Therapeutic Research

Abstract

In this report, we describe a case of suspected dislodgement after implantation of a leadless pacemaker（Medtronic MICRA transcatheter pacing system）. The patient was 86 years old, male. The patient was referred from his previous doctor for heart failure due to complete atrioventricular block（CAVB）.Preparation left subclavian venography showed venous obstruction, and a leadless pacemaker was implanted. The data on the morning after implantation showed mild improvement over the time of implantation. However, after the rehabilitation in the evening, pacing failure appeared on the monitoring ECG. Pacemaker check was performed and the pacing threshold was increased to 2.63 V/1.0 msec, sensing could not be measured, and impedance was ＞2500Ω, all data indicated deterioration. Chest X –ray showed no change in position compared to the time of implantation, and there was no evidence of leadless pacemaker dislodgement. The pacing output was changed to 5.0 V/1.0 msec and the policy was to observe the progress. On the third day after implantation, a mild improvement in threshold was observed, and furthermore, both sensing and impedance were measured. The patient was checked until day 7 after implantation, data stability was confirmed, and the patient was discharged on day 8 after implantation. A Case Report by Niels, et al. in 2016 found worsening of pacing threshold and impedance at 2 weeks after implantation, and reported that micro dislocation may occur because of tine fixation. The same micro dislocation occurred in our case, which may have caused the pacing threshold and impedance to increase. In this study, we experienced a case of pacing threshold elevation after leadless pacemaker implantation with only follow –up and improved data.