15.1 Pediatric Cardiac and Congenital Heart Disorders
Key Takeaways
- Acyanotic defects shunt blood left to right and produce pulmonary overcirculation and heart failure, while cyanotic defects shunt right to left and produce hypoxaemia that does not correct with supplemental oxygen.
- The first sign of heart failure in an infant is usually feeding difficulty with diaphoresis and tachypnoea during feeds, followed by poor weight gain, not peripheral oedema.
- During a hypercyanotic tet spell, place the infant in the knee-chest position, give oxygen, calm the child, and administer prescribed morphine and fluids to increase systemic vascular resistance and pulmonary blood flow.
- Intravenous immunoglobulin is the primary treatment for Kawasaki disease and must be given within the first ten days to reduce coronary artery aneurysm risk; live vaccines are deferred for eleven months afterwards.
- Check the apical pulse for a full minute before every dose of digoxin in a child and withhold the dose for a rate below 90 to 110 beats per minute in an infant or below 70 in an older child, per the prescribed parameters.
15.1 Pediatric Cardiac and Congenital Heart Disorders
Congenital heart disease affects roughly 8 to 10 per 1,000 live births worldwide, and consanguinity patterns in parts of the Gulf make it a familiar presentation in Qatari paediatric practice. The exam logic is simple once you fix the direction of the shunt: left-to-right means too much blood in the lungs and heart failure; right-to-left means deoxygenated blood in the systemic circulation and cyanosis.
Classifying the Defects
| Defect | Type | Shunt | Hallmark |
|---|---|---|---|
| Ventricular septal defect (VSD) | Acyanotic | L → R | Loud harsh holosystolic murmur; many close spontaneously |
| Atrial septal defect (ASD) | Acyanotic | L → R | Fixed split second heart sound; often asymptomatic in childhood |
| Patent ductus arteriosus (PDA) | Acyanotic | L → R | Continuous machinery murmur; bounding pulses, wide pulse pressure |
| Coarctation of the aorta | Acyanotic (obstructive) | — | Upper limb hypertension with weak or absent femoral pulses; blood pressure differential arm to leg |
| Pulmonary stenosis | Acyanotic (obstructive) | — | Systolic ejection murmur; right ventricular hypertrophy |
| Tetralogy of Fallot | Cyanotic | R → L | Four components: VSD, pulmonary stenosis, overriding aorta, right ventricular hypertrophy; hypercyanotic spells |
| Transposition of the great arteries | Cyanotic | Parallel circulations | Cyanosis within hours of birth; survival depends on mixing — prostaglandin E1 keeps the duct open |
| Tricuspid atresia | Cyanotic | R → L | Cyanosis, requires shunt or staged palliation |
| Truncus arteriosus | Cyanotic (mixed) | Mixed | Single vessel, early heart failure and cyanosis |
A useful discriminator: cyanosis that does not improve with supplemental oxygen points to a right-to-left shunt rather than lung pathology, because the blood bypasses the lungs entirely.
Coarctation deserves a specific nursing habit — assess both upper and lower limb pulses and blood pressures in any infant with a murmur or unexplained hypertension. A blood pressure higher in the arms than the legs with diminished femoral pulses is the finding that makes the diagnosis at the bedside.
Heart Failure in Infants
Infants do not present the way adults do. They do not report orthopnoea, and peripheral oedema is a late and unreliable sign. The first and most sensitive indicator is feeding.
| System | Infant findings |
|---|---|
| Feeding | Tires quickly, takes > 30 minutes per feed, diaphoresis on the forehead while feeding, poor weight gain |
| Respiratory | Tachypnoea, retractions, nasal flaring, grunting, frequent respiratory infections, wheeze |
| Cardiac | Tachycardia, gallop rhythm, weak peripheral pulses, prolonged capillary refill |
| Systemic | Hepatomegaly (the paediatric equivalent of adult peripheral oedema), periorbital oedema, irritability |
Nursing management: cluster care to allow uninterrupted rest; feed small volumes more frequently, use a soft or enlarged-hole teat to reduce the work of sucking, limit a feed to about 30 minutes and supplement by nasogastric tube if the infant tires; position with the head elevated; maintain a neutral thermal environment because both cold and heat increase oxygen demand; measure daily weight at the same time on the same scale as the most sensitive fluid-status indicator; monitor strict intake and output; and prevent infection rigorously, since a respiratory infection can decompensate a marginally compensated infant.
The Hypercyanotic ("Tet") Spell
In tetralogy of Fallot, crying, feeding, defecation, or waking can precipitate an acute fall in systemic vascular resistance or a rise in infundibular spasm, increasing the right-to-left shunt. The infant becomes acutely and deeply cyanotic, hyperpnoeic, irritable and then limp, and the murmur paradoxically softens because less blood is crossing the pulmonary outflow tract.
Emergency sequence:
- Place the infant in the knee-chest position (an older child will squat instinctively). This kinks the femoral arteries, raising systemic vascular resistance and forcing more blood through the pulmonary circulation.
- Administer 100% oxygen.
- Calm the infant — a soothing voice, minimal handling, and holding by the parent. Agitation worsens the spell, which is why aggressive procedures are counterproductive.
- Administer prescribed morphine (reduces hyperpnoea and infundibular spasm) and an intravenous fluid bolus (increases preload).
- Escalate; a prescribed beta-blocker or phenylephrine may follow.
Digoxin Safety in Children
Digoxin remains commonly prescribed for paediatric heart failure and has a narrow therapeutic index.
- Count the apical pulse for a full minute before every dose. Withhold and report for a rate below the prescribed parameter — conventionally about 90 to 110 bpm in an infant, 70 bpm in an older child, and 60 bpm in an adolescent or adult.
- Give at consistent times, one hour before or two hours after feeds.
- Do not repeat a dose if the child vomits, and do not give a double dose for a missed one.
- Signs of toxicity in a child are predominantly gastrointestinal and cardiac: vomiting, anorexia, nausea, bradycardia, and arrhythmia. The visual disturbances classically described in adults are rarely reported by young children.
- Hypokalaemia potentiates toxicity, so monitor potassium, especially where a diuretic is co-prescribed.
- Teach parents to keep it in a locked place and never to describe it as sweets.
Acquired Paediatric Cardiac Disease
Kawasaki disease
An acute vasculitis of young children, and the leading cause of acquired heart disease in children in developed countries. Diagnosis is clinical: fever persisting five days or more, plus conjunctival injection without exudate, oral changes (strawberry tongue, cracked red lips), a polymorphous rash, cervical lymphadenopathy, and extremity changes (erythema and oedema of the hands and feet, followed by periungual desquamation in the subacute phase).
The stake is the coronary arteries. Untreated, around a quarter of children develop coronary aneurysms. Intravenous immunoglobulin given within the first 10 days, with aspirin, markedly reduces that risk. Nursing care includes cardiac monitoring during the immunoglobulin infusion, meticulous comfort measures for an intensely irritable child (cool cloths, soft foods, lip lubrication, quiet environment, parental presence), and teaching two points that are frequently examined: aspirin is continued as prescribed despite the general paediatric Reye syndrome caution, and live vaccines such as MMR and varicella must be deferred for about 11 months after intravenous immunoglobulin because passive antibody blunts the vaccine response.
Acute rheumatic fever
An immune sequel of untreated group A streptococcal pharyngitis, diagnosed using the Jones criteria: major manifestations include carditis, polyarthritis, Sydenham chorea, erythema marginatum, and subcutaneous nodules. The most serious long-term consequence is rheumatic heart disease, particularly mitral valve damage. Prevention is the nursing message: complete the full course of antibiotics for streptococcal pharyngitis even after the sore throat resolves. Established rheumatic fever requires long-term secondary prophylaxis with regular penicillin for years.
Infective endocarditis prophylaxis
Current guidance reserves antibiotic prophylaxis for the highest-risk cardiac lesions — prosthetic valves or prosthetic repair material, previous endocarditis, and certain unrepaired or recently repaired cyanotic congenital defects — before specified dental and selected invasive procedures. For all children with structural heart disease, daily oral hygiene and regular dental review are more protective than intermittent antibiotics, and that is the teaching point examiners look for.
A 6-month-old with tetralogy of Fallot becomes acutely and deeply cyanotic, hyperpnoeic, and irritable after a prolonged crying episode, and the previously loud murmur is now much softer. What is the nurse's immediate priority action?
A nurse is preparing to administer digoxin to a 4-month-old infant with heart failure. The apical pulse counted over one full minute is 88 beats per minute, and the infant vomited the previous dose 20 minutes after administration. What should the nurse do?
A 3-year-old who received intravenous immunoglobulin for Kawasaki disease six weeks ago is brought to a health centre for routine immunisations, which include MMR and varicella. What is the most appropriate nursing action?