Cardiac failure

Question 1

HF - pathophysiology

Answer 1

Underlying pathology leading to compromise of cardiac stroke volume -> cardiac decompensation -> heart failure:
1. Increased afterload (pressure work)
2. Increased preload (volume work)
3. Myocardial abnormalities
4. Tachyarrhythmias
___
5. May lead to symptoms of poor tissue perfusion
alone (e.g. fatigue, poor exercise tolerance, confusion) and/or by symptoms
of congestion of circulation (e.g. dyspnoea, pleural effusion, pulmonary
oedema, hepatomegaly, peripheral oedema)

Question 2

HF - causes

Answer 2

In children, the most common cause = congenital structural defects of the heart

1. Large left to right shunt: e.g. large VSD (not in first few days of life).
2. Left-sided obstructive lesions: coarctation of aorta; hypoplastic left side of heart (within first few days of life).
3. Cardiomyopathy: hypertrophic; dilated; restrictive. Myocarditis: viral; rheumatic fever. Endocarditis.
4. Tachyarrhythmias: supraventricular tachycardia.
5. Other (2):
   - Myocardial ischaemia: anomalous left coronary artery; Kawasaki disease
   - High-output: severe anaemia; thyrotoxicosis; AV malformations

Question 3

HF - clinical features

Answer 3

Depend on the degree of cardiac reserve. Most common symptoms and signs:

1. Dyspnoea, tachypnoea, coughing, lung crepitations
2. Poor feeding (infant), poor weight gain and failure to thrive
3. Hepatomegaly, cardiomegaly
4. Tachycardia/’gallop’ heart rhythm
5. Sweating

Note: There are usually few signs of systemic congestion as observed in adults. (What about hepatomegaly?) Only children with chronic heart failure, or adolescents, may have ‘adult’ signs such as oedema, orthopnoea, paroxysmal nocturnal dyspnoea, ankle oedema and elevated JVP.

Question 4

HF - ix

Answer 4

Directed at finding a cause and quantifying function.

1. Chest radiograph:
   - Cardiac enlargement;
   - Lungs—oligaemic (?) /oedema.
2. Echocardiography: congenital heart defects.
3. Arterial blood gas: reduced PO2/metabolic acidosis.
4. ECG: not diagnostic, but may assist in establishing aetiology.
5. Serum electrolytes: hyponatraemia due to water retention.

Question 5

HF - mx

Answer 5

*Underlying cause of HF must be treated.

General measures:

1. Bed rest and nurse in semi-upright position: infants in chair/seat.
2. Supplemental oxygen (not in left to right shunt).
3. Diet: sufficient calorie intake.
4. Diuretics.
5. Angiotensin converting enzyme inhibitors.