A case series of anomalous high pacing lead impedances in normally functioning leads

Pacemakers and implantable cardioverter-defibrillator (ICD) cardiac leads are used for delivery of short direct current electrical pulses. Low-energy pulses in pacemakers provoke myocardial stimulation while high-energy pulses in ICDs are delivered for lethal arrhythmia termination. Pacing impedance measurements offer insight into implanted pacemaker system status; a decrease in impedance values may indicate a short circuit or insulation breach, while an increase may indicate a pacing lead fracture. Remote interrogation systems that capture automatic device diagnostic data, stored episode electrograms, and the presenting rhythm provide the clinician with information similar to that available at an office visit, allowing assessment of the appropriateness of device therapies and operation. We report a series of 3 cases of transient high lead impedance (42500 ohms) on remote checks with no other associated lead abnormalities, and no clinical events or abnormality seen on chest radiograph or office checks. These cases shared a common type of device manufacturer with a different type of lead manufacturer. Although ventricular pacing impedance was sporadically highly abnormal, device function was not impaired, and system revision was not necessary.