Background. The purpose of this study was to determine the feasibility of differential perfusion of the aortic arch and descending aorta during cardiopulmonary bypass using a cannula designed for aortic segmentation. Methods. Pigs weighing 57 kg (n = 8), underwent cardiopulmonary bypass using the dual lumen aortic cannula. An inflatable balloon separated proximal (aortic arch) and distal (descending aorta) ports. During differential perfusion, the aorta was segmented and the arch and descending aorta perfused differentially using parallel heat exchangers. Ability to independently control brain and body temperature, cardiopulmonary bypass flow rate and mean arterial blood pressure was determined. Results. During differential perfusion cerebral hypothermia (27°C) with systemic normothermia (38°C) was established in 23 minutes. Independent control of arch and descending aortic flow and mean arterial blood pressure was possible. Analysis of internal jugular venous O2 saturation data indicated an increase in the ratio of cerebral O2 supply to demand during differential perfusion. Conclusions. A cannulation system segmenting the aorta allows independent control of cerebral and systemic perfusion. This device could provide significant cerebral protection while maintaining the advantages of warm systemic cardiopulmonary bypass temperatures. (C) 2000 by The Society of Thoracic Surgeons.