Impedance changes on defibrillation coils after atrial fibrillation ablation: lead damage or electromechanical interference?

Fluctuation of impedance on defibrillator leads is highly suggestive of lead failure. A drop in impedance is associated with insulation defects while high impedance is suggestive of lead fracture. In this case report, we described a patient where electromagnetic interference from radiofrequency ablation near the site of superior vena cava coil caused the sensed impedance to fluctuate without uneventful outcomes and we discussed the possible mechanism. Both electromagnetic interference and defibrillator lead insulation defect can result in low threshold and inappropriate shocks. Sometimes electromagnetic interference may result in physical damage of the implanted system and may result in subsequent fluctuations in impedance. Awareness of electromagnetic interference that can cause fluctuating impedance without structural damage can help in making appropriate diagnosis and may avoid unnecessary procedures.