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Hypertrophic Cardiomyopathy—Adult by Diana Kohnle

Definition

Hypertrophic cardiomyopathy, or HCM, is a form of cardiomyopathy . This is a condition in which the heart muscle thickens due to genetic problems with the muscle’s structure. As the muscle thickens, it must work harder to pump blood, which strains the heart muscle. Sometimes, the thickened muscle gets in the way of the blood leaving the heart and causes a blockage. This blockage can cause the neighboring heart valve, called the mitral valve, to become leaky. HCM can cause uneven muscle growth which can cause the heart to pump in a disorganized way. Rarely, it can cause abnormal heart rhythms that can even be fatal.

There are three main types of cardiomyopathy:

Dilated
Hypertrophic—can be divided into two types:
- Hypertrophic obstructive cardiomyopathy (HOCM)—the muscle between the two valves of the heart becomes so enlarged that it obstructs the blood flow in the heart
- Non-obstructive hypertrophic cardiomyopathy—non-obstructive form, the enlarged muscle is not large enough to block blood flow
Restrictive

HCM can occur in people of all ages. But, it is usually most severe when it occurs in younger people. The diagnosis is only made in people who do not have other causes of cardiomyopathy (eg, amyloidosis , sarcoidosis , coronary or valvular heart disease, etc.)

Those with HCM are at an increased risk of sudden death. However, many individuals with HCM live a normal, healthy life with very few symptoms.

Normal Heart and Heart With Hypertrophic Cardiomyopathy

Causes

Causes of HCM include:

A gene that causes the abnormal structure of the heart muscle. It can be inherited or can happen from changes in the genes over time.
A defective gene that controls growth of the heart muscle
A viral infection

In people over age 60, HCM is likely to be caused by or related to high blood pressure .

Risk Factors

These factors increase your chance of developing this condition. Tell your doctor if you have any of these risk factors:

Having a family member with HCM
Being over age 60 and having hypertension

Symptoms

Symptoms include:

Chest pain
Fainting, particularly during exercise
Dizziness or lightheadedness, particularly following exercise
Heart palpitations
Shortness of breath or difficulty breathing
General fatigue
Tiring easily during exercise or activity
Shortness of breath when lying down

These symptoms can be caused by some of the side effects of the condition, including arrhythmias (abnormal heart beats). The blocked or reduced blood flow is usually the cause of symptoms like dizziness, fainting, and difficulty breathing.

Diagnosis

Your doctor will ask about your symptoms and medical history, and perform a physical exam.

Tests may include the following:

Stress test —tests how the body responds to exercise, which can help in detecting heart and lung problems
Echocardiography —uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart
Transesophageal echocardiogram —images of the heart are taken to detect abnormalities
Heart monitor—a portable electrocardiogram (ECG) records continuous heart activity usually over a 24-72 hour period to determine regularity of the heartbeat
Heart catheter—a catheter is inserted into an artery in the groin area and threaded to the heart chambers
- An x-ray machine shows real-time images of your body as a dye is injected through the catheter. This allows angiograms (photos) to be taken of the blood vessels and the heart.
Blood tests
Chest x-ray —uses radiation to take a picture of structures inside the body, especially bones.

Treatment

Treatment focuses on controlling symptoms and preventing complications. Talk with your doctor about the best treatment plan for you. Treatment options include:

Medications

Medications may be used to help maintain proper and regular heart function. These may include beta-blockers and calcium channel blockers.

If you have an arrhythmia, you may need anti-arrhythmic drugs. You may also need blood-thinning medication.

Surgery

The thickened portion of the heart muscle is cut and removed. This may be needed if you have a severely blocked blood flow from the heart.

If the mitral valve is leaking, surgery may also be done to repair or replace the mitral valve.

Alcohol Septal Ablation

Alcohol is injected into the arteries of the thickened portion of the heart. This helps to reduce the blockage in the heart and improve blood flow out of the heart.

Implantable Cardioverter Defibrillators (ICD)

This ICD is implanted if you are at heightened risk for sudden death.

Prevention

To help reduce your chances of getting HCM, take the following steps:

If you have a family member who has been diagnosed with HCM—you and other family members should be screened for the condition
If family history puts you at higher risk for HCM—regular echocardiograms may reduce the risk of death or complications from HCM
If you have high blood pressure—take medications and follow other instructions as directed by your physician.

RESOURCES:

American Heart Association http://www.americanheart.org/
Cardiomyopathy Association http://www.cardiomyopathy.org/

CANADIAN RESOURCES:

Canadian Cardiovascular Society http://www.ccs.ca/
Heart and Stroke Foundation of Canada http://ww2.heartandstroke.ca/

References:

American Heart Association. Cardiomyopathy. American Heart Association website. Available at: http://www.americanheart.org/presenter.jhtml?identifier=4468 . Accessed June 26, 2007.
Cleveland Clinic Heart and Vascular Institute. Hypertrophic cardiomyopathy. The Cleveland Clinic Heart and Vascular Institute website. Available at: http://www.clevelandclinic.org/heartcenter/pub/guide/disease/hcm/default.htm . Accessed June 26, 2007.
DynaMed Editorial Team. Hypertrophic cardiomyopathy. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php . Updated October 25, 2010. Accessed November 5, 2010.
Erwin JP, Nishimura RA, et al. Dual chamber pacing for patients with hypertrophic obstructive cardiomyopathy: a clinical perspective in 2000. Mayo Clin Proc . 2000;75:173-180.
The HCM Program. St. Luke's Roosevelt Hospital Center website. Available at: http://www.hcmny.org/whatis/index.html . Accessed June 26, 2007.
Maron BJ, Nishimura RA, McKenna WJ, et al. Assessment of permanent dual chamber pacing for patients with hypertrophic cardiomyopathy. Circulation . 1999;99:2927-2933.
Mayo Clinic. Hypertrophic cardiomyopathy. Mayo Clinic website. Available at: http://www.mayoclinic.com/health/hypertrophic-cardiomyopathy/DS00948 . Updated March 25, 2009. Accessed November 5, 2010.
McCully RB, Nishimura RA, Tajik AJ, Schaff HV, Danielson GK. Extent of clinical improvement after surgical treatment of hypertrophic obstructive cardiomyopathy. Circulation . 1996;94:467-471.

Last reviewed September 2012 by Michael J. Fucci, DO

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