VENTRICULAR DOMINANCE PATTERNS IN PRETERM INFANTS

OBJECTIVE: The purpose of the study was to determine EKG and 2-D echocardiographic criteria of ventricular dominance in preterm infants and select those by which ventricular dominance could be established by EKG alone. METHODS: A database was constructed from EKG and 2-D echocardiographic measurements on preterm infants ranging in gestational ages from 23 to 34 weeks and birth weights from 555-2490 g, and fullterm controls. Twelve-lead EKGs were obtained in the first 4 days of life in 12 preterm infants and in the first 24 hours of 4 controls. 2-D echocardiograms were performed with sweeps from the subcostal, parasternal, apical and suprasternal views and M-mode measurements in the short axis parasternal view on 11 of the preterm infants and 9 fullterm controls. RESULTS: A definite leftward QRS axis for the preterm infants (+90 degrees, preterm; +133.75 degrees, term; t = -5.63; p < 0.001) indicated a left ventricular (LV) dominance. But R/S in favor of LV dominance for preterm infants was apparent in V6 only. A pooled amplitude index for each ventricle based on R and S wave from V1, V2, V5, and V6 leads, showed LV dominance for the preterm infants with a trend toward RV dominance with increasing gestational age (F = 20.82; p < 0.001). RVD/LVED M-mode echo ratios confirmed the LV dominance in preterm infants. CONCLUSION: A healthy full term infant is born with RV dominance. LV dominance with a trend toward RV dominance with increasing gestational age was found in preterm infants by EKG and echo criteria.