Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1996-08-16
2001-02-27
Nguyen, Anhtuan T. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S538000, C604S103040
Reexamination Certificate
active
06193706
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to the field of guidewires. Guidewires are used to position catheters in exploratory procedures, diagnosis, and treatment of various medical conditions. More particularly, this invention relates to a guidewire extension system for connecting or coupling a guidewire, primary or initial wire to an extension or secondary wire during a medical procedure.
BACKGROUND OF THE INVENTION
Guidewires are used in various medical procedures to position medical devices at desired locations within a patient's vascular system. Guidewires, which are steerable, are inserted and maneuvered through the patient's vasculature to a previously chosen location. Once in place, the guidewire provides the means to place a non-steerable device, such as an over-the-wire catheter, at the chosen vascular site. For example, a catheter is slid over the guidewire until the catheter, or some working portion thereof, is positioned within the vasculature at the desired location. Generally speaking, guidewires of a standard length are longer than the non-steerable devices with which they are used to permit independent movement of the device and the wire.
Angioplasty is one interventional procedure where a guidewire is often used. In angioplasty a dilatation catheter having an inflatable balloon structure is used to compress occlusive or blockage material against the sides of a vessel, thereby permitting (ideally) circulation to be reestablished. In preparatory procedures, the site of a vascular restriction, occlusion or stenosis is identified. In the usual procedure, the guidewire is inserted into the patient's femoral artery and maneuvered or steered to the location of the restriction. Maneuvering of the guidewire is facilitated by a video X-ray device which allows the physician to observe the movement of the guidewire's distal tip. The guidewire distal tip generally comprises a radiopaque metal to enhance X-ray viewing. A dilatation catheter then is inserted over the guidewire so that its working segment is located adjacent the restriction. Generally this means that the catheter balloon is positioned adjacent the vascular restriction or blockage.
During a simple angioplasty procedure, the dilatation catheter balloon is inflated to open the restriction, and then is removed along with the guidewire. However, complications sometimes arise which prevent the physician from completing this simple procedure. Occasionally the balloon catheter malfunctions. Sometimes a larger (or smaller) balloon is required further to dilate the vascular restriction, or another device or other type of catheter is needed to remove vascular material. For whatever the reason, the guidewire extension system of this invention is used when the catheter, or other such device, has to be removed and replaced with another device or catheter.
In the usual procedure to exchange catheters, the guidewire is removed from the patient, leaving the catheter in the vascular system. An exchange wire is inserted through the catheter and the catheter removed, leaving the exchange wire in place. The new catheter is inserted over the exchange wire and the exchange wire removed and replaced with the guidewire.
It is desirable to keep the guidewire in the patient's vasculature for various reasons. One reason is that the initial placement of the guidewire requires extensive, time consuming, manipulation. Removal and repositioning of the guidewire would be equally time consuming, possibly requiring a patient to be exposed to additional drugs, radiation, and, in general, additional trauma. It is also of importance that once the guidewire has been steered to a position across a lesion, that the crossed lesion position not be lost by removal of the guidewire. Guidewires removed from a crossed lesion may induce spontaneous vascular restriction or closure making repositioning of the guidewire difficult if not precluded.
In those cases where catheter exchange is desired, the physician would simply prefer to remove the catheter over the guidewire, leaving the guidewire positioned in the patient. However, to permit catheter exchange, a guidewire over which a catheter is to be exchanged must be sufficiently long to allow the physician to grip a portion of the wire as the catheter is being withdrawn over the guidewire. This requires the guidewire to be long enough to provide an external portion longer than the catheter in addition to the guidewire portion remaining in the patient.
Unfortunately, a guidewire of sufficient length to provide suitably long external and internal portions has inferior handling characteristics, thereby making more difficult the steering and maneuvering manipulations needed for guidewire placement. The added length also imposes itself on the usually cramped vascular suite thereby causing distractions from other support activities. It is for these reasons that guidewires are usually only slightly longer than balloon catheters, e.g., 20-50 centimeters longer, and that a much longer exchange wire is used only with exchange procedures.
Illustrating the above, a dilatation catheter has a shaft length in the range of about 120 cm to about 150 cm, a suitable guidewire for such a catheter would have a length in the range of about 150 cm to about 180 cm and an exchange wire would have a length in the range of about 260 cm to about 300 cm. As can be imagined from the above, utilization of an exchange wire in an exchange wire procedure is complicated and time consuming. This invention simplifies catheter exchange and eliminates the need to use an exchange wire.
A recent development involves coupling or connecting a second length of wire, sometimes called an extension wire or secondary wire, to the exposed, proximal end of a positioned guidewire. The secondary wire length should be sufficient to allow the catheter to be withdrawn while leaving the primary or lesion-crossing guidewire positioned within the patient's coronary or peripheral vasculature. Various approaches have been suggested for effecting the attachment of an extension wire to a guidewire.
In one approach, such as that described in U.S. Pat. No. 4,922,923 to Gambale et al., a guide wire and an extension are joined together by crimping. A special crimping tool is disclosed in the Gambale et al., '923 patent. A drawback of this approach is that once the wires have been crimped, the connection therebetween is substantially permanent, and the extension wire cannot be detached from the guidewire except by severing it, e.g., by cutting.
Instead of crimping the guidewire to the extension wire, attempts have been made to engage the extension wire to the guidewire frictionally. Such attempts are described, for example, in U.S. Pat No. 5,113,872 to Jahrmarkt et al., and related U.S. Pat No. 5,117,838 to Palmer et al. These two patents disclose a guidewire extension system in which the distal end of the extension wire comprises a small diameter tube in which there is disposed a small diameter, open pitch, flat wire coiled spring. The proximal end of the guidewire has a reduced diameter portion which is inserted into the tube assembly to complete the connection. The reduced diameter proximal end of the guidewire is slightly larger than the internal diameter of the coiled spring of the extension wire, thereby creating a frictional engagement when one is inserted into the other. Palmer et al. disclose the utilization of a swivel joint for minimizing twisting of the extension guidewire when connecting or disconnecting it from the extension wire. A device as described in these two patents would be very difficult to manufacture reliably and apparently requires an alignment tool to ease insertion.
U.S. Pat No. 4,875,489 to Messner et al., discloses an extendable guidewire in which concentric tubular segments are secured to one or the other of the sections to be connected. The inner tubular segment has a longitudinal slot therein which permits it to expand when a cooperating male portion is inserted therein. The outer
Assell Robert L.
Blackledge Victor R.
Thorud Michael S.
Frenchick Grady J.
Lake Region Manufacturing Co., Inc.
Michael & Best & Friedrich LLP
Nguyen Anhtuan T.
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