Abstract
Since 1964, 83 epicardial leads were implanted in 39 patients. Sensing failures occured in 3 of them. The sensing failures were classified into 3 groupes in terms of their etiologies, listed as follows: 1, The low amplitude of R wave to be sensed. 2, Inappropriate electrical connection between the lead and myocardium. 3, Electromechanical failure of the pacer unit. Canine experiments were performed to elucidate the best portion of the heart to be implanted as well as the most appropriate method for implantation with regard to sensing the sinus beats. It was found that, improper implantation resulted in a marked decrease in the amplitude of R wave to.be senced although the amplitude showed little difference according to the sites of implantation.
