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 (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.

Short‐term ventriculo‐arterial coupling and myocardial work efficiency in preterm infants undergoing percutaneous patent ductus arteriosus closure

“…To our knowledge there are two previous studies describing arterial elastance, end-systolic elastance, and ventriculoarterial coupling in preterm infants (Baumgartner et al, 2018;Waal et al, 2017). Baumgartner et al described a gradual decrease in VAC over the first few weeks of life, suggestive of an adaptation from a high stroke work state in early transition to a more energy-efficient pump later (Baumgartner et al, 2018). VAC was comparatively lower in patients with hemodynamically significant PDA shunts versus patients with no PDA throughout the transitional period up to 10 weeks of life (Baumgartner et al, 2018;Waal et al, 2017).…”

“…In adults, maximal energetic efficiency occurs at a VAC around 0.5, maximal stroke work occurs when the ratio is close to 1, and an optimal coupling ratio at rest is between 0.7 and 1 (Chantler & Lakatta, 2012 ; Prsa et al, 2014 ). Children have proportionally higher E ES and lower VAC than adults such that the normative data for term infants is close to 0.5 (Baumgartner et al, 2018 ). To our knowledge there are two previous studies describing arterial elastance, end‐systolic elastance, and ventriculo‐arterial coupling in preterm infants (Baumgartner et al, 2018 ; Waal et al, 2017 ).…”

“…Children have proportionally higher E ES and lower VAC than adults such that the normative data for term infants is close to 0.5 (Baumgartner et al, 2018 ). To our knowledge there are two previous studies describing arterial elastance, end‐systolic elastance, and ventriculo‐arterial coupling in preterm infants (Baumgartner et al, 2018 ; Waal et al, 2017 ). Baumgartner et al described a gradual decrease in VAC over the first few weeks of life, suggestive of an adaptation from a high stroke work state in early transition to a more energy‐efficient pump later (Baumgartner et al, 2018 ).…”

“…All the VAC parameters were obtained by estimating end‐systolic pressure (ESP) and using ventricular volumes obtained from the TnECHOS. We used different methods to calculate ESP as per the following formulas: ESP 1 = SBP × 0.9 (Baumgartner et al, 2018 ; Chowdhury et al, 2016 ; Kelly et al, 1992 ), ESP 2 = [(2 × SBP) + DBP]/3 (Engel et al, 2014 ; Kelly et al, 1992 ; Kuznetsova et al, 2012 ), and ESP 3 = [(SBP × 0.4) + (DBP × 0.6) + 1.4] (Iwahara et al, 1991 ), where SBP represents the systolic BP and DBP represents the diastolic BP. The first method (ESP 1 ) has been described more often in the literature and therefore was used as the primary outcome in this study.…”

“…To estimate E A, we used two different methods to estimate stroke volume obtained by echocardiography methods. E A calculations have been previously described using M‐mode measurements (Baumgartner et al, 2018 ; Engel et al, 2014 ). However, due to the geometrical assumptions that are required to estimate volumes using M‐mode and its specific limitations in neonates, we chose two alternate methods that have higher reliability (Cameli et al, 2016 ; Zacà et al, 2010 ).…”