Restrictive cardiomyopathies

Restrictive cardiomyopathies

Abnormal diastolic function is the hallmark in restrictive cardiomyopathies. There is a rigid ventricular wall with impaired ventricular filling and there is some functional resemblance to constrictive pericarditis. The differentiation of restrictive cardiomyopathy from operable constrictive pericarditis is important. The two conditions may co-exist in a post irradiation situation or after cardiac transplantation. Radiation can cause both constriction and restriction, while cardiac transplantation can lead to constrictive pericarditis as a sequelae of post cardiotomy syndrome. Cardiac transplant rejection can manifest with restrictive physiology.

Classification RCM

Myocardial diseases

1. Infiltrative: Amyloidosis, sarcoidosis, Gaucher’s disease and Hurler’s disease
2. Non Infiltrative: Idiopathic, scleroderma
3. Storage Disease: Hemochromatosis, Fabry’s disease and glycogen storage disorders

Endomyocardial diseases

1. Endomyocardial fibrosis (EMF)
2. Hypereosinophilic syndrome
3. Carcinoid syndrome
4. Metastatic malignancies
5. Radiation, anthracycline

Clinical Manifestations of RCM

Symptoms of right and left heart failure can occur depending on the extent of involvement. JVP may show prominent x and y descents.

Endomyocardial fibrosis

Endomyocardial fibrosis is an important restrictive cardiomyopathy usually seen in the tropical and subtropical regions. EMF usually affects children and young adults. Large pericardial effusions are common in EMF. ECG may show diminished QRS voltage in these cases. Thrombus and fibrous tissue fill the ventricular apex, more commonly in the right ventricle. Inflow region is also involved while outflow region of the right ventricle is usually spared. This explains the right ventricular outflow tract pulsations seen in the third left intercostal space close to sternum. Atrial fibrillation is common in long standing cases. Mitral and tricuspid regurgitations are seen depending on the side which is involved. Huge dilatation of the right atrium is seen in right ventricular EMF. Pulmonary hypertension is seen in left ventricular EMF. There is no effective medical treatment for EMF and the management is largely supportive. Tricuspid valve replacement and endocardiectomy have been done in the past with limited results.

Carcinoid heart disease

Carcinoid syndrome manifests with cutaneous flushing, diarrhea and bronchospasm. Endocardial plaques seen in carcinoid heart disease are called ‘stuck on plaques’ because they appear as if ‘stuck on’ the endocardium of the valves with very little inflammation of adjacent tissue. Carcinoid tumours are seen mostly in the small bowel and appendix. Carcinoid tumors that invade the liver cause carcinoid heart disease with right heart involvement. Left heart involvement occurs only if there is metastasis to the lungs. This is because liver and lung inactivates the products of carcinoid tumours.

Treatment of RCM

No satisfactory medical therapy is available for restrictive cardiomyopathy. Drug therapy must be used with caution in RCM. Diuretics are use if the filling pressures are extremely high to lower it a bit. Undue diuresis can lead on to low output state and the ventricular filling is dependent on the elevated filling pressures. Vasodilators may decrease the filling pressure. Calcium channel blockers have been tried to improve diastolic compliance. Digitalis and other inotropes are usually not indicated in RCM. Digitalis may be useful in controlling the ventricular rate in atrial fibrillation with fast ventricular rate.