HYPERTROPHIC CARDIOMYOPATHY

Marked LV hypertrophy; often asymmetric, without underlying hypertension or valvular disease. Systolic function is usually normal; increased LV stiffness results in elevated diastolic filling pressures. Typically results from mutations in sarcomeric proteins (autosomal dominant transmission).



Symptoms 

Secondary to elevated diastolic pressure, dynamic LV outflow obstruction (if present), and arrhythmias; dyspnea on exertion, angina, and presyncope; sudden death may occur.

Physical Examination 

Brisk carotid upstroke with pulsus bisferiens; S4, harsh systolic murmur along left sternal border, blowing murmur of mitral regurgitation at apex; murmur changes with Valsalva and other maneuvers .


Laboratory ECG 

LV hypertrophy with prominent “septal” Q waves in leads I, aVL, V5–6. Periods of atrial fibrillation or ventricular tachycardia are often detected by Holter monitor.
Echocardiogram LV hypertrophy, often with asymmetric involvement, especially of the septum or apex; LV contractile function typically excellent with small endsystolic volume. If LV outflow tract obstruction is present, systolic anterior motion (SAM) of mitral valve and midsystolic partial closure of aortic valve are present. Doppler shows early systolic accelerated blood flow through LV outflow tract.

Hypertrophic Cardiomyopathy TREATMENT

Strenuous exercise should be avoided. Beta blockers, verapamil, or disopyramide used individually to reduce symptoms. Digoxin, other inotropes, diuretics, and vasodilators are generally contraindicated. Endocarditis antibiotic prophylaxis (Chap. 89) is necessary only in pts with a prior history of endocarditis. Antiarrhythmic agents, especially amiodarone, may suppress atrial and ventricular arrhythmias. However, consider implantable cardioverter defibrillator for pts with high-risk profile, e.g., history of syncope or aborted cardiac arrest, nonsustained ventricular tachycardia, marked LVH (>3 cm), exertional hypotension, or family history of sudden death. In selected pts, LV outflow gradient can be reduced by controlled septal infarction by ethanol injection into the septal artery. Surgical myectomy may be useful in pts refractory to medical therapy.