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Cardiomyopathy

Cardiomyopathy means abnormal heart muscle. There are various types of cardiomyopathy. Sometimes the condition appears suddenly, so it is called acute. In other cases the condition has been present for many years or even since birth (congenital) and therefore is termed chronic. Often it can be difficult to determine how long the cardiomyopathy has been present, as sometimes it is not diagnosed until it leads to heart failure.

There are three main types of non-inflammatory cardiomyopathy:

Hypertrophic cardiomyopathy is a disease that causes abnormal thickening (hypertrophy) of the heart muscle. The muscle can be thickened in such a way that it obstructs blood flow out of the heart (hypertrophic obstructive cardiomyopathy or HOCM). In many cases of hypertrophic cardiomyopathy there is a genetic cause, so that if one member of the family is diagnosed with it other biological family members should also be evaluated. The importance of diagnosing this condition is that it can cause sudden, life-threatening rhythm abnormalities that may be associated with strenuous exercise. Therefore, people with this abnormality are often restricted from competitive sports or strenuous activity and are treated with medications known as beta blockers. There is no definitive cure for hypertrophic cardiomyopathy, though surgeries or other procedures are sometimes performed to remove muscle that is causing obstruction. Heart transplantation may be required if symptoms cannot be controlled.

Restrictive cardiomyopathy is when the heart muscle cannot relax normally between heartbeats, so blood cannot easily get into the ventricles that pump it throughout the body. When blood cannot get into the ventricles it backs up, first into the atria, causing them to enlarge (increasing the risk of rhythm abnormalities and clot formation). The blood then backs up into other places such as the lungs (with left ventricular restriction) or more commonly into the body, causing swelling of the extremities or liver enlargement. It may also back up into other organs, preventing them from functioning normally.  There is no medical treatment for restrictive cardiomyopathy other than controlling the symptoms. Heart transplantation is frequently required as the only effective treatment.

Dilated cardiomyopathy is the most common type of cardiomyopathy and has many causes. It can be the result of a genetic abnormality, congenital heart defect, damage from medicines such as chemotherapy, damage from drug use (such as alcohol or cocaine), damage from a prior infection or inflammation (myocarditis), damage from prior heart attacks or coronary artery abnormalities, and more. In the case of dilated cardiomyopathy the heart is usually greatly enlarged and does not pump very well because the muscle is weakened. The extent of this weakness may vary. Symptoms also vary and depend on how well or how poorly the heart functions and the presence of congestive heart failure.

Causes

A cardiomyopathy can occur at birth or later in life due to genetic abnormalities in the heart muscle (familial cardiomyopathy) or other factors while the fetus is developing (congenital cardiomyopathy). It is classified by cause into various groups or types of cardiomyopathy. The first concerns whether there is myocarditis, or inflammation of the heart. The causes of myocarditis can be infectious (viral, bacterial, etc.), or noninfectious (Kawasaki disease, juvenile rheumatoid arthritis and other collagen vascular diseases). Myocarditis can also be caused by an infection that indirectly leads to inflammation of the heart (e.g. rheumatic fever).

Symptoms

The symptoms of cardiomyopathy depend on whether heart failure is occurring. There may be muscle damage or abnormal muscle (cardiomyopathy), but the heart may be able to compensate for the abnormality well enough that no symptoms exist during everyday life. Often, cardiomyopathy symptoms only appear with stress or under special circumstances, making it difficult to diagnose. Therefore, cardiomyopathy presents a spectrum of disease, with some people having symptoms only with extreme exertion and others having symptoms at rest.

The symptoms, if they occur, could be a rhythm abnormality, fatigue, lightheadedness or fainting, or swelling of the body or lungs. The latter occurs if the blood is backed up from right ventricular failure or left ventricular failure (see congestive heart failure). Unfortunately, the first symptom can also be sudden death due to abnormal heart rhythm.

The exact symptoms depend on the type of cardiomyopathy (hypertrophic, restrictive or dilated) and severity.

Treatment

Treatment depends on the type and severity of cardiomyopathy, but in most cases the goal is to manage the symptoms. Some of the options for each of the different types of cardiomyopathy are described above. Treatment is constantly evolving as we learn more about cardiomyopathies from clinical and laboratory research, and newer drugs and modalities are being used all the time to treat these conditions.

Long-term Effects

This depends on the type and severity of the cardiomyopathy. Heart transplantation is a universal treatment for all the types of cardiomyopathy, but it is not always necessary. In fact, heart transplantation can often lead to other serious problems such as infection or rejection. This is why medical treatment for most types of cardiomyopathy is attempted first.

In general, with the different treatment options available for cardiomyopathy the outlook is good, though life expectancy may be shortened. Quality of life will depend on the severity of the underlying cardiomyopathy and can usually be improved with heart transplantation if medical treatment of the cardiomyopathy is unsuccessful.

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