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Ann Thorac Surg 1999;67:1069
© 1999 The Society of Thoracic Surgeons
a Harvard Medical School, West Roxbury VA Medical Center, 1400 VFW Parkway, West Roxbury, MA 02132, USA
Invited commentary
Although retrograde cerebral perfusion of arterialized blood has become an accepted clinical practice in some centers, the mechanism for cerebral protection during retroperfusion remains elusive. In the current article, Katz and colleagues set out to determine whether the manner in which the brain is perfused (antegrade versus retrograde) affects the distribution of cerebral blood flow during circulatory arrest. They demonstrated that during retrograde perfusion, blood did flow in a cephalad direction, however little, if any, blood reached the cerebral microcirculation. In contrast, antegrade perfusion, as anticipated, yielded physiologic cerebral blood flow.
Several studies have shown that retrograde delivery of blood to the cerebral venous sinuses is confounded by presence of venovenous and arteriovenous shunting; therefore, it is not clear whether the technique provides sufficient nutritive flow to maintain ongoing cerebral metabolism during hypothermic circulatory arrest. The present study by Katz and colleagues is in concert with these findings. In the clinical setting, retrograde cerebral perfusion is most commonly delivered through the superior vena cava alone. This study suggests that retroperfusion through the superior vena cava alone may never provide any substantive cerebral protection beyond the backwash of particulate debris and air.
This negative study does not preclude the possibility of effective cerebral retroperfusion. Total body, bicaval retroperfusion may be an attractive alternative and has achieved acceptable clinical results, but this method has yet to be studied as widely as the superior vena caval approach. At present, it is clear that the time-tested, standard techniques for cerebral protection during circulatory arrest have not been supplanted by either antegrade or retrograde cerebral perfusion. Retrograde perfusion is at best adjunctive to deep hypothermia and pharmacologic reduction of cerebral metabolic activity.
The search for optimal cerebral protection continues. The "true believers" in retrograde cerebral perfusion will continue to champion their cause but to date, the hypothesis has generated more heat than light.
Related Article
Ann. Thorac. Surg. 1999 67: 1065-1069.
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