Therapeutic Research

Abstract

Introduction: The Micra transcatheter pacing system（Micra TPS; Medtronic, Minneapolis, MN, US）, a type of leadless pacemaker, is a novel technology in recent years as a treatment for bradycardia. Moreover, atrioventricular synchronous pacing using a ventricular accelerometer of the Micra TPS（Micra AVTM） is now available for patients with atrioventricular block. Micra is a leadless pacemaker implanted in the right ventricle and use accelerometer –based, sensing the flow of blood as a mechanically signal associated with atrial contraction. Micra AV can do physiological pacing because it synchronizes with A4 signal generated by atrial contraction. Methods: We studied the atrioventricular synchronization rate of the cases of Micra AV implanted in our hospital. We adjusted atrioventricular synchronization immediately after implanted Micra AV, and synchronization rate assessed before discharge. Results: The patients were 9 men and women aged 84±6.5 years（mean±SD） who had disease bradycardia –tachycardia syndrome and paroxysmal or permanent third–degree AV block. atrioventricular synchronization rate was 83.2±12.9％（mean±SD）. 7 patients was high synchronization rates（≧80％） and 2 patients was low synchronization rates（＜80％）. A4 signal were clarity and high in high synchronization rates cases. Discussion: A4 signal sensing may be most important key of high synchronization rate. However, there are reports that A4 signal disappears because does not cause blood flow of atrial contraction by atrial arrhythmia, similar findings were obtained in low synchronization rates cases. Other, it was reported ischemic heart disease and cardiac surgery may have something to do with A4, CABG postoperative patients have low A4. So, indicated diseases and history must be considered aiming for a stable synchronization rate. There are reports that synchronization rates of Micra AV is fluctuate on body position and activity. In view of this, the programming optimization is necessity for keeping high synchronization on periodic visits and follow up. Conclusions: We revealed that A4 signal sensing is impor tant key of high synchronization rate of Micra AV.