Hypertrophic (Obstructive) Cardiomyopathy

Question 1

What are the causes of Hypertrophic Obstructive Cardiomyopathy? (2)

Answer 1

1. Autosomal dominant mutation
2. Friedreich’s Ataxia - trinucleotide repeat

Question 2

What proteins does HOCM affect?

Answer 2

Beta Heavy chains of myocin

Reduces sarcomere function, reduces cardiac function, causes growth hormones, increases myoctye growth

Question 3

What type of hypertrophy occurs in HOCM?

Answer 3

Concentric,
Asymmetrical

Question 4

What are the clinical features (on examination) of HOCM? (2)

Answer 4

1. Crescendo-decrescendo ejection systolic murmur (MR)
   This reduces in intensity when squatting or straight leg raising
2. S4

Question 5

What are the history features of HOCM?

Answer 5

Reduced cardiac output causes:

1. Reduced brain perfusion -> syncope
2. Reduced cardiac muscle perfusion ->

• Angina
• Dyspnoea
• Arrhythmias - > sudden cardiac death

Question 6

How is HOCM managed? (6)

Answer 6

1. Low fluids and diuretics
2. Beta blockers
3. Diltazem and verapamil (certain CCBs)
4. ICD
5. Myectomy - thin the walls
6. Alcohol ablation - to cause some of the tissue to die and thin the walls

Question 7

What does the OBSTRUCTION part of the name refer to?

Answer 7

As blood leaves the left ventricle rapidly (due to increased contraction strenght of thickened walls) it pulls the mitral valve with it. This can ‘stick’ to the bulging septal wall

Venturi effect