Introduction: It has been shown that neurocognitive function deteriorates after implantation of an ICD device . Furthermore, it was noted that serum neurone specific enolase (NSE), a marker of neuronal injury, increases after surgery . However, a direct relationship between these two alterations has not yet been evaluated.
Method: We therefore studied 19 ICD patients scheduled for elective ICD placement in monitored anaesthesia care because of drug-refractory ventricular fibrillation. NSE was determined preoperatively, immediately after surgery, and again 2, 6 and 24 hours after the operation. Additionally, concentration and attention were evaluated pre- as well as two days postoperatively with the help of the forward and backward Digit-Span Memory Test, in which the subject must absorb and recall a string of digits in the original and the reverse order, respectively. The highest obtainable score is 60 (forward test) and 50 points (backward test).
Results: On average, 3 episodes of ventricular fibrillation were induced in each patient during ICD testing. Baseline NSE determined before surgery was 9.9 ± 2.8 μg/L (mean ± SD). Increased levels could already be measured immediately after surgery (13.4 ± 6.1 μg/L, P < 0.05 vs. baseline, Repeated measures ANOVA with Bonferroni t-test). It remained elevated in the same range throughout the observation period. Concomitantly, the forward and the backward Digit-Span score declined from 44 to 37, and from 37 to 31 points, respectively.
Discussion: Obviously, these brief recurrent episodes of cerebral hypoperfusion during ICD placement are associated with neuronal injury. This may result in a deterioration of concentration and attention postoperatively without major neurological deficits.
1 Murkin JM, Baird DL, Martzke JS, et al. Cognitive dysfunction after ventricular fibrillation during implantable cardiovertor/defibrillator procedures is related to duration of the reperfusion interval. Anesth Analg
2 Dworschak M, Franz M, Czerny M, et al. Release of neuron-specific enolase and S100 after implantation of cardioverters/defibrillators. Crit Care Med