Hypertrophic Cardiomyopathy

What Is Hypertrophic Cardiomyopathy?

At University Hospitals Harrington Heart & Vascular Institute, patients with hypertrophic cardiomyopathy (HCM) are managed by diverse medical and surgical disciplines who are all synced into one highly specialized HCM board for the best patient outcomes.

Hypertrophic cardiomyopathy (HCM) is a disease in which the muscle of the heart’s main pumping chamber (the left ventricle) becomes abnormally thick (hypertrophy). This thickening can shrink the size of the pumping chamber and cause the heart to become stiff. As a result, a heart affected by HCM must work harder than normal and may have difficulty pumping oxygen-rich blood out to the rest of the body.

Hypertrophic cardiomyopathy is the most commonly inherited heart condition, affecting about one in 500 people. Many individuals living with the disease don’t know they have it and remain undiagnosed. Although most individuals with HCM can live normal lives, the condition can be serious and even life-threatening for some people.

HCM is most often caused by abnormal genes. The condition usually affects the muscular wall (septum) that separates the two bottom chambers (ventricles) of the heart. HCM can cause:

• Outflow tract obstruction: The thickened septum can result in a narrowing that blocks or reduces blood flow from the left ventricle to the aorta. As a result, the ventricles must pump harder to overcome the blockage.
• Left ventricular stiffness: Stiffness of the left ventricle makes it harder for the heart to relax, reducing the amount of oxygen-rich blood the ventricle can hold and deliver to the organs and muscles of body.
• Mitral valve changes: The mitral valve is one of the four heart valves that keep blood flowing in the correct direction. The valve is located between the two left heart chambers (left atrium and left ventricle). In people with HCM, the mitral valve may strike the thickened septum and cause blood to leak back into the left atrium.
• Cellular changes in the heart muscle: People with HCM have a rearrangement of heart muscle cells. This cellular misalignment can trigger abnormal heart rhythms in some people.

Types of Hypertrophic Cardiomyopathy

There are two types of HCM:

 

Obstructive HCM (OHCM)

Also called hypertrophic obstructive cardiomyopathy (HOCM), this type of HCM occurs when the enlarged septum blocks blood from flowing freely out of the heart to the body (outflow tract obstruction). OHCM accounts for two-thirds of diagnosed cases.

 

Nonobstructive HCM (NHCM)

In nonobstructive HCM, the septum is thickened but does not block blood from flowing out of the heart. However, in nonobstructive HCM, the left ventricle can stiffen, making it harder for the heart to relax while reducing the amount of blood the ventricle can hold and deliver to the body. NHCM accounts for one third of diagnosed cases.

Hypertrophic Cardiomyopathy Symptoms

People with HCM may experience many symptoms or none at all. Common symptoms of HCM include:

• Chest pain
• Shortness of breath and fatigue, especially with exertion
• Fainting or passing out (syncope)
• Heart murmur (whooshing sound between heartbeats that can be detected with a stethoscope)
• Sensation of fast, fluttering or pounding heartbeats (palpitations)
• Abnormal heartbeat (arrhythmia)
• Swelling in the ankles, feet, legs, abdomen or neck

If Left Untreated, What Can Happen to Someone With HCM?

Depending on the severity of the condition, a person with untreated HCM may eventually experience a stroke from atrial fibrillation, develop heart failure, require a heart transplant or experience sudden cardiac death (SCD).

Our Hypertrophic Cardiomyopathy Team

The multidisciplinary HCM board includes top rated specialists in cardiovascular medicine, cardiovascular imaging, electrophysiology, heart failure, cardiac surgery, cardiovascular genetics, interventional cardiology, maternal cardiology and pediatric cardiology. The board meets to formulate an individualized plan of care that is patient specific.