Abstract:
A system for performing a medical treatment in a blood vessel while providing downstream microcirculatory system protection, the system being composed of: a catheter having a longitudinal axis, a distal end, an outer lateral surface, a central blood bypass flow lumen extending along the longitudinal axis and opening at the distal end, blood flow inlet and outlet openings extending from the lateral surface and communicating with the bypass flow lumen, and first and second inflation lumens extending to the lateral surface at respective first and second locations that are spaced apart along the longitudinal axis and that are between the inlet openings and the outlet openings; and first and second inflatable members secured to the lateral surface and each having an interior that communicates with a respective one of the first and second inflation lumens, wherein the catheter has a thin outer wall enclosing a hollow interior that is completely occupied by the bypass flow lumen, except for the space occupied by the first and second inflation lumens.

Description:
[0001]    This is a continuation-in-part of U.S. application Ser. No. 10/005,699, filed on Dec. 7, 2001 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to the treatment of obstructions in body passages, and particularly in arteries.  
           [0003]    Treatments of this type typically produce debris that, if allowed to enter the microcirculatory system downstream of the treatment site, can cause damage to organs and tissues.  
         BRIEF SUMMARY OF THE INVENTION  
         [0004]    The invention provides a novel system that allows an angioplasty treatment, possibly with stenting or primary stenting, to be performed, while preventing the entry of debris resulting from such treatment into the distal microcirculatory system of a patient and assuring a continued supply of blood flow downstream of the obstruction during the angioplasty treatment and protection of organs and tissue downstream of the treatment site against damage that might be caused by debris resulting from the treatment.  
           [0005]    The system according to the invention, for performing a medical treatment in blood vessels, is basically composed of: a catheter having a longitudinal axis, a distal end, an outer lateral surface, a central blood bypass flow lumen extending along the longitudinal axis and opening at the distal end, blood flow inlet and outlet openings extending from the lateral surface and communicating with the bypass flow lumen, and first and second inflation lumens extending to the lateral surface at respective first and second locations that are spaced apart along the longitudinal axis and that are between the inlet openings and the outlet openings; and first and second inflatable members secured to the lateral surface and each having an interior that communicates with a respective one of the first and second inflation lumens, wherein the catheter has a thin outer wall enclosing a hollow interior that is completely occupied by the bypass flow lumen, except for the space occupied by the first and second inflation lumens.  
           [0006]    The annular bypass lumen is formed adjacent the outer wall of the catheter. Therefore, the blood inlet and outlet openings in communication with the bypass flow lumen can be formed in a simple manner. In addition, these openings can be made relative large to assure an adequate blood flow, a flow of at least 30 cc/min being considered necessary to maintain tissue viability. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0007]    [0007]FIG. 1 is a side elevational view, partly in cross section, of one preferred embodiment of a catheter system according to the invention.  
         [0008]    [0008]FIGS. 2 and 3 are cross-sectional views taken along lines  2 - 2  and  3 - 3 , respectively, of FIG. 1.  
         [0009]    [0009]FIG. 4 is a view similar to that of FIG. 1 showing a second embodiment of the invention.  
         [0010]    [0010]FIGS. 5, 6 and  7  are cross-sectional views taken along lines  5 - 5 ,  6 - 6  and  7 - 7 , respectively, of FIG. 1.  
         [0011]    [0011]FIG. 5′ is a view similar to, and in the same plane as, FIG. 5, showing a modified form of construction of the second embodiment.  
         [0012]    [0012]FIG. 8 is a side elevational view of a third embodiment of a catheter system according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    The following detailed description will be provided with reference to all three Figures.  
         [0014]    The system according to the invention is composed essentially of a dilatation and embolic blocking catheter  12  and a surrounding, movable suction catheter  14 , which may be in the form of a hypo tube.  
         [0015]    Catheter  12  is provided with a central guidewire lumen  20  that is preferably coaxial with the longitudinal axis of catheter  12 , a blood bypass flow lumen  22  that surrounds lumen  20  and is separated therefrom by a cylindrical wall  24 , a proximal inflation lumen  26  and a distal inflation  28 .  
         [0016]    Lumen  20  extends the full length of catheter  12  and in open at the distal end thereof, which is the right-hand end in FIG. 1. Lumen  20  is provided to receive a guidewire  32  that serves to guide catheter  12  to a desired treatment site.  
         [0017]    Catheter  12  is provided with a plurality of blood flow inlet openings  36  and a plurality of blood flow outlet openings  38 , each set of openings  36 ,  38  being distributed circumferentially around the outer lateral wall of catheter  12 . Openings  36  and  38  extend through the lateral wall of catheter  12  into communication with lumen  22 . Lumen  22  does not extend through the full length of catheter  12 . The proximal end of lumen  22  extends to a point upstream of openings  36 , while the distal end of lumen  22  extends downstream of openings  38 . According to the present invention, all openings  36 ,  38  communicating with lumen  22  extend through the lateral wall of catheter  12 .  
         [0018]    Catheter  12  is completed by two inflatable members  40  and  42  carried on the outer wall of catheter  12  and each communicating with a respective one of inflation lumens  26  and  28 . According to preferred embodiments of the invention, member  40  is a low compliance angioplasty balloon, or sleeve, or sheath, and member  42  is a high compliance blocking balloon. Balloons  40  and  42  are located between openings  36 ,  38 . It is particularly important that the blood flow path defined by lumen  22  extend across balloon  42  because that balloon remains inflated for a longer period of time, of the order of several minutes, than does balloon  40 , of the order of a few seconds. In further accordance with the invention, balloon  40  carries a stent  46  that is to be expanded and deployed against the inner wall of a body passage to be treated.  
         [0019]    Catheter  12  can also be provided with circular radiopaque bands adjacent to the proximal and distal edges of both balloons to assist in proper positioning of the catheter.  
         [0020]    In practical embodiments of the invention, catheter  12  can have a size of 2-3 Fr (Fr is a notation indicating outside diameter; n Fr=n/3 mm), with a tapered tip, as shown, that helps to allow the catheter to traverse large obstructions.  
         [0021]    The above-described device is manipulated to perform an angioplasty treatment in the following manner. Firstly, guidewire  32  is introduced into the blood vessel past the site where a treatment is to be performed. This can be achieved by any conventional procedure that allows guidewire  32  to be advanced through the vessel in the direction of blood flow, i.e. so that the distal end of guidewire  32  points downstream. After the guidewire has been advanced to a point beyond the location of the obstruction to be treated, for example with the aid of radiographic fluoroscopic monitoring, catheter  12  is placed over the guidewire so that the guidewire extends through lumen  20 . Catheter  12  is then advanced over the guidewire to the site where the treatment is to be performed, specifically by bringing balloon  40  and stent  46 , if provided, to a location opposite the obstruction. Then, tube  14  is inserted in the blood vessel around catheter  12  and brought to a location substantially as shown in FIG. 1, upstream of the treatment site.  
         [0022]    Then, balloon  42  is expanded by supplying a fluid at a suitable pressure, usually less than 1 atm, via lumen  28  to block the flow of blood between the outer wall of catheter  12  and the blood vessel wall. After balloon  42  has been thus inflated, blood continues to be supplied to the portion of the blood vessel downstream of catheter  12  by flowing through openings  36 , lumen  22  and openings  38 .  
         [0023]    After balloon  42  has been inflated, balloon  40  is inflated by supplying a fluid at a suitable pressure via lumen  26  to press the obstruction outwardly and to expand and deploy stent  46 . This operation generally results in the creation of debris consisting of material that has broken off from the obstruction. This debris will be prevented from flowing downstream of catheter  12  by inflated balloon  42  and will be trapped against the upstream side of balloon  42 .  
         [0024]    As soon as balloon  40  has been deflated, tube  14  is advanced in the downstream direction toward balloon  42  while suction is applied from an external suction source through tube  14 . During this suctioning step, tube  14  can be moved back and forth along the axis of catheter  12  to aid the removal of debris. As a result, debris that has been trapped upstream of balloon  42  will be drawn into tube  14  and removed from the patient&#39;s body, where it can be inspected, possibly with the aid of a microscope. After suction has been performed for a sufficient time to assure removal of all debris, or at least all potentially dangerous debris, balloon  42  is deflated and tube  14  and catheter  12  are removed from the blood vessel.  
         [0025]    A second embodiment of the a system according to the invention is shown in FIGS.  4 - 7  and is composed essentially of a dilatation and embolic blocking catheter  112  and a surrounding, movable suction catheter  114 , which may be in the form of a hypo tube.  
         [0026]    According to this embodiment, catheter  112  is a thin-walled body that is hollow, except for balloon inflation lumens, to be described below, to provide a blood bypass flow lumen  122  having a maximum cross section. Catheter  112  is provided with a proximal balloon inflation lumen  126  and a distal balloon inflation  128 . Lumens  126  and  128  are the only structures within catheter  112  and thus the only structures that reduce the cross section of lumen  122 . Lumen  122  can, but need not, extend the full length of catheter  112  and has a small diameter opening at the distal end thereof for passage of a guidewire  132  that serves to guide catheter  112  to a desired treatment site. Preferably, the opening is made only slightly larger in diameter than guidewire  132  to allow more accurate guidance of catheter  112 . If lumen  122  does not extend through the full length of catheter  112 , the proximal end of lumen  22  may be located at a point upstream of openings  136 , while the distal end of lumen  22  may be located downstream of openings  38 , in the same manner as lumen  22  of FIGS.  1 - 3 , while a guidewire lumen will be provided both proximally and distally of lumen  122 .  
         [0027]    Catheter  112  is provided with a plurality of blood flow inlet openings  136  and a plurality of blood flow outlet openings  138 , each set of openings  136 ,  138  being distributed circumferentially around the outer lateral wall of catheter  112 . All openings  136  and  138  extend through the lateral wall of catheter  112  into communication with lumen  122 . A balloon or stent deployment sleeve or sheath  140  and a balloon  142  are carried on the outer surface of catheter  112  at locations between openings  136  and  138 . It is particularly important that the blood flow path defined by lumen  122  extend across balloon  142  because that balloon remains inflated for a longer period of time, of the order of several minutes, than does balloon  140 , of the order of a few seconds.  
         [0028]    Balloon or sleeve  140  communicates via openings in the wall of catheter  112  with inflation lumen  126  and balloon  142  communicates via other openings in the wall of catheter  112  with inflation lumen  128 . According to preferred embodiments of the invention, balloon  140  is a low compliance angioplasty balloon, sheath, or sleeve, and balloon  142  is a high compliance blocking balloon. In further accordance with the invention, balloon  140  carries a stent  146  that is to be expanded and deployed against the inner wall of a body passage to be treated.  
         [0029]    Catheter  112  can also be provided with circular radiopaque bands adjacent to the proximal and distal edges of both balloons to assist in proper positioning of the catheter.  
         [0030]    In practical embodiments of the invention, catheter  112  can have the following dimensions, identified in FIG. 7:  
         [0031]    (a)—an outer diameter of 1.0 mm (3 Fr.);  
         [0032]    (b)—a wall thickness of 0.127 mm.  
         [0033]    However, the diameter of the catheter can have other values, for example between about 2 Fr and 5 Fr. According to another feature of the invention, dimension b can vary along the length of the catheter and can, for example have a greater value in a region aligned with balloon  140  than in a region between balloon  140  and the distal end of the catheter. A greater thickness in the region aligned with balloon  140  will help to keep the catheter from being compresses radially by the forces generated by balloon  140  during artery wall dilation, while a lesser thickness in the region between balloon  140  and the distal end of the catheter will give lumen  122  a larger cross section.  
         [0034]    The provision of a tapered distal end, as shown, helps to allow the catheter to traverse large obstructions.  
         [0035]    A modified version of the second embodiment is shown in FIG. 5′. This version differs from the embodiment of FIGS.  5 - 7  only in that one inflation lumen, such as, for example, lumen  128  of FIGS.  4 - 7 , is replaced by a lumen  128 ′ that extends outwardly from the outer lateral wall of catheter  112 . This serves to enlarge the flow path provided by lumen  122 .  
         [0036]    A third embodiment of the invention is illustrated in FIG. 8. This embodiment differs from those previously described in two basic respects: balloons  140  and  142  are mounted directly adjacent to one another; and the outer diameter of catheter  212  changes along the length of the catheter, having a larger value, d 1 , at least in the region aligned with balloon  140  and a smaller diameter, d 2 , over all or a part of its length between balloon  140  and the distal end of the catheter. This configuration will act as a sump that increase blood flow through lumen  122 . In addition, as described above with respect the embodiment of FIGS.  4 - 7 , the wall thickness of catheter  212  in the region between balloon  140  and the distal end can be smaller than in the region aligned with balloon  140 . In practical embodiments of the catheter of FIG. 8, d 1  can have a value between 3 and 5 Fr and d 2  can have a value between 2 and 4 Fr, with d 1  always being greater than d 2 .  
         [0037]    By placing balloon  142  directly adjacent balloon  140 , it becomes possible to better prevent the escape of debris at locations that are directly adjacent to a side branch of the artery being treated. Balloon  140  and  142  can be mounted so that their facing edges abut one another.  
         [0038]    According to other possibilities, the catheter system can be constructed so that balloons  140  and  142  are movable longitudinally relatively to one another, for example as disclosed in issued U.S. Pat. No. 5,342,306. According to another possibility, balloon  142  can be spaced from balloon  140  and can be constructed in a manner to expand parallel to the axis of the catheter in a direction toward balloon  140 , as disclosed in U.S. Pat. No. 5,380,284. The contents of these patents are incorporated herein by reference. Both of these alternatives allow the practitioner to better deal with situations in which the region on which an angioplasty treatment is to be performed is located directly adjacent a side branch of the artery being treated.  
         [0039]    Embodiments of the invention can possess one or both of the features described above with reference to FIG. 8  
         [0040]    The above-described device is manipulated to perform an angioplasty treatment in the same manner as described earlier herein with respect to the embodiment shown in FIGS.  1 - 3 .  
         [0041]    The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without undue experimentation and without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. The means, materials, and steps for carrying out various disclosed functions may take a variety of alternative forms without departing from the invention.  
         [0042]    Thus the expressions “means to . . . ” and “means for . . . ”, or any method step language, as may be found in the specification above and/or in the claims below, followed by a functional statement, are intended to define and cover whatever structural, physical, chemical or electrical element or structure, or whatever method step, which may now or in the future exist which carries out the recited function, whether or not precisely equivalent to the embodiment or embodiments disclosed in the specification above, i.e., other means or steps for carrying out the same functions can be used; and it is intended that such expressions be given their broadest interpretation.