Impact of induced cardiac arrest on cognitive function after implantation of a cardioverter-defibrillator.

BACKGROUND AND OBJECTIVES Implantable cardioverter-defibrillators (ICD) were introduced in clinical practice in 1980 and they are considered the standard treatment for individuals at risk for fatal ventricular arrhythmias. To ensure proper working conditions, the energy necessary to interrupt ventricular tachycardia or ventricular fibrillation should be determined during implantation by a test called defibrillation threshold. For this test, it is necessary to induce ventricular fibrillation, which should be identified and treated by the device. The objective of the present study was to determine the frequency of cognitive dysfunction 24 hours after the implantation of a cardioverter-defibrillator. METHODS Thirty consecutive patients with indication of cardioverter-defibrillator (ICD) placement and 30 patients with indication of implantable pacemaker (PM) were enrolled in this study. Patients were evaluated at the following moments: 24 hours before placement of the ICD or PM with a pre-anesthetic evaluation form, Mini Mental State Examination (MMSE), and Confusion Assessment Method (CAM); during implantation of the ICD or PM, the following parameters were determined: number of cardiac arrests and total time of cardiac arrest. Twenty-four hours after placement of the device, the following parameters were evaluated: MMSE and CAM. RESULTS Differences in the frequency of altered MMSE and CAM scores between both groups before and after implantation were not detected by the Fisher Exact test. The mean time of cardiac arrest was 7.06 seconds, with a maximal of 15.1 and minimal of 4.7 seconds. CONCLUSIONS Induction of cardiac arrest during defibrillation threshold testing did not cause cognitive dysfunction 24 hours after implantation of the cardioverter-defibrillator.