Ventricular Septal Defect (VSD)

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Patient Advice

Definition

Ventricular Septal Defect (VSD) is a congenital heart defect characterised by an abnormal opening in the ventricular septum, allowing blood to flow between the left and right ventricles. It is the most common congenital heart defect.

Aetiology

VSDs result from incomplete formation or fusion of the ventricular septum during fetal development. Causes include:

• Congenital: Associated with genetic syndromes like Down syndrome and Edward syndrome.
• Acquired: Rarely, due to myocardial infarction or trauma in adults.

Pathophysiology

The defect creates a left-to-right shunt, leading to the following changes:

• Increased Pulmonary Blood Flow: Blood from the high-pressure left ventricle flows into the right ventricle and pulmonary circulation.
• Volume Overload: Results in dilation of the left atrium and ventricle.
• Pulmonary Hypertension: Persistent overload can lead to irreversible pulmonary vascular changes.
• Eisenmenger Syndrome: Reversal of the shunt to right-to-left due to severe pulmonary hypertension.

Risk Factors

Risk factors for VSD include:

• Family history of congenital heart defects.
• Maternal infections during pregnancy (e.g., rubella).
• Chromosomal abnormalities (e.g., Down syndrome).
• Exposure to teratogens such as alcohol or certain medications during pregnancy.

Signs and Symptoms

Clinical features vary based on the size of the defect:

• Small VSD: Often asymptomatic and detected incidentally by a murmur.
• Moderate to Large VSD:
  • Heart Murmur: Harsh holosystolic murmur heard best at the left lower sternal border.
  • Failure to Thrive: Poor feeding and weight gain in infants.
  • Tachypnoea: Increased respiratory rate due to pulmonary congestion.
  • Recurrent Respiratory Infections: Due to pulmonary overcirculation.
  • Cyanosis: In late stages with Eisenmenger syndrome.

Investigations

Diagnostic tests and expected findings include:

• Clinical Examination: Detection of a loud murmur or signs of heart failure.
• Chest X-ray: Shows cardiomegaly and increased pulmonary vascular markings.
• Echocardiography: Diagnostic test of choice:
  • Demonstrates the defect and blood flow across the septum.
  • Assesses the size and impact of the VSD on cardiac function.
• Electrocardiogram (ECG): May show left or biventricular hypertrophy.
• Cardiac Catheterisation: Reserved for complex cases to measure pulmonary pressures and assess operability.

Management

1. Medical Management

• Diuretics: E.g., furosemide to relieve symptoms of pulmonary congestion.
• ACE Inhibitors: E.g., enalapril to reduce afterload and improve symptoms.
• Caloric Support: Optimisation of nutrition in infants with failure to thrive.

2. Surgical and Interventional Management

• Small VSDs: Often close spontaneously and require monitoring.
• Moderate to Large VSDs:
  • Device Closure: Minimally invasive transcatheter closure using a closure device.
  • Surgical Repair: Open-heart surgery to close the defect with a patch, indicated for symptomatic or hemodynamically significant VSDs.

3. Specialist Referral

Referral to a paediatric cardiologist is essential for assessment, management planning, and long-term follow-up.

Patient Advice

Key advice includes:

• Attend regular follow-up appointments with a cardiologist.
• Monitor growth and developmental milestones in infants.
• Ensure good oral hygiene to reduce the risk of infective endocarditis.
• Report symptoms such as increased breathlessness, poor feeding, or recurrent infections immediately.
• Parents should be educated about the condition and the importance of follow-up.