000245289200027

    View details for PubMedID 17350384

  • Clinical dilemmas in treating left ventricular thrombus. International journal of cardiology Leeper, N. J., Gupta, A., Schnittger, I., Wu, J. C. 2007; 114 (3): e118-9

    View details for PubMedID 17049652

  • Screening for coronary artery disease after mediastinal irradiation for Hodgkin's disease JOURNAL OF CLINICAL ONCOLOGY Heidenreich, P. A., Schnittger, I., Strauss, H. W., Vagelos, R. H., Lee, B. K., Mariscal, C. S., Tate, D. J., Horning, S. J., Hoppe, R. T., Hancock, S. L. 2007; 25 (1): 43-49

    Abstract

    Incidental cardiac irradiation during treatment of thoracic neoplasms has increased risks for subsequent acute myocardial infarction or sudden cardiac death. Identifying patients who have a high risk for a coronary event may decrease morbidity and mortality. The objective of this study was to evaluate whether stress imaging can identify severe, unsuspected coronary stenoses in patients who had prior mediastinal irradiation for Hodgkin's disease.We enrolled 294 outpatients observed at a tertiary care cancer treatment center after mediastinal irradiation doses 35 Gy for Hodgkin's disease who had no known ischemic cardiac disease. Patients underwent stress echocardiography and radionuclide perfusion imaging at one stress session. Coronary angiography was performed at the discretion of the physician.Among the 294 participants, 63 (21.4%) had abnormal ventricular images at rest, suggesting prior myocardial injury. During stress testing, 42 patients (14%) developed perfusion defects (n = 26), impaired wall motion (n = 8), or both abnormalities (n = 8). Coronary angiography showed stenosis 50% in 22 patients (55%), less than 50% in nine patients (22.5%), and no stenosis in nine patients (22.5%). Screening led to bypass graft surgery in seven patients. Twenty-three patients developed coronary events during a median of 6.5 years of follow-up, with 10 acute myocardial infarctions (two fatal).Stress-induced signs of ischemia and significant coronary artery disease are highly prevalent after mediastinal irradiation in young patients. Stress testing identifies asymptomatic individuals at high risk for acute myocardial infarction or sudden cardiac death.

    View details for DOI 10.1200/JCO.2006.07.0805

    View details for Web of Science ID 000243725900009

    View details for PubMedID 17194904

  • Diastolic dysfunction after mediastinal irradiation AMERICAN HEART JOURNAL Heidenreich, P. A., Hancock, S. L., Vagelos, R. H., Lee, B. K., Schnittger, I. 2005; 150 (5): 977-982

    Abstract

    Mediastinal irradiation is known to cause cardiac disease, but its effect on left ventricular diastolic function is unknown. The purpose of this study was to determine the prevalence of diastolic dysfunction and its association with prognosis in asymptomatic patients after mediastinal irradiation.We recruited 294 patients who had received at least 35 Gy to the mediastinum for treatment of Hodgkin disease. Each patient underwent resting echocardiography, stress echocardiography, and nuclear scintigraphy. Survival free from cardiac events was determined during 3.2 years of follow-up.The mean age of the included patients was 42 years, and 49% were male. Adequate measurements of diastolic function were obtained in 282 (97%) patients. Diastolic dysfunction was considered mild in 26 (9%) and moderate in 14 (5%). Exercise-induced ischemia was more common in patients with diastolic dysfunction (23%) than those with normal diastolic function (11%, P = .008). After adjustment for patient demographics, clinical characteristics, and radiation history, patients with diastolic dysfunction had worse event-free survival than patients with normal function (hazard ratio 1.66, 95% CI 1.06-2.4).There is a high prevalence of diastolic dysfunction in asymptomatic patients after mediastinal irradiation, and the presence of diastolic dysfunction is associated with stress-induced ischemia and a worse prognosis. Screening with Doppler echocardiography may be helpful in identifying patients at risk for subsequent cardiac events.

    View details for DOI 10.1016/j.ahj.2004.12.026

    View details for Web of Science ID 000233478800024

    View details for PubMedID 16290974

  • A systolic murmur is a common presentation of aortic regurgitation detected by echocardiography CLINICAL CARDIOLOGY Heidenreich, P. A., Schnittger, I., Hancock, S. L., Atwood, J. E. 2004; 27 (9): 502-506

    Abstract

    The finding of aortic regurgitation at a classical examination is a diastolic murmur.Aortic regurgitation is more likely to be associated with a systolic than with a diastolic murmur during routine screening by a noncardiologist physician.In all, 243 asymptomatic patients (mean age 42 +/- 10 years) with no known cardiac disease but at risk for aortic valve disease due to prior mediastinal irradiation (> or = 35 Gy) underwent auscultation by a noncardiologist followed by echocardiography. A systolic murmur was considered benign if it was grade < or = II/VI, not holosystolic, was not heard at the apex, did not radiate to the carotids, and was not associated with a diastolic murmur.Of the patients included, 122 (49%) were male, and 86 (35%) had aortic regurgitation, which was trace in 20 (8%), mild in 52 (21%), and moderate in 14 (6%). A systolic murmur was common in patients with aortic regurgitation, occurring in 12 (86%) with moderate, 26 (50%) with mild, 6 (30%) with trace, and 27 (17%) with no aortic regurgitation (p < 0.0001). The systolic murmurs were classified as benign in 21 (78%) patients with mild and 8 (67%) with moderate aortic regurgitation. Diastolic murmurs were rare, occurring in two (14%) with moderate, two (4%) with mild, and three (2%) with no aortic regurgitation (p=0.15).An isolated systolic murmur is a common auscultatory finding by a noncardiologist in patients with moderate or milder aortic regurgitation. A systolic murmur in patients at risk for aortic valve disease should prompt a more thorough physical examination for aortic regurgitation.

    View details for Web of Science ID 000223604300004

    View details for PubMedID 15471160

  • Asymptomatic cardiac disease following mediastinal irradiation JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Heidenreich, P. A., Hancock, S. L., Lee, B. K., Mariscal, C. S., Schnittger, I. 2003; 42 (4): 743-749

    Abstract

    This study was designed to evaluate the potential benefit of screening previously irradiated patients with echocardiography.Mediastinal irradiation is known to cause cardiac disease. However, the prevalence of asymptomatic cardiac disease and the potential for intervention before symptom development are unknown.We recruited 294 asymptomatic patients (mean age 42 +/- 9 years, 49% men, mean mantle irradiation dose 43 +/- 0.3 Gy) treated with at least 35 Gy to the mediastinum for Hodgkin's disease. After providing written consent, each patient underwent electrocardiography and transthoracic echocardiography. Valvular disease was common and increased with time following irradiation. Patients who had received irradiation more than 20 years before evaluation had significantly more mild or greater aortic regurgitation (60% vs. 4%, p < 0.0001), moderate or greater tricuspid regurgitation (4% vs. 0%, p = 0.06), and aortic stenosis (16% vs. 0%, p = 0.0008) than those who had received irradiation within 10 years. The number needed to screen to detect one candidate for endocarditis prophylaxis was 13 (95% confidence interval [CI] 7 to 44) for patients treated within 10 years and 1.6 (95% CI 1.3 to 1.9) for those treated at least 20 years ago. Compared with the Framingham Heart Study population, mildly reduced left ventricular fractional shortening (<30%) was more common (36% vs. 3%), and age- and gender-adjusted left ventricular mass was lower (90 +/- 27 g/m vs. 117 g/m) in irradiated patients.There is a high prevalence of asymptomatic heart disease in general, and aortic valvular disease in particular, following mediastinal irradiation. Screening echocardiography should be considered for patients with a history of mediastinal irradiation.

    View details for DOI 10.1016/S0735-1097(03)00759-9

    View details for Web of Science ID 000184780600027

    View details for PubMedID 12932613

  • Accuracy of hand-carried ultrasound ECHOCARDIOGRAPHY-A JOURNAL OF CARDIOVASCULAR ULTRASOUND AND ALLIED TECHNIQUES Liang, D., Schnittger, I. 2003; 20 (5): 487-490

    Abstract

    Hand-carried ultrasound introduces a new group of devices, operators and usage patterns to echocardiography. This may have significant impact on the accuracy of the findings obtained with hand-carried ultrasound. Although reasonable agreement can be obtained with standard echocardiography in certain circumstances, limitations in imaging modes, device image quality, operator experience, and study completeness may significantly limit the diagnostic accuracy of hand carried ultrasound. Despite this, hand-carried ultrasound has the potential to improve significantly upon the data obtained by physical examination.

    View details for Web of Science ID 000183844800015

    View details for PubMedID 12848872

  • Clinical use of cardiac ultrasound performed with a hand-carried device in patients admitted for acute cardiac care AMERICAN JOURNAL OF CARDIOLOGY Rugolotto, M., CHANG, C. P., Hu, B., Schnittger, I., Liang, D. H. 2002; 90 (9): 1040-?

    View details for Web of Science ID 000178991100033

    View details for PubMedID 12398985

  • Rapid assessment of cardiac anatomy and function with a new hand-carried ultrasound device (OptiGo): a comparison with standard echocardiography. European journal of echocardiography Rugolotto, M., Hu, B. S., Liang, D. H., Schnittger, I. 2001; 2 (4): 262-269

    Abstract

    The aim of this study was to evaluate image quality and accuracy of a new hand-carried ultrasound device, OptiGo (Agilent Technologies) when compared to standard echocardiography in the setting of a focused examination in the assessment of cardiac anatomy and function.One-hundred and twenty-one patients were prospectively enrolled. Image quality and accuracy in assessment of chamber sizes, left ventricular (LV) wall thickness and contractility, right ventricular (RV) function, mitral and aortic leaflet thickening, mitral annular calcification, pericardial effusion and valvular regurgitation were assessed. Two-dimensional (2D) findings were graded on a four-point scale, except for LV function (six-point) and valvular leaflet opening (two-point). Colour Doppler assessment of valvular regurgitation was graded on a seven-point scale. A one-point difference was considered minor; a two or more point difference was considered major. There was no statistically significant difference in image quality between the two devices. For 2D data, the number of total (minor and major) differences between the hand-carried and standard echocardiograph examinations was significantly greater than the inter-observer variability (14.3% vs 10.7%, P< 0.05), however, major differences alone were not statistically different. For the colour Doppler assessment of regurgitation there was a significant difference between the devices for total (minor and major) differences, (40.0% vs 31.8%,P < 0.007) however, the number of major differences is explained by inter-observer variability.Image quality and diagnostic accuracy of the hand-carried device, OptiGo, was adequate for the purpose of performing a focused assessment of a limited number of 2D and Doppler parameters for the evaluation of cardiac anatomy and function.

    View details for PubMedID 11888820

  • Contrast echocardiography is superior to tissue harmonics for assessment of left ventricular function in mechanically ventilated patients AMERICAN HEART JOURNAL Kornbluth, M., Liang, D. H., BROWN, P., Gessford, E., Schnittger, I. 2000; 140 (2): 291-296

    Abstract

    Assessment of left ventricular function by echocardiography is frequently challenging in mechanically ventilated patients. We evaluated the potential value of contrast-enhanced imaging and tissue harmonic imaging over standard fundamental imaging for endocardial border detection (EBD) in these patients.Fifty patients underwent standard transthoracic 2D echocardiography and were imaged in fundamental and tissue harmonic modes and subsequently with intravenous contrast (Optison). Two echocardiographers reviewed all studies for ease of visualization of endocardial border segments and scoring of wall motion. EBD for each wall segment was graded from 1 to 4 (1 = excellent EBD). Wall motion was scored by a standard 16-segment model and 1 to 5 scale. Studies were categorized as nondiagnostic if 4 of 6 segments in the apical 4-chamber view were either poorly seen or not seen (EBD score 3 or 4). Quantification of ejection fraction was independently performed offline. Visualization of 68% of all segments improved with contrast echocardiography versus 17% improvement with tissue harmonics compared with fundamental mode. Significant improvement (poor/not seen to good/excellent) occurred in 60% of segments with contrast echocardiography versus 18% with tissue harmonics. A total of 850 segments were deemed poor/not seen, 78% of which improved to good/excellent with contrast echocardiography versus 23% with tissue harmonics. Interobserver agreement on EBD was 64% to 70%. Conversion of nondiagnostic to diagnostic studies occurred in 85% of patients with contrast echocardiography versus 15% of patients with tissue harmonics. Scoring of wall motion with fundamental mode, tissue harmonics, and contrast echocardiography was possible in 61%, 74%, and 95% of individual segments, respectively (P <.001). Wall motion scoring was altered in 17% of segments with contrast echocardiography and in 8% with tissue harmonics. Interobserver agreement on wall motion scoring was 84% to 88%. Contrast echocardiography permitted measurement of ejection fraction 45% (P =.003) more often over fundamental mode versus a 27% (P =.09) increase with tissue harmonics.Contrast echocardiography is superior to tissue harmonic imaging for EBD, wall motion scoring, and quantification of ejection fraction in mechanically ventilated patients.

    View details for Web of Science ID 000088739900018

    View details for PubMedID 10925345

  • Clinical outcome in the Marfan syndrome with ascending aortic dilatation followed annually by echocardiography AMERICAN JOURNAL OF CARDIOLOGY Kornbluth, M., Schnittger, I., Eyngorina, I., Gasner, C., Liang, D. H. 1999; 84 (6): 753-?

    Abstract

    This study reviewed the utility of echocardiography in following patients with the Marfan syndrome for whom cardiovascular complications, especially aortic root dilatation, dissection and rupture, are the major causes of morbidity and mortality. We conclude that echocardiography can be used to follow asymptomatic patients with the Marfan syndrome.

    View details for Web of Science ID 000082536100027

    View details for PubMedID 10498154

  • Native tissue harmonic imaging improves endocardial border definition and visualization of cardiac structures JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY Kornbluth, M., Liang, D. H., Paloma, A., Schnittger, I. 1998; 11 (7): 693-701

    Abstract

    The purpose of this study was to examine the impact of native tissue harmonic imaging on endocardial border definition, wall motion scoring, and visualization of intracardiac structures.For wall motion analysis, 60 consecutive patients underwent standard transthoracic echocardiograms in both harmonic and fundamental modes. Three experienced echocardiographers reviewed each echocardiogram. Endocardial border definition for each wall segment was graded from 1 to 4 (1 = excellent endocardial definition). Wall motion was scored by using a standard 16-segment model and 1 to 5 scale. For visualization of cardiac structures, 50 consecutive patients were studied. Two experienced interpreters reviewed each echocardiogram for both normal and abnormal structures by using the following scoring scale: (1) harmonic is much better than fundamental, (2) harmonic is slightly better than fundamental, (3) harmonic and fundamental are equivalent, (4) fundamental is slightly better than harmonic, and (5) fundamental is much better than harmonic. Visualization of 64% (95% confidence interval [CI] 0.61 to 0.66) of all segments improved in harmonic mode, with 26% (95% CI 0.24 to 0.29) improving from poor/not seen to good/excellent. Of 444 segments deemed poor/not seen, visualization of 312 (70%) (95% CI 0.66 to 0.75) improved to good/excellent with harmonic mode. Of these 312 segments, 55% comprised the lateral and anterior walls on apical views. Interobserver agreement on endocardial border definition was 82% to 86%. Scoring of wall motion was altered in 171 of 1075 (16%) of segments by harmonic mode. This was significantly greater than the interobserver disagreement, which was only 10% (p<0.002). Mitral valve chordae and papillary muscles were visualized slightly/much better with harmonic mode in 40 of 50 echocardiograms. Left atrial boundaries were seen slightly/much better in harmonic mode in 29 of 50 studies. Abnormal structures were seen slightly/much better in harmonic mode in 12 of 14 cases.Native tissue harmonic imaging has significant impact on endocardial border definition and wall motion scoring and improves the visualization of both normal and abnormal cardiac structures.

    View details for Web of Science ID 000074885200003

    View details for PubMedID 9692526

  • Automatic cardiac output measurement (ACOM): Clinical applications of a new noninvasive tool INTERNATIONAL JOURNAL OF CARDIAC IMAGING Trindade, P. T., BROWN, P., Puryear, J. V., Popylisen, S., Schnittger, I. 1998; 14 (3): 147-154

    Abstract

    This study sought to validate a new noninvasive method to measure cardiac output, in the clinical setting, using color Doppler flow integration. This method, the automatic cardiac output measurement (ACOM), using color Doppler was recently developed and validated in vitro. ACOM was performed at the aortic valve and in the left ventricular outflow tract in 106 subjects (60 men, mean age 52 +/- 18) and compared with the echocardiographic pulsed-wave Doppler and a 2-D volume method. In 14 patients the noninvasive methods were correlated with the thermodilution technique. ACOM was feasible in 101 subjects (95%). The correlation factor between the values obtained with ACOM in the apical 5-chamber view and apical long-axis view was 0.75 at the aortic valve and 0.74 in the left ventricular outflow tract. Interoperator variability for ACOM in the apical 5-chamber and apical long-axis views were 0.93 and 0.75, respectively. The best comparison of ACOM with the pulsed-wave echo-Doppler technique occurred in the apical long-axis view (n = 79, r = 0.62), whereas the correlation with the 2-D volume method was poor. The most favorable comparison of ACOM with the thermodilution technique (n = 14) was also obtained in the apical long-axis view (5.408 +/- 1.72 vs. 3.356 +/- 1.281/min. [mean +/- SD], r = 0.71). Assuming the thermodilution technique as 'gold standard', the pulsed-wave echo-Doppler technique showed a better correlation (5.408 +/- 1.72 vs. 4.664 +/- 1.281/min., r = 0.84). ACOM is a useful, reproducible, noninvasive tool for rapid automated measurements of cardiac output. There is, however, an underestimation when compared with the pulsed-wave Doppler echocardiography and the thermodilution techniques. Good 2-D echocardiographic images, adequate color filling of the outflow tract and high frame rates are prerequisites for accurate values. Further refinements of this new technique are needed to enhance its clinical value in the future.

    View details for Web of Science ID 000076691200002

    View details for PubMedID 9813750

  • Assessment of left ventricular wall motion abnormalities with the use of color kinesis: A valuable visual and training aid JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY Lau, Y. S., Puryear, J. V., Gan, S. C., Fowler, M. B., Vagelos, R. H., Popp, R. L., Schnittger, I. 1997; 10 (6): 665-672

    Abstract

    Accurate interpretation of left ventricular segmental wall motion by echocardiography is an important yet difficult skill to learn. Color-coded left ventricular wall motion (color kinesis) is a tool that potentially could aid in the interpretation and provide semiquantification. We studied the usefulness of color kinesis in 42 patients with a history of congestive cardiomyopathy who underwent two-dimensional echocardiograms and a color kinesis study. The expert's reading of the two-dimensional wall motion served as a reference for comparison of color kinesis studies interpreted by the expert and a cardiovascular trainee. Correlation between two-dimensional echocardiography and the expert's and trainee's color coded wall motion scores were r = 0.83 and r = 0.67, respectively. Reproducibility between reviewers and between operators was also assessed. Interobserver variability for color-coded wall motion showed a correlation of r = 0.78. Correlation between operators was also good; r = 0.84. Color kinesis is reliable and appears promising as an adjunct in the assessment of wall motion abnormalities by echocardiography. It is both a valuable visual aid, as well as a training aid for the cardiovascular trainee.

    View details for Web of Science ID A1997XR35200011

    View details for PubMedID 9282356

  • Accuracy of biplane and multiplane transesophageal echocardiography in diagnosis of typical acute aortic dissection and intramural hematoma JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Keren, A., Kim, C. B., Hu, B. S., Eyngorina, I., Billingham, M. E., Mitchell, R. S., Miller, D. C., Popp, R. L., Schnittger, I. 1996; 28 (3): 627-636

    Abstract

    The purpose of this study was to evaluate the diagnostic accuracy of biplane and multiplane transesophageal echocardiography in patients with suspected aortic dissection, including intramural hematoma.Transesophageal echocardiography is a useful technique for rapid bedside evaluation of patients with suspected acute aortic dissection. The sensitivity of transesophageal echocardiography is high, but the diagnostic accuracy of biplane and multiplane transesophageal echocardiography for dissection and intramural hematoma is less well defined.We studied 112 consecutive patients at a major referral center who had undergone biplane or multiplane transesophageal echocardiography to identify aortic dissection. The presence, absence and type of aortic dissection (type A or B, typical dissection or intramural hematoma) were confirmed by operation or autopsy in 60 patients and by other imaging techniques in all. The accuracy of transesophageal echocardiography for ancillary findings of aortic dissection (intimal flap, fenestration and thrombosis) was assessed in the 60 patients with available surgical data.Of the 112 patients, aortic dissection was present in 49 (44%); 10 of these had intramural hematoma (5 with and 5 without involvement of the ascending aorta). Of the remaining 63 patients without dissection, 33 (29%) had aortic aneurysm and 30 (27%) had neither dissection nor aneurysm. The overall sensitivity and specificity of transesophageal echocardiography for the presence of dissection were 98% and 95%, respectively. The specificity for type A and type B dissection was 97% and 99%, respectively. The sensitivity and specificity for intramural hematoma was 90% and 99%, respectively. The accuracy of transesophageal echocardiography for diagnosis of acute significant aortic regurgitation and pericardial tamponade was 100%.Biplane and multiplane transesophageal echocardiography are highly accurate for prospective identification of the presence and site of aortic dissection, its ancillary findings and major complications in a large series of patients with varied aortic pathology. Intramural hematoma carries a high complication rate and should be treated identically with aortic dissection.

    View details for Web of Science ID A1996VE27300013

    View details for PubMedID 8772749

  • Wegener's granulomatosis presenting as dilated cardiomyopathy WESTERN JOURNAL OF MEDICINE Day, J. D., Ellison, K. E., Schnittger, I., Perlroth, M. G. 1996; 165 (1-2): 64-66

    View details for Web of Science ID A1996VG80200018

    View details for PubMedID 8855696

  • Upper airway resistance syndrome, nocturnal blood pressure monitoring, and borderline hypertension CHEST Guilleminault, C., Stoohs, R., Shiomi, T., Kushida, C., Schnittger, I. 1996; 109 (4): 901-908

    Abstract

    Upper airway resistance syndrome (UARS) is a sleep-disordered breathing syndrome characterized by complaints of daytime fatigue and/or sleepiness, increased upper airway resistance during sleep, frequent transient arousals, and no significant hypoxemia. Of a population of 110 subjects (58 men) diagnosed as having UARS, we investigated acute systolic and diastolic BP changes seen during sleep in two different samples. First, six patients from the original subject pool were found to have untreated chronic borderline high BP, and were subjected to 48 h of continuous ambulatory BP monitoring before treatment and another 48 h of BP monitoring 1 month after the start of nasal-continuous positive airway pressure (N-CPAP) treatment. Five of six subjects used their equipment on a regular basis and had their chronic borderline high BP completely controlled. No change in BP values was seen in the last subject, who discontinued N-CPAP after 3 days. A second protocol investigated seven normotensive subjects drawn from the initial subject pool. Continuous radial artery BP recording was performed during nocturnal sleep with simultaneous polygraphic recording of sleep/wake variables and respiration. BP changes were studied during periods of increased respiratory efforts and at the time of alpha EEG arousals. Increases in systolic and diastolic BP were noted during the breaths with the greatest inspiratory efforts without significant hypoxemia. A further increase in BP was noted in association with arousals. Three of these subjects also underwent echocardiography during sleep, which demonstrated a leftward shift of the interventricular septum with pulsus paradoxus in association with peak end-inspiratory esophageal pressure more negative than -35 cm H2O. Our study indicates that, in the absence of classic apneas, hypopneas, and repetitive significant drops in oxygen saturation (below 90%), repetitive increases in BP can occur as a result of increased airway resistance during sleep. It also shows that, in some patients with both UARS and borderline high BP, high BP can be controlled with treatment of UARS. We conclude that abnormal upper airway resistance during sleep, often associated with snoring, can play a role in the development of hypertension.

    View details for Web of Science ID A1996UE72400014

    View details for PubMedID 8635368

  • Valvular Strands. Cardiogenic Embolism. Baltimore:Williams & Wilkins, Schnittger I. 1996: 129-135
  • VALUE OF TRANSESOPHAGEAL ECHOCARDIOGRAPHY BEFORE DC CARDIOVERSION IN PATIENTS WITH ATRIAL-FIBRILLATION - ASSESSMENT OF EMBOLIC RISK BRITISH HEART JOURNAL Schnittger, I. 1995; 73 (4): 306-309

    View details for Web of Science ID A1995QU53500004

    View details for PubMedID 7756062

  • EPIDURAL AIR INJECTION ASSESSED BY TRANSESOPHAGEAL ECHOCARDIOGRAPHY REGIONAL ANESTHESIA Jaffe, R. A., Siegel, L. C., Schnittger, L., PROPST, J. W., BROCKUTNE, J. G. 1995; 20 (2): 152-155

    Abstract

    The object of this study, using transesophageal echocardiography (TEE) in anesthetized patients, was to investigate the occurrence of venous air embolism (VAE) when air is injected into the epidural space.Six patients between the ages of 18 and 50 years (ASA I-II) undergoing general anesthesia in a supine position for nonthoracic surgical procedures were studied. Prior to general anesthesia, an epidural catheter was placed into the epidural space using a Tuohy needle and a standard saline loss-of-resistance technique. Following verification of proper catheter placement, general anesthesia was induced and the trachea intubated. Thereafter, a TEE probe was inserted into the esophagus. After a 10-minute control period, and during continuous TEE videotape recording, 5 mL of air was rapidly injected into the epidural space through the epidural catheter. This was followed 10 minutes later by the epidural injection of 5 mL of room-temperature preservative-free saline. Microbubble echo targets were quantified in a range from 0 to 4+.Venous air microbubble emboli appeared in the circulation within 15 seconds after injecting either air or saline into the epidural space.No evidence of clinically significant VAE was seen in any patient. The results suggest that drugs injected into the epidural space may have unexpectedly easy access to the venous circulation with a potential to produce unwanted systemic effects. Clinicians should be alert to the possibility that local anesthetics, or any other drug placed epidurally, may rapidly enter the systemic circulation even without the intravenous placement of an epidural catheter.

    View details for Web of Science ID A1995QP69300012

    View details for PubMedID 7605763

  • On-line estimation of cardiac output with a new automated border detection system using transesophageal echocardiography: a preliminary comparison with thermodilution. Journal of cardiothoracic and vascular anesthesia Pinto, F. J., Siegel, L. C., Chenzbraun, A., Schnittger, I. 1994; 8 (6): 625-630

    Abstract

    Continuous estimation of cardiac output would be extremely useful for hemodynamic monitoring of patients in the operating room and intensive care settings. A recently developed echocardiographic imaging system provides real-time automated border detection (ABD) with the ability to measure cyclic changes in cavity area, and thus calculate changes in intracavitary volumes. Eight patients undergoing cardiac surgery were studied with intraoperative transesophageal (TEE), and cardiac outputs obtained with this new imaging system were compared with thermodilution (TD). Triplicate measurements were obtained simultaneously at five intraoperative times, three before and two after cardiopulmonary bypass. The 91 of 120 measurements with adequate TEE and TD data were analyzed. The average difference between the two techniques (bias) was -0.2 +/- 1.3 L/min. The limits of agreement (bias +/- 2 SD) were -2.8 L/min to 2.4 L/min. The average of the absolute value of the difference between measurements made with the two techniques was 0.9 +/- 0.8 L/min. Linear regression yielded the equation: ABD = 0.64TD + 1.57 L/min (r = 0.71). The average difference between the two techniques (bias) for detecting changes in cardiac output between sequential intraoperative times was 0.1 +/- 1.1 L/min. With further development, this new method shows promise for measurement of cardiac output in selected patient care settings.

    View details for PubMedID 7880989

  • TRANSESOPHAGEAL ECHOCARDIOGRAPHY IN THE INTENSIVE-CARE UNIT - IMPACT ON DIAGNOSIS AND DECISION-MAKING CLINICAL CARDIOLOGY Chenzbraun, A., Pinto, F. J., Schnittger, I. 1994; 17 (8): 438-444

    Abstract

    Transesophageal echocardiography (TEE) is widely used in the management of patients in intensive care units. The present study assesses the specific value of this technique in various categories of these patients. We reviewed 113 studies performed in 100 such patients for: suspected aortic dissection (25), suspected endocarditis (33), source of emboli assessment (19), hemodynamic instability (15), and miscellaneous (21). TEE provided diagnostic information in all patients with aortic dissection, in 53% of the cases with hemodynamic instability, in 50% of the cases with septic states with high likelihood of endocarditis, and in 29% of the cases where the question was the source of emboli. When the clinical probability for endocarditis was low, all transesophageal echocardiograms performed in septic patients were negative. The information provided by TEE was considered crucial in one-third of the positive cases; in about one-half of these special cases, the results were instrumental for further surgical management. There were no significant side effects related to the procedure. TEE is easily performed in the intensive care unit setting and yields useful information in almost half of the cases. Special benefit is expected in suspected aortic disease, hemodynamic instability, suspected endocarditis, and embolic events. The overall yield as screening procedure in febrile patients is low.

    View details for Web of Science ID A1994NZ09500006

    View details for PubMedID 7955591

  • EXERCISE ECHOCARDIOGRAPHY IN HEAT TRANSPLANT RECIPIENTS - A COMPARISON WITH ANGIOGRAPHY AND INTRACORONARY ULTRASONOGRAPHY JOURNAL OF HEART AND LUNG TRANSPLANTATION COLLINGS, C. A., Pinto, F. J., Valantine, H. A., Popylisen, S., Puryear, J. V., Schnittger, I. 1994; 13 (4): 604-613

    Abstract

    Transplant coronary artery disease is the leading cause of allograft failure in heart transplant recipients surviving beyond 1 year. Coronary angiography still remains the major technique for surveillance of these patients, with recent use of intracoronary ultrasonography to detect the early stages of intimal thickening. We evaluated exercise echocardiography to screen for the presence or absence of angiographic evidence of transplant coronary artery disease in any vessel, defined as follows: absent; stenosis 39% or less = mild; stenosis 40% to 69% = moderate; or stenosis > or = 70%, or more = severe. Fifty-one consecutive heart transplant recipients undergoing routine annual evaluation were included in the study. Of thirty-seven patients with no coronary artery disease, thirty-two had a normal and five had an abnormal exercise echocardiogram. Fourteen patients (27%) had transplant coronary artery disease by angiographic criteria; six had mild, six had moderate, and two had severe stenosis. One patient with mild and the two patients with severe transplant coronary artery disease had abnormal exercise echocardiograms. None of the patients with moderate disease had an abnormal exercise echocardiogram (false negative). Of forty-three patients with no or mild stenosis, 19 patients had moderate to severe intimal proliferation as seen with intracoronary ultrasonography. Of eight patients with moderate or severe stenosis, four were tested with intracoronary ultrasonography and all had moderate to severe intimal proliferation. Six patients had a "false positive" exercise echocardiogram, and of four who were tested with intracoronary ultrasonography, two had mild and two had moderate to severe intimal thickening. In summary, exercise echocardiography correctly excluded the presence of transplant coronary artery disease in 86% of patients but was associated with a high false negative rate for detection of moderate coronary stenosis. A false positive exercise echocardiogram was associated with intimal proliferation by intracoronary ultrasonography in several patients and suggests that coronary angiography may underestimate significant coronary artery disease.

    View details for Web of Science ID A1994PA31000005

    View details for PubMedID 7947876

  • FILLING PATTERNS IN LEFT-VENTRICULAR HYPERTROPHY - A COMBINED ACOUSTIC QUANTIFICATION AND DOPPLER STUDY JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Chenzbraun, A., Pinto, F. J., Popylisen, S., Schnittger, I., Popp, R. L. 1994; 23 (5): 1179-1185

    Abstract

    The purpose of this study was to evaluate the potential of acoustic quantification compared with Doppler echocardiography for assessment of left ventricular diastolic dysfunction.Diastolic dysfunction usually accompanies left ventricular hypertrophy. Although Doppler echocardiography is widely used, it has known limitations in the diagnosis of diastolic abnormalities. The ventricular area-change waveform obtained with acoustic quantification technology may provide an alternative to assess diastolic dysfunction.Potential acoustic quantification variables (peak rate of area change and mean slope of area change rate during rapid filling, amount of relative area change during rapid filling and atrial contraction) were obtained and compared with widely used Doppler indexes of ventricular filling (isovolumetric relaxation time, pressure half-time, peak early diastolic velocity/peak late diastolic velocity ratio, rapid filling, atrial contribution to filling) in 16 healthy volunteers and 30 patients with left ventricular hypertrophy.Criteria for abnormal relaxation were present in 68% of patients by acoustic quantification and in 64% of patients by Doppler echocardiography. However, abnormal relaxation was identified in 80% of patients by one or both methods. Acoustic quantification indicated abnormal relaxation in the presence of completely normalized Doppler patterns and in patients with mitral regurgitation or abnormal rhythm with unreliable Doppler patterns.Acoustic quantification potentially presents a new way to assess diastolic dysfunction. This technique may be regarded as complementary to Doppler echocardiography. The combined use of the methods may improve the diagnosis of left ventricular relaxation abnormalities.

    View details for Web of Science ID A1994PH37100028

    View details for PubMedID 8144786

  • COMPARISON OF ACOUSTIC QUANTIFICATION AND DOPPLER-ECHOCARDIOGRAPHY IN ASSESSMENT OF LEFT-VENTRICULAR DIASTOLIC VARIABLES BRITISH HEART JOURNAL Chenzbraun, A., Pinto, F. J., Popylisen, S., Schnittger, I., Popp, R. L. 1993; 70 (5): 448-456

    Abstract

    To assess the haemodynamic correlations of the waveforms of left ventricular area change obtained by automated boundary detection with newly developed acoustic quantification technology.The timing of events in the cardiac cycle was identified on the wave-form automated boundary detection and was correlated with the corresponding timing derived from pulsed wave Doppler flow velocity traces of the mitral valve and left ventricular outflow tract. The amounts of area change during the rapid filling phase and during atrial contraction were correlated with the time-velocity integrals of early and late diastolic ventricular filling obtained from Doppler tracings of the mitral inflow.A university medical school echocardiography laboratory.16 healthy volunteers and 19 patients referred for echocardiographic studies.A significant correlation was found between the methods for measurement of the time from the R wave to mitral valve opening (r = 0.72, p < 0.01), isovolumic relaxation time (r = 0.62, p < 0.01), and ejection time (r = 0.54, p < 0.01). The change of total area that occurred during rapid filling and atrial filling phases measured from the acoustic waveform correlated with the time-velocity integrals of the early and late diastolic mitral valve inflow velocity derived from Doppler echocardiography (r = 0.60 and r = 0.80, respectively).The waveform of left ventricular area obtained by the automated boundary detection technique identifies the phases of the cardiac cycle and correlates with Doppler values of left ventricular diastolic function. Therefore, this new method of automated boundary detection has potential uses in the assessment of left ventricular diastolic function.

    View details for Web of Science ID A1993MF26800012

    View details for PubMedID 8260277

  • SEGMENTAL WALL-MOTION ABNORMALITIES IN PATIENTS UNDERGOING TOTAL HIP-REPLACEMENT - CORRELATIONS WITH INTRAOPERATIVE EVENTS ANESTHESIA AND ANALGESIA PROPST, J. W., Siegel, L. C., Schnittger, I., FOPPIANO, L., Goodman, S. B., BROCKUTNE, J. G. 1993; 77 (4): 743-749

    Abstract

    We examined the effect of methylmethacrylate cement on venous embolization and cardiac function in 20 patients having total hip arthroplasty under general anesthesia. Segmental wall motion abnormalities and intracardiac targets (presumably emboli) were investigated by making videotaped recordings of the transgastric short axis and longitudinal 4-chamber views of the heart with transesophageal echocardiography at different points during surgery. The incidence of segmental wall motion abnormalities was the most frequent during insertion of cemented femoral prostheses (8 of 14 patients had wall motion abnormalities). This was significantly different from baseline measurements taken at the beginning of surgery (P < 0.05). In addition, there were also significantly more segmental wall motion abnormalities in patients having a cemented femoral component compared to those having an uncemented femoral prosthesis (P < 0.05). The incidence of wall motion abnormalities during acetabular and femoral reaming and during wound closure was not significantly different from baseline. Intracardiac targets (emboli) were seen in all 20 patients during surgery. The largest number of emboli occurred during reaming of the femur and during insertion of the femoral prosthesis. Significantly more emboli were seen with cemented components (P < 0.02). Most emboli were small (< 2 mm) and appeared similar to the microbubbles produced by agitating saline with a small amount of air. Six patients also had larger (> 5 mm) emboli that appeared to be solid material. One patent foramen ovale was detected (5% incidence). There were no adverse cardiac or neurologic events, and heart rate and arterial blood pressure remained within normal limits throughout surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

    View details for Web of Science ID A1993MA35700015

    View details for PubMedID 8214658

  • OBSTRUCTED BREATHING IN CHILDREN DURING SLEEP MONITORED BY ECHOCARDIOGRAPHY ACTA PAEDIATRICA Shiomi, T., Guilleminault, C., Stoohs, R., Schnittger, I. 1993; 82 (10): 863-871

    Abstract

    Six 3 to 14-year-old boys with snoring and obstructive sleep apnea syndrome were monitored polygraphically during sleep with and without nasal continuous positive airway pressure with simultaneous recording of esophageal pressure (Pes) and M-mode and two-dimensional echocardiograms. Continuous non-invasive blood pressure monitoring was performed in two older children. Three of the six children demonstrated a diastolic leftward shift of the interventricular septum related to the negativity of Pes. Progressively more negative Pes correlated significantly with an increase in right ventricular internal end-diastolic dimension and a decrease in left ventricular internal end-diastolic dimension, with at times left ventricular "collapse". One of the subjects with blood pressure monitoring demonstrated pulsus paradoxus with leftward shift of the interventricular septum. Nasal continuous positive airway pressure normalized all changes. Pulsus paradoxus and leftward shift of the interventricular septum are related to the mechanical changes associated with heavy snoring during sleep, regardless of the amount of oxygen desaturation.

    View details for Web of Science ID A1993MA60200015

    View details for PubMedID 8241648

  • Biplane transesophageal echocardiography in the diagnosis of patent foramen ovale. Journal of the American Society of Echocardiography Chenzbraun, A., Pinto, F. J., Schnittger, I. 1993; 6 (4): 417-421

    Abstract

    Patent foramen ovale is associated with unexplained systemic embolic events or persistent hypoxemia. The diagnosis of a patient foramen ovale is based on the existence of an interatrial right-to-left shunt. Biplane transesophageal echocardiography with its increased ability to provide accurate anatomic detail may allow the visualization of the actual opening of the patent foramen ovale. In 19 patients with transesophageal positive contrast studies, we assessed the value of the vertical versus the horizontal plane in the diagnosis of a patent foramen ovale. The patent foramen ovale opening could be seen and sized in the vertical plane in 10 studies (53%). In none of these 10 cases was the opening seen also in the horizontal plane. We conclude that in a significant number of cases, biplane transesophageal echocardiography adds morphological detail to the diagnosis of patent foramen ovale. The ability to size the actual opening may have therapeutic implications.

    View details for PubMedID 8217208

  • ABNORMAL POSTOPERATIVE INTERVENTRICULAR MOTION - NEW INTRAOPERATIVE TRANSESOPHAGEAL ECHOCARDIOGRAPHIC EVIDENCE SUPPORTS A NOVEL HYPOTHESIS AMERICAN HEART JOURNAL Wranne, B., Pinto, F. J., Siegel, L. C., Miller, D. C., Schnittger, I. 1993; 126 (1): 161-167

    Abstract

    Abnormal interventricular septal motion is a frequent finding after cardiac surgery. However, the time course and underlying mechanisms are not well understood. Nineteen patients, mean age 54 years (range 20 to 82 years), were studied with intraoperative transesophageal echocardiography at five specific times: with the chest closed (baseline), with the chest open and the pericardium closed, with both chest and pericardium open, after cardiopulmonary bypass with the chest open, and after cardiopulmonary bypass with the chest closed. In each patient interventricular septal motion was recorded from the transgastric view; tricuspid annular motion and Doppler color flow mapping of tricuspid regurgitation were obtained from the four-chamber view. All the echocardiographic data were stored on videotape and were later viewed in random sequence by one investigator who was aware of the baseline stage but was blinded to the other stages. All patients had normal septal motion before cardiopulmonary bypass. After cardiopulmonary bypass, with the chest still open, 5 of 17 patients (29%) with adequate recordings had abnormal septal motion while 13 of 17 patients (76%) with adequate recordings had abnormal tricuspid annular motion. After chest closure, only three patients (14%) had normal septal motion and one patient (6%) had normal tricuspid annular motion. Significant tricuspid regurgitation was an infrequent finding in all cases. It is concluded that abnormal interventricular septal motion occurs after cardiopulmonary bypass and is related to abnormal tricuspid annular motion. We hypothesize that suboptimal right ventricular myocardial preservation impairs the motion pattern of the right ventricle, including the tricuspid annulus.(ABSTRACT TRUNCATED AT 250 WORDS)

    View details for Web of Science ID A1993LL21000022

    View details for PubMedID 8322660

  • ASPECTS OF MECHANICAL VENTILATION AFFECTING INTERATRIAL SHUNT FLOW DURING GENERAL-ANESTHESIA ANESTHESIA AND ANALGESIA Jaffe, R. A., Pinto, F. J., Schnittger, I., Siegel, L. C., Wranne, B., BROCKUTNE, J. G. 1992; 75 (4): 484-488

    Abstract

    Intraoperative transesophageal echocardiography was used to study the incidence of flow-patent foramen ovale in 33 normal, healthy patients (ASA physical status I) undergoing general anesthesia in the supine position for nonthoracic surgical procedures. Echocardiographic contrast was injected intravenously during mechanical ventilation in the presence of 0, 5, 10, 15, or 19 cm H2O positive end-expiratory pressure (PEEP). A final test was performed during the release of 19 cm H2O PEEP. The presence of a flow-patent foramen ovale was detected when the injected echo targets were observed crossing the interatrial septum from right to left. Most interesting, 3 of 33 patients developed a right-to-left shunt that was first detected with the steady application of 10 (1 patient) or 15 cm H2O PEEP (2 patients). In all three cases, the shunt flow was accentuated on the release of PEEP; however, no additional cases were detected using this respiratory maneuver. These cases represent the first demonstration of right-to-left interatrial shunting evoked as the result of the sustained application of PEEP. This study also revealed a lower than expected incidence of flow-patent foramen ovale (9%) when measured during general anesthesia and positive pressure ventilation with or without PEEP.

    View details for Web of Science ID A1992JP53400003

    View details for PubMedID 1530158

  • SYSTEMIC VENOUS FLOW DURING CARDIAC-SURGERY EXAMINED BY INTRAOPERATIVE TRANSESOPHAGEAL ECHOCARDIOGRAPHY AMERICAN JOURNAL OF CARDIOLOGY Pinto, F. J., Wranne, B., STGOAR, F. G., Siegel, L. C., Haddow, G., Schnittger, I., Popp, R. L. 1992; 69 (4): 387-393

    Abstract

    Patterns of systemic venous return change after cardiac surgery. However, the exact timing and underlying mechanisms are not well understood. To analyze these changes transesophageal echocardiography was used to evaluate 21 patients (mean age 56 +/- 17 years) during cardiac surgery. Eleven patients underwent coronary bypass grafting, 2 had ablation of accessory bundles, 4 had mitral and 4 had aortic valve replacements. All were in sinus rhythm and were undergoing their first cardiac operation. Hepatic and pulmonary venous flow, tricuspid annular motion, and signs of tricuspid regurgitation were recorded sequentially 5 times: (A) with chest closed, (B) with chest open and pericardium closed, (C) with both chest and pericardium open, (D) after cardiopulmonary bypass with chest open, and (E) after cardiopulmonary bypass with chest closed. The hepatic venous Doppler flow velocity integrals (cm) changed, from stage A to stage E: systolic flow decreased from 5.9 +/- 5.2 to 2.2 +/- 1.4 (p less than 0.01); diastolic flow increased from 3.1 +/- 1.5 to 4.8 +/- 3.3 (p less than 0.001); and systolic to diastolic ratio decreased from 2.0 +/- 1.2 to 0.7 +/- 0.6 (p less than 0.001). Reversed flow at the end of ventricular systole was present in 9 patients (43%) at stage A and in all patients at stage E. Decreased tricuspid annular motion was noted in all but 1 patient after cardiopulmonary bypass. No patient presented significant tricuspid regurgitation at any stage. In conclusion, the significant change in the pattern of systemic venous return after open heart surgery is not due to opening of the chest wall or parietal pericardium, or to tricuspid regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

    View details for Web of Science ID A1992HB24800018

    View details for PubMedID 1734654

  • TRANSESOPHAGEAL ECHOCARDIOGRAPHY FOR STUDY OF BIOPROSTHESES IN THE AORTIC-VALVE POSITION AMERICAN JOURNAL OF CARDIOLOGY Pinto, F. J., Wranne, B., Schnittger, I. 1992; 69 (3): 274-276

    View details for Web of Science ID A1992GZ65200028

    View details for PubMedID 1731474

  • LEFTWARD SHIFT OF THE INTERVENTRICULAR SEPTUM AND PULSUS PARADOXUS IN OBSTRUCTIVE SLEEP-APNEA SYNDROME CHEST Shiomi, T., Guilleminault, C., Stoohs, R., Schnittger, I. 1991; 100 (4): 894-902

    Abstract

    Echocardiograms were taken from the parasternal long axis view during nocturnal sleep in ten patients diagnosed with OSAS. A table designed to support the echocardiographic probe prevented significant sleep disturbances during monitoring and allowed continuous data collection with and without nasal CPAP administration. In five of ten patients, there was before CPAP treatment a diastolic LSIVS during NREM sleep, inducing a flattening of the left ventricle. Arterial blood pressure recordings showed pulsus paradoxus when LSIVS was occurring. Nasal CPAP led to normal, unobstructed breathing, significant decrease in Pes nadir and disappearance of LSIVS and pulsus paradoxus. Increase in left ventricular afterload and increase in total peripheral resistance could lead to hypertrophy and hypertension in some OSAS patients. The presence of pulsus paradoxus in OSAS indicates a marked increase in Pes nadir, and its disappearance with nasal CPAP may be one of the signs of effective treatment of OSAS.

    View details for Web of Science ID A1991GK14700005

    View details for PubMedID 1914603

  • Transesophageal echo-Doppler echocardiographic assessment of pulmonary venous flow patterns. Journal of the American Society of Echocardiography BARTZOKIS, T., LEE, R., YEOH, T. K., GROGIN, H., Schnittger, I. 1991; 4 (5): 457-464

    Abstract

    Fifty-eight of 61 consecutive patients undergoing transesophageal echo-Doppler echocardiography provided excellent signals to permit assessment of pulmonary venous blood low patterns. Normal antegrade pulmonary venous flow during ventricular systole was biphasic and was characterized by a short, low velocity (28 +/- 17 cm/sec), early systolic jet (P1), and longer, higher velocity (41 +/- 23 cm/sec), late systolic jet (P2). Antegrade pulmonary venous flow during ventricular diastole (P3) was of moderate velocity (34 +/- 17 cm/sec) and was monophasic; during atrial contraction there was transient, low velocity (-17 +/- 11 cm/sec) and reversal of flow (P4). The early systolic antegrade venous flow (P1) was absent or reversed in rhythm disorders, which interrupted normal synchronized atrioventricular activation. These rhythm disorders also were associated with diminished peak flow velocities during late systole (P2). Abnormalities in systolic left ventricular function and mitral regurgitation also had this effect. Diastolic flow velocities (P3) remained constant, except in patients with mitral regurgitation. In these patients diastolic peak flows were significantly increased above normal. In cases of atrial fibrillation or ventricular pacing the late diastolic reversal of flow resulting from atrial contraction (P4) was absent. Conclusions: Transesophageal echo-Doppler echocardiography gives high quality signals of pulmonary venous inflow to help assess function of the left ventricle and left atrium. Multiple factors affect the patterns. This study suggests caution in the interpretation of abnormal patterns, particularly of reduced systolic pulmonary vein flow in the presence of left ventricular dysfunction, atrial fibrillation, ventricular pacing, and mitral regurgitation.

    View details for PubMedID 1742033

  • INTRAOPERATIVE VENTILATOR-INDUCED RIGHT-TO-LEFT INTRACARDIAC SHUNT ANESTHESIOLOGY Jaffe, R. A., Pinto, F. J., Schnittger, I., BROCKUTNE, J. G. 1991; 75 (1): 153-155

    View details for Web of Science ID A1991FU01700027

    View details for PubMedID 2064044

  • FREQUENCY AND MECHANISM OF BRADYCARDIA IN CARDIAC TRANSPLANT RECIPIENTS AND NEED FOR PACEMAKERS AMERICAN JOURNAL OF CARDIOLOGY Dibiase, A., Tse, T. M., Schnittger, I., Wexler, L., Stinson, E. B., Valantine, H. A. 1991; 67 (16): 1385-1389

    Abstract

    Orthotopic cardiac transplantation is occasionally complicated by unexplained bradyarrhythmias. Sinus node injury as a consequence of operation or acute rejection has anecdotally been linked to the development of bradycardia early after transplantation. These arrhythmias are empirically managed by pacemaker implantation, the indications for which remain poorly defined. This retrospective study examined the 20-year experience of our institution with bradyarrhythmias after transplantation to determine the predisposing factors and indications for pacemaker implantation. Forty-one of 556 patients in our cardiac transplant program (7.4%) received permanent pacemakers between 1969 and 1989. The predominant rhythm disturbances were junctional rhythm (46%), sinus arrest (27%) and sinus bradycardia (17%). Most patients were asymptomatic (61%), and presented in the early post-transplant period (73%). Four possible predisposing factors were evaluated: (1) graft ischemic time, (2) rejection history, (3) use of bradycardia-inducing drugs, and (4) anatomy of blood supply to the sinoatrial (SA) node. No significant differences existed between patients with and without pacemakers with regard to the first 3 variables. However, after transplantation angiograms showed that prevalence of abnormal SA nodal arteries was greater in patients with than without pacemakers (p less than 0.02). Pacemaker follow-up at 3, 6 and 12 months showed persistent bradycardia (60 to 90 beats/min) in 88, 75 and 50% of patients, respectively. The most common pacemaker complication (15%) was lead displacement at time of biopsy. These results suggest that disruption of the SA nodal blood supply may be an important predisposing factor in the development of bradycardias.

    View details for Web of Science ID A1991FR02000014

    View details for PubMedID 2042569

  • ENHANCED DETECTION OF INTRACARDIAC SOURCES OF CEREBRAL EMBOLI BY TRANSESOPHAGEAL ECHOCARDIOGRAPHY STROKE Lee, R. J., BARTZOKIS, T., YEOH, T. K., GROGIN, H. R., Choi, D., Schnittger, I. 1991; 22 (6): 734-739

    Abstract

    We performed transesophageal echocardiography in 50 consecutive hospitalized patients with recent transient ischemic attack or stroke of embolic origin to determine whether transesophageal echocardiography is more sensitive than transthoracic echocardiography in detection of possible intracardiac sources of embolism. Twenty-six of 50 patients with a negative transthoracic echocardiogram for potential source of emboli had a transesophageal echocardiography study that demonstrated at least one intracardiac abnormality. Abnormalities noted by transesophageal echocardiography included five of 50 patients with either a left atrial or left atrial appendage clot, four patients with a patent foramen ovale, and nine patients with spontaneous echocardiographic contrast. In 11 of 50 patients with no other source of embolism, we found highly mobile filamentous strands on the mitral valve, which have not been described previously. These mitral valve echo strands may represent a fissured surface or fibrosis that can serve as a nidus for thrombus formation. We detected no unexpected left ventricular thrombus or left atrial myxoma. Factors significantly associated with a greater likelihood of a positive transesophageal echocardiography study included left atrial enlargement, atrial fibrillation, and a calcified or thickened mitral valve. Our study suggests that transesophageal echocardiography is a valuable addition to transthoracic echocardiography in investigating potential intracardiac sources of embolism.

    View details for Web of Science ID A1991FQ99800004

    View details for PubMedID 2057971

  • HEPATIC VENOUS FLOW ASSESSED BY TRANSESOPHAGEAL ECHOCARDIOGRAPHY JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Pinto, F. J., Wranne, B., STGOAR, F. G., Schnittger, I., Popp, R. L. 1991; 17 (7): 1493-1498

    Abstract

    Systemic venous flow patterns are easily assessed by transthoracic echocardiography for evaluation of right heart dynamics. However, the transthoracic approach cannot be used in patients undergoing thoracic surgery. The present study describes a method for obtaining hepatic venous flow velocity with transesophageal Doppler echocardiography. Twenty-nine patients were studied with transthoracic echocardiography just before cardiac surgery and with transesophageal echocardiography during surgery. Hepatic venous flow velocity recordings were obtained in 14 of 29 patients with the transthoracic and in all 29 with the transesophageal approach. Timing of flow pattern was similar with the two methods, but recordings obtained with transesophageal echocardiography were inverted compared with those obtained with transthoracic echocardiography as a result of the difference in probe location in relation to flow direction. The time-velocity integrals obtained with the two techniques did not differ significantly; for the transthoracic and transesophageal approaches, they were, respectively, 7.3 +/- 3.4 versus 5.7 +/- 4.4 for systolic flow; 1.0 +/- 1.0 versus 0.5 +/- 0.6 for end-systolic flow reversal; 4.7 +/- 2.3 versus 3.7 +/- 1.7 for diastolic flow; 2.0 +/- 1.8 versus 1.5 +/- 1.5 for atrial flow reversal and 1.9 +/- 1.0 versus 1.7 +/- 1.1 for systolic/diastolic ratio. In conclusion, hepatic venous flow values are obtained more frequently and with better quality by transesophageal than by transthoracic echocardiography. The flow patterns and velocity integrals are similar with both methods and previous experience with transthoracic echocardiography should be applicable to the transesophageal technique. Transesophageal Doppler echocardiography therefore has potential for studying right heart dynamics during anesthesia and surgery.

    View details for Web of Science ID A1991FQ22900008

    View details for PubMedID 2033181

  • LEFT-VENTRICULAR DIASTOLIC FUNCTION - DOPPLER ECHOCARDIOGRAPHIC CHANGES SOON AFTER CARDIAC TRANSPLANTATION CIRCULATION STGOAR, F. G., Gibbons, R., Schnittger, I., Valantine, H. A., Popp, R. L. 1990; 82 (3): 872-878

    Abstract

    In acute cardiac rejection, left ventricular diastolic function is altered, and a restrictive ventricular filling pattern occurs. Doppler echocardiographic indexes of mitral inflow have been proposed as sensitive markers of the rejection process. As rejection progresses, the restrictive ventricular filling pattern is reflected by a shortening of isovolumic relaxation time and mitral valve pressure half-time and by an increase in early transmitral filling velocity. Diastolic function is also compromised in the nonrejecting cardiac transplant recipient during the early postoperative period. This study examined the progression in Doppler-derived mitral filling indexes in 25 recent cardiac transplant recipients who demonstrated no histological evidence of transplant rejection. Isovolumic relaxation time, mitral valve pressure half-time, and early transmitral filling velocity were measured at postoperative weeks 1, 2, 4, and 6 on the day that surveillance right ventricular endomyocardial biopsies were performed. The initial indexes were comparable to previously described restrictive parameters and over the 6-week study period evolved into a nonrestrictive filling pattern. This evolution reflects a progressive improvement in postoperative diastolic function and a decrease in left heart filling pressures. None of the evaluated clinical characteristics, including preoperative pulmonary pressures, total ischemic time of the transplanted heart, cardiopulmonary bypass time, and age of the donor heart, correlated with this process. Given the increasing use of Doppler echocardiography as a means of screening for transplant rejection, it is important to have a thorough understanding of normal postoperative changes in left ventricular diastolic function.

    View details for Web of Science ID A1990DY27700018

    View details for PubMedID 2394008

  • SERIAL MEASUREMENT OF INTEGRATED ULTRASONIC BACKSCATTER IN HUMAN CARDIAC ALLOGRAFTS FOR THE RECOGNITION OF ACUTE REJECTION CIRCULATION Masuyama, T., Valantine, H. A., Gibbons, R., Schnittger, I., Popp, R. L. 1990; 81 (3): 829-839

    Abstract

    Cyclic variation of integrated ultrasonic backscatter (IB) was noninvasively measured in the septum and left ventricular posterior wall using a quantitative IB imaging system to assess the alterations in the acoustic properties of myocardium associated with acute cardiac allograft rejection. The study population consisted of 23 cardiac allograft recipients and 18 normal subjects. In each cardiac allograft recipient, one to eight (mean, four) IB studies were performed, each within 24 hours of right ventricular endomyocardial biopsy performed for rejection surveillance. The magnitude of the cyclic variation of IB in the posterior wall was 5.9 +/- 0.9 dB in normal subjects and 6.2 +/- 1.3 dB in the cardiac allograft recipients without previous or current histological evidence of acute rejection (n = 17, p = NS vs. normal subjects). The magnitude of cyclic variation of IB in the septum was 4.8 +/- 1.1 dB in normal subjects and 3.8 +/- 2.0 dB in the cardiac allograft recipients (n = 15, p = NS vs. normal subjects). A significant decrease in the septal IB measure was observed in cardiac allograft recipients with left ventricular hypertrophy (wall thickness of at least 13 mm) (2.6 +/- 1.7 dB, n = 8, p less than 0.05 vs. normal subjects). IB studies were done before and during moderate acute rejection in 11 recipients (14 episodes). During moderate acute cardiac rejection, the magnitude of the cyclic variation in IB decreased from 6.7 +/- 1.3 to 5.1 +/- 1.4 dB in the posterior wall (n = 14, p less than 0.05) and from 4.2 +/- 2.1 dB to 2.9 +/- 1.8 dB in the septum (n = 12, p less than 0.05). These data suggest 1) the magnitude of the cyclic variation in IB of the septum is different in cardiac allografts with cardiac hypertrophy and normal subjects, possibly reflecting regionally depressed myocardial contractile performance and 2) acute cardiac rejection in humans is accompanied by an alteration in the acoustic properties of the myocardium. This change is detectable by serial measurement of the magnitude of the cyclic variation in IB, both in the septum and in the posterior wall.

    View details for Web of Science ID A1990CT01400012

    View details for PubMedID 2306834

  • Flow velocity acceleration in the left ventricle: a useful Doppler echocardiographic sign of hemodynamically significant mitral regurgitation. Journal of the American Society of Echocardiography Appleton, C. P., Hatle, L. K., Nellessen, U., Schnittger, I., Popp, R. L. 1990; 3 (1): 35-45

    Abstract

    Doppler echocardiography is a sensitive method to detect mitral regurgitation in patients with both native and prosthetic valves. However, estimates of the amount of mitral regurgitation remain semiquantitative, and even severe mitral regurgitation may be underestimated in the presence of markedly eccentric regurgitant jets or acoustic shadowing of the left atrium by mitral or aortic prostheses. This report describes the Doppler findings in 10 patients with severe native valve mitral regurgitation (angiographic grade III or IV) and in 15 patients with severe bioprosthetic mitral regurgitation that required valve replacement. An increase in peak mitral flow velocity above normal values was seen in eight of 10 patients with severe native valve mitral regurgitation (greater than or equal to 130 cm per second) and 11 of 15 patients with severe prosthetic valve mitral regurgitation (greater than or equal to 210 cm per second). One of 10 patients with a native valve and four of 15 patients with a bioprosthetic valve appeared to have only a localized left atrial systolic flow disturbance, incorrectly suggesting that the mitral regurgitation was mild. However, in all patients with severe mitral regurgitation, a low velocity (less than 100 cm per second) flow signal could be recorded in the left ventricle that was directed toward the mitral valve in systole. This flow signal showed a gradual increase in velocity as the sample volume was moved toward the mitral valve, with an abrupt further increase on entry into the left atrium. This signal was continuous with antegrade mitral flow and had the same orientation as mitral regurgitation recorded by continuous wave technique from the apex. A similar flow signal was not recorded in the left ventricle of any individual in a control group of 30 patients who had no mitral regurgitation or who had angiographic grade I or II mitral regurgitation. These findings suggest that acceleration of left ventricle flow toward the mitral valve in systole is only recorded when there is hemodynamically significant mitral regurgitation that is approximately equal to angiographic grade III or IV. Recognition of this Doppler finding may help in the estimation of mitral regurgitation severity, especially in difficult diagnostic situations.

    View details for PubMedID 2310590

  • ULTRASONIC TISSUE CHARACTERIZATION WITH A REAL-TIME INTEGRATED BACKSCATTER IMAGING-SYSTEM IN NORMAL AND AGING HUMAN HEARTS JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Masuyama, T., Nellessen, U., Schnittger, I., Tye, T. L., Haskell, W. L., Popp, R. L. 1989; 14 (7): 1702-1708

    Abstract

    Experimental studies have shown that variation in the magnitude of integrated ultrasonic backscatter during the cardiac cycle represents acoustic properties of myocardium that are affected by pathologic processes; however, there are few clinical studies using integrated backscatter. Forty subjects without cardiovascular disease (aged 22 to 71 years, mean 41) were studied with use of a new M-mode format integrated backscatter imaging system to characterize the range of cyclic variation of integrated backscatter in normal subjects. Cyclic variation in integrated backscatter was noted in both the septum and the posterior wall in all subjects. The magnitude of the cyclic variation of integrated backscatter and the interval from the onset of the QRS wave of the electrocardiogram to the minimal integrated backscatter value were measured using an area of interest of variable size for integrated backscatter sampling and a software resident in the ultrasound scanner. The magnitude of cyclic variation was larger for the posterior wall than for the septum (6.3 +/- 0.8 versus 4.9 +/- 1.3 dB, p less than 0.01). The interval to the minimal integrated backscatter value was 328 +/- 58 ms for the septum and 348 +/- 42 ms for the posterior wall (p = NS). There was a weak correlation between the magnitude of cyclic variation of integrated backscatter and subject age for the posterior wall (r = -0.47, p less than 0.01), but this was not significant for the septum (r = -0.21) (partially because of inability to exclude specular septal echoes) and septal endocardium.(ABSTRACT TRUNCATED AT 250 WORDS)

    View details for Web of Science ID A1989CE08600019

    View details for PubMedID 2685077

  • TRANSESOPHAGEAL ECHOCARDIOGRAPHY - AN INTRODUCTION FOR ULTRASONOGRAPHERS JOURNAL OF DIAGNOSTIC MEDICAL SONOGRAPHY Tye, T. L., Nellessen, U., Schnittger, I., Popp, R. 1989; 5 (6): 316-321
  • ULTRASONIC TISSUE CHARACTERIZATION OF HUMAN HYPERTROPHIED HEARTS INVIVO WITH CARDIAC CYCLE-DEPENDENT VARIATION IN INTEGRATED BACKSCATTER CIRCULATION Masuyama, T., STGOAR, F. G., Tye, T. L., Oppenheim, G., Schnittger, I., Popp, R. L. 1989; 80 (4): 925-934

    Abstract

    Integrated ultrasonic backscatter (IB) is a noninvasive measure of the acoustic properties of myocardium. Previous experimental studies have indicated that altered acoustic properties of the myocardium are reflected by the magnitude of variation of IB during the cardiac cycle. In our study, cardiac cycle-dependent variation of IB was noninvasively measured using a quantitative IB imaging system in 12 patients with uncomplicated pressure-overload hypertrophy and 13 patients with hypertrophic cardiomyopathy. Sixteen normal subjects served as a control. The magnitude of cardiac cycle-dependent variation of IB for the posterior wall was 6.0 +/- 0.9 dB in normal subjects, 5.7 +/- 0.8 dB in the patients with uncomplicated pressure-overload hypertrophy, and 6.7 +/- 2.1 dB in the patients with hypertrophic cardiomyopathy. There were no significant differences among any of these groups. In contrast, the magnitude of cardiac cycle-dependent variation of IB for the septum was significantly smaller in the patients with uncomplicated pressure-overload hypertrophy (2.8 +/- 1.3 dB) and in the patients with hypertrophic cardiomyopathy (3.1 +/- 2.3 dB) than in normal subjects (4.9 +/- 1.0 dB). The magnitude of cardiac cycle-dependent variation of IB was smaller as the wall-thickness index increased (r = -0.53, p less than 0.01, n = 82 for all data). This IB measure also correlated with percent-systolic thickening of the myocardium (r = 0.67, p less than 0.01, n = 82). Thus, alteration in the magnitude of cardiac cycle-dependent variation of IB was observed in hypertrophic hearts and showed apparent regional myocardial differences.

    View details for Web of Science ID A1989AW00100020

    View details for PubMedID 2529060

  • LONG-TERM RESULTS OF ANTITACHYCARDIA PACING IN PATIENTS WITH SUPRAVENTRICULAR TACHYCARDIA PACE-PACING AND CLINICAL ELECTROPHYSIOLOGY Schnittger, I., Lee, J. T., Hargis, J., Wyndham, C. R., ECHT, D. S., Swerdlow, C. D., Griffin, J. C. 1989; 12 (6): 936-941

    Abstract

    Between 1979 and 1984 the Cybertach-60, (Intermedics, Inc. Model 262-01), a programmable, automatic antitachycardia pacemaker was implanted in 11 patients who had drug-refractory supraventricular tachycardia (SVT). The patients have been followed for a total of 64-108 (mean 84 months). All patients were symptomatic and had failed two or more drugs and six patients had required prior DC cardioversion. The mechanism of supraventricular tachycardia was atrioventricular (AV) nodal reentry in six patients, AV reentry in four patients, and atrial tachycardia in one patient. Preoperatively all patients had reliable termination of the tachycardia without induction of atrial fibrillation by pacing methods available to Cybertach-60. Postimplant, Cybertach-60 reliably terminated all episodes of tachycardia without ancillary drug therapy. Nevertheless, at long-term follow-up antitachycardia pacing was effective and safe in the minority (36%), with only four patients out of eleven still using a pacemaker for supraventricular tachycardia. One of these four patients required additional drug therapy. In one of the patients, the Cybertach-60 was replaced after 78 months by a more advanced device, (Intertach, Intermedics, Inc.) because of a depleted Cybertach-60 battery. In seven patients who no longer use antitachycardia pacing for termination of tachycardia, one patient developed atrial fibrillation during tachycardia termination (at 58 months postimplant). Three patients experienced induction of tachycardia or atrial fibrillation by the pacemaker due to undersensing of sinus P waves (at 36, 48, and 51 months).(ABSTRACT TRUNCATED AT 250 WORDS)

    View details for Web of Science ID A1989AK02100009

    View details for PubMedID 2472621

  • Doppler diagnosis of left ventricle to coronary sinus fistula: an unusual complication of mitral valve replacement. Journal of the American Society of Echocardiography YEE, G. W., NAASZ, C., Hatle, L., PIPKIN, R., Schnittger, I. 1988; 1 (6): 458-462

    View details for PubMedID 3272796

  • TRANS-ESOPHAGEAL TWO-DIMENSIONAL ECHOCARDIOGRAPHY AND COLOR DOPPLER FLOW VELOCITY MAPPING IN THE EVALUATION OF CARDIAC-VALVE PROSTHESES CIRCULATION Nellessen, U., Schnittger, I., Appleton, C. P., Masuyama, T., Bolger, A., Fischell, T. A., Tye, T., Popp, R. L. 1988; 78 (4): 848-855

    Abstract

    To determine the value of transesophageal ultrasound in the assessment of cardiac valve prostheses, 14 patients with clinically suspected mitral prosthesis malfunction were studied by transthoracic and transesophageal two-dimensional imaging as well as by color Doppler flow velocity mapping (color Doppler). Patients underwent left ventricular angiography (n = 13), surgery (n = 11), or both angiography and surgery (n = 10). Nine patients had only mitral valve replacement, four patients had both mitral and aortic valve replacement, and one patient had mitral, aortic, and tricuspid valve replacement. There were 16 biological and four mechanical prostheses. The degree of mitral regurgitation was graded by both transthoracic and transesophageal color Doppler according to the area of the regurgitant jet visualized and was compared with a three-point classification of mitral regurgitation by left ventricular angiography judged by observers blinded to the echocardiographic results. All transesophageal studies were performed without complication and were well tolerated. The pathological morphology of the mitral prosthesis was additionally or more clearly visualized by transesophageal two-dimensional imaging and subsequently proven at surgery in three patients with flail leaflets and one patient with a vegetation compared with images obtained by the transthoracic approach. Valvular regurgitation was graded by the transthoracic approach as absent in four patients, mild in two patients, moderate in five patients, and severe in only three patients. The transesophageal assessment showed absence of mitral regurgitation in two patients, moderate regurgitation in two patients, and severe regurgitation in 10 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

    View details for Web of Science ID A1988Q654900007

    View details for PubMedID 3168192

  • DIASTOLIC MITRAL AND TRICUSPID REGURGITATION BY DOPPLER ECHOCARDIOGRAPHY IN PATIENTS WITH ATRIOVENTRICULAR-BLOCK - NEW INSIGHT INTO THE MECHANISM OF ATRIOVENTRICULAR VALVE CLOSURE JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Schnittger, I., Appleton, C. P., Hatle, L. K., Popp, R. L. 1988; 11 (1): 83-88

    Abstract

    The purpose of this study was to prospectively determine the incidence of diastolic mitral and tricuspid regurgitation in atrioventricular (AV) block using Doppler echocardiography. The temporal relation between mitral and tricuspid diastolic insufficiency and the diastolic murmur recorded in patients with complete heart block was also investigated. Twenty-two consecutive patients with AV block (referred to the Echo-Doppler laboratory for routine clinical studies), aged 18 to 87 years, were enrolled in the study. Eleven patients had third degree AV block and a ventricular-inhibited (VVI) pacemaker, two patients had second degree AV block, seven patients had first degree AV block, one patient had blocked premature atrial complexes and one patient had atrial flutter with 4:1 AV block. Diastolic mitral regurgitation was detected in 20 patients, and diastolic tricuspid regurgitation in 21. A mid-diastolic murmur was detected in all patients except in the three youngest. The murmur occurred before diastolic regurgitation and coincided with peak forward flow through the AV valve after atrial contraction. M-mode mitral valve echocardiograms obtained in nine patients demonstrated near closure of some portions of the mitral valve after atrial contraction. Effective closure of the valve, however, did not occur unless ventricular systole supervened. In conclusion, diastolic mitral and tricuspid regurgitation are almost universally present in patients with AV block and are associated with a diastolic murmur. The murmur coincides with forward AV valve flow. Diastolic regurgitation is silent. Effective AV valve closure is not established until ventricular systole occurs, as demonstrated by M-mode echocardiographic recording of the mitral valve.

    View details for Web of Science ID A1988L604800013

    View details for PubMedID 3335709

Conference Proceedings


  • ECHOCARDIOGRAPHIC STUDIES IN ADULTS AND CHILDREN PRESENTING WITH OBSTRUCTIVE SLEEP-APNEA OR HEAVY SNORING Guilleminault, C., Shiomi, T., Stoohs, R., Schnittger, I. INST NATL SANTE RECHERCHE MEDICALE. 1991: 95-103

Stanford Medicine Resources: