Surgical Treatment of Hypertrophic Cardiomyopathy

About the Stanford Hypertrophic Cardiomyopathy Center

Genetic Testing and Advanced Care for Families With Heart Disease

The Stanford Hypertrophic Cardiomyopathy Center is a Hypertrophic Cardiomyopathy Association Recognized Center of Excellence. As an established center, our dedicated multidisciplinary team of cardiologists, surgeons, radiologists, anesthesiologists, electrophysiologists, genetic counselors, and other allied health professionals provide high-quality care to patients with hypertrophic cardiomyopathy (HCM). Stanford’s expertise and experience in caring for a high volume of HCM patients have enabled us to provide patients with resources and knowledge tailored to their specific situations.

About Hypertrophic Cardiomyopathy

What is hypertrophic cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is a genetic heart condition that causes the heart muscle to become abnormally thickened and stiff. The overgrowth of tissue most commonly occurs in the ventricular septum, the wall separating the right and left ventricles of the heart. The thickened septum often bulges into the left ventricle and partially obstructs blood flow from the heart to the rest of the body. The stiffened tissue also prevents the heart from relaxing properly to fill with an adequate amount of blood to meet the body’s demands.

A subset of individuals with hypertrophic cardiomyopathy also has concurrent mitral valve disease that can further contribute to the obstruction of blood flow.

Patients diagnosed with hypertrophic cardiomyopathy can be more prone to developing life-threatening abnormal heart rhythms.

What causes hypertrophic cardiomyopathy?

Hypertrophic cardiomyopathy is an inheritable genetic condition that affects an estimated 1 in 500 individuals in the United States. Given the genetic nature of the disease, it is often recommended that family members undergo screening for the disease as well. Our center offers genetic testing and genetic counseling to help guide patients through the process.

What are the symptoms of hypertrophic cardiomyopathy?

Many patients with hypertrophic cardiomyopathy experience a number of symptoms. Commonly reported symptoms include:

  • Shortness of breath
  • Lightheadedness
  • Fainting/near-fainting
  • Palpitations/abnormal heartbeats
  • Chest pain

How do you diagnose hypertrophic cardiomyopathy?

There are a few clinical tests that can diagnose hypertrophic cardiomyopathy. The primary tests are listed below:

  • Transthoracic echocardiogram (TTE) or stress echocardiogram
  • Cardiac magnetic resonance imaging (CMRI)

In addition, medical history and physical exams are important factors in assessing the presence.

Why does hypertrophic cardiomyopathy need to be treated?

If the obstruction of blood flow out of the heart is significant enough, it can cause the heart to work harder, which, over time, may lead to heart failure. In addition, patients with hypertrophic cardiomyopathy are at a higher risk for sudden cardiac death.

Many patients with hypertrophic cardiomyopathy can be successfully treated with medications managed by their cardiologist. However, when medications alone are not able to adequately manage symptoms, other more invasive options are considered, such as septal myectomy.

Treating Hypertrophic Cardiomyopathy with Septal Myectomy

Overview of Septal Myectomy

A septal myectomy is an open-heart surgery procedure performed to treat hypertrophic cardiomyopathy. During this procedure, the surgeon removes the extra tissue of the thickened ventricular septum (the wall that separates the left and right ventricles) that is obstructing blood flow out of the heart.

Some patients with hypertrophic cardiomyopathy also have abnormal functioning of their mitral valve. Depending on the anatomy and underlying issue, sometimes the problem is addressed with just the septal myectomy alone. However, if the mitral valve disease is significant enough, the surgeon may also perform a mitral valve repair or replacement at the time of surgery.

Pre-Operative Testing

Prior to scheduling surgery, there are a few pre-operative tests you will need to obtain. Some tests are ordered to better characterize the anatomy and specific disease process. Other tests are routine screening/clearance tests ordered for all patients undergoing any type of cardiac surgery. Our clinical team will review your chart and help determine which tests will be necessary for you.

Commonly required pre-operative tests:

  • Coronary angiogram (LHC)
  • Transthoracic echocardiogram (TTE) and/or stress echocardiogram
  • Cardiac magnetic resonance imaging (CMRI)
  • Chest x-ray (CXR)
  • Electrocardiogram (ECG)
  • Blood tests

Intra-Operative Details

  • On the day of surgery, you will be brought to the operating room and a team of cardiac anesthesiologists will administer general anesthesia to keep you fully unconscious throughout the surgery.
  • The surgeon will begin the surgery by making a 6-8 inch incision down the middle of your chest and dividing the sternum (breastbone) to access the heart.
  • You will be placed on the cardiopulmonary bypass machine (heart-lung machine), which will oxygenate and circulate blood to the rest of the body while the surgeon works on the heart.
  • The surgeon will then perform the septal myectomy by removing the extra tissue of the thickened ventricular septum and if needed, a mitral valve repair or replacement.
  • The quality and durability of the repair will be assessed during the surgery to ensure that you leave the operating room with significant improvement of the left ventricular outflow tract obstruction.
  • When the repair is complete, the breastbone is brought back together with stainless steel wires that will remain in place. The overlying tissue and skin are closed with reabsorbable sutures. 
  • The total length of the operation can vary but typically takes 2-3 hours.

Immediate Post-Operative Period

  • Immediately after the surgery is completed, you will be transported to the Cardiovascular Intensive Care Unit (CVICU), which is standard for all patients that undergo open heart surgery. You will likely spend 1-2 days in the CVICU before moving to the regular cardiac surgery step-down unit, with a total hospital stay of approximately one week.
  • While in the hospital, you will work with our physical therapy and occupational therapy staff as soon as the first day after surgery.
  • If you require any special arrangements upon discharge (e.g. home health services, cardiac rehabilitation), our case managers and social workers will help ensure that everything is in order before you leave the hospital.


Once you are discharged from the hospital, you should be able to perform most of your daily activities independently. You will be restricted from lifting heavy objects for two months to allow adequate time for your breastbone to heal. You will also not be allowed to drive for one month.

"Septal myectomy remains the gold standard for managing left ventricular outflow tract obstruction in patients with hypertrophic obstructive cardiomyopathy. It is among the most rewarding surgeries I perform and patients often report an immediate improvement in quality of life – even in the hospital."

Dr. William Hiesinger, MD
Lead Surgeon for Stanford’s Hypertrophic Cardiomyopathy Center

Transfer Center and Referral Information

Patients and Families (Self-Referral)

Contact the Adult Cardiac Surgery scheduling department at 650-724-7500

Physicians and Health Care Professionals

Fax a referral to the Adult Cardiac Surgery department at (650) 736-0901.
Contact the Adult Cardiac Surgery scheduling department at (650) 724-7500.

Transfer Center

Phone: 1 (800) 800-1551 (24 hours – 7 days a week)
Fax: (650) 723-6505