The combined transvenous implantation of cardioverter defibrillators and permanent pacemakers.

We developed criteria for implantation and programming of permanent endocardial pacemakers in patients with a nonthoracotomy ICD system. These criteria were prospectively used in 10 patients who recieved an ICD prior to (n = 5) or following (n = 5) implantation of a dual chamber (n = 6) or ventricular (n = 4) pacemaker with a unipolar (n = 4) or bipolar (n = 6) lead configuration. All patients were tested for interactions or malfunctions. Undersensing of ventricular fibrillation by the atrial sense amplifier and inadequate atrial pacing occurred in one patient with a unipolar dual chamber system programmed to AAIR but didn't impair ICD sensing. Transient or permanent loss of capture or sensing of the pacemaker was not observed after ICD shocks with the output programmed to double pulse width and voltage of stimulation threshold and the sensitivity to 50% of the detected R wave. One episode of transient reprogramming occurred without clinical consequences. One unipolar ventricular pacemaker lead had to be exchanged against a bipolar lead because of oversensing of the pacing artifact by the ICD. There was no failure of an ICD to detect ventricular arrhythmias due to inadequate pacemaker activity. During a follow-up period of 21 +/- 11 months, a total of 78 ventricular arrhythmias were effectively treated in six patients. Thus, a combined use of transvenous ICD and pacemaker is possible despite the close vicinity of pacing and defibrillations leads. Optimized programming different to the common settings is required. As interactions occurred only in unipolar pacemaker leads bipolar systems should be used in these patients.