Neuronal Injury After Repeated Brief Cardiac Arrests During Internal Cardioverter Defibrillator Implantation Is Associated With Deterioration of Cognitive Function

To determine the degree of neurocognitive dysfunction after placement of internal cardioverter defibrillators (ICD) and its relationship to the extent of neuronal injury, we studied 42 patients undergoing ICD (n = 21) or pacemaker (PM) insertion (control patients, n = 21). The Mini Mental State Examination, the Trailmaking A test and the forward and backward Digit Span tests were used and P300 latencies were determined preoperatively and postoperatively. Serum neuron-specific enolase (NSE) was determined before and at the end of, as well as 2, 6, and 24 h after surgery. Preoperatively, PM patients scored worse in the Digit Span backward and the Trailmaking tests and showed prolonged P300 latencies. Postoperatively, the Digit Span backward scores declined and NSE levels increased only in the ICD group (P ≤ 0.05). The difference between preoperative and postoperative Digit Span backward scores correlated with the increase in serum NSE levels (r2 = 0.3, P ≤ 0.05). Moreover, P300 latencies increased in 13 of 17 ICD patients, but decreased in 7 of 10 PM patients (P ≤ 0.05). PM patients even improved in the Trailmaking test (P ≤ 0.05). Neuronal injury from even brief periods of global brain ischemia seems to be associated with deteriorating neurocognitive function.