An incomplete pacemaker lead fracture causing inappropriate pacing inhibition due to oversensing of the minute ventilation sensor pulses.

Cardiac pacemakers using rate response technologies represent the effectiveness of increasing the heart rate and cardiac output during exercise. Minute ventilation (MV) sensors are popular and estimate rates using transthoracic impedance by emitting very low amperage short electrical current pulses between the pacemaker lead tip and pulse generator. We present a case of an incomplete pacemaker lead fracture developing inappropriate pacing inhibition due to oversensing caused by the electrical current emitted by the MV sensor. A permanent pacemaker replacement was performed, resulting in no further abnormal findings such as inappropriate pacing inhibition. <Learning objective: The minute ventilation (MV) sensor is estimated using the transthoracic impedance by emitting a very low amperage and short pulses of electrical current between the pacemaker lead tip and pulse generator. Therefore, if a fractured lead occurs, the voltage from the current pulses emitted for the MV sensor might be high enough to be oversensed as ventricular waves. We recommend that it is necessary to keep in mind the possibility of a fractured lead if oversensing of the thoracic impedance measurement current is observed.>.