Left ventricular pumping during the transition-adaptation sequence in preterm infants: impact of the patent ductus arteriosus.

BackgroundPostnatally, the immature left ventricle (LV) is subjected to high systemic afterload. Hypothesizing that LV pumping would change during transition-adaptation, we analyzed the LV in preterm infants (GA≤32+6), clinically stable or with a hemodynamically significant patent ductus arteriosus (hPDA) by applying a pump model.MethodsPumping was characterized by E (effective arterial elastance, reflecting afterload), E (end-systolic LV elastance, reflecting contractility), E/E coupling ratios, descriptive E:E relations, and E/E graphs. Data calculated from echocardiography and blood pressure were analyzed by diagnosis (S group: clinically stable, no hPDA, n=122; hPDA group, n=53) and by periods (early transition: days of life 1-3; late transition: 4-7; and adaptation: 8-30).ResultsS group: LV pumping was characterized by an increased E/E coupling ratio of 0.65 secondary to low E in early transition, a tandem rise of both E and E in late transition, and an E/E coupling ratio of 0.45 secondary to high E in adaptation; hPDA group: time-trend analyses showed significantly lower E (P<0.0001) and E (P=0.006). Therefore, LV pumping was characterized by a lower E/E coupling ratio (P=0.088) throughout transition-adaptation.ConclusionsIn stable infants, facing high afterload, the immature LV, enhanced by the physiological PDA, increases its contractility. In hPDA, facing low afterload, the overloaded immature LV exhibits a consistently lower contractility.