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Left ventricular stroke volume and output in healthy term infants

P Winberg1, B P Lundell

  • 1Department of Pediatrics, Karolinska Institute, Sachs's Children's Hospital, Stockholm, Sweden.

American Journal of Perinatology
|July 1, 1990
PubMed

Insights

In healthy newborns, stroke volume, not heart rate, primarily determines left ventricular output. Low blood pressure after birth may enhance this relationship in neonatal circulation.

Area of Science:

  • Neonatal physiology
  • Cardiovascular adaptation
  • Pediatric cardiology

Background:

  • Understanding neonatal cardiovascular function is crucial for identifying potential issues.
  • Early postnatal adaptation involves complex changes in cardiac output and vascular resistance.

Purpose of the Study:

  • To investigate the determinants of left ventricular output in healthy term infants during the early postnatal period.
  • To assess the relationship between stroke volume, heart rate, and systemic vascular resistance.

Main Methods:

  • Noninvasive measurements of left ventricular output, stroke volume, and systemic vascular resistance in 16 healthy term infants.
  • Utilized range-gated Doppler for aortic blood flow velocity and 2D/M-mode echocardiography for cross-sectional area.
  • Calculated stroke volume by dividing left ventricular output by heart rate; systemic vascular resistance derived from mean arterial blood pressure.

Main Results:

  • A weak correlation was observed between heart rate and left ventricular output.
  • A strong positive association was found between stroke volume and left ventricular output.
  • A reciprocal relationship was identified between systemic vascular resistance and stroke volume.

Conclusions:

  • Stroke volume, rather than heart rate, is the principal determinant of left ventricular output in neonates.
  • The low postnatal systemic vascular resistance may amplify the influence of stroke volume on cardiac output in newborns.

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