Surgery – Means for introducing or removing material from body for... – With means for cutting – scarifying – or vibrating tissue
Reexamination Certificate
1998-04-30
2001-09-18
Seidel, Richard K. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
With means for cutting, scarifying, or vibrating tissue
C604S510000, C604S523000
Reexamination Certificate
active
06290668
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to light delivery catheters and more particularly to both a light delivery catheter, which may be utilized as a fluid flow catheter, and which permits the rapid exchange of a guidewire and a light guide at the distal end thereof while both components remain in the catheter, and to methods for utilizing such catheter or others for removing a blood clot in a blood vessel, for example, a blood vessel in the brain.
BACKGROUND OF THE INVENTION
Blood clots in cerebral arteries and other vessels of the brain can cause strokes and other neurological problems. It is therefore desirable that these blood clots be broken up and removed. One technique which has been utilized to accomplish this objective in the past is laser ablation. However, because of the tortuous nature of the brain vessels and the vessels leading thereto, moving a catheter into a position to deliver light energy to a clot requires that the catheter, or at least the distal portion thereof, be very flexible, and normally requires that the catheter be advanced over a guidewire to a desired location. However, a light delivery catheter also normally requires a light guide passing through the catheter. But, a catheter having two lumens passing therethrough, one for a guidewire and one for a light guide, would be too stiff, particularly at the distal end thereof, to traverse the tortuous path to the brain; therefore catheters used for ablation of brain clots have heretofore utilized a single lumen, with the guidewire being removed when the catheter is positioned adjacent a clot and a light guide then inserted through the catheter to a position adjacent the clot.
However, in order to avoid damaging parts of the vessel other than the clot, or even puncturing the vessel, relatively low energy is used for such procedures, so that the first delivery of light energy to the clot normally does not result in ablation thereof. In order for the procedure to be most effective, it is desirable that the catheter be repositioned adjacent to the new leading edge of the clot before light energy is again provided. However, it is also preferable that the guidewire be utilized for such repositioning. Therefore, with current equipment, the doctor performing the procedure has had three choices, namely (a) attempt to reposition the catheter without the use of a guidewire; (b) not reposition the catheter and continue ablation from the catheter's original position; or (c) remove the light guide through what may be as much as 150 centimeters (approximately 5 feet) of catheter, reinsert a guidewire to reposition the catheter, and then remove the guidewire and reinsert the light guide. The first procedure is difficult to perform, the second results in reduced energy being transmitted to the clot for subsequent applications of light energy and, because of the tortuous nature of the vessel, may result in light being directed at a portion of the vessel other than the clot, resulting in reduced clot ablation. The third procedure is tedious and time-consuming. Therefore, existing light delivery catheters for laser thrombosis or ablation of blood clots impose limitations on the doctors performing such procedures and result in less than optimum procedures being utilized. The same problems arise where the laser is only used to cavitate the clot and a clot-busting drug such as tPA is used in conjunction with ablation/cavitation to assist in breaking up the clot. This procedure also requires in most instances several iterations of light energy and drug application before the blood clot is fully broken up.
Another potential problem in using a light delivery catheter to remove a blood clot in the brain is that vessel walls in the brain are relatively thin and subject to perforation, particularly by a catheter being pressed there against. This risk is reduced by having a very flexible guidewire being used to lead the catheter through the vessel and by not having an unguided catheter moving forward through the vessel.
Still another potential problem is that, since the blockage at a clot prevents any emboli created during the lysing or ablation process from being washed downstream, such emboli therefore must travel retrograde or upstream to areas of the brain which are unaffected by the clot. These emboli or particles traveling through vessels which may already be narrowed by the presence of the catheter therein can, in a worse case scenario, result in a stoke in such unaffected areas of the brain. It would therefore be preferable if such emboli could be washed or flushed downstream through vessels in area of the brain already affected by the stoke and through vessels not partially blocked by a catheter so as to both reduce the likelihood of a further small stroke and to minimize any new damage caused thereby.
Finally, all of the current procedures for the ablation of blood clots in the brain are relatively time consuming. Since the longer the procedure, the harder it is on both the physician and patient, and the more expensive the procedure becomes, it is desirable that any procedure utilized be as efficient as possible so as to minimize the time required for its performance.
Similar problems may exist when using a light-delivery catheter to remove clots from blood vessels in parts of the body other than the brain. A need therefore exists for an improved light delivery catheter which permits the catheter to be sufficiently flexible, at least in the distal portion thereof, to advance through tortuous brain or other vessels with minimum risk of damage thereto while still permitting rapid exchange between guidewire and light guide so as to facilitate rapid and accurate repositioning of the catheter adjacent the current leading edge of the clot between each delivery of light energy. It is also desirable that the catheter used operate in a fluid flow mode, facilitating the delivery of light energy to the clot and that the procedure used facilitate washing of emboli creating by the ablation process downstream so as to minimize risk of secondary stroke, particularly in unaffected areas of the brain.
SUMMARY OF THE INVENTION
In accordance with the above, this invention provides a light delivery catheter which has a proximal shaft with first and second lumens extending therethrough, a distal shaft having a single lumen extending therethrough and a short tapered section interconnecting the proximal and distal shafts. The first and second lumens are adapted to receive a guidewire and a light guide, respectively, with the single lumen being aligned with the first and second lumens to permit either the guidewire in the first lumen or the light guide in the second lumen to extend into the single lumen in the distal shaft. The distal shaft is flexible and preferably has a distal portion, which may be approximately 1 to 2 centimeters long, which is tapered to enhance flexibility. The entire distal shaft may be approximately 20 to 30 centimeters long. A port may be provided at the proximal end of the proximal shaft through which contrast fluid may be applied to flow through the second lumen and out through the single lumen. The distal shaft is preferably formed of a material having a refractive index which is less than that of such contrast fluid, which material is a floropolymer for preferred embodiments. Both the proximal and distal shaft may be formed of such floropolymer material. Particularly where the catheter is being used with contrast fluid flowing therethrough, the second lumen may be larger than the first lumen. A marker band of a radiopaque material may also be applied at the distal end of the distal shaft.
For preferred embodiments, a light guide is provided in the second lumen and a guidewire in the first lumen of the proximal shaft. A hub is also provided at the proximal end of the proximal shaft, which hub has at least three ports. A first port is connected to the first lumen through which a guidewire may enter the lumen and a second port is connected to the second lumen through which a light guide may enter the seco
Gregory Kenton W.
Porter Christopher H.
Rydell Mark Anders
Ziebol Robert
Hayes Michael J.
Seidel Richard K.
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