Abstract: Apparatus and methods for performing retrograde perfusion, especially during cardiopulmonary bypass operations, including dedicated pediatric scaled apparatus for retrograde perfusion of an adult human organ, organ system, or limb, especially the brain, employing small scale oxygenators and heat exchangers such as are designed for pediatric surgery; also including methods and apparatus for retrograde cerebral perfusion, using nonselective infravalvular cannulation of the superior vena cava, estimating the efficacy of cerebral perfusion by monitoring fluid flow across a valve of an internal jugular vein, modification of inflow pressure and administration of pharmacologic agents, and increasing fluid flow into a brain by occlusion of an inferior vena cava distal to its junction with an azygos vein.