Abstract:
The disclosed subject matter describes systems and methods of delivering a therapeutic agent, such as a sclerosing agent, to the walls of a blood vessel to perform sclerotherapy. In an exemplary embodiment a catheter includes a guidewire catheter having at least one guidewire lumen extending therethrough and a slidable concentric tube disposed over the guidewire catheter. At least one bellow is coupled to the concentric tube and configured for conversion between an unexpanded and expanded configuration wherein movement of the concentric tube in a first direction causes the at least one bellow to expand and movement of the concentric tube in a second direction causes the at least one bellow to contract. Additionally, the concentric tube contains at least one port for delivery of a therapeutic agent, e.g. a sclerosing agent. The at least one bellow expands and contracts via mechanical forces.

Description:
FIELD OF THE DISCLOSED SUBJECT MATTER 
       [0001]    The disclosed subject matter relates to treating blood vessels using a therapeutic agent. More particularly, the disclosed subject matter relates to a medical device configured to deliver an agent at select locations within a patient&#39;s blood vessel. An exemplary embodiment of such a device includes a catheter having a slidable concentric tube disposed thereon with a plurality of bellows coupled thereto for expansion/contraction to occlude a vessel for delivery of a therapeutic agent, such as a sclerosing agent, to the walls of a blood vessel to perform sclerotherapy. 
       BACKGROUND OF THE DISCLOSED SUBJECT MATTER 
       [0002]    Varicose veins are blood vessels that have become enlarged and tortuous over a period of time. Most commonly, varicose veins occur in veins on the leg, although they can occur elsewhere. Varicose veins are caused when the leaflets of the valves in the blood vessel no longer close properly, thereby allowing for retrograde flow and pooling of blood. 
         [0003]    Varicose veins are most common in the superficial veins of the legs. They are often painful and can produce ankle swelling, skin discoloration, dermatitis or venous eczema, cramps, and skin tightness around the affected region. In severe cases of varicose veins, complications may occur. For example, the varicose veins may become very painful and hinder a person&#39;s ability to work or perform routine motions and exercises. Skin conditions including itching and flaking associated with varicose veins may also predispose a person to skin loss. Development of serious conditions like blood clots, carcinoma, or sarcoma, may also occur. 
         [0004]    As a result, many non-surgical and surgical treatments of varicose veins have been developed. Non-surgical treatments include sclerotherapy, elastic stockings, elevating the legs, and exercise. The traditional surgical treatment has been vein stripping to remove the affected veins. Newer surgical treatments include ultrasound-guided foam sclerotherapy, radiofrequency ablation and endovenous laser treatment. 
         [0005]    Sclerotherapy is a commonly performed non-surgical treatment for treating varicose veins in which a sclerosing agent is injected into the veins to make them shrink. Complications of sclerotherapy are rare but can include blood clots and ulceration. Furthermore, conventional sclerotherapy techniques often result in incomplete and/or uneven treatment along the length of the patient&#39;s blood vessel. 
         [0006]    In order for sclerotherapy to be effective, it is necessary to evenly dispense the sclerosing agent throughout the wall of the vein without using toxic levels of the sclerosing agent. This is not particularly difficult for the smaller veins. However, it is quite difficult or nearly impossible in larger veins. When a larger vein is injected with a sclerosing agent, the sclerosing agent is quickly diluted by the large volume of blood in the vein. As a result, the vein is sclerosed only in the region of the injection. If the procedure is continued, and the injections are far apart, the vein can become disfigured. The problem cannot be cured by injecting a more potent solution of sclerosing agent, because the sclerosing agent may become toxic at such a concentration. Therefore, a need exists for a system that is capable of delivering a sclerosing agent to the varicose vein walls that prevents the dilution of the sclerosing agent into the blood. 
       SUMMARY OF DISCLOSED SUBJECT MATTER 
       [0007]    The purpose and advantages of the disclosed subject matter will be set forth in and apparent from the description that follows, as well as will be learned by practice of the disclosed subject matter. Additional advantages of the disclosed subject matter will be realized and attained by the methods and systems particularly pointed out in the written description and claims hereof, as well as from the appended drawings. 
         [0008]    To achieve these and other advantages and in accordance with the purpose of the disclosed subject matter, as embodied and broadly described, the disclosed subject matter includes a medical device configured for localized delivery a therapeutic agent via a catheter for occluding a blood vessel comprising a slidable concentric tube disposed over the guidewire catheter. At least one bellow is coupled to the concentric tube and configured for conversion between an unexpanded and expanded configuration, wherein movement of the concentric tube in a first, e.g. distal, direction causes the at least one bellow to expand and movement of the concentric tube in a second, e.g. proximal, direction causes the at least one bellow to contract. Preferably, the catheter includes first and second bellows. In some embodiments, the first and second bellows can be components of a plurality of bellows, e.g., three or more. In some embodiments, the catheter comprises a guidewire lumen extending through the length of the catheter. While a guide wire may be preferred by some physicians, it is not required, and the catheter can be made more cost efficiently without a guidewire lumen. The invention contemplates both a catheter with and without a guidewire lumen. 
         [0009]    In an exemplary embodiment, bellows are coupled to the concentric tube. In one embodiment the bellows are first and second bellows. The bellows (regardless of how many) can be configured to have independent operating tubes. Thus with first and second bellows, for example, each of the first and second bellows can be operated by its own tube. Thus, the inflation and/or contraction of one bellow can be independent from the inflation and/or contraction of another bellow. Alternatively, the bellows can be configured to work dependently or in unison, if desired. Each of the bellows can be associated with the concentric tube. 
         [0010]    Additionally, the concentric tube contains at least one port for delivery of a therapeutic agent, such as a sclerosing agent including ethanol. The therapeutic agent is dispensed in the lumen defined in a space between the concentric tube and the guidewire catheter. Further, the at least one port is disposed between a first and second bellow. Preferably, the at least one bellow expands and contracts solely via mechanical forces. 
         [0011]    In accordance with another aspect of the disclosed subject matter, a method of performing sclerotherapy on a blood vessel, e.g. a varicose vein or hemorrhoid, is disclosed which includes advancing a guidewire catheter into the blood vessel to be occluded, wherein a portion of the guidewire catheter is surrounded by a slidable concentric tube disposed thereupon. The slidable concentric tube is coupled to at least two occlusion elements configured for conversion between an unexpanded and expanded position. The slidable concentric tube also contains at least one port disposed between the at least two occlusion elements. In operation, sliding the concentric tube in a first, e.g. distal, direction to cause the at least two occlusion elements to expand and occlude a portion of the blood vessel. Thereafter, a sclerosing agent is dispensed through a space between the guidewire catheter and the concentric tube, such that the portion of the blood vessel proximal of the first occlusion element is exposed to the sclerosing agent. 
         [0012]    Additionally, the method of sclerotherapy disclosed can include reaspirating the sclerosing agent from the occluded vessel, and sliding the concentric tube in a second, e.g. proximal, direction to cause the at least two occlusion elements to collapse and removing the guidewire catheter from the blood vessel. Optionally, the blood vessels can also be compressed with bandages to expedite the procedure. In some embodiments the occlusion elements expand and contract solely via mechanical forces. 
         [0013]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the disclosed subject matter. 
         [0014]    The accompanying drawings, which are incorporated in and constitute part of this specification, are included to illustrate and provide a further understanding of the method and system of the disclosed subject matter. Together with the description, the drawings serve to explain the principles of the disclosed subject matter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    A detailed description of various aspects, features, and embodiments of the subject matter described herein is provided with reference to the accompanying drawings, which are briefly described below. The drawings are illustrative and are not necessarily drawn to scale, with some components and features being exaggerated for clarity. The drawings illustrate various aspects and features of the present subject matter and may illustrate one or more embodiment(s) or example(s) of the present subject matter in whole or in part. 
           [0016]      FIG. 1  is a schematic view of a catheter embodying two inflatable balloons; 
           [0017]      FIG. 2  is a cross-sectional views of the catheter of  FIG. 1 , taken along line A-A; 
           [0018]      FIG. 3  illustrates a schematic view of the occluding apparatus depicting first and second expandable members in an expanded configuration; 
           [0019]      FIG. 4  illustrates a schematic view of the occluding apparatus depicting first and second expandable members in an collapsed configuration; 
           [0020]      FIG. 5  illustrates a flow chart of the various steps of the system disclosed herein. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0021]    It is understood that the subject matter described herein is not limited to particular embodiments described, and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present subject matter is limited only by the appended claims. 
         [0022]      FIG. 1  depicts a conventional dual balloon catheter having two spaced-apart balloons, e.g., the occlusion balloon  40  and dilatation/occlusion balloon  50 , as disclosed in U.S. Pat. No. 7,060,051, the entirety of which is hereby incorporated by reference. The outer catheter  10  is configured with two lumina (not shown). The catheter can include a distal orifice  90 , a metal marker  120  to enable x-ray identification of the location of the dilatation/occlusion balloon, and a catheter segment  20  that connects the two balloons. Extending through the orifice  90 , a guidewire  34  has a stop plug  170  which can be used to cap the orifice  90 . A plurality of ports or holes  70  extend through the wall of the catheter segment  20  which permits a biologically active agent to pass from an inner lumen in the catheter segment  20  to the exterior of the catheter segment  20  and thereby target treatment to the section of the body lumen between the two balloons or the occluded portion of the body lumen. The inflatable balloons of such conventional designs require a pressure source to deliver inflation medium, e.g. fluid, at elevated pressures to pneumatically or hydraulically expand the balloons. Accordingly, and as shown in  FIG. 1  a plurality of Y connectors,  140  and  160  with side ports  130  and  150  are required with connections  100  and  110  for supplying the pressurizing medium. 
         [0023]      FIG. 2  shows an exemplary embodiment of a cross-sectional view of the catheter of  FIG. 1  at section A-A. The outer catheter is shown with two lumens  35  and  33 . An inner catheter stem  31  is shown inserted into lumen  33  and this stem  31  has two lumens  30  and  32 . This view shows that four different lumens are required to provide independent pressure control to occlusion balloon  40  and balloon  50 , to deliver a biologically active agent through the holes  70 , and to receive the guidewire  34 . The outer catheter  10  is configured with two lumina. The lumen  35  serves to supply the pressurizing medium to the occlusion balloon  40  while the lumen  33  permits a biologically active agent to be delivered to a targeted vessel portion. The lumen  30  serves to supply the pressurizing medium to dilatation/occlusion balloon  50  while lumen  32  can be used to receive guidewire  34 . Consequently, such conventional dual balloon catheter designs require a complex catheter construction including at least three separate channels within the catheter to service the two balloons and to deliver the therapeutic agents through the catheter holes  70 . Such conventional devices can present numerous manufacturing challenges. 
         [0024]    The device and methods of the presently disclosed subject matter do not require the complexities of the conventional dual balloon embodiment, and thus alleviate the burdens of such intricate catheter designs with distinct lumens and connections to external pressurized fluid sources. Examples of such conventional dual balloon occlusion catheters are described in U.S. Pat. Nos. 7,077,836; 6,997,898 and 5,665,063, each of which is hereby incorporated by reference in their entirety. 
         [0025]    Instead, and in accordance with an aspect of the presently disclosed subject matter, a sleeve or sheath  200  which is configured as a concentric tube is coupled to the catheter  10  in slideable fashion such that the sleeve  200  can move proximally and distally along a length of the catheter  10 . The concentric tube  200  includes a plurality of bellows  220 ,  240  coupled thereto which can convert between expanded (as shown in  FIG. 3 ) and unexpanded or collapsed configurations (as shown in  FIG. 4 ). The concentric tube  200  includes a mechanism (not shown) which extends to the proximal end of the catheter to allow for a physician to slide the concentric tube  200  proximally and distally to thereby contract and expand the bellows  220 ,  240 . Preferably, the catheter  10  is advanced in the body lumen with the expandable members, i.e. bellows  220 ,  240  in the collapsed or unexpanded configuration. This is advantageous in that the reduced profile of the collapsed bellows  220 ,  240  eliminate or reduce the occurrence of friction or tearing along the inner wall of the blood vessel. 
         [0026]    Once the catheter reaches the desired location, the concentric tube  200  can be displaced in the proximal and distal directions with respect to the catheter. The concentric tube  200  is connected via a mechanical linkage to the bellows  220 ,  240 . Accordingly, as the concentric tube  200  is advanced in a distal direction the bellows  220 ,  240  expand to occlude the blood vessel. 
         [0027]    The direct mechanical linkage between the concentric tube  200  and bellows  220 ,  240  provides the physician with controlled expansion/contraction based on gradual sliding of tube  200 . For example, ratio of movement between the tube  200  and bellows  220 ,  240  can be 1:1 such that one unit, e.g. cm, of displacement results in one unit of expansion/contraction of the bellows, though alternative ratios are contemplated to be within the scope of the present disclosure. Additionally, the physician can choose a slow constant expansion/contraction rate or abruptly expand/contract the bellows by sliding the tube  200  accordingly. Furthermore, in some embodiments each bellow  220  and  240  can expand at the same rate and to the same degree via solely mechanical forces (i.e. no hydraulic or pneumatic pressure is required). Additionally, or alternatively, the bellows  220 ,  240  can be configured to expand at different rates and/or to different degrees. 
         [0028]    Additionally, the expandable bellows  220 ,  240  can be designed to expand to any diameter as so desired, thereby accommodating a wide range of vessel sizes in a single design. The relative positioning, i.e. distance between bellows  220 ,  240  can also be selected as so desired to occlude any predetermined length of a blood vessel. 
         [0029]    The concentric tube  200  is disposed on the catheter in such a manner that an annular space or lumen is defined between the outer surface of the catheter  10  and the inner surface of the concentric tube  200 . During the medical treatment a therapeutic agent is delivered through this lumen and dispenses into the vessel via ports  230  disposed between the bellows  220 ,  240 . 
         [0030]    These ports  230  can be arranged in a uniform pattern along the length of the concentric tube  200 , or alternatively, be configured in a predetermined varied density pattern such that the tube  200  exhibits a varied dispensing/concentration. For example, the tube  200  can be configured with a greater number of ports  230  at one end to provide for a higher concentration of agent delivered to localized areas of the vessel wall. Accordingly, it will be obvious to one of ordinary skill that the number and location of the ports  230  can be varied to distribute the therapeutic agent within the occluded vessel section in any manner as so desired. 
         [0031]    Upon dispensing, the therapeutic agent interacts with the inner walls of the occluded portion of the blood vessel to provide the desired medical treatment, such as sclerotherapy. Additionally, after the desired amount of therapeutic agent is dispensed into the vessel and the inner walls of the blood vessel have been exposed to the agent for a predetermined time to achieve the desired efficacy, the therapeutic agent can be re-aspirated out of the occluded section of the vessel. This is achieved by withdrawing the therapeutic agent from vessel through ports  230 . 
         [0032]    Upon completion of the sclerotherapy treatment, the concentric tube  200  is displaced in a proximal direction. This proximal displacement of tube  200  engages the mechanical linkage coupled to the bellows to cause contraction or collapse of the bellows  220 ,  240 . As described above with respect to expansion, in some embodiments each bellow  220  and  240  can contract at the same rate and to the same degree via solely mechanical forces (i.e. no hydraulic or pneumatic pressure is required). This is advantageous in that it ensures proper and complete collapse of the bellows, thereby minimizing risk of damage to the inner wall of the blood vessel. Additionally, or alternatively, the bellows  220 ,  240  can be configured to collapse at different rates and/or to different degrees. While the direction of tube displacement described above indicates that distal movement of the tube causes expansion and proximal displacement of the tube causes contraction, it is to be understood that this orientation can be reversed if so desired. 
         [0033]    For purpose of illustration and not limitation, Sclerosing agents compatible with the present invention include, but are not limited to, alcohols such as ethanol or polidocanol (POL), as well as sodium tetradecyl sulphate (STS), Sclerodex, hypertonic saline, glycerin and chromated glycerin, or combinations thereof. These sclerosing agents have been found to effect the cellular responses to growth stimulation and cause the vessel walls to immediately shrink upon exposure to the agents. While specific examples of sclerosing agents are described herein, it is to be understood that alternative therapeutic agents can be administered to the vessel wall utilizing the device and methods disclosed herein. Accordingly, as used herein, a “therapeutic agent” includes any agent that promotes health, recovery or diagnosis. For example, the therapeutic agent may be a drug, protein, or contrast agent. 
         [0034]    A method of performing sclerotherapy in accordance with the presently described subject matter is also included herein. Now, with reference to  FIG. 5 , a flowchart is provided illustrating steps for performing sclerotherapy using the different embodiments of the device described herein. First, the catheter is inserted into the blood vessel to deliver the concentric tube to the desired location at  502 . Next, the concentric tube is advanced in a distal direction to expand the bellows at  504 . The space between the occlusion elements, i.e. bellows, in the blood vessel defines the region for performing sclerotherapy. The sclerosing agent is then delivered through the ports of the concentric tube at  506 . After the sclerosing agent has been imparted to the walls of the blood vessel, the sclerosing agent is removed or re-aspirated from the blood vessel at  508 . The concentric tube is then retraced in a proximal direction to collapse the bellows at  510 . Thereafter, the occlusion elements (i.e. concentric tube and bellows) and catheter are withdrawn from the vessel. Additionally, in some sclerotherapy treatments, the patient&#39;s blood vessels can be compressed via external bandages to facilitate the efficacy of the treatment and expedite the procedure. 
         [0035]    While the disclosed subject matter is described herein in terms of certain preferred embodiments, those skilled in the art will recognize that various modifications and improvements may be made to the disclosed subject matter without departing from the scope thereof. Moreover, although individual features of one embodiment of the disclosed subject matter may be discussed herein or shown in the drawings of the one embodiment and not in other embodiments, it should be apparent that individual features of one embodiment may be combined with one or more features of another embodiment or features from a plurality of embodiments. 
         [0036]    In addition to the specific embodiments claimed below, the disclosed subject matter is also directed to other embodiments having any other possible combination of the dependent features claimed below and those disclosed above. As such, the particular features presented in the dependent claims and disclosed above can be combined with each other in other manners within the scope of the disclosed subject matter such that the disclosed subject matter should be recognized as also specifically directed to other embodiments having any other possible combinations. Thus, the foregoing description of specific embodiments of the disclosed subject matter has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosed subject matter to those embodiments disclosed. 
         [0037]    It will be apparent to those skilled in the art that various modifications and variations can be made in the method and system of the disclosed subject matter without departing from the spirit or scope of the disclosed subject matter. Thus, it is intended that the disclosed subject matter include modifications and variations that are within the scope of the appended claims and their equivalents.