Cardio - Cardiomyopathies

Question 1

name the 3 main types of cardiomyopathy

Answer 1

1. dilated CM (most common)
2. hypertrophic CM
3. restrictive CM

Question 2

what is the aetiology for dilated CM?

Answer 2

Often unclear, causes can include:

• idiopathic
• drugs and toxins, inc. cocaine, alcohol and some chemos
• genetic (usually autosomal dominant)
• post-partum
• autoimmune, e.g. RA, SLE
• infiltrative, e.g. haemochromatosis, amyloidosis, sarcoidosis
• infective, e.g. chronic Chagas’, HIV, Lyme disease, etc.

Question 3

how does a pt with dilated CM usually present?

Answer 3

Sx of congestive HF: dyspnoea, PND, orthopnoea, oedema, fatigue, raised JVP, S3

Question 4

explain the pathophysiology of dilated CM

Answer 4

Ventricular chamber dilation and contractile dysfunction:

i) decreased SV… systolic CHF
ii) mitral and/or tricuspid valve rergurgitation
iii) arrhythmias (e.g. AF) due to irritated cells of conduction system

Question 5

how would you diagnose dilated CM?

Answer 5

1. ECG abnormalities
2. TEE: LV dilation, end-diastolic dimension >112% of predicted, is normal/decreased wall thickness, EF <45%
3. CXR: cardiomegaly

Question 6

what is the aetiology for hypertrophic cardiomyopathy

Answer 6

Genetic mutation causing disorganised cardiac myocytes and unexplained LVH.

• 50% familial (autosomal dominant)
• 50% spontaneous

Question 7

explain the pathophysiology of hypertrophic CM

Answer 7

Asymmetric hypertrophy of superior septum (+/- other areas of ventricule wall):

i) dynamic outflow obstruction (HOCM)… decreased CO
ii) ischaemia (due to decreased CO and hypertrophy increasing O2 demands)… MI and/or tachyarrythmias
iii) can have mitral regurgitation

Question 8

what is the usual presentation of hypertrophic CM?

Answer 8

Very variable:

• many remain asymptomatic
• some develop severe diastolic HF
• AF (20% of cases)
• sudden cardiac death (most common cause in young)

Question 9

which signs O/E can indicate HCM?

Answer 9

• systolic crescendo-decrescendo murmur
• forceful apex beat with double impulse (if LV outflow tract obstructed)
• +/- signs of mitral regurgitation

Question 10

how would you diagnose hypertrophic CM?

Answer 10

1. ECG abnormalities, e.g. AF, ST segment changes, T wave inversion
2. TEE: asymmetric septal hypertrophy (>15 mm) with a ratio of septal wall to posterior wall thickness >1.4:1, preserved systolic function

Question 11

what is the aetiology for restrictive CM?

Answer 11

Most common forms:

• idiopathic
• endomyocardial fibrosis (Loffler’s syndrome)
• infiltrative: amyloidosis (most common cause in western world), haemochromatosis, glycogen
• sarcoidosis

Question 12

explain the pathophysiology of restrictive CM

Answer 12

Myocardial stiffness… incompliant ventricle and decreased diastolic filling:

i) diastolic HF
ii) increased LA pressure… atrial dilation… AF

Question 13

describe the usual presentation of restrictive CM

Answer 13

• Symptoms of HF, with features of RHF predominating: dyspnoea, fatigue, oedema, ascites, hepatomegaly, rapised JVP
• AF

Question 14

how would you diagnose restrictive CM?

Answer 14

1. ECG abnormalities
2. Echo: non-dilated ventricles with impaired ventricular filling, normal EF
3. cardiac MRI: useful for distinguishing from constrictive pericarditis, can see deposits of fat, iron or amyloid, etc.
4. RV biopsy (gold standard): to ID deposits

Question 15

how would you manage a pt with CM?

Answer 15

Pharmacological Mx:

i) loop diuretics, e.g. furosemide to reduce pulmonary and peripheral oedema
ii) B-blockers or CCBs to treat any arrythmias
iii) B-blockers and ACEi to treat HF

Surgical Mx:

i) implantable cardioverted defibrillator (ICD) or cardiac resynchronisation therapy (CRT) pacemaker if LV EF <35% or recurrent VT or malignant arrythmias
ii) surgical myectomy or alcohol septal ablation may be considered for relief of outflow obstruction
iii) left-ventricular assist device (LVAD)
iv) heart transplant