Hypertrophic cardiomyopathy

Hypertrophy of an undilated left ventricle for no apparent reason

Half of cases are inherited (autosomal dominant)

Hypertrophy of the right ventricle is also seen. There is diastolic dysfunction (as ventricular relaxation is impaired through the excess muscle). A double apical impulse is felt (plus pulsus bisferiens). As the muscle grows then outflow obstruction ensues - and mitral regurgitation can follow this. A jerky pulse is felt as the outflow obstruction is squirted past. Large JVP a waves are seen as the atria need to squeeze extra hard to get the blood into the hypertrophied right ventricle

A left sternal edge systolic thrill caused by ventricular turbulance can be felt. An ejection systolic murmer radiating to the axilla can be heard. This murmer increases with valsalva, standing and GTN and decreases with squatting (as the differential from the systemic resistance back into the hypertrophied left ventricle is not as great so the blood flow becomes less turbulant)

There are no diagnostic echocardiogram features, though aymmetrical septal hypertrophy is often seen. Banana or spade shaped cavity can be seen in systole, as can a sword fish shaped left anterior descending artery

Pregnancy: 25-50% mortality. Neonates born to diabetic mothers have a similar picture in about 1/3 but this usually resolves neonatally

Associations

• WPW
• Phaeochromocytoma
• Familial lentiginosis
• Friedrich's ataxia
• Sudden death