Circle of Willis and Cryonics Perfusion

Circle of Willes in Cryonics Perfusion

The carotid and vertebral arteries are the main arteries that supply blood to the brain. The Circle of Willis, a circular arterial system in the brain, connects blood coming in via the carotid and basilar arteries (which are fed by the vertebral). The Circle of Willis is a circular arterial structure in the brain that connects blood flowing from the carotid arteries with blood flowing into the basilar artery (which is fed by the vertebral arteries). Numerous studies have shown that most people do not have a complete Circle of Willis. In a 1998 study of 150 healthy adults, only 42% of the cases showed a Circle of Willis. This was more common in females and younger people [RADIOLOGY Krabbe Hartkamp MJ; 207 :103-111 (1998)]. In a slightly more encouraging study of 118 volunteers aged 65-68, a Circle of Willis was found to be complete in 47% of cases.

In cryonics, it was believed that perfusion of blood into the carotid but not the vertebral vessels would result in an incomplete perfusion of brain if the Circle of Willis were not complete. If both posterior communicating arteries were missing, perfusing through only the carotids would result in the blood not reaching the parts of the cerebral arteries that supply the posterior cerebral arteries. In the 1998 study, 11% of the participants were missing both posterior communicating arteries. This was also the case in the 2002 study.

A 2008 study that showed Circle of Willis completed in only 40 of 99 patients did not find any cases of insufficient cerebral perfusion during functional tests of the patients who received unilateral cerebral perfusion. The authors concluded that the \”extracranial circulation\” is an alternative to the Circle of Willis in cerebral crossperfusion. [EUROPEAN JORNAL OF CARDIOTHORACIC SURGEORY; Urbanski, PP 33:402-408 (2007)]. The authors concluded that although persons with missing posterior communication arteries can easily have pathways on opposite sides of their brain, other variations of Circle of Willis incompatibility would prevent perfusion between hemispheres [EUROPEAN JOURNAL OF CARDIOTHORACIC SURGERY; Urbanski, PP; 33:402-408 (2008)].


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