AKT · Child health/Congenital heart

Ventricular septal defect (VSD)

Acyanotic left-to-right shunt through a defect in the interventricular septum (commonest CHD)

Overview

The commonest congenital heart defect — a hole in the interventricular septum giving a left-to-right shunt. Small VSDs are often asymptomatic with a loud murmur and close spontaneously; large VSDs cause heart failure in infancy and, if untreated, pulmonary hypertension and eventually Eisenmenger (shunt reversal). Associated with Down syndrome. A PANSYSTOLIC murmur at the lower left sternal edge.

Recognise

PANSYSTOLIC murmur at the LOWER LEFT sternal edge (louder with a SMALLER defect); systolic thrill
Large VSD: heart failure in infancy — breathlessness/sweating on feeding, faltering growth, recurrent chest infections, tachypnoea, hepatomegaly
Associations: Down syndrome, fetal alcohol syndrome; risk of infective endocarditis

Red flags

Heart failure in infancy (large VSD) → diuretics + surgical closure
Development of pulmonary hypertension → EISENMENGER (shunt reverses → cyanosis) — irreversible, the window for closure is missed

Differentials & how to tell them apart

Innocent murmursoft, systolic, asymptomatic, no thrill/diastolic component, normal echo

Atrial septal defectejection systolic murmur + FIXED split S2 (not pansystolic)

Mitral regurgitationpansystolic at the apex radiating to axilla

Investigations

Echocardiography (diagnostic — size, location, shunt); ECG/CXR (cardiomegaly, pulmonary plethora in large shunts).

Management

Small → observe (often closes); large/symptomatic → diuretics then surgical closure

1Small asymptomatic VSD: monitor (many close spontaneously). Large VSD with heart failure: diuretics ± ACE inhibitor, high-calorie feeds, then surgical closure.Gate: Close a large VSD BEFORE irreversible pulmonary hypertension/EISENMENGER develops — once the shunt reverses (cyanosis), closure is contraindicated; counsel endocarditis awareness
2Surgical or transcatheter device closure; manage heart failure; endocarditis prophylaxis in specific situations.

Diuretics (± ACE inhibitor) for heart failure — medical management of a large symptomatic VSD before surgery; high-calorie feeds

Surgical/device closure — for large/symptomatic defects or failure to thrive — close before pulmonary hypertension develops

Key points

Loud PANSYSTOLIC murmur at the lower left sternal edge (louder = smaller defect) = VSD, the commonest CHD. Large defects cause infant heart failure → close before Eisenmenger. Think Down syndrome.

Monitor & prognosis

Growth, heart failure, echo (spontaneous closure); pulmonary pressures.

Small VSDs excellent (close); large need timely surgery.

Source: RCPCH; BNFc; paediatric cardiology