(Cardiomyopathy, Hypertrophic; HCM; Idiopathic Hypertrophic Subaortic Stenosis; Asymmetric Septal Hypertrophy; ASH; HOCM; Hypertrophic Obstructive Cardiomyopathy)
Pronounced: hi-per-TRO-fik car-DEE-o-my-AH-pah-thee
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Definition
Hypertrophic cardiomyopathy, or HCM, is a form of cardiomyopathy, a condition in which the heart muscle thickens. As the muscle thickens, it must work harder to pump blood, and this strains the heart muscle. HCM usually causes only one side of the heart to thicken, making the heart pump unevenly.
There are three main types of cardiomyopathy: dilated, hypertrophic, and restrictive. Hypertrophic cardiomyopathy can be divided into two types: hypertrophic obstructive cardiomyopathy (HOCM) and non-obstructive hypertrophic cardiomyopathy.
In HOCM, the muscle between the two valves of the heart becomes so enlarged that it obstructs the blood flow in the heart. In the non-obstructive form, the enlarged muscle is not large enough to block blood flow.
HCM can occur in people of all ages, but it is usually most severe when it occurs in younger people.
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.
Causes
Causes of HCM include:
- An inherited gene that causes the abnormality
- 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
A risk factor is something that increases your chance of getting a disease or condition. The following factors increase your chance of developing HCM:
- 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 cardiac arrhythmias (abnormal heartbeats). The blocked or reduced blood flow is usually the cause of symptoms like dizziness, fainting, and difficulty breathing. Because blood flow is obstructed or reduced, oxygen can't reach the cells. Reduced blood flow results in insufficient oxygen, which results in many of the symptoms listed above.
Diagnosis
Your doctor will ask about your symptoms and medical history, and perform a physical exam.
Tests may include the following:
- Echocardiography—a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart
- Transesophogeal echocardiogram—takes images of the heart and detects 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
Treatment
Treatment for HCM focuses around controlling symptoms and preventing the onset of complications related to the condition. 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.
Patients with arrhythmia (irregular heartbeat) may require anti-arrhythmic drugs. Blood-thinning medications may also be prescribed.
Surgery
The thickened portion of the heart muscle is cut and removed. This may be needed in patients with 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
This is a procedure in which alcohol is injected into the arteries of the thickened portion of the heart. The injection helps reduce the blockage in the heart and improve blood flow out of the heart.
Implantable-cardioverter Defibrillator (ICD)
This is a device implanted in high-risk patients who may be at heightened risk for sudden death.
Prevention
To help reduce your chance 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:
The Cardiomyopathy Association
http://www.cardiomyopathy.org/index.php?...
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.
Hypertrophic Cardiomyopathy Association
http://www.4hcm.org/WCMS/index.php?overv...
Maron BJ, Nishimura RA, McKenna WJ, et al. Assessment of permanent dual chamber pacing for patients with hypertrophic cardiomyopathy. Circulation. 1999;99:2927-2933.
The Mayo Clinic
http://www.mayoclinic.org/hypertrophic-c...
McCully RB, Nishimura RA, Tajik AJ, Schaff HV, Danielson GK. Extent of clinical improvement after surgical treatment of hypertrophic obstructive cardiomyopathy. Circulation. 1996; 94(3):467-471.
CANADIAN RESOURCES:
British Columbia Ministry of Health
http://bchealthguide.org/kbase/topic/min...
REFERENCES:
Cardiomyopathy. The American Heart Association website. Available at: http://www.americanheart.org/presenter.j.... Accessed June 26, 2007.
DynaMed website. Available at: http://dynamed102.ebscohost.com/Detail.a.... Accessed June 26, 2007.
The HCM Program. St.-Luke's Roosevelt Hospital Center website. Available at: http://www.hcmny.org/whatis/index.html. Accessed June 26, 2007.
Hypertrophic cardiomyopathy. The Cleveland Clinic Heart and Vascular Institute website. Available at: http://www.clevela.... Accessed June 26, 2007.
Hypertrophic cardiomyopathy. Medline Plus Medical Encyclopedia. US National Library of Medicine website. Available at: http://www.nlm.nih.gov/medlineplus/ency/.... Accessed June 26, 2007.
Last reviewed November 2007 by Michael J. Fucci, DO
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