Neonatal left ventricular performance after vaginal delivery and cesarean section under general or epidural anesthesia.

Left ventricular systolic time intervals, plasma norepinephrine concentration, hematocrit, and blood pressure were recorded in infants delivered vaginally and by cesarean section from mothers under epidural or general anesthesia. Each group comprised 12 infants. Left ventricular ejection time and the preejection period were longer in infants delivered vaginally, although the concentrations of norepinephrine found were greater than those found in the cesarean section groups. Hematocrit and blood pressure were unrelated to the mode of delivery or the anesthetic technique. The isovolumic contraction time, however, was significantly shorter after epidural anesthesia 15.6 +/- 7.6 msec (mean +/- 1 SD) than after general anesthesia 20.5 +/- 8.0 msec at 30 minutes (p less than 0.05), 14.8 +/- 6.2 msec, and 20.9 +/- 5.7 msec at 2 hours respectively (p less than 0.001). These differences in left ventricular dynamics are probably related to the effects of anesthetics that have traversed the placenta rather than to mode of delivery.