Rise in ICD Shock Impedance: Lead Fracture or Death?

Abstract

Postmortem analysis of ICDs allows tracking of lead impedance changes, which correlate with the day of death. The rise in postmortem impedances should not be interpreted as contributing to the mode of death.

Postmortem ICD interrogation in mode of death classification

“…We identified 163 citations of which 22 studies met the inclusion criteria (Figure and Table ) . The studies were undertaken between 1982 and 2015 with 23,600 participants.…”

“…ICD interrogation was performed in all deaths in three studies . In nine other studies, the use of device interrogation ranged from 39% to 89% of total deaths or 20–100% of sudden deaths (Table ) . Three studies did not report the precise number of postmortem recordings obtained .…”

Abrupt increase in impedance measurements as detected via remote monitoring: What is the cause?

“…We performed an exhaustive literature search regarding impedance changes immediately before death and found only 1 other such report, 1 although there is a modest body of work describing postmortem impedance changes in animal models. We found 1 reference to pacing impedance increase during dehydration in a living patient, 2 and whole body bioimpedance spectroscopy has been reported to be a reliable method of assessing hydration status in children 3 .…”

Implantable Cardioverter‐Defibrillators: Is There Life after Death?

“…Apart from stored electrograms of arrhythmias responsible for death, data are lacking about changes in other ICD parameters recorded in the hours or days after death. A recent paper investigated the changes in lead impedances at the time of death and afterwards . In 37 Biotronik ICDs (Biotronik Gmbh, Berlin, Germany) there was a significant immediate and predictable rise in impedance (unrelated to cooling) in the pacing and shock leads after death, not related to lead malfunction.…”

“…A recent paper investigated the changes in lead impedances at the time of death and afterwards. 16 In 37 Biotronik ICDs (Biotronik Gmbh, Berlin, Germany) there was a significant immediate and predictable rise in impedance (unrelated to cooling) in the pacing and shock leads after death, not related to lead malfunction. Further investigations are warranted to determine whether these findings can be extrapolated to devices of other manufacturers, to pacemakers, and to larger groups of patients.…”