title: Gaseous and solid cerebral microembolization during proximal aortic anastomoses in off-pump coronary surgery: the effect of an aortic side-biting clamp and two clampless devices.
abstract: OBJECTIVE
  Intraoperative cerebral microembolism is a cause of cerebral dysfunction after cardiac surgery, and particulate microemboli are the most damaging. Using a new-generation transcranial Doppler ultrasound, we compared the number and nature of microemboli in patients undergoing off-pump coronary artery bypass grafting during performance of proximal anastomoses with three techniques: an aortic side-biting clamp and two clampless devices (the Enclose II device [Novare Surgical Systems, Inc, Cupertino, Calif] and the Heartstring II device [Guidant Corporation, Santa Clara, Calif]) developed to obviate the need for an aortic side-biting clamp, thereby reducing the number of cerebral microemboli.
  
  
  METHODS
  Bilateral continuous monitoring of the middle cerebral arteries was performed with a multirange, multifrequency transcranial Doppler device that both automatically rejects artifacts online and discriminates between solid and gaseous microemboli. Recordings were continuously undertaken during performance of 66 proximal aortic anastomoses in 42 patients. Thirty-five anastomoses were performed with an aortic side-biting clamp, 20 with the Enclose device, and 11 the Hearstring device.
  
  
  RESULTS
  Most microemboli occurred during application/insertion and removal of each device from the ascending aorta. The median number (interquartile range) of total microemboli was 11 (6-32) during side clamping, 11 (6-15) with the Enclose device, 40 (31-48) with the Heartstring device (P < .01). The proportion of solid microemboli was significantly higher in the side-clamp group (23%) compared with 6% and 1% in the Enclose and Heartstring groups, respectively (P < .01).
  
  
  CONCLUSIONS
  Avoidance of aortic side clamping results in a significant reduction in the proportion of solid microemboli detected with transcranial Doppler. As solid microemboli are probably the most damaging, use of the Enclose and Heartstring devices may represent an important strategy for minimizing cerebral injury during proximal aortic anastomoses.
authors.affiliation: Department of Cardiothoracic Surgery, John Radcliffe Hospital, Oxford, United Kingdom.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Guerrieri Wolf
authors.forename: Yasir
authors.initials: Y
authors.lastname: Abu-Omar
authors.forename: Bikram P
authors.initials: BP
authors.lastname: Choudhary
authors.forename: David
authors.initials: D
authors.lastname: Pigott
authors.forename: David P
authors.initials: DP
authors.lastname: Taggart
mesh_terms: D000368:Aged; D000714:Anastomosis, Surgical / Q000009:adverse effects / Q000295:instrumentation; D017023:Coronary Angiography; D047549:Coronary Artery Bypass, Off-Pump / Q000009:adverse effects* / Q000379:methods; D023921:Coronary Stenosis / Q000000981:diagnostic imaging / Q000401:mortality / Q000601:surgery*; D004618:Embolism, Air / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control*; D004867:Equipment Design; D004869:Equipment Safety; D005260:Female; D006801:Humans; D020766:Intracranial Embolism / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control*; D007431:Intraoperative Complications / Q000000981:diagnostic imaging / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D011336:Probability; D011379:Prognosis; D011446:Prospective Studies; D012016:Reference Values; D018570:Risk Assessment; D013525:Surgical Instruments; D015996:Survival Rate; D016896:Treatment Outcome; D017585:Ultrasonography, Doppler, Transcranial