Pediatric Physiologic Pulsatile Pump Enhances Cerebral and Renal Blood Flow During and After Cardiopulmonary Bypass *†‡Akif Ündar, ‡Takafumi Masai, ‡Erik A. Beyer, §Jan Goddard-Finegold, †Mary Claire McGarry, and *†§Charles D. Fraser, Jr. *Division of Congenital Heart Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine; †Congenital Heart Surgery Service, Texas Children’s Hospital; ‡Cullen Cardiovascular Surgical Research Laboratories, Texas Heart Institute; and §Department of Pediatrics and Pediatric Neurology, Baylor College of Medicine, Houston, Texas, U.S.A. Abstract: Controversy over benefits of pulsatile flow after pediatric cardiopulmonary bypass (CPB) continues. Our study objectives were to first, quantify pressure and flow waveforms in terms of hemodynamic energy, using the energy equivalent (EEP) formula, for direct comparisons, and second, investigate effects of pulsatile versus nonpul- satile flow on cerebral and renal blood flow, and cerebral vascular resistance during and after CPB with deep hypo- thermic circulatory arrest (DHCA) in a neonatal piglet model. Fourteen piglets underwent perfusion with either an hydraulically driven dual-chamber physiologic pulsatile pump (P, n  7) or a conventional nonpulsatile roller pump (NP, n  7). The radiolabeled microsphere tech- nique was used to determine the cerebral and renal blood flow. P produced higher hemodynamic energy (from mean arterial pressure to EEP) compared to NP during normo- thermic CPB (13 ± 3% versus 1 ± 1%, p < 0.0001), hypo- thermic CPB (15 ± 4% versus 1 ± 1%, p < 0.0001) and after rewarming (16 ± 5% versus 1 ± 1%, p < 0.0001). Global cerebral blood flow was higher for P compared to NP dur- ing CPB (104 ± 12 ml/100g/min versus 70 ± 8 ml/100g/min, p < 0.05). In the right and left hemispheres, cerebellum, basal ganglia, and brainstem, blood flow resembled the global cerebral blood flow. Cerebral vascular resistance was lower (p < 0.007) and renal blood flow was improved fourfold (p < 0.05) for P versus NP, after CPB. Pulsatile flow generates higher hemodynamic energy, enhancing ce- rebral and renal blood flow during and after CPB with DHCA in this model. Key Words: Pulsatile flow— Cardiopulmonary bypass—Energy equivalent pressure— Cerebral blood flow—Renal blood flow—Deep hypother- mic circulatory arrest. The use of deep hypothermic circulatory arrest (DHCA) with hypothermic cardiopulmonary bypass (CPB) is required to repair complex congenital heart defects. Several investigators have reported cerebral and renal complications after DHCA (1–4). The ma- jority of pediatric cardiac centers use nonpulsatile perfusion during CPB (5). We believe that one of the causes of organ dysfunction after CPB with DHCA is the use of nonpulsatile flow (6). Although there is sufficient evidence for the superiority of pulsatile perfusion over nonpulsatile perfusion for pediatric patients in the literature, the controversy over pul- satile versus nonpulsatile flow still continues (6–12). One of the most important factors in this contro- versy is the lack of complete quantification of pulsa- tile and nonpulsatile pressure-flow waveforms dur- ing CPB (13–15). Most of the investigators quantify pulsatile flow in terms of pulse pressure. We believe that this approach is inadequate because the genera- tion of pulsatile flow depends on an energy gradient rather than a pressure gradient (13–16). The energy equivalent pressure (EEP) formula is the best tool to quantify different modes of perfusion because it con- tains both pressure and pump flow waveforms (16). The objectives of this study were first, to investi- Received June 2002. Presented in part at the 9th Congress of the International So- ciety for Rotary Blood Pumps, held August 17–20, 2001, in Se- attle, Washington. Address correspondence and reprint requests to Dr. Akif Ün- dar, Texas Children’s Hospital/Baylor College of Medicine, Con- genital Heart Surgery, 6621 Fannin Street, Mail Code WT 19345- H, Houston, TX 77030-2399, U.S.A. E-mail: aundar@bcm.tmc. edu Artificial Organs 26(11):919–923, Blackwell Publishing, Inc. © 2002 International Society for Artificial Organs 919