IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR - EVALUATION OF CLINICAL NEUROLOGIC OUTCOME AND ELECTROENCEPHALOGRAPHIC CHANGES DURING IMPLANTATION

During placement of implantable cardioverter-defibrillators, ventricul ar arrhythmias are induced to test the function of the devices. Althou gh cerebral hypoperfusion and ischemic electroenephalographic changes occur in patients while implantable cardioverter-defibrillators are be ing tested, no investigation has assessed neurologic outcome in these patients. Nine patients having either implantation or change of an imp lantable cardioverter-defibrillator underwent neurologic examination a nd neuropsychometric tests before and after the operation. After induc tion of general anesthesia and insertion of implantable cardioverter-d efibrillator leads (when needed), ventricular fibrillation, ventricula r butter, or ventricular tachycardia, was induced by means of programm ed electrical stimulation. Implantable cardioverter-defibrillator test ing continued until satisfactory lead placement was confirmed. The int raoperative electroencephalographic recording was analyzed for evidenc e of ischemic change. In all, an electroencephalogram was recorded dur ing 50 periods of circulatory arrest. Mean duration of the arrest peri ods was 13.6 seconds. By means of conventional visual inspection of th e raw electroencephalogram, high-amplitude rhythmic delta or theta, vo ltage attenuation, or loss of fast frequency activity was observed in 30 of the arrests. By means of an automated technique of electroenceph alographic interpretation based on power spectral analysis, electroenc ephalographic changes were correctly identified in 26 of the arrests. The incidence of these electroencephalographic changes was dependent o n the arrest duration. The mean interval from arrest onset to electroe ncephalographic change was 7.5 seconds (standard deviation +/- 1.8 sec onds). In patients with electroencephalographic changes during multipl e arrests, no downward trend in this interval was detected in later ar rests and no evidence of persistent ischemic change aas observed in el ectroencephalograms recorded after the conclusion of implantable cardi overter-defibrillator testing.]Postoperative neurologic and neuropsych ometric testing was completed in eight patients, none of whom exhibite d a new neurologic deficit, exacerbation of a preexisting neurologic c ondition, or significant deterioration in neuropsychometric performanc e. We conclude that the brief arrest of cerebral circulation induced d uring insertion of an implantable cardioverter-defibrillator is not as sociated with permanent neurologic injury.