Dilated cardiomyopathy

Question 1

How common is this?

Answer 1

Most common form of cardiomyopathy, accounting for 90% of cases.

Question 2

Causes?

Answer 2

• idiopathic: the most common cause
• myocarditis: e.g. Coxsackie B, HIV, diphtheria, Chagas disease
• ischaemic heart disease
• peripartum
• hypertension
• iatrogenic: e.g. doxorubicin
• substance abuse: e.g. alcohol, cocaine
• inherited: either a familial genetic predisposition to DCM or a specific syndrome e.g. Duchenne muscular dystrophy
o around a third of patients with DCM are thought to have a genetic predisposition
o a large number of heterogeneous defects have been identified
o the majority of defects are inherited in an autosomal dominant fashion although other patterns of inheritance are seen
• infiltrative e.g. haemochromatosis, sarcoidosis
• nutritional e.g. wet beriberi (thiamine deficiency)

Question 3

Pathophysiology?

Answer 3

• dilated heart leading to predominately systolic dysfunction
• all 4 chambers are dilated, but the left ventricle more so than right ventricle
• eccentric hypertrophy (sarcomeres added in series) is seen

Question 4

Symptoms and signs?

Answer 4

• classic findings of heart failure
• systolic murmur: stretching of the valves may result in mitral and tricuspid regurgitation
• S3

Question 5

What is seen on chest x-ray?

Answer 5

Balloon appearance