Paediatric Heart Failure

Paediatric heart failure is a clinical syndrome in which the heart cannot meet the metabolic demands of the body or can do so only at elevated filling pressures. Causes and presentations differ from adults, with congenital heart disease predominating. Incidence is about 0.9-7.4 per 100,000 children yearly, and about 11,000-14,000 hospitalisations annually in the United States.

Aetiology by age

• Fetus: supraventricular tachycardia (hydrops), complete heart block, anaemia, twin-twin transfusion, severe valvular regurgitation.
• Neonate (first week): left heart obstruction (hypoplastic left heart, critical aortic stenosis, coarctation, interrupted aortic arch), perinatal asphyxia (myocardial dysfunction), severe anaemia, sepsis, arrhythmias (SVT), systemic AV malformation (vein of Galen), transient myocardial dysfunction in infants of diabetic mothers.
• Infants (1-6 months): large left-to-right shunts (ventricular septal defect, patent ductus arteriosus, AV canal) as pulmonary vascular resistance falls (peak at 6-8 weeks), anomalous left coronary artery from pulmonary artery (ALCAPA), cardiomyopathy, myocarditis, and arrhythmias.
• Older children: dilated cardiomyopathy (idiopathic, genetic, post-myocarditis), myocarditis (viral: coxsackie B, adenovirus, parvovirus B19, SARS-CoV-2 and MIS-C), rheumatic heart disease, endocarditis, anthracycline cardiotoxicity (cumulative dose over 250-300 mg/m2), hypertrophic and restrictive cardiomyopathy, arrhythmia-induced (tachycardia, complete heart block), Duchenne muscular dystrophy cardiomyopathy, Kawasaki disease sequelae, Eisenmenger syndrome, pulmonary hypertension, thalassaemia (iron overload), systemic lupus, and failing Fontan circulation and repaired congenital heart disease.
• Others: metabolic and mitochondrial disorders (carnitine deficiency, Pompe disease, Barth syndrome), thyrotoxicosis, severe anaemia, nephritis/hypertension, and cystic fibrosis (cor pulmonale).
• Classification: Ross classification (infants), modified NYHA (older), and ACC/AHA stages A-D adapted for children. Types: systolic (reduced ejection fraction), diastolic, high-output (anaemia, AV malformation, thyrotoxicosis), right heart failure (pulmonary hypertension, Fontan), and single ventricle failure.
• Pathophysiology: volume or pressure overload and myocardial dysfunction trigger neurohormonal activation (sympathetic, renin-angiotensin-aldosterone, natriuretic peptides, endothelin) with adverse remodelling. Children have lower myocardial reserve and immature calcium handling.
• Prognosis: depends on cause. Dilated cardiomyopathy in children has 5-year transplant-free survival around 50-60%. Myocarditis recovers in about half, many need MCS or transplant.

Infants

• Poor feeding (tiring, sweating during feeds), tachypnoea, tachycardia, failure to thrive, irritability, diaphoresis, recurrent chest infections, hepatomegaly, cool extremities, cyanosis (if shunt), weak pulses (in left heart obstruction), gallop rhythm, murmurs (VSD pansystolic, PDA continuous), and cardiomegaly. Oedema and raised JVP are late and uncommon.
• Shock with duct closure: grey, collapsed, acidotic, absent femoral pulses (coarctation, HLHS).

Older children

• Fatigue, exercise intolerance, dyspnoea, orthopnoea, cough, abdominal pain, nausea and vomiting (hepatic congestion), anorexia, oedema (periorbital, peripheral), weight gain, syncope, palpitations, and chest pain.
• Signs: tachycardia, tachypnoea, gallop rhythm, hepatomegaly, raised JVP, basal crackles, cool extremities, narrow pulse pressure, murmurs (mitral regurgitation).
• Syndrome-specific clues: myocarditis (preceding viral illness, fever, chest pain, arrhythmia, sudden onset), anthracycline exposure, family history of cardiomyopathy or sudden death, dysmorphism, neuromuscular disease, and Kawasaki disease history.
• Red flags: shock, arrhythmia, syncope, severe hypoxaemia, poor perfusion, and altered consciousness.
• Differential diagnosis: bronchiolitis and pneumonia (tachypnoea with wheeze), sepsis, severe anaemia, metabolic disease, congenital lung disease, and renal disease.

Initial tests

• Chest radiograph (cardiomegaly with cardiothoracic ratio above 0.6 in infants, pulmonary congestion), ECG (arrhythmia, hypertrophy, ST-T changes, low voltages, Q waves in ALCAPA), echocardiography (the key investigation: structure, ventricular systolic/diastolic function, ejection fraction or fractional shortening, valve regurgitation, pericardial effusion, coronary origins, pulmonary pressures).
• Biomarkers: BNP (above 100 pg/mL) or NT-proBNP (age-dependent thresholds, above 450 pg/mL in infants), troponin (myocarditis), CBC, electrolytes, renal and liver function, lactate, glucose, calcium, thyroid function, iron studies, CRP, blood cultures.
• Cardiac MRI: myocarditis (Lake Louise criteria), cardiomyopathy phenotype, fibrosis (late gadolinium enhancement), volumes.
• Cardiac catheterisation: haemodynamics, endomyocardial biopsy (myocarditis, infiltrative disease), coronary angiography, and pulmonary vascular resistance for transplant.
• Genetic and metabolic testing: cardiomyopathy gene panels (sarcomeric, TTN, LMNA, desmosomal), mitochondrial studies, plasma acylcarnitines, urine organic acids, carnitine, enzyme assays (Pompe), and neuromuscular evaluation (CK).
• Infection studies: viral PCR (blood, nasopharyngeal, myocardial tissue), serology, SARS-CoV-2.
• Holter monitor/event recorder, exercise testing (older children, VO2 max), and 6-minute walk.
• Screening in at-risk groups: anthracycline survivors (echocardiography per Children's Oncology Group schedules), Duchenne (cardiac MRI from age 10), and relatives of cardiomyopathy.

Acute decompensated heart failure

• Stabilise: oxygen if hypoxic, positioning, minimal handling, fluid restriction (110-120 mL/kg/day for infants where feasible), nasogastric feeding (high-calorie), correction of anaemia, acidosis, hypoglycaemia, and electrolytes.
• Diuretics: furosemide 0.5-2 mg/kg IV every 6-12 hours (or infusion 0.05-0.5 mg/kg/h), with spironolactone 1-3 mg/kg/day, chlorothiazide 10-20 mg/kg/day, and metolazone as adjunct. Monitor potassium and creatinine.
• Inotropes in low output state: dobutamine 2.5-10 micrograms/kg/min, dopamine 3-10 micrograms/kg/min, epinephrine 0.02-0.1 micrograms/kg/min, milrinone 0.25-0.75 micrograms/kg/min (with loading 25-50 micrograms/kg, watch hypotension) which is favoured when vascular resistance is high. Vasodilators (nitroprusside 0.5-3 micrograms/kg/min, nitroglycerin) if blood pressure permits.
• Ventilatory support (noninvasive or intubation) avoiding high positive pressure in right heart failure. Treat arrhythmias (cardioversion for unstable SVT, adenosine 0.1 mg/kg rapid IV, amiodarone 5 mg/kg over 30-60 minutes).
• Early use of mechanical support (ECMO, Berlin Heart EXCOR, Impella in larger children) for refractory shock.

Chronic therapy (systolic dysfunction; evidence mostly extrapolated from adults)

• ACE inhibitors: enalapril 0.1 mg/kg/day increasing to 0.5 mg/kg/day divided twice daily, captopril 0.3-2.5 mg/kg/day divided three times daily (infants 0.1-0.5 mg/kg), lisinopril 0.1-0.4 mg/kg once daily. Monitor potassium, creatinine, hypotension, cough. Avoid in pregnancy.
• Beta blockers: carvedilol 0.05 mg/kg twice daily increasing every 2 weeks to 0.4-0.5 mg/kg twice daily (maximum 25 mg twice daily), metoprolol succinate 0.5-2 mg/kg/day, bisoprolol. Start when euvolaemic and stable.
• Mineralocorticoid antagonists: spironolactone 1-3 mg/kg/day, eplerenone.
• Angiotensin receptor blockers: losartan 0.7-1.4 mg/kg/day (maximum 100 mg) or valsartan when ACE inhibitor not tolerated.
• Sacubitril/valsartan (approved from age 1 year): starting 1.6 mg/kg twice daily (target 3.1 mg/kg twice daily), in children with systemic left ventricular systolic dysfunction (PANORAMA-HF).
• SGLT2 inhibitors (dapagliflozin 5-10 mg daily, empagliflozin) emerging in older children with cardiomyopathy and diabetic/renal disease.
• Ivabradine 0.05 mg/kg twice daily up to 0.2 mg/kg twice daily (heart rate reduction in dilated cardiomyopathy, approved from 6 months in sinus rhythm).
• Digoxin 5-10 micrograms/kg/day (adjunct for symptomatic relief, monitor levels 0.5-1.0 ng/mL, interactions).
• Anticoagulation: aspirin 3-5 mg/kg/day, warfarin (INR 2-3) or enoxaparin for dilated cardiomyopathy with severe dysfunction (ejection fraction below 25-30%), intracardiac thrombus, atrial fibrillation, or Fontan circulation.
• Nutrition: high-calorie formulas (24-30 kcal/oz), fortification, enteral feeding by tube, treatment of reflux, iron and vitamin D supplementation, salt restriction (modest) in older children.
• Immunisation: all routine vaccines, annual influenza, pneumococcal, and RSV prophylaxis (nirsevimab) in infants with haemodynamically significant disease.
• Endocarditis prophylaxis only for specified high-risk lesions.
• Exercise: encouraged within limits, avoid competitive sports in cardiomyopathy.

Cause-specific treatment

• Congenital heart disease with shunts: diuretics, ACE inhibitor, nutrition, and early surgical or catheter closure (VSD at 3-6 months if refractory failure to thrive, PDA closure by indomethacin 0.2 mg/kg or ibuprofen 10 mg/kg, paracetamol, or device/surgery).
• Neonatal left heart obstruction: prostaglandin E1 (0.01-0.05 micrograms/kg/min), avoid oxygen excess, inotropes, and urgent surgery/Norwood.
• ALCAPA: surgical re-implantation of the left coronary artery.
• Myocarditis: supportive care, heart failure therapy, arrhythmia management, early MCS, IVIG 2 g/kg (evidence limited), steroids in selected cases (giant cell, eosinophilic, autoimmune), and avoid NSAIDs and exercise for 3-6 months.
• Arrhythmia-induced: rate/rhythm control, ablation, pacemaker for complete heart block.
• Anthracycline cardiotoxicity: ACE inhibitor, beta blocker, dexrazoxane for prevention.
• Metabolic: carnitine 50-100 mg/kg/day, enzyme replacement (alglucosidase alfa 20 mg/kg every 2 weeks for Pompe), treat thyrotoxicosis, correct anaemia and iron overload (chelation).
• Duchenne: ACE inhibitor from age 10, mineralocorticoid antagonists, beta blocker.
• Rheumatic heart disease: benzathine penicillin G prophylaxis (1.2 million units every 3-4 weeks), valve surgery.
• Single ventricle/Fontan failure: diuretics, afterload reduction, pulmonary vasodilators (sildenafil), treat protein-losing enteropathy, transplant.

Advanced therapies

• Mechanical support: ECMO, Berlin Heart EXCOR (the paediatric ventricular assist device, bridging infants), HeartMate 3 or HeartWare in adolescents.
• Heart transplantation: for refractory failure, 1-year survival about 90%, 10-year about 60%, with risks of rejection, infection, coronary allograft vasculopathy, and lymphoproliferative disease. Immunosuppression: tacrolimus (trough 8-12 ng/mL early), mycophenolate, steroids, basiliximab induction.

Follow-up

Frequent review (weekly to monthly initially) with growth, symptoms, medication adjustment, echo, BNP. Cardiology and heart failure clinic, nutritional support, developmental surveillance, school liaison, psychological support, transition to adult services, and family genetic counselling and screening (first-degree relatives with ECG and echo).