The placement of a transvenous implantable cardioverter defibrillator (ICD) system through a single infraclavicular skin incision has been a surgical goal for years. The development of a new investigational model of ICD with substantially reduced dimensions (volume, 83 cm3; mass, 132 g) has made the one-incision approach a clinical reality. Between March and September 1993, 4 female and 19 male patients (mean age, 60 +/- 9.6 years; range, 46 to 73 years) underwent implantation of this device for the treatment of ventricular fibrillation (n = 14) or ventricular tachycardia (n = 9). One transvenous lead was placed in the right ventricular apex and another in the left subclavian vein. A subpectoral pocket was formed in the infraclavicular area from the same incision to house the ICD generator and, if necessary, the subcutaneous patch. The mean operation time (81.5 +/- 32.7 minutes; range, 54 to 195 minutes) was significantly shorter than that noted for a previous series made up of patients undergoing traditional transvenous ICD implantations. In 20 patients (87%), endovenous defibrillation without a subcutaneous patch successfully caused externally induced ventricular fibrillation to revert with a mean minimum energy output of 21.9 +/- 3.5 J (range, 12 to 24 J). Endovenous defibrillation was more successful when biphasic (n = 16/17 [94%]) shocks rather than monophasic shocks (n = 4/6 [67%]) were used. No mortality, morbidity, or surgical complications were observed. These results indicate that the one-incision approach and the small size of the ICD generator can substantially facilitate ICD implantation and result in a reduction in the surgical trauma, the operation time, and the amount of material implanted.