COMPARISON OF THRESHOLDS IN EPICARDIAL AND ENDOCARDIAL STIMULATION OF HUMAN HEART BY CHRONICALLY IMPLANTED PACEMAKER ELECTRODES

Thresholds of 31 epicardial and 24 endocardial pacemaker electrodes were measured 11 to 21 months after implantation. It was found that endocardial electrodes had only a slightly lower threshold than epicardial electrodes. When both types of electrodes are chronically implanted, differences between cathodal and anodal thresholds were also small. It is concluded that pacemaker units used with both types of electrodes should at least have an output of 15 Ma. into a 500 ohm load in order to avoid failure from high threshold. © 1969.