Retrograde cerebral perfusion — An experimental study to evaluate brain perfusion in non-human primates

Abstract

Lesions of the aorta, as well as the ascending, the aortic arch or the descending aorta have been recognized as far back as the sixteenth century (6). However, inspite of the development of cardiopulmonary bypass, the knowledge of different types of lesions and their etiologies, and the development of grafts and the various techniques, aortic surgery has remained an intriguing part of the cardiovascular surgery. The localization of the disease dictates the management of the operation, that, is, when the ascending aorta without the cerebral vessels is involved, or the aortic arch, or the descending or abdominal aorta different approaches with different precautions are necessary. Involvement of the aortic arch is the most challenging aspect of aortic surgery since the blood supply to the brain is affected, limiting the tolerance of normothermic total ischemia to 4 min (27). This tolerance is greatly improved during hypothermic conditions, hence, together with the development of cardiopulmonary bypass, techniques for deep hypothermia and circulatory arrest were introduced. In 1964, Borst (1) first described a successful intervention on the cerebral vessels with deep hypothermia at a nasopharyngeal temperature of 18 °C, using circulatory arrest for 16 min, a procedure which was devised by Griepp (9) and published in 1975. Nevertheless, even under deep hypothermia, circulatory arrest is limited to 45 min (10). The repair of an aortic arch in such a short time requires fast and skillful surgery without hesitation, putting the surgical team under considerable stress. Therefore, it is necessary to prolong the tolerance to circulatory arrest, using alternatives such as retrograde cerebral perfusion, first described in 1988 by our Japanese colleague Ueda (22) as a very promising technique. They reported an intervention on the aorta using circulatory arrest and “retrograde cerebral perfusion”. During the circulatory arrest period, the brain was perfused via the superior caval vein. Many clinical studies followed with satisfactory results. However, despite some experimental data (23), real investigation to maintain structural integrity of the brain and extensive studies on tissue perfusion were not reported until this year (15, 18). Extrapolation of these results is somewhat controversial, while these studies are performed on pigs or dogs. So we designed an animal study using non-human primates for investigation of tissue perfusion during retrograde cerebral perfusion.