TRANSMYOCARDIAL LASER REVASCULARIZATION INDUCES CEREBRAL MICROEMBOLIZATION

Background: Transmyocardial laser revascularization may vaporize fluid in the left heart, allowing bubbles to form. This study aimed to dete rmine whether the laser pulse resulted in cerebral emboli and to exami ne changes in middle cerebral artery flow velocity and jugular bulb ox ygen saturation (SjO(2)) during transmyocardial laser revascularizatio n. Methods: Twelve patients (American Society of Anesthesiologists phy sical status III) were studied after the authors received institutiona l review board approval and the patients' informed consent. Monitored variables included mean arterial blood pressure (measured in millimete rs of mercury), heart rate (measured as beats/min), and partial pressu re of carbon dioxide (measured in millimeters of mercury). A 5-MHz tra nsesophageal-sonography system was used to record intraventricular eve nts after laser injection. Mean blood flow velocity (V-mean; measured in centimeters per second) was monitored in the middle cerebral artery using transcranial Doppler sonography, and SjO(2) (expressed as a per centage) was measured using a fiberoptic thermodilution catheter place d in the right jugular bulb. Data were recorded before, during, and fo r 4 min after laser injection. Results: After laser injection, intrave ntricular echogenic contrast was seen in transesophageal-sonography, a nd 2-4 s later high-intensity signals (microemboli) appeared in the tr anscranial Doppler sonography spectra. As long as mean arterial pressu re remained stable during the observation period, V-mean and SjO(2) di d not change. Conclusions: These data show that microemboli can be det ected after laser injection in the middle cerebral artery, although th ey do not effect V-mean and SjO(2). The results suggest that these mic roemboli do not induce a global oxygen imbalance.