“…In vitro bending tests 8 show that small changes in pacing impedance or DCR are sensitive for conductor fracture, 2 but clinical lead monitoring alerts that measure oversensing are more sensitive than those that measure impedance. 3 , 4 , 5 , 6 , 10 , 11 , 12 Usually, bending tests are performed on short conductor segments, rather than on complete leads, continued to complete fracture so that the onset of partial fracture is not determined, and performed in air so that fracture-induced signals cannot be recorded. 8 By testing complete leads connected to an ICD generator in saline, we determined the sequences of EGM and DCR or impedance changes and correlated them, both with each other and with structural changes in developing fractures.…”