Occlusive devices used for the blocking of openings within the human body, particularly vaso-occlusive devices, are now well-known and widely accepted as specific treatments for a variety of maladies. Although we often discuss the invention herein as one dealing with the occlusion of blood vessel or aneurysm closure, the invention is not so limited and may be used in a variety of other sites in the human body, e.g., fallopian tubes, bile ducts, etc. All members of the class of vaso-occlusive devices are surgical implements that may be placed within the vasculature of the human body, typically by a catheter, either to block the flow of blood through the vessel making up that portion of the vasculature, or to fill an aneurysm which stems from such a vessel. One member of the class of widely used vaso-occlusive devices includes the helically wound wire coil. Fibers may be woven into or laid crosswise through the coil windings to provide an additional substrate for clot formation and tissue growth within the chosen site. Vaso-occlusive devices having such a structure are widely commercially available from, for instance, Target Therapeutics Inc.
One very early patent, U.S. Pat. No. 4,994,069, to Ritchart et al., describes such a vaso-occlusive coil. This vaso-occlusive device assumes a linear helical configuration when placed within a delivery catheter and a folded, convoluted configuration when relaxed after having been released from the delivery catheter. Ritchart et al. describes a number of secondary or relaxed configurations, each of which is suitable for a specific type of malady.
U.S. Pat. No. 5,226,911, to Chee et al., teaches a helical vaso-occlusive coil to which fibrous elements are attached in such a way that they will not be dislodged during use. The fibrous elements are placed on the coil to enhance the tendency of the coil assembly to cause clot formation and tissue growth.
U.S. Pat. No. 5,382,259, to Phelps et al., teaches a vaso-occlusive device having a braided covering produced of polymeric fibrous elements on the exterior of the device. A variety of biocompatible materials are shown as suitable for the braided exterior tubular member.
Although these patents and others describe vaso-occlusive devices having metallic substrates and fibrous additions, none of them show the combination of polymeric materials as described here nor their utility in promoting tissue growth. Specifically, none of the references discussed above suggest that the noted combination is able to produce neocapillary formation in the vasculature.