Chapter 39 Cardiomyopathies and dissecting haematoma of the aorta
The term cardiomyopathy does not have a precise definition, but it is generally used to describe three conditions: hypertrophic, dilated and restrictive cardiomyopathy. Dilated cardiomyopathy is the commonest.
The definition of dilated cardiomyopathy (also known as congestive cardiomyopathy) is progressive cardiac hypertrophy with dilatation affecting all chambers and associated with progressive systolic dysfunction. It is caused by diffuse damage to the myocardium and can have a number of aetiologies, including:
The systolic dysfunction produces heart failure, which is often fatal. In some cases, mural thrombi form in the flabby cardiac chambers. If they break off, they give rise to embolic complications.
This condition is characterized by a hypertrophic left ventricle that can contract strongly, but it is stiff and diastolic filling is impaired. This stiffness is more precisely described as reduced ventricular compliance. A number of different genetic defects can produce this condition; the genes involved code for a variety of sarcomeric proteins. Although some cases arise sporadically, approximately half of patients inherit the condition as an autosomal dominant trait with variable penetrance and expression. There are a number of clinical features (Fig. 3.39.1):