• Sigrid Baumgartner, Monika Olischar, Martin Wald, Tobias Werther, Angelika Berger, Thomas Waldhör, Georg Fischer, and Ulrike Salzer-Muhar.
• Department of Pediatrics and Adolescent Medicine, Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Medical University of Vienna, Vienna, Austria.
• Pediatr. Res. 2018 May 1; 83 (5): 1016-1023.

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

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