Cardiovascular performance of neonates with hypoxic-ischemic encephalopathy under therapeutic hypothermia evaluated by conventional and advanced echocardiographic techniques

This study aimed to evaluate hemodynamic and ventricular performance of neonates with hypoxic-ischemic encephalopathy under therapeutic hypothermia using conventional and advanced echocardiographic techniques. This was an observational, prospective study including 22 neonates with hypoxic-ischemic encephalopathy matched with 22 healthy neonates. The echocardiographic studies were performed during hypothermia and after rewarming. Echo parameters included ejection and shortening fractions, 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 and right ventricular global longitudinal strain, left ventricular circumferential and radial strain, twist and torsion. Results: Left ventricular ejection and shortening fractions did not change during therapeutic hypothermia (hypothermia:72±7% and 39±6%, rewarming:74±5% and 41±5%, p=0.21 and p=0.25) however they were higher after rewarming compared to the control group (70±5%, p=0.003 and 36±4%, p=0.002 respectively). There was no difference on left ventricular global longitudinal, circumferential and radial strain, twist and torsion during the therapeutic process. Higher pulmonary artery systolic pressure and worse right ventricular global longitudinal strain were observed in the study group (hypothermia:44±24mmHg and 17,9±4,9%, rewarming:53±24mmHg and 19,2±3,8%, control group:29±11mmHg and 20,5±2,2% respectively). Conclusion : Left ventricular parameters remain stable during the two phases of therapeutic hypothermia what suggests no impact of the induced cooling on left ventricular systolic function. Right ventricular global longitudinal strain was the only echocardiographic tool able to identify some degree of systolic function impairment during therapeutic hypothermia. This could be explained by the pulmonary hypertension identified in the study group during this period.