Patent Application
20060224175
The invention pertains to methods and apparatuses that permit a medical practitioner such as a doctor to add functionality such as distal protection to medical devices such as guidewires.
Guidewires are one of the most common devices used in intravascular procedures. They are designed to be easy to navigate to the treatment site and they permit other therapeutic devices to be advanced easily to the treatment. Guidewires with a distal protection element such as a filter or balloon are becoming more common. A distal protection element provides one common means of controlling any emboli that may be created by a procedure. Guidewires may be highly specialized to provide quicker or easier access to particular intravascular sites and it may be difficult or expensive for a hospital or clinic to keep in stock all the guidewires a practitioner may desire to use. This problem (i.e. keeping a wide stock of guidewires on hand) is compounded with the introduction of new features such as distal protection to guidewires.
One embodiment of the invention pertains to a method of converting a non-distal protection guidewire into a distal protection guidewire. A desired guidewire is selected by the medical practitioner. A stopper is affixed to the guidewire at a desired location and a desired distal protection device is loaded onto the guidewire to create a distal protection guidewire. The stopper may be distal to the distal protection device or may be proximal. In one embodiment, the distal protection device is trapped between a distal stopper and a proximal stopper. In another embodiment, the stopper is integral with the distal protection device.
Another embodiment of the invention pertains to a stopper for the conversion of a guidewire. The stopper has a first state where it has a larger lumen enabling it to be slid to a desired location on a guidewire and a second state where it has a smaller lumen and may be affixed to the guidewire. The stopper may be affixed by crimping or by adhesive. Another embodiment is a stopper made from a shape memory material that is affixed to a guidewire when it approaches body temperature. Another embodiment is made from a spring material that is biased to be in the second state.
The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings in which:
Reference is now made to the figures, in which like element numbers refer to like elements throughout.
This combination can be made by a medical practitioner at a hospital or clinic shortly prior to the therapeutic procedure in which the distal protection guidewire is used. Thus a distal protection guidewire can be customized by selecting a preferred guidewire, a preferred distal protection device and a preferred arrangement of the components (i.e. where the distal protection device is placed on the guidewire). Selective use of one or more stoppers 8 is used to make the conversion.
A stopper 8 has a longitudinal lumen 10 as can be seen in
In one embodiment, the stopper is made from a plastically deformable material such as gold, silver, tin, or alloys thereof. Other such materials may be suitable. The term “plastically deformable” herein means that the stopper is made of such a material that, in moving from the first state to the second state, it will undergo plastic deformation. Such a stopper may be affixed to a guidewire by crimping. A crimping tool such as a pliers may be provided. The crimping tool may have jaws to receive the stopper and the jaws may have a pair of surfaces that have profiles that are inverse of the profile of the stopper. For example, if the stopper has a spherical profile, the jaws may include a pair of spherical indents sized and shaped to receive the stopper. The crimping tool may also include a stop to prevent over-crimping of the stopper. This stop may be a pair of opposing surfaces on the jaws or handles or may be any suitable stop. In some embodiments, a stopper may be packaged preloaded in the jaws of a suitable crimping tool.
In another embodiment, the stopper is a made from a shape memory material such as a nickel-titanium alloy. Other shape memory materials may also be suitable. The stopper moves to the first state when brought to body temperature. Body temperature herein means the normal range of temperatures found in the human body. The stopper moves to the second state when heated up from body temperature. In an alternative embodiment, the stopper may move to the second state when cooled down from body temperature. In some embodiments, the temperature at which the stopper moves to the second state is higher than body temperature, 150 degrees Fahrenheit for example, but not so hot as to melt the polymers typically used in many guidewires. In one example installation, this stopper is heated to an installation temperature where it is in the first state and slid onto a guidewire, where it is allowed to cool down to the second state. The cooling may be hastened if desired by immersing the stopper in a sterile fluid or pouring a sterile fluid over the stopper.
In another example embodiment, the stopper is made from a spring material such as a spring steel that is biased towards the second state. The stopper is expanded to the first state, slid to a desired location on a selected guidewire and released to snap back to the second state. In one embodiment, the stopper is packaged in the second state, with a spacer holding slit 12 open. The spacer may have a handle thereon with which the stopper/spacer combination may be easily manipulated and with which the spacer can be easily removed from the stopper.
In one example use, a guidewire is modified by a medical practitioner as described above and as shown in one of
In another example use, a stopper 8 is affixed to a guidewire. The guidewire is then introduced percutaneously. A distal protection device is then introduced over the guidewire. The stopper 8 ensures the distal protection device won't slide off the distal end of the guidewire.
In another example use, a stopper 8 is affixed to a guidewire. An implantable filter such as a vena cava filter is loaded distal the stopper and is confined in a compact position by a catheter. The filter is introduced to a desired location and the guidewire may be used to push the filter distally from the end of the catheter or may be used to keep the filter from moving proximally as the catheter is withdrawn from over the filter. The catheter and guidewire are then withdrawn, leaving the filter installed.
To provide a medical practitioner with flexibility, stoppers 8 may be offered in various sizes to fit on guidewires of various outer diameters. Each stopper may be packaged in a separate sterile package. Installation tools may be manufactured inexpensively from a small number of parts such as molded plastic parts and each stopper may be packaged preloaded in an appropriate installation tool in a sterile package. The stoppers may also be packaged as a set with one or two stoppers packaged with an appropriate distal protection device. The packaging may include a spacer passing through the lumen of the stopper, which may provide easier handling of the stopper and may keep the stopper in the first state. The stopper may be easily slid off the spacer
Numerous advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood, however, that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of parts without exceeding the scope of the invention. None of the description in the present application should be read as implying that any particular element, step, or function is an essential element which must be included in the claim scope. Moreover, none of these claims are intended to invoke 35 U.S.C. § 112, ¶ 6 unless the exact words “means for” are followed by a participle. The invention's scope is, of course, defined in the language in which the appended claims are expressed.
