1. Clinical Overview
Clinical Overview
Almost every neonatal cardiac problem is legible if you know the embryology (which structures can be abnormal) and the transitional physiology (when and how abnormalities present). Timing is diagnosis: a duct-dependent lesion becomes an emergency as the ductus closes; a left-to-right shunt becomes heart failure as pulmonary vascular resistance falls.
2. Key Clinical Points
Key Clinical Points
- Timing is diagnosis: duct-dependent lesions decompensate in the first days as the ductus closes; left-to-right shunts cause heart failure over the first weeks as PVR falls.
- Acyanotic large left-to-right shunts (VSD, PDA, AVSD) → pulmonary overcirculation and congestive heart failure (tachypnea, sweating with feeds, poor weight gain, hepatomegaly).
- A 'septic-looking' term neonate in shock may have a duct-dependent systemic lesion (HLHS, critical coarctation, interrupted arch) — PGE1 may be lifesaving; weak femorals/arm-leg BP gradient suggest coarctation.
- SVT is the commonest neonatal arrhythmia (narrow-complex, rate >220, minimal variability): vagal maneuvers/adenosine if stable, synchronized cardioversion if unstable.
- Embryology-syndrome clustering: conotruncal (outflow) defects with 22q11.2 deletion; endocardial cushion (AVSD) defects with trisomy 21.
2+. The Murmur in a Well Newborn (Baylor Ed. 33)
A murmur is one of the commonest abnormal findings in an otherwise well neonate, and in an asymptomatic infant the likelihood that it reflects congenital heart disease is under 10%. The skill is knowing which ones to chase — and remembering that severe heart disease can be completely silent, so a normal auscultation never excludes it.
| Murmur | When and where | Character and meaning |
|---|
| Ductus arteriosus | Usually day 1; cardiac base and over the left scapula; typically gone by day 2 as the duct closes functionally | Left-to-right ductal flow as PVR falls — mid-systolic and crescendo, sometimes continuous. Examine serially; work up if it persists or the infant becomes symptomatic. |
| Peripheral pulmonary branch stenosis | Base and lung fields, radiating to the axillae and back | Benign turbulence from rapidly falling PVR, the calibre step between main and branch pulmonary arteries, and the acute branching angle. |
| Outflow obstruction | First day; left or right upper sternal border | Grade 2–3 systolic — pathological until proven otherwise. |
| Ventricular septal defect | Often absent on the first exam, emerging late on day 1 or on day 2–3 as PVR falls; mid-to-lower left sternal border | Harsh, high-pitched, often obliterating S1 — may be dismissed as a flow murmur at first. |
| Atrial septal defect | Rarely heard in the first week | Increased-flow murmurs appear later. |
Who needs a workup, and what it is
- Hear the murmur in context: general appearance, respiratory rate and work of breathing, peripheral perfusion, central cyanosis, upper and lower limb pulses, and inspection and palpation of the precordium.
- No workup usually needed: grade 1–2, not radiating significantly, and not heard over the ventricular outflow tracts.
- Work up: murmurs grade 2–3 or louder with extensive radiation, and any murmur heard best over the ventricular outflow tracts.
- First steps: pre- and post-ductal saturations in room air and four-extremity blood pressures. Then, as indicated, chest radiograph for heart size, ECG, echocardiography and cardiology consultation.
3. References to Verify
- 1.The Neonatal Bedside — Part VI: The Cardiovascular Newborn (Chs. 31–35).
- 2.AHA/AAP neonatal cardiovascular and arrhythmia references.
- 3.Prostaglandin E1 stabilization of duct-dependent lesions.