LAUSR

Modern implantable cardioverter defibrillators (ICD) employ dynamic sensing algorithms in order to protect against fine ventricular fibrillation without oversensing intrinsic activity. We present a patient with a Medtronic ICD who had inhibition of pacing and not inappropriate shocks due to T wave oversensing (TWOS) in both true bipolar (TB) and integrated bipolar (IB) sensing configurations. Rather than alternatives such as lead revision or programming to an unacceptably insensitive value, this was solved by exchanging for a Boston Scientific ICD. Although the literature suggests lead sensing configuration impacts TWOS, this case demonstrates ICD sensitivity algorithm may be a key determinant.