HOCM Flashcards
What is hypertrophic obstructive cardiomyopathy (HOCM)?
An autosomal dominant disorder of muscle tissue caused by defects in the genes encoding contractile proteins.
What is the estimated prevalence of HOCM?
1 in 500.
What is the significance of HOCM?
It is the most common cause of sudden cardiac death in the young.
What are the most common genetic defects in HOCM?
Mutation in the gene encoding β-myosin heavy chain protein or myosin-binding protein C.
What type of dysfunction is predominantly seen in HOCM?
Diastolic dysfunction.
What are the pathophysiological changes in HOCM?
Left ventricle hypertrophy → decreased compliance → decreased cardiac output.
What histological features characterize HOCM?
Myofibrillar hypertrophy with chaotic and disorganized fashion myocytes (‘disarray’) and fibrosis on biopsy.
What are common symptoms of HOCM?
Often asymptomatic, exertional dyspnoea, angina, syncope.
What triggers syncope in HOCM patients?
Typically following exercise due to subaortic hypertrophy of the ventricular septum, resulting in functional aortic stenosis.
What is a major cause of sudden death in HOCM?
Ventricular arrhythmias.
What are some clinical signs of HOCM?
Jerky pulse, large ‘a’ waves, double apex beat.
What type of murmurs are associated with HOCM?
Systolic murmurs, ejection systolic murmur, pansystolic murmur.
What causes the ejection systolic murmur in HOCM?
Left ventricular outflow tract obstruction.
How does the ejection systolic murmur change with Valsalva manoeuvre and squatting?
Increases with Valsalva manoeuvre and decreases on squatting.
What causes the pansystolic murmur in HOCM?
Systolic anterior motion of the mitral valve → mitral regurgitation.
What are two conditions associated with HOCM?
- Friedreich’s ataxia
- Wolff-Parkinson White.
What mnemonic is used for echo findings in HOCM?
MR SAM ASH.
What does the ‘MR’ in the echo findings mnemonic stand for?
Mitral regurgitation.
What does ‘SAM’ in the echo findings mnemonic refer to?
Systolic anterior motion of the anterior mitral valve leaflet.
What does ‘ASH’ in the echo findings mnemonic refer to?
Asymmetric hypertrophy.
What are common ECG findings in HOCM?
Left ventricular hypertrophy, non-specific ST segment and T-wave abnormalities, deep Q waves.
What abnormal rhythm may occasionally be seen on ECG in HOCM?
Atrial fibrillation.
