Cardiomyopathy (Heart Muscle Disease) Types, Causes, Symptoms

What is Cardiomyopathy?

Cardiomyopathy is disease of the heart muscle (myocardium). There are several types of cardiomyopathies but all affect heart functioning to varying degrees. Cardiomyopathy is a weakening of the heart often associated with enlargement and is sometimes referred to by common names like enlarged heart disease or thickened heart muscle disease.

How does cardiomyopathy occur?

The heart is a muscular pump and its wall is made up of three layers – the endocardium (inner), myocardium (middle) and epicardium (outer). The middle myocardium is a thick muscle layer that contracts and relaxes in order to pump blood through the heart. In order for the heart to continue working efficiently, the muscle must be able to push out enough blood to meet the body’s needs and the heart wall has to be flexible enough to accommodate the filling and emptying.

Cardiomyopathies may occur for a number of reasons which leads to changes in the heart muscle layer (myocardium). The heart muscle may thicken,  portions of the heart (chambers) may enlarge significantly or the walls of the heart become inflexible. Despite the enlargement of the heart and thickening of the myocardium, the heart does not function optimally and eventually fails. A primary cardiomyopathy arises within the heart muscle (myocardium) and is confined to it while with secondary cardiomyopathy, the disease is a consequence of some other underlying disorder or systemic illness.

Types of Cardiomyopathy

There are three main types of cardiomyopathies :

  1. Dilated cardiomyopathy, also known as congestive cardiomyopathy, is an enlargement of the heart, particularly the left ventricle, with an inability of the heart to pump out blood in an efficient manner.
  2. Hypertrophic cardiomyopathy is a thickening of the heart muscle with stiffness and reduced cardiac output.
  3. Restrictive cardiomyopathy is a stiffening of the ventricle walls with an inability of the ventricle to stretch and fill properly.

Causes of Cardiomyopathy

There are various causes of each type of cardiomyopathy. A large number of cases, especially with restrictive cardiomyopathy, occur for no known reason (idiopathic). Other more common causes of cardiomyopathy includes :

  • Chronic hypertension (high blood pressure)
  • Coronary artery disease
  • Myocardial infarction / ischemia
  • Myocarditis (viral)
  • Substance abuse – alcohol, cocaine
  • Medication – antidepressants, chemotherapy
  • Metabolic disorders – thyroid disease, diabetes mellitus

Signs and Symptoms of Cardiomyopathy

Despite the pathophysiological difference among the main types of cardiomyopathy, the signs and symptoms are often the same. This includes :

  • Shortness of breath
  • Swelling, particularly of the legs
  • Abnormal heart rhythm (arrhythmia)

Other signs and symptoms may be specific to or more prominent in certain types of cardiomyopathy. This includes :

  • Chest pain
  • Palpitations
  • Abnormal heart sounds (murmurs)
  • Dizziness and/or fainting