Sensor-Driven Pacemaker Tachycardia During Chest Physiotherapy: The Hidden Accelerometer Sensor Response in a Leadless Pacemaker in the VDD Mode.

INTRODUCTION: Leadless pacemakers (LPM) provide ventricular pacing, atrio-ventricular (AV) synchrony and rate response. BACKGROUND: In the VDD mode, the single-chamber LPM is capable of atrial sensing with additional accelerometer activity sensing rate response. METHODS AND RESULTS: An 85-year-old man with tachy-bradycardia received a Micra AV2 (Medtronic Inc). During chest physiotherapy, pulse rate increased to over 100 bpm during chest percussion when performed on the left side. This was due to VDD mode switching to VVIR pacing when the accelerometer sensor rate exceeded the atrial rate. Inactivation of mode switching prevented rate acceleration. CONCLUSION: Chest physiotherapy caused unexpected rate increase in LPM even in VDD mode.