title: Transmyocardial laser revascularization induces cerebral microembolization.
abstract: BACKGROUND
  Transmyocardial laser revascularization may vaporize fluid in the left heart, allowing bubbles to form. This study aimed to determine whether the laser pulse resulted in cerebral emboli and to examine changes in middle cerebral artery flow velocity and jugular bulb oxygen saturation (SjO2) during transmyocardial laser revascularization.
  
  
  METHODS
  Twelve patients (American Society of Anesthesiologists physical status III) were studied after the authors received institutional review board approval and the patients' informed consent. Monitored variables included mean arterial blood pressure (measured in millimeters of mercury), heart rate (measured as beats/min), and partial pressure of carbon dioxide (measured in millimeters of mercury). A 5-MHz transesophageal-sonography system was used to record intraventricular events after laser injection. Mean blood flow velocity (Vmean; measured in centimeters per second) was monitored in the middle cerebral artery using transcranial Doppler sonography, and SjO2 (expressed as a percentage) was measured using a fiberoptic thermodilution catheter placed in the right jugular bulb. Data were recorded before, during, and for 4 min after laser injection.
  
  
  RESULTS
  After laser injection, intraventricular echogenic contrast was seen in transesophageal-sonography, and 2-4 s later high-intensity signals (microemboli) appeared in the transcranial Doppler sonography spectra. As long as mean arterial pressure remained stable during the observation period, Vmean and SjO2 did not change.
  
  
  CONCLUSIONS
  These data show that microemboli can be detected after laser injection in the middle cerebral artery, although they do not effect Vmean and SjO2. The results suggest that these microemboli do not induce a global oxygen imbalance.
authors.affiliation: Department of Anesthesiology, University Hospital Eppendorf, Hamburg, Germany.
authors.forename: G
authors.initials: G
authors.lastname: von Knobelsdorff
authors.forename: P
authors.initials: P
authors.lastname: Brauer
authors.forename: P H
authors.initials: PH
authors.lastname: Tonner
authors.forename: F
authors.initials: F
authors.lastname: Hänel
authors.forename: H
authors.initials: H
authors.lastname: Naegale
authors.forename: H M
authors.initials: HM
authors.lastname: Stubbe
authors.forename: J S
authors.initials: JS
authors.lastname: Esch
mesh_terms: D000368:Aged; D002560:Cerebrovascular Circulation; D003327:Coronary Disease / Q000601:surgery*; D005260:Female; D006801:Humans; D002542:Intracranial Embolism and Thrombosis / Q000209:etiology*; D053685:Laser Therapy / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D009204:Myocardial Revascularization / Q000009:adverse effects*