Acute Adaptation to Volume Unloading of the Functional Single Ventricle in Children Undergoing Bidirectional Glenn Anastomosis

Objective. Volume unloading of the functional single ventricle after a bidirectional Glenn anastomosis (BDG) prior to 1 year of age leads to improved global ventricular function as measured by the myocardial performance index (MPI), a Doppler-derived measurement of combined systolic and diastolic ventricular function. Systolic function remains unchanged after BDG according to previous studies; however, acute changes in global and diastolic function have not been previously investigated in this cohort. Our objective was to assess the short-term effects of the BDG on global ventricular function in patients with a functional single ventricle. Design. Echocardiograms to obtain MPI, isovolumic contraction time, and isovolumic relaxation time were performed at four time periods: in the operating room, in the operating room prior to BDG, shortly after separation from cardiopulmonary bypass, less than 24 hours postoperatively, and either prior to hospital discharge or at the first clinic follow-up visit. Results. Twenty-six patients were enrolled. There was significant ventricular dysfunction noted shortly after separation from cardiopulmonary bypass, median MPI 0.63 (0.39–0.81), that persisted in the short term postoperatively median MPI 0.50 (0.40–0.63). Isovolumic contraction time did not change, however, isovolumic relaxation time was significantly prolonged following BDG. Conclusion. In the postoperative patient after BDG, systolic function is preserved; however, there is evidence of diastolic and global ventricular dysfunction, at least in the short term.