B-PO03-015 A CONFUSING TALE OF TWO LEADS

Abstract

Presenting CRT-D problems do not always indicate the underlying issue. To demonstrate that thorough device interrogations and defibrillation threshold testing (DFTs) are critical to diagnose and treat problems with CRT-D systems. A 33-year-old female was referred for a revision of her CRT-D system. Her original system was implanted for compete heart block and later upgraded to a CRT-D system with an epicardial LV lead after she was diagnosed with non-ischemic cardiomyopathy and VT. A recent device interrogation demonstrated R-waves of 1 mV down from 20 mV prior and therefore she was scheduled for a system revision. In the EP lab, a thorough device interrogation was performed and a slow escape rhythm was demonstrated with R waves between 15-20 mV. The prior 1 mV sensing was felt to be inaccurate as she had become pacemaker dependent, and had no sensed events (at VVI 40) for several months. We then performed DFTs given her history of VT and questions of inadequate RV sensing. Two inductions were performed and her device adequately sensed VF waves that measured 8-10 mV and her device successfully restored sinus rhythm. After DFTs, the shock impedance of the RV lead was noted to be >200 ohms, the LV lead was not capturing at maximum outputs, and the LV lead impedance was >3000 ohms. The epicardial LV lead was a unipolar lead with one pacing configuration from the LV tip to RV coil. We concluded the RV defibrillator lead was damaged by DFTs (although still able to deliver a shock) and LV lead was nonfunctional either because it was also damaged or because the pacing configuration included the RV lead. The patient underwent an extraction and re-implant of a new RV defibrillator lead. Intraprocedural testing demonstrated adequate function of the LV unipolar lead with appropriate sensing, impedance, and capture thresholds with the new RV lead. This patient was referred for system revision for inadequate sensing on her ICD lead, however, after DFTs we determined that she had suffered a conductor fracture in the lead, which also raised questions about her unipolar epicardial LV lead. Revision of the RV lead, although not for the original problem prompting referral, fixed her system.