Key Facts

Ventricular septal defect (VSD) is a congenital defect in the interventricular septum allowing communication between the left and right ventricles. It is the most common congenital heart defect.

Epidemiology

• Most common CHD: ~25-30% of all congenital heart defects
• Incidence: ~2-5 per 1,000 live births
• Equal sex distribution
• ~60-70% of small muscular VSDs close spontaneously by age 10

Types

• Perimembranous (membranous) (~70-80%): adjacent to aortic and tricuspid valves; most common type
• Muscular (~15-20%): within the muscular septum; multiple ('Swiss cheese') or single; highest spontaneous closure rate
• Outlet (supracristal/subpulmonary) (~5-8%): near the pulmonary valve; higher in Asian populations; risk of aortic valve prolapse
• Inlet (~5%): posterior septum near AV valves; associated with AVSD and Down syndrome

Pathophysiology

• LV pressure > RV pressure → left-to-right shunt through VSD
• Small (restrictive) VSD: high velocity jet through small defect; minimal haemodynamic effect; loud murmur (Maladie de Roger)

Small VSD

• Usually asymptomatic
• Loud pansystolic murmur heard incidentally
• Thrill at left sternal edge
• Normal growth and development

Large VSD (infants)

• Heart failure symptoms: poor feeding, failure to thrive, sweating with feeds, tachypnoea
• Recurrent chest infections
• Hepatomegaly
• Failure to gain weight

Examination Findings

• Harsh pansystolic murmur at left lower sternal edge with thrill
• Louder murmur paradoxically indicates smaller defect (higher velocity jet)
• Soft or absent murmur in very large VSD (equalised pressures)
• Displaced apex (LV volume overload in large VSD)
• Parasternal heave (RV overload)
• Signs of heart failure in large VSD: tachypnoea, hepatomegaly, gallop rhythm
• In Eisenmenger: murmur disappears, cyanosis, clubbing, loud P2

Red Flags

• Failure to thrive in infant with murmur
• Signs of heart failure
• New aortic regurgitation (outlet VSD with aortic cusp prolapse)
• Disappearance of murmur with worsening symptoms (Eisenmenger development)
• Endocarditis symptoms (fever, new murmur change)

Bedside

• ECG: normal in small VSD; biventricular hypertrophy in large; LAD + LVH; RAD + RVH in Eisenmenger
• CXR: normal in small VSD; cardiomegaly + pulmonary plethora in large; pruning of peripheral vessels in Eisenmenger
• Pulse oximetry: normal unless Eisenmenger (differential cyanosis)

Bloods

• BNP/NT-proBNP: elevated in significant shunt with heart failure
• Routine: FBC, U&Es

Imaging

• Transthoracic echocardiography: VSD location, size, shunt direction and velocity, LV/RV dimensions, PA pressure estimation, associated lesions (aortic cusp prolapse in outlet VSD)
• Cardiac MRI: Qp:Qs quantification, ventricular volumes (if echo suboptimal)
• Cardiac catheterisation: definitive haemodynamic assessment; calculate Qp:Qs, pulmonary vascular resistance; assess operability if pulmonary hypertension present

Special Tests

• Qp:Qs ratio: measures shunt magnitude
  • <1.5:1 → small, usually no intervention needed
  • 1.5-2:1 → moderate, monitor closely

  • 2:1 → large, surgical closure indicated

• Pulmonary vascular resistance: if elevated and fixed, surgical closure contraindicated (Eisenmenger)

Non-pharmacological

• Small VSD: observation, serial echo (annually initially, then less frequently)
• Calorie-dense feeds for infants with heart failure
• Dental hygiene education

Pharmacological

• Heart failure in infants: furosemide 1-2mg/kg/day, captopril 0.5-2mg/kg/day divided TDS
• Supplemental nutrition: high-calorie formula
• Endocarditis prophylaxis: not routinely recommended by NICE; only if previous endocarditis or prosthetic material
• Eisenmenger: pulmonary vasodilators (bosentan, sildenafil)

Surgical/Interventional

• Surgical patch closure: gold standard for large VSDs
  • Indicated: Qp:Qs >2:1 with LV volume overload; heart failure unresponsive to medical therapy; failure to thrive; outlet VSD with aortic cusp prolapse
  • Timing: usually within first 6-12 months if symptomatic; earlier if refractory HF
  • Operative mortality: <2% in experienced centres
• Transcatheter device closure: increasingly used for selected muscular and perimembranous VSDs
  • Best for muscular VSDs (especially residual post-surgical VSDs)
  • Risk of complete heart block with perimembranous VSD closure devices
• PA banding: rarely used; palliative in complex cases before definitive repair
• Closure CONTRAINDICATED in Eisenmenger syndrome

Referral Criteria

• All VSDs detected on echocardiography: paediatric/congenital cardiology referral
• Symptomatic or large VSD: surgical assessment
• Adults with VSD: grown-up congenital heart disease (GUCH) specialist
• Eisenmenger syndrome: specialist pulmonary hypertension centre

• Small VSD: excellent prognosis; spontaneous closure in ~60-70% of muscular and ~30-40% of perimembranous VSDs by age 10
• Post-surgical closure: excellent long-term outcomes; >95% survival at 20 years
• Surgical mortality: <2% for isolated VSD repair
• Large unrepaired VSD: Eisenmenger syndrome develops in ~50% by age 20-30
• Eisenmenger syndrome: poor prognosis; median survival ~40 years
• Late complications post-repair: residual VSD, heart block (~1-2%), endocarditis, aortic regurgitation
• Adults with small unrepaired VSD: near-normal life expectancy; small ongoing endocarditis risk

VSD Types Comparison

Indications for VSD Closure