Intraoperative hypothermia increased defibrillation energy requirements.

We describe two patients with newly implanted automatic implantable cardioverter-defibrillators that had excessive defibrillation thresholds associated with hypothermia at intraoperative defibrillation threshold testing. Normal defibrillation threshold levels were obtained during postoperative non-invasive electrophysiology testing in an electrophysiology laboratory when the patients were normothermic. We hypothesize that inadvertent intraoperative hypothermia during device implantation may increase the defibrillation threshold.