Abstract:
A system and associated methods provided for crossing total occlusions in blood vessels. While the system and methods are particularly beneficial for the treatment of coronary artery disease, they are also useful in the treatment of other arteries and veins, such as the treatment of peripheral vascular diseases. The present invention used a system comprised of three unique and specialized components: 1. an anchoring, supporting and centering balloon sheath apparatus; 2. a hydraulic guidewire with removable core; and 3. an exchange sheath.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to medical devices and their associated methods of use. More particularly, the present invention relates to an anchoring, centering, and supporting catheter system and associated procedures for crossing chronic total occlusions in blood vessels using a standard or specialized guidewire.  
         BACKGROUND OF THE INVENTION  
         [0002]    Cardiovascular disease is commonly accepted as being one of the most serious health risks facing our society today. Diseased and obstructed coronary arteries can restrict the flow of blood and cause tissue ischemia and necrosis. After over two decades of investigation, although the exact etiology of sclerotic cardiovascular disease is still in question, the treatment of narrowed coronary arteries is more defined. Surgical construction of coronary artery bypass grafts (CABG) is often the method of choice when there are several diseased segments in one or multiple arteries. Open heart surgery is, of course, very traumatic for patients. In many cases, less traumatic, alternative methods are available for treating cardiovascular disease percutaneously. These alternate treatment methods generally employ various types of percutaneous transluminal angioplasty (PTCA) balloons or excising devices (atherectomy) to remodel or debulk diseased vessel segments. A further alternative treatment method involves percutaneous, intraluminal installation of expandable, tubular stents or prostheses in sclerotic lesions.  
           [0003]    A particularly troublesome form of cardiovascular disease results when a blood vessel becomes totally occluded with atheroma or plaque, referred to as a chronic total occlusion. Until recently, chronic total occlusions have usually been treated by performing a bypass procedure where an autologous or synthetic blood vessel is anastomotically attached to locations on the blood vessel upstream and downstream of the occlusion. While highly effective, such bypass procedures are quite traumatic to the patient.  
           [0004]    Medical catheters such as balloon catheters have been proven efficacious in treating a wide variety of blood vessel disorders. Moreover, these types of catheters have permitted clinicians to treat disorders with minimally invasive procedures that, in the past, would have required complex and perhaps life-threatening surgeries. For example, balloon angioplasty is now a common procedure to alleviate stenotic lesions (i.e., clogged arteries) in blood vessels, thereby reducing the need for heart bypass operations.  
           [0005]    Because medical catheters and guidewires must be passed through a tortuous blood vessel network to reach the intended treatment site, it is desirable that the catheter be fairly flexible, especially at the distal end. However, the distal end must not be so flexible that it tends to bend back upon itself (prolaspe) when the clinician advances the catheters or guidewires distal end through the tortuous vasculature.  
           [0006]    Recently, catheter-based intravascular procedures have been utilized to treat chronic total occlusions with limited success. Catheter-based intravascular procedures include angioplasty, atherectomy, stenting, and the like, and are often preferred over invasive coronary artery bypass graft (CABG) procedures because they are much less traumatic to the patient. In some instances, before an interventional catheter treatment can be performed, it is sometimes necessary to cross a significant occlusion with a guidewire to provide access for the interventional catheter. However, in many cases, the guidewire inadvertently penetrates into the subintimal space between the intimal layer and the adventitial layer of the blood vessel, or worse yet, perforates the arterial wall, as it attempts to cross the occlusion. Once in the subintimal space or perforated, it is very difficult and in many cases impossible to direct the guidewire back into the blood vessel lumen. In such cases, it will usually be impossible to perform the interventional procedure and other, more traumatic, surgical procedures may have to be employed.  
           [0007]    For these reasons, it would be desirable to provide methods and a system that facilitates crossing a chronic total occlusion in a blood vessel. In particular, it would be desirable to provide an anchoring, centering, and supporting catheter system which could be used with a specialized guidewire to direct the guidewire away from the subintimal space and into the occluded blood vessel lumen. Such methods and apparatus should be useful in coronary arteries as well as peripheral and other blood vessels and should be capable of being performed with or without imaging from within or adjacent to the blood vessel.  
         SUMMARY OF THE INVENTION  
         [0008]    According to the present invention, a system and methods are provided for crossing total occlusions in blood vessels. While the system and methods are particularly beneficial for the treatment of coronary artery disease, they are also useful in the treatment of other arteries and veins, such as the treatment of peripheral vascular diseases.  
           [0009]    The present invention uses a system comprised of three unique and specialized components:  
           [0010]    1. An Anchoring, Supporting and Centering Balloon Sheath Apparatus;  
           [0011]    2. A Hydraulic Guidewire with Removable Core; and  
           [0012]    3. An Exchange Sheath.  
           [0013]    The total occlusions are crossed by not forming a track into the subintimal space between the intimal layer and the adventitial layer of a blood vessel, but rather the present invention functions as an anchoring, centering, and supporting catheter system and associated procedures for crossing chronic total occlusions without penetrating the subintimal space. In another embodiment of the present invention, one or more directing wires are provided which present additional control of the general heading or bearing of the guidewire.  
           [0014]    The track of the guidewire is generally directed towards the original luminal space from a location proximal to the total occlusion to a location that is distal to the total occlusion. The Balloon Sheath functions to facilitate the centering of the guidewire into the total occlusion. Hydraulic means is provided which is directed from the tip of the guidewire to provide additional centering through the total occlusion.  
           [0015]    By continuing to advance the wire, it will usually pass substantially through the total occlusion of the original luminal space and can be further advanced to the desired distal location. Now the Exchange Sheath is advanced over the guidewire to further dilate and dotter the channel established by the guidewire. Once the Exchange Sheath is passed through the total occlusion, the hydraulic guidewire or other guidewire can be used to introduce interventional balloons, stents or other devices to achieve a clinically desirable patent vessel lumen.  
           [0016]    In typical methods, the guidewire is directed using an anchoring, centering and supporting balloon catheter. Generally, the balloon catheter is advanced just proximal of the total occlusion with the guidewire advanced to a distal position in the catheter guidewire lumen. A flexible balloon on the distal end of the catheter is inflated to a working pressure whereby the guidewire distal lumen is directed substantially towards the original luminal space. The guidewire and the catheter are then manipulated so that the wire is deflected substantially towards the center of the original lumen. The balloon catheter is also useful in supporting the wire as it is advanced into and/or through the track, i.e. the catheter can enhance the “pushability” of the wire when it is advanced forward through the resisting material. Hydraulic means are provided in the guidewire to perform two functions. Side directed hydraulic means function as thrusters which facilitate the centering of the guidewire through the total occlusion. Forward directed hydraulic means functions to assist pushability of the guidewire through the occlusion.  
           [0017]    It will usually be necessary to determine when the guidewire and/or balloon catheter are positioned distal to the total occlusion so that the wire may be directed towards the center of the blood vessel lumen and beyond said occlusion. Most simply, such position determination can be made by fluoroscopically imaging the blood vessel in a conventional manner. Alternatively or additionally to such fluoroscopic imaging, intravascular imaging, e.g. intravascular ultrasonic imaging (IVUS), and a variety of optical imaging modalities, such as optical coherence tomography (OCT), may be employed.  
           [0018]    After the passage or channel is formed through the occluded blood vessel lumen and the hydraulic wire is in place across the total occlusion, the Exchange Sheath is advanced through the passage or channel to further dilate and dotter the channel. After the Exchange Sheath is advanced through the occlusion, it can be retracted, or the guidewire can be exchanged and then the Exchange Sheath removed. Then either the hydraulic guidewire, a previously placed standard guidewire, or a new guidewire can be available for use in positioning interventional and diagnostic catheters across the total occlusion. Most commonly, interventional catheters will be positioned across the total occlusion for treating the occlusion. Exemplary interventional catheters include angioplasty balloon catheters, rotational atherectomy catheters, directional atherectomy catheters, stent-placement catheters, and the like. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is an illustration of a typical environment that the anchoring, supporting and centering balloon sheath, hydraulic guidewire and sheath apparatus system.  
         [0020]    [0020]FIG. 2 is a cross-sectional illustration of a distal end of the balloon sheath embodiment with the balloon in a deflated configuration.  
         [0021]    [0021]FIG. 3 is a cross sectional illustration of a distal end of the balloon sheath embodiment that employs control wires engaged to the proximal side of the balloon with the balloon in an expanded configuration.  
         [0022]    [0022]FIG. 4 is a cross-sectional illustration of a distal end of the balloon sheath embodiment that employs control wires engaged to the distal side of the balloon with the balloon in an expanded configuration.  
         [0023]    [0023]FIG. 5 is a cross-sectional view taken along the line  5 - 5  of FIG. 2.  
         [0024]    [0024]FIG. 6 is a cross-sectional view taken along the line  6 - 6  of FIG. 2.  
         [0025]    [0025]FIG. 7 is a cross-sectional view taken along the line  7 - 7  of FIG. 3 and line  7 - 7  of FIG. 4.  
         [0026]    [0026]FIG. 8 is a cross-sectional illustration of a hydraulic guidewire with an attached adapter with at least one extension mounted on said proximal end of said guidewire.  
         [0027]    [0027]FIG. 9 is a cross-sectional view taken along the line  9 - 9  of FIG. 8.  
         [0028]    [0028]FIG. 10 is a cross-sectional illustration of an example of the exchange sheath of the present invention system.  
         [0029]    [0029]FIG. 11 is a cross-sectional view taken along the line  11 - 11  of FIG. 10.  
         [0030]    [0030]FIG. 12 is a cross-sectional view of a prior standard guidewire penetrating the vessel wall.  
         [0031]    [0031]FIG. 13 is a cross-sectional view of a prior standard guidewire non-centered into the vessel lumen and entering and advancing into the subintimal space within the medial layer.  
         [0032]    [0032]FIG. 14 is a cross-sectional view of a prior standard guidewire prolapsing within a vessel lumen.  
         [0033]    [0033]FIG. 15 is a cross-sectional view of the present invention hydraulic guidewire in position just proximal of the total occlusion for treatment.  
         [0034]    [0034]FIG. 16 is a cross-sectional view of the present invention balloon sheath in an expanded configuration with the hydraulic guidewire just proximal to the total occlusion.  
         [0035]    [0035]FIG. 17 is a cross-sectional view of the present invention balloon sheath in an expanded configuration with the hydraulic guidewire employing various apertures to further center the guidewire and penetrate the total occlusion. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0036]    With reference now to the exemplary drawings, and particularly to FIGS. 2, 3 and  4  there are shown three cross-sectional illustrations of a distal end of the balloon sheath embodiment with the balloon in a deflated configuration in accordance with the present invention system. FIG. 2 shows a first embodiment  30  of the balloon sheath embodiment with the balloon in a deflated configuration. This FIG. 2 demonstrates that the catheter has a proximal catheter shaft  42  and a distal catheter shaft  32  both of a coaxial design with an inflation lumen  34  and a guidewire lumen  38 . Closer to the distal end the shaft  32  has a slightly reduced diameter with increased flexibly characteristics. The catheter shafts  40  and  32  are typically fabricated from a mixture of low density (LDPE) and high density (HDPE) polyethylenes, or can be manufactured from a variety of thermoplastic polymers know by those skilled in the art in making medical catheters. The distal section of the catheter is fitted with a flexible balloon  36  comprised of a C-flex or latex material that, rather than designed to apply dilatation force to a vessel wall, expands under relatively low working pressures to a substantially spherical balloon configuration. The general characteristic of this catheter assembly is that the flexible (expanded spherical balloon  50 , 56  conforms to the contour of the vessel wall, anchoring the catheter in place. In this position, the balloon  36  now provides support to facilitate centering of an advancing hydraulic guidewire into the lumen of the vessel and through the total occlusion. The present invention system flexible balloon  36  is expanded with relatively low working pressures ranging from 0.5 to 4 atmospheres (atm.), and preferably from 1 to 2 atms. Extending throughout the length of the catheter is a guidewire lumen  38  having dimensional specifications to receive the present invention system hydraulic guidewire. Typically, the guidewire lumen is 0.012″ to 0.020″ in diameter, and preferably 0.014″ to 0.018″. The catheter shaft terminates in a distal opening  39  whereby the hydraulic guidewire protrudes forward from the catheter. Not shown at the proximal end of the catheter is a typical two or three armed adapter which design, materials of construction and means for attaching to the catheter shaft are well know by those skilled in the art.  
         [0037]    [0037]FIG. 3 is a cross sectional illustration of a distal end of the balloon sheath embodiment which employs control wires engaged to the proximal side of the balloon with the balloon in an expanded configuration. Shown on FIG. 3 is a second embodiment  44  of the balloon sheath whereby the catheter/spherical balloon assembly employs a means to attach one or more control wires  52  to the proximal end of the balloon. The proximally attached control wires  52  extend along the length of the catheter and are contained with channels  62  shown in FIG. 7. The channels  62  terminate at the proximal end of the flexible balloon  50 . The proximally attached control wires  52  engage the end of the channel and are affixed using an adhesive, shrink heat technology, or employing an enlarged (e.g. ball) configuration at the distal end of the control wire that inhibits the distal end from entering the channel  62 . The catheter shafts are typically fabricated from a mixture of low density (LDPE) and high density (HDPE) polyethylenes, or can be manufactured from a variety of thermoplastic polymers know by those skilled in the art in making medical catheters. The flexible balloon catheter and the guidewire lumen are dimensionally and characteristically similar with that discussed previously for the first embodiment.  
         [0038]    [0038]FIG. 4 is a cross-sectional illustration of a distal end of the balloon sheath embodiment that employs control wires engaged to the distal side of the balloon with the balloon in an expanded configuration. Shown on FIG. 4 is a third embodiment  46  of the balloon sheath whereby the catheter/spherical balloon assembly employs a means to attach one or more control wires  54  to the distal end of the balloon. The distally attached control wires  54  extend along the length of the catheter and are contained with channels  62  shown in FIG. 7. The channels  62  terminate at the distal end of the flexible balloon  56 . The distally attached control wires  54  engage the end of the channel and are affixed using an adhesive, shrink heat technology, or employing an enlarged (e.g. ball) configuration at the distal end of the control wire that inhibits the distal end from entering the channel  62 . The catheter shafts are typically fabricated from a mixture of low density (LDPE) and high density (HDPE) polyethylenes, or can be manufactured from a variety of thermoplastic polymers know by those skilled in the art in making medical catheters. The flexible balloon catheter and the guidewire lumen are dimensionally and characteristically similar with that discussed previously for the first embodiment.  
         [0039]    [0039]FIG. 5 is a cross-sectional view taken along the line  5 - 5  of FIG. 2 and shows the coaxial design and relative positioning of the proximal catheter shaft, demonstrating the outer shaft tubing material  40 , the inflation/deflation lumen  34 , inner shaft tubing material  42  and guidewire lumen  38 .  
         [0040]    Likewise, FIG. 6 is a cross-sectional view taken along the line  6 - 6  of FIG. 2 and shows the coaxial design and relative positioning of the distal catheter shaft, demonstrating the outer shaft tubing material  32 , the inflation/deflation lumen  34 , inner shaft tubing material  42  and guidewire lumen  38 .  
         [0041]    [0041]FIG. 7 is a cross-sectional view taken along the line  7 - 7  of FIG. 3 and line  7 - 7  of FIG. 4 and demonstrates the multiple lumen tubing  60  that includes channels  62  for containing the embodiments having control wires  52 ,  54  for engaging the flexible balloon. This Figure shows four channels located at ninety degrees. It is contemplated by the Applicants that one to six wires may be employed to facilitate pivotal movement of the flexible balloon. In its simplest form, a control wire is pulled away from the armed adapter on the proximal end of the catheter in a direction that is substantially parallel to the longitudinal axis. The tensioned control wire that is attached to the balloon will compel the balloon to pivot and rotate in the direction of the tensioned control wire. If the control wire located in the 12 o&#39;clock position of FIG. 7 is tensioned, the balloon will tend to bend towards this 12 o&#39;clock position. The lumen of channel  62  is generally 0.002″ to 0.010″ in diameter, with a preferable range of 0.003″ to 0.005″. The control wires  52 ,  54  are generally smaller than the lumen of the channel by approximately 0.002″, therefore, the control wire  52 ,  54  is generally 0.001″ to 0.008″ in diameter, with a preferable range of 0.001″ to 0.003″. Control wires must have sufficient tensional (pull) strength to not break when subjected to a range of tensional forces. Therefore, the control wires  52 ,  54  are fabricated from a metallic material such as stainless steel. Other metallic and polymeric materials with adequate tensional (pull) strength could suffice for the control wire material. It is also contemplated by the Applicants, but not shown, that the channels and corresponding control wires could be configured in another shape, such as square or rectangle.  
         [0042]    Now referring to FIG. 8 which is a cross-sectional illustration of the hydraulic guidewire  68  of the present invention system. The hydraulic guidewire  68  includes a proximal stainless steel hypotube structure  80  that terminates at approximately the last 35 centimeters as a spring coil  76  encased with a polymeric jacket  72  to form a composite structure  73 . Attached to the proximal end of the guidewire is an adapter with at least one extension. In FIG. 8, the two arm adapter has a hydraulic fitting  86  with a hydraulic lumen  88  and a removable core fitting  84 . One type of spring coil  76  can be a 0.002″×0.004″ rectangle fabricated from a spring stainless steel. The polymeric jacket is typically a Pebax material that is shrink fitted over the spring coil  76 . Other polymeric materials, such as Teflon, HDPE/LDPE, or urethanes can be employed. The junction  81  between the hypotube  80  and the composite structure  73  is secured by techniques known in the prior art, such as over lapping one section over another and adhering by brazing or adhesives. The lumen of the hydraulic guidewire is generally 0.006″ to 0.010″ in diameter, preferably with a range of 0.008″ to 0.010″ in diameter. The end of the guidewire is tapered and terminates with an aperture  77  that is substantially aligned with the longitudinal axis of the hydraulic guidewire. Fluid (saline, contrast) infused from the proximal hydraulic fitting  86  can be a steady stream or pulsed through the lumen  71  with sufficient pressure to exit this tapered end  78  and out the aperture  77 . Together with mechanical force, the pulsed liquid will assist the guidewire in penetrating the total occlusion.  
         [0043]    Furthermore, the hydraulic guidewire  68  can be fitted with one or more apertures  74  facing radially from the longitudinal axis of the guidewire. The apertures  74  will perform as thrusters assisting the guidewire to center within a vessel lumen. When fluid is infused from the proximal hydraulic fitting  86  with sufficient pressure through the lumen  71  to exit one or more of these apertures  74 , they can serve to facilitate centering the guidewire.  
         [0044]    The hydraulic guidewire  68  also includes a removable core  70  that is used initially to provide internal support to the guidewire  68 . The removable core  70  can be relocated at various points along the distal end to vary the stiffness and flexibility for given clinical requirements. Furthermore the removable core  70  can be completely retracted when hydraulic fluids are being infused through the guidewire lumen  71 .  
         [0045]    [0045]FIG. 9 is a cross-sectional view taken along the line  9 - 9  of FIG. 8 and shows the design and relative positioning of the removable core  70 , the spring coil  76  and the guidewire jacket  72 .  
         [0046]    [0046]FIG. 10 is a cross-sectional illustration of the exchange sheath of the present invention system. The exchange sheath  90  includes a spring coil  92  encased with a polymeric jacket  94  to form an exchange sheath composite structure  95 . One type of spring coil  76  can be a 0.002″×0.004″ rectangle fabricated from a spring stainless steel. The polymeric jacket is typically a Pebax material that is shrink fitted over the spring coil  76 . Other polymeric materials, such as Teflon, HDPE/LDPE, or urethanes can be employed. The lumen of the exchange sheath is generally 0.018″ to 0.026″ in diameter, preferably with a range of 0.020″ to 0.022″ in diameter. The end of the exchange sheath is tapered. The exchange sheath  90  is designed to advance over the hydraulic guidewire  68 , penetrating the guidewire-crossed total occlusion, further dilating and dottering the channel or lumen first created by the hydraulic guidewire. After the exchange sheath is advanced through the occlusion, it can be retracted, or the guidewire can be exchanged and then the exchange sheath removed. Then either the hydraulic guidewire, a previously placed standard guidewire, or a new guidewire can be available for use in positioning interventional and diagnostic catheters across the total occlusion. Most commonly, interventional catheters will be positioned across the total occlusion for treating the occlusion. Exemplary interventional catheters include angioplasty balloon catheters, rotational atherectomy catheters, directional atherectomy catheters, stent-placement catheters, and the like.  
         [0047]    [0047]FIG. 11 is a cross-sectional view taken along the line  11 - 11  of FIG. 10 and shows the design and relative positioning of the spring coil  92  and the exchange sheath jacket  94 .  
         [0048]    [0048]FIG. 12 is a cross-sectional view of a prior standard guidewire where the guidewire has entered the subintimal space and penetrated the vessel wall  104 . The medical equipment currently in use has a fundamental flaw because it tends to track the outside radius of the vessel lumen  110 . Once the guidewire has penetrated the vessel wall  108 , it is very difficult to retract the guidewire and direct it towards and through the total occlusion  106 . Furthermore, the penetrated vessel wall may need further interventions to minimize blood perfusion.  
         [0049]    [0049]FIG. 13 is a cross-sectional view of a prior standard guidewire non-centered into the vessel lumen and entering and advancing into the subintimal space within the medial layer. Medical equipment currently in use has a fundamental flaw in that it tends to track the outside radius of the vessel lumen  110 . Once the guidewire  122  has entered the subintimal space of the vessel wall  104 , it is very difficult to retract the guidewire and direct it towards and through the total occlusion  106 . This result is very undesirable and potentially dangerous to the clinical outcome.  
         [0050]    [0050]FIG. 14 is a cross-sectional view of a prior standard guidewire prolapsing  132  within a vessel lumen. Even when current technology medical equipment is shaped to facilitate finding the center of the total occlusion, the guidewire can get caught in thrombus or buckle against the occlusion. Further attempts to advance the guidewire may cause the tip to curl over and prolapse over itself. Again, this result is very undesirable and potentially dangerous because it can result in perforation of the artery.  
         [0051]    [0051]FIG. 15 is a cross-sectional view of the present invention hydraulic guidewire  68  within a vessel lumen and in position just proximal of the total occlusion  106  for treatment.  
         [0052]    [0052]FIG. 16 is a cross-sectional view of the present invention balloon sheath in an expanded configuration  50 ,  56  with the hydraulic guidewire  68  just proximal to the total occlusion. The balloon sheath is supporting the guidewire  68  to become substantially centered within the vessel lumen. Furthermore, the balloon sheath with proximally attached control wires  44  or balloon sheath with distally attached control wires  46  can be controlled remotely from the proximal end of the catheter to further enhance the centering position of the guidewire.  
         [0053]    [0053]FIG. 17 is a cross-sectional view of the present invention balloon sheath in an expanded configuration  50 ,  56  with the hydraulic guidewire  68  employing various apertures  74  to further center the guidewire and penetrate the total occlusion  106 . As can be seen by the present invention system and methods, the balloon sheath and hydraulic guidewire  68  are designed to center the guidewire within the vessel lumen and facilitate the penetration through the total occlusion  106 . Hydraulic pulses  152  emanating from the distal tip are assisting the guidewire  68  to penetrate the occlusion  106  and create a channel. Fluids being forced through the radially directed apertures  74  are further causing the hydraulic guidewire  68  to be centered with the vessel lumen. Once the hydraulic guidewire  68  has passed through the total occlusion and created a channel, the balloon sheath can be removed and the exchange sheath can be threaded over the hydraulic guidewire to further dilate and dotter the channel. Access is now available for other interventional devices to further treat the occlusion and achieve a clinically desirably result.