Initial clinical experience with a dual lead endocardial defibrillation system with atrial pace/sense capability. United States and Canada Enguard Investigations.

Ninety-three patients underwent implants of the Telectronics Model 4211 ICD attached to the Enguard PFX endocardial defibrillation lead system. Eighty-one males and 12 females ranging in age from 25-85 years (mean = 64). Coronary disease was the substrate in the majority (88%); mean left ventricular ejection fraction was 30%. VT was present in 66%, VF in 22%, and both in 7%. Three lead configurations were used in the study: ventriculo-atrial (U1, 86%); bidirectional (B2, 12%); and ventricular to patch (U2, 2%). Mean RV pacing thresholds were 0.46 V pre- and 0.54 V posttesting, with no significant differences between the two. Mean R wave voltage was 11.05 mV pre- and 11.72 mV posttesting, also not significantly different. A subgroup of 13 patients had mean atrial pacing thresholds of 0.59 V at 0.5 msec pulse width, with mean P waves of 4.01 mV. Mean defibrillation threshold for the entire group was 10.6 J using biphasic waveforms. Defibrillation thresholds by configuration were: 399 V (U1); 475 V (U2); and 350 V (B2). All patients but one had thresholds < 550 V in at least one configuration. The 4211/Enguard system was implanted without (86%) or with (14%) a subcutaneous patch electrode. Early postoperative findings related to the ICD system include: one device circuit failure, one early lead dislodgement, and one pacing exist block.(ABSTRACT TRUNCATED AT 250 WORDS)