Abstract:
A method including introducing a catheter between two layers of a wall of a body lumen, the catheter including a balloon disposed at a distal end thereof, the catheter being formed with a first lumen through the balloon for passing therethrough a guidewire and a second lumen for inflation and deflation of the balloon, and expanding the balloon so that a distal portion of the first lumen that passes through the balloon is bent with respect to a portion of the first lumen proximal to the balloon and is directed towards the body lumen.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 USC §119 to U.S. Provisional Patent Application 60/920,561, filed Mar. 29, 2007, U.S. Provisional Patent Application 60/994,732, filed Sep. 24, 2007, and U.S. Provisional Patent Application 60/997,099, filed Oct. 2, 2007, the disclosures of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to devices and methods for reentry from one lumen into another lumen, such as but not limited to, reentry into a true lumen of a blood vessel from the extraluminal or sub-intimal space of the vessel. 
       BACKGROUND OF THE INVENTION 
       [0003]    Chronic Total Occlusion (CTO) is an arterial vessel blockage (typically of plaque) that obstructs blood flow. CTO can occur both in coronary and peripheral arteries, and generally results from the same underlying cause—atherosclerosis. 
         [0004]    One of the main difficulties in crossing a total occlusion is that the clinician does not know exactly how hard the plaque is until steering a guidewire to the occlusion. If the occlusion is relatively new, the plaque is likely to be soft enough and the guidewire may penetrate the plaque. However, after several weeks or months, the occlusion becomes fibrotic and calcified and the plaque becomes much harder, rendering guidewire crossing of the occlusion difficult if not impossible. Failure to cross the obstruction is the primary failure mode for CTO recanalization. 
         [0005]    Another problem is that the CTO blocks contrast agents from flowing through the artery past the obstruction, preventing use of fluoroscopy to guide the guidewire. This increases the risk of perforating or dissecting the vessel, and may possibly increase the risk of tamponade—blood leaking out of the artery around the heart or peripheral organ. Even crossing a partially occluded blood vessel, especially long and curved occlusions, can be difficult and time consuming. 
         [0006]    As is well known in anatomy, arteries generally have three coats or layers: an internal or endothelial coat ( tunica intima  of Kölliker); a middle or muscular coat ( tunica media ); and an external or connective-tissue coat ( tunica adventitia ). The two inner coats together are easily separated from the external adventitial layer, and the two inner coats are sometimes referred together as the intimal layer rather than the medial and intimal layers. It is known in the art that during an attempt to get past an occlusion with a guidewire, the guidewire sometimes inadvertently penetrates into the subintimal space between the intimal layer and the adventitial layer of the blood vessel as it attempts to cross the occlusion. Once in the subintimal space, it is very difficult and in many cases impossible to direct the guidewire back into the blood vessel true lumen beyond the occlusion. 
         [0007]    However, techniques have been developed for entering the subintimal space on purpose and reentering the true lumen after the occlusion. This so-called subintimal recanalization can be a useful procedure, especially when using drug eluting stents, and is widely used. One of the advantages of subintimal recanalization is that a dissection of the subintimal space is more likely to produce a smooth lumen and improved blood flow than a lumen produced by plowing through calcified plaque. However, technical failure occurs in about 30% of patients undergoing percutaneous intentional extraluminal recanalization, mostly due to the inability to reenter the distal true lumen. 
         [0008]    If during percutaneous extraluminal recanalization, the true lumen cannot be reentered with guidewire manipulation, a true lumen reentry device must be used. Currently there are two specially designed reentry devices in the market. 
         [0009]    The pioneer reentry catheter (from Medtronic, Santa Rosa, Calif., US) is a 7 Fr. intravascular ultrasound (IVUS) device that is placed in the dissection beyond the occlusion. The IVUS image provides an image of the vessel wall. The catheter is constructed with a monorail lumen for delivery of the device over a 0.014 inch wire, and a second wire lumen through the end of the catheter, which ends in a curved nitinol needle that can retract into the catheter near the distal end. The needle is deployed by sliding it out of a distal port at the side of the catheter just proximal to the IVUS transducer. The IVUS device is used to ultrasonically guide, turn and manipulate the curved needle to arrive at the correct radial orientation for reentry into the true lumen. 
         [0010]    The Outback LTD reentry catheter (Cordis, Miami Lakes, Fla., US) is a 6 Fr. catheter with a retractable nitinol curved needle at the distal end. The needle is straight when withdrawn in the catheter. When pushed forward, the needle is restored to its curved shape and can penetrate the medial and intimal layers to reenter the true lumen. The rotational orientation of needle deployment is provided by fluoroscopic guiding markers on the catheter. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention seeks to provide novel devices and methods for lumen reentry, as is described more in detail hereinbelow. 
         [0012]    The present invention has many applications, such as but not limited to, true lumen reentry in PTA (percutaneous transluminal angioplasty), PTCA (percutaneous transluminal coronary angioplasty), and any other percutaneous or non-percutaneous placement of a catheter between two adjacent layers of vessels, arteries, soft tissue, or any other human tissue. 
         [0013]    In one embodiment of the invention, a device and method are provided for reentry into a true lumen of a blood vessel from the extraluminal or sub-intimal space of the vessel. The invention eliminates the need for rotational direction by an imaging system or for curved needles as in the prior art. Instead, in one embodiment of the invention that includes a catheter and guidewire, the lumen reentry device automatically bends the catheter after the occlusion so that the catheter distal end is directed in the direction of the true lumen so that the guidewire can penetrate back into the true lumen. 
         [0014]    The invention assists the clinician (e.g., cardiologist, radiologist, vascular surgeons or any other medical doctor who engages in angioplasty procedures) in treating total occlusions, and can be used to cross both new and soft plaque and old and hard plaque. 
         [0015]    In one non-limiting embodiment of the invention, the method includes 1) inserting a guidewire in a balloon catheter into the proximal vessel true lumen, 2) dissecting the vessel with the guidewire near the proximal end of the occlusion, 3) moving the guidewire through the subintimal space of the blood vessel distally past the occlusion, 4) moving the balloon catheter distally past the occlusion over the guidewire, 5) moving the guidewire proximally to the balloon, and deploying (inflating) a balloon that deflects the intimal layer away from the adventitial layer of the blood vessel and bends the catheter towards the inner volume of the true lumen; and 6) penetrating the intimal layer back into the true lumen and reentering the true lumen with the guidewire. The method may further include performing balloon angioplasty through the recanalized lumen, and deploying a stent. The stent is typically long enough to start in the proximal true lumen and end in the distal true lumen. 
         [0016]    There is provided in accordance with an embodiment of the invention a lumen reentry device including a catheter including a balloon disposed at a distal end thereof, the catheter being formed with a first lumen through the balloon for passing therethrough a guidewire and a second lumen for inflation and deflation of the balloon, the catheter and the balloon being sized and shaped for entry between two layers of a wall of a body lumen, wherein upon expansion of the balloon when placed between the layers, a distal portion of the first lumen that passes through the balloon is bent with respect to a portion of the first lumen proximal to the balloon and is directed towards the body lumen. The balloon may include an inverted distal neck. 
         [0017]    In one non-limiting embodiment of the invention, a guidewire passes through the first lumen and is adapted to pierce at least one of the layers to enter the body lumen. It is noted that the “guidewire” piercing the layer or layers encompasses not just the guidewire but any stylet, needle or wire capable of puncturing through to the lumen. 
         [0018]    In another non-limiting embodiment of the invention, a hypo-tube needle is disposed in the first lumen and a guidewire passes through an internal cavity of the needle, a distal end of the needle being adapted to pierce at least one of the layers to enter the body lumen. 
         [0019]    In one non-limiting embodiment of the invention, a diameter of the balloon is not more than a diameter of the body lumen. 
         [0020]    In one non-limiting embodiment of the invention, a length of the balloon is not more than the diameter of the balloon. Alternatively, the length of the balloon can be double the diameter of the balloon. Other lengths are also possible. 
         [0021]    In one non-limiting embodiment of the invention, the catheter is formed with a pivoting portion proximal to the distal portion upon which the balloon is disposed. The pivoting portion may include a weakened section having a smaller wall thickness than other portions of the catheter. Alternatively, the pivoting portion includes a portion made of a flexible material. Alternatively, the pivoting portion includes a joint. Alternatively, the pivoting portion includes a section which is softer and easier to bend than the rest of the catheter. 
         [0022]    In one non-limiting embodiment of the invention, the catheter is slidingly disposed in a sheath and the distal portion of the catheter is bendable at a juncture with a distal end of the sheath. 
         [0023]    In one non-limiting embodiment of the invention, a diameter of the balloon is equal to or slightly larger than a diameter of the body lumen. 
         [0024]    In one non-limiting embodiment of the invention, the device further includes a second balloon mounted on the catheter proximal to the balloon, the second balloon being inflatable through a third lumen formed in the catheter. 
         [0025]    It is noted that the invention is not limited in the number of balloons and lumens. For example, the device can include four lumens (two for inflating balloons, one for passing a guidewire, and another one for injecting a contrast agent). Another example is a three lumen device (one for inflating a balloon, one for passing a guidewire, and one for injecting a contrast agent). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: 
           [0027]      FIG. 1  is a simplified, partially sectional, schematic illustration of a lumen reentry device, constructed and operative in accordance with an embodiment of the present invention; 
           [0028]      FIG. 2  is another simplified, partially sectional, schematic illustration of the lumen reentry device of  FIG. 1 , including a hypo-tube needle disposed in a catheter; 
           [0029]      FIGS. 3 and 4  are simplified, partially sectional, schematic illustrations of the lumen reentry device of  FIG. 1  introduced in a blood vessel subintimal space, in accordance with an embodiment of the present invention, respectively before and after balloon inflation; 
           [0030]      FIG. 5  is a simplified, partially sectional, schematic illustration of a lumen reentry device with a covering sheath, constructed and operative in accordance with another embodiment of the present invention; 
           [0031]      FIG. 6  is a simplified, partially sectional, schematic illustration of the lumen reentry device of  FIG. 5  introduced in the subintimal space of a blood vessel, with a hypo-tube penetrating through the internal blood vessel wall layer, after moving the covering sheath proximally backwards and after balloon inflation; 
           [0032]      FIGS. 7A and 7B  are simplified schematic illustrations of a non-inverted distal balloon neck ( FIG. 7A ) and a balloon with such a neck mounted on a catheter ( FIG. 7B ); 
           [0033]      FIGS. 7C and 7D  are simplified schematic illustrations of an inverted distal balloon neck ( FIG. 7C ) and a balloon with such a neck mounted on a catheter ( FIG. 7D ), in accordance with an embodiment of the present invention; 
           [0034]      FIG. 8  is a simplified, partially sectional, schematic illustration of a lumen reentry device in the subintimal space of a blood vessel after balloon inflation, showing that if the balloon has a protruded, non-inverted distal neck it may fail to orient the device properly for puncturing the blood vessel for reentry into the true lumen; 
           [0035]      FIG. 9  is a simplified, partially sectional, schematic illustration of a lumen reentry device, constructed and operative in accordance with yet another embodiment of the present invention, introduced in the subintimal space of a blood vessel, using a long angioplasty balloon having an inverted distal neck and no neck distal protrusion; 
           [0036]      FIG. 10  is a simplified, partially sectional, schematic illustration of a lumen reentry device, constructed and operative in accordance with still another embodiment of the present invention, and including a reentry balloon and a PTA balloon on the same catheter; and 
           [0037]      FIG. 11  is a simplified, partially sectional, schematic illustration of the lumen reentry device of  FIG. 10  introduced in the subintimal space of a blood vessel, and after balloon inflation. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0038]    Reference is now made to  FIG. 1 , which illustrates a lumen reentry device  1 , constructed and operative in accordance with an embodiment of the present invention. Device  1  includes a catheter  10  which has a balloon  11  disposed at a distal end thereof. The distal end of catheter  10  protrudes only slightly, or does not protrude at all, beyond balloon  11 . The significance of this will be explained further below. Catheter  10  is formed with a first lumen  12  through balloon  11  for passing therethrough a guidewire  27 , and a second lumen  13  for inflation and deflation of balloon  11 . 
         [0039]    Catheter  10  may be fabricated from polyethylene, polyurethane, PEBAX (polyether block amide from Arkema), nylon or other polymers known in the art. The catheter shaft can also be made from polymers reinforced with metal wires braid or springs, as is known in the art. 
         [0040]    Balloon  11  may be fabricated from polyurethane, silicon, PET (polyethylene terephthalate), and other suitable polymers known in the art. 
         [0041]    Reference is now made to  FIG. 3 , which illustrates lumen reentry device  1  introduced in a true lumen  8  and then through a dissection  2 , typically between an internal intimal layer  3  (perhaps both the medial layer together with the intimal layer) and an external adventitial layer  4  of a blood vessel  5 , over a guidewire  27  (shown for clarity only at the proximal end of catheter  10 ). Balloon  11  has been passed beyond the distal end of an occlusion  6 . 
         [0042]    In the illustrated embodiment, balloon  11  is a small conical balloon. The balloon diameter is preferably similar or smaller than the diameter of the true lumen  8  of blood vessel  5 . Balloon  11  can also have a round ball (spherical) shape or other similar elliptical shapes, wherein its diameter is a few times the diameter of catheter  10 , but not more than the diameter of true lumen  8 . In the illustrated embodiment, the length of balloon  11  is relative short compared to common angioplasty balloons, usually not more than twice its diameter. 
         [0043]    When catheter  10  and balloon  11  are in place as shown in  FIG. 3 , balloon  11  is then inflated, e.g., to a pressure of several atmospheres, as shown in  FIG. 4 . The balloon inflation creates a space  7  (void or passageway) by pushing the surrounding tissues, that is, intimal layer  3  and external adventitial layer  4 . Balloon  11  is located subintimally between layers  3  and  4 , and the high pressure inflation produces a relatively high force on the two tissue layers  3  and  4 . The forces cause the internal intimal layer  3  to yield first, bending or folding towards the adjacent true lumen  8 , rather than causing the external adventitial layer  4  to stretch or become extended. This is because the force needed to stretch the tougher external adventitial layer  4  is much higher than the force needed to fold or bend the more flexible internal intimal layer  3 , especially since the internal intimal layer  3  is folding toward the true lumen  8 . 
         [0044]    Folding of the internal intimal layer  3 , with minimal or no movement from the external adventitial layer  4 , causes the distal end of catheter  10  to bend towards the true lumen  8 . This automatically points the distal end of catheter  10  and guidewire  27  (shown also at the distal end of catheter  10  in  FIG. 4 ) correctly towards the true lumen  8  for punching back through the internal intimal layer  3  into the true lumen  8 , without any need for an imaging system for rotational orientation. 
         [0045]    The penetration into the true lumen  8  through the internal blood vessel layer  3  can be done simply and directly with guidewire  27 . Afterwards catheter  10  can be withdrawn from the patient to leave guidewire  27  in place, such as for placing a stent (not shown). It is noted that the same guidewire  27  can be used for catheter  10  and for introducing the stent, which significantly facilitates the clinician&#39;s work. 
         [0046]    Reference is now made to  FIG. 2 , which illustrates an alternative way of puncturing the internal layer  3  for reentry into the true lumen  8 . In this embodiment, a flexible hypo-tube needle  14  is disposed in first lumen  12  of catheter  10 . Hypo tube  14 , preferably made from a shape memory alloy such as nitinol, may be pre-cut to a needle shape at its distal end  15 . 
         [0047]    The embodiment of  FIG. 2  is used the same way as the embodiment of  FIG. 1 , except that in the embodiment of  FIG. 2 , after balloon inflation, hypo-tube needle  14  is used to puncture internal intimal layer  3  to penetrate back into the true lumen  8 . Guidewire  27  may then be introduced through an internal cavity  16  of needle  14  into the true lumen  8 . Afterwards needle  14  may be retracted into catheter  10 , and catheter  10  may be withdrawn from the patient, leaving guidewire  27  in place, as described above. The bending angle is a function of the catheter point of bending at the plaque distal end and the balloon diameter 
         [0048]    As mentioned above, the distal end of catheter  10  protrudes only slightly, or does not protrude at all, beyond balloon  11 . The significance of this is now explained with reference to  FIGS. 7A-8 . 
         [0049]      FIGS. 7A and 7B  illustrate a balloon having a balloon body  11 A and non-inverted distal and proximal necks  11 B and  11 C, respectively.  FIG. 7B  shows such a balloon mounted on catheter  10 . 
         [0050]    In contrast,  FIGS. 7C and 7D  illustrate the balloon  11  of the present invention with distal and proximal necks  11 D and  11 E, respectively. Distal neck  11 D is inverted into the inner space of balloon  11 . The inverse or inverted distal neck  11 D of balloon  11  can be manufactured directly as an inverted neck or can be made non-inverted and then inverted before bonding to catheter  10 . Proximal neck  11 E can be made and bonded in a standard way. 
         [0051]    Reference is now made to  FIG. 8 , which illustrates the lumen reentry device with a balloon having the non-inverted distal neck  11 A in the subintimal space of a blood vessel after balloon inflation. It is seen that the non-inverted distal neck  11 A can bend and point away from the true lumen  8 , thereby failing to orient the device properly for puncturing the blood vessel for reentry into the true lumen  8 . 
         [0052]    Reference is made again to  FIG. 4 . In another embodiment of the present invention, catheter  10  may be formed with a pivoting portion  18  proximal to a distal portion  26  of catheter  10  upon which balloon  11  is disposed. Pivoting portion  18  may be formed in several ways. For example, pivoting portion  18  may comprise a weakened section having a smaller wall thickness, or a portion made of a flexible material, or a joint, or a section without metal wires, springs or braids, making it softer and easy to bend or rotate with minimal resistance from the rest of the catheter shaft. The position of pivoting portion  18 , together with the balloon diameter, defines the catheter distal end bend angle. 
         [0053]    Reference is now made to  FIGS. 5 and 6 , which illustrate lumen reentry device  1  with a covering sheath  17 , constructed and operative in accordance with another embodiment of the present invention. Sheath  17  may be fabricated from polyurethane, PET, PTFE or other suitable polymers known in the art. As seen in  FIG. 6 , catheter  10  and sheath  17  are inserted together over guidewire  27 . After being placed distally beyond occlusion  6 , sheath  17  can be pulled slightly backwards (proximally) to a pre-determined distance and distal portion  26  of catheter  10  bends at the juncture with the distal end of sheath  17 . The bending angle is a function of the catheter point of bending at the sheath distal end and the balloon diameter. 
         [0054]    Reference is now made to  FIG. 9 , which illustrates a lumen reentry device, constructed and operative in accordance with yet another embodiment of the present invention. In this embodiment, a long balloon  20 , similar to balloons used in angioplasty procedures, but having inverted distal neck  20 A as described before, can be used for reentry. Proximal neck  20 B can be non-inverted as described before. If the diameter of balloon  20  is equal to or slightly larger than the blood vessel internal diameter, expansion of balloon  20  forces the internal layer  3  to fully collapse towards the opposite blood vessel wall. A guidewire or straight needle can then be used to punch the blood vessel internal layer  3  into the true lumen  8 , as described above. Pivoting portion  18  of catheter  10  can be used proximally to balloon  20  to allow rotating or bending balloon  20 . 
         [0055]    Reference is now made to  FIG. 10 , which illustrates a lumen reentry device  30 , constructed and operative in accordance with still another embodiment of the present invention. 
         [0056]    Device  30  includes a catheter  32  which has a balloon  34  disposed at a distal end thereof. The distal end of catheter  32  protrudes only slightly, or does not protrude at all, beyond balloon  34 , as in the previous embodiments. Accordingly the distal neck of balloon  34  is inverted. Catheter  32  includes an external tube  33  in which an internal tube  35  is disposed. The distal neck of balloon  34  may be bonded or otherwise attached to internal tube  35 , and its proximal neck to external tube  33 . Internal tube  35  is smaller, and preferably softer or more flexible than external tube  33 , thereby creating a pivotal point for balloon  34  to bend when inflated. Internal tube  35  is formed with a first lumen  36  for passing therethrough a guidewire  37 . A second lumen  38  is formed between the internal and external tubes  35  and  33  for inflation and deflation of balloon  34 . 
         [0057]    Balloon  34  is a reentry balloon and its use is as described above. In addition, proximal to balloon  34 , a second balloon  40  is mounted on the same catheter  32 . Second balloon  40  is a PTA balloon and may be attached to the external tube  33  of catheter  32  with regular, non-inverted necks. Second balloon  40  may be inflated or deflated via a third lumen  42  formed in the external tube  33  of catheter  32 . 
         [0058]    Reference is now made to  FIG. 11 , which illustrates lumen reentry device  30  introduced in the subintimal space of a blood vessel, and after balloon inflation. The conical shape of balloon  34  helps direct the distal end of catheter  32  towards the true lumen. The second balloon  40  may then be inflated for angioplasty and stent introduction procedures. 
         [0059]    Other variations of the embodiment of device  30  are in the scope of the invention. For example, the device may include two lumens (one for the guidewire and another for the balloon), wherein the balloon lumen can inflate either two separate balloons (PTA and reentry) or one balloon that has two sub-balloons (two “humps”), one for PTA and the other for reentry. 
         [0060]    It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of the features described hereinabove as well as modifications and variations thereof which would occur to a person of skill in the art upon reading the foregoing description and which are not in the prior art.