Congenital heart disease

Overview

Heart defects are the commonest birth defect, affecting roughly 1% of babies. Better surgery means most children now reach adult life, so physicians meet both unrepaired defects (often ASD, small VSD, PDA, coarctation) and repaired ones (Fallot, transposition).

For MCQs, learn each lesion as a set: direction of shunt, murmur, X-ray, ECG, treatment, and when the window for closure closes (Eisenmenger syndrome).

Classification

Associations worth remembering

• Maternal rubella: PDA and VSD (with cataract, deafness).
• Turner syndrome: coarctation of the aorta.
• Down syndrome: atrioventricular septal (endocardial cushion) defects.
• 22q11 deletion (DiGeorge): conotruncal defects such as tetralogy of Fallot.
• Maternal lupus (anti-Ro): congenital complete heart block.
• Prematurity: persistent PDA.

Ventricular septal defect (VSD)

The most common congenital heart defect. Left ventricular pressure is higher, so blood shunts left to right into the right ventricle and lungs.

Size decides the picture

• Small (restrictive) VSD ("maladie de Roger"): fast jet, small volume, no strain on the heart. The murmur is loud, but the patient is well. Most close on their own by about 10 years.
• Moderate VSD: volume load returns to the left side, so the left atrium and left ventricle dilate; this is an indication to close it.
• Large (non-restrictive) VSD: heart failure in infancy, then pulmonary vascular damage. When right-sided pressure rises above left, the shunt reverses: Eisenmenger syndrome.

Clinical features

• Harsh pansystolic murmur at the left sternal edge, often with a thrill.
• As pulmonary pressure rises, the murmur becomes softer and P2 becomes loud.

Investigations and treatment

• Small VSD: X-ray and ECG usually normal. Echocardiography confirms the site and size.
• Closure (surgery or a catheter device) is offered for a significant shunt with left heart dilation, provided pulmonary hypertension is still reversible.
• Small defects need only follow-up; the main risk is infective endocarditis.
• Surgical repair of a perimembranous VSD can damage the nearby conduction tissue, causing complete heart block.

Atrial septal defect (ASD)

Often missed until adult life, because children have few symptoms and the signs are soft.

Types

Haemodynamics

The left-to-right shunt overloads the right atrium and right ventricle with volume. Adults present with breathlessness, reduced exercise tolerance, or atrial arrhythmia (often atrial fibrillation or flutter). Severe pulmonary vascular disease is uncommon (under 5%).

Signs and tests

• Wide, fixed splitting of S2 (does not vary with breathing).
• Ejection systolic flow murmur in the pulmonary area (from extra flow across a normal pulmonary valve, not from the hole itself).
• ECG: right bundle branch block with right axis deviation (secundum). RBBB with left axis deviation suggests an ostium primum defect.
• Chest X-ray: prominent pulmonary arteries, plethoric lungs, enlarged right heart.
• Echocardiography confirms; transoesophageal echo helps plan device closure.

Treatment

Close the defect if there is a significant shunt with right heart enlargement while pulmonary vascular resistance is still normal. Secundum defects with good rims are closed with a catheter device; other types need surgery.

Patent ductus arteriosus (PDA)

The ductus joins the descending aorta to the left pulmonary artery. It normally closes within hours of birth. It stays open more often in premature babies, with maternal rubella, and at high altitude (low oxygen keeps it open).

• Shunt: continuous aorta → pulmonary artery (left to right) in both systole and diastole.
• Continuous "machinery" murmur, best heard below the left clavicle, often with a thrill.
• Moderate shunt: bounding pulses, wide pulse pressure, displaced apex.
• Large shunt in an adult: pulmonary hypertension; the murmur fades; in Eisenmenger PDA the toes are bluer and more clubbed than the fingers (differential cyanosis).
• Treatment: in the newborn, indometacin (or ibuprofen), which inhibit prostaglandin, closes the duct. In adults, device closure if the shunt is significant.

Coarctation of the aorta

A narrowing of the aorta, usually just beyond the left subclavian artery near the ductus insertion.

• Associations: bicuspid aortic valve (about 80%), berry aneurysms of the circle of Willis (about 10%), Turner syndrome.
• Collateral circulation develops through the intercostal arteries.

Clinical features

• Often found as hypertension in a young adult, with headache or nosebleeds; severe cases have cold legs and claudication.
• Upper limb hypertension with weak, delayed femoral pulses (radio-femoral delay).
• Systolic murmur over the upper chest or back, and bruits from collaterals.

Investigations

• Chest X-ray: rib notching (from dilated intercostal collaterals) and the "3" sign of the aortic contour.
• ECG: left ventricular hypertrophy.
• CT or MRI shows the narrowing; MRI is preferred for follow-up (no radiation).

Treatment

Intervene when the gradient across the narrowing is more than 20 mmHg at catheter, or with marked narrowing plus hypertension or LVH. Neonates have surgery; older children and adults usually have balloon dilation and stenting. Blood pressure may stay high after repair, so lifelong follow-up is needed.

Tetralogy of Fallot

The commonest cyanotic defect seen after infancy. Four parts:

1. Large VSD (malaligned)
2. Overriding aorta
3. Right ventricular outflow tract obstruction (pulmonary stenosis)
4. Right ventricular hypertrophy

The severity of the outflow obstruction decides how blue the child is: more obstruction means more right-to-left flow through the VSD.

• Murmur: ejection systolic murmur from the outflow tract (not from the VSD); single S2 because P2 is too soft.
• Hypercyanotic ("tet") spells: sudden deep cyanosis from outflow spasm. Children squat, which raises systemic resistance and pushes more blood to the lungs.
• Chest X-ray: boot-shaped heart with oligaemic lung fields.
• Treatment: complete repair in childhood. Very sick infants may first get a Blalock-Taussig shunt (subclavian to pulmonary artery). Adults after repair often have pulmonary regurgitation needing valve replacement, and are at risk of arrhythmias and sudden death.

Transposition of the great arteries

The aorta arises from the right ventricle and the pulmonary artery from the left ventricle. The two circulations run in parallel, so the baby is cyanosed from birth and survives only through mixing at an ASD, VSD or PDA.

• Emergency: prostaglandin E to keep the duct open; balloon atrial septostomy (Rashkind) to improve mixing.
• Definitive: the arterial switch operation, now done in the first weeks of life. Older adults may have had an atrial switch, which leaves the right ventricle pumping to the body; it tends to fail with time.
• X-ray: "egg on a string" appearance.
• Congenitally corrected transposition: physiology is corrected, so no cyanosis, but it is linked with complete heart block, tricuspid regurgitation and WPW.

Eisenmenger syndrome

Definition: a large left-to-right shunt (VSD, PDA, less often ASD) causes pulmonary vascular remodelling and pulmonary hypertension; once right-sided pressure exceeds left, the shunt reverses to right to left.

• Features: central cyanosis, clubbing, polycythaemia, a loud P2, and a softer or absent murmur.
• ECG: right axis deviation and right ventricular hypertrophy.
• Closure of the defect is now contraindicated; the defect acts as a safety valve for the right ventricle. Management is supportive; the definitive option is heart-lung transplantation.
• Pregnancy carries a very high maternal risk and is advised against.

Long-term issues in adults

• Infective endocarditis risk (especially VSD, PDA, repaired defects with residual leaks).
• Atrial arrhythmias (ASD, repaired Fallot, atrial switch).
• Heart failure of the systemic ventricle.
• Pregnancy counselling and specialist follow-up.

Quick revision

• VSD: commonest; harsh pansystolic murmur at left sternal edge; small ones close spontaneously.
• ASD: secundum commonest; fixed wide split S2; RBBB; primum has left axis deviation.
• PDA: continuous machinery murmur; bounding pulse; indometacin closes, prostaglandin E opens.
• Coarctation: young hypertensive, radio-femoral delay, rib notching, bicuspid aortic valve, Turner syndrome.
• Fallot: VSD, overriding aorta, RV outflow obstruction, RVH; squatting; boot-shaped heart.
• Transposition: blue at birth; prostaglandin E, septostomy, arterial switch.
• Eisenmenger: shunt reversal, cyanosis, loud P2; do not close the defect.

Written by The House Job from standard references (Kumar and Clark's Clinical Medicine).

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