Cardiology: Congenital Heart Disease (Complete)

• Related Subjects: |Heart Failure |Cardiac Resynchronisation
• Basics: What Is Congenital Heart Disease? | Fetal Circulation and Changes at Birth | Causes and Associations | Genetic Syndromes | Classifying CHD | Detection and Screening | Presentation by Age | Innocent Murmurs | Investigations
• Neonatal emergencies: The Cyanosed Newborn | The Shocked Newborn | Duct-dependent Lesions and Prostaglandin | Heart Failure in Infants
• Left-to-right shunts: Atrial Septal Defect (ASD) | Patent Foramen Ovale (PFO) | Ventricular Septal Defect (VSD) | Atrioventricular Septal Defect (AVSD) | Patent Ductus Arteriosus (PDA)
• Obstructive lesions: Coarctation of the Aorta | Congenital Aortic Stenosis | Pulmonary Stenosis
• Cyanotic lesions: Tetralogy of Fallot | Transposition of the Great Arteries | Congenitally Corrected Transposition | Tricuspid Atresia and Single Ventricle | Hypoplastic Left Heart Syndrome | Total Anomalous Pulmonary Venous Drainage | Truncus Arteriosus | Ebstein Anomaly
• Adults with CHD: Eisenmenger Syndrome | The Fontan Circulation | Adult Congenital Heart Disease (ACHD) | Pregnancy and Contraception | Endocarditis, Exercise and Lifestyle
• Treatment overview: Surgery and Catheter Interventions
• Revision: Drug Reference Table | Spot the Diagnosis | Exam-style Scenarios | Key Points | Guidelines and Further Reading

🫀 Congenital heart disease (CHD) is a structural abnormality of the heart or great vessels that is present from birth. It is the commonest congenital abnormality, affecting about 8 in every 1,000 babies. Thanks to surgery, over 90% of affected children now reach adulthood, so there are now more adults than children living with CHD in the UK.
Your four questions for every patient: Is blood shunting (and which way)? Is something obstructed? Is the patient cyanosed? Has it been repaired, and what problems does the repair leave behind?

What Is Congenital Heart Disease?

CHD covers everything from a tiny hole that closes on its own to a heart with only one working pumping chamber. Most lesions are combinations of three basic problems:

• A hole (shunt): Blood passes between the left and right sides, e.g. ASD, VSD, PDA.
• A narrowing (obstruction): Blood flow is blocked, e.g. coarctation, aortic stenosis, pulmonary stenosis.
• Wrong connections: Chambers or vessels are joined to the wrong place, e.g. transposition, anomalous pulmonary veins.

Why it matters:

• In babies: Some lesions are emergencies within hours or days of birth, when the fetal circulation closes down.
• In children: Heart failure, failure to thrive, cyanosis and murmurs.
• In adults: Repaired hearts are not "cured". Arrhythmias, heart failure, valve problems, pulmonary hypertension and pregnancy risks continue for life.

The most common lesions:

• VSD: About 30%.
• ASD and PDA: About 7–10% each.
• Pulmonary stenosis, coarctation and tetralogy of Fallot: About 5% each.
• TGA: About 5%.
• Bicuspid aortic valve: Affects 1–2% of all people but is often counted separately.

💡 Clinical Pearl: "Repaired" is not "cured". Every adult with moderate or complex CHD needs lifelong follow-up in a specialist ACHD service.

↑ Back to index

Fetal Circulation and Changes at Birth

You cannot understand neonatal CHD without the fetal circulation. Before birth the lungs are filled with fluid and do no work, because oxygen comes from the placenta. Three shunts divert blood away from the lungs:

• Ductus venosus: Carries oxygenated blood from the umbilical vein past the liver into the inferior vena cava.
• Foramen ovale: A flap between the atria. Oxygenated blood crosses from the right to the left atrium and goes to the brain.
• Ductus arteriosus: Connects the pulmonary artery to the aorta, so most right ventricular output bypasses the lungs.

What happens at birth:

• First breaths: The lungs expand and pulmonary vascular resistance falls sharply, so blood flows into the lungs.
• Foramen ovale closes: More blood returns from the lungs, so left atrial pressure exceeds right atrial pressure and pushes the flap shut. In about 25% of people it never seals completely (patent foramen ovale).
• Ductus arteriosus closes: Rising oxygen levels and falling prostaglandins (the placenta was a major source) make it constrict. It closes functionally within 1–3 days and permanently within 2–3 weeks.
• Pulmonary resistance keeps falling: This continues over the first 4–8 weeks of life.

Why this explains when CHD presents:

• Duct-dependent lesions collapse when the duct closes, typically at day 2–7. The baby becomes shocked or deeply cyanosed.
• Large left-to-right shunts (big VSD, AVSD, PDA) become symptomatic at 4–8 weeks. As pulmonary resistance falls, more blood floods into the lungs, causing heart failure.

💡 Key concept: A baby with a big VSD often looks well at birth and at the first check. The murmur and heart failure appear weeks later as pulmonary resistance falls.

↑ Back to index

Causes and Associations

Most CHD is multifactorial - a mix of genetic susceptibility and environment. A cause is identified in a minority.

• Chromosomal and genetic syndromes: Down, Turner, 22q11 deletion (DiGeorge), Williams, Noonan, Marfan, Holt–Oram (see Genetic Syndromes).
• Maternal illness:
  • Poorly controlled diabetes: TGA, VSD, and thickening of the septum.
  • Lupus with anti-Ro/La antibodies: Congenital complete heart block.
  • Phenylketonuria.
  • Rubella infection: PDA and pulmonary artery stenosis, with cataracts and deafness.
• Drugs and toxins in pregnancy:
  • Alcohol: VSD and ASD.
  • Lithium: Ebstein anomaly (a weak association).
  • Valproate and phenytoin.
  • Warfarin: Embryopathy.
  • Isotretinoin.
• Family history: If one parent or sibling has CHD, the risk for the next child is about 3–5%. It is higher if the mother is the one affected, and up to 50% in single-gene syndromes.

↑ Back to index

Genetic Syndromes

Syndrome-lesion pairings are a favourite exam topic:

💡 Clinical Pearl: Every baby with Down syndrome should have an echocardiogram in the first weeks of life. An AVSD can be silent at birth but cause heart failure and irreversible pulmonary hypertension within months.

↑ Back to index

Classifying CHD

A simple framework sorts almost every lesion:

The "5 Ts" of cyanotic CHD:

• Tetralogy of Fallot.
• Transposition of the great arteries.
• Tricuspid atresia.
• Truncus arteriosus.
• Total anomalous pulmonary venous drainage.

Severity grading in adults (ESC):

• Mild: E.g. a small ASD, or a repaired PDA.
• Moderate: E.g. repaired tetralogy, coarctation, Ebstein anomaly.
• Severe: E.g. Fontan circulation, cyanotic disease, Eisenmenger syndrome, transposition.

The grade determines how often and where patients are followed up.

↑ Back to index

Detection and Screening

• Antenatal:
  • The 20-week fetal anomaly scan (18+0 to 20+6 weeks) includes standard views of the heart.
  • Fetal echocardiography for high-risk pregnancies: family history, maternal diabetes, abnormal scan or genetic findings.
  • Antenatal diagnosis lets the baby be delivered near a cardiac centre, with prostaglandin ready if needed.
• Newborn examination: The NIPE check within 72 hours, repeated at 6–8 weeks. It covers:
  • Colour, breathing and heart sounds.
  • Femoral pulses - absent or weak femorals suggest coarctation.
• Pulse oximetry screening: Some units use it to detect low saturations from critical CHD before symptoms.
• Limits of screening: Many lesions are still missed antenatally and at the first newborn check. The key ones are coarctation and duct-dependent lesions, which may appear normal until the duct closes.

💡 Clinical Pearl: Always feel the femoral pulses in a baby. Missed coarctation is a classic cause of a collapsed baby at 1–2 weeks old.

↑ Back to index

Presentation by Age

Symptoms of heart disease in a baby:

• Feeding difficulty: Poor feeding, sweating during feeds, tiring before finishing a feed.
• Breathing: Fast breathing and grunting.
• Growth: Failure to thrive.
• Colour: Pallor, mottling or a blue colour.

↑ Back to index

Innocent Murmurs

Up to half of all children have a murmur at some point, and most are innocent. These come from normal blood flow through a normal heart, often heard during fever or anaemia. Recognising them avoids unnecessary referrals.

Features of an innocent murmur - the "S"s:

• Soft (grade 1–2, no thrill).
• Systolic (never diastolic).
• Short.
• Sternal edge (left).
• Symptom-free child.
• Sensitive to posture (changes when the child sits up or lies down).
• Normal heart sounds.

Common types:

• Still's murmur: A musical, vibratory systolic murmur at the lower left sternal edge, in children aged 2–7.
• Venous hum: A continuous murmur below the clavicles. It disappears when the child lies flat or when the neck veins are gently compressed.
• Pulmonary flow murmur: A soft ejection murmur at the upper left sternal edge.

Refer for echo if:

• Diastolic murmur, loud murmur (grade 3 or more), thrill or radiation.
• Abnormal heart sounds (e.g. fixed split S2, click).
• Symptoms, poor growth or cyanosis.
• Abnormal pulses (absent femorals).
• Any murmur in a neonate or a child with a syndrome.

↑ Back to index

Investigations

• Pulse oximetry: Check pre-ductal (right hand) and post-ductal (either foot) saturations. A difference of more than 3% suggests a right-to-left shunt through the duct.
• Four-limb blood pressure: Arm BP well above leg BP suggests coarctation.
• ECG: Axis and hypertrophy are key clues:
  • Left axis deviation: AVSD or primum ASD, tricuspid atresia.
  • Right axis deviation with RBBB: Secundum ASD.
  • Right ventricular hypertrophy: Tetralogy, PS, pulmonary hypertension.
  • Pre-excitation: Ebstein anomaly.
  • Complete heart block: Maternal lupus, congenitally corrected TGA.
• Chest X-ray: Heart size, lung blood flow (plethoric or oligaemic lung fields) and classic shapes:
  • Boot-shaped heart: tetralogy of Fallot.
  • Egg on a string: TGA.
  • Snowman: supracardiac TAPVD.
  • Rib notching and a "3" sign: coarctation.
• Hyperoxia (nitrogen washout) test: Give 100% oxygen to a cyanosed newborn. A large rise in arterial oxygen suggests lung disease; little or no rise suggests a fixed cardiac shunt. It is now largely replaced by urgent echo.
• Echocardiography: The key test. It defines the anatomy, shunt direction, valves, ventricular function and pressures. TOE is used in adults.
• Cardiac MRI and CT: Anatomy of the great vessels and ventricular volumes. MRI is the mainstay of adult follow-up, e.g. RV size after tetralogy repair.
• Cardiac catheterisation: Measures pressures and pulmonary vascular resistance before surgery or transplant, and allows interventions (balloon, stent, device closure).
• Genetic testing: Microarray or targeted tests if a syndrome is suspected.

↑ Back to index

The Cyanosed Newborn

Central cyanosis (blue tongue and lips, saturations below about 95%) in a newborn needs urgent assessment. The causes fall into four groups:

• Cardiac: TGA, pulmonary atresia, critical PS, severe tetralogy, tricuspid atresia, TAPVD, truncus, HLHS.
• Respiratory: Respiratory distress syndrome, pneumonia, meconium aspiration, pneumothorax, diaphragmatic hernia.
• Persistent pulmonary hypertension of the newborn (PPHN): Pulmonary resistance fails to fall after birth.
• Other: Sepsis, methaemoglobinaemia, hypoglycaemia.

Clues that the cause is cardiac:

• Cyanosis without much respiratory distress - a "comfortably blue" baby.
• Little improvement with oxygen.
• A murmur (although many cyanotic lesions have no murmur).
• Abnormal pulses.
• Cardiomegaly or abnormal lung blood flow on X-ray.

Management:

• Resuscitate (ABC).
• Pre- and post-ductal saturations; blood gas, glucose, cultures.
• Chest X-ray and urgent echo.
• Discuss with the regional paediatric cardiology centre.
• If a duct-dependent lesion is suspected, start prostaglandin without waiting for the echo.

💡 Clinical Pearl: A cyanosed newborn who is not breathing hard is likely to have heart disease. A blue baby working hard to breathe is more likely to have lung disease.

↑ Back to index

The Shocked Newborn

Mechanism: In left-sided obstructive lesions, blood reaches the body through the ductus arteriosus. When the duct closes (usually day 2–7), systemic blood flow collapses.

Causes:

• Hypoplastic left heart syndrome.
• Critical coarctation.
• Critical aortic stenosis.
• Interrupted aortic arch.

Clinical pattern:

• A baby who was well at discharge becomes grey, mottled and breathless, with poor feeding.
• On examination: weak or absent femoral pulses, hepatomegaly, metabolic acidosis, oliguria.
• It looks identical to sepsis.

Management:

• ABC resuscitation; treat for sepsis at the same time (cultures, antibiotics).
• Start a prostaglandin infusion to reopen the duct.
• Correct acidosis and glucose; inotropes if needed.
• Urgent echo and transfer to a cardiac centre.

⚠️ Safety Pearl: In any collapsed baby in the first two weeks, feel the femoral pulses and think "duct-dependent heart disease". Treat with both antibiotics and prostaglandin until echo clarifies.

↑ Back to index

Duct-dependent Lesions and Prostaglandin

A duct-dependent lesion is one in which the baby survives only while the ductus arteriosus is open. There are three types:

• Duct-dependent pulmonary blood flow: The duct supplies the lungs. Pulmonary atresia, critical PS, tricuspid atresia, severe tetralogy. Presents with cyanosis.
• Duct-dependent systemic blood flow: The duct supplies the body. HLHS, critical coarctation or AS, interrupted arch. Presents with shock.
• Duct-dependent mixing: TGA. The duct (and foramen ovale) allow oxygenated blood to reach the body. Presents with profound cyanosis.

Prostaglandin E (alprostadil or dinoprostone) infusion: Keeps the duct open, or reopens it, until surgery or a catheter procedure.

• Dosing: Start at a low dose (around 5–10 nanograms/kg/min) and titrate to response, using higher doses in a collapsed baby with a closing duct. Follow the regional neonatal cardiac protocol and BNFc.
• Side effects:
  • Apnoea (especially at higher doses) - be ready to ventilate, particularly for transfer.
  • Fever, flushing, hypotension.
  • Jitteriness.

💡 Clinical Pearl: If in doubt, start prostaglandin. The risk of giving it unnecessarily is small; the risk of withholding it from a duct-dependent baby is death.

↑ Back to index

Heart Failure in Infants

Mechanism: Usually caused by a large left-to-right shunt (VSD, AVSD, PDA). Excess lung blood flow makes the lungs stiff and wet and overloads the heart. Less commonly it is due to obstruction, cardiomyopathy or arrhythmia.

Clinical pattern (often at 4–8 weeks):

• Breathlessness and sweating during feeds; feeds take a long time.
• Failure to thrive.
• Tachypnoea and tachycardia.
• Hepatomegaly - the most reliable sign of fluid overload in infants (ankle oedema and a raised JVP are rarely seen).
• Recurrent chest infections.

Management:

• Nutrition: High-energy feeds, often via a nasogastric tube.
• Diuretics: Furosemide, usually combined with spironolactone.
• Afterload reduction: Sometimes an ACE inhibitor (captopril), under specialist supervision.
• Definitive repair: Surgical or catheter closure of the defect, usually within the first months - before irreversible pulmonary vascular disease develops.

↑ Back to index

Atrial Septal Defect (ASD)

Mechanism: A hole in the atrial septum lets blood flow from the left atrium to the right atrium. The right atrium, RV and lungs are volume-loaded. Because the pressure difference between the atria is small, symptoms usually appear only in adulthood, often in the 30s–40s.

Types:

• Secundum (about 70–80%): In the middle of the septum. Suitable for catheter device closure.
• Primum: Low in the septum; part of the AVSD spectrum, with a cleft mitral valve. Associated with Down syndrome.
• Sinus venosus: High, near the superior vena cava, often with anomalous pulmonary veins draining into the right atrium.

Clinical pattern:

• Usually asymptomatic in childhood.
• In adults: exertional breathlessness, palpitations or AF.
• Paradoxical embolism (stroke).
• Right heart failure; pulmonary hypertension if large and untreated.

Signs:

• Fixed, widely split S2 - the classic sign. The extra RV volume delays pulmonary valve closure on every beat, whatever the breathing phase.
• Ejection systolic "flow" murmur at the upper left sternal edge. This comes from extra blood crossing the pulmonary valve, not from blood crossing the ASD.
• RV heave.

ECG:

• Secundum: RBBB with right axis deviation.
• Primum: RBBB with left axis deviation.

Management: Close the defect if the right heart is enlarged and pulmonary vascular resistance is not too high.

• Secundum: Percutaneous device closure.
• Primum and sinus venosus: Surgery.
• Timing: Closure is best done in childhood, but it still benefits adults. Closure is contraindicated once Eisenmenger physiology has developed.

💡 MRCP Pearl: Fixed split S2 + ejection systolic murmur + RBBB in a breathless 40-year-old with new AF = secundum ASD.

↑ Back to index

Patent Foramen Ovale (PFO)

Mechanism: The fetal flap between the atria fails to seal after birth. It is present in about 25% of adults. Unlike an ASD, no tissue is missing, and there is normally no shunt. However, the flap can open when right atrial pressure rises briefly - coughing, straining, or the Valsalva manoeuvre.

Clinical significance: Usually none. Important associations:

• Paradoxical embolism: A venous clot crosses to the left side and causes a stroke. This is relevant in younger patients with "cryptogenic" stroke.
• Decompression illness: In divers.
• Platypnoea–orthodeoxia: Breathlessness and desaturation on sitting up.
• Migraine with aura: Associated, but closure is not routinely recommended for migraine.

Diagnosis: A "bubble study" - agitated saline injected IV during echo, with a Valsalva manoeuvre. Bubbles appearing in the left atrium within a few beats indicate a shunt.

Management: Most need nothing. PFO closure reduces recurrent stroke in selected patients (typically under 60) with a cryptogenic ischaemic stroke and a high-risk PFO, decided jointly by stroke and cardiology teams.

↑ Back to index

Ventricular Septal Defect (VSD)

Mechanism: A hole in the ventricular septum - the commonest congenital lesion. In systole, blood is driven at high pressure from the LV into the RV and lungs. The size of the hole determines what happens:

• Small (restrictive) VSD: Little flow, but a high-velocity jet, so the murmur is loud. Usually asymptomatic. Many muscular VSDs close spontaneously in childhood. Historically called maladie de Roger.
• Large VSD: Pressures equalise, so the murmur may be quiet. Lung blood flow is greatly increased, causing heart failure at 4–8 weeks. Without repair, irreversible pulmonary vascular disease develops within 1–2 years, leading to Eisenmenger syndrome.

Types:

• Perimembranous (commonest): Near the aortic valve.
• Muscular: Often multiple; often close spontaneously.
• Outlet: Can cause aortic valve prolapse and aortic regurgitation.

Signs:

• Harsh pansystolic murmur at the lower left sternal edge, often with a thrill.
• In large VSDs: signs of heart failure, a loud P2 (pulmonary hypertension), and an apical mid-diastolic murmur from increased flow across the mitral valve.

Management:

• Small VSD: Observe; good dental hygiene (endocarditis risk).
• Large VSD: Treat heart failure (diuretics, nutrition), then surgical closure, usually by 3–6 months of age.
• Adult VSD: Close if the LV is volume-loaded, if there has been endocarditis or aortic valve prolapse, and pulmonary resistance is acceptable.
• After MI: A VSD can also be acquired from septal rupture (see IHD chapter).

💡 Clinical Pearl: In VSD, a loud murmur usually means a small hole. A large hole with high pulmonary pressure may have only a soft murmur - or none once Eisenmenger syndrome develops.

↑ Back to index

Atrioventricular Septal Defect (AVSD)

Mechanism: The central part of the heart - the "crux", where the atrial and ventricular septa meet the AV valves - fails to form. The complete form has:

• A primum ASD.
• An inlet VSD.
• A single common AV valve instead of separate mitral and tricuspid valves, which often leaks.

A partial AVSD is a primum ASD with a cleft mitral valve.

Association: Strongly linked with Down syndrome.

Clinical pattern: Complete AVSD causes heart failure in early infancy, and pulmonary hypertension develops rapidly, especially in Down syndrome.

ECG: Superior axis (left axis deviation) - a key clue, because the conduction system is displaced.

Management: Heart failure treatment, then surgical repair at about 3–6 months. Long-term issues are AV valve regurgitation (especially left-sided) and heart block.

💡 MRCP Pearl: Down syndrome + left axis deviation on ECG = AVSD until proven otherwise.

↑ Back to index

Patent Ductus Arteriosus (PDA)

Mechanism: The ductus arteriosus fails to close after birth, so blood flows from the aorta into the pulmonary artery throughout both systole and diastole (aortic pressure is always higher). This volume-loads the left atrium and LV.

Risk factors: Prematurity (very common in preterm babies), congenital rubella, high altitude, female sex.

Signs:

• Continuous "machinery" murmur below the left clavicle.
• Bounding pulses and a wide pulse pressure - blood "runs off" into the lungs during diastole.
• In large PDAs: heart failure, and difficulty weaning preterm babies from the ventilator.

Management:

• Preterm babies: Drugs that inhibit prostaglandin can close the duct - ibuprofen, indometacin or paracetamol. Surgical ligation if this fails.
• Term babies, children and adults: A PDA will not close spontaneously. Catheter device or coil closure for a significant PDA, to prevent heart failure, endocarditis and pulmonary hypertension. A tiny silent duct may simply be observed.
• Large PDA left untreated: Eisenmenger syndrome causes differential cyanosis - blue, clubbed toes with pink fingers, because the deoxygenated blood enters the aorta beyond the arm arteries.

💡 Clinical Pearl: Prostaglandin opens the duct (for duct-dependent lesions); ibuprofen or indometacin closes it (for PDA in preterm babies).

↑ Back to index

Coarctation of the Aorta

Mechanism: A narrowing of the aorta, usually just beyond the left subclavian artery, near where the ductus arteriosus inserts. The upper body receives blood at high pressure and the lower body at low pressure. Collateral arteries (e.g. the intercostals) gradually enlarge to carry blood around the narrowing.

Associations:

• Bicuspid aortic valve (about half).
• Turner syndrome.
• VSD.
• Berry aneurysms in the brain.

Two presentations:

• Critical neonatal coarctation: The lower body depends on the duct. When it closes (day 2–14), the baby collapses with shock, acidosis and absent femoral pulses. Treat as a duct-dependent emergency with prostaglandin.
• Older child or adult: Often found because of hypertension in a young person, or a murmur. There may be headaches, nosebleeds, cold legs or leg claudication.

Signs:

• Radio-femoral delay and weak femoral pulses.
• BP higher in the arms than the legs, and often higher in the right arm.
• Systolic murmur at the back, between the shoulder blades.
• Murmurs over collateral vessels.
• Ejection click from an associated bicuspid valve.

Investigations:

• Chest X-ray: Rib notching (from enlarged intercostal collaterals, in older children and adults) and the "3" sign.
• Echo.
• Cardiac MRI or CT: To define the anatomy.

Management:

• Neonates: Surgical repair.
• Older children and adults: Balloon angioplasty with stenting, or surgery.
• Lifelong follow-up:
  • Persistent hypertension is common even after a good repair.
  • Re-narrowing (recoarctation) and aneurysm at the repair site.
  • Bicuspid valve disease.
  • Premature coronary disease and stroke.

💡 Clinical Pearl: Hypertension in a young adult - always check the femoral pulses and the BP in the legs.

↑ Back to index

Congenital Aortic Stenosis

Mechanism: Obstruction to LV outflow, causing LV pressure overload. The obstruction can be at one of three levels:

• Valvular (commonest): Usually a bicuspid or malformed valve.
• Subvalvular: A fibrous membrane below the valve.
• Supravalvular: A narrowing above the valve, classically in Williams syndrome.

Clinical pattern:

• Critical neonatal AS: A duct-dependent emergency, presenting with shock.
• Older children: Usually an asymptomatic murmur. In severe cases there may be exertional chest pain, syncope or sudden death.

Signs: Ejection systolic murmur at the upper right sternal edge, radiating to the neck; an ejection click (valvular AS); a slow-rising pulse in severe disease.

Management:

• Balloon valvuloplasty in infants and children.
• Surgery for subvalvular or supravalvular disease.
• The Ross procedure (the patient's own pulmonary valve moved to the aortic position) in selected young patients.
• Avoid competitive or strenuous sport if the stenosis is significant.

Bicuspid valves often progress to adult AS in the 50s–60s (see the valvular heart disease chapter).

↑ Back to index

Pulmonary Stenosis

Mechanism: A narrowing of the pulmonary valve or outflow tract causes RV pressure overload and hypertrophy. It is associated with Noonan syndrome (dysplastic valve), Williams syndrome (peripheral pulmonary artery stenoses), congenital rubella and tetralogy of Fallot.

Clinical pattern:

• Mild to moderate: Asymptomatic murmur.
• Severe: Exertional breathlessness, fatigue and RV failure.
• Critical neonatal PS: Duct-dependent cyanosis.

Signs:

• Ejection systolic murmur at the upper left sternal edge, louder on inspiration.
• Ejection click.
• RV heave.
• Soft, delayed P2.
• Prominent A waves in the JVP.

Management: Balloon pulmonary valvuloplasty is very effective for valvular PS; surgery for dysplastic valves. Mild PS needs only follow-up.

↑ Back to index

Tetralogy of Fallot

Mechanism: The commonest cyanotic CHD beyond the newborn period. A single developmental fault - the outflow septum is displaced forwards - produces four features:

• 1. Right ventricular outflow tract obstruction (pulmonary stenosis) - determines severity.
• 2. A large VSD.
• 3. An overriding aorta sitting above the VSD.
• 4. Right ventricular hypertrophy - a consequence of the obstruction.

The more severe the RV outflow obstruction, the more deoxygenated blood crosses the VSD into the aorta, and the bluer the child.

Associations: 22q11 deletion (DiGeorge), Down syndrome, a right-sided aortic arch.

Clinical pattern:

• Cyanosis in infancy, which may be mild at first ("pink tet").
• A loud ejection systolic murmur at the left sternal edge. This comes from the pulmonary stenosis, not the VSD. The murmur gets quieter during a spell, because less blood crosses the narrowed outflow.
• Older unrepaired children squat after exertion. Squatting raises systemic resistance, forcing more blood through the lungs.
• Clubbing in older unrepaired children.

Hypercyanotic ("tet") spells: Sudden worsening of cyanosis, often triggered by crying, feeding or dehydration. The RV outflow goes into spasm, so more blood shunts right-to-left. Spells can cause collapse, seizures or death. Management:

• Calm the child.
• Knee–chest position (raises systemic resistance).
• Oxygen.
• IV or intranasal opioid (morphine).
• IV fluid bolus.
• IV propranolol to relax the outflow muscle.
• Phenylephrine to raise systemic resistance.
• Emergency surgery if refractory.

Investigations:

• Chest X-ray: Boot-shaped heart (upturned apex from RVH, concave pulmonary bay) and reduced lung markings.
• ECG: RVH and right axis deviation.
• Echo: Diagnostic.

Management:

• Complete surgical repair at about 3–6 months: close the VSD and relieve the RV outflow obstruction, often with a patch across the pulmonary valve ring.
• A temporary Blalock–Taussig shunt (subclavian to pulmonary artery) or an RV outflow stent in very cyanosed young babies.

Adults with repaired tetralogy:

• Pulmonary regurgitation (from the patch) gradually dilates the RV. Pulmonary valve replacement (surgical or transcatheter) is timed by RV size on cardiac MRI and by symptoms.
• Arrhythmias: Atrial arrhythmias, VT and sudden death. A QRS of 180 ms or more is a risk marker.
• RBBB is almost universal after repair.

💡 MRCP Pearl: A cyanotic child who squats after exercise = tetralogy of Fallot. In repaired adults, think pulmonary regurgitation, RV dilatation and VT.

↑ Back to index

Transposition of the Great Arteries

Mechanism: The great arteries are switched: the aorta arises from the RV and the pulmonary artery from the LV. This creates two parallel circulations instead of one in series. Deoxygenated blood goes round the body and back; oxygenated blood goes round the lungs and back. The baby survives only if blood can mix through the foramen ovale, ductus arteriosus or a VSD.

Associations: Maternal diabetes; more common in boys.

Clinical pattern:

• Profound cyanosis on the first day, worsening as the duct closes, in a baby who is otherwise well-grown.
• Often no murmur.
• Little response to oxygen.

Investigations:

• Chest X-ray: "Egg on a string" - a narrow mediastinum because the great arteries lie one in front of the other.
• Echo: Diagnostic.

Emergency management:

• Prostaglandin infusion to keep the duct open.
• Balloon atrial septostomy (Rashkind) if mixing is poor. A balloon catheter is pulled across the foramen ovale to tear a larger hole, often done at the bedside under echo guidance.

Definitive management: Arterial switch operation in the first 2–3 weeks of life. The aorta and pulmonary artery are swapped back, and the coronary arteries are moved to the new aorta. Long-term problems include neo-aortic dilatation, coronary narrowing and pulmonary artery stenosis.

Older adults: Many had an atrial switch (Mustard or Senning) before the 1990s. Blood was redirected at atrial level, leaving the RV pumping to the body. In later life this causes:

• Systemic RV failure.
• Tricuspid regurgitation.
• Atrial arrhythmias.
• Sinus node dysfunction.
• Baffle obstruction or leaks.

💡 Clinical Pearl: A big, well-looking newborn who is deeply blue on day one with no murmur is likely to have TGA. Start prostaglandin and call cardiology.

↑ Back to index

Congenitally Corrected Transposition

Mechanism: Both the ventricles and the great arteries are switched. Blood follows this path:

• Right atrium → morphological LV → pulmonary artery.
• Left atrium → morphological RV → aorta.

The circulation is therefore physiologically "corrected" and the patient is not cyanosed. However, the RV and its tricuspid valve must pump to the body for life.

Clinical pattern: Often diagnosed in adulthood, with:

• Complete heart block (a displaced, fragile AV node; about 2% per year).
• Systemic AV (tricuspid) valve regurgitation.
• Systemic RV failure.
• Associated VSD or pulmonary stenosis.

Management: Specialist ACHD follow-up; pacing for heart block; heart failure therapy; valve surgery for significant regurgitation.

↑ Back to index

Tricuspid Atresia and Single Ventricle

Mechanism: In tricuspid atresia there is no tricuspid valve and the RV is small and non-functional. Blood must cross an ASD to the left heart and reach the lungs through a VSD or the duct. Tricuspid atresia is one of several "single ventricle" hearts, in which only one ventricle is big enough to pump.

Clinical pattern: Cyanosis in the newborn. The ECG shows left axis deviation and LVH - unusual for a cyanotic lesion.

Staged management towards a Fontan circulation: Because there is only one usable ventricle, the aim is to route systemic venous blood directly to the lungs, bypassing the heart, and use the single ventricle to pump to the body.