Background: Phototherapy has been reported to alter blood flow to various tissues.
Objective: To evaluate the effects of phototherapy on the coronary blood flow in healthy, full term, jaundiced neonates.
Design/Methods: Peak diastolic velocity (Vd), diastolic time velocity integral (TVId) as a measure of flow, and flow index (FI) (TVId x heart rate) in the left main (LM) and left anterior descending (LAD) were studied with Doppler ultrasound before, during and post phototherapy in 19 term jaundiced infants (study group) and in a matched control group (25 neonates).
Results: Mean Vd in the LM and in the LAD, and the TVId in the LM were significantly lower during phototherapy compared with post phototherapy (22.5±6.9 vs. 25±6.3 cm/sec, 17.3±4.9 vs. 20.4±5.8 cm/sec, and 4.2±1.4 vs. 4.5±1.1 cm, respectively; p<0.05). Vd and TVId during phototherapy were also significantly lower in the LAD compared with the control group (17.3±4.9 vs. 21.5±4.7 cm/sec and 3.0±1.1 vs 3.8±0.8 cm; p<0.05). FI was significantly lower in the LAD compared to the control group (405.6±131.3 vs. 494.7±174.0 cm/min; p<0.05). Measures of cardiac output did not change throughout the study. Significantly more infants demonstrated larger than 10% recovery in TVId and Vd in the LM post phototherapy compared with during phototherapy.
Conclusions: Our study may indicate a transient decrease in coronary blood flow and velocity with no significant changes in measures of cardiac output in healthy neonates during phototherapy. The clinical significance of these alterations, suggesting a "steal" effect from the coronary arteries, needs to be further evaluated
