Abstract:
A stiffenable balloon catheter assembly capable of being converted from an “over-the-wire” mode with respect to a quidewire extending therethrough to a “rapid-exchange” mode with respect to a guidewire extending therethrough, and vice versa. The catheter has a plurality of lumens, one lumen however, having a side opening with an obstructable galp, the orientation of which, determines the utilization “mode” of the catheter assembly. Stiffening stylets may be adjustably locked into the lumens, depending upon the “mode”, to control the stiffness of the catheter assembly during its utilization within a patient.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This is a continuation of application Ser. No. 07/681,805, filed Apr. 5, 1991. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates to a catheter having a balloon at its distalmost end, and having means for adjustably controlling the stiffness of the catheter shaft, and more particularly to a convertible-type balloon catheter having stiffener means disposed within the catheter.  
         [0004]     2. Prior Art  
         [0005]     Balloon catheters are utilized for insertion into the human body into lumens therewithin. The catheters are of necessity made of a flexible plastic extrusion such as polyethelene, polyester or polyamide. Advancement and manipulation of a catheter requires a certain stiffness or pushability of the catheter itself, by the physician, without injuring the patient in which the catheter is laced.  
         [0006]     A number of approaches have been made, in attempting to provide stiffness to catheters. U.S. Pat. No. 4,964,853 to Sugiyama et al shows a balloon catheter having a braided wire member disposed within the catheter body itself in a mesh-like manner. Mesh is imbedded in the wall of the inner tube. U.S. Pat. No. 4,875,841 to Higgins shows a balloon catheter having a coiled wire arranged within the proximalmost hub, which coiled wire extends in an uncoiled manner within the body of the catheter shaft itself. The coil and the wire itself being co-rotatable so as to provide rotational stiffness to the catheter.  
         [0007]     U.S. Pat. No. 4,822,345 to Danforth shows a variable stiffener balloon catheter, for percutaneous transluminal coronary angioplasty procedures. This patent to Danforth shows a method of providing for variable flexibility, by the use of a longitudinally extended balloon arranged along the exterior of the catheter shaft. Pressurization or depressurization of this balloon is effectuated by a syringe, which pressurizably controls the rigidity of the balloon itself. A further embodiment of this concept of Danforth utilizes relatively stiff wires running through channels in the periphery of the catheter, the wires adding the stiffness to the catheter.  
         [0008]     The preformed catheter assembly shown in U.S. Pat. No. 4,738,667 to Galloway discloses a sheath which is slideably mounted over the catheter so as to be moved from the proximal to the distal end, to straighten out the distal end during insertion and removal of the catheter from a body. The catheter assembly shown in U.S. Pat. No. 4,737,152 to Alchas shows a stylet or stiffening wire arranged within a lumen connected to the closed distal end of the catheter and also there is a loop on its proximalmost end. The loop is arranged in a rotatable knob to facilitate rotation of the distal end of the catheter while providing stiffness, while the proximal end is turned.  
         [0009]     U.S. Pat. No. 4,586,923 issued to Gould et al shows a curving tip catheter having a catheter body which includes a sheath of braided wire having a meshlike configuration positioned around the wall of the tubular body to provide tortional stiffness to the body relative to the flexible tip. In an alternative embodiment, a relatively stiff but bendable inner plastic tubing can be inserted within the tubular body to provide tortional stiffness to that body. In a somewhat similar vein, U.S. Pat. No. 4,516,972 to Sampson shows a guiding catheter having a helically wound ribbon of flexible material embedded within the wall of the catheter, so as to provide tortional rigidity and stiffness.  
         [0010]     In yet a further embellishment on the idea of stiffening a balloon catheter, U.S. Pat. No. 4,448,195 to LeVeen et al shows a reinforced balloon catheter which has a guidewire adapted to be inserted for stretching the catheter when it is inserted into a blood vessel to stiffen the catheter and position it. In an alternative arrangement, a braided shell wire reinforcement is used within the braids, which are placed at the beginning and endings of the thinned portion of the catheter. U.S. Pat. No. 4,033,331 to Guss et al, discloses a contour or stiffening wire slideably disposed within a lumen extending substantially the full length of the catheter. Slight retraction of the stiffening wire from the distal end of the lumen permits catheter to assume a predetermined curvature thereat.  
         [0011]     It is thus an object of the present invention to provide a catheter having variable stiffness capabilities therewithin. The catheter of the present invention should overcome the problems of the prior art by getting the physician to properly adjust the rigidity or stiffness of the catheter shaft according to the particular situation that warrants it in conjunction with the capability of utilizing the catheter shaft in a convertible manner between a “rapid-exchange” mode and an “over-the-wire” mode.  
       BRIEF SUMMARY OF THE INVENTION  
       [0012]     The present invention comprises a balloon catheter having a catheter shaft with at least three lumens extending from the proximal to the distal ends thereof. The first and second lumens may preferably but not necessarily be of cresent shape in cross-section, and the third lumen is of circular cross-section. At least one of the cresent shaped lumens has a stiffening mandrel extending therethrough. In a preferred embodiment, the third lumen has a side opening arranged relatively close yet proximal to the balloon at the distal end of the catheter assembly.  
         [0013]     The balloon on the distal end of the catheter shaft is in fluid communication with one of the cresent shaped lumens. The first shaped lumen has a closed distalmost end, at the proximal end of the balloon.  
         [0014]     The third lumen, preferably of circular cross-section, extends from the proximal end of the catheter shaft, and through the balloon, open at its distalmost end at the distal end of the balloon. The third lumen is adapted to receive a guidewire, either through the entire length thereof, or from an opening proximal of the balloon and through to its distalmost end.  
         [0015]     In a preferred embodiment, a guidewire is adaptable to enter the third “distal” lumen at its opening at the distalmost end of the catheter and extend through that lumen, through the balloon, and exit out the side opening through the sidewall of the catheter, proximal of the balloon. The side “guidewire” opening of the third lumen being disposed through the wall of the catheter shaft at a location which is also proximal to the distal end of the stiffening mandrel in the first cresent shaped lumen. This rapid exchange mode with a guidewire extending partway through may occur with a stiffening stylet disposed within the third lumen, the stylet extending up to a location adjacent the side opening, from the proximal end of the catheter. This same lumen, a portion of which is utilized for the “rapid-exchange” mode, is utilized in its entire length, for the catheter in its “over-the &#39;wire” mode, where a guidewire enters the distal opening of the third “distal” lumen, and exits at the proximal end of the catheter at the proximal end of that third lumen, through a connector or adaptor.  
         [0016]     The present invention thus comprises a multiple lumen catheter (at least three lumens) having proximal and distal ends, the proximal end having a Y-connector thereat for adaptation of inflation devices or control functions, the distal end comprising an inflatable elongated balloon.  
         [0017]     A first of the lumens has an elongated stiffening mandrel disposed therein, the lumen being closed at its distalmost end. The stiffening mandrel being preferably made of Nitinol. A second of the lumens extending from the connector, and into the balloon, providing fluid communication therewith. The third of the lumens being preferably circular in cross-section, extending from the connector and through the balloon, and open through the distal tip of the catheter shaft. A “side” orifice being disposed through the wall of the catheter and into the third lumen, just proximal (about 15 to 35 cm) of the balloon. The stiffening mandrel in the first lumen extending distally of the side orifice in the third lumen to the proximal end of the catheter, so as to allow a smoother transition of catheter stiffness when the assembly is utilized in a rapid exchange mode—that is, when a guidewire extends only part way through the third lumen, out through the “side” orifice after entering that lumen distally and to help transmit “push” on the catheter shaft from its proximal end. The same lumen therefore, in the same catheter, functioning as a lumen for an “over-the-wire” mode, as well as a “rapid-exchange-wire” mode, using part of the lumen for a guidewire and part of that lumen for catheter stiffening assistance. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     The objects and advantages of the present invention will become more apparent when viewed in conjunction with the following drawings, in which:  
         [0019]      FIG. 1  is a sectional side-elevational view of the distal portion of a catheter assembly constructed according to the principles of the present invention;  
         [0020]      FIG. 1   a  is an enlarged view of the “side opening” shown in cross-section in  FIG. 1 ;  
         [0021]      FIG. 2  is a cross-sectional view taken along the lines II-II of  FIG. 1 ;  
         [0022]      FIGS. 3   a ,  3   b , and  3   c  are side-elevational views of stiffening mandrels contemplated with this catheter assembly;  
         [0023]      FIG. 4  is a side-elevational view of a catheter assembly showing a bifucated connector therewith;  
         [0024]      FIG. 5  is a side-elevational view of the proximal end of the catheter assembly showing a trifurcated connector therewith;  
         [0025]      FIG. 6  is a side-elevational view of the catheter assembly in an “over-the-wire” mode;  
         [0026]      FIG. 7  is a side-elevational view of the catheter assembly in a “rapid exchange mode” configuration; and  
         [0027]      FIG. 8  is a side-elevational view of the catheter assembly in a further embodiment thereof.  
         [0028]      FIG. 9  is a side view of a part of a catheter shaft, in a further embodiment of the side opening;  
         [0029]      FIG. 10  is a plan view of the opening shown in  FIG. 9 ;  
         [0030]      FIG. 11  is a side view of part of a catheter shaft in yet a further embodiment or the side opening, and;  
         [0031]      FIG. 12  is a plan view of the opening shown in  FIG. 11 .  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]     Referring to the drawings now in detail, and particularly to  FIG. 1 , there is shown the distal portion of a catheter assembly  10 , also shown in its extendedmost form in  FIG. 4 . The catheter assembly  10  comprises an extruded catheter shaft  12  having a plurality of lumens disposed axially therethrough. The catheter shaft  12  has a first lumen  14 , and a second lumen  16 , both of which are preferably, but not necessarily of cresent shape, as shown in the cross-sectional view of  FIG. 2 . The catheter shaft  12  also includes a third lumen  18 , which is preferably of circular cross-section.  
         [0033]     The catheter shaft  12  has an elongated balloon  20  disposed about its distalmost end, in a known manner. The first lumen  14  extends from an opening, not shown, in a connector  22 , shown in  FIG. 4 , distally towards a closed end  24 , at the proximal end of the balloon  20 . A stiffening mandrel  26 , as shown in  FIG. 1 , is disposed within the length of the first lumen  14 . The stiffening mandrel  26  may have a ball welded tip  28  or be otherwise tapered and flexible on its distalmost end, to prevent puncture of the lumen  14  by the mandrel  26 .  
         [0034]     The second lumen  16  extends from the connector  22 , through the shaft  12 , parallel to the first lumen  14 , except that the second lumen  16  is in fluid communication with the balloon  20 , as shown in phantom lines  17 , in  FIG. 1 . The second lumen  16  provides a conduit for pressurized fluid for inflating and deflating the balloon  20  from an inflation/deflation device, not shown, which would be adaptable to the connector  22 . It is to be noted that the view of  FIG. 1  is sectioned to show the first lumen  14  and the third lumen  18 , and not longitudinally bisect the web of material  19  separating the first and second lumens  14  and  16 .  
         [0035]     The third lumen  18 , of generally circular cross-section, extends from the connector  22 , through the shaft  12 , and through the balloon  20 , opening distally of the balloon  20 , as shown in  FIGS. 1 and 1 A. The third lumen  18  is not in fluid communication with the balloon  20 .  
         [0036]     An opening or side orifice  30  is disposed through the wall of the catheter shaft  12 , and into the third lumen  18 , as shown in  FIG. 1 . The side opening  30  in this preferred embodiment is preferably a slightly oval opening of about 3 mm long and 0.5 mm wide, arranged at a sharp angle “A” of about 20 to about 60 degrees with respect to the longitudinal axis of the shaft. The side opening  30  includes a valve-like cover flap  32 , integral with the shaft  12  with a distally tapering edge  33 , the flap  32  being about the size to cover the opening  30 , and is resilient so as to allow it flex over the opening  30 , and within the third lumen  18 , obstructing it somewhat, depending upon how the flap  32  is being biased. The side opening  30  is disposed a distance “x” of about 15 to about 35 cm. from the proximal end of the inflated balloon  20 , as shown in  FIGS. 1 and 4 . The third or “distal” lumen  18  may thus be utilized in its entire length, from the proximal connector  22  to its distalmost orifice, for receiving a guidewire in an “over-the-wire” mode, the flap  32  roughly covering the inside of the opening  30 . The lumen  18  may also be utilized, from the opening  30  to its distal end, in a “rapid-exchange-wire” mode with a guidewire extending through the distal end of the third lumen  18  and out the opening  39  once the flap  32  is flexed out of the way.  
         [0037]     An RO (radio opaque) marker band  34  is disposed about the catheter shaft  12 , (essentially the structure comprising the third lumen  18 ), at the mid-point of the balloon  20  in either the “over-the-wire” mode or the “rapid-exchange” mode.  
         [0038]     In one embodiment of the present invention, where the catheter assembly  10  is utilized as aforementioned in the traditional “over-the-wire” catheter, a guidewire  50 , normally initially having been inserted into a patient&#39;s vessel, and having its proximal end outside of the patient, has that proximal end inserted through the distal end of the catheter assembly  10 , through the “distal” or third lumen  18 , and it extends proximally, out of the proximal guidewire connector  42 , as shown in  FIG. 6 . The flap  32  performs basically like a valve, by shutting itself against the opening  30 , thus permitting an unobstructed lumen for passage of the guidewire  40 , or for passage of pressurized fluid injected proximally in the lumen  18  to pass through the lumen  18 , to escape primarily out of the distal end of the catheter shaft  12  through the lumen  18 .  
         [0039]     In a further embodiment of the present invention, where the cateter assembly  10  may be utililized in the aforementioned “rapid-exchange” mode, the guidewire  50 , normally initially inserted into a patient&#39;s vessel, and having its proximal end outside of the patient, has that proximal end inserted through the distal end of the catheter assembly  10 , through the “distal” lumen  18 , and extending outwardly proximally, through the side opening  30  as shown in  FIGS. 1 and 7 . The guidewire  50  in this mode, extends parallel to and external of the shaft  12 , proximal of the side opening  30 . The enlarged view in  FIG. 1A  depicts the guidewire  50  shown in phantom lines, and the flap  32  in close fitting overlapping relationship to the guidewire  50 . During the threading of the guidewire through the distal lumen  18 , it is anticipated that the shaft  12  would be bent into a “U” shape at the opening  30 , with the opening  30  in the trough of the “U”, so as to cause the flap  32  to bend “away” from the opening  30 , obstructing the lumen- 18  proximally therepast to permit the quidewire  50  to be threaded through the lumen  18  and out the opening  30 .  
         [0040]     Additionally, when the catheter assembly  10  is utilized in this “rapid-exchange” mode, a stiffening stylet  52  may be inserted within the “distal” or third lumen  18  through the connector  22 , as shown in  FIGS. 1, 1A  and  2 . The stiffening stylet  52  has a distal end  54  which would extend only up to the side opening  30 , and no further. The stiffening stylet  52  may have several different configurations, such as shown in  FIG. 3A, 3B  or  3 C. The stylet  52  shown in  FIG. 3A , is a straight mandrel  54 , having uniform diameter along its entire length. The stylet  52  shown in  FIG. 3B , is a tapered mandrel  56 , having an initial diameter (its non-tapered end) of about 0.20 inches, and tapering about 5 cm. or more along its distal length  57  to a diameter of about 0.008 inches. The stylet  52  shown in  FIG. 3C  is a tapered mandrel  58 , similar to the mandrel  56  shown in  FIG. 3B , but having a ball weld  60  therein, of a diameter of about 0.020 inches. Each stylet  52  may be made from a stainless steel or Nitinol material, in a known manner.  
         [0041]     It is critical to the present invention that the location of the distalmost end of the stiffening mandrel  26  emplaced within the first lumen  14 , as shown in  FIG. 1  be juxtaposed distal to the location of the side hole  30  in the distal lumen  18  of the shaft  12 .  FIG. 5  shows a trifurcated connector  59  mounted on the proximal end of a catheter shaft  12  having a locking hub  61  which would be arranged to adjustably lock at stiffening stylet  26  within the first lumen  14  if desired. A further locking hub  63  may be arranged off of the connector  59  to adjustably seize a stiffening mandrel  52  in the third lumen  18  for longitudinal adjustment thereof, at the physicians option, while the catheter is being utilized in the “rapid-exchange” mode.  
         [0042]      FIG. 8  shows a further adaptation of the catheter assembly  10 , wherein a plurality of orificii  66  is disposed through the wall of the catheter sheath  12  to provide fluid communication with the distal lumen  18  from the outside of the catheter shaft  12  at a location proximal of the balloon  20 , and distal of the side hole  30 . The orificii  66  are about 0.025 inches in diameter, and function as openings for passive perfusion. A further similar plurality of orificii  68  is disposed through the wall of the sheath  12  and distal of the balloon  20 , to provide fluid communication with the distal lumen  18 , to function as openings for passive perfusion with respect to that lumen  18 .  
         [0043]     A further embodiment of the side hole  30  is shown in  FIG. 9 , wherein a portion of a catheter shaft  74  has a “distal” lumen  76  extending therethrough, in a manner similar to the aforementioned catheter shaft  12 . A slit  78  is cut diagonally through the outer wall of the catheter shaft  74 , making a flap  80 , which when flexibly lifted away from the lumen  76  provides a “D” shaped opening, through which a guidewire  82  may be passed.  FIG. 10  shows the flap  80  in its “at rest” configuration, with the “D” shaped opening closed, to provide a full passage lumen  76  thereadjacent.  
         [0044]     A yet another embodiment of the side hole  30  is shown in  FIG. 11 , wherein a portion of a catheter shaft  84  has a “distal” lumen  86  extending therethrough. A slot  88  about 2 cm. long and 0.05 cm wide is diposed longitudinally through the outer wall of the catheter shaft  84 , to make a flexibly openable orifice which a guidewire  90  may be passed.  FIG. 12  shows the slot  38  in a plan view, in its “at rest” configuration.  
         [0045]     Thus what has been shown is a novel stiffened catheter assembly  10  capable of being utilized by a physician as an “over-the-wire” catheter with adjustable stiffness means therewith, or optionally as a “rapid-exchange-wire” catheter apparatus, also including the capability of being able to control or vary the stiffness of the catheter shaft by selective insertion and/or controlled withdrawal of a stiffening stylet adaptably arranged within the guidewire lumen, the “rapid-exchange-wire” mode being facilitated by a side opening having valve-like obstructable flap across its inner side to minimize fluid exchange when that lumen accepts the catheter to be utilized in its full length “over-the-wire” mode. In its use as either a “rapid-exchange-wire” or an “over-the-wire” mode, the portion of the “distal” lumen enclosing the guidewire may have a plurality of orificii through the wall of the catheter shaft just proximal and just distal of the elongated inflated balloon, to permit perfusion of body fluid across the then expanded balloon in the body vessel.