Pediatric Cardiology
Cardiology items test your ability to triage a murmur, distinguish cyanotic from acyanotic congenital disease, recognise duct-dependent circulation, and manage the two acquired conditions that dominate the region: acute rheumatic fever and Kawasaki disease.
Murmur triage
- Innocent murmurs are soft, systolic, without a thrill, with a normal second heart sound, and vary with posture; the child is asymptomatic and thriving.
- Ventricular septal defect: harsh pansystolic murmur at the left lower sternal edge.
- Atrial septal defect: fixed, widely split second heart sound with an ejection systolic murmur.
- Patent ductus arteriosus: continuous machinery murmur with bounding pulses.
- Tetralogy of Fallot: ejection systolic murmur, cyanosis, squatting, boot-shaped heart on radiograph.
Cyanosis and duct dependence
- Hyperoxia test: a PaO2 above 150 mmHg on 100% oxygen suggests a pulmonary cause; below 100 mmHg suggests congenital heart disease.
- Duct-dependent lesions (transposition, pulmonary atresia, critical coarctation, interrupted aortic arch) need prostaglandin E1 at 0.05-0.1 micrograms/kg/minute; be prepared for apnoea.
- Screen all newborns with pulse oximetry at about 24 hours or before discharge.
Acquired disease
- Acute rheumatic fever uses the Jones criteria: two major, or one major plus two minor, plus evidence of preceding streptococcal infection. Major: carditis, polyarthritis, chorea, erythema marginatum, subcutaneous nodules. Secondary penicillin prophylaxis follows.
- Kawasaki disease: five days or more of fever plus four of five features (bilateral conjunctivitis, oral mucositis, polymorphous rash, extremity changes, cervical node over 1.5 cm). Give IVIG 2 g/kg plus aspirin; coronary artery aneurysm is the danger. Incomplete disease is common under 6 months.
- Endocarditis prophylaxis is reserved for prosthetic valves, previous endocarditis and unrepaired cyanotic disease.
Heart failure
Treat with diuretics, angiotensin-converting enzyme inhibitors and digoxin, but always treat the underlying lesion.
Worked example
A 6-week-old has poor feeding, tachypnoea, hepatomegaly and a murmur. This is heart failure, not colic. Measure blood pressure in all four limbs and palpate femoral pulses; weak femoral pulses with upper-limb hypertension point to coarctation, while a loud pansystolic murmur suggests a large ventricular septal defect. Echocardiography and antifailure therapy follow immediately.
Traps
Calling a murmur innocent in a child with failure to thrive, never palpating femoral pulses, and delaying IVIG in Kawasaki disease.