Implantable product with improved aqueous interface characteristics and method for making and using same

Abstract

An implantable medical device including a porous membrane that is treated with a hydrophilic substance to obtain rapid optimum visualization using technology for viewing inside of a mammalian body. These technologies include ultrasound echocardiography and video imaging such as that used during laparoscopic procedures.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 159,836 filed May 31, 2002.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to implantable medical devices and more particularly to medical devices that are designed to be surgically or endoluminally placed in a body. [0004] 2. Description of Related Art [0005] Medical devices designed to be introduced through catheter-based delivery systems or through trocars are often deployed using various remote visualization techniques, such as x-ray imaging, fluoroscopy, ultrasound, and / or video imaging. [0006] It has been determined that devices made from certain microporous polymers, such as expanded polytetrafluoroethylene (PTFE), sometimes are difficult to properly visualize using certain remote visualization techniques because air trapped in the microporous polymer can distort remote images. Most porous materials will eve...

AI Technical Summary

Benefits of technology

[0019] The present invention employs treatment of an implantable medical device, comprising a microporous membrane supported by a frame, that allows the device to be rapidly and accurately visualized by ultrasound and video imaging, and renders the device transparent under direct visualization. The present invention eliminates air-interference issues with porous membrane devices, such as those incorporating expanded PTFE, by modifying the porous membrane with a dried hydrophilic substance, such as polyvinyl alcohol (PVA), to allow the membrane to rapidly displace air with liquid once introduced into the body or otherwise contacted with an aqueous liquid. The presence of dried hydrophilic substance on and / or in the pores of the membrane vastly increases the rate at which air is displaced by aqueous liquids and improves the rapid and precise visualization of the device.

[0020] The preferred device of the present invention comprises an expandable frame attached to a porous expanded PTFE membrane that includes a cross-linked PVA material bound to the membrane. This construction is suitable for use with a wide variety of remotely deployed devices, such as septal and other occlusion devices, embolic filters, certain stent-graft devices, implantable sheets, and the like. In addition to allowing for very rapid accurate visualization of the implanted device, the present invention is believed to also provide a number of other benefits, including improved biological performance and better ingrowth.

[0021] Another benefit of the present invention is its ability to absorb aqueous solution, which may contribute to a significant decrease in the abrasion type injuries seen when membranes come in contact with tissue. In those instances where a membrane that is impervious to fluid transmission is required, a barrier membrane can be inserted between layers of expanded PTFE, thus allowing ultrasound transmission and ingrowth.

Problems solved by technology

It has been determined that devices made from certain microporous polymers, such as expanded polytetrafluoroethylene (PTFE), sometimes are difficult to properly visualize using certain remote visualization techniques because air trapped in the microporous polymer can distort remote images.

Most porous materials will eventually wet-out with body fluids following implantation, although this process may take time.

In the case of expanded PTFE, its hydrophobic nature can vastly slow the process of replacing air with fluid following implantation—which can lead to poor initial visualization following implantation.

As use of this material has increased, it has become evident that these devices often do not provide optimal initial visual clarity under ultrasound, video imaging, and direct visualization.

Ultrasonic imaging is a somewhat vexing problem for implantable porous materials.

As a result, the presence of air in an implantable membrane introduces a disruptive layer that will interfere with normal ultrasound wave transmission.

For some applications, this process of slow wetting-out may be undesirable.

Devices such as fluoroscopes and x-rays can provide such visualization, but the harmful radiation these devices deliver to patients and medical personnel make them less desirable for daily use.

To date, no entirely suitable method of instantly ultrasonically visualizing a device incorporating a porous membrane has yet been developed.

For instance, in Japanese Patent 10-244611 to Oga it is recognized that expanded PTFE implantable sheet material has a number of problems, including that: it cannot be seen through; it reflects light, causing glare problems for surgical staff; and it cannot be effectively probed with ultrasound.

While this approach may solve visualization problems, it presents a number of other problems, including vastly increased manufacturing, packaging, shipping, and handling problems while dealing with a pre-wetted material.

In PCT Patent Application WO 96 / 40305 to Hubbard, it is again recognized that expanded PTFE cannot be seen through, it reflects light, and it is not suitable for ultrasound imaging.

Again, this concept requires increased expense and effort in dealing with the manufacturing, packaging, and handling of a “wet” product.

However, particularly with regard to endoscopically deployed devices that mount porous membranes on some form of support frame, none of these previous concepts has taught or suggested an ideal solution to aid in the instant visualization of an implanted device that is highly effective, simple to implement, and does not burden the manufacturing, packaging, shipping, or handling of the implantable device.

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