Q. Explain Restrictive cardiomyopathy?

It is a systemic or idiopathic disorder of the myocardium with clinical and hemodynamic features of diastolic dysfunction, closely simulating constrictive pericarditis. Restrictive cardiomyopathes could be myocardial or endomyocardial. The former could be noninfiltrative (e.g., idiopathic or familial), infiltrative (e.g., amyloidosis) or storage (e.g., hemochromatosis). The endomyocardial group could be obliterative (e.g., Endomyocardial Fibrosis) or nonobliterative (e.g., radiation, drugs).

Clinical Menifestation

The symptoms are those of pulmonary and systemic congestion viz. Dyspnoea, nocturnal dyspnoea, ankle edema, abdominal discomfort. The findings are those of raised filling pressures on two sides of heart - Raised JVP with prominent X and Y descent. (Y is more prominent than X), enlarged tender liver and ankle edema, and also signs of pulmonary venous congestion viz. S3, rales over both lungs.

Electrocardiography

It is always abnormal. LBBB is common but RBBB also can occur. There may be cardiac arrhythmias. Atrial fibrillation is common. Low voltage occurs in cardiac amyloidosis.

X-Ray Chest

There are two major features (1) Absence of cardiomegaly (2) signs of pulmonary venous hypertension.

2D Echocardiography

The heart is only minimally dilated and there is no thickening of the myocardium in idiopathic causes, but may be thickened in infiltrative disorders. Both atria are enlarged. The filling pattern on Doppler may simulate that of constrictive pericarditis, but early rapid filling is more rapid in some. Prominent E-wave suggests that. It also has severely reduced deceleration time indicative of raised left atrial pressure. LV thickness is usually less than 1.7cm. Ventricular systolic function is normal. LVED volume is not more than 110 ml/m2 and LV end diastolic dimension in not more than 6 cm.

In endomycardial fibrosis, there is diminution of ventricular volumes, frequently associated with complete obliteration of apices of both ventricles.