Microemboli during coronary artery bypass grafting: Genesis and effect on outcome,☆☆,,★★,

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Abstract

Cerebral dysfunction after coronary artery bypass operations represents some to the most serious and costly complications of cardiac surgery, We used transcranial Doppler ultrasonography to detect and quantify the number of microemboli in the right middle cerebral artery of patients undergoing elective first coronary bypass operations ( n = 117) and second coronary bypass operations ( n = 10). We hypothesized that total microemboli were related to clinical outcome. A 2 MHz transducer was positioned in front of the ear above the zygomatic arch and depth gated to 50 mm. Microemboli were recorded as perturbations of the blood flow velocity in the middle cerebral artery and aurally monitored. Each episode of mircroembolism was specified both by clock time and as perfusion or surgical event. Forty-one patients (32%) completed neurophysiologic evaluation with a battery of tests for cognitive function. Anxiety states and traits were also assessed. The distribution of microembolism showed that there were three groups of patients <30 microemboli ( n = 83); 30 to 59 ( n = 24) >60 ( n = 24). Seven of 10 patients with cerebral complications (stroke, coma delirium, aberrant behavior) were in the >60 microemboli group. Those with cerebral complications had 20.7 ± 4.5 from perfusion and system symptoms had 95.5 ± 19.5 microemboli from perfusion and 36.0 ± 6.9 from surgical events. Neuropsychological scores were most often depressed for memory (73%), comprehension (49%) , attention (46%), and constructional ability (44%). The greatest change was in total score in the >60 microemboli group (-3.3 ± 0.6) compared with -1.1 ± 0.2 and 1.1 ± 0.2 for the 30 to 59 and <30 groups, respectively. The incidences of cardiac and pulmonary complications and mortality were different between those patients with <60 microemboli versus those with >60 microemboli group. We concluded that transcranial Doppler ultrasonography is a useful technique to quantify and detect the source of microemboli during coronary artery bypass operations and may be useful in assesing new operative stragteies, the quality of the perfusion, and poentially as an indicator for pharmacologic therapy in the operationg room in patients with high microemboli counts. (J THORAC CARDIOVASC SURG 1995;109:249-58)

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From the Cardovascular and Pulmonary Research Center, Alleghney-Singer Research Insitutea, and The Departments of Physchiaryb and Surgeryc and the Division of Nerologya Allehany General Hospital, Pittsburgh, Pa.

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Supported in part by the Allegeny-Singer Reseach Institue, the Departments of Surgery and Psychiarty and the Division of Neurulogy, Allegheny General Hospital, Pittsburgh, Pa.

Read at the Seventy-fourth annual meeting of the American Assocation for Thoracic Surgery, New York, N.Y., April 24-27, 1994.

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Address for reprints: Richard E. Clark, MD, Cardiovascular and Pulmonary Research Center, Allegheny-Singer Research Institute, 320 E. North Ave., Pittsburgh, PA 15212.

0022-5223/95 $3.00 + 0 12/6/61138