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Diagnosing Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) means “thick heart muscle disease.” In this condition, the walls of the heart’s lower left chamber—the left ventricle—thicken, hindering the heart’s ability to pump blood throughout the body. Left untreated, it can lead to heart failure symptoms, which occur when the heart cannot pump enough blood to meet the body’s needs.

In two-thirds of people with the condition, the ejection of blood from the heart’s main pumping chamber becomes obstructed, causing the heart to work even harder to pump blood. Symptoms can worsen with physical exertion or after meals.

Symptoms and Causes of Hypertrophic Cardiomyopathy

At NYU Langone, our cardiac specialists are experts at diagnosing HCM, which can mimic other cardiac conditions, including mitral valve prolapse, aortic stenosis, and coronary artery disease. Its symptoms can also resemble and be mistaken for those associated with conditions that don’t affect the heart at all, including exercise-induced asthma and panic attacks.

Symptoms of HCM can include shortness of breath, discomfort while exercising, lightheadedness, fainting, heart palpitations, and chest pain with exertion or after meals. Sometimes the condition causes few or no symptoms. As a result, it may go unnoticed until a routine medical examination. A doctor may discover an unusual sound called a heart murmur, or the electrocardiogram may show an abnormal result or an irregular heart rhythm, which can occur as the condition worsens.

Most commonly, the septum—the wall that separates the heart’s left and right chambers—thickens, but any or all of the walls of the heart can be affected. In addition, the condition often elongates the mitral valve, the gateway between the heart’s left atrium, or upper chamber, which receives blood from the lungs, and the left ventricle—the lower chamber—which pumps blood to the body. When this occurs, the mitral valve may participate in obstruction and the left ventricle has to work harder to pump blood and may not empty completely. Sometimes the mitral valve leaks blood, which flows backward instead of forward.

HCM is often an inherited condition. Variants in genes that impact the heart muscle’s growth are found in roughly 40 percent of people with HCM.

The condition can be found in people of all ages. It is especially important to diagnose the condition in young people, particularly athletes, in whom undiagnosed HCM may lead to life-threatening irregular heart rhythms.

To diagnose HCM, your NYU Langone doctor performs a physical exam to check for a heart murmur. They may also conduct one or more diagnostic tests.

Electrocardiogram

An electrocardiogram, or EKG, records the heart’s electrical activity—which triggers the heart to pump blood to the body—to determine the rate, rhythm, and size of the heart. Small, painless electrodes are placed on the chest, wrists, and ankles to send information about the heart’s electrical activity to a machine, which creates a printed graph.

An EKG may detect an abnormal tracing that indicates thickening of the heart muscle or an irregular heartbeat which may be associated with the condition.

Transthoracic Echocardiogram

A transthoracic echocardiogram, which uses sound waves to produce images of the heart, helps your doctor determine the heart’s ability to pump blood and identifies irregularities in the size or shape of the heart. It allows the doctor to visualize the characteristic thickening of the heart walls and can help identify an irregularity in the movement of the mitral valve’s leaflets that causes obstruction, which is called systolic anterior motion.

During this test, a technician presses a handheld device called a transducer on your chest to send signals from your heart to a computer, which converts them into a moving image that your doctor can view and interpret.

Stress Exercise Transthoracic Echocardiogram

If an echocardiogram reveals thickened walls in the left ventricle but does not identify any irregularities in the mitral valve leaflets’ motion, your doctor may perform a stress exercise transthoracic echocardiogram.

During the test, the doctor creates images of the heart at rest. Then, they ask you to walk or, if you are healthy enough, to run on a treadmill for several minutes until you wish to stop. After running, a transthoracic echocardiogram is used to capture images of the heart, helping your doctor determine its response to exercise.

Exercise can lead to systolic anterior motion, in which the mitral valve obstructs the left ventricle’s ejection of blood. The test allows your doctor to determine the precise condition that is limiting your ability to exercise. Because exercise after eating is often challenging for people with HCM, we may ask you to eat a moderate meal before the exercise portion of the test.

Transesophageal Echocardiogram

A transesophageal echocardiogram provides sharper images of obstructions in the heart than a regular echocardiogram. This is because the ultrasound probe—which is inserted through the mouth and into the esophagus—can be placed closer to the heart.

For your comfort, you may be given a mild sedative and pain medication through a vein with intravenous infusion. The test takes 20 to 30 minutes to complete.

MRI Scans

An MRI uses a magnetic field and radio waves to create clear and precise images of the heart. It can help your doctor determine the extent of the thickening of the heart’s walls and identify any scarring, or fibrosis. Fibrosis is important to detect because it may be associated with shortness of breath, exercise intolerance, and irregular heart rhythms. Doctors may inject a contrast agent, or dye, into a vein to enhance the MRI images. MRI images are complimentary to echocardiographic images: each provides information the other cannot.

Coronary Catheterization and Angiogram

In a coronary catheterization and angiogram, X-rays create cross-sectional images of the heart to help your doctor determine how well the organ is pumping blood to the rest of the body and whether the mitral valve is leaking. It is performed using local anesthesia and sedation.

This test is also used to measure differences in pressure in the left ventricular outflow tract, through which blood flows to the aorta. The higher the pressure difference, the greater the obstruction. A coronary catheterization and angiogram test also helps measure the volume of blood pumped per minute.

In this procedure, the doctor places a small, hollow tube called a catheter into a vein in the arm or groin and advances it through the aorta to the heart. They use a fluoroscope, which provides real-time X-ray images, for guidance in advancing the catheter to the heart’s chambers.

An angiogram of the left ventricle and coronary arteries, which supply blood to the heart, is performed during the same procedure. The doctor injects a contrast agent, or dye, into the catheter. It flows to the arteries to highlight any blockages. This helps the doctor to identify other problems that may require treatment. Since both coronary artery narrowing and HCM can cause chest pressure, and angiogram may help your doctor determine if your symptoms are caused by HCM alone or also by coronary artery disease.

After the procedure, the doctor removes the catheter and closes the insertion site with stitches.

Genetic Testing

Because HCM is often inherited, your doctor may recommend genetic testing. This might include an echocardiogram and an EKG for your first-degree relatives, including siblings, children, and, possibly, your parents.

Your doctor may recommend a DNA analysis, which is a genotype test. In this test, a technician draws blood, which is analyzed in a laboratory for certain genetic variants that signify a predisposition to the condition. Alternatively, you may be asked to provide a sputum sample by coughing deeply to produce a sample of mucus from the lower airways. Our genetic experts provide counseling regarding all test results and answer questions. We believe this counseling is essential for you to understand the meaning of genetic testing for you and your family.

Our Research and Education in Hypertrophic Cardiomyopathy

In addition to patient care, our doctors are also involved in scientific research and in providing education for medical professionals.