Left ventricular pumping during the transition-Adaptation sequence in preterm infants: Impact of the patent ductus arteriosus

Abstract

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 A (effective arterial elastance, reflecting afterload), E ES (end-systolic LV elastance, reflecting contractility), E A /E ES coupling ratios, descriptive E A:E ES relations, and E A /E ES 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 A /E ES coupling ratio of 0.65 secondary to low E ES in early transition, a tandem rise of both E A and E ES in late transition, and an E A /E ES coupling ratio of 0.45 secondary to high E ES in adaptation; hPDA group: Time-Trend analyses showed significantly lower E A (P<0.0001) and E ES (P=0.006). Therefore, LV pumping was characterized by a lower E A /E ES 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.