Abstract:
A system for treating occlusions present within a body vessel. The device comprises a plaque-treating device having an elongate shaft and a distal plaque-treating portion adapted to remove hardened plaque from within a body vessel. The device further comprises a multi-balloon positioning catheter with a lumen into and through which lumen the plaque-treating device may be extended, the positioning catheter having at least three inflatable balloons positioned circumferentially about the lumen to controllably stabilize the lumen and its distal opening at a desired location within the body vessel, thus controlling the location of the plaque-treating device when extended from the distal end of the positioning catheter&#39;s lumen.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/606,655, filed Mar. 5, 2012. The disclosure of the prior application is considered part of (and is incorporated by reference in) the disclosure of this application. 
     
    
     TECHNICAL FIELD 
       [0002]    This document relates to treating occlusions within body vessels, for example fully occluded body vessels. 
       BACKGROUND 
       [0003]    Many people suffer from lack of vascular supply, for example to the lower extremities. In fact, in some cases people may have total occlusions of a body vessel, for example in the peripheral arterial system for patients suffering from peripheral arterial disease. Total occlusions may consist of different kinds of substances causing the occlusion within the artery. For example, certain portions of the arterial system may be occluded with soft material or with atheroma. Other areas may have hardened calcific plaque which is not easy to penetrate. 
         [0004]    Various devices are known for treating body vessels containing soft material and hardened calcific plaque. Such devices include rotational atherectomy devices that include a rotational burr element that is able to break up or free hardened plaque formed on a vessel wall. Devices such as guidewires have also been used to push through softer materials contained within the vessel and thereby create a more open passageway within the vessel. Treating vascular occlusions is made challenging when there is variability in the plaque morphology, and when occlusions are located at or near a curvature in a vessel. In some cases, it is possible through imaging techniques for a medical practitioner to visualize the passage that is to be traversed; in other cases the path cannot be visualized clearly. 
       SUMMARY 
       [0005]    This document describes, in one aspect, systems and methods for treating occlusions within body vessels. Generally, such a system includes a lumen-forming device, for example a rotational atherectomy device, having an elongate shaft and a distal plaque-treating portion, for example a burr element, adapted to dislodge hardened plaque from within a body vessel. The system also includes a multi-balloon positioning catheter with a lumen into and through which lumen the plaque-threating device may be extended. The positioning catheter has at least three inflatable balloons positioned circumferentially about the lumen to controllably position the lumen and its distal opening at a desired location and trajectory within the body vessel. As such, the positioning catheter controls the location and trajectory of the plaque-treating device when extended from the distal end of the positioning catheter&#39;s lumen. 
         [0006]    In another aspect, this document describes a method for treating deposits from a body vessel. The method includes introducing a positioning catheter into a body lumen. In this method, the positioning includes a lumen into and through which lumen a deposit-treating device is extendable. The positioning catheter further includes at least three inflatable balloons positioned circumferentially about the positioning catheter lumen. The method also includes controlling an inflation level of each of the at least three circumferentially positioned inflatable balloons to position the lumen and its distal end at the desired location and trajectory within the body vessel, introducing the deposit-treating device into the lumen until its deposit-treating distal portion extends distal of a distal opening of the positioning catheter, and treating deposits from within the vessel using the deposit-treating device. 
         [0007]    The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0008]      FIG. 1  is a diagram of an example system for treating deposits from within a body vessel, wherein in this embodiment the system includes a positioning catheter, a rotational atherectomy device, and an external handle/control system. 
           [0009]      FIGS. 2A and 2B  are, respectively, perspective and cross-sectional diagrams of an example embodiment of a distal portion of a positioning catheter. 
           [0010]      FIG. 3  is cut-away diagram showing an example embodiment of a distal portion of a positioning catheter with a rotational atherectomy device extending through a lumen in the positioning catheter. The figure further illustrates the supply of lubricant (for example, Rotaglide) and/or cooling solution. 
           [0011]      FIGS. 4A and 4B  are, respectively, side view and cross-sectional diagrams of an example embodiment of a distal portion of a rotational atherectomy device, wherein, and shown in hidden lines, the rotational atherectomy device has a central longitudinal guidewire lumen extending through the device for the introduction of a guidewire into and through the rotational atherectomy device. 
           [0012]      FIGS. 5A-5C  are diagrams showing an example method of using the system for treating deposits from within a body vessel. 
           [0013]      FIG. 5D  is a diagram showing an example method of using the system within a curved body vessel. 
           [0014]      FIGS. 6A-C  are diagrams of an example system wherein the positioning catheter has two sets of three inflatable balloons, with one set being distal of the other. 
           [0015]      FIG. 7  is a diagram of the  FIG. 6  embodiment being used in a curved vessel. Like reference symbols in the various drawings indicate like elements. 
       
    
    
     DETAILED DESCRIPTION 
     Systems and Devices Description 
       [0016]    The systems and devices described in this document and shown in the accompanying figures are designed to traverse and treat total occlusions, for example in the peripheral arterial system for patients suffering with peripheral arterial disease. One example patient population that may be served by the systems and devices are people suffering from a lack of vascular supply to the lower extremities. In this example, total occlusions in this patient population may consist of different kinds of substances causing the occlusion within the artery. For example, certain portions of the arterial system may be occluded with soft material such as atheroma. Other areas may contain hardened calcific plaque which is not easy to penetrate. In some embodiments, the systems and devices allow crossing of these peripheral occlusive segments of the arterial system so that recanalization can be performed to allow vascular supply to the lower extremity. Other embodiments of the systems and devices may be applied to other arterial circulations within the body, for example recanalization of occluded arteries in the heart. 
         [0017]      FIGS. 1-4  illustrate one embodiment of an example device  100  that includes one set of three equal-sized inflatable balloons  102  that are positioned around the entire periphery of a positioning catheter  104 . The device  100  can be part of a system, for example, for treating deposits from within a body vessel. Referring to  FIG. 1 , the device  100  includes the three balloons  102 , the positioning catheter  104 , a plaque-treating device (e.g. a rotational atherectomy device  108 ), a guidewire  110 , and an external handle/control system  112 . Other embodiments of the device  100  can include more than three balloons  102  in various arrangements, such as four or more balloons in a proximal set positioned around a circumference of the positioning catheter  104 , and can also include other components in addition to those shown for the device  100 . Further, as described below, there can be multiple proximal sets of balloons  102 . In some implementations, the positioning catheter  104  can be made of a material, such as plastic, metal or other materials, such that the balloons  102  can be effective in positioning the positioning catheter  104  for effective operation by a medical practitioner. 
         [0018]      FIGS. 5A-5C  provides a series of diagrams illustrating how the device  100  shown in  FIGS. 1-4  may be operated to treat an occluded vessel, such as a total occlusion  132 . Importantly, the device  100  provides control that keeps the rotational atherectomy device  108  in the center of a lumen  122  within the device  100 , and prevents the rotational atherectomy device  108  from being deflected axially such that it may be inadvertently directed into a vessel wall  134 , causing damage. The three balloons  102  may be inflated or deflated as a group, or each balloon  102  may be independently controlled, depending on the desired trajectory of the plaque-treating device (e.g., the rotational atherectomy device  108 ) that is desired. Independent control of each of the balloons  102  assists in achieving a proper trajectory of the plaque-treating device when addressing a curve in a vessel. 
         [0019]      FIGS. 2A and 2B  are, respectively, perspective and cross-sectional diagrams of an example embodiment of a distal portion  114  of the positioning catheter  104 . In some implementations, pumps  116  connected to pump ends of inflation lines  118  that are connected at balloon ends to balloons  102 , can be used to variably inflate the balloons  102 . For example, each balloon  102  can be variably inflated to control the position of a tip  124  on the distal portion  114 . 
         [0020]    In some implementations, the device  100  includes a control device adapted to control inflation of the circumferentially positioned inflatable balloons to position the lumen at the desired location within the cross-section of the body vessel. For example, using the control device, a medical practitioner can inflate the balloons  102 , e.g., using the pumps  116  that are included with or connected to the control device. In some implementations, the control device is adapted to provide lubricant  120  into the positioning catheter lumen  122  for supply of the lubricant  120  to the distal plaque-treating portion  114 . 
         [0021]      FIG. 6  illustrates another embodiment of the device  100  that includes two sets of three equal-sized inflatable balloons  102 , wherein each set of three balloons  102  is positioned around the entire periphery of the positioning catheter  104 . This embodiment may have an advantage of providing further control in maintaining the centering of a plaque-treating device (e.g., the rotational atherectomy device  108 ) when addressing a situation where plaque is contained at or near a curvature in a vessel. In this case, all six balloons  102  may be independently controllable. Use of the  FIG. 6  embodiment in this manner is illustrated, for example, in  FIG. 7 . 
         [0022]    In one embodiment applicable at least to treat occlusions of peripheral arteries, a positioning catheter  104  will be of a smaller caliber, for example #4 French to #5 French in size. In addition, the outside of the positioning catheter  104  may be coated with lubricant  120  (e.g., lubricious “glide” coating) to allow easy passage through the occluded segment. The lubricant  120  may be supplied through the lumen  122  in the positioning catheter  104 . 
         [0023]    As shown in the figures, the positioning catheter  104  includes the lumen  122  allowing passage through the positioning catheter  104  of the plaque-treating device, such as the rotational atherectomy device  108  or another device that delivers ultrasonic vibrations or laser energy to a distal portion of the plaque-removal device. The lumen  122  of the positioning catheter  104  may further be sized so that the positioning catheter  104  may allow passage of the rotational atherectomy device  108 , as well as lubricant  120  to bathe the device beyond its distal tip  124 . The lumen  122  of the positioning catheter  104  may also allow passage of the guidewire  110 , for example a 0.035 guidewire. In addition or alternatively, the guidewire  110  may be introduced through a lumen  122  in the rotational atherectomy device  108 . 
         [0024]    The distal portion of the positioning catheter  104  has, in one embodiment, three inflatable balloons  102 . The balloons  102  will serve as a mechanism to allow directional movement of a tip  126  of the rotational atherectomy device  108  within the cross-section of the body lumen  128 , as well as providing a locking mechanism that allows stabilization of the catheter tip just above a total occlusion. 
         [0025]    The three inflatable balloons  102  may be, as shown in the figures, of similar size to one another and positioned around the entire circumference of the lumen  122  of the positioning catheter  104 . In other embodiments, there may be more than three balloons  102 , and they may be sized differently from one another. Each of the positioning balloons  102  may be controlled independently. The balloons  102  will serve as a mechanism to allow directional movement of the tip within the cross-section of the body lumen  122 , as well as providing a locking mechanism that allows stabilization of the catheter tip just above a total occlusion. 
       Methods of Utilization 
       [0026]    In use, the positioning catheter  104  may be passed down an arterial sheath that is placed above a total occlusion. Once the positioning catheter  104  is in position at the site of total occlusion, the guidewire  110  (for example, a 0.035 French guidewire) may be used to loosen soft deposits  142  (see  FIG. 5B ). The medical practitioner may sense the presence of hardened plaque  140  by feel (tactile feedback and interpretation by a skilled operator) when manipulating the guidewire  110  to loosen soft deposits  142 . The positioning catheter  104  may be incrementally moved distally during the procedure, as the medical practitioner works a path distal through the vessel. 
         [0027]    At a location where the presence of hardened plaque  140  is detected, for example by feel, the medical practitioner may advance the positioning catheter  104  to be near the site of the hardened plaque  140  (see  FIG. 5C ), and may equally inflate each of the three balloons  102  in a case where the occlusion is in a relatively straight vessel as shown in  FIG. 5C . After the positioning catheter  104  is so positioned with the three circumferential balloons  102  equally inflated, the guidewire  110  may be pulled proximally (retracted), and the rotational atherectomy device  108  advance out of the distal tip of the positioning catheter  104 . Owing to the equal inflation of the three balloons  102 , the rotational atherectomy device  108  will be centered in the vessel, and will be directed in a straight head-on trajectory. As illustrated in  FIG. 5C , the balloons  102  stabilize the trajectory, and prevent the balloon  102  from deflecting when the rotational atherectomy device  108  comes in contact with hardened plaque  140 , which deflection may cause damage to a vessel wall  134  into which the rotational atherectomy device  108  may become otherwise deflected. 
         [0028]    The rotational atherectomy device  108  can be positioned in a heavily calcified plaque and turned on allowing ablation of the calcific plaque and the creation of a small, for example 1 mm or less, orifice or hole through the calcified plaque. The rotational atherectomy device  108  may be moved forward in small increments using the distal portion of the positioning catheter  104  as well as a 0.035/0.014/0.018 wire that advances through and can operate to guide the rotational atherectomy device  108 . 
         [0029]    At the sites of total occlusion, the device  100  can be turned on without fear of perforation as the tip of the rotational atherectomy device  108  is stabilized by the catheter which is directly above it (the catheter is locked into position by inflating the balloons  102  which oppose the walls of the lumen of the artery  136 ). 
         [0030]    As shown in  FIG. 5D , which shows the system of  FIGS. 1-4  in a curved vessel, it may be desirable in these circumstances to inflate the three balloons  102  to different levels. For example, balloon  102   a  on the inside of the curve may be inflated less than balloons  102   b  on the outside of the curve, or not at all. In this manner, the rotational atherectomy device  108  is no longer positioned within the center of the vessel, but rather is positioned closer to the inside of the curve. As such, given that the potential for a damaging deflection is greater in a curved vessel, such a technique provides further safety from a damaging deflection. 
         [0031]    Referring now to  FIG. 7 , there is shown an example use of the  FIGS. 6A-6C  system in a curved vessel. As shown in  FIG. 7 , the distal set of balloons  102  are inflated such that a balloon  102  on the outside of the curve is inflated to a greater level than a balloon  102  positioned on the inside of the curve. Concurrently, for the proximal set of balloons  102 , a balloon  102  positioned on the inside of the curve is inflated to a greater level than the other balloons  102 . In this manner, the rotational atherectomy device  108  not only achieves a positioning within the vessel that is more toward the inside of the vessel curve than the outside of the vessel curve, but also the rotational atherectomy device  108  is given a trajectory that is oriented around the curve of the vessel. Such a trajectory in a curved vessel may help provide further protection from a potentially damaging deflection of the rotational atherectomy device  108 . 
       Control of the Positioning Catheter 
       [0032]    Control of the positioning catheter  104  may be achieved by use of a control unit that may be provided with the system. The control unit may provide a visual display to the operator through the procedure. The control unit may include actuation mechanisms (such as a joystick, buttons, etc.) that receive inputs from the operator to control the inflatable balloons  102  in a desired manner. The control unit may include a processing component that receives the user input, calculates an appropriate inflation level for each of the balloons  102 , and provides an output signal to actuation mechanisms that inflate or deflate each of the balloons  102  to the appropriate calculated level. 
       Additional Features of an Example Rotational Atherectomy Device 
       [0033]    The shaft of the rotational atherectomy device  108  may be strengthened so as not to buckle in its distal 2 cm. The rotational atherectomy device  108  may have a cutting tip estimated to be one-tenth of a millimeter in diameter. The forward half of the rotational atherectomy device  108  may be covered with industrial diamonds  130  that will allow ablation of calcific plaque. The rotational atherectomy device  108  may include a lumen to allow passage of said guidewire  110 . All the above equipment may be radiopaque to allow visualization under fluoroscopic guidance. 
         [0034]    A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.