Distribution of cerebral flow using retrograde versus antegrade cerebral perfusion

Background. This study compared now to the brain with retrograde and antegr ade cerebral perfusion during circulatory arrest. Methods. Twenty-four rabbits were injected with 5 mCi of technetium-99 macr oaggregated albumin, a tracer trapped in the capillaries. Group I (n = 6) w ere maintained normothermic, and the tracer was injected into the ascending aorta. Group II (n = 6) were maintained normothermic, and underwent cannul ation of the superior vena cava (SVC), exsanguination through the aorta, an d injection of the tracer into the SVC, which was proximally occluded. In g roup III (n = 6), the animal was cooled to 25 degrees C. The animal was exs anguinated through the aorta and tracer was injected into the ascending aor ta. In group IV (n = 6), animals were cooled to 25 degrees C. The animal wa s exsanguinated through the ascending aorta and tracer was injected into th e SVC. Three animals (group V) were exsanguinated through the ascending aor ta and a retrograde venogram of the SVC was performed. Scintigraphy of grou ps I to IV was carried out on a digital gamma camera. Brain trapping of tra cer was graded from 0 to 5, with 0 being no tracer in the brain and 5 being dominant tracer trapping in the brain. Results. Tracer trapping in the brain showed group I, 3.67 +/- 0.82; group II, 0; group III, 4.67 +/- 0.41; group IV, 0.17 +/- 0.41 (p < 0.0001). Retr ograde venogram of the SVC showed now into the cerebral veins. Conclusion. Retrograde now through the SVC reaches the cerebral venous syst em. Flow arriving in retrograde fashion does not go through the capillary s ystem.