Q: Two acquaintances of mine have had a heart transplant while in their 30s. What kind of heart problem can require a transplant at that early age?
A: Although it is a relatively uncommon form of heart disease, cardiomyopathy is the most common disorder resulting in a heart transplant in young people. Cardiomyopathy is a term used to describe several types of abnormalities of the muscle (myocardium) of the left ventricle, the heart chamber that pumps blood via the aorta to the rest of the body.
In dilated (or congestive) cardiomyopathy, the wall of the left ventricle is thin while the cavity holding blood within the left ventricle is enlarged (or dilated). Viral infections of the myocardium and alcoholism can produce dilated cardiomyopathy, but in the vast majority of cases the cause is unknown.
Hypertrophic cardiomyopathy results from a thickening of the muscle of the left ventricle associated with a reduced size of the ventricular cavity. This form of cardiomyopathy can be inherited.
In restrictive cardiomyopathy, the heart is stiffened by substances like iron or proteins.
In most cases, cardiomyopathy develops slowly and produces no symptoms until far advanced. The type of cardiomyopathy determines, to some extent, the kind of symptoms and the long-term outcome of these disorders.
Poor contraction of the ventricle commonly leads to heart failure with shortness of breath or exertion and swelling of the feet and ankles (edema). The reduced blood supply to the brain and heart can cause dizziness, fainting or chest pain. Sluggish blood flow promotes the formation of blood clots which can travel from their site of formation within the heart to block the blood vessels in the brain and extremities.
Some of the medications used to treat heart failure and rhythm disturbances and to prevent blood clots may improve the symptoms associated with cardiomyopathy. However the poor long-term prognosis in most cases accounts for the high frequency of heart transplants in patients with this disorder.
Dr. Margolis is professor of medicine and biological chemistry at Johns Hopkins School of Medicine.