Abstract:
Devices and methods for the treatment of chronic total occlusions are provided. One disclosed embodiment comprises a method of facilitating treatment via a vascular wall defining a vascular lumen containing an occlusion therein. The method includes providing an intravascular device having a distal portion, inserting the device into the vascular lumen, positioning the distal portion in the vascular wall to at least partially surround the occlusion, and removing at least a portion of the surrounded occlusion from the lumen.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of U.S. patent application Ser. No. 13/214,141, filed Aug. 19, 2011, which is a continuation of U.S. patent application Ser. No. 11/518,431, filed Sep. 11, 2006, now U.S. Pat. No. 8,025,655, which claims the benefit of U.S. Provisional Application No. 60/716,287, filed Sep. 12, 2005, and U.S. Provisional Application No. 60/717,726, filed Sep. 15, 2005. The entire disclosure of each of the above-referenced applications is incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The inventions described herein relate to devices and associated methods for the treatment of chronic total occlusions. More particularly, the inventions described herein relate to devices and methods for crossing chronic total occlusions and subsequently performing balloon angioplasty, stenting, atherectomy, or other endovascular methods for opening occluded blood vessels. 
     BACKGROUND OF THE INVENTION 
     Due to age, high cholesterol and other contributing factors, a large percentage of the population has arterial atherosclerosis that totally occludes portions of the patient&#39;s vasculature and presents significant risks to patient health. For example, in the case of a total occlusion of a coronary artery, the result may be painful angina, loss of cardiac tissue or patient death. In another example, complete occlusion of the femoral and/or popliteal arteries in the leg may result in limb threatening ischemia and limb amputation. 
     Commonly known endovascular devices and techniques are either inefficient (time consuming procedure), have a high risk of perforating a vessel (poor safety) or fail to cross the occlusion (poor efficacy). Physicians currently have difficulty visualizing the native vessel lumen, can not accurately direct endovascular devices toward visualized lumen, or fail to advance devices through the lesion. Bypass surgery is often the preferred treatment for patients with chronic total occlusions, but less invasive techniques would be preferred. 
     SUMMARY OF THE INVENTION 
     To address this and other unmet needs, the present invention provides, in exemplary non-limiting embodiments, devices and methods for the treatment of chronic total occlusions. The disclosed methods and devices are particularly beneficial in crossing coronary total occlusions but may also be useful in other vessels including peripheral arteries and veins. In exemplary embodiments, total occlusions are crossed using methods and devices intended to provide a physician the ability to place a device within the subintimal space, delaminate the connective tissues between layers within the lesion or vessel wall, or remove tissues from the chronic total occlusion or surrounding vessel. 
     In an aspect of the disclosure, a subintimal device may be used to guide conventional devices (for example guide wires, stents, lasers, ultrasonic energy, mechanical dissection, or atherectomy) within the vessel lumen. Additionally, a subintimal device may be used to delaminate vessel wall layers and also may be used to remove tissue from the occlusive lesion or surrounding vessel wall. In one example, the positioning of a subintimal device or the establishment of a delamination plane between intima and medial layers is achieved through the use of a mechanical device that has the ability to infuse a fluid (for example saline). Fluid infusion may serve to apply a hydraulic pressure to the tissues and aid in layer delamination and may also serve to protect the vessel wall from the tip of the subintimal device and reduce the chance of vessel perforation. The infusion of fluid may be controlled by pressure or by volume. 
     Subintimal device placement may be achieved with a subintimal device directing catheter. The catheter may orient a subintimal device so that it passes along the natural delamination plane between intima and media. The catheter may orient the subintimal device in various geometries with respect to the vessel. For example, the subintimal device may be directed substantially parallel with respect to the vessel lumen or in a helical pattern such that the subintimal device encircles the vessel lumen in a coaxial fashion. The subintimal device directing catheter may be an inflatable balloon catheter having proximal and distal ends with two wire lumens. One lumen may accept a conventional guide wire while the second lumen may accept the subintimal device. In an alternative embodiment, the wire directing catheter may be a guide catheter with distal geometry that steers the subintimal device with the appropriate orientation to enter the subintimal space. 
     In an additional disclosure, a subintimal device intended to mechanically delaminate tissue layers may use a device that is inserted into the subintimal space in a first collapsed configuration and is released or actuated into a second expanded configuration. The device may then be withdrawn or manipulated to propagate the area of delamination. 
     An additional aspect of the disclosure may allow the physician to remove tissues from the lesion or vessel wall. In one embodiment, a subintimal device is circumferentially collapsed around the total occlusion. Tissue removal is performed through simple device withdrawal or through a procedure that first cuts connective tissues (i.e. the intimal layer proximal and distal of the lesion) and then removes the targeted tissue. In another embodiment, a tissue removal device is passed through the lesion within the native vessel lumen. The targeted tissues may be mechanically engaged and removed through device withdrawal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       It is to be understood that both the foregoing summary and the following detailed description are exemplary. Together with the following detailed description, the drawings illustrate exemplary embodiments and serve to explain certain principles. In the drawings, 
         FIG. 1  shows an illustration of a heart showing a coronary artery that contains a chronic total occlusion; 
         FIG. 2  is a schematic representation of a coronary artery showing the intimal, medial and adventitial layers; 
         FIG. 3  is a partial sectional view of a subintimal device directing balloon catheter embodiment with fluid infusion through the subintimal device lumen within the device directing catheter; 
         FIG. 4  is a partial sectional view of a subintimal device directing balloon catheter embodiment with fluid infusion through the subintimal device; 
         FIG. 5  is a partial sectional view of an additional subintimal device directing guiding catheter embodiment with fluid infusion through the subintimal device; 
         FIGS. 6A  and B are partial sectional views of a expandable delamination catheter; 
         FIGS. 7  A-D are partial sectional views of a circumferential subintimal tissue removal device; 
         FIGS. 8A-C  are an example of subintimal device construction; and 
         FIGS. 9A  and B are partial sectional views of an intraluminal rotational engagement tissue removal device. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention. 
     Referring to  FIG. 1 , a diseased heart  100  includes a chronic total occlusion  101  of a coronary artery  102 .  FIG. 2  shows coronary artery  102  with intimal layer  200  (for sake of clarity, the multi layer intima is shown as a single homogenous layer). Concentrically outward of the intima is the medial layer  201  (which also is comprised of more than one layer but is shown as a single layer). The transition between the external most portion of the intima and the internal most portion of the media is referred to as the subintimal space. The outermost layer of the artery is the adventitia  202 . 
     In an aspect of the disclosure, a subintimal device may be used to guide conventional devices (for example guide wires, stents, lasers, ultrasonic energy, mechanical dissection, or atherectomy) within the vessel lumen. Additionally, a subintimal device may be used to delaminate vessel wall layers and also may be used to remove tissue from the occlusive lesion or surrounding vessel wall. In one embodiment,  FIG. 3  shows a subintimal device directing catheter is  300  with its distal balloon  301  that has been advanced over a conventional guide wire  302  and inflated proximal to chronic total occlusion  101 . For the sake of clarity,  FIG. 3  shows a subintimal device path that is substantially parallel to the vessel lumen, but other orientations (i.e. helical) may also be considered. Subintimal device lumen  303  is positioned adjacent to the intimal layer  200  and subintimal device  304  has been advanced as to perforate the subintimal layer. A fluid source (i.e. syringe)  305  is in fluid communication with subintimal device lumen  303  through infusion lumen  306 . Fluid may flow from the fluid source  305  through the subintimal device lumen  303  under a controlled pressure or a controlled volume. The infused fluid may enter the subintimal space  307  directly from the subintimal device lumen  303  or from the volume  308  defined by the distal end of the balloon  301  and the proximal edge of the lesion  101 .  FIG. 4  shows an alternative fluid infusion path where fluid source  305  is in fluid communication with a lumen within the subintimal device  304 .  FIG. 5  shows an alternative subintimal device directing guide catheter  500  where the distal end  501  has a predefined shape or the distal end has an actuating element that allows manipulation by the physician intra-operatively. 
     Another aspect of the disclosure may place a subintimal device within the subintimal space in a first collapsed configuration and releases or actuates the subintimal device to a second expanded configuration. The device may then be withdrawn or manipulated to propagate the subintimal dissection. In one embodiment,  FIG. 6A  shows a subintimal device with internal expandable element  600  that contains one or more expanding elements  601  contained in exterior sheath  602 .  FIG. 6B  shows exterior sheath  602  in a retracted position allowing expanding elements  601  to elastically expand. The subintimal device is intended to be delivered through the aforementioned subintimal device delivery catheters. 
     An additional aspect of the disclosure may allow the physician to remove tissues from the lesion or vessel wall.  FIG. 7A  shows an embodiment where subintimal device directing balloon catheter is inflated within coronary artery  102  just proximal to chronic total occlusion  101 . Subintimal device  304  is partially delivered around chronic total occlusion  102  coaxially outside the intimal layer  200  and coaxially inside medial layer  201  in a helical pattern.  FIG. 7B  shows a subintimal device capture catheter  702  positioned across the chronic total occlusion  101  over conventional guide wire  703  and within subintimal device  304 . The distal  704  and proximal  705  ends of the subintimal device  304  have been captured and rotated as to reduce the subintimal device outside diameter and contain the lesion  101  and intima  200  within the coils&#39; internal diameter. The device may be withdrawn through the use of a cutting element. For example,  FIGS. 7C  and D show the advancement of a cutting element  706  in two stages of advancement showing the cutting of intima  200  proximal of the occlusion  707  and intimal distal of the occlusion  708 . 
     An additional aspect of the subintimal device is the construction of the device body. The flexibility and torquability of the device body can affect the physician&#39;s ability to achieve a subintimal path. The subintimal device body may be constructed in part or in to total of a single layer coil with geometric features along the coil length that allow adjacent coils to engage (for example mechanical engagement similar to the teeth of a gear).  FIG. 8A  shows coil  801  closely wound such that the multitude of teeth  802  along the coil edges are in contact such that the peaks of one coil falls within the valleys of the adjacent coil. A conventional coil reacts to an applied torsional load by diametrically expanding or contracting, thus forcing the wire surfaces within a turn of the coil to translate with respect to its neighboring turn. The construction of coil  801  resists the translation of wire surfaces within the coil thus resisting the diametric expansion or contraction (coil deformation). An increased resistance to coil deformation increases the torsional resistance of the device body while the coiled construction provides axial flexibility. An exemplary construction may include a metallic tube where the coil pattern  801  and teeth  802  are cut from the tube diameter using a laser beam.  FIG. 8B  shows subintimal device body  804  that is for example a continuous metallic tube with distal laser cut coil segment  801  and proximal solid tube  803 . Tube materials include but are not limited to stainless steel and nickel titanium. Alternatively, the coil may be wound from a continuous wire. The wire has a cross section that for example has been mechanically deformed (stamped) to form the teeth and allow coil engagement.  FIG. 8C  shows an example of a laser cut tooth pattern from the circumference of a tube that has been shown in a flat configuration for purposes of illustration. 
     In another embodiment, a tissue removal device may be passed through the lesion within the native vessel lumen.  FIG. 9A  shows corkscrew device  900  with exterior sheath  902  engaging occlusion after delamination of the intimal layer  901  has been performed by the aforementioned methods and devices.  FIG. 9B  shows removal of the occlusion and a portion of the intimal layer through axial withdrawal of the corkscrew device. 
     From the foregoing, it will be apparent to those skilled in the art that the present invention provides, in exemplary non-limiting embodiments, devices and methods for the treatment of chronic total occlusions. Further, those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departures in form and detail may be made without departing from the scope and spirit of the present invention as described in the appended claims.