Chapter 21 · Congenital Heart Disease (Fetal Diagnosis & Neonate)

Fetal diagnosis of heart disease · The neonate with congenital heart disease · Duct-dependent lesions · Critical CHD presentation · Initial stabilisation · Prostaglandin E1 · Hyperoxia test · Balloon atrial septostomy
📌 Core principles: Fetal echocardiography from 16-20 weeks for high-risk cases (family history, maternal diabetes, abnormal nuchal translucency). Neonatal CHD presents with cyanosis, heart failure, shock, or murmur. Duct-dependent lesions: pulmonary (cyanosis) → PGE1; systemic (shock) → PGE1. Hyperoxia test helps differentiate cardiac from respiratory cyanosis. Balloon atrial septostomy (Rashkind) for transposition of great arteries (TGA) improves mixing. Emergency surgery for critical lesions (TGA, HLHS).

📖 Congenital Heart Disease – Fetal & Neonate

👶 Fetal diagnosis of heart disease
Fetal echocardiography (18-22 weeks). Indications: family history of CHD, maternal diabetes, abnormal nuchal translucency, extracardiac anomalies, monochorionic twins. Detection of critical lesions (HLHS, TGA, TOF). Allows parental counselling, planning of delivery at tertiary centre, in-utero interventions (rare).
💙 Neonate with CHD – presentation
▪️ Cyanosis (duct-dependent pulmonary circulation: TGA, TOF, pulmonary atresia, tricuspid atresia).
▪️ Shock / collapse (duct-dependent systemic circulation: HLHS, critical aortic stenosis, coarctation, interrupted aortic arch).
▪️ Heart failure (large VSD, AV canal, truncus arteriosus – presents at 4-8 weeks).
▪️ Isolated murmur (small VSD, mild PS, ASD – asymptomatic).
🩺 Clinical evaluation & investigations
Hyperoxia test: PaO2 <50 mmHg after 100% O2 suggests cyanotic CHD. CXR: cardiomegaly, pulmonary vascularity. ECG: axis, ventricular hypertrophy. Echocardiography: gold standard. Blood gas, lactate, pre/postductal saturations.
💊 Emergency management (duct-dependent)
Start PGE1 (alprostadil) 0.005-0.05 mcg/kg/min IV to maintain ductal patency. Side effects: apnoea, fever, hypotension, bradycardia. If TGA: balloon atrial septostomy (Rashkind) improves mixing. Treat metabolic acidosis, correct hypoglycaemia, consider ventilation.
🔬 Specific neonatal CHD
TGA: most common cyanotic CHD in neonate, hyperoxia test fails, ‘egg on side’ CXR, Rashkind procedure, arterial switch operation. TOF: cyanotic spells (hypercyanotic episodes). HLHS: duct-dependent systemic circulation, presents with shock when PDA closes. Coarctation: weak femoral pulses, upper limb hypertension.

🔎 Symptom-based approach: cyanosis, shock, murmur in neonate

1️⃣
Neonate with central cyanosis, normal CXR, hyperoxia test fails (PaO2 <50 mmHg after 100% O2).
Likely cyanotic CHD (TGA most common). Start PGE1, echocardiogram, balloon atrial septostomy.
2️⃣
Neonate with shock, metabolic acidosis, absent femoral pulses.
Duct-dependent systemic circulation (HLHS, coarctation, interrupted aortic arch). Start PGE1, treat acidosis, inotropes, echo.
3️⃣
Newborn with murmur, no cyanosis, normal pulses, well infant.
Small VSD, ASD, mild PS. Monitor, echo if persistent or symptomatic.
4️⃣
Neonate with cyanosis that worsens with crying, improves with squatting position (older infant).
Tetralogy of Fallot (hypercyanotic spells).
5️⃣
Prenatal diagnosis: 20-week fetus with HLHS. Plan?
Delivery at tertiary centre, immediate PGE1 after birth, neonatal palliation (Norwood procedure) or transplant counselling.
⚠️ Hyperoxia test: Place infant on 100% O2 for 10 min. PaO2 >150 mmHg – likely respiratory; <50 mmHg – likely cyanotic CHD (TGA, TOF, tricuspid atresia).

📋 Management algorithms: Neonate with suspected CHD

🩺
Evaluation of cyanotic neonate
▪️ Obtain preductal (right arm) and postductal (lower limb) SpO2. Differential cyanosis (lower limb lower) suggests PDA with pulmonary hypertension (e.g., PPHN, coarctation).
▪️ Hyperoxia test: draw right radial artery blood gas on 100% FiO2.
▪️ Chest X-ray (cardiomegaly, pulmonary vascularity).
▪️ ECG (axis, chamber enlargement).
▪️ Urgent echocardiography (structure, function, ductal flow).
💊
Initial stabilisation of duct-dependent CHD
▪️ Start prostaglandin E1 (alprostadil) IV infusion: 0.005-0.05 mcg/kg/min (titrate to effect).
▪️ Secure airway if apnoea (intubate if necessary).
▪️ Correct metabolic acidosis (IV fluids, bicarbonate if pH <7.1).
▪️ Treat hypoglycaemia (10% dextrose).
▪️ Inotropes if shock (dopamine/dobutamine).
🪡
Specific interventions
▪️ TGA: balloon atrial septostomy (Rashkind) usually in catheter lab.
▪️ Critical pulmonary stenosis / aortic stenosis: balloon valvuloplasty.
▪️ Coarctation: PGE1 stabilisation, then surgical repair.
▪️ HLHS: Norwood/Sano procedure or hybrid approach.

💡 Reflex prompts – Fetal CHD & Neonatal CHD

👶 A 20-week fetus with increased nuchal translucency. Next step?
Fetal echocardiography to exclude structural CHD.
💙 A neonate with central cyanosis, CXR shows ‘egg on side’. Diagnosis?
Transposition of great arteries (TGA).
🩺 A neonate with shock, absent femoral pulses, and metabolic acidosis after PDA closure. Likely lesion?
Duct-dependent systemic circulation (HLHS, coarctation).
💊 First-line drug to maintain ductal patency in duct-dependent CHD.
Prostaglandin E1 (alprostadil).
🩸 Hyperoxia test: PaO2 40 mmHg on 100% FiO2. Interpretation?
Cyanotic CHD (TGA, TOF, pulmonary atresia).
🪡 Intervention for TGA neonate before arterial switch.
Balloon atrial septostomy (Rashkind) – creates mixing at atrial level.
🩺 A 1-week-old with cyanosis and a harsh systolic murmur, CXR shows boot-shaped heart, oligaemic lungs. Diagnosis?
Tetralogy of Fallot (TOF).
❤️ A neonate with heart failure at 1 week – think of:
Arteriovenous malformation, anomalous coronary artery, critical aortic stenosis.
📊 A newborn with right arm SpO2 95%, leg SpO2 70%. Differential cyanosis indicates?
PDA with pulmonary hypertension (or coarctation with right-to-left ductal shunt).
👶 Most common CHD diagnosed prenatally?
Hypoplastic left heart syndrome (HLHS) – due to four-chamber view asymmetry.