title: Longer duration of cardiopulmonary bypass is associated with greater numbers of cerebral microemboli.
abstract: OBJECTIVE
  Many patients who undergo cardiac surgery assisted with cardiopulmonary bypass (CPB) experience cerebral injury, and microemboli are thought to play a role. Because an increased duration of CPB is associated with an increased risk of subsequent cerebral dysfunction, we investigated whether cerebral microemboli were also more numerous with a longer duration of CPB.
  
  
  METHODS
  Brain specimens were obtained from 36 patients who died within 3 weeks after CPB. Specimens were embedded in celloidin, sectioned 100 microm thick, and stained for endogenous alkaline phosphatase, which outlines arterioles and capillaries. In such preparations, emboli can be seen as swellings in the vessels. Cerebral microemboli were counted in equal areas and scored as small, medium, or large to estimate the embolic load (volume of emboli).
  
  
  RESULTS
  With increasing survival time after CPB, the embolic load declined (P<0.0001). (Lipid emboli are known to pump slowly through the brain.) Also with increasing time after CPB, the percentage of large and medium emboli became lower (P=0.0034). This decline is consistent with the concept that the emboli break into smaller globules as they pass through the capillary network. A longer duration of CPB was associated with increased embolic load (P=0. 0026). For each 1-hour increase in the duration of CPB, the embolic load increased by 90.5%.
  
  
  CONCLUSIONS
  Thousands of microemboli were found in the brains of patients soon after CPB, and an increasing duration of CPB was associated with an increasing embolic load.
authors.affiliation: Department of Radiology, Wake Forest University School of Medicine, Winston-Salem, NC27157-1088, USA.
authors.forename: W R
authors.initials: WR
authors.lastname: Brown
authors.forename: D M
authors.initials: DM
authors.lastname: Moody
authors.forename: V R
authors.initials: VR
authors.lastname: Challa
authors.forename: D A
authors.initials: DA
authors.lastname: Stump
authors.forename: J W
authors.initials: JW
authors.lastname: Hammon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D004620:Embolism, Fat / Q000209:etiology / Q000473:pathology; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects*; D006801:Humans; D020766:Intracranial Embolism / Q000209:etiology* / Q000401:mortality / Q000473:pathology; D008297:Male; D008875:Middle Aged; D013997:Time Factors