CEREBRAL EMBOLI DURING CARDIAC-SURGERY IN CHILDREN

Background: Microemboli occur commonly during cardiac surgery in adult s, and, when present, increase the risk of neuropsychological deficits . Their incidence and significance during correction of congenital hea rt disease is unknown. The authors hypothesized that microemboli would occur before bypass with right-to-left cardiac shunts and would also occur in large numbers when the aortic crossclamp was released in chil dren during repair of congenital heart defects. Methods: In 25 childre n studied with carotid artery Doppler, embolic signals were counted an d timed in relation to 13 intraoperative events, Patients were classif ied as either at high risk (obligate right-to-left shunt or uncorrecte d transposition of the great arteries) or at low risk (net left-to-rig ht shunt or simple obstructive lesions) for paradoxical (venous to art erial) emboli. Results: The median number of emboli detected was 122 ( range, 2-2,664). Forty-two percent of all emboli were detected within 3 min of release of the aortic crossclamp. The high-risk group had sig nificantly more emboli (median, 66; range, 0-116) during the time inte rval before cardiopulmonary bypass than did the low-risk group (median , 8; range, 0-73), with P < 0.01. There was no significant difference between the high-and low-risk groups in the total number of emboli det ected. There was no apparent association between number of emboli and gross neurologic deficits. Conclusions: Microemboli can be detected in the carotid arteries of children undergoing repair of congenital hear t disease and are especially prevalent immediately after release of th e aortic crossclamp. The role of emboli in causing neurologic injury i n children undergoing repair of congenital heart disease remains to be determined.