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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
Key points
- CHD affects ~8 per 1,000 live births. Most common: VSD (30%), ASD (10%), PDA
- Acyanotic (left→right shunts): ASD (fixed split S2), VSD (pansystolic murmur at LLSE), PDA (continuous machinery murmur)
- Cyanotic (right→left shunts): Tetralogy of Fallot (most common cyanotic CHD — VSD + RV outflow obstruction + overriding aorta + RVH)
- Coarctation of aorta: upper limb hypertension, radio-femoral delay, rib notching on CXR
- Eisenmenger syndrome: chronic left→right shunt → pulmonary hypertension → shunt reversal (right→left) → cyanosis. Once established, surgery is contraindicated
Overview
Congenital heart disease (CHD) encompasses a diverse group of structural cardiac abnormalities present at birth. They are broadly classified as acyanotic (maintained systemic oxygenation, typically left-to-right shunts) or cyanotic (systemic desaturation, right-to-left shunts). Acyanotic lesions include ASD, VSD, PDA, and coarctation. Cyanotic lesions include Tetralogy of Fallot, transposition of the great arteries, and tricuspid atresia. Advances in paediatric cardiac surgery mean that >85% of children with CHD now survive to adulthood, creating a large and growing population of adults with CHD (ACHD) who require lifelong follow-up.
Epidemiology
CHD is the most common congenital abnormality, affecting approximately 8 per 1,000 live births. VSD is the most common individual lesion (~30% of all CHD), followed by ASD (~10%). Tetralogy of Fallot is the most common cyanotic CHD. Risk factors include genetic syndromes (Down syndrome — AVSD; Turner syndrome — coarctation; DiGeorge/22q11 — truncus arteriosus, ToF), maternal diabetes, maternal rubella, alcohol, and drugs (sodium valproate, lithium). Most cases are multifactorial.
Clinical Features
Symptoms
Many detected on antenatal ultrasound or newborn screening
ASD: often asymptomatic in childhood, presents with dyspnoea, palpitations (AF), or stroke (paradoxical embolism) in adulthood
VSD: small = asymptomatic with loud murmur; large = heart failure in infancy (failure to thrive, tachypnoea, feeding difficulty)
PDA: bounding pulses, continuous machinery murmur; large PDA → heart failure
Tetralogy of Fallot: cyanotic spells (tet spells) — infant goes blue, often during crying or feeding; squatting relieves symptoms (increases SVR)
Coarctation: headache, epistaxis, claudication in legs, may present with hypertension in young adults
Signs
ASD: fixed split S2 (does not vary with respiration), ejection systolic murmur at pulmonary area (increased flow through pulmonary valve)
VSD: pansystolic murmur at lower left sternal edge, loud with small VSD (restrictive), quiet with large VSD (unrestrictive)
PDA: continuous machinery murmur best heard below left clavicle, bounding pulses, wide pulse pressure
Tetralogy of Fallot: cyanosis, clubbing, ejection systolic murmur (RVOT obstruction), boot-shaped heart on CXR
Coarctation: hypertension in upper limbs, weak femoral pulses, radio-femoral delay, systolic murmur over left scapula
Investigations
First-line
EchocardiographyConfirms anatomy and haemodynamics for all CHD. TTE usually sufficient; TOE for ASD assessment in adults
ECGASD: RBBB + right axis (secundum) or RBBB + left axis (primum). VSD: LVH if large. ToF: RVH, right axis. Coarctation: LVH
Pulse oximetryPre- and post-ductal saturations in neonates (>3% difference suggests duct-dependent circulation or PDA)
Second-line
Chest X-rayASD: pulmonary plethora, enlarged RA/RV. VSD: pulmonary plethora, cardiomegaly if large. ToF: boot-shaped heart, oligaemic lung fields. Coarctation: rib notching (from collateral intercostal arteries), figure-of-3 sign
Cardiac MRIComprehensive anatomical and functional assessment — gold standard for ACHD follow-up, quantification of shunts (Qp:Qs)
Specialist
Cardiac catheterisationHaemodynamic assessment, measure shunt (Qp:Qs), assess pulmonary vascular resistance (before surgical/device closure), intervention (ASD/PDA device closure, coarctation stenting)
CT angiographyAortic arch anatomy (coarctation), coronary anatomy pre-surgery
1
ASD
- Percutaneous device closure (catheter-based) for secundum ASD with significant left-to-right shunt (Qp:Qs >1.5:1)
- Surgical closure for primum ASD, sinus venosus ASD, or unsuitable anatomy for device
- Small ASD with no significant shunt may be observed
2
VSD
- Small restrictive VSD: often closes spontaneously in childhood — observe
- Large VSD with heart failure: medical management (diuretics, ACEi), then surgical closure (usually before age 1)
- Transcatheter device closure increasingly available for suitable muscular VSDs
3
PDA
- Premature neonates: trial of ibuprofen or paracetamol (promotes ductal closure)
- Surgical ligation or transcatheter device closure if haemodynamically significant
4
Tetralogy of Fallot
- Acute tet spell: knee-to-chest position, oxygen, IV morphine, IV fluids, IV phenylephrine (increase SVR)
- Definitive: surgical repair (close VSD + relieve RVOT obstruction) — usually at 4–6 months of age
- Lifelong follow-up for pulmonary regurgitation (late complication of repair), arrhythmias, and RV dysfunction
5
Coarctation of aorta
- Neonates (duct-dependent): prostaglandin E1 infusion to maintain PDA patency → surgical repair
- Older children/adults: balloon angioplasty + stenting (preferred) or surgical repair
- Lifelong BP monitoring (re-coarctation and persistent hypertension common)
6
Eisenmenger syndrome
- Once Eisenmenger develops, closure of the shunt is CONTRAINDICATED (the shunt is now acting as a pressure relief valve)
- Manage with PAH-targeted therapies (bosentan — BREATHE-5 trial), oxygen, phlebotomy if symptomatic polycythaemia
- Heart-lung transplantation or lung transplant + repair of cardiac defect for end-stage
Complications
- Eisenmenger syndrome: Irreversible pulmonary hypertension from chronic left-to-right shunt → shunt reversal → cyanosis
- Infective endocarditis: All unrepaired and many repaired CHD lesions carry IE risk
- Arrhythmias: AF (ASD), VT (post-ToF repair), heart block (post-VSD repair)
- Heart failure: Volume overload (shunts), pressure overload (obstructions)
- Paradoxical embolism: Through ASD or PFO → stroke in young adults
- Pulmonary vascular disease: From chronic overcirculation
UKMLA Exam Tips
- 1Fixed split S2 = ASD (classic exam finding — S2 does not vary with respiration)
- 2Pansystolic murmur at LLSE = VSD (contrast with MR at apex and TR louder on inspiration)
- 3Continuous machinery murmur below left clavicle = PDA
- 4Cyanotic infant squatting for relief = Tetralogy of Fallot (increases SVR → reduces right-to-left shunting)
- 5Radio-femoral delay + upper limb hypertension in a young person = coarctation
- 6Rib notching on CXR = coarctation (dilated intercostal collateral arteries eroding ribs)
- 7Down syndrome = AVSD (atrioventricular septal defect) — the classic genetic association
- 8Eisenmenger: closure contraindicated once shunt reverses — irreversible
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