The significance of electrode surface area and stimulating thresholds in permanent cardiac pacing.

This paper reports a long-term clinical study of evolving chronic thresholds of cardiac stimulation in patients with implanted pacemakers and two types of permanent prevenous unipolar pacing leads. A comprehensive collection of threshold measurements is presented and analyzed. These data were accumulated over a period of more than 4 years by measuring stimulation thresholds at each of five stimulus pulse durations ranging from 0.5 to 2.5 msec. Measurements were made at initial implantation and at first (21 month) and second (42 month) reimplantations.