Electrical Failure of an ICD Lead due to a Presumed Insulation Defect Only Diagnosed by a Maximum Output Shock

Abstract

A 55-year-old male patient presented after a single shock caused by oversensing of isolated nonphysiologic signals on both the distal HV and pace-sense channels. No other abnormalities were found. He subsequently returned complaining of device "vibration" and his St. Jude implantable defibrillator (ICD; St. Jude Medical, St. Paul, MN, USA) was found to be in VVI backup mode and could not be interrogated. Direct testing in the electrophysiology lab showed normal lead impedances and thresholds with an inability to reproduce the abnormal signals. Detailed cine fluoroscopy of the leads found no abnormalities. A new ICD was connected and successfully delivered a 20-joule shock but failed to deliver a maximum output (39-joule) shock. The new ICD was again found to be in backup mode. A new Endotak Reliance G lead (Boston Scientific, Natick, MA, USA) was implanted and a maximum-output shock was successful using a new Fortify DR ICD. This case likely represents a Durata lead insulation defect in the form of an inside-out abrasion under the distal HV coil. Increased awareness of this defect is warranted, particularly since routine interrogation and submaximum-output shocks may fail to detect the problem.

Performance of Lead Integrity Alert to Assist in the Clinical Diagnosis of Implantable Cardioverter Defibrillator Lead Failures

“…Two case reports describe simultaneous spikes on near-field and far-field EGMs in inside-out, cable-coil short circuits of St. Jude leads. 18,19 Our data indicate that such EGMs are common in failures of St. Jude leads, but we lack returned-product analysis data to confirm the failure mechanism. However, 1 case ( Figure 5B, impedance trends) showed simultaneous drops in both pacing and shock impedance, coincident with simultaneous spiky EGMs on near-field and far-field EGMs ( Figure 5B, impedance trends), suggesting cable-coil abrasion.…”

Defibrillator Threshold Testing at Generator Replacement: Is it Time to Abandon the Practice?

“…“Silent lead malfunction” is a phenomenon observed uniquely at generator replacement . It was a universal finding in the reported cases that lead integrity issues were undetectable by routine testing and fluoroscopy.…”

Implantable Cardioverter-Defibrillator Leads

“…Contact between the proximal coil and cable to the distal coil shorts the high-voltage conductors, which prevents successful defibrillation. [18][19][20] Contact of the ring electrode cable with either shock coil results in sensing abnormalities. 20,21 Lead Failure: Clinical Presentation and Diagnostic Tools…”