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A.D.A.M. Medical Encyclopedia [Internet]. Atlanta (GA): A.D.A.M.; 2013.

A.D.A.M. Medical Encyclopedia.

Hypertrophic cardiomyopathy

Cardiomyopathy - hypertrophic (HCM); IHSS; Idiopathic hypertrophic subaortic stenosis; Asymmetric septal hypertrophy; ASH; HOCM; Hypertrophic obstructive cardiomyopathy

Last reviewed: May 13, 2014.

Hypertrophic cardiomyopathy (HCM) is a condition in which the heart muscle becomes thick. Often, only one part of the heart is thicker than the other parts. 

The thickening can make it harder for blood to leave the heart, forcing the heart to work harder to pump blood. It also can make it harder for the heart to relax and fill with blood.

Causes

Hypertrophic cardiomyopathy is a condition that is most often passed down through families (inherited). It is thought to result from defects in the genes that control heart muscle growth.

Younger people are likely to have a more severe form of hypertrophic cardiomyopathy. However, the condition is seen in people of all ages.

Symptoms

Some people with the condition may have no symptoms. They may first find out they have the problem during a routine medical exam.

In many young adults, the first symptom of hypertrophic cardiomyopathy is sudden collapse and possible death. This can be caused by highly abnormal heart rhythms (arrhythmias). It may also be due to a blockage that prevents the outflow of blood from the heart to the rest of the body.

Common symptoms include:

Exams and Tests

The health care provider will perform a physical exam and listen to the heart and lungs with a stethoscope. Signs may include:

The pulse in your arms and neck will also be checked. The doctor may feel an abnormal heartbeat in the chest.

Tests used to diagnose heart muscle thickness, problems with blood flow, or leaky heart valves (mitral valve regurgitation) may include:

Blood tests may be done to rule out other diseases.

Close family members of people who have been diagnosed with hypertrophic cardiomyopathy may be screened for the condition.

Treatment

Always follow your doctor's advice about exercise if you have hypertrophic cardiomyopathy. You may be told to avoid strenuous exercise. Also, see your doctor for regularly scheduled checkups.

If you have symptoms, you may need medicines such as beta-blockers and calcium channel blockers to help the heart contract and relax correctly. These drugs may relieve chest pain or shortness of breath when exercising.

People with arrhythmias may need treatment, such as:

  • Medicines to treat the abnormal rhythm
  • Blood thinners to reduce the risk of blood clots (if the arrhythmia is due to atrial fibrillation)
  • A permanent pacemaker to control the heartbeat
  • An implanted defibrillator that recognizes life-threatening heart rhythms and sends an electrical pulse to stop them. Sometimes a defibrillator is placed, even if the patient has not had an arrhythmia but is at high risk for a deadly arrhythmia (for example, if the heart muscle is very sick or the patient has a relative who has died suddenly).

When blood flow out of the heart is severely blocked, symptoms can become severe. An operation called surgical myectomy may be done. In some cases, patients may be given an injection of alcohol into the arteries that feed the thickened part of the heart (alcohol septal ablation). People who have this procedure often show much improvement.

You may need surgery to repair the heart's mitral valve if it is leaking.

Outlook (Prognosis)

Some people with hypertrophic cardiomyopathy may not have symptoms and will have normal lifespan. Others may get worse slowly or quickly. In some cases, the condition may develop into dilated cardiomyopathy.

People with hypertrophic cardiomyopathy are at higher risk for sudden death than people without the condition. Sudden death can occur at a young age.

There are different types of hypertrophic cardiomyopathy, which have different prognoses. The outlook may be better when the disease occurs in elderly individuals or when there is a particular pattern of thickness in the heart muscle.

Hypertrophic cardiomyopathy is a well-known cause of sudden death in athletes. Almost half of deaths due to this condition happen during or just after some type of physical activity.

When to Contact a Medical Professional

Call your health care provider if:

References

  1. Maron BJ. Hypertrophic cardiomyopathy. Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. St. Louis, MO: WB Saunders; 2011:chap 69.

Review Date: 5/13/2014.

Reviewed by: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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Copyright © 2013, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only — they do not constitute endorsementscof those other sites. © 1997–2011 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Copyright © 2013, A.D.A.M., Inc.

What works?

  • Pacing for drug‐refractory or drug‐intolerant Hypertrophic cardiomyopathyPacing for drug‐refractory or drug‐intolerant Hypertrophic cardiomyopathy
    Hypertrophic cardiomyopathy (HCM) is a genetic disease with an autosomal‐dominant inheritance, which can cause obstruction in the left ventricle outflow tract. This obstruction can lead to a variety of symptoms like dyspnoea, chest pain, syncope and palpitations. The prevalence of HCM in the general population, as determined from echocardiographic studies in the United States, Japan, and China, has ranged from 0.16 to 0.29 percent. Treatment options for HCM ranges from drugs to surgery with each having its own limitations. Active cardiac pacing was suggested as a treatment option in some trials. We conducted this review to assess the available evidence on the effects of active pacing in drug‐refractory or drug‐intolerant HCM patients. Five studies (reported in 10 papers) were found to be relevant. However, three of the five studies provided un‐usable data. Thus data from only two studies (reported in seven papers) with 105 participants was included for this review. There was insufficient data to compare results on all‐cause mortality, cost effectiveness, exercise capacity, Quality of life and Peak O2 consumption. There was no difference in exercise capacity when comparing active pacing versus placebo pacing. However left ventricular outflow tract obstruction decreased significantly in the active pacing group compared to placebo. New York Heart Association functional class increased in the active pacing group compared to the placebo group and this was also observed when comparing active pacing versus trancoronary ablation of septal hypertrophy. Interpretation of these data needs to be cautious because existing data is derived from small trials at high risk of bias, which concentrate on physiological measures. Their results are inconclusive. Further large and high quality trials with more appropriate outcomes are warranted.
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Figures

  • Heart, section through the middle.
    Heart, front view.
    Hypertrophic cardiomyopathy.

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