Tuesday, March 27, 2012

Cardiomyopathies – Heart diseases | Types of Cardiomyopathies

Cardiomyopathies are the heart diseases resulting from a primary abnormality in the myocardium. Features of inflammation are minimal. Cardiomyopathy should be suspected in a young normotensive patient who develops heart failure in the absence of congenital, valvular or ischemic heart disease.

Types of Cardiomyopathies

Dilated (congestive) cardiomyopathy: It is characterized by progressive cardiac hypertophy, dilation and contractile (systolic) dysfunction resulting in failure of ventricle to empty in systole. Most cases develop heart failure. Cause is not detectable in most of the cases. A few cases are associated with:
  • Viral infections e.g conxsakievirus B.
  • Metabolie diseases e.g hypothyroidism hyperthyroidism and thiamine deficiency.
  • Alcoholism.

Hypertrophic Cardiomyopathy
It also referred to as asymmetrical septal hypertrophy and idiopathic hypertrophic subaortic stenosis. This condition is characterized by marked hypertrophy of the ventricular muscles with resistance to diastolic filling. Selective hypertrophy of the septum immediately below the aortic valve, obstructing the left ventricular outflow tract. Both ventricles are diffusely involved in most cases. In about 50% cases the disorder is inherited as an autosomal dominant trait. The interventricular septum is substantially thicker than the free lateral wall of the left ventricle.

Asymmetric hypertrophy is often associated with a significant degree of ventricular outflow obstruction during systole. In this group of patients, the systolic obstruction is caused by abnormal anterior motion of mitral valve leaflet during systole.

Clinical Features: The basic abnormality in hypertrophic cardiomyopathy is an inability to fill a hypertrophic left ventricle. Ejection is forceful but ineffective because the amount of blood in the left ventricle is very small. In addition there is obstruction of the left ventricle outflow. The limitation of cardiac output and a secondary increase in pulmonary venous pressure cause exertional dyspnea. Myocardial ischemia is common and anginal pain is frequent.

Restrictive Cardiomyopathy
It is characterized by a primary disease in ventricular compliance due to fibrosis and stiffness of ventricular walls, resulting in impaired ventricular filling during diastole. Exact cause unknown: myloidosis hemochromatosis and sarcoidosis are involved in some cases.

Clinical Features: The physiologic problem in restrictive cardiomyopathy is a stiff and inelastic ventricle that can be filled only with great effort. Clinically it presents with heart filure and angina.

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