INAPPROPRIATE SENSING OF ATRIAL STIMULI IN PATIENTS WITH 3RD-GENERATION DEFIBRILLATORS AND DDD PACEMAKERS

Although the problem of ICD sensing of paced ventricular stimuli has b een resolved by incorporation of VVI pacing into current ICDs, many pa tients require separate DDD pacemakers. We report a problematic PIM-IC D interaction: the inability to prevent sensing of paced atrial stimul i (''atrial sensing'') leading to double-counting in DDD-PM-requiring patients with transvenous (TV) ICDs with aggressive autogain sensing ( CPI Ventak(R) PRxII or III). Four of eight patients receiving both tra nsvenous DDD PMs and ICDs (CPI Endotak(R) lead, at the RV apex), had a trial sensing, leading to double counting, despite intraoperative test ing of multiple atrial locations with an active fixation lead. Five pa tients had a PRxII/III ICD, four with atrial sensing (80%), and three a PRx without atrial sensing. Patients with atrial sensing were not di stinguished by any clinical or device related variable. In patients wi th atrial sensing (all with heart block), the PM was programmed to VDD mode. No patient has received inappropriate therapy or failed to sens e VF in follow-up. In many patients with TV ICDs who require DDD pacin g, no atrial position can be found without ICD sensing of atrial stimu li. While in patients with heart block this problem can be circumvente d by programming to the VDD mode, in patients with sinus incompetence it may only be resolved by the combination ICD-DDD PM, currently in de velopment.