Overview
A ventricular septal defect (VSD) describes the presence of one or more holes in the ventricular septum which separates the left and right ventricles of the heart. The holes allow the shunting of blood between the ventricles.
The increased amount of blood in each ventricle puts more strain on them, which can lead to ventricular hypertrophy and heart failure. Like other causes of acyanotic congenital heart disease, if left untreated for too long, Eisenmenger syndrome can develop.
VSDs tend to be congenital, however, they can occur after myocardial infarction.
Epidemiology
- VSDs are the most common congenital heart defect in children
- Acquired VSDs (e.g. due to myocardial infarction) are much rarer
Associations
VSDs may be associated with:
- Chromosomal disorders:
- Down’s syndrome, 50% of cases are associated with congenital heart defects
- Edward’s syndrome
- Patau’s syndrome
- Other causes:
- Post-myocardial infarction
- Foetal alcohol syndrome
Presentation
The presence of symptoms depends on the severity of the VSD. Many infants may not have obvious symptoms and VSDs may be picked up on routine examinations. Features include:
- A pan-systolic murmur in the left parasternal region:
- Smaller VSDs tend to cause louder murmurs
- Failure to thrive
- Shortness of breath
- Eisenmenger syndrome
Investigations
Overview
Investigations include:
- ECG:
- Provides evidence of heart chamber hypertrophy
- Chest x-ray:
- May show cardiomegaly
- Echocardiography – diagnostic test of choice:
- Visualises VSD
Differential Diagnoses
Atrial septal defect
- The murmur heard tends to be ejection systolic and S2 has a wide and fixed (does not change with breathing) split.
Patent ductus arteriosus
- The murmur tends to be a continuous systolic and diastolic ‘machinery-like’ murmur
- A left subclavian thrill may be felt
Management
Overview
Management depends on the severity of the VSD and is coordinated by a specialist. It may involve:
- Monitoring – some small VSDs may close within 1-2 years
- Management of heart failure if it develops secondary to VSD
- Surgical closure of the defect
Complications
Eisenmenger syndrome
Left-to-right shunting increases the pressure in the right ventricle and pulmonary vasculature resulting in pulmonary hypertension. This puts more strain on the right ventricle, which results in right ventricular hypertrophy and increased right ventricular pressure.
Eventually, this exceeds the pressure of the left ventricle, and the shunt is reversed, resulting in deoxygenated blood flowing from the right to the left ventricle and entering the systemic circulation, bypassing the lungs. This leads to cyanosis and clubbing.
The development of Eisenmenger syndrome is an indication for a heart-lung transplant.
Aortic regurgitation
If the VSD is near the aortic valve, since blood is shunted between both ventricles, the pressure in each is different to normal physiological amounts. This can lead to instability of the aortic valve and prolapse, leading to aortic regurgitation.
Infective endocarditis
VSDs are associated with an increased risk of infective endocarditis due to turbulent flow across the VSD.
Prognosis
- Asymptomatic VSDs tend to close spontaneously in around 50% of infants
- Spontaneous closure of small VSDs is common in those <1 year old
- Early intervention and treatment before the development of complications is associated with a very good prognosis
- The prognosis is much worse in those with pulmonary hypertension or Eisenmenger syndrome
