title: Some variations of the circle of Willis, important for cerebral protection in aortic surgery--a study in Eastern Europeans.
abstract: BACKGROUND
  During unilateral selective cerebral perfusion (SCP), via cannulation of the brachiocephalic trunk, the brain receives blood only through the right common carotid artery and the right vertebral artery. For perfusion of the contralateral (left) hemisphere it is counted on the competence of the circle of Willis (CoW). It is well known that variations of CoW are present in more than 50% of the people. Furthermore, these variations usually affect more than one vessel of the circle. The aim of the present work was to study the variations of CoW, which could have an impact on cerebral blood supply during unilateral SCP.
  
  
  METHODS
  We study 112 CoWs obtained from cadavers via routine dissection in the Department of Forensic Medicine of Medical University, Sofia. The external diameter of both vertebral arteries and all arteries that form CoW was measured with a caliper-gauge.
  
  
  RESULTS
  We identify the variations of CoW such as significant hypoplasy and/or lack of a branch of the circle. Bearing in mind the characteristics of the blood flow during unilateral SCP some of these variations were classified as significant during unilateral SCP. They were subdivided into groups according to most probable stroke site after unilateral SCP.
  
  
  CONCLUSIONS
  Because of the high percent of the variations, hemodynamically significant during unilateral SCP, a suggestion for routine preoperative CT-angio of CoW could be made. Furthermore, an intraoperative follow-up with NIRO, transcranial Doppler, EEG, and so forth could also be recommended.
authors: Department of Anatomy and Histology, Medical University, 1 G. Sofiiski Street, 1431-Sofia, Bulgaria. vassil_papanchev@yahoo.com
authors: Vassil
authors: V
authors: Papantchev
authors: Stanislav
authors: S
authors: Hristov
authors: Daniela
authors: D
authors: Todorova
authors: Emanuil
authors: E
authors: Naydenov
authors: Adrian
authors: A
authors: Paloff
authors: Dimitar
authors: D
authors: Nikolov
authors: Alexander
authors: A
authors: Tschirkov
authors: Wladimir
authors: W
authors: Ovtscharoff
mesh_terms: D020771:Anterior Cerebral Artery / Q000002:abnormalities; D001921:Brain / Q000098:blood supply; D002102:Cadaver; D002339:Carotid Arteries / Q000002:abnormalities; D002536:Cerebral Arteries / Q000002:abnormalities; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002941:Circle of Willis / Q000002:abnormalities*; D006801:Humans; D020769:Posterior Cerebral Artery / Q000002:abnormalities; D014711:Vertebral Artery / Q000002:abnormalities