Evaluation of left ventricular function using various echocardiographic techniques in hypoxic neonates during...

The aim of this study was to evaluate left ventricular function in hypoxic neonates undergoing therapeutic hypothermia using echocardiography.

This multicenter, prospective, case-control, observational study involved 113 neonates, including 55 in the hypothermic group and 58 nonhypothermic controls. Echocardiographic measurements were taken by two neonatologist (NB and RB) during therapeutic hypothermia and after rewarming using various techniques.

There was a significant difference between the study group and controls in mean blood pressure (p <0.001) and heart rate (p = 0.004) during therapeutic hypothermia. Significantly higher post-rewarming heart rate was observed in the study group compared to controls (p <0.001). Significantly lower mean A-wave (A mv) (p = 0.04) and E-wave (E mv) (p = 0.003) mitral valve velocities, as well as reduced mitral annular plane systolic excursion (p <0.001), cardiac output (p <0.001), and left ventricular internal diameter in diastole (p <0.001) were observed in the study group compared to controls during therapeutic hypothermia. The mean left ventricular myocardial performance index was significantly higher in the study group (p = 0.006). Tissue Doppler imaging showed significantly lower left ventricular E' velocity (p <0.001) and E'/A' ratio during therapeutic hypothermia in the study group compared to controls. Left ventricular A' (p = 0.006), E' (p <0.001), and S' (p = 0.003) velocities were significantly lower, while myocardial performance index (p <0.001) was significantly higher in the study group during therapeutic hypothermia than after rewarming.

Hypothermic neonates exhibit more severe global impairment compared to healthy controls. This is reflected in higher myocardial performance index values and lower E'/A' ratio, which indicates diastolic dysfunction.