Hypertrophic obstructive cardiomyopathy

Question 1

Hypertrophic obstructive cardiomyopathy (HOCM)

Answer 1

An autosomal dominant disorder of muscle tissue caused by defects in the genes encoding contractile proteins. HOCM is important as it is the most common cause of sudden cardiac death in the young.

Question 2

Hypertrophic obstructive cardiomyopathy (HOCM) mode of inheritance

Answer 2

autosomal dominant

Question 3

HOCM 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
> 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

What are the characteristics of HOCM?

Answer 4

Predominantly diastolic dysfunction
> left ventricle hypertrophy → decreased compliance → decreased cardiac output
> characterized by myofibrillar hypertrophy with chaotic and disorganized fashion myocytes (‘disarray’) and fibrosis on biopsy

Question 5

Features of HOCM

Answer 5

>

often asymptomatic
exertional dyspnoea
angina
syncope typically following exercise
sudden death (most commonly due to ventricular arrhythmias), arrhythmias, heart failure
jerky pulse, large 'a' waves, double apex beat
ejection systolic murmur

Question 6

What murmur is present in HOCM?

Answer 6

ejection systolic murmur

Question 7

What are the conditions associated with HOCM?

Answer 7

1) Friedreich’s ataxia

2) Wolff-Parkinson White

Question 8

ECG changes in HOCM

Answer 8

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