Restrictive cardiomyopathies (RCM)
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.Noninfiltrative: Idiopathic, scleroderma
3.Storage Disease: Hemochromatosis, Fabry’s disease and glycogen storage disorders
Endomyocardial diseases
1.Endomyocardial fibrosis (EMF)
2.Hyperesinophilic 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 extend 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 effusion are common in EMF. ECG may show diminished QRS voltage in these cases. Thormbus and fibrous tissue fill the ventriclur 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 regurgitation 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.
Right ventricular endomyocardial fibrosis – echocardiogram (video) and X-ray chest
Endomyocardial fibrosis is type of restrictive cardiomyopathy seen mostly in the tropics and sub tropics. There is progressive fibrosis and obliteration of the right ventricle, predominantly the inflow tract and the apex. The right ventricular outflow tract (RVOT) is relatively spared and is often dilated. This leads to the physical finding of RV outflow pulsations, a wavy pulsation in the third left intercostal space close to the sternum. The restriction of inflow into the right ventricle elevates the venous pressure greatly. The right atrium is grossly dilated. Features of systemic venous congestion predominate in advanced cases with hepatomegaly, ascites and generalised edema.
Echocardiogram in right ventricular endomyocardial fibrosis
Echocardiogram in apical four chamber view demonstrating salient features of right ventricular endomyocardial fibrosis. The right atrium is grossly dilated and the interatrial septum is pushed to the left. The left ventricle and left atrium are normal, though the left atrium appears compressed by the huge right atrium. Right ventricular cavity is very small, seen just distal to the tricuspid valve, beyond the right atrium. Dense fibrosis with calcification of right venticular cavity and apex is the hall mark of endomyocardial fibrosis. A corresponding dimple will be seen near the apex on the surface. Clinically the grossly enlarged right atrium can be percussed out to the right of the sternal border.
Echocardiogram in right ventricular endomyocardial fibrosis with tricuspid regurgitation
Colour Doppler evaluation demonstrates significant tricuspid regurgitation (TR). Doppler interrogation will reveal that it is a low velocity TR, unlike in pulmonary hypertension, where the TR velocity is high. A high velocity TR jet can be seen in left ventricular endomyocardial fibrosis (LVEMF) with pulmonary hypertension or if there is associated mitral stenosis (see below). Even though the TR in this case is low velocity, it shows aliasing and variance with multiple colours (mosaic) because the Nyquist limit of the colour Doppler is set at 60 cm / sec (see the colour bar at the top right corner) which corresponds to a gradient of only 1.44 mm Hg. That means aliasing will occur if the gradient is just above 1.44 mm Hg.
Video from the apical four chamber view showing both two dimensional echocardiography and colour flow mapping (CFM, colour Doppler). The abnormal motion of the interventricular septum tethered by the right ventricular fibrosis is interesting. The view is almost an apical five chamber view when the TR jet is visible. The mosaic (multi-coloured) jet is seen flowing into the right atrium from the right ventricle in systole. The antegrade flow into the tricuspid valve from the right atrium is encoded in red colour as it is towards the transducer kept at the apex.
Right atrial thrombus in right ventricular endomyocardial fibrosis
The grossly dilated right atrium causes stasis of blood in the right atrium. This often causes thrombus formation in the right atrium as illustrated above. The thrombus can be either mobile or adherent to the atrial wall. A mobile thrombus can embolise producing pulmonary embolism and its sequelae, sometime presenting as pulmonary hypertension. Right ventricular apical fibrosis is evident in the right panel. In this case, the involvement of right ventricular cavity is lesser than in the previous case which has a documented history of over 20 years.
X-ray chest PA view in right ventricular endomyocardial fibrosis with pericardial effusion
X-ray chest in an advanced case of right ventricular endomyocardial fibrosis often shows gross enlargement of the cardiac silhouette, predominantly contributed by the right atrial enlargement. But it can also be partly due to associated pericardial effusion as in this case. Varying degrees of pericardial effusion is a common association of severe right ventricular endomyocadial fibrosis with systemic venous congestion and anasarca.
X-ray chest PA view in right ventricular endomyocardial fibrosis and rheumatic mitral stenosis
Features of pulmonary arterial hypertension in endomyocardial fibrosis (EMF) could be either due to left ventricular involvement and consequent elevation of left atrial and pulmonary venous pressures or due to pulmonary embolism from a right atrial thrombus as demonstrated earlier. But the x-ray shown above shows pulmonary venous hypertension (prominent upper lobe veins), bulging of the left atrial appendage and prominence of main pulmonary artery. Though this could be due to associated left ventricular EMF, but in this case there was a history of previous closed mitral valvotomy for rheumatic mitral stenosis, now presenting with restenosis. The presence of associated right ventricular endomyocardial fibrosis was documented by echocardiography. Another possibility for explaining the right atrial enlargement in this case is mitral stenosis with tricuspid valve disease, both of rheumatic etiology.
X-ray chest PA view in left ventricular endomyocardial fibrosis
Finally and X-ray chest PA view in left ventricular EMF, mimicking and X-ray in mitral stenosis, with prominent left atrial appendage, double atrial contour (shadow in shadow), right atrial enlargement, pulmonary venous congestion and main pulmonary artery prominence. Echocardiography showed that there was LVEMF and no mitral stenosis. Pulmonary arterial hypertension was also present.
Treatment of EMF is restricted to symptomatic measures to relieve pulmonary and venous congestion as the case may be. Severe ascites may require periodic paracentesis to relieve tension and give symptomatic relief. Endocardiectomy and mitral / tricuspid valve replacements were being done earlier. Prosthetic valve thrombois is an important complication of tricuspid valve replacement. They present with worsening of systemic venous congestion and ascites.
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 procucts 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 prssures are extremely high to lower it a bit. Undue diuresis can lead on to low output state and the ventricular filling is dependant 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.
Combination of constrictive pericarditis with restrictive cardiomyopathy
Combination of constrictive pericarditis with restrictive cardiomyopathy can occur after radiation as well as with cardiac transplant rejection. In case of transplant it is the pericardiotomy which can cause constriction while the rejection process can lead to restrictive cardiomyopathy. Radiation is the cause for both constrictive pericarditis and restrictive cardiomyopathy in post radiation cases.