What is idiopathic cardiomyopathy?

The term cardiomyopathy refers to a number of diseases that affect the heart. There are four main types of cardiomyopathy: hypertrophic cardiomyopathy, restrictive cardiomyopathy, dilated cardiomyopathy, and arrhythmogenic right ventricular dysplasia, or ARVD. Cardiomyopathy can have several causes. It can be genetic, or it can occur as a result of alcohol and drug abuse, infection with various diseases, hypertension, nutritional deficiency, and even pregnancy. Sometimes, however, cardiomyopathy occurs without a discernible cause, in which case, it is known as idiopathic cardiomyopathy.

Idiopathic dilated cardiomyopathy, considered the most common type of cardiomyopathy, occurs when the heart muscle stretches and thins without any discernible cause. The thinning and stretching of the heart muscle means that the chambers of the heart become larger. Over time, the heart muscle begins to lose its ability to pump blood efficiently. Symptoms may include edema or fluid retention in the ankles, legs, feet, and abdomen; labored breathing; and fatigue. Ultimately, dilated cardiomyopathy can lead to heart failure.

Hypertrophic cardiomyopathy is also common and is known as idiopathic when its cause cannot be determined. In hypertrophic cardiomyopathy, the ventricular walls, and sometimes the walls of the heart's mitral valve, thicken. Eventually, ventricular block can occur, putting undue stress on the heart muscle as it struggles to pump blood through the narrow ventricular passageways. Hypertrophic cardiomyopathy doesn't always lead to ventricular block, but even if it doesn't, the heart loses efficiency. Symptoms of hypertrophic cardiomyopathy can include dizziness, shortness of breath, chest pain, arrhythmia, fainting, and exercise intolerance.

ARVD is possibly the rarest form of idiopathic cardiomyopathy. It is usually found in young adults and adolescent children. In ARVD, necrosis affects the muscle of the right ventricle, and scar tissue grows in place of previously healthy heart muscle tissue. Symptoms can include arrhythmia, fainting, exercise intolerance, and even sudden cardiac arrest.

Idiopathic restrictive cardiomyopathy is similar to ARVD in that it also causes scar tissue to develop instead of healthy heart tissue. This type of cardiomyopathy most often affects the elderly. Scar tissue in the heart is stiffer than healthy muscle tissue, and its presence means the heart can't pump properly. Symptoms include arrhythmia and heart failure.

Idiopathic cardiomyopathy can be treated with medications to lower blood pressure, reduce arrhythmias, prevent blood clots, and slow the heart rate. Open heart surgery may be done to correct heart muscle deformities. A heart transplant may be necessary if the damage to the heart muscle is severe. Surgically implanted devices can help improve heart function and control arrhythmia. A procedure known as alcohol septal ablation can treat thickened ventricles without invasive surgery.

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