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Texas Children's Hospital HandbookTexas Children's Hospital Handbook

Section 4. Neonatology > 

Chapter 32. Cardiology

Topics Discussed: airway management; alprostadil; arterial blood gas; blood circulation; cardiac catheterization; cardiology; cardiovascular examination and evaluation; congenital heart defect; congenital heart disease; electrocardiogram; fetus circulation; hyperoxia; indomethacin; neonatal circulation; neonatology; patent ductus arteriosus; pediatric cardiology; prenatal testing; vasoconstrictor agents.
Excerpt:"
  • Fetal circulation (parallel) in transition to complete adult circulation (series)
  • Is essentially a complete adult circulation in series, but with PDA and patent foramen ovale
  • Potential for shunting exists, determined by relation between SVR and PVR
  • Determinants of SVR
    • Intrinsic autoregulatory mechanisms
    • Environmental temperature
    • Radiant warmer–induced vasodilation
  • Determinants of PVR
    • Alveolar hypoxia
    • Reduced total pulmonary vascular bed
    • Sensitization of pulmonary vascular bed by sustained asphyxia
  • Large PDA can be diagnosed relatively accurately based on clinical findings.
  • Small PDA usually requires an echocardiogram with Doppler, because findings may be similar to pulmonary disease or sepsis.
  • Clinical findings of moderate to large PDA:
    • Hypotension
    • Murmur (Continuous, "machinery"-like, may be intermittent)
    • Heart failure (Poor feeding, apnea, respiratory failure)
    • Wide pulse pressure (>25 mm Hg)
    • Hyperdynamic precordium
    • Bounding pulses (± Palmar pulses, prominent pedal pulses)
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