Abstract:
A hand held motor powered device for percutaneous thrombolysis and evacuation of a clot from a clotted arterio-venous fistula is disclosed. The percutaneous thrombectomy device is provided with a plurality of nested coaxial lubricious catheters. The multi-functional thrombectomy device can simultaneously and sequentially degrade and evacuate a blood clot from a blood vessel by multiple modalities that combines to degrade the clot by mechanical agitation, fragmentation and disruption, by peri-thrombus delivery of enzymatic fluids, by irrigation with biocompatible fluids, and by balloon displacement. The thrombectomy device further provides for balloon containment and isolation of clot debris from the general circulation, thereby minimizing the risks to a patient of embolic sequelae. There is also provided an optional steering mechanism for controlled deflection of the working end of the device.

Description:
FIELD OF THE INVENTION 
     The subject invention relates to a medical device for lysis and evacuation of a clot within a blood vessel. In particular, the present invention is directed to a device for percutaneous thrombectomy, i.e. the thrombolysis and evacuation of an intravascular thrombus in a living mammal. Even more particularly, the present invention directs itself to a medical device for percutaneous thrombolysis and evacuation of clot from a clotted arterio-venous fistula. 
     Furthermore, the subject invention is directed to a percutaneous device for clot thrombectomy by a number of simultaneous and sequential modalities, comprising a plurality of displaceable and coaxial catheter members for mechanical agitation, fragmentation and disruption of a thrombus; for peri-thrombus infusion of and irrigation with biocompatible fluids; for peri-thrombus delivery of pharmacologic agents; and for displacement and evacuation of an intravascular clot with at least one reversibly inflatable balloon-like member important for the containment of clot fragments and debris and their subsequent controlled removal from the vascular system. 
     Additionally, the present invention relates to a hand-held medical thrombectomy device for percutaneous placement of a catheter assembly comprising at least one balloon catheter member; a guidewire; an optionally steerable tined catheter having a plurality of radially displaceable and rotatable resilient tines coupled to an electrically or hydraulically powered motor unit  200  housed within the handle and activated with an actuating mechanism; and further provided with at least a pair of irrigation catheters, assembled for the mechanical and/or enzymatic lysis of a clot within a blood vessel and/or arterio-venous (“AV”) fistula and/or vascular graft, containment of clot debris by the inflated balloon(s), and subsequent irrigation and removal of macroscopic and microscopic clot debris from the vascular compartment. 
     With further particularity, the subject invention directs itself to a hand-held percutaneous thrombectomy device having a plurality of respectively displaceable coaxial catheter members, and further provided with an actuating handle unit allowing the simultaneous and/or sequential activation of the subject invention&#39;s available thrombolytic modalities, including but not limited to clot disruption by mechanical shearing and maceration; mechanical fluid agitation from expansible rotatory actions of expandable and resilient distal catheter tines; peri-thrombus delivery of thrombolytic pharmacologic agents; and clot capture and controlled displacement using at least one slidably displaceable inflatable catheter member. 
     BACKGROUND OF THE INVENTION 
     Patients with end-stage renal disease, regardless of etiology, require hemodialysis several times a week as an absolute medical necessity. Furthermore, such dialysis-dependent patients have chronic pulmonary compromise due to ventilation perfusion mismatching. Consequently, end stage renal patients have an increased susceptibility to further pulmonary insults, which may include the accumulated micro-thrombi that can shower the pulmonary microvasculature as micro-emboli during relatively uncontrolled thrombolytic and thrombectomy interventions. 
     Hemodialysis necessarily, inherently requires a reliable vascular access supplied with a robust blood flow that can support the associated large fluid and blood volume shifts. In order to provide adequate vascular access, an AV fistula is surgically created by anastamosing a peripheral artery and vein, typically in an arm or leg. The turbulent blood flow within an AV fistula creates areas of relative blood stasis which thereby predispose to thrombus formation and clot growth that often further leads to occlusion of the vascular lumen. Clotted AV fistulae are relatively common, and necessitate surgical clot removal, or synonymously, thrombectomy to salvage the AV fistula vascular access; if the clot is too extensive, it becomes necessary to tie off, which is to say, ligate, the clotted AV fistula and create a new one at another anatomic site. 
     Furthermore, AV fistula thrombectomies are done in an Operating Room since currently available techniques involve either open dissection with arteriotomy access to the clot, or closed techniques with the associated increased risks of uncontrolled hemorrhage, both situations requiring the concentrated resources available in an operating room. 
     It is a goal of the present invention to provide a medical thrombectomy device that can safely be used outside the operating room, whether in a facility x-ray suite or dialysis unit, in a procedure room or bedside. 
     It is also a goal of the subject invention to provide for optimal thrombectomy by the combined effects of mechanical agitation and shearing and balloon displacement with peri-thrombus delivery of pharmacologic agents. 
     It is an important objective of the present invention to minimize the size of the access puncture into the blood vessel in order to insert the thrombectomy devices&#39; nested coaxial catheters. 
     PRIOR ART 
     Thrombectomy devices are well known in the prior art. For example, patent application publication US 2002/0010487 is directed to expansible shearing catheters for thrombus removal, providing for expansible baskets comprised of helically oriented independently flexible struts that function as cooperating radially expansible shearing members. The inner basket may be rotatably driven and may use an axial pump extending proximally from the shearing members. 
     U.S. Pat. No. 5,928,218 teaches a minimally invasive assembly that comprises a tubular member with a large-diameter distal end portion and a smaller diameter proximal portion, a clot-intake port at the distal end and a cutter element that is movably disposed in the distal end of this tubular device for cutting or macerating or severing material that is sucked into the intake port. The device assembly further encompasses a balloon at the distal end of the tubular member that is inflated with irrigation fluid controlled by a valve that operationally responds to the position of the cutter element. 
     U.S. Pat. No. 5,102,415 is directed to an apparatus for removing blood clots from arteries and veins, a triple catheter with an outer catheter that can be inserted into a blood vessel; an inner catheter with an inflated balloon at its distal end. The intermediate catheter is radially expandable at its distal end with a receptacle that is an elastic mesh structure made of spring wires or similar plastic monofilaments. By utilizing a self-expanding basket or end receptacle mounted on the intermediate catheter, the basket is supposed to drag along the walls of the vessel and be able to clear away the thrombus without leaving any clot portions in the blood vessel. 
     U.S. Pat. No. 6,663,613 uses an “agitator” to effect clot dissolution in addition to introducing a thrombolytic agent within the clot. The mechanical agitation itself breaks up the clot to some extent and the addition of a thrombolytic agent aids with the dispersal of that pharmacologic substance and a synergistic effect for clot disruption. The mechanical agitation means on the catheter body may be a radially expansible agitator that is rotatable and/or axially translatable relative to the catheter body. Alternatively, the radially expansible agitator may comprise a resilient element which can be axially shortened so as to assume an enlarged profile and then straightened and so on. By cycling the expansible agitator element through straightening and arching by axial shortening, mechanical energy is translated into breaking up the clot. U.S. Pat. No. 6,652,548 is a similar device of the same inventors, with distal balloon tipped catheter containment of the thrombus as well as proximal balloon catheter containment, coupled with a thrombus removal catheter. 
     U.S. Pat. No. 4,762,130 discloses and claims a thrombectomy catheter with a radially expansible corkscrew-like balloon at the tip of a percutaneously placed catheter. The distal end of the catheter is advanced at least partly through the thrombus with the balloon in a contracted or deflated condition and once in position, the corkscrew-like balloon is inflated, thereby expanding into its helical configuration so as to engage the clot. The helical balloon at the catheter tip has sealing loops permitting the flow of blood within the vessel in order to propel the catheter along inside the vessel. The catheter is further provided with a plurality of lumens that allow injection of diagnostic and thrombolytic agents, etc. The inflation of the radially expansible helical balloon is done with the catheter tip just past the thrombus so that the expanding helix lies within the blood clot; withdrawing the catheter is then akin to withdrawing a cork from a wine bottle. 
     There exists a need for a medical device to accomplish a thrombectomy that is percutaneously placed, encompasses thrombolysis by the concurrent and sequential application of mechanical agitation, shearing, fragmentation, maceration and cutting, pharmacologic degradation of the clot, balloon containment of clot debris, balloon displacement of clot to an evacuation port, irrigation of the area around the clot with saline or other biocompatible fluid, and which further allows substantially one-handed deployment and operation of these thrombectomy modalities. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the percutaneous thrombolysis device in the deployed condition; 
         FIG. 2  is a cross-sectional side view of the undeployed device positioned with a guidewire advanced to the level of a clot in a blood vessel; 
         FIG. 3  is a cross-sectional side view of the device having the tines deployed, the device being positioned with a balloon tipped catheter proximal to a clot in a blood vessel; 
         FIG. 4  is a cross-sectional side view of the device having the deployed tines rotating and further having an inflated balloon member positioned proximal to a clot in a blood vessel; 
         FIG. 5  is a cross-sectional side view of the device in the deployed condition; 
         FIG. 6  is a side-view of the thrombolysis device in the undeployed condition; and, 
         FIG. 7  is a functional cross-sectional side view showing the respective catheter members of the medical percutaneous thrombectomy device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The details of the percutaneous thrombectomy device  100  may be best appreciated with reference to the Figures.  FIG. 1  illustrates the medical thrombectomy device  100  in perspective view, showing the device  100  in a deployed operable condition. At the proximal end, ‘proximal’ being understood to signify the direction toward the handle and the device operator, a handle housing  120  is seen with the telescoping displaceable control housing  140  in a partially retracted position having the tines  185  partially exposed and radially expanded. The irrigation catheters  190 ,  195 , which consist of both an infusion catheter  190  and an evacuation catheter  195 , are fixedly connected or attached to control housing  140  through which they pass. 
     Protruding longitudinally away from the handle housing  120  is a control housing  140 , a hollow semi-rigid displaceable cylindrical extension in which a plurality of catheter members are slideably contained. Catheters  190 ,  195  are fixedly connected to control housing  140  so as to move together as a unit upon longitudinal displacement  200  for the deployment, or un-deployment, of the functional distal end of the device  100 . The irrigation catheters  190 ,  195  fixedly attached to control housing  140 , are slidingly received into a recess  122  formed in the handle housing  120 , the recess having a length substantially equal to distance  135  of catheter- 190 &#39;s longitudinal excursion between operable and protected conditions. 
     The plurality of coaxially positioned catheters comprises an evacuation catheter  195  coaxially positioned around an infusion catheter  190 , with each of the catheters secured to the control housing proximally. The catheters extend through the control housing  140  and terminate proximally with a catheter connector formed at a proximal opening of each catheter  190 .  195 . As illustrated in  FIG. 7 , the proximal ends of the irrigation catheters  190 ,  195  exit from the control housing and are connectable to any standard fluid conduit such as IV tubing, irrigation syringes and so on. The catheters have an opening, also referred to as a fenestration, formed in the outer surfaces of the catheters at a location in line with the through conduit  150 . These fenestrations are hermetically sealed with an elastomeric member having a self-sealing aperture centrally positioned: these are often referred to as diaphragms and they allow a guidewire  160  and a balloon catheter  170  to be passed through the self-sealing central opening in the diaphragm and be advanced into the catheter lumens while maintaining a fluid-tight seal. 
     Activation mechanism  125  is depicted mounted in handle housing  120  and allows an operator to start the thrombectomy device motor  200  housed in the handle  120 , which in turn rotates tines  185  along with catheter  180  from which the tines  185  are formed. The motor  200  is preferably powered by a battery  210  housed within the handle housing  120  but power may alternatively be supplied by an external source including electrical, mechanical and pressurized fluid sources. Further appreciated in  FIG. 1  is the arcuately elongate shaped displacing guard  126  which is pivotally displaceable from a closed position in which it blocks inadvertent activation of activation mechanism  125 , to a more distal forward open position allowing activating access to activation mechanism  125 . Displacing guard  126  is thus pivotally displaceable forward and away from the blocking position to an un-blocking position, as illustrated, that allows access to activation mechanism  125 . The displacing guard is constrained in its pivotal displacement from contacting or activating the activation mechanism  125 . Importantly, the pivotal displacement of the guard  126  simultaneously controls the longitudinal displacement  200  of control housing  140  and catheters  190 ,  195  attached thereto. The functional effect is that displacing guard  126 , which is connected to control housing  140  within housing  120 , longitudinally displaces the telescopically displaceable catheter assembly  140 ,  190 ,  195  from a operable condition to a protected condition and vice versa. 
     The telescoping displacement of the catheters  190 ,  195 —longitudinally  200  in a distal direction to form a sheath to cover tines  185  when in the protected condition, and in a proximal direction to an operable or retracted condition with tines  185  unsheathed—incorporates a locking mechanism. The preferred locking mechanism is illustrated as a detent locking mechanism  141  comprising a plurality of reversibly engaging detent locking members. Other locking member embodiments include—but are not limited to—a sliding bolt action; a latch mechanism; and so on. Such locking members as are functionally equivalent are within the contemplation and scope of the present subject invention. 
     Spring biased detent balls engage respective detent recesses formed in corresponding surfaces of handle housing  120  and control housing  140  respectively. While it is preferred that spring biased detent balls be formed in the handle housing  140  and the respective detent recesses  141  formed in the outer surface of control housing  120 , it is equivalent for the recesses to be formed in the handle housing  120  and the matching detent balls formed in the respective control housing  140 . The recesses are situated to reversibly secure the control housing in the handle housing both in the operable and in the protected conditions. The device reversibly locks the respective position of the control housing  140  and handle housing  120 , with both the protected condition and also the operable or retracted condition effected upon the pivotal displacement of a displacing guard  126  connected to control housing  140 . In the preferred embodiment it is the displacing guard which is used to cause the longitudinal displacement of control housing  140  with respect to handle housing  120 . 
     The device  100  is in an operable condition when control housing  140  is longitudinally displaced proximally to a reversibly complementary juxtaposition with the handle housing  120 , which thereby uncovers tines  185 , allowing the tines  185  to expand radially. 
     Additionally, as seen illustrated in  FIG. 1  there is optionally provided a control wheel  118  that is steerably connected to the fusiform tip  182  of catheter  175  thereby providing controlled displaceability to the working end of the device  100 . 
     Coaxial and interior to the evacuation catheter  195  is an infusion catheter  190 ; coaxial and interior to both the irrigation catheters  190 ,  195  is a tined catheter  180 . Tined catheter  180  has formed at its distal aspect a plurality of resilient radially expandable finger-like tines  185  that are allowed to expand radially upon the proximal longitudinal displacement  200  of control handle  140  together with evacuation catheter  195  and infusion catheter  190 . Tined catheter is not longitudinally displaceable with respect to the handle housing  120  and is secured in the longitudinal axis by its connection with the motor  200  gearing (or similar frictional engagement members) and/or other anchoring means well known to those skilled in the art of medical devices. 
     Also illustrated in  FIG. 1  the balloon tip catheter  170  is positioned interior to and coaxial with the other catheters  180 ,  190 ,  195 , and is formed with a valved reversibly inflatable member at its distal end proximal to the radially expandable tines  185 , a fusiform member  182  of the balloon catheter  170  is formed. Guidewire  160  is advanced along the through conduit  150  positioned longitudinally through the thrombolysis device  100 ; the guidewire  160  occupies a central, axial position relative to the nested coaxial catheters  170 ,  180 ,  190 , and  195 . The distance  135 , from the proximal end of the fusiform member  182  to the distal opening of evacuation catheter  195  is the telescoping distance, the maximal extent of longitudinal displacement for the control handle  140  having the irrigation catheters  190 ,  195  attached. The displacement proximally along direction  200  which is to say the excursion of the fixed irrigation catheters  190 ,  195  into handle recess  122  is substantially the same distance as the telescoping distance  135 . 
     As seen in greater detail in  FIG. 2  and in subsequent  FIGS. 3-5 , the plurality of nested telescoping coaxial catheters, seen here positioned within the lumen of a blood vessel  20  with guidewire  160  advanced to the level of a thrombus or clot  25 . In operation, guidewire  160  is first advanced percutaneously into the blood vessel with a clot; the through conduit  150  of the medical device  100  provides a hollow channel into which to insert an end of guidewire  160 ; the medical device  100  is then passed over the guidewire  160  into position near the clot. 
     In order to facilitate the atraumatic positioning of the nested coaxial catheters, tined catheter  180  is fitted at its distal end with a fusiform or cone-like member  182  that has a maximal outside diameter at its base substantially equal to the outside diameter of the juxtaposing catheter  195 . This smooth profile of the catheter when in the closed conformation serves to minimize the risk of traumatic abrasion or puncture or other damage to the blood vessel and/or surrounding tissues during placement. The device as seen in  FIG. 2  is in the undeployed condition. By this is meant the condition in which the irrigation catheters  190 ,  195  are positioned as far distally as possible so that the distal tip of the evacuation catheter  195  is juxtaposed with the base of the cone-like member  182  forming thereby a relative smooth surface. The expandable tines  185  are reversibly deformed to a collapsed or contracted state, held in that position by the sheath formed by the irrigation catheters  190 ,  195 . 
     All of the catheters  180 ,  190 ,  195  and the guidewire  160  are optionally and preferably provided with a lubricious coating so as to facilitate the working of device  100 . 
     The fusiform catheter tip  182  represents the distal terminal aspect of tined catheter  180 . A steering mechanism optionally attaches to the fusiform catheter tip  182  so as to provide controlled deflectability; the mechanism may be any of the deflecting mechanisms well known to those practiced in the art of medical devices. For example, steering tendons in the form of wires may be used to cause the desired controlled deflection of the functioning end of device  100 . 
     Once the working end of the thrombolysis device  100  is positioned close to the blood clot  25  as seen in  FIG. 3 , the irrigation catheters  190 ,  195  are longitudinally displaced in a proximal direction, thereby disinhibiting the compressed and/or folded expandable tines  185  and allowing them to radially expand. In addition, a balloon-tipped catheter  170  is advanced over the guidewire through the lumen of tined catheter  180  and advanced distally so that the reversibly expandable balloon member  175  comes to rest in a position proximal to the thrombus  25 . The expandable tines  185  displace radially as far as the internal dimensions of the blood vessel  20  permit. Balloon catheter  170  is optionally provided with a second reversibly expandable balloon member located on the opposite side of the tines  185 , for further vascular containment of clot debris  29 . All reversibly expandable balloon members have valves formed proximally in line with the catheter lumens so as to permit controlled inflation and deflation with a fluid under pressure. In the preferred embodiment the preferred fluid is physiologic saline, a 0.9 Normal aqueous solution of sodium chloride. Other biocompatible crystalloids or colloid liquids are likewise preferred. Not shown is the proximal connection of tined catheter  180  to the motor  200 ; rotations of the motor  200  are transferred to the tined catheter causing the tined catheter  180  and the tines  185  formed at its distal aspect to rotate upon activation of the motor  200  by activation, member  125 . The rotational connection is effected preferably by a set of gears or similar engaging members that frictionally transfer the motor&#39;s  200  rotations to the tined catheter  180  causing it to rotate. 
       FIG. 4  shows the next step in the thrombectomy method of the present invention, illustrating the delivery of a biocompatible fluid through infusion catheter  190 . Further illustrated is the radially rotatory displacement of tines  185  in a preferred clockwise movement, allowing tines  185  to degrade the clot  25  by macerating, cutting, shearing and mechanical agitation and displacement. Further seen in  FIG. 4  is balloon  175  in the inflated condition. The inflation of balloon  175  at a position proximal to the clot  25  is important for isolating and containing the clot debris  29  resulting from mechanical disruption, lysis and pharmacologic degradation of the clot  25 . The evacuation of the clot debris  29  and the fluid and blood in which it is carried is seen illustrated in  FIG. 5  as the debris  29  is suctioned into evacuation catheter  195 . 
       FIG. 5  further shows the thrombectomy device  100  having the balloon member  175  inflated with the tines  185  deployed and rotatingly displaced, also positioned with the inflated balloon tipped catheter  170  situated proximal to a clot  25  in a blood vessel  20 , illustrating the evacuation of debris  29 , the direction of rotation of the tines  185 , and the spread of some thrombus material  29  near the containment balloon  175 .  FIG. 5  illustrates how some debris  29  having migrated proximally, which is to say away from the inserted device  100 , may be contained by the inflated balloon  175  to thereby prevent such debris  29  from entering the general circulation with the associated risks of micro emboli and thrombus formations. 
     The functional relationship of the plurality of nested catheters of the thrombectomy device  100  is illustrated in  FIG. 7 . Fluid infusates, with or without pharmacologic agents such as enzymes and other degradative biochemical agents, are introduced through catheter  190 . Catheter  190  has a rigid section  190 A fixedly attached to handle housing  120  and joining flexible sections of catheter  190  both proximally and distally. The connection between the flexible sections of  190  and the rigid section  190 A is accomplished by a hermetic locking mechanism, such as a Luer lock or other similar mechanism. Fluid entering the infusion catheter  190  is directed toward the working end of the device. The infusion catheter is seen to surround the tined catheter  180  which further surrounds balloon tip catheter  170 , still further having guidewire  160  centrally located; the longitudinal sections of all of the catheters are coaxial as schematically illustrated in  FIG. 7 . Fluid is evacuated through catheter  195 , the outermost catheter in the nested catheters of the device  100 , as a result of suction or some other differential pressure creating mechanism. The preferred direction of rotation  230  taken by the tined catheter  180  is indicated; tined catheter  180  has connected at its distal end the plurality of radially expandable tines  185  formed therefrom. 
     Although this invention has been described in connection with specific forms and embodiments thereof, it should be appreciated that various modifications other than those discussed above may be resorted to without departing from the spirit or scope of the invention. For example, equivalent elements may be substituted for those specifically shown and described, certain features may be used independently of other features, and in certain cases, particular locations of elements may be reversed or interposed, all without departing from the spirit or scope of the invention as defined in the appended claims.