INHIBITION OF BRADYCARDIA PACING CAUSED BY FAR-FIELD ATRIAL SENSING IN A 3RD-GENERATION CARDIOVERTER-DEFIBRILLATOR WITH AN AUTOMATIC GAIN FEATURE

The diagnostic accuracy of implantable cardioverter defibrillators may be improved by automatically adjusting gain algorithms, which in gene ral reduce the likelihood of oversensing while maintaining the ability to detect the low amplitude signals associated with ventricular fibri llation. We present a patient with a third-generation device who devel oped prolonged ventricular asystole arising as a complication of the a utomatic gain feature. During asystole the device automatically increa sed sensitivity in order to prevent undersensing of ventricular fibril lation, which in this case resulted in far-field sensing of atrial act ivity and inhibition of ventricular pacing.