Hypertrophic obstructive cardiomyopathy

Question 1

Inheritance?

Answer 1

Autosomal dominant

Question 2

Who can it be fatal in?

Answer 2

Most common cause of sudden cardiac death in the young

Question 3

Pathophysiology?

Answer 3

• the most common defects involve a mutation in the gene encoding β-myosin heavy chain protein or myosin-binding protein C
• results in predominantly diastolic dysfunction
o left ventricle hypertrophy → decreased compliance → decreased cardiac output
• characterized by myofibrillar hypertrophy with chaotic and disorganized fashion myocytes (‘disarray’) and fibrosis on biopsy

Question 4

Associated with which conditions?

Answer 4

• Friedreich’s ataxia

- Wolff-Parkinson White

Question 5

Features?

Answer 5

• often asymptomatic
• exertional dyspnoea
• angina
• syncope
o typically following exercise
o due to subaortic hypertrophy of the ventricular septum, resulting in functional aortic stenosis
• sudden death (most commonly due to ventricular arrhythmias), arrhythmias, heart failure
• jerky pulse, large ‘a’ waves, double apex beat

Question 6

What murmur is heard?

Answer 6

Ejection systolic murmur
• increases with Valsalva manoeuvre and decreases on squatting
• hypertrophic cardiomyopathy may impair mitral valve closure, thus causing regurgitation

Question 7

What findings may be seen on echocardiography?

Answer 7

mnemonic - MR SAM ASH

• mitral regurgitation (MR)
• systolic anterior motion (SAM) of the anterior mitral valve leaflet
• asymmetric hypertrophy (ASH)

Question 8

What may be seen on ECG?

Answer 8

• left ventricular hypertrophy
• non-specific ST segment and T-wave abnormalities, progressive T wave inversion may be seen
• deep Q waves
• atrial fibrillation may occasionally be seen

Question 9

Management?

Answer 9

ABCDE
Amiodarone
Beta-blockers or verapamil for symptoms
Cardioverter defibrillator
Dual chamber pacemaker
Endocarditis prophylaxis*

Question 10

What drugs should be avoided?

Answer 10

• nitrates
• ACE-inhibitors
• inotropes