Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
2001-11-21
2004-04-06
Truong, Kevin T. (Department: 3731)
Surgery
Instruments
Internal pressure applicator
C604S109000
Reexamination Certificate
active
06716230
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an attachment for use with an electromechanical driver device, and more specifically to a vascular expander device which is insertable, expandable, collapsible, and removable within and from a vascular, lumen, or similar vessel by means of a remote electromechanical driver device.
2. Description of the Prior Art
Upon identification of a stricture and/or stenosis in an artery, gastrointestinal tract, bowel, or other vessel of the body (for another important example, the bile duct) several treatment actions may be selected. Surgical intervention may include fully invasive procedures such as bypasses in which supplemental vessels are transplanted from other regions of the body, or in less frequent circumstances, artificial supplemental structures are implanted. This fully invasive procedure often requires significant hospitalization and tremendous rehabilitation. For these reasons, it has been a goal of the industry to minimize the number of instances in which these procedures are performed to the barest minimum. The less invasive surgical intervention, which has become more desirable, is one in which a device is inserted into the segment of the vessel which has narrowed, and to inflate the device within the segment until the passage through the vessel has been expanded to a more acceptable diameter. This procedure has been widely accepted and is only untenable in situations where the stenosis has occurred to such a great extent that the device cannot be inserted. Target tissues for such procedures, as mentioned above, include cardiovascular arteries which have sclerosed, peripheral vascular arteries which have sclerosed, bowel tissue which has narrowed due to scarring or other narrowing event, to an extent that such sclerosing or narrowing inhibits the proper flow of digestion, and normal use of any other soft tissue vessel which has sufficient elasticity to expand.
While the methodological innovation of expanding a structure within a stenosed vessel to increase flow therethrough to a more desirable level is one of the great advances in medicine of the last few decades, the instruments utilized in the execution of these procedures have lagged substantially behind the development curve. The traditional instrument for such a procedure, for example, a dilation balloon catheter for an angioplasty, is a long flexible tube having a selectively expandable volume disposed in the tip of the device. This tube having the expandable volume in its tip is directed through the femoral artery, the aorta, and into the heart itself. From the heart, it is directed into the partially blocked vessel. Once the tip of the device is disposed in the narrowed channel, a fluid (usually saline) is advanced into the flexible expanding volume to cause it to inflate. The inflating balloon presses against the walls of the vessel, causing them to expand outwardly. This process is continued until the vessel is enlarged to the point that the physician feels that the flow through it will be sufficient to alleviate the symptoms and potential for damage.
One of the most important drawbacks of the balloon catheter design is that the means for inflating the volume, and the manner in which the volume is inflated, completely blocks the flow of fluids through the vessel during the procedure. This failure is inherent in the design by virtue of the fact that the balloon must occlude the vessel in order to apply the pressure to the walls. A few alternative designs have been proposed in the art which provide a minimal solution to the problem by offering a number of cannulae, or narrow and rigid pass through holes, formed in the balloon itself, for permitting a small amount of fluid to flow when the balloon is fully inflated.
This attempted solution further highlights (and exacerbates) the other important failure of balloon type devices. This failure relates to the gathering of information about the expansion of the vessel walls. More particularly, one of the important measurements involved with any vessel expansion is the change in diameter, which is attained at a given internal pressure of the balloon. The relationship of pressure and diameter is inherently imprecise as vessel tissue varies in elasticity across the spectrum of potential patients as well as the degree of expansion or vessel narrowing which has already taken place (for example, a second or third angioplasty might proceed with a completely different pressure to diameter profile from that of a first time procedure). The inclusion of narrow passages through the expanding volume, especially in the case of a balloon having a cannulated structure, results in a very unreliable interior pressure to diameter relationship.
Unfortunately, it is also not always the case that the one time expansion of the vessel (during the surgical intervention) continues to remain effective over a long period. The stenosis of the vessel often continues, and the flow through the treated area may drop again to a level requiring additional intervention. As repeated expansion of the vessel stresses the tissue, and has been linked to the formation of aneurysms, it has been found necessary to install a permanent structural element into the vessel. These structural elements, which are generally referred to as stents, are generally tubular in shape, but are formed in a variety of different manners, including solid cylinders, meshes, fabrics, etc. The introduction of a stent into a patient usually follows a traditional angioplasty procedure, during which the vessel is expanded to the necessary diameter for the stent to be inserted. The remote installation of a stent is difficult, but several designs have been offered in which the stent is delivered in a collapsed form, and is then irreversibly expanded into position by means incorporated into the insertion tube. The diameter of a specific stent is, therefore, predetermined, and the diameter of the stent selected must be picked correctly.
It has been found, however, that over time, the stent is incorporated by the body, into the tissue wall of the vessel. Continued stenosis of the vessel around, and/or through the stent, presents an immediately understandable problem for continued treatment, i.e., the stent is a rigid metal structure which will prevent an angioplasty procedure from being able to expand the vessel (the balloon will expand against the stent, and the stent will remain undeflected).
Removal of a stent which has already been incorporated by the body is a considerable problem. Techniques of sheering off the tissue which has built up on and around the inside of the stent have been provided in the art, however, these generally include a rotating blade within the vessel. The risks of particulate matter becoming dislodged within the vessel, and causing considerable damage as a result, as well as the potential for weakening the structural integrity of the vessel walls to the point of rupture has limited the applicability of this technique. In the final analysis, stents have a tainted usefulness insofar as they may alleviate the stenosed condition for a short period, but may preordain and require a full bypass procedure if the vessel begins to re-stenose (which occurs in a vast number of such cases).
It is also a failure of the present instrumentation that as with many such devices of the prior art, all of these devices are considered fully disposable, and are, in fact, thrown away after a single use. They are complicated devices, having multiple moving parts, requiring substantial structural integrity and, therefore, expense in manufacturing. The fact that they are used only once, and no part can be used again render the use of such devices expensive and wasteful of resources.
In addition to this failure, as can be readily observed from the preceding descriptions, the prior art devices suffer from numerous other limitations, which would be desirable to overcome. These includes the requirement that the surgeon manually actuate all of the feature
Kenyon & Kenyon
Power Medical Interventions, Inc.
Truong Kevin T.
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