Chapter 21 · CHD in Infants/Children · Arrhythmias · Acquired Heart Disease

Infant & child with CHD (heart failure, pulmonary hypertension, Eisenmenger) · Cardiac arrhythmias (SVT, atrial flutter, VT, heart block, LQTS) · Acquired disorders (Kawasaki disease, rheumatic heart disease, cardiomyopathy, myocarditis, pulmonary hypertension)
📌 Core principles: CHD in older children: VSD, TOF repair, coarctation; monitor for heart failure, arrhythmias, pulmonary hypertension. Arrhythmias: SVT (adenosine), VT (amiodarone, ICD), heart block (pacing). Acquired: Kawasaki disease (IVIG, coronary aneurysms), acute rheumatic fever (Jones criteria, penicillin), dilated cardiomyopathy (ACEi, carvedilol), myocarditis (supportive, IVIG controversial), pulmonary hypertension (targeted vasodilators).

📖 CHD in Children, Arrhythmias & Acquired Disease

🫀 Infant/child with CHD
Heart failure: large VSD, AVSD, truncus arteriosus (presents 4-8 weeks). Pulmonary hypertension (PAH) may develop with large left-to-right shunts; if irreversible → Eisenmenger syndrome. Long-term: arrhythmias (post-repair), endocarditis risk, exercise limitation.
⚡ Cardiac arrhythmias
SVT (most common in infants): narrow QRS, rate 220-300, terminate with adenosine. Atrial flutter (sawtooth). VT (wide QRS, unstable). Heart block (complete – maternal lupus). Long QT syndrome (syncope, sudden death; beta-blockers, ICD).
🦠 Acquired cardiovascular disorders
Kawasaki disease: leading cause of acquired heart disease in children (coronary aneurysms); IVIG within 10 days. Acute rheumatic fever (ARF): Jones criteria (carditis, arthritis, chorea); secondary prevention with penicillin. Myocarditis (viral: enterovirus, parvovirus). Dilated cardiomyopathy (DCM) – systolic dysfunction; treat with ACEi, carvedilol, diuretics. Hypertrophic cardiomyopathy (HCM) – sarcomeric mutations, risk of sudden death.
🩸 Pulmonary hypertension
Idiopathic PAH, heritable (BMPR2), associated (CHD, connective tissue disease). Diagnosis: right heart catheterisation. Treatment: sildenafil, bosentan, prostacyclin analogues, lung transplant.

🔎 Symptom-based approach: infant with CHD, palpitations, fever with rash

1️⃣
3-month-old with tachypnoea, poor feeding, hepatomegaly, pansystolic murmur.
Heart failure due to large VSD. Diuretics, ACE inhibitor, surgical closure.
2️⃣
Infant with episodic pallor, heart rate 280 bpm, well between episodes.
Supraventricular tachycardia (SVT). Vagal manoeuvres, IV adenosine; long-term propranolol.
3️⃣
5-year-old with fever, conjunctivitis, rash, cervical lymphadenopathy for 5 days.
Kawasaki disease (incomplete Kawasaki possible). IVIG 2 g/kg, high-dose aspirin.
4️⃣
10-year-old with migratory polyarthritis, chorea, and elevated ASOT.
Acute rheumatic fever. Benzathine penicillin prophylaxis.
5️⃣
Adolescent with syncope during exercise, family history of sudden death. ECG shows LVH, deep Q waves.
Hypertrophic cardiomyopathy (HCM). Beta-blocker, ICD evaluation.
⚠️ Red flags for arrhythmia: Syncope, palpitations with dizziness, family history of sudden death, prolonged QT, Brugada pattern.

📋 Management algorithms: Arrhythmias, Kawasaki, ARF, PAH

⚡
Supraventricular tachycardia (SVT) – acute & chronic
▪️ Acute: vagal manoeuvres (ice to face, Valsalva); IV adenosine (0.1 mg/kg rapid push; may increase to 0.2 mg/kg).
▪️ Haemodynamically unstable: synchronized cardioversion (0.5-1 J/kg).
▪️ Chronic: propranolol (1-2 mg/kg/day), digoxin, flecainide, or catheter ablation.
🦠
Kawasaki disease – management
▪️ IVIG 2 g/kg within 10 days of fever onset.
▪️ High-dose aspirin 80-100 mg/kg/day until afebrile → low-dose 3-5 mg/kg/day.
▪️ Echocardiogram at diagnosis, 2 weeks, 6 weeks. If coronary aneurysms, long-term aspirin, warfarin if giant aneurysms.
▪️ IVIG-resistant: second dose, infliximab, or steroids.
🩺
Acute rheumatic fever – treatment & secondary prevention
▪️ Treat acute infection: penicillin (or erythromycin if allergic).
▪️ Anti-inflammatory: aspirin (arthritis) / prednisolone (severe carditis).
▪️ Bed rest for carditis.
▪️ Secondary prophylaxis: benzathine penicillin G every 3-4 weeks (at least 5 years or until age 21).
🩸
Pulmonary arterial hypertension (PAH) – therapy
▪️ Supportive: oxygen, diuretics (RV failure), warfarin (if central line).
▪️ Vasodilators: sildenafil (PDE5i), bosentan (ERA).
▪️ Advanced: IV prostacyclin (epoprostenol), subcutaneous treprostinil.
▪️ Atrial septostomy, lung transplantation.

💡 Reflex prompts – CHD in children, arrhythmias, acquired disease

🫀 An infant with large VSD and heart failure. When does heart failure typically present?
4-8 weeks of life (as pulmonary vascular resistance falls).
⚡ First-line acute treatment for stable SVT in an infant.
IV adenosine (0.1 mg/kg rapid push).
🦠 A child with prolonged fever, conjunctivitis, rash, and cervical lymphadenopathy for 5 days. Diagnosis?
Kawasaki disease. IVIG within 10 days reduces coronary aneurysms.
💊 A 10-year-old with acute rheumatic fever and carditis. Secondary prophylaxis?
Benzathine penicillin G 1.2 million units IM every 3-4 weeks.
📊 A 15-year-old with syncope during exercise, family history of sudden death. Likely cardiomyopathy?
Hypertrophic cardiomyopathy (HCM). Beta-blockers, ICD.
🩺 A child with dilated cardiomyopathy, LVEF 25%. Guideline medical therapy?
Enalapril + carvedilol + spironolactone + furosemide.
❤️ Most common arrhythmia in infants.
Supraventricular tachycardia (SVT).
🩸 A child with unrepaired VSD and Eisenmenger syndrome. Management?
Pulmonary vasodilators (bosentan, sildenafil), avoid pregnancy, consider transplant.
⚡ ECG finding in Wolff-Parkinson-White (WPW) syndrome.
Delta wave, short PR interval, wide QRS.
🦠 A child with myocarditis after viral illness. Mainstay of treatment?
Supportive care (milrinone, diuretics, ECMO if severe). IVIG controversial.