An externalized conductor occurs when the cable, or conductor, from inside the lead wears through the outer silicone insulation around the lead and appears outside the insulation body.

FORBES: St Jude Withdraws Older LV CRT Leads From Market

Optim insulation is a hybrid material that combines the biostability and flexibility of high-performance silicone rubber with the strength, tear resistance and abrasion resistance of polyurethane, to provide increased durability and flexibility.

FORBES: St Jude Withdraws Older LV CRT Leads From Market