The effects of pneumothorax on defibrillation thresholds during pectoral implantation of an active can implantable cardioverter defibrillator.

Pneumothorax has previously been reported to increase defibrillation thresholds and lead impedance in monophasic systems. This article demonstrates a case using an active can system in which the lead impedance between the right ventricular defibrillation coil and the device improved from 70 omega with pneumothorax to 48 omega after resolution. The defibrillation threshold also improved from > 30 J to < or = 10 J after the pneumothorax had resolved. We conclude that acute pneumothorax can increase the transthoracic lead impedance and defibrillation thresholds; however, with resolution both parameters can return to acceptable levels with an active can system.