Left Ventricular Dysfunction Persists in the First Week after Re-Warming following Therapeutic Hypothermia for Hypoxic-Ischaemic Encephalopathy

Abstract

Objectives: The aim of this study was to assess serial myocardial function in newborn infants receiving therapeutic hypothermia (TH) as treatment for moderate to severe hypoxic-ischaemic encephalopathy (HIE). Methods: Serial echocardiography was performed in 20 term infants receiving TH on days 1-3 and again after re-warming. Left ventricular (LV) fractional shortening, LV cardiac output, and tissue Doppler imaging-derived myocardial velocities and myocardial performance index were measured. Similar assessments were obtained from 20 well term infants within 48 h of birth. Results: LV fractional shortening (LVFS) was similar between cases and controls during all measurements (25.3% vs. 27.4%). The mean LV cardiac output on day 1 was significantly lower in cases (109 mL/kg/min) than in controls (162 mL/kg/min) but increased after re-warming (145 mL/kg/min). All myocardial velocities were significantly lower in cases on day 1, increased during TH, but LV indices remained consistently lower compared to controls even after re-warming. LV myocardial performance index was higher in cases compared to controls on day 1, improved during TH but remained abnormal after re-warming. The right ventricular myocardial performance index was similar between cases and controls. Conclusion: Among infants affected by moderate to severe HIE, LV function appears to be more affected than right ventricular function with LV dysfunction persisting after completion of TH. LVFS was not useful to determine dysfunction in this cohort.