Pacing lead insulator
First Claim
1. A method for making a flexible pacing lead insulator having reduced susceptability to stress cracking when implanted in vivo for an extended period of time, the method comprising the steps of (a) providing an insulator body of a first, flexible polyurethane elastomer, said elastomer having a first concentration of ether linkages;
- and (b) applying a thin layer of a second polyurethane elastomer onto said insulator body, said second elastomer having a second, lower concentration of ether linkages, said second elestomer selected from the group consisting of a polyether urethane elastomer having a hardness at least about 90A on the Shore A scale and a substantially ether-free biostable polyurethane elastomer.
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Abstract
The present invention provides resistance to degradation from environmental stress cracking (ESC) and metal ion induced oxidation (MIO) for implantable, flexible pacing lead insulators having a body of polyether polyurethane elastomer material. A thin layer of a second polyurethane elastomer is applied as an overcoat to the lead insulator body. The second polyurethane is more resistant to ESC and MIO than the elastomer comprising the body of the insulator. Because ESC and MIO are surface phenomina, only a thin layer of the second material is required and the mechanical properties of the base material will determine the overall mechanical properties of the lead insulator.
19 Citations
6 Claims
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1. A method for making a flexible pacing lead insulator having reduced susceptability to stress cracking when implanted in vivo for an extended period of time, the method comprising the steps of (a) providing an insulator body of a first, flexible polyurethane elastomer, said elastomer having a first concentration of ether linkages;
- and (b) applying a thin layer of a second polyurethane elastomer onto said insulator body, said second elastomer having a second, lower concentration of ether linkages, said second elestomer selected from the group consisting of a polyether urethane elastomer having a hardness at least about 90A on the Shore A scale and a substantially ether-free biostable polyurethane elastomer.
- View Dependent Claims (2, 3, 4, 5, 6)
Specification