Management of diaphragmatic myopotential oversensing in implantable cardioverter defibrillators

Inappropriate shocks remain a significant problem associated with implantable cardioverter defibrillators (ICDs). We reviewed 718 consecutive patients at Stanford University Medical Center and Kaiser-Santa Teresa Medical Center who underwent ICD implantation between January, 1997 and April, 2001 for clinically significant diaphragmatic myopotential sensing. A total of 718 initial ICD implants were performed (373 Medtronic, 337 CPI/Guidant, and 8 Ventritex/St. Jude). During a mean follow up time of 24.6 months, 5/718 (0.7%) patients had clinically significant oversensing of diaphragmatic myopotentials. In 2 cases, inappropriate shocks were received while in the remaining 3 cases the programmed detection criteria for VF was transiently satisfied. Of the 5 patients, 3 had dual chamber systems, all had transvenous integrated bipolar leads, and all were CPI-Guidant ICD systems. In 4 cases, the problem was corrected by decreasing the sensitivity of the ICD. In I case a new lead and generator was required. Oversensing of diaphragmatic myopotentials is a rare complication of ICD implantation and can usually be remedied by reprogramming the device to a less sensitive setting.