OBJECTIVE: The objective was to design and evaluate a clinically relevant, novel exvivo bicuspid aortic valve model that mimics the most common human phenotype with associated aortic regurgitation.METHODS: Three bovine aortic valves were mounted asymmetrically in a previously validated 3-dimensional-printed left heart simulator. The non-right commissure and the non-left commissure were both shifted slightly toward the left-right commissure, and the left and right coronary cusps were sewn together. The left-right commissure was then detached and reimplanted 10mm lower than its native height. Free margin shortening was used for valve repair. Hemodynamic status, high-speed videography, and echocardiography data were collected before and after the repair.RESULTS: The bicuspid aortic valve model was successfully produced and repaired. High-speed videography confirmed prolapse of the fused cusp of the baseline bicuspid aortic valve models in diastole. Hemodynamic and pressure data confirmed accurate simulation of diseased conditions with aortic regurgitation and the subsequent repair. Regurgitant fraction postrepair was significantly reduced compared with that at baseline (14.5 ± 4.4% vs 28.6%±3.4%; P=.037). There was no change in peak velocity, peak gradient, or mean gradient across the valve pre- versus postrepair: 293.3±18.3cm/sec versus 325.3±58.2cm/sec (P=.29), 34.3±4.2mm Hg versus 43.3±15.4mm Hg (P=.30), and 11±1mm Hg versus 9.3±2.5mm Hg (P=.34), respectively.CONCLUSIONS: An exvivo bicuspid aortic valve model was designed that recapitulated the most common human phenotype with aortic regurgitation. These valves were successfully repaired, validating its potential for evaluating valve hemodynamics and optimizing surgical repair for bicuspid aortic valves.
View details for DOI 10.1016/j.jtcvs.2020.06.028
View details for PubMedID 32747120
Although ex vivo simulation is a valuable tool for surgical optimization, a disease model that mimics human aortic regurgitation (AR) from cusp prolapse is needed to accurately examine valve biomechanics. To simulate AR, four porcine aortic valves were explanted, and the commissure between the two largest leaflets was detached and re-implanted 5 mm lower to induce cusp prolapse. Four additional valves were tested in their native state as controls. All valves were tested in a heart simulator while hemodynamics, high-speed videography, and echocardiography data were collected. Our AR model successfully reproduced cusp prolapse with significant increase in regurgitant volume compared with that of the controls (23.2?±?8.9 versus 2.8?±?1.6 ml, p?=?0.017). Hemodynamics data confirmed the simulation of physiologic disease conditions. Echocardiography and color flow mapping demonstrated the presence of mild to moderate eccentric regurgitation in our AR model. This novel AR model has enormous potential in the evaluation of valve biomechanics and surgical repair techniques. Graphical Abstract.
View details for DOI 10.1007/s12265-020-10038-z
View details for PubMedID 32495264
BACKGROUND: The long-term benefits of Melody valve implant for right ventricular outflow tract conduit obstruction or insufficiency on exercise capacity are undefined.METHODS: As part of the Melody valve clinical trial, 136 patients with congenital heart disease underwent serial cardiopulmonary exercise testing prior to, 6 months after, and annually for up to 5 years postimplant.RESULTS: Mean age at Melody valve implantation was 22.4 ± 0.9 years (range 7-53 years). The 95 patients who completed the study protocol provide the basis of this report. An initial improvement in % predicted workload was present at 6 months postimplant; however, at the final (5 year) follow-up, sustained or further improvements in workload were not demonstrated for the entire cohort compared to baseline. By subgroup analysis, age <17 years at implant and pulmonary regurgitation as the primary lesion were variables associated with sustained improvement in exercise performance. There were sustained improvements in the ventilatory equivalents for O2 (minute ventilation/O2 intake, P = .01) and CO2 (minute ventilation/CO2 output, P < .01) at the ventilatory anaerobic threshold at the study conclusion. Improvements in forced vital capacity were also observed during the study but not sustained at the final follow-up.CONCLUSIONS: A cautious appraisal of the cardiovascular benefits of Melody valve implant on sustained improvements in exercise performance appears warranted. Although the observed changes in pulmonary function suggest improved restrictive lung physiology and more efficient gas exchange, after an initial increase in % predicted performance, neither sustained nor further improvements in exercise performance were observed, except in specific patient subgroups.
View details for PubMedID 30682562
Although percutaneous Melody valve implant has become an accepted alternative to surgical pulmonary valve replacement in patients with congenital heart disease, the benefit regarding frequency and severity of arrhythmias remains undefined.The purpose of this study was to evaluate the impact of Melody valve implant on the type and frequency of arrhythmias during cardiopulmonary exercise testing (CPET) and subsequent clinical outcome.As part of the phase I Melody valve clinical trial, 136 patients with congenital heart disease underwent prospective serial evaluation including CPET before implant, 6 months after implant, and annually thereafter for 5 years. Arrhythmias were defined as premature ventricular complexes (PVCs) and supraventricular or ventricular tachycardia (VT).Before Melody implant, PVCs occurred in 55 patients (40%) and nonsustained ventricular tachycardia (NSVT) in 1 patient during CPET. Median age at valve implantation was 19.0 years (range 7-53 years). During median follow-up of 4.9 years (range 0.8-7.3 years), there was no significant change in the proportion of patients with PVCs during CPET at any follow-up interval (40%-45%). However, postimplant, NSVT occurred in 18 patients, including 8 during CPET. Diagnoses in the patients with NSVT were tetralogy of Fallot (11), transposition (2), and post-Ross procedure (5). Improved hemodynamic status was not associated with resolution or prevention of arrhythmias.Despite improvement in hemodynamics, Melody valve implant was not associated with resolution or prevention of arrhythmias during CPET. PVCs or VT may be related to pathologic hypertrophy, fibrosis, dilation, or possible mechanical effects of the Melody device.
View details for DOI 10.1016/j.hrthm.2016.07.023
View details for PubMedID 27453127
The utility of cardiopulmonary exercise testing (CPET) to define the risks of arrhythmia and sudden death in postoperative patients with congenital heart disease (CHD) remains uncertain. As part of the US Melody valve trial, prospective standardized CPET, along with echocardiography, cardiac magnetic resonance imaging, and cardiac catheterization, were performed in 170 CHD patients with right ventricular outflow tract conduit dysfunction before Melody valve implantation. Ventricular premature complexes (VPC) occurred in 75 patients (44%) and were common during all phases of CPET (13% baseline, 24% exercise, and 23% recovery). Although no subjects had sustained arrhythmias, 2 had nonsustained ventricular tachycardia and 3 had nonsustained supraventricular tachycardia during recovery. There were no statistically significant differences between patients with or without VPCs in echocardiographic, cardiac magnetic resonance imaging, or catheterization measures of cardiac function. However, clinical parameters of age, New York Heart Association functional class ?II, and ?3 cardiac surgical procedures were correlated with VPCs. Persistent ventricular ectopy during all exercise stages was present in 11 patients (6.5%), including 3 of the 4 patients who died during follow-up. In conclusion, VPCs were common during CPET, although they were not correlated with various measures of hemodynamic impairment; conversely, increased age, functional class, and number of surgeries were correlated with an increased prevalence of VPCs. CPET appears to be of minimal risk for sustained arrhythmia provocation in CHD patients with right ventricular outflow tract conduits and various degrees of advanced subpulmonary ventricular dysfunction.
View details for DOI 10.1016/j.amjcard.2014.05.019
View details for PubMedID 24931290
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A leader in the biomedical revolution, Stanford Medicine has a long tradition of leadership in pioneering research, creative teaching protocols and effective clinical therapies.
An at-home COVID-19 test, designed by Stanford researchers to be easy to use and provide results within 30 minutes, will be the focus of a study funded by the Stanford Medicine Catalyst Program.
Our scientists have launched dozens of research projects as part of the global response to COVID-19. Some aim to prevent, diagnose and treat the disease; others aim to understand how it spreads and how people?s immune systems respond to it.
A subtype of a popular antibiotic could pose a smaller risk of hearing loss yet still be powerful at fighting off bacterial infections.
Lab scientists at Stanford Medicine are processing thousands of samples a day, fighting the coronavirus pandemic behind the scenes.
A look at Stanford Medicine?s response to the new coronavirus, as well as outside perspectives on the pandemic.
Latest information on COVID-19
Stanford Medicine is closely monitoring the outbreak of novel coronavirus (COVID-19). A new page is dedicated to the latest information and developments about COVID-19.
Racism and discrimination are direct affronts to Stanford Medicine?s values. Read our leaders? pledge on racial equity.
A leader in the biomedical revolution, Stanford Medicine has a long tradition of leadership in pioneering research, creative teaching protocols and effective clinical therapies.
An at-home COVID-19 test, designed by Stanford researchers to be easy to use and provide results within 30 minutes, will be the focus of a study funded by the Stanford Medicine Catalyst Program.
Our scientists have launched dozens of research projects as part of the global response to COVID-19. Some aim to prevent, diagnose and treat the disease; others aim to understand how it spreads and how people?s immune systems respond to it.
A subtype of a popular antibiotic could pose a smaller risk of hearing loss yet still be powerful at fighting off bacterial infections.
Lab scientists at Stanford Medicine are processing thousands of samples a day, fighting the coronavirus pandemic behind the scenes.
A look at Stanford Medicine?s response to the new coronavirus, as well as outside perspectives on the pandemic.
