Immunity Mechanisms Involved in the Degradation of Polyurethane Leads

The examination by scanning electronic microscopy of polyurethane leads, implanted in rabbits, confirms the biodegradability of the product, and the optical microscopy performed on the blood-vessel and myocardium shows the immunity mechanisms set in action. Three months after implantation, we noticed an important epithelial reaction around the polyurethane lead and particles of the materials embedded in the vein wall. 13 months after implantation a large amount of fibrosis with plastic debris and calcification was present. With silicone and polyethylene there is no degradation of the products 4.5 months after implantation and only a modest tissue reaction without epithelial or pallisadic aspects.