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Myocardial function during bradycardia events in preterm infants
Koert de Waal1, Nilkant Phad1, Nick Collins2
1Department of Neonatology, John Hunter Children's Hospital and University of Newcastle, Newcastle, NSW, Australia.
Early Human Development
|June 29, 2016
Summary
Transient bradycardia in preterm infants affects atrial contractility but maintains systolic function. Cardiac output is reduced during these events, with a compensatory increase observed afterward.
Area of Science:
- Neonatal cardiology
- Pediatric cardiovascular research
- Preterm infant physiology
Background:
- Transient bradycardia is common in preterm infants, often linked to apnea and hypoxemia.
- Sudden bradycardia without apnea may result from vagal stimulation.
- Point-of-care ultrasound is crucial for diagnosing cardiovascular issues in preterm infants.
Purpose of the Study:
- To investigate left ventricular function during bradycardia events in preterm infants.
- To analyze myocardial motion and deformation during bradycardia using speckle tracking.
- To understand the impact of bradycardia on systolic and diastolic parameters.
Main Methods:
- Retrospective analysis of a cardiac ultrasound database for bradycardia events.
- Utilized apical four or three chamber images before, during, and after bradycardia.
- Employed speckle tracking software to assess myocardial motion, deformation, and volume parameters.
Main Results:
- Fifteen bradycardia events were analyzed in 14 preterm infants (median gestational age 26 weeks).
- Heart rate decreased by an average of 43%; atrial diastolic function was reduced.
- Systolic contractility (longitudinal strain) was maintained, while ventricular volumes and ejection fraction remained unchanged.
Conclusions:
- Systolic contractility and stroke volume are preserved during mild to moderate bradycardia in preterm infants.
- Atrial contractility parameters are reduced, impacting diastolic function.
- Bradycardia transiently reduces cardiac output, followed by a compensatory increase.
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