Cardiovascular Performance in Neonates with Hypoxic-Ischemic Encephalopathy Under Therapeutic Hypothermia: Evaluation by Conventional and Advanced Echocardiographic Techniques

Abstract

This study aimed to evaluate the hemodynamic and ventricular performance of neonates with hypoxic-ischemic encephalopathy (HIE) undergoing therapeutic hypothermia using conventional and advanced echocardiographic techniques. This observational, prospective study included 22 neonates with HIE matched with 22 healthy neonates. Echocardiographic studies were performed 24 h after achieving target temperature during hypothermia and 24 h after rewarming. Evaluated echocardiographic parameters included ejection fraction (EF), shortening fraction (SF), right ventricular fractional area change, biventricular Tei index, right ventricular s' wave velocity, tricuspid annular plane systolic excursion, biventricular stroke volume and cardiac output, left ventricular (LV) and right ventricular (RV) global longitudinal strain (GLS), LV circumferential and radial strain, LV twist, and LV torsion. LV EF and SF did not change significantly between the hypothermia and rewarming periods (EF:73 ± 7% vs. 74 ± 5%, p = 0.21; SF:39 ± 6% vs. 41 ± 5%, p = 0.26); however, both were higher after rewarming compared to the control group (EF:70 ± 5%, p = 0.003; SF:36 ± 4%, p = 0.002). There were no significant differences in LV GLS, circumferential and radial strain, twist, and torsion between the HIE and control groups. Pulmonary artery systolic pressure (PASP) and RV GLS were worse in the study group compared to the control group (PASP: hypothermia 45 ± 24 mmHg, p = 0.01; rewarming 53 ± 34 mmHg, p = 0.01; control group 29 ± 11 mmHg; RV GLS: hypothermia 18 ± 5%, p = 0.02; rewarming: 18 ± 4%, p = 0.01; control group 21 ± 2%). Therapeutic hypothermia appears to have no detrimental impact on LV systolic function. RV GLS was the only parameter that demonstrated impaired RV systolic function during therapeutic hypothermia, likely due to elevated PASP.

Keywords: Cardiac function/echocardiography; Hypoxic-ischemic encephalopathy; Neonate; Therapeutic hypothermia.