Abstract:
An apparatus, a kit and a method for rapidly restoring blood flow through, and removing a clot from, a blood vessel by chemical dissolution. The essential components include an instrument for preventing the flow of debris downstream of the clot, a coronary catheter constructed to be introduced into the blood vessel and a double balloon catheter that has a tapered tip and that can form an enclosed space containing the clot and via which dissolution fluid can be brought into contact with the clot.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to the treatment of arterial obstructions, and particularly blood clots in a blood vessel, such as a coronary artery. 
         [0002]    It is known that most heart attacks are caused by the formation of a blood clot in a coronary artery and that the damage caused by a heart attack can be minimized by prompt medical intervention. In the case of a massive heart attack, 50% or more of the volume of the blockage consists of clot. Conventionally, this intervention primarily consists of a technique and apparatus that provides restoration of blood flow, with or without clot removal. 
         [0003]    However, the appliances currently available for performing such an intervention are relatively costly, their utilization requires highly specialized training, and only a limited number of facilities are equipped to provide the necessary treatment. These facilities require a formal interventional cardiac catheterization laboratory. 
         [0004]    Moreover, many heart attack victims, estimated at 50%, are too remote from a hospital equipped to carry out such a treatment to be able to receive the necessary treatment sufficiently quickly to minimize damage to heart muscle (minutes mean muscle death), and to prevent death. 
       SUMMARY OF THE INVENTION 
       [0005]    With these difficulties in mind, the present invention provides a novel combination of devices, or instruments, that can be made more widely available and a method for their use that can be practiced with less specialized training. 
         [0006]    More specifically, the invention provides a method and apparatus for rapidly reestablishing blood flow, in a blood vessel through which blood normally flows in a given direction and in which an obstructing clot has formed and then substantially eliminating the clot. 
         [0007]    The apparatus includes: 
         [0008]    a standard guide wire that may have any diameter suitable for insertion into the blood vessels that will be encountered in a treatment and which may, for example, have a diameter of 0.014″ or 0.035″, and may be hollow for use as part of a pressure sensor; 
         [0009]    a first catheter, such as a coronary catheter, dimensioned to be inserted into the blood vessels and having an internal lumen dimensioned to allow passage of a first blocking device; and 
         [0010]    a second catheter dimensioned to be inserted into the blood vessel in the direction of blood flow, the second catheter having:
       a longitudinal axis, a tapered distal end, a proximal end, and an outer lateral surface;   a longitudinal lumen extending along the longitudinal axis from the proximal end and opening at the distal end;   blood inlet openings extending from the lateral surface and communicating with the longitudinal lumen;   blood outlet openings extending from the lateral surface at a location adjacent, but proximal to, the tapered distal end and communicating with said longitudinal lumen;   a balloon inflation lumen extending from the proximal end and having two openings at the lateral surface at first and second locations spaced apart along the longitudinal axis and located between the blood inlet opening and the distal end, the balloon inflation lumen being isolated from the longitudinal lumen;   a fluid delivery lumen extending from the proximal end to the lateral surface at a third location between the first and second location, and isolated from the longitudinal lumen and the balloon inflation lumen; and   first and second balloons attached to the outer surface of the second catheter and each having an internal volume communicating with a respective one of the openings of the balloon inflation lumen at a respective one of the first and second locations.       
 
         [0018]    According to an optional second embodiment of the invention, the apparatus further includes a blocking device comprising a tube and an expandable component for blocking a flow of debris from the clot at a location downstream of the clot with respect to the direction of blood flow. 
         [0019]    The present invention also contemplates a kit composed of the components described above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIGS. 1 and 2  are elevational views of two devices, or instruments, employed in the practice of the present invention. 
           [0021]      FIG. 3  is a cross-sectional view of a further instrument employed in the practice of the present invention. 
           [0022]      FIGS. 4 and 5  are elevational views of further instruments employed in the practice of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]      FIG. 1  shows a conventional guide wire  12  having, as is typical of guide wires, a diameter of the order of 0.014″ or 0.035″, and which may be hollow for use as part of a pressure sensor. 
         [0024]      FIG. 2  shows two exemplary components of apparatus according to the present invention. The first component is an essentially straight, large diameter, guide catheter, or sheath,  22  having a diameter of the order of 8-10 Fr (Fr=French; 3 Fr=1 mm). The second component is a coronary catheter  24  having a pre-shaped distal end  25 . Coronary catheter  24  may have an outer diameter of between 5 and 6 Fr and an inside of diameter between 1.2 and 1.8 mm, preferable, 1.4 or 1.6 mm, sufficient to allow passage of any of guide wire  12  or a sheath of sufficiently small diameter. Catheter  24  may, only by way of example, be a type of superselective coronary catheter. Both catheters  22  and  24  are resiliently flexible to the extent that they can be straightened out by guide wire  12 , or a sheath, extending through them. 
         [0025]    An example of catheter  22  is described in U.S. Pat. No. 4,581,017, which is incorporated herein by reference, and which discloses in detail the manner in which such a catheter is controlled to enter a coronary artery. 
         [0026]    Other known types of coronary catheters can be employed in the practice of the present invention. 
         [0027]      FIG. 3  illustrates a double balloon catheter  30  having a treatment fluid/suction lumen  32 , a longitudinal lumen  33 , and a balloon inflation lumen  34 , lumens  32  and  34  being formed in the catheter wall. Attached to the outer wall of catheter  30  are low pressure, high compliance blocking balloons  35  and  36 , each having an internal volume communicating with outlet orifices of lumen  34 , which extend to the outer wall of catheter  30 . Balloons  35  and  36  thus differ in compliance, and thus the required expansion pressure, from the low compliance balloons employed to expand a stent after an angioplasty procedure, which employ catheters having an outer diameter of 4 Fr to 6 Fr. 
         [0028]    Catheter  30  has, at its distal, or forward, end, a relatively long, progressively tapered tip  38  that may be fabricated in a manner to be more rigid than the body of the catheter in order to facilitate passage of the catheter through a clot. 
         [0029]    Catheter  30  has a diameter of at least 4 Fr, and preferably 6 Fr, and tip  38  may have an axial length of 1 to 4 cm, the length presently preferred being 3 cm, although catheters having larger diameters and longer tips may be useful in certain situations and for certain patients. The free end of tip  38  may have an outer diameter of 0.018″ and an inner diameter of 0.016″ to accommodate a 0.014″ guide wire. These dimensions may be increased if a larger diameter guide wire is to be used. However, in all cases, the inner diameter of the free end of tip  38  should be only slightly larger than the diameter of the guide wire. Tip  38  can be made of Teflon-nylon material. 
         [0030]    Catheter  30  is also provided with blood bypass inlet openings  37  and blood bypass outlet openings  39  that communicate with longitudinal lumen  33  to form, with lumen  33 , a blood bypass path intended to quickly establish blood flow around a clot when catheter  30  has been introduced into the blood vessel to extend across the clot, as will be described below. The open distal end of catheter  30 , i.e., the tip, provides an additional blood bypass flow outlet opening. Bypass outlet openings  39  are preferably located in the wall of catheter  30  just ahead of tip  38 , as shown. 
         [0031]    Lumen  33  will have a diameter that is approximately 70-75% of the outer diameter of catheter  30 . Preferably, the cross-sectional area of the blood bypass path, including the total area of openings  37  and the total area of openings  39 , as well as lumen  33 , will be 0.036″. The wall thickness of catheter  30  may be of the order of 0.3 mm. 
         [0032]    Equipment necessary for supplying treatment fluid and/or applying suction to lumen  32  is connected to the proximal end of catheter  30  outside of the patient&#39;s body. 
         [0033]    Catheter  30  has a form similar to those disclosed in my U.S. Pats. Nos. 5,380,284 and 7,169,171, but differs essentially in that catheter  30  has a combination of two blocking balloons and a specially configured tip. 
         [0034]      FIGS. 4 and 5  shows components of one example of the blocking device referred to earlier herein. The component shown in  FIG. 4  is composed of a second guide wire  42  that carries, at its distal end, a collapsible, self expanding filter  44  constituted by a filter membrane  46  supported by a frame (not shown) and a plurality of struts  48  connecting membrane  46  to guide wire  42 . Membrane  46  is fabricated to have a porosity sufficient to allow passage of blood components while retaining debris resulting from the dissolution or disintegration of a blood clot. 
         [0035]    Filter  44  may be constructed as disclosed in issued U.S. Pat. No. 6,485,502, which issued on Nov. 26, 2002, the disclosure of which is incorporated herein by reference. Struts  48  and the frame supporting membrane  46  are made of resiliently deformable material that assures that the filter will expand when not confined and can be made of a material that is expandable and contractible 
         [0036]    However, filter  44  can be fabricated in any other suitable way that is known in the art. 
         [0037]      FIG. 5  illustrates a sheath  52  having an internal diameter sufficient to allow passage of guide wire  42  and filter  44  in its collapsed state. By way of example, sheath  52  may have an outer diameter of 1.1 mm and an internal diameter, defining a lumen, of the order of 1 mm or less. 
       Basic Treatment Procedure 
       [0038]    Phase 1: According to the basic procedure, after the affected artery has been identified, an incision is made in the groin, arm, or wrist, after which guide wire  12  is inserted through a needle into the artery exposed by the incision, through the artery exposed by the incision, and through the aorta, to a location close to, or in, the coronary artery containing the blockage to be removed. 
         [0039]    Optionally, a conventional procedure is performed in which large diameter guide catheter, or sheath,  22  is first introduced through the artery exposed by the incision and into, and possibly through, the aorta in order to facilitate subsequent introduction of guide wire  12 . Guide catheter or sheath  22  is used to guide the introduction of all catheters and filter used for this procedure, and for a modified procedure to be described below, and may be withdrawn at any time after guide wire  12  has been thus positioned. 
         [0040]    Phase 2: Then, a second catheter, which may be any known type suitable for the purpose, such as coronary catheter  20 , is introduced over guide wire  12  to the entrance to the affected coronary artery, and possibly into that artery. 
         [0041]    Phase 3: Thereafter, the guide wire is withdrawn. 
         [0042]    Phase 4: Then the exact location of the clot is determined, for example fluoroscopically and with the introduction of contrast fluid, through the second catheter. 
         [0043]    Phase 5: After the clot has been thus located, the second catheter may be advanced to a point close to the clot. 
         [0044]    Phase 6: Then, guide wire  12  is reintroduced, or another, steerable, guide wire is introduced, through and past the second catheter and through the clot. 
         [0045]    Phase 7: The second catheter is then withdrawn and double balloon catheter  30  is introduced over the guide wire and advanced along the guide wire and then through and beyond the clot until the clot is straddled by the balloons. Tapered tip  38  of double balloon catheter  30  facilitates penetration of the catheter through the clot. 
         [0046]    Phase 8: The guide wire is then withdrawn to open the blood bypass passage  37 ,  33 ,  39  in double balloon catheter  30  and thus immediately establish blood flow across the clot. Balloons  35  and  36  are then inflated to create an isolated region surrounding the clot. Then, a dissolution agent, or infusate, is introduced through lumen  32  to the region surrounding the outer surface of double balloon  30  catheter and enclosed by balloons  35  and  36  in order to dissolve the clot. 
         [0047]    Phase 9: The dissolved clot material, debris and infusate are suctioned from the area being treated through lumen  32  and, after it has been determined that the clot has been at least substantially dissolved, a clot inhibiting substance, such as heparin or bivalarudin, is introduced into the treatment region. After an appropriate time has passed, the clot inhibiting substance will be withdrawn. 
         [0048]    On rare occasions, parts of the clot may escape the confines of the balloons on the double balloon catheter. If this should occur, however, such parts will remain relatively close to the treatment region because the blood flow rate downstream of double balloon catheter  30  will be low as long as the balloons remain inflated. To determine whether a piece of clot has escaped, the region downstream of the double balloon catheter may be observed fluoroscopically with the aid of contrast fluid introduced through central lumen  33  of double balloon catheter  30 . If a piece of clot is observed, further dissolution agent may be introduced via central lumen  33  and further fluoroscopic observations may then be undertaken until complete dissolution is confirmed. 
         [0049]    Phase 10: Then, balloons  35  and  36  are deflated and double balloon catheter  30  is withdrawn from the patient. Thereafter, in accordance with standard procedure, the clot inhibiting substance can continue to be administered. 
         [0050]    From time to time during the procedure, fluid with dissolved clot material can withdrawn via lumen  32 , and a sample of the fluid withdrawn via lumen  32  may be analyzed in order to measure the concentration of dissolution fluid in the enclosed region. Contrast fluid may also be periodically introduced to monitor the progress of the dissolution treatment. 
         [0051]    The various instruments employed in the procedure would be introduced through a manifold located outside of the patient&#39;s body. Such manifolds, and procedures for their use, are already well known in the art. For example, suitable manifolds for this purpose are marketed by the company Navilyst Medical, Inc. of Marlborough, Mass. One suitable manifold is marketed under the product name 3 port manifold. 
       Modified Procedure 
       [0052]    A second clot removal treatment procedure according to the present invention would be performed in special situations, such as when a vein graft has been closed by a clot mass, or the clot mass is extensive and elongated, and the treatment can be performed in a suitable equipped facility such as a cath lab. 
         [0053]    The modified procedure corresponds to the basic procedure, with the modifications to be described below. 
         [0054]    Phases 1-5 are performed as described above. 
         [0055]    Phase 6 is replaced by the following procedure. If necessary, catheter  24  may be withdrawn and sheath  52  is introduced through outer guide catheter  22 . Filter  44  carried by guide wire  42  is initially stored in collapsed form within the longitudinal lumen of sheath  52 . Sheath  52  with filter  44  retained therein, is advanced through, and to a point past, or downstream of, the clot. Then, sheath  52  is withdrawn from the patient&#39;s body to enable filter  44  to open automatically to block flow of debris in the artery at the location downstream of the clot. 
         [0056]    Phase 7 is modified only in that only outer guide catheter  22  is withdrawn, catheter  24  having been withdrawn in the preceding phase. 
         [0057]    Phase 8 is modified only to the extent that guide wire  42  is not withdrawn. Blood can continue to flow past the clot through inlet openings  37 , lumen  33 , outlet openings  39  and filter  44 . Some blood can flow out of catheter  30  around guide wire  42  and through to central opening at the end of catheter  30 . 
         [0058]    Phase 10 is modified only to the extent that after catheter  30  is withdrawn, sheath  52  is reintroduced to capture, i.e collapse filter  44 , which filter may then contain trapped debris, after which sheath  52 , guide wire  42  and filter  44  are withdrawn from the patient. 
         [0059]    It should be noted that one important function performed by the double balloon catheter disclosed herein is to provide blood flow across clot obstructing a blood vessel. This alone will restore the patient&#39;s condition. Thus, the application of the device and its construction recognizes the primary role of a shunt. 
         [0060]    The apparatus and procedure according to the invention can be used to treat clots that occur in other locations, i.e., in other blocked arteries, including peripheral, renal, mesenteric and pulmonary arteries, in the brain, and in blocked veins, including peripheral and renal veins. With respect to arteries, this can include those of the leg, mainly the larger arteries such as the femoral and popliteal, and to arteries that supply the kidneys. Clots occurring in any of the three main arteries supplying the abdomen, would be eminently suitable candidates for this procedure. These arteries are the celiac, superior mesenteric and inferior mesenteric. 
         [0061]    Clot obstructions in arteries may be caused by disease in the arteries but more commonly are due to embolism from the heart. The same considerations apply to the arteries in the arms, these being the subclavian and the brachial arteries. 
         [0062]    With respect to veins, blood clots in veins are extremely common and arise due to abnormalities in clotting seen in cancer, after surgery of the hip, following immobilization, and during airplane flights. These blood clots can migrate into the pulmonary artery and cause death. 
         [0063]    With respect to other vascular structures, patients having kidney dialysis frequently develop clotting in their arteriovenous shunts which are used to insert dialysis devices. This could be another condition treated according to the present invention. 
         [0064]    The double balloon catheter described herein is mainly used when the inside wall of an artery ruptures, leading to a clot and what is described in the medical literature as an “acute coronary syndrome” colloquially referred to as STEMI. STEMI stands for ST change in the electrocardiogram in the situation of a myocardial infarction or a heart attack. Somewhat surprisingly, this is commoner in younger patients than in older populations. The present invention would be of value in treating clots in these young patients. 
         [0065]    Furthermore, if a patient is seen with a stroke after three hours, the standard procedure is to deal with it with local delivery of blood thinners. There is a potential for using the present invention in this situation as well. 
         [0066]    In younger patients, plaque, which constitutes the remainder of the obstruction, normally has an elastic consistency and allows larger catheters to traverse the obstructed area than one would mathematically calculate. In older patients, rupture of the plaque and clot seldom occurs as the plaques are hard, calcified and rigid. Thus, it is possible to use larger catheters in massive heart attacks, which are colloquially referred to as STEMI. Procedures using the apparatus according to the present invention can be employed on patients with STEMI myocardial infarctions in which clot predominates as a causative source of the problem. 
         [0067]    The apparatus according to the invention can also be used, particularly according to the modified procedure described earlier herein, to dissolve a clot that blocks a stent, a frequent occurrence. In this situation it would be necessary to use the double balloon catheter and place it directly within the region enclosed by the stent, or with the balloons straddling the stent, to remove the clot that is contained within the stent. Whether or not a filter needs to be used will depend on the size of the artery in which the stent is implanted and the purpose of the catheter will change to one that primarily is focused on the removal of the clot. Since stents are put into all types of arteries ranging from the carotids and vertebrals to the head, the femorals in the legs, the renals in the kidneys, the mesenterics in the gut, the coronaries in the heart, the size of the arteries will vary from 10 mm to 3 mm. 
         [0068]    The apparatus according to the invention can also be used to deliver materials mixed in with the blood, such as anticancer drugs or other agents such as stem cells and genes. 
         [0069]    In certain situations, passage of the double balloon catheter in a vein may cause pieces to break off from the clot and flow downstream. If such a situation appears to be possible, the procedure employing the apparatus according to the invention for removing a clot from a vein may be carried out in the following alternative manner: 
         [0070]    After the clot has been located, and possibly guide catheter  22  has been advanced to a point close to the clot, sheath  52  with filter  44  retracted therein is advanced through the clot and when the distal end of the sheath reaches an appropriate point beyond the clot, sheath  52  is withdrawn while guide wire  42  is held in place so that filter  44  is deployed to extend across the vein at a location downstream of the clot. Then, sheath  52  is completely removed and catheter  30  is advanced over guide wire  42  to a point at which balloons  35  and  36  straddle the clot. Then, the balloons are inflated, dissolution fluid is introduced to dissolve the clot, further treatments can be performed, and the apparatus removed, all as described earlier herein. 
         [0071]    The following Table lists many of the uses of the apparatus according to the invention. The column labeled “THROUGH FLOW” identifies the importance of maintaining a bypass flow during treatment. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 THROUGH 
                 CLOT 
                   
               
               
                   
                 ORGAN 
                 FLOW 
                 DISSOLUTION 
                 COMMENTS 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 ARTERY 
                   
                   
                   
                   
               
               
                 Coronary 
                 Heart 
                 Very important 
                 Less important 
                 Appropriate catheter selected 
               
               
                   
                   
                   
                   
                 depending on obstruction 
               
               
                 Bypass Vein 
                 Heart 
                 Very Important 
                 Very important 
                 1 or more clots may be present 
               
               
                 graft 
               
               
                 Coronary 
                 Heart 
                 Not important 
                 Very important 
                 Entry through coronary sinus 
               
               
                 veins 
               
               
                 Pulmonary 
                 Lung 
                 Not important 
                 Very important 
                 May be done medically or surgically 
               
               
                 veins 
               
               
                 Carotid 
                 Neck or 
                 Very important 
                 Important 
                 Can be done in the neck or head 
               
               
                 artery 
                 brain 
               
               
                 Renal 
                 Kidney 
                 Important 
                 Very important 
                 The clots may arise from the heart 
               
               
                 Artery 
               
               
                 Femoral 
                 Legs 
                 Less important 
                 Very important 
                 Includes the illiac, popliteal and 
               
               
                 Artery 
                   
                   
                   
                 superficial femoral 
               
               
                 Mesenteric 
                 Gastro- 
                 Less important 
                 Very important 
                 There are 3 separate blood vessels 
               
               
                   
                 intestinal 
                   
                   
                 supplying the Gastrointestinal tract 
               
               
                   
                 &amp; Liver 
               
               
                 VEINS 
               
               
                 Jugular 
                 Brain 
                 Not important 
                 Very Important 
                 This group applied to veins in the 
               
               
                 veins 
                 (Cerebrum) 
                   
                   
                 head supplying the brain 
               
               
                 Deep veins 
                 Calf 
                 Unimportant 
                 Very important 
                 A major health problem which is 
               
               
                 of the calf 
                   
                   
                   
                 unresolved 
               
               
                 Large veins 
                 Body 
                 Not important 
                 Very important 
                 Local delivery-important 
               
               
                 PROSTHETIC 
                 Heart 
                 Very important 
                 Very important 
                 Balloons sit astride the valve 
               
               
                 VALVES 
               
               
                 STENTS 
                 Heart 
                 Important 
                 Very Important 
                 This is a significant problem with 
               
               
                   
                 Kidney 
                   
                   
                 out a proper solution 
               
               
                   
                 Carotid 
               
               
                   
                 Mesenteric 
               
               
                   
                 Femoral 
               
               
                   
               
             
          
         
       
     
         [0072]    While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention. 
         [0073]    The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.