Single-ventricle physiology reduces cerebral oxygen delivery in a piglet model.

Background In single-ventricle physiology, cerebral blood flow and oxygen (O 2 ) delivery may be inadequate. This study tests the hypotheses that in acute univentricular physiology (1) cerebral blood flow increases inadequately to maintain O 2 delivery, (2) the brain is incapable of increasing O 2 extraction due to hypoxemia, and (3) cerebral O 2 delivery diminishes selectively in different brain regions. Material and Methods Univentricular physiology was created in 8 piglets, while 8 animals were sham controls. Aortopulmonary shunt, echocardiography-guided atrial septostomy, tricuspid valve avulsion, and pulmonary artery occlusion were performed to allow the left ventricle to support systemic and pulmonary circulations. Cerebral blood flow (microspheres), cerebral O 2 and lactate metabolism, and cerebral O 2 saturation were measured at baseline, 30 minutes, and 120 minutes after conversion to univentricular physiology. Results Cerebral blood flow increased in the cerebrum and subtentorium in controls ( p 2 delivery at 30 and 120 minutes was lower in univentricular physiology than in controls ( p = 0.05). Fractional oxygen extraction was unchanged in both groups. Cerebral O 2 consumption trended lower in univentricular physiology ( p = not significant), while it was unchanged in controls. Lactate cerebral metabolic rate (CMR Lactate ) increased at 30 and 120 minutes in both groups. The decline in O 2 delivery was variable, but present in nearly all brain regions. Conclusions This study confirms the hypothesis that, in univentricular physiology, hypoxemia and limited cerebral blood flow reduce cerebral O 2 availability in nearly all regions. These findings contribute to the understanding of brain abnormalities in infants with univentricular physiology.