Abstract:
The present disclosure relates to intravascular thrombectomy systems and methods for ablating a partial or complete blockage in a blood vessel. The system includes a catheter sleeve defining a lumen extending therethrough; a pair of electrodes disposed at a distal end portion of the catheter sleeve, wherein the pair of electrodes are disposed on opposed sides of the lumen of the catheter sleeve; and a guidewire slidably disposed within the lumen of the catheter sleeve, the guidewire including a capture element supported proximate a distal end thereof, wherein the guidewire is slidable with respect to the catheter sleeve to expose the capture element from the distal end portion of the catheter sleeve; wherein the capture element includes a first condition retracted onto the guidewire and a second condition at least substantially spans the entire lumen of the vessel.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a Continuation Application which claims the benefit of and priority to U.S. application Ser. No. 11/391,620, filed on Mar. 28, 2006, now U.S. Pat. No. 7,749,220, which claims the benefit of and priority to U.S. Provisional Application Ser. No. 60/666,830, filed on Mar. 31, 2005, the entire content of each of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to intravascular thrombectomy systems and methods and, more particularly, to intravascular systems and methods used to ablate a blockage and to prevent the introduction of emboli into the blood stream during and after surgery performed to reduce or ablate the blockage in the blood vessel. 
     2. Background of Related Art 
     As is known in the industry, a thrombosis is the formation or presence of a thrombus or blood clot inside a blood vessel or cavity of the heart. An embolus meanwhile is a thrombus or blood clot that moves through the bloodstream until it lodges in a narrowed vessel and blocks circulation. 
     The narrowing or occluding of blood vessels, such as the walls of an artery, inhibits normal blood flow. Such blockages, whether partial or full, can have serious medical consequences depending upon their location within a patient&#39;s vascular system. For example, the narrowing or blocking of the coronary vessels that supply blood to the heart may cause damage to the heart. 
     Various surgical procedures are currently used to remove or reduce the blockage in the blood vessels. Such procedures include balloon angioplasty, which involves inserting a balloon catheter into the narrowed or occluded area, expanding the balloon in the narrow or occluded area, and if necessary, placing a stent in the now expanded area to keep it open. Another common procedure used is atherectomy where the lesion is cut away and removed from the vessel, or abrasively ground, sending the small particulates downstream. Other endovascular procedures make use of thrombectomy, drug delivery, radiation, stent-grafts, and various diagnostic devices. 
     On occasion, a large thrombus or a platelet-rich thrombus resists pharmacological therapy. In such instances, restoration of adequate antegrade coronary or peripheral flow necessitates application of a device that is capable of removing the thrombus or blockage, as described above. Present mechanical devices for power thrombectomy include ultrasound sonication, rheolytic thrombectomy, laser transluminal extraction catheterization, aspiration catheterization, and balloon angioplasty. 
     Ultimately, the clinical strategy is to use any one or a combination of procedures disclosed above to achieve nearly complete vessel patency, improved antegrade flow, and enhanced preservation of myocardial tissue. 
     However, each of the above described procedures carries with it the risk that some of the treated plaque will be disrupted, resulting in embolic particulates released in the bloodstream. These emboli, if allowed to flow through the vascular system, may cause subsequent infarctions or ischemia in the patient. 
     Systems have been developed to prevent the emboli from being released into the bloodstream during such procedures. For example, in one system, a balloon may be used to completely occlude the artery distal (i.e., downstream) of the area of blockage to be treated. In another system, a filter may be used to prevent emboli from being released into the bloodstream during surgical intervention. 
     SUMMARY 
     The present disclosure relates to intravascular thrombectomy systems and methods. 
     According to an aspect of the present disclosure, a catheter system for ablating a partial or a complete blockage of a corporal vessel is provided. The catheter system includes a catheter sleeve having a distal end portion; a capture element disposed proximate the distal end portion of the catheter sleeve; and at least a pair of axially spaced apart electrodes supported on the catheter sleeve at a location proximal of the capture element. Each electrode is connectable to a source of electrosurgical energy. The capture element has a first condition wherein the capture element is retracted onto the catheter sleeve and a second condition wherein the capture element at least substantially spans the entire lumen of the vessel. The catheter sleeve may be flexible and may enable pushability and trackability. The catheter sleeve may have a gauge of about 0.060 inches. 
     The catheter system may include a source of electrosurgical energy electrically connectable to each electrode. The electrosurgical energy source may deliver an effective amount of energy to the electrodes to ablate the blockage. 
     According to yet another aspect of the present disclosure, a method of ablating a blockage in a corporal vessel is provided. The method includes the steps of providing a catheter system configured and adapted to ablate the blockage. The catheter system includes a catheter sleeve having a distal end portion supporting at least a pair of electrodes thereon, and an electrosurgical energy source connectable to each electrode. 
     The method further includes the steps of introducing the catheter into the corporal vessel, advancing the catheter sleeve through the corporal vessel to the blockage, positioning a capture element downstream of the blockage, and deploying the capture element to at least substantially span the lumen of the corporal vessel. The method further includes the steps of positioning the catheter sleeve within the corporal vessel such that at least one electrode is positioned in close proximity to the blockage, and activating the electrosurgical energy source to energize the electrodes and ablate the blockage. 
     The method may further include the step of delivering an effective amount of energy for an effective amount of time to the blockage. 
     According to one method, the catheter assembly may include a guidewire slidably supported within a lumen of the catheter sleeve. The catheter sleeve may include a pair of electrodes operatively supported at the distal end portion thereof. The guidewire may include a capture element operatively supported on a distal end portion thereof. The capture element may include a first condition wherein the capture element is retracted onto the guidewire and a second condition wherein the capture element at least substantially spans the entire lumen of the vessel. 
     The method may further include the steps of extending the guidewire distally from the catheter sleeve and through the blockage until the capture element is disposed completely beyond the blockage; and advancing the catheter sleeve through the corporal vessel until the distal end portion thereof is in contact with the blockage. 
     According to another method, the catheter sleeve may support a capture element proximate a distal end portion thereof. At least a pair of axially spaced apart electrodes is disposed on the catheter sleeve at a location proximal of the capture element. 
     The method may further include the step of advancing the catheter sleeve through the corporal vessel and through the blockage until the capture element and a distal-most electrode is positioned distal of the blockage. 
     Each electrode of the catheter system may be electrically independent from one another. 
     Additional objects and advantages of the disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
     Both the foregoing general description and the following detailed description are exemplary and exploratory only and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention. In the drawings: 
         FIG. 1  is schematic illustration of a thrombectomy catheter system according to an embodiment of the present disclosure; 
         FIG. 2  is an enlarged view of the indicated area of detail of  FIG. 1 , illustrating the thrombectomy catheter system in a first condition; 
         FIG. 3  is an enlarged view of the indicated area of detail of  FIG. 1 , illustrating the thrombectomy catheter system in a second condition; 
         FIGS. 4A-4D  illustrate a generalized sequence of steps for use of the thrombectomy catheter system of  FIGS. 1-3  for restoration of flow past the occluded site; 
         FIG. 5  is an enlarged schematic illustration of the thrombectomy catheter system of  FIG. 4D , shown in a deployed condition within a blood vessel; and 
         FIG. 6  is an enlarged schematic illustration of a thrombectomy catheter system, in accordance with another embodiment of the present disclosure, shown in a deployed condition within a blood vessel. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Reference will now be made in detail to the present embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, identical or similar reference numerals will be used throughout the drawings to refer to similar or like elements. 
     The present disclosure provides for devices and methods for ablating a blockage and for preventing the introduction of emboli into the blood stream during and after surgery performed to reduce or ablate the blockage in the blood vessel. As used herein, and “occlusion,” “blockage,” or “stenosis” refers to both complete and partial blockages of the vessel. 
     Additionally, as used herein, “proximal” refers to that portion of the device or apparatus located closest to the user, and “distal” refers to that portion of the device or apparatus located furthest from the user. 
     Referring initially to  FIGS. 1-3 , a thrombectomy catheter system, in accordance with an embodiment of the present disclosure, is generally designated  100 . Thrombectomy catheter system  100  includes an elongate catheter sleeve  102  having a substantially tubular configuration. Catheter sleeve  102  defines a lumen  103  (see  FIG. 2 ) extending at least substantially entirely therethrough. Catheter sleeve  102  includes a proximal end portion  106  connected to and/or supporting a handle, hub or manifold  104 , and a distal end portion  108  configured for passage of an elongated shaft  120  therethrough. Catheter sleeve  102  is fabricated utilizing suitable technology to provide catheter sleeve walls having predetermined flexibility characteristics that can allow precise intravascular navigation, pushability and trackability. 
     Thrombectomy catheter system  100  includes at least one electrode  110  disposed at and/or supported at distal end portion  108  of catheter sleeve  102 . Desirably, a pair of electrodes  110   a ,  110   b  is provided at distal end portion  108  of catheter sleeve  102 . Each electrode  110   a ,  110   b  is electrically connectable to a source of electrosurgical energy, such as, for example, an electrosurgical generator “G”, via electrical conduits or wires  112  extending through lumen  103  of catheter sleeve  102  and through hub  104 . Each electrode  110  may be electrically isolated and/or independent from one another. 
     As is described in greater detail below, electrodes  110   a ,  110   b  are preferably used to emulsify emboli or thrombi entrained in fluid flows (i.e., vessels) to prevent clogging of the channel or to ablate the embolus or thrombus to unclog the channel. 
     As seen in  FIGS. 1-3 , thrombectomy catheter system  100  further includes a shaft or guidewire  120  extendable through lumen  103  of catheter sleeve  102 . Guidewire  120  includes a selectively deployable capture element  124  disposed proximate distal end  122  thereof. In one embodiment, capture element  124  is in the form of a filter or cage. Capture element  124  includes a first condition wherein capture element  124  is collapsed or retracted onto guidewire  120 , and at least a second condition wherein capture element  124  is deployed or expanded to preferably span the entire lumen of the vessel or expand into apposition with the targeted vessel. Transformation of capture element  124  may be impelled by external mechanical means, or by self-activating memory material provided within capture element  124 . Such mechanical memory may be imparted to the material of capture element  124  by thermal treatment to achieve a spring temper in stainless steel, for example, or to set a shape memory in a susceptible metal alloy, such as a binary nickel-titanium (nitinol) alloy. Other suitable methods of deploying and retracting capture element  124  will be readily apparent to one having ordinary skill in the art and are incorporated into the present disclosure without departing from the scope and spirit of the present disclosure. 
     In one embodiment, in use, as will be described in greater detail below, guidewire  120  is inserted into the lumen of catheter sleeve  102 , through hub  104 , and slidably advanced therethrough until distal end  122  of guidewire  120  extends out through distal end portion of catheter sleeve  102  and capture element  124  is positioned at or near a desired location within the vessel. 
     In an embodiment, catheter system  100  may also be a fixed-wire system or a rapid exchange system. 
     Turning now to  FIGS. 4A-4D  and  5 , an exemplary method of using thrombectomy catheter system  100  is shown and described.  FIG. 4A  schematically depicts a vessel “V” containing a blockage or clot “B” (e.g., a thrombus, embolus, etc.) completely or substantially restricting blood flow therethrough. As seen in  FIG. 4B , distal end portion  108  of catheter sleeve  102  is introduced into vessel “V” using any suitable technique. 
     A goal of the surgical procedure is to position capture element  124  of guidewire  120  distal of blockage “B”, and to position distal end portion  108 , and more particularly electrodes  110 , against and/or within blockage “B”. Accordingly, as seen in  FIG. 4C , catheter sleeve  102  is advanced through vessel “V” until electrodes  110 , disposed at distal end portion  108 , are in close proximity to, are in contact with, or are positioned within, blockage “B”. With continued reference to  FIG. 4C , distal end  122  of guidewire  120  is advanced through blockage “B” until capture element  124  is disposed distal of blockage “B”. 
     As seen in  FIG. 4D , with capture element  124  of guidewire  120  located distally of blockage “B”, capture element  124  is deployed to span the entire lumen of vessel “V”. Once capture element  124  has been deployed, energy (e.g., thermal, RF, ultrasonic, electrical, plasma, etc.) is delivered to blockage “B” via electrodes  110 . An effective amount of energy is delivered to electrodes  110  for an effective amount of time to ablate blockage “B”. During and following ablation of blockage “B”, any particularized thrombus and/or vapor, resulting from the ablation, is captured in capture element  124  of guidewire  120 . In one embodiment, capture element  124  of guidewire  120  functions to trap and remove particles and/or debris that may flow distally or downstream through vessel “V” during the thrombectomy procedure. 
     As mentioned above, each electrode  110  may be electrically isolated and/or independent from one another. Accordingly, it is envisioned and within the scope of the present disclosure for each electrode  110  to be independently controlled by electrosurgical generator “G”. During the procedure, it may be desirable to limit current flow to and between electrodes  110  when a low impedance path exists between electrodes  110  and a return or common electrode and/or when a high impedance path exists between electrodes  110  and a return or common electrode. Desirably, the energy delivered to electrodes  110  is in the range from about 20 kHz to about 20 MHz, and in the range of from about 5 volts to about 300 volts (RMS). 
     According to one embodiment and method, at least one or each electrode  110  may be configured to deliver plasma or the like. The surrounding blood or other suitable fluid media may be the medium for generating the plasma. 
     In an embodiment, radio-opaque markers (not explicitly shown) may be provided along the length of catheter sleeve  102  and/or guidewire  120 . In this manner, the position and location of the various elements of thrombectomy catheter system  100  (e.g., electrodes  110 , capture element  124 , etc.) may be monitored using conventional monitoring techniques, such as, for example, fluoroscopy and the like. 
     In one embodiment, thrombectomy catheter system  100  has an overall gauge that is less than about 0.060 inches. In this manner, thrombectomy catheter system  100  may enter and pass through present embolic protection devices that may be placed proximally of the blockage “B” during the thrombectomy procedure. 
     Turning now to  FIG. 6 , a thrombectomy catheter system, according to another embodiment of the present disclosure, is generally shown as  200 . Thrombectomy catheter system  200  includes a catheter sleeve or body  202  having a distal end portion  208 . Thrombectomy catheter system  200  further includes at least a pair of electrodes  210   a ,  210   b  disposed or supported thereon. Desirably, electrodes  210   a ,  210   b  are spaced an axial distance from one another and are preferably located proximate distal end portion  208 . While only a pair of electrodes  210   a ,  210   b  are shown and described as being disposed on catheter sleeve  202 , it is within the scope of the present disclosure for any suitable number of electrodes to be disposed along the length of catheter sleeve  202 . 
     If more than a pair of electrodes  210   a ,  210   b  is provided, it may be desirable for the electrodes to be evenly spaced from one another. Additionally, each electrode  210   a  or  210   b  may be electrically isolated from one another. In an embodiment, radio-opaque markers  211  may be provided along the length of catheter sleeve  202 , desirably on either side of each electrode  210   a ,  210   b . Markers  211  provide the user, under fluoroscopic visualization, with the ability to identify when at least a distal-most electrode  210  is located distally of blockage “B”. In one embodiment, each electrode  210   a ,  210   b  may substantially surround catheter sleeve  202 . 
     As seen in  FIG. 6 , thrombectomy catheter system  200  further includes a capture element  224  disposed and/or supported on distal end portion  208  of catheter sleeve  202 . Capture element  224  may be located distally of a distal-most electrode  210   b . Capture element  224  is substantially similar to capture element  124  and will not be discussed in great detail hereinbelow. 
     Capture element  224  is in the form of a filter or cage. Capture element  224  includes a first condition wherein capture element  224  is collapsed or retracted onto catheter sleeve  202 , and at least a second condition wherein capture element  224  is deployed or expanded to preferably span the entire lumen of the vessel or expands into apposition with the targeted vessel. 
     With continued reference to  FIG. 6 , an exemplary method of using thrombectomy catheter system  200 , for performing a thrombectomy procedure, is shown and described. Once again, thrombectomy catheter system  200  is introduced into vessel “V” using any suitable technique. 
     A goal of the surgical procedure of  FIG. 6  is to position capture element  224  through and distal of blockage “B”, and to position catheter sleeve  202  through blockage “B” such that at least one electrode, e.g., distal-most electrode  210   b , is located distal or downstream of blockage “B” and such that at least one electrode, e.g., proximal-most electrode  210   a , is located proximal of or upstream of blockage “B”. Accordingly, in use, catheter sleeve  202  is advanced through vessel “V” and through blockage “B” until distal-most electrode  210   b  is disposed distal of blockage “B” and capture element  224  is disposed distal of blockage “B”. 
     As seen in  FIG. 6 , with capture element  224  of thrombectomy catheter system  200  located distally of blockage “B”, capture element  224  is deployed to span the entire lumen of vessel “V”. Once capture element  224  has been deployed, energy (e.g., thermal, RF, ultrasonic, electrical, etc.) is delivered to blockage “B” via electrodes  210   a ,  210   b . An effective amount of energy is delivered to and between electrodes  210   a ,  210   b , from electrosurgical generator “G”, for an effective amount of time to ablate blockage “B”. During the ablation process, the effective amount of energy is transmitted through blockage “B” between distal-most electrode  210   b  and proximal-most electrode  210   a.    
     During and following ablation of blockage “B”, any particularized thrombus and/or vapor, resulting from the ablation, is captured in capture element  224 . In one embodiment, capture element  224  functions to trap and remove particles and/or debris that may flow distally or downstream through vessel “V” during the thrombectomy procedure. 
     While the devices and methods of the present disclosure have been directed to thrombectomy procedures and the like, it is within the present disclosure for the devices disclosed herein to be used in connection with other procedures equally as well, such as, for example, vascular stenosis, plaque removal, artherectomy and the like. 
     Various modifications may be made to the embodiments of the presently disclosed apparatus, devices and methods. Therefore, the above description should not be construed as limiting, but merely as exemplifications of embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure.