Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-09-30
2001-08-28
Kennedy, Sharon (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S107000
Reexamination Certificate
active
06280414
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a device and method for delivering a therapeutic substance to a treatment site within a patient. More particularly, the device and method are useful for delivering therapeutic drugs to the site of a vessel which has undergone an angioplasty procedure.
BACKGROUND OF THE INVENTION
In treatment of specific areas or organs of the human body with drugs or other therapeutic substances, it is preferable to provide the therapeutic substance only to the area that needs treatment, rather than delivering the substance generally through the blood stream. Localized delivery of a therapeutic substance avoids any undesirable effects that the substance may have on other areas of the body that do not need treatment. Furthermore, localized delivery provide the intended treatment site with a more concentrated dose of the therapeutic substance because it has not been diluted during its travel through the blood stream. Thus, the treatment can be more effective. An additional benefit of localized delivery is that a reduced quantity of the substance can be used to treat the intended location than would otherwise be required to supply a patient's entire blood stream with a quantity sufficient to create a beneficial concentration of the substance for the intended treatment site. The reduction in required quantity results in substantial savings in cost associated with the treatment, especially where the therapeutic substance is an expensive pharmaceutical.
In treatment of vessels for coronary artery disease, stenosed regions are frequently treated by direct delivery of a therapeutic substance. Commonly, the stenosed area of the vessel is first dilated with an angioplasty balloon catheter prior to or during the delivery of the therapeutic substance. The objective of localized drug treatment of the vessel after angioplasty is to reduce the rate of restenosis, or reclosure of the vessel. Vessels which have undergone angioplasty frequently suffer from restenosis, an abrupt closure of the vessel which quickly blocks the flow of blood and can be fatal. Therefore, drugs such as anti-coagulants are applied to an area of the vessel which has recently undergone angioplasty, usually immediately following the procedure.
A common mechanism for delivering a therapeutic substance to an internal location such as a vessel that has recently undergone angioplasty has been delivery through a porous balloon catheter. Generally, such catheters are configured similar to conventional dilatation balloon catheters with the modification of small holes formed into the balloon through which may flow a therapeutic substance under pressure. The substance is also used as the inflation medium for the balloon. Although the inflated balloon places the perfusion outlets in close proximity to the vessel wall to be treated, expulsion of the therapeutic substance necessarily requires inflation of the balloon, which temporarily blocks the blood vessel being treated. Interruption of blood flow through the vessel is undesirable because it can cause pain and discomfort to the patient. Also, delivery through a porous balloon limits the choice of agents that may be delivered as it is undesirable to mix multiple therapeutic agents within the single inflation lumen and balloon of the delivery catheter.
Variations of the porous balloon concept have been provided in an attempt to address the shortcomings of the porous balloon. Balloons have been disclosed that have multiple lumens extending through or on the balloon wall which contain and perfuse therapeutic substances independent of the inflation medium used to expand the body of the balloon. Some of these devices provides means for delivering more than one substance simultaneously. U.S. Pat. No. 5,713,860 (Kaplan et al.) discloses an infusion catheter having an inflatable member over which may be applied several lumens containing one or more therapeutic substances. Because it is important to present the source of therapeutic substance as close as possible to the intended treatment site, the conduits disclosed in the Kaplan patent are expanded by an inflatable member to be in close proximity to the vessel wall. The inflatable member is provided with slits which form into passageways to permit some blood flow through the area when the member is expanded during drug delivery. However, the inflatable member occupies a sizable cross-sectional area of the vessel when expanded, which may serve to interrupt blood flow during drug delivery.
It would be desirable to provide a device for localized delivery of a therapeutic substance, particularly for use in a vessel, which is configured to permit expansion of delivery conduits into close proximity of or in contact with the treatment site without inflation of a balloon which may serve to restrict blood flow through the treatment area. It is an objective of the present invention to provide such a device.
SUMMARY OF THE INVENTION
The present invention provides a therapeutic substance delivery device and method which provides for the positioning of at least one delivery conduit in close proximity with the intended treatment site independent of the expansion of an inflatable member such as a balloon. The embodiments of the present invention utilize at least one flexible conduit which can be buckled to form a bowed configuration to place its perfusion ports in close proximity to tissue such as a vessel to be treated. The delivery device may be used with or without a balloon angioplasty catheter to provide immediate delivery of a therapeutic substance after an angioplasty procedure. It is noted that throughout the discussion of the present invention that proximal refers to the direction along the delivery path of the device leading to the exterior of the patient and distal refers to the path along the delivery device leading to the interior of the patient.
In one embodiment of the present invention, one or more flexible tubes or conduits are arranged to extend parallel with a shaft such as a wire or flexible hypotube. The distal ends of the conduits are joined to the distal end of the shaft in an end cap while the more proximal regions of the shaft and conduits are held in parallel relationship to one another within a multi-lumen outer catheter, each of the conduits and shaft slidably contained within a separate lumen of the catheter. The proximal ends of the conduits may be joined to one or more sources of therapeutic substances which are intended to be delivered to the treatment site. Distal portions of the conduits not contained in the outer catheter have perfusion ports along their length and can bow radially outward under longitudinally compressive loading applied by moving the shaft relative to the conduits.
The assembly may be navigated through the vessels to the treatment site much as would be a conventional catheter. During delivery, the conduits may be held in tension to extend substantially parallel to the longitudinal axis of the shaft along their entire length. However, the distal portions of the conduits are expandable to be in close proximity to the treatment site by sliding the shaft and conduits relative to each other. Specifically, relative movement of the shaft in a proximal direction relative to the conduits, or movement of the conduits in a distal direction relative to the shaft, causes the shaft to be placed in tension while the conduits are placed in compression. Thus, the flexible conduits buckle in a region where they are not supported by the outer catheter. By placing the distal end of the outer catheter proximal to the distal end of the shaft and conduits, an expandable array of distal portions of the conduits is created. Perfusion ports formed along the distal portion of the conduits along their radially outward facing side permits the ejection of a therapeutic substance into or in close proximity to the wall. Delivery of the substance close to the wall of the vessel prevents the substance from being washed away with the flow of blood because the velocity profile of blood flowing thro
Forcucci Stephen J.
Gambale Richard A.
Shah Chirag B.
Kennedy Sharon
Medtronic Ave Inc.
Sterne Kessler Goldstein & Fox P.L.L.C.
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