Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-02-19
2001-05-08
Yasko, John D. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S500000
Reexamination Certificate
active
06228072
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to surgical device design and fabrication and, more particularly, to a shaft for medical catheters.
2. Background of the Invention
Medical catheters, such as balloon catheters, have been proven efficacious in treating a wide variety of blood vessel disorders. Moreover, these types of catheters have permitted clinicians to treat disorders with minimally invasive procedures that, in the past, would have required complex and perhaps life threatening surgeries. For example, balloon angioplasty is now a common procedure to alleviate stenotic lesions (i.e., clogged arteries) in blood vessels, thereby reducing the need for heart bypass operations.
Previously known catheters are of complex construction, requiring expensive manufacturing steps and construction of great precision to navigate the tortuous pathways of a vessel network. For instance, when a catheter provides inflation fluid to a balloon, a small notch is typically provided in the catheter tube to allow fluid to pass from a lumen within the tube to the balloon. The conventional method for manufacturing this notch is with a laser, which is expensive and often cannot be done in-house. Further, use of a laser creates a heat-affected zone which can lead to fracture of the notch. Moreover, the heat from the laser may cause deformation of the material. This is especially problematic when a straight catheter made of a nickel-titanium alloy is desired. Because the properties of NiTi alloys are extremely temperature sensitive, laser notching may cause buckling or unwanted curvature in the material. Accordingly, there is a need for a notch-forming process which will not cause damage to the material.
Further, profile is often a concern for catheters because of the small space in which the catheters will be inserted. In addition, because catheters must be passed through a tortuous blood vessel network to reach the intended treatment site, it is desirable that the catheters be substantially frictionless to reduce harmful contact with blood vessel walls. Catheters therefore are generally provided with a coating that will increase lubricity of the catheter. These coatings add additional, undesired size to the catheter. Thus, there is a need for a substantially frictionless catheter surface which does not add significant profile to a catheter tube.
In navigating the pathways of a vessel network, a radiopaque marker is often necessary to identify a specified location on the catheter. Such markers are typically placed on the catheter tube near the location of a distal balloon. However, in medical devices employing aspiration catheters and the like, visibility problems often arise with such markers because they are typically made small in order to allow the aspiration catheter to be passed over the marker as it extends towards the distal balloon. Accordingly, there is a need for balloon catheters having markers which can better identify the location of a balloon while inside a blood vessel.
SUMMARY OF THE INVENTION
The present invention addresses the needs raised above by providing several improvements in the design of a shaft for medical catheters. In one aspect, a small notch is fabricated into a catheter tube by a nonlaser process such as electric discharge machining (EDM) or mechanical grinding. This notch in the catheter tube is necessary for fluid communication between the catheter lumen and a balloon or other element in communication with the tube. Use of a nonlaser process reduces the costs of fabrication while ensuring a high degree of structural integrity.
In another aspect of the present invention, a method is provided to produce a thinner coating on a catheter shaft to reduce friction with vessel walls. To maintain a surface with a low friction coefficient while keeping the profile of the catheter low, the catheter is sputter coated with Teflon or similar material to produce a nonuniform coating. This nonuniform coating may extend 360 degrees around the catheter tube, and may even provide a coating of less than 360 degrees while still maintaining good lubricity.
In yet another aspect, a catheter wire or tube is provided with a radiopaque marker which is more visible and is more effective at identifying the location of a balloon on the catheter. The marker is moved closer to a distal balloon by placing it within an adhesive taper adjacent the balloon. By placing the marker in the taper, the marker can be made larger and more visible without obstructing the placement of an aspiration catheter or other type of catheter over the catheter wire or tube. Specifically, the marker in being placed inside the taper and closer to the balloon can act as a stopper to the aspiration catheter and prevent damage to the balloon.
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Leguidleguid Roy
Muni Ketan P.
Omaleki Samuel L.
Knobbe Martens Olson & Bear LLP
PercuSurge, Inc.
Yasko John D.
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