CARDIOMYOPATHY …These are diseases where cardiac enlargement occurs without any known cause. There is absence of ischaemic, hypertensive, rheumatic, syphilitic and congenital heart diseases.
Classification is now based upon features of presentation and pathophysiology.
- Dilated cardiomyopathy
Common causes are idiopathic, alcoholic, myocarditis, postpartum, doxorubicin, endocrinopathies, genetic disorders, amyloidosis, sarcoidosis, haemochromatosis, diabetes mellitus.
- Hypertrophic cardiomyophathy
Common causes are hereditary syndrome and chronic hypertension.
- Restrictive cardiomyopathy
Common causes are amyloidosis, radiation, open heart surgery diabetes mellitus, endomyocardial fibrosis, sarcoidosis, haemochromatosis, connective tissue diseases.
Clinically cardiomyopathy may present any of the following three features.
Congestive cardiomyopathy (dilated cardiomyopathy)
This is the commonest type. Here patients have oedema, breathlessness, engorged neck veins, increased heart rate, ectopics or atrial fibrillation. Evidences of biventricular enlargement are present. Triple rhythm is often present on auscultation over mitral and tricuspid areas. Murmurs of mitral and tricuspid incompetence are present. ECG shows evidences of ventricular enlargement, ST-T changes, conduction biventricular enlargement with pulmonary congestion. disturbances and arrhythmias. X-ray of chest shows.Echocardiography is helpful to differentiate it from pericardial effusion, aortic stenosis or mitral valve disease. LV volume and ejection fractions are also noted. If the diastolic volume is markedly increased and ejection fraction is less than 20 % they carry poor prognosis. Cardiac catheterization is not required but may be done to rule out CAD.
Constrictive cardiomyopathy (Restrictive Cardiomyopathy)
This is rare and simulates constrictive pericarditis as the .thickened myocardium resists ventricular filling.
Clinically neck veins are engorged, with prominent X and Y descents, liver is enlarged with pulsation, moderate ascites and sometimes pulsus paradoxus is present. All these features simulate constrictive pericarditis. Heart sounds are normal and there is no ventricular enlargement. Skiagram of chest shows normal size of the heart or there may be slight enlargement. ECG shows some ST-T changes. LV hypertrophy is uncommon but conduction defect and arrhythmia may occur. Chest X-ray shows concentric LV hypertrophy with dialatation but not very prominent.
Intracardiac calcification may be present. Two dimensional Echo Doppler and angiography will show two types of diastolic abnormality viz. abnormality of relaxation and restrictive filling. Other diastolic abnormality like early diastolic filling may result in increased E wave. Systolic function is relatively preserved. Prominent X and rapid Y descent will produce M shaped patterns.
Obstructive cardiomyopathy (Hypertrophic obstructive cardiomyopathy)
This is rare. Here the ventricular septum is massively hypertrophied resulting in narrowing of the inflow and outflow tracts of both ventricles. Clinically breathlessness, angina and syncope are present. Jerky pulse, prominent ‘a’ wave in jugular vein, biventricular hypertrophy, basal systolic thrill and late systolic murmur, mitral and tricuspid valvular incompetence due to papillary muscle dysfunctio may be present; there may be double impulses at the apex, sometimes triple cardiac impulse called triple ripple (which is diagnostic of this condition) and triple rhythm on auscultation are also present. Amyl nitrite/Isoproterenol will aggravate the obstruction and hence prominent systolic obstruction murmur will be heard. Phenylephrine because of its opposite effect will minimize the murmur. The murmur is also prominent after Valsalva manoeuvre. The pulse pressure will be low following an Ectopic beat (Brocken Brough’s sign). Skiagram of chest shows left and right ventricular enlargement. ECG shows ventricular enlargement andconduction defect. Doppler echo is very much helpful and will show normal aortic valve, asymmetric hypertrophy of the IV septum and systolic anterior motion of the anterior cusp of the mitral valve. Cardiac catheterization is only required to rule out CAD.
Salt-poor diet, Diuretics are tried but not very much effective. Digitalis does not act well, sometimes Beta adrenergic blocking drugs in small.doses may work well. In severe cardiac failure vasodilator like ACE inhibitors may be helpful. Dynamic cardiomyoplasty operation is done in some centres. Cardiac transplantation is the treatment of choice when there is class III or IV cardiac failure.
Medical treatment consists of Beta blockers like propranolol. Sometimes Calcium channel blockers like Nifedepine and Verapamil may also be helpful by improving the diastolic filling. For ventricular arrhythmia Disopyramide or Amiodarone are useful. Surgical treatment consists of resection of hypertrophic muscle in the ventricular outflow tract, mitral valve replacement or even creating Bundle branch block. Dual chamber pacing prevents progression of hypertrophy. Implantable defibrillators are useful for patients with unexplained and family history of sudden death.
There is no specific treatment and treatment should be directed for the underlying cause, if present.