A method for estimating endocardial electrode stability

Assessment of cardiac pacing electrode stability following implantation is of major importance. We describe a method of testing electrode stability using a provocative test. The method includes synchronized electrical pacing of the left phrenic nerve by an especially designed external pacemaker. A positive response is abrupt, a diaphragmatic contraction, which in turn induces an abrupt heart movement in its diastole, its relaxation phase. Fifty-six various endocardial electrodes were tested in this fashion. Seven electrodes, one with flange tip, two tined, and four had no fixation dislodged after this pacing test. Insignificant elevation of acute ventricular pacing threshold was observed. While this method appears to be advantageous, additional clinical data is necessary.