Epidural Lead Fracture Caused by Material Processing Fault

Abstract

Fracture of the epidural lead (Pisces Quad 3487) is documented in four out of eight patients with an implanted Itrel pacing system for treatment of peripheral vascular disease. In two patients, lead fracture was established during x-ray fluoroscopy. In the remaining two patients, x-ray examination did not reveal any fracture, due to proximity of the fragments. Microscopic examination of the extracted lead, however, confirmed lead fracture, as well as the presence of tissue fluid and thrombus between the two ends of the spiral shaped lead, but no insulation defect was observed. A cross-sectional area on the fracture line of the broken lead was examined using scanning electron microscopy. It was found, by tracing the radial marks to their point of convergence, that the initial microcrack started from a large inclusion of the calcium-silicon type at the lead surface. The initial microcrack was propagated by the fatigue mechanism. The presence of a large inclusion at the surface suggests that the main cause of the failure of the investigated epidural leads could be improper fabrication of the material. The high incidence of epidural lead fracture in our group suggests that this complication should be considered as a possible cause of epidural spinal electrical stimulation pacing system dysfunction.