CARDIOMYOPATHY

In hypertrophic cardiomyopathy (HCM), there is decreased compliance due to the disorientation of myosin fibres. 40% of patients carry mutations of cardiac beta Myosin heavy chain on chromosome 14.

Maneouvres which decrease venous return will increase the intensity of the murmur

(valsalva – baroreceptor mediated fall in cardiac output, standing, nitrates).

Maneouvres which increase venous return will decrease the murmur as this overcomes the obstruction (squatting, long term beta blockers).

In summary, the murmur in HCM: increases in valsalva Maneouvre increases with standing

decreases with exercise decreases with squatting

Nitrates are best avoided because they are vasodilators which may cause hypotension with the condition. Beta blockers and calcium channel blockers help increase end diastolic filling and treat symptoms but have no effect on risk reduction of sudden death. Amiodarone improves survival.

Restrictive cardiomyopathy: Echocardiography showing no pericardial effusion and stiffness suggests restrictive rather than constrictive cardiomyopathy. The transmitral dopplers on the echo may show E/A wave reversal and high velocities which may suggest restrictive picture. This may be due to infiltration due to haemochromatosis, endomyocardial fibrosis, sarcoidosis, myeloma, lymphoma or connective tissue disease.