Comparative Effects of Pulsatile and Nonpulsatile Flow on Plasma Fibrinolytic Balance in Pediatric Patients Undergoing Cardiopulmonary Bypass

In the brain, the components of the fibrinolytic system, tissue plasminogen activator (tPA) and its endogenous inhibitor plasminogen activator inhibitor-1 (PAI-1), regulate various neurophysiological and pathological responses. Fibrinolytic balance depends on PAI-1 and tPA concentrations. The objective of this study is to compare the effects of pulsatile and nonpulsatile perfusion on fibrinolytic balance in children undergoing pediatric cardiopulmonary bypass (CPB). Plasma PAI-1 antigen and tPA antigen were measured in 40 children (n=20 pulsatile and n=20 nonpulsatile group). Plasma samples (1.5mL) were collected (i) prior to incision, (ii) 1h after CPB, and (iii) 24h after CPB. PAI-1 and tPA levels were measured at each time point. PAI-1 and tPA levels were significantly increased at 1h after CPB, followed by a decrease at 24h. Nonpulsatile but not pulsatile CPB lowered PAI-1:tPA ratio significantly at 24h (median PAI-1:tPA ratio 4.63±0.83:1.98±0.48, P=0.03, for the nonpulsatile group and 4.50±0.92:3.56±1.28, P=0.2, for the pulsatile group). These results suggest that pulsatile flow maintains endogenous fibrinolytic balance after pediatric cardiopulmonary bypass. Further studies are needed to define the clinical significance of these differences.