Not Applicable
Not Applicable
1. Field of the Invention
The present invention is directed to implantable medical devices, such as stents, grafts, and vena-cava filters among others. Specifically, the present invention is directed to a medical device, particularly a stent, which includes in its construction or is at least partially constructed from a magnetic material, or has magnetic properties such as may be provided by a magnetic coating or other means.
2. Description of the Related Art
Stents for transluminal implantation are well known. They are generally comprised of metallic supports which are inserted into a part of the human body such as bile ducts, the urinary system, the digestive tube and notably by percutaneous route inside the blood vessels, usually the arteries in which case they are typically termed vascular stents. Stents are usually generally cylindrical and are constructed and arranged to expand radially once in position within the body. They are usually inserted while they have a first relatively small diameter and implanted in a desired area, for example inside a vessel, then the stent is expanded in situ until it reaches a second diameter larger than the first diameter.
A balloon associated with the catheter is usually used to provide the necessary interior radial force to the stent to cause it to expand radially. An example of a balloon expandable stent is shown in U.S. Pat. No. 4,733,665 to Palmaz, which issued Mar. 29, 1988, and discloses a number of stent configurations for implantation with the aid of a catheter. The catheter includes an arrangement wherein a balloon inside the stent is inflated to expand the stent by plastically deforming it, after positioning it within a blood vessel.
Self-expanding stents are also known which can expand from a first diameter to a larger second diameter without the use of a means for applying an interior radial force, such as a balloon, to them. A type of self-expanding stent is described in U.S. Pat. No. 4,503,569 to Dotter which issued Mar. 12, 1985, and discloses a shape memory stent which expands to an implanted configuration with a change in temperature. Other types of self-expanding stents not made of shape memory material are also known.
The use of magnets to promote healing and reduce pain is well known in the medical profession. There have been many studies in which it has been found that the use of a magnetic field can assist in improve post operative healing. Additionally, there have been many studies in which the use of a magnetic field helps to alleviate pain due to muscle strains, tennis elbows, sore muscles, lower back pain, arthritis and the like. For example a recent study entitled Magnetic Bio-stimulation in Painful Diabetic Peripheral Neuropathy: a Novel Interventionxe2x80x94a Randomized, Double-placebo Crossover Study (American Journal of Pain Management Vol. 9 No. 1 January 1999 pgs. 8-17) illustrated the benefits of magnets in assisting in pain control and healing.
While there have been many different theories advanced as to why magnetic therapy works, it is still not clearly understood exactly how magnetic therapy aids in healing and in reducing pain. However, many devices have been developed to practice magnetic therapy. One such magnet device for therapeutic use is disclosed in U.S. Pat. No. 4,549,532, which describes a permanent magnet sheet having alternating poles for applying a magnetic field to portions of the body for therapeutic purposes. Other devices which are magnetic or include magnetic properties are described in U.S. Pat. Nos. 6,126,589; 6,066,088; 5,782,743; 5,304,111; and 5,336,498. Other medical devices which utilize magnets and magnetic fields are known.
While many prior devices which utilize magnets for improving healing are used or applied to the exterior of a body or portion thereof, there remains a need to provide for implantable medical devices which are intended to repair or support surrounding tissues with magnetic properties. As such there is a need to provide a stent with magnetic properties in order to encourage healing of a potentially damaged or weakened vessel.
The entire content of all of the patents listed within the present patent application are incorporated herein by reference.
In light of the above, the present invention is directed to the internal application of magnetic effects by constructing a medical device, such as a stent or a portion thereof, with magnetic materials. As a result, the present invention is directed to a dual function medical device. For example, in the case of a stent, the invention provides support to a vessel or lumen, as well as providing a vessel and/or legion site with the beneficial healing effects of magnetism via the magnetic materials of the stent.
As indicated above, the present invention is directed to implantable medical devices which are constructed at least partially from magnetic materials. In the case of a stent, the stent may be entirely composed of magnetic material, or may include strips of magnetic material intertwined with conventional stent materials.
In at least one embodiment of the invention, at least the magnetic materials of the stent may be coated with a biocompatible material such as gold.
In at least one embodiment at least a portion of the stent is at least partially coated with a magnetic substance.
In at least one embodiment of the invention the various struts and members of the stent may be at least partially porous or hollow, wherein the pores or hollow chambers may be filled with a magnetic material.
In at least one embodiment of the invention the magnetic material is temporarily magnetic.
In at least one embodiment of the invention the magnetic material is permanently magnetic.
These and other more detailed and specific objectives and an understanding of the invention will become apparent from a consideration of the following Detailed Description of the Invention in view of the Drawings.