Use of an electronic apex locator on a cardiac pacemaker patient.

Modern cardiac pacemakers are complex and heterogenous devices. The potential effect of electrically powered instruments on a patient's pacemaker function must be carefully evaluated before treatment. Interference with the pacemaker's function by the instrument depends on the specific type of pacemaker placed and the patient's dependence on it. A case is presented in which an electronic apex locator was used on a patient with a pacemaker, despite the manufacturer's written warning to the contrary. The patient's cardiologist was consulted before treatment.