Abstract:
A system and method for making at least one cut in a catheter, guide wire or other elongate cylindrical object having a lengthwise axis, comprising a securing means for repeatedly releasing and then holding the elongate object in a position suitable for cutting it at an angle or transversely relative to its lengthwise axis, a manipulating means for moving the elongate object so that it can be disposed in the position suitable for cutting when it is released by the securing means, and a cutting means for forming the at least one precision cut in the elongate object to any desired depth. The securing means preferably comprises a rotatable collet clamp, and the manipulating means preferably comprises a pinch roller assembly for advancing and holding the elongate object. The cutting means is preferably a mechanical blade mounted on a rotatable spindle, and is free to move vertically and horizontally with respect to the elongate object to thereby control the location, size and depth of the cuts in the cylindrical object disposed adjacent thereto. The clamp is configured to hold and position the object to be cut so as to expose the entire circumference of the cylindrical object to the saw blade if desired. By releasing the clamp, the pinch roller advances the cylindrical object before the clamp is re-engaged to securely hold the cylindrical object for cutting.

Description:
This application is a division of U.S. patent application Ser. No. 08/714,555, filed on Sep. 16, 1996 now U.S. Pat. No. 6,014,919. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention pertains to making precision cuts in catheters and guide wires. Specifically, a device for holding, advancing, rotating and then cutting a catheter or guide wire is provided which is able to manipulate the catheter or guide wire in two degrees of freedom to enable precision control of the location of the cuts. Various clamping mechanisms are provided for manipulating the catheter or guide wire, resulting in controlled variation in mechanical properties. 
     2. State of the Art 
     Making cuts in catheters and guide wires requires precision in order to ensure reliability because of the medical applications in which they are used. However, it is also important to control costs of production so that costs to the health care industry can be minimized. 
     The state of the art is typified by such devices as grinding wires, wound coils, and lasers for making the cuts. But these devices often suffer from high cost or imprecise or difficult control mechanisms for properly positioning both the device to make the cut and the cylindrical object to be cut. 
     What is needed is a method and apparatus for making cuts in catheters and guide wires which allows precise control of characteristics of the cuts. This entails precision holding, advancement and rotation of the generally cylindrical object while at least one saw blade is itself advanced to make the cut and retracted afterward. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a method and apparatus for forming precision cuts in elongate cylindrical objects including catheters and catheter guide wires. 
     It is another object to provide a method and apparatus for forming precision cuts by manipulating a cylindrical object in two degrees of freedom to control the parameters of the cuts. 
     It is yet another object to provide a method and apparatus for holding, advancing and rotating a cylindrical object to be cut. 
     These and other objects are realized in a preferred embodiment of a system for making cuts in a catheter, guide wire or other elongate cylindrical object having a lengthwise axis. The system generally comprises a securing means for repeatedly releasing and then holding the elongate object in a position suitable for cutting it at an angle or transversely relative to its lengthwise axis, a manipulating means for moving the elongate object so that it can be disposed in the position suitable for cutting when it is released by the securing means, and a cutting means for forming the at least one precision cut in the elongate object to any desired depth. The securing means preferably comprises a rotatable collet clamp. The manipulating means preferably comprises a pinch roller assembly for advancing and holding the elongate object. The cutting means is preferably a mechanical blade mounted on a rotatable spindle. The clamp is able to hold the object to be cut, as well as position it by, for example, rotation to thereby expose the entire circumference of the cylindrical object to the saw blade. By releasing the clamp, the pinch roller advances the cylindrical object before the clamp is re-engaged to securely hold the cylindrical object for cutting. 
     The securing means, manipulating means, and cutting means are preferably mounted on a base. The rotating spindle is free to move vertically and horizontally with respect to the base to thereby control the location, length, depth and angle of the cuts in the cylindrical object disposed adjacent thereto. 
     Another aspect of the invention is the ability to make precision cuts by providing means for controlling the rotation and advancement of the object to be cut and movement of the saw blade spindle member. 
     Another aspect is the ability to simultaneously make a plurality of cuts in the object. This is accomplished with a saw blade having a plurality of blades in parallel. Even more cuts can be made by providing more than one saw blade spindle member, where each is independently movable in two degrees of freedom. 
     Another aspect of the invention is to provide more than one spindle member so that blades can simultaneously make precision cuts at different locations along the length of the cylindrical object. 
     These and other objects, features, advantages and alternative aspects of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description taken in combination with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a front elevational view of a preferred embodiment made in accordance with the principles of the present invention. 
     FIG. 1B is a side elevational view of the invention shown in FIG.  1 A. 
     FIG. 2 is an alternative embodiment of a vertically moving member shown reversed in orientation with respect to FIGS. 1A and 1B. 
     FIG. 3 is an alternative embodiment of a horizontally moving member shown reversed in orientation with respect to FIGS. 1A and 1B. 
     FIG. 4A is a front elevational view of an alternative embodiment for the clamping means. 
     FIG. 4B is a side elevational view of the alternative embodiment for the clamping means of FIG.  4 A. 
     FIG. 4C is a front view which shows that the anvil has a slot. 
     FIG. 5 is an alternative saw blade assembly which can be used in all embodiments of the present invention. 
     FIG. 6 is an alternative embodiment which uses two saw blade assemblies to simultaneously make incisions in the catheter. 
     FIG. 7 is a side view of an alternative embodiment which shows a configuration with a base member, a horizontally movable member, and a vertically moveable member. 
     FIG. 8 is another side view of an alternative embodiment which shows a configuration of a base member, and a lever arm which moves the cutting blade in horizontal and vertical directions. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made to the drawings in which the various elements of the present invention will be given numerical designations and in which the invention will be discussed so as to enable one skilled in the art to make and use the invention. 
     The present invention is illustrated in FIGS. 1A and 1B. FIG. 1A is a front view of the preferred embodiment of the invention, and shows the system for forming precision cuts in a catheter, a guide wire, or other cylindrical objects. For purposes of keeping in mind the intended use of the present invention, a catheter will be referred to as the object being cut, although any cylindrical object can be substituted for the catheter. However, reference to the catheter is only for the convenience of writing in terms of a specific cylindrical object, and should not be considered a material limitation of the invention. However, referring to a catheter keeps present in mind the objective of having a very precise cutting device, where precision is paramount in most medical applications. Furthermore, a catheter is only one embodiment of a medical application, but which easily represents the need for precision. 
     The system  6  shown in FIGS. 1A and 1B is comprised of several elements including a base member  10  for supporting the structure. Coupled in sliding engagement with a vertical base member  12  is a vertically movable member  14  which has a first vertical coupling face  16  and a first horizontal coupling face  18 . The vertical coupling face  16  is slidingly engaged with a base member vertical coupling face  20 . 
     The mechanism  22  for enabling the sliding engagement between the vertical coupling face  16  and the base member vertical coupling face  20  can be any appropriate apparatus. The important consideration is that the vertically movable member  14  not be permitted to move horizontally, or the precision of the system will be compromised. Therefore, the tolerances of the mechanism  22  must necessarily be small. A good example of an appropriate mechanism  22  is well known to those skilled in the art as a crossed roller bearing slide. 
     The shape of the vertically movable member  14  is shown here as a small backwards “L”. An alternative shape for the vertically movable member  14  is shown in FIG.  2 . The member  14  is flipped over as compared to the embodiment of FIG.  1 A. The important feature of the member  14  is that it provide two faces  16 ,  18  which can be slidably engaged to move vertically and provide a second face on which another member can slidably engage to move horizontally. 
     The system in FIGS. 1A and 1B is also comprised of a horizontally movable member  24  which has a spindle end  26  and a second horizontal coupling face  28 . This horizontally movable member  24  is slidably engaged at its second horizontal coupling face  28  to the vertically movable member  14  at its first horizontal coupling face  18 . It should be observed that the vertically movable member  14  and the horizontally movable member  24  are capable of moving independently of each other. In this way, the system achieves two independent degrees of freedom of movement. 
     The spindle end  26  of the horizontally movable member  24  provides a horizontal slot  30  in which a spindle  32  is disposed. 
     The slot  30  is generally circular to serve as a receptor for the round shaft  34  of the spindle  32 . The spindle shaft  34  has disposed on a working end  36  thereof at least one circular saw blade  38 . The circular saw blade  38  is disposed vertically on the spindle shaft  34 , but may also be angled in other embodiments. 
     The spindle shaft  34  is coupled to a drive motor by gears, belts, direct drive, or any other appropriate means (not shown) which will cause the spindle shaft  34  to rapidly rotate. The drive motor (not shown) can be disposed in any appropriate location relative to the spindle shaft. In a preferred embodiment, the spindle shaft  34  is driven by a brushless DC motor through a toothed timing belt. 
     The circular saw blade  38  is typical of those found in the art. In a preferred embodiment, the cutting edge  40  of the saw blade  38  is coated with industrial diamonds. 
     The means for holding and otherwise manipulating a catheter  8  to be cut is the clamping member  50 . The clamping member  50  is comprised of two major assemblies: the clamp  52  and the clamp feeding (supplying) means  54 , or the device which feeds the catheter  8  to and then through the clamp  52 . The clamping member  50  is also coupled to the base member  10  and disposed to hold the clamp  52  in a position for easy feeding of the catheter  8  to the circular saw blade  38 . 
     In the preferred embodiment, the clamp  52  is of the type known to those skilled in the art as a collet clamp. A collet clamp is a slotted cylindrical clamp inserted tightly into the tapered interior of a sleeve or chuck on a lathe to hold a cylindrical piece of work. In FIG. 1A, the cylindrical shape of the clamp  52  is visible. It is slotted in that the clamping arms  58  are separate from each other so that they can pull away from the catheter  8  when disengaging, and then securely come together around the catheter  8  when engaging. 
     In a preferred embodiment, a desirable feature of the clamp  52  is that it is rotatably mounted within the clamping member  50 . The collet clamp  52  can then rotate so as to dispose a different portion of the surface of the catheter  8  to the saw blades  38 . The mechanism for rotating the clamp  52  is shown generally at  56 , and is comprised of the clamp  52  which is held in a frame which can rotate with respect to the saw blade  38 . 
     The clamp feeding (supplying) means  54  seen in FIG. 1B is shown in this preferred embodiment to be comprised of a pinch roller assembly  60 ,  62  working in conjunction with a feed roller  66 . As FIG. 1B should make clear, the pinch roller assembly  60 ,  62  feeds the catheter  8  to the clamp  52  by using friction created between two opposing members  60 ,  66 . The upper member is the pinch roller  60 . The lower member is the feed roller  66 . The feed roller  66  has an axle  68  mounted in the clamp feeding means  54  so that the feed roller  66  can roll. The pinch roller  60  is disposed at the end of a lever arm  62  which pivots at a pivoting end  70 . Located distally from the pinch roller assembly along the length of the lever arm is a hole  72 . One end of a spring  64  is inserted therethrough, and the other end of the spring  64  is coupled at another hole  74  to the clamp feeding means  54 . The spring  64  provides the tension necessary for the feed roller  64  to push the catheter  8  to the clamp  52 . 
     Having described most of the components in a preferred embodiment of the catheter cutting assembly  6 , the operation of the assembly  6  is as follows. First, the uncut catheter  8  is placed between the pinch roller  60  and the feed roller  66 . This can be done by raising the lever arm  62  by stretching the spring  64 . Releasing the lever arm  62  causes the pinch roller  60  to push down against the feed roller  66 , with the catheter  8  disposed therebetween. A drive mechanism (not shown) is coupled to the feed roller  66  to cause it to roll and thereby push the catheter  8  toward the clamp  52 . The clamp  52  should be in a disengaged position (hole through clamp is larger than diameter of the catheter  8 ) so that the catheter  8  can be fed easily therethrough. After passing through the clamp  52 , the catheter  8  is fed sufficiently far past the circular saw blade  38  so that it is in a proper position to have an incision made in or through its surface. 
     When the catheter  8  is positioned correctly, the clamp  52  is engaged and the saw blade  38  is advanced to make cutting contact. Before cutting, the saw blade  38  will always be positioned in a retracted position. The retracted position is both vertically below and horizontally pulled away from the catheter  8 . The first movement of the saw blade  38  is  1 ) horizontal advancement toward the catheter  8 . This is accomplished by moving the horizontally movable member  24  relative to the vertically movable member  14  to which it is attached. The horizontally movable member  24  is moved until it has reached the depth of the incision to be made in the catheter  8 . The next step  2 ) comprises the vertically movable member  14  moving upwards relative to the base  10  to which is coupled to thereby make the cut. The saw blade  38  is then immediately retracted by moving the vertically movable member  14  away from the catheter  8 . The horizontal member is moved only when the next cut is at a different depth or when all cutting is complete. 
     If another cut is to be made, the collet clamp  52  is released as step  4 ). The catheter  8  is then fed through the clamp  52  by the feed roller  66  as step  5 ). The collet clamp  52  is then re-engaged in step  6 ) and, if necessary, the collet clamp  52  is rotated to expose a different position of the catheter  8  to the saw blade  38 . The saw blade  38  is then moved horizontally if the depth of cut is to change, and then vertically to make the cut and steps  1 ) through  7 ) repeat as often as necessary until all the incisions have been made or the catheter  8  is no longer capable of being grasped by the feed roller  66  and opposing pinch roller  60 . 
     The above description of the operation of the catheter cutting system  6  describes the different roles served by the clamp  52 . When the circular saw blade  38  is making a cut in the catheter  8 , the clamp  52  holds the catheter  8  steady. When the cut has been made in the catheter  8 , the catheter  8  is fed through the clamp  52  by causing the clamp to disengage from around the catheter  8 . After being disengaged, the catheter  8  is fed through the clamp  52  until the next incision point on the catheter  8  is in position relative to the saw blade  38 . The clamp  52  re-engages so as to be disposed snugly around the catheter  8  to again prevent movement of the catheter  8  during cutting. 
     It should be recognized from the description above that the width of a cut into the catheter  8  is limited to the width of the circular saw blade  38 . A wider cut therefore requires that the catheter  8  be advanced slightly past the saw blade  38 . However, advancement does not take place while making a cut. The saw blade  38  must be withdrawn so that the clamp  52  can disengage from around the catheter  8  while it is advanced. This is necessary because allowing cutting of the catheter  8  when the clamp is disengaged would create an imprecise or useless cut. 
     Variations of the preferred embodiment are illustrated in FIGS. 4A and 4B which show that the clamping means  52  has been modified. As can be seen in FIG. 4A, a stationary support surface  110  is provided with a slot  112  therein for supporting the catheter  8  from below. The slot  112  guides and holds the catheter  8  before, during and after cutting. Holding the catheter  8  not only allows more precise cutting, but prevents damage to the catheter  8  which might otherwise occur. A movable clamping member  114  or anvil is also provided to thereby apply force to the catheter  8  which is clamped between the anvil  114  and the slotted support surface  110 . FIG. 4B also shows that the anvil  114  has a mechanism  116  which allows the anvil  114  to move vertically with respect to the support surface  110 . In FIG. 4B the vertical movement mechanism  116  is shown as bearings. 
     FIG. 4C is provided to illustrate an alternative embodiment of the anvil  114 . As shown, the anvil  114  has a slot  158  which will hold the catheter  8  more securely for cutting. 
     FIG. 5 illustrates a modification to the spindle  32  and saw blade  38  arrangement shown in FIGS. 1A and 1B. Specifically, a plurality of saw blades  38  are shown as being mounted in parallel on the same spindle  32 . This also means that the saw blades  38  are necessarily coaxial. It is also preferred that the saw blades  38  have the same diameter so that no individual saw blade  38  makes a deeper incision in the catheter  8  than any of the others. However, it should be apparent that if the spindle  32  or the saw blades  38  are easily detachable from the system  6 , then saw blades of varying diameters might be mounted on the same spindle  32  to achieve a consistent pattern of cuts having different depths. 
     FIG. 6 is an illustration of another alternative embodiment of the present invention. The vertically movable member  14  is shown having another shape which enables it to have disposed thereon two horizontally movable members  24 , each having its own associated saw blade or blades  38 . This embodiment enables the catheter  8  to be simultaneously cut at different circumferentially defined points on the catheter surface. This is especially useful in making multiple cuts in catheters, for example, on diametrically opposed positions on the catheter  8 . 
     It should be noted that while the preferred embodiment has been defined as having a horizontally movable member with the spindle for the saw blade coupled thereto, the placement of the vertically and horizontally movable members can be switched as shown in FIG.  7 . In this arrangement, the horizontally movable member  144  is coupled to the base member  142  and the vertically movable member  146 , and the vertically movable member  146  has a spindle  148  rotatably coupled thereto. 
     In another alternative embodiment of the present invention, shown in FIG. 8, a lever arm  150  is pivotally connected to the base member  154 , and is capable of movement in at least two degrees of freedom so that it can move vertically and horizontally to position a spindle end  152 . 
     Another aspect of the invention which should be clarified is that rotating the catheter is not limited to using a rotatable clamping mechanism. For example, the clamp can be non-rotatable and disengaged to enable the catheter feeding mechanism to rotate the catheter, and then re-engage the clamp to make additional incisions. Furthermore, the clamp and the catheter feeding mechanism can be rotated together before additional incisions are made. 
     Alternative aspects of the invention include the substitution of a non-mechanical cutting instrument for the rotating blade of the presently preferred embodiment. For example, a laser can be provided for cutting through materials which are mounted on the system. 
     It should also be realized that rotating blades are not the only type of mechanical blade which can be utilized. Conventional “sawing” blades can also be provided. 
     It is to be understood that the above-described embodiments are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention. The appended claims are intended to cover such modifications and arrangements.