is an ongoing disease process that damages the muscle wall of the lower chambers of the heart. Hypertrophic cardiomyopathy is a form of cardiomyopathy in which the walls of the heart's chambers thicken abnormally. Other names for hypertrophic cardiomyopathy are idiopathic hypertrophic subaortic stenosis and asymmetrical septal hypertrophy.
Hypertrophic cardiomyopathy usually appears in young people, often in athletes. For this reason it is sometimes called athletic heart muscle disease. However, people of any age can develop hypertrophic cardiomyopathy. Often there are no symptoms of hypertrophic cardiomyopathy. Sudden death
can occur, caused by a heart arrhythmia. The American Heart Association reports that 36% of young athletes who die suddenly have probable or definite hypertrophic cardiomyopathy.
Hypertrophic cardiomyopathy is the result of abnormal growth of the heart muscle cells. The wall between the heart's chambers (the septum) may become so thickened that it blocks the flow of blood through the lower left chamber (left ventricle). The thickened wall may push on the heart valve between the two left heart chambers (mitral valve), making it leaky. The thickened muscle walls also prevent the heart from stretching as much as it should to fill with blood.
Causes and symptoms
The cause of hypertrophic cardiomyopathy is not known. In about one-half of cases, the disease is inherited. An abnormal gene has been identified in these patients. In cases that are not hereditary, a gene that was normal at birth may later become abnormal.
Often people with hypertrophic cardiomyopathy have no symptoms. Unfortunately, the first sign of the condition may be sudden death caused by an abnormal heart rhythm. When symptoms do appear, they include shortness of breath
on exertion, dizziness
, fainting, fatigue, and chest pain
The diagnosis is based on the patient's symptoms (if any), a complete physical examination
, and tests that detect abnormalities of the heart chambers. Usually, there is an abnormal heart murmur that worsens with the Valsalva maneuver. The electrocardiogram (ECG), which provides a record of electrical changes in the heart muscle during the heartbeat, also is typically abnormal.
Sometimes, a routine chest x ray
may show that the heart is enlarged. Echocardiography
, a procedure that produces images of the heart's structure, is
This illustration shows hypertrophic muscle in the heart. The abnormally thick wall of muscle prevents the chambers from stretching to fill up with blood, making the heart less efficient. The extra tissue may also push on the heart valve (center), causing it to leak.
(Illustration by Bryson Biomedical Illustrations, Custom Medical Stock Photo. Reproduced by permission.)
usually done. These images can show if the heart wall is thickened and if there are any abnormalities of the heart valves.
Treatment of hypertrophic cardiomyopathy usually consists of taking medicines and restricting strenuous exercise
. Drugs called beta blockers and calcium channel blockers
are usually prescribed. Beta blockers
reduce the force of the heart's contractions. Calcium channel blockers can help improve the flexibility of the heart muscle walls, allowing them to stretch more. Antiarrhythmic drugs may also be given to prevent abnormal heart rhythms.
Patients with hypertrophic cardiomyopathy are also told to avoid strenuous exercise to reduce the risk of passing out or sudden death.
In some cases, if the medications do not help relieve symptoms, surgery may help. In an operation called myotomy-myectomy a piece of the septum is removed to improve blood flow through the heart chamber.
Some patients have pacemakers
and/or defibrillators implanted to help control the heart rate and rhythm. Pacemakers and defibrillators provide electrical impulses to the heart, which can return the heart beat to a normal rhythm.
If these treatment methods fail and a patient develops heart failure, a heart transplant may be necessary.
Some people with hypertrophic cardiomyopathy may not have obstructed blood flow and may never experience symptoms. Others may only experience mild symptoms. With treatment, symptoms may improve. In some patients, the disease may progress to heart failure
While hypertrophic cardiomyopathy cannot be prevented, precautionary measures may prevent sudden deaths. Anyone planning to take part in a program of strenuous competitive exercise should have a checkup by a physician first. A physical examination before athletic participation can usually, but not always, detect conditions like hypertrophic cardiomyopathy. Anyone who experiences symptoms of shortness of breath, tiredness, or fainting with exercise should see a physician.
American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. http://www.americanheart.org.
National Heart, Lung and Blood Institute. PO Box 30105, Bethesda, MD 20824-0105. (301) 251-1222. http://www.nhlbi.nih.gov.
Texas Heart Institute. Heart Information Service. PO Box 20345, Houston, TX 77225-0345. http://www.tmc.edu/thi.
— The heart valve that controls blood flow between the heart's left upper chamber (atrium) and left lower chamber (ventricle).
— The muscular wall dividing the left and right heart chambers.
a general diagnostic term designating primary myocardial disease.
a congestive cardiomyopathy resulting in cardiac enlargement and low cardiac output occurring in chronic alcoholics
; the heart disease in beriberi
(thiamine deficiency) is also associated with alcoholism.
a syndrome characterized by cardiac enlargement, especially of the left ventricle, myocardial dysfunction, and congestive heart failure
an increase in heart muscle weight, particularly of the left ventricle and often involving the interventricular septum; it may affect the flow of blood from an atrium into the ventricle or out from the ventricle. This type of cardiomyopathy is frequently associated with idiopathic hypertrophic subaortic stenosis
. Called also asymmetrical septal hypertrophy
infiltrative cardiomyopathy myocardial disease resulting from deposition in the heart tissue of abnormal substances, as may occur in amyloidosis, hemochromatosis, and other disorders.
primary cardiomyopathy that in which the basic pathologic process involves the myocardium itself and not other cardiac structures; the condition is of unknown etiology and not part of a disease affecting other organs.
restrictive cardiomyopathy a form in which the ventricular walls are excessively rigid, impeding ventricular filling; it is marked by abnormal diastolic function but normal or nearly normal systolic function.
secondary cardiomyopathy any form that is due to another cardiovascular disorder or is a manifestation of a systemic disease such as sarcoidosis.
hypertrophic cardiomyopathy Abbreviation: HCM
An autosomal dominant cardiomyopathy marked by excessive and disorganized growth of myofibrils, impaired filling of the heart (diastolic dysfunction), a reduction in the size of ventricular cavities, and, often, ventricular arrhythmias and sudden death. Examination of the heart by echocardiography or other modalities may show the enlargement of the heart to be most pronounced in the interventricular septum. Hypertrophy in that location may limit the flow of blood (and increase pressure gradients) from the left ventricle to the aorta. Abnormal anterior motion of the mitral valve during systole also may be found. These two findings are often designated on echocardiographic reports of patients with HCM by the abbreviation ASH-SAM (asymmetric septal hypertrophy–systolic anterior motion
[of the mitral valve]). Other forms of HCM may affect only the cardiac apex or cause diffuse enlargement of the heart muscle. The mass of the left ventricle in HCM is > 500 g. See: illustration
Symptoms and Signs
Although patients may be asymptomatic for many years, they commonly report shortness of breath (particularly on exertion), fatigue, atypical chest pain (at rest and after meals), orthopnea, dizziness, and other symptoms of congestive heart failure after the heart muscle markedly enlarges. An S4 and a harsh crescendo-decrescendo systolic murmur, best heard at the left lower sternal border, may be present. Ventricular arrhythmias are common and may result in palpitations, syncope, or sudden death.
Drug therapies include beta blocking and calcium channel blocking drugs (such as verapamil) to slow heart rate, control arrhythmias, and reduce myocardial oxygen demand. Anticoagulants and antiarrhythmic agents are also occasionally used. For patients with marked enlargement of the ventricular septum and high outflow tract pressure gradients (> 50 mm Hg), surgical removal of the enlarged muscle or ablation often produces favorable improvements in exercise tolerance and breathing.
Strenuous physical exercise should be discouraged because it may produce breathlessness, presyncope, or frank loss of consciousness. If applicable, the patient should be encouraged to lose weight, stop smoking, and limit alcohol intake. An implanted cardioverter/defibrillator (ICD) may be required. The patient should be advised to report symptoms of chest pain, prolonged dyspnea, or syncope promptly. First-degree relatives of those affected should be referred for evaluation.
a general diagnostic term designating primary myocardial disease of unknown cause.
a dilated cardiomyopathy, believed to be inherited, is seen in adult Boxers that show syncope, episodic weakness, arrhythmias, and left or biventricular heart failure.
a syndrome characterized by cardiac enlargement, especially of the left ventricle, poor myocardial contractility, and congestive heart failure. Occurs most commonly in young to middle-aged dogs of the large and giant breeds with rapidly developing signs of biventricular failure, atrial fibrillation and occasionally systolic murmurs. Cats usually show acute signs of cardiac failure with pleural effusion but not ascites, and sometimes thromboembolism. Called also dilated cardiomyopathy.
a distinctive cardiomyopathy is seen in Doberman pinscher dogs, often presenting as an acute pulmonary edema, cardiogenic shock and sometimes sudden death.
occurs most commonly in cats, sometimes secondary to hyperthyroidism
, occasionally in dogs and rarely in cattle in association with generalized glycogenosis
. There is myocardial hypertrophy, primarily in the left ventricle and ventricular septum, resulting in increased resistance to filling and sometimes an outflow obstruction. In cats there is often an associated aortic thromboembolism.
myocardial disease secondary to deposition in the heart tissue of abnormal substances such as amyloid or neoplastic infiltration.
occurs in calves and probably in the other species. In calves it causes death due to acute heart failure up to the age of 3 months. Recorded in polled Hereford and Japanese black cattle. There may be a brief period of dyspnea and blood-stained frothy nasal discharge before death. Myocardial degeneration is obvious at necropsy.
in the subclinical stage, but detectable with echocardiography and ambulatory electrocardiographic recording methods.
impaired left ventricular compliance reduces ventricular filling. Uncommon in animals but seen most often in cats, caused by endomyocardial fibrosis or abnormal left ventricular moderator bands. Called also obliterative cardiomyopathy.