Ventricular septal defect

Question 1

Definition & pathophysiology & complication

Answer 1

• Congenital hole in the interventricular septum allows shunting of blood from left ventricle → right ventricle. This is an acyanotic (not blue) shunt as oxygenated blood is pumped to the lungs, rather than deoxygenated blood passing from the RHS→ LHS & bypassing the lungs. Like an ASD, if untreated it can lead to Eisenmenger’s syndrome: pulmonary arterial hypertension causes RHS pressures to increase→ shunt reverses & becomes right to left resulting oxygenated blood bypassing the lungs & being pumped to the systemic circulation causing cyanosis.
• More severe than atrial septal defect

Question 2

Presentation of Eisenmenger’s syndrome?

Answer 2

Clubbing, central & peripheral cyanosis, dyspnoea, low O2 saturation (hypoxaemia), plethoric complexion (due to compensatory polycythaemia- bone marrow makes more RBCs due to hypoxaemia to increase O2 carrying capacity of blood)

Question 3

Clinical manifestation

Answer 3

Small VSD = asymptomatic. Large VSD is more severe, presents earlier & is more severe than ASD.

Typical presentation = small breathless, tachypnoaeic skinny baby with failure to thrive & tachycardia
For large VSD in infants:
SIGNS:
- Pansystolic murmur at the left lower sternal border
- Tachypnoea (raised respiratory rate)
- Tachycardia
- Cyanosis (if Eisenmenger’s syndrome has occurred)

SYMPTOMS:
- Dyspnoea
- Poor feeding
- Failure to thrive (poor weight gain, dropping off height & weight centiles)

Question 4

Differential diagnosis for pansystolic murmur

Answer 4

• mitral regurgitation (during systole, blood flows back from LV→ LA throughout systole)
• ventricular septal defect (throughout systole, blood flows from LV→RV as let-sided pressures are higher)

Question 5

Investigations

Answer 5

Echocardiogram = diagnostic

Question 6

Management

Answer 6

1st line = Watch and wait: for small VSD as they can close spontaneously

2nd line = Surgical closure of VSD

• Transvenous-catheter closure (via femoral vein)
• Open heart surgery

2nd line = Antibiotic prophylaxis: should be considered due to increased risk of infective endocarditis during surgery (non-specific symptoms; fever & new regurgitant murmur→ think infective endocarditis as a DDx)

Question 7

Complications

Answer 7

• Eisenmenger’s syndrome (cyanotic shunt)
  
  • Increased pulmonary blood flow leads to pulmonary arterial hypertension & right ventricular hypertrophy (to compensate for increased afterload)→ right sided pulmonary pressure > systemic pressures leading to reversal of shunt.
  • Blood is now shunted from right → left across the ventricular septa defect resulting in deoxygenated blood bypassing the lungs & being pumped to the systemic ciruclation. This results in cyanosis.
• Cor pulmonale (right heart failure due to pumonary arterial hypertension)