Patterns of Segmental Strain of the Left Ventricle in Extremely Premature Infants

Extremely premature newborns are predisposed to cardiovascular complications due to a number of factors, including myocardial immaturity, hemodynamic changes, and iatrogenic effects. There are few studies on myocardial strain in extremely premature infants during the early neonatal period. The objective of study was to assess the left ventricular (LV) segmental strain in extremely premature newborns during the early neonatal period by employing speckle-tracking echocardiography (STE). This prospective study examined 65 newborns with no signs of hemodynamic impairment during the first 72 h of life. The cohort had a range of birth weights (600-1500 g) and gestational ages (24-35 weeks). The peak strain in 18 LV segments during systole (peak S and time to peak S), and throughout the cardiac cycle (peak G and time to peak G), and during early systolic pre-stretch (peak P and time to peak P) were assessed in the longitudinal, circumferential, and radial directions. We obtained percentile tables of segmental strain characteristics in the longitudinal, circumferential, and radial directions. No dependence of segmental strain on the birth weight, gestational age, or arterial duct closure was found. A positive gradient of the longitudinal strain magnitude was observed from the base to the apex. The highest circumferential and radial strain were observed in LV septum. This study is the first to register and compare the longitudinal, circumferential, and radial LV strain using STE in extremely premature infants with no signs of hemodynamic disturbances during the first 72 h of life. Reference values for segmental strain were established.