Ventricular Septal Defect
On this page
Direct answer
Ventricular septal defect (VSD) is an opening in the interventricular septum that allows left-to-right shunting, and it is the commonest congenital heart defect. The perimembranous type is the most frequent, producing a pansystolic murmur best heard at the lower left sternal border. Small defects often close spontaneously, whereas large defects with high pulmonary flow can cause heart failure and, eventually, Eisenmenger syndrome.
What you must remember
- Commonest defect: VSD accounts for the largest share of congenital heart disease, both alone and within complex lesions.
- Perimembranous: the most common type, near the membranous septum, and the one that can close with tissue from the septal tricuspid leaflet.
- Muscular: may be multiple, giving a Swiss-cheese septum, and many small muscular defects close spontaneously.
- Subarterial (supracristal): lies below the pulmonary or aortic valve, with a risk of aortic regurgitation from prolapse of the right coronary cusp.
- Murmur: a pansystolic murmur with a thrill at the lower left sternal border; a small defect gives a loud murmur, and a large defect with raised pulmonary resistance gives a soft one.
- Heart failure: large defects usually declare themselves around 6 to 8 weeks of age, as pulmonary resistance falls, with sweating during feeds and poor weight gain.
- Eisenmenger syndrome: irreversible pulmonary vascular disease that reverses the shunt and causes cyanosis, making closure contraindicated.
From murmur to closure decision
A VSD is assessed by its size, the pulmonary pressure it generates and the symptoms it causes. The closure decision depends on how much the shunt loads the heart.
- Clinical assessment: Look for a pansystolic murmur, a thrill and signs of heart failure such as poor weight gain and recurrent chest infections.
- Chest X-ray and ECG: A significant shunt shows left atrial and left ventricular enlargement and increased pulmonary vascularity.
- Echocardiography: Echo locates the defect, identifies its type, estimates pressures and shunt size, and checks the aortic valve in subarterial defects.
- Medical support: Heart failure is treated with diuretics, afterload reduction and calorie-dense feeds while the infant grows.
- Closure decision: Surgical or device closure is considered for significant defects with heart failure, poor growth or raised pulmonary pressure, while small defects are watched.
- Follow-up: Long-term review looks for endocarditis, aortic regurgitation and pulmonary hypertension.
Where the exam tries to catch you
Most VSD questions test the murmur and the natural history, not the surgery.
- Trap: a louder murmur means a bigger defect. Correct: a small defect creates high-velocity flow and a loud murmur, while a large defect with raised pulmonary resistance may produce a soft murmur.
- Trap: Eisenmenger syndrome is an early complication of VSD. Correct: it develops late, after years of unrepaired shunting has raised pulmonary vascular resistance, and reversal makes repair contraindicated.
- Trap: a subarterial VSD is managed like a perimembranous one. Correct: subarterial defects risk aortic regurgitation from cusp prolapse, so the aortic valve must be checked on echo.
Frequently asked questions
Which is the most common type of ventricular septal defect?
The perimembranous type is the most common ventricular septal defect, located near the membranous part of the septum. It can close spontaneously when tricuspid valve tissue grows across it. Muscular defects are also common but are often multiple and small.
Does every ventricular septal defect need surgery?
No. Small ventricular septal defects often close spontaneously and need only follow-up. Surgical or device closure is reserved for large defects causing heart failure, poor growth or raised pulmonary pressure.
What murmur is typical of a ventricular septal defect?
A pansystolic murmur with a thrill at the lower left sternal border is typical of a ventricular septal defect. Loudness does not indicate defect size, and the murmur can soften as pulmonary pressure rises.
Why does a subarterial ventricular septal defect need aortic valve review?
A subarterial ventricular septal defect can lead to prolapse of the right coronary aortic cusp, causing aortic regurgitation. Echocardiography should therefore check the aortic valve during follow-up.
When does heart failure appear in a large ventricular septal defect?
Heart failure in a large ventricular septal defect usually appears around 6 to 8 weeks of age, when pulmonary vascular resistance falls. Symptoms include sweating during feeds, poor weight gain and tachypnoea.