Abstract:
An atherectomy device may include a handle having a rotational drive mechanism therein, a drive shaft operably coupled to the drive mechanism and having an abrasive element arranged at a distal end thereof, the drive shaft comprising a first portion and a second portion, wherein the first portion comprises a spin-to-close profile and the second portion comprises a spin-to-open profile.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority to U.S. Provisional Application No.: 61/840,729 entitled Rotating Drive Shaft with Two or More Winding Directions, filed on Jun. 28, 2013, the content of which is hereby incorporated by reference herein in its entirety. The present application is also related to U.S. Provisional Application No.: 61/613,158 entitled Drive Shaft with Improved Collapse and Column Strength, filed on Mar. 20, 2012, the content of which is hereby incorporated by reference herein in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present application relates to devices and methods for removing tissue from body passageways, such as removal of atherosclerotic plaque from arteries, utilizing a high-speed rotational atherectomy device. More particularly, the present application relates to spindles, drive shafts, snakes, or other elongate torsion transferring elements that may be used in an atherectomy procedure. Still more particularly, the present application relates to spin-top-open and/or spin-to-close drive shafts of atherectomy devices. 
       BACKGROUND 
       [0003]    Generally, single-wound drive shafts used in Orbital Atherectomy Devices (OAD) may open or expand when loaded depending on the winding direction relative to the rotational direction of the drive shaft during operation. Such spin-to-open shafts expand under load, with the filer spacing being increased. Alternatively, or in addition, if spacing is not increased under load, the shaft length is reduced. In either case, the outer diameter of the drive shaft increases. 
         [0004]    When the load is reduced or the shaft ceases rotating, the shaft may spring back to its static state. This spring-back action can catch or tear biological material, resulting in unintentional vessel damage and trauma. In addition, the spring-back action can dampen the force actually transmitted and applied to the abrasive element or crown attached to the drive shaft at a distal end. 
         [0005]    In contrast, spin-to-close drive shafts may have a similar but opposite effect to that discussed above with the spin-to-open shafts. Spin-to-close shafts may wrap tighter when loaded or during rotation. In addition, the drive shaft length may be extended beyond its static length and the outer diameter may be reduced. If such a shaft is sufficiently loaded, its outer diameter may be reduced to the point that it locks onto the guide wire. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The present application, in some embodiments, relates to an atherectomy device including a handle having a rotational drive mechanism therein and a drive shaft operably coupled to the drive mechanism and having an abrasive element arranged at a distal end thereof. The drive shaft may include a first portion and a second portion and the first portion may include a spin-to-close profile and the second portion may include a spin-to-open profile. In some embodiments, the drive shaft further comprises a third portion arranged between the first and second portion. The first portion may include a proximal portion of the drive shaft and the second portion may include a distal portion of the drive shaft. In some embodiments, the third portion may include a spin-to-open profile. In additional embodiments, the device may also include a sheath having a lumen extending therethrough and a portion of the drive shaft may be arranged within the lumen. In some embodiments, the lumen may include a diameter defined by an inner wall of the sheath and the spin-to-open profile of the third portion may be configured to contact the inner wall when operating the drive shaft. 
         [0007]    The figures and the detailed description which follow more particularly exemplify these and other embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, which are as follows. 
           [0009]      FIG. 1  is a perspective view of an atherectomy device, according to some embodiments. 
           [0010]      FIG. 2  is a close-up and partial cutaway view of a portion of the distal end of the atherectomy device of  FIG. 1  showing the drive shaft portion of the device arranged within the catheter or sheath. 
           [0011]      FIG. 3  shows a drive shaft having a spin-to-close profile for a clockwise driven drive shaft, according to some embodiments. 
           [0012]      FIG. 4  shows a drive shaft having a spin-to-open profile for a clockwise driven drive shaft, according to some embodiments. 
           [0013]      FIG. 5  shows a combined, spin-to-open/spin-to-close drive shaft, according to some embodiments. 
           [0014]      FIG. 6  shows a coupling element for coupling a spin-to-open and a spin-to-close drive shaft, according to some embodiments. 
           [0015]      FIG. 7  shows a combined, spin-to-open/spin-to-close drive shaft, according to some embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    While the invention is amenable to various modifications and alternative forms, specifics thereof are shown by way of example in the drawings and described in detail herein. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. 
         [0017]      FIG. 1  illustrates one embodiment of a rotational atherectomy device. As shown, the device may include a handle portion  10 , an elongated, flexible drive shaft  20  having a head  27  in the form of a burr, crown, or bit, and an elongated catheter or sheath  13  extending distally from the handle portion  10 . The drive shaft  20  may be constructed from helically coiled wire and the head  27  may be attached thereto. As shown in  FIG. 1  and close-up view in  FIG. 2 , the catheter or sheath  13  may include a lumen in which most of the length of the drive shaft  20  is disposed, except for the head  27  and, in some cases, a short section distal to the head  27 . The drive shaft  20  also may contain an inner lumen, permitting the drive shaft  20  to be advanced and rotated over a guide wire  15 . A fluid supply line  17  may be provided for introducing a cooling and lubricating solution (typically saline or another biocompatible fluid) into the catheter  13 . 
         [0018]    The handle  10  may include a turbine (or similar rotational drive mechanism) for rotating the drive shaft  20  at high speeds. The handle  10  typically may be connected to a power source, such as compressed air delivered through a tube  16  or electrical power delivered with an electrical connection. A pair of fiber optic cables  25 , or a single fiber optic cable, for example, may also be provided for monitoring the speed of rotation of the turbine and drive shaft  20 . The handle  10  also may include a control knob  11  for advancing and retracting the turbine and drive shaft  20  with respect to the catheter  13  and the body of the handle. 
         [0019]    As will be appreciated, when the rotational drive mechanism in the handle  10  is actuated and the drive shaft is spun or otherwise rotated, the drive shaft  20  may experience resistance to rotation at the distal end of the drive shaft  20  and/or along its length. The torsional force within the drive shaft  20  may be lesser or greater depending on the amount of resistance experienced by the drive shaft  20  and the amount of rotational force imparted by the drive mechanism. In some cases, if the distal end encounters an obstruction and comes to an abrupt stop or experiences a quick acting resistance, the torsion in the shaft  20  may be affected by the rotational momentum of the drive shaft  20  and/or drive mechanism as well. 
         [0020]    It is to be appreciated that the direction that a drive shaft  20  is wound, compared to the direction it is driven, affects its response to being driven and, in particular, its response to startup and its response to encountering an obstruction. That is, a drive shaft  20  may include a coiled wire that may be formed by winding on a mandrel, or otherwise formed. As shown in  FIGS. 3 and 4 , the drive shaft  20  may be wound in one of two directions about a longitudinal axis as the coil extends along the axis in a direction A. As shown in  FIG. 3 , the wire  24  may be wound or coiled counterclockwise about the axis  22 . In contrast, as shown in  FIG. 4 , the wire  24  may be wound or coiled clockwise about the axis  22 . Depending on the direction that the resulting drive shafts  20  are driven, the coiled wires may define a spin-to-open drive shaft  20 A or a spin-to-close drive shaft  20 B. For purposes of discussion and simplicity, the present discussion generally assumes that the driven direction is a clockwise drive direction when viewing a device from a proximal, or driving or handle, end of the device. For purposes of  FIGS. 3 and 4 , the drive end is at the left of the figure and resistance may be present along the coil and at the right side of the figure. As such, referring again to  FIG. 3 , this type of drive shaft  20  may be termed a spin-to-close drive shaft. This is because as the drive shaft  20 B spins in the clockwise direction, resistance to such spinning has a tendency to cause the coil to get tighter or close. In contrast, as shown in  FIG. 4 , this type of drive shaft  20  may be termed a spin-to-open drive shaft  20 A. This is because as the drive shaft  20 A spins in the clockwise direction, resistance to such spinning has a tendency to cause the coil to get looser or open. 
         [0021]    As shown near the distal end of each example in  FIGS. 3 and 4 , a portion is shown in cross-section showing that the windings or filers have a pitch defined by how much the windings or filers lay over relative to a line perpendicular to the longitudinal axis  22 . For purposes of discussion going forward, schematic drawing lines that cross the longitudinal axis that are tipped rearwardly or, close to perpendicular, as in  FIG. 3 , will be understood to reflect a spin-to-close drive shaft  20 B and lines that cross the longitudinal axis that are tipped forwardly as in  FIG. 4 , will be understood to reflect a spin-to-open drive shaft  20 A. However, it is to be appreciated that these definitions are with respect to a clockwise drive direction and it is understood that reversing the drive direction may change a spin-to-open drive shaft  20 A to a spin-to-close drive shaft  20 B and vice versa. 
         [0022]    Referring now to  FIG. 5 , and contemplating the difficulties and issues associated with spin-to-open  20 A and spin-to-close  20 B drive shafts, a drive shaft  20  with a combination of spin-to-open  20 A and spin-to-close  20 B elements is shown. As mentioned previously, an atherectomy device may include a handle portion  10  having an air-pressure driven turbine, an electric motor, or another type of drive mechanism for rotationally driving the drive shaft  20 . The drive shaft  20  may extend distally from the handle  10  to a distal end where a crown  27  may be positioned. The crown  27  may be usable to clear arterial blockages and the like. In the present embodiment, the drive shaft  20  may include a proximal portion  26  having a spin-to-open profile  20 A and a distal portion  28  having a spin-to-close profile  20 B. The proximal portion  26  and some of the distal portion  28  may be slidable and rotatable within a catheter or sheath  30  and the proximal portion  26  and distal portion  28  may be secured to one another with a coupling element  32 . 
         [0023]    When the present drive shaft  20  is loaded, the proximal spin-to-open section  20 A may open within the sheath  30  and the relationship of the drive shaft  20  being within the sheath  30  may be advantageous for at least two reasons. First, the sheath  30  may protect against the outwardly expanding filers encountering biological material (i.e., arterial wall) that may be captured when the expanded filers relax, further limiting trauma potential. Secondly, the sheath  30  may limit the shaft diameter expansion at the proximal spin-to-open section  20 A allowing the size of the drive shaft  20  to be controlled. 
         [0024]    In contrast, the distal spin-to-close portion  20 B, when loaded, may close or shrink in diameter. However, the rigidity of the spin-to-close portion  20 B relative to the spin-to-open portion  20 A may be slightly higher such that the spin-to-close portion  20 B may maintain its static diameter and refrain from locking onto the guide wire  15 . As such, the drive shaft  20  may maintain its maneuverability both longitudinally and rotationally relative to the guide wire  15 . 
         [0025]    The combination of a spin-to-open  20 A and spin-to-close  20 B drive shaft may reduce or eliminate changes in overall drive shaft  20  length because shortened length in one portion of the drive shaft  20  may be compensated for by elongated length in another portion. The relative stiffness of the portions and the relative lengths of each portion may be selected to provide a length change balance between the two portions. Where the relative length change of each portion is substantially opposite and of the same magnitude, the distal end of the drive shaft  20  may maintain its position before, during, and after startup and when encountering an obstruction. As such, the abrasive element or crown  27  attached to a distal portion of the drive shaft  20  may be less likely or unlikely to jump or spring back (or forward) when loaded. Varying the lengths and filer diameters in certain embodiments of the present invention may allow for engineered and customized responses from a loaded drive shaft  20 . 
         [0026]    It is to be appreciated that while a two-part spin-to-open  20 A and spin-to-close  20 B system has been described, still other numbers of portions and combinations of spin-to-open  20 A and spin-to-close  20 B portions may be provided. For example, more than one spin-to-open  20 A section and/or more than one spin-to-close  20 B section, each section having a combination of fixed or varying filer diameters, counts and shaft diameters may be provided. 
         [0027]    As shown in  FIG. 6 , the proximal and distal portions  26 ,  28  of the drive shaft  20  may be secured to one another with a coupling element  32 . The coupling element  32  may include a sleeve type coupling element  32  such as a hypotube coupler with an inner diameter smaller than the outer diameter of the drive shaft  20  such that a portion of the drive shaft  20  may be turned down, step ground, or otherwise reduced in diameter and placed within the coupling element  32  for a friction fit. In other embodiments, in addition or in alternative to a friction fit, a welded, brazed, adhered, or other connection to the coupling element  32  may be provided. In still other embodiments, two adjoining drive shafts  26 ,  28  may be sleeved, one within the other, for a friction fit and/or welded, brazed, or adhered, for example. Still other coupling type connections such as those used to secure a crown  27  to the drive shaft  20  may be provided. For example, coupling connections and method such as those described in U.S. patent application Ser. No. 14/041,559 entitled Method of Attaching and Element to a Driveshaft filed on Sep. 30, 2013 may be provided. The contents of U.S. patent application Ser. No. 14/041,559 are hereby incorporated by reference herein in their entirety. The coupling element  32  arranged between one or more drive shaft portions  26 ,  28  may be relatively rigid or a more flexible coupling element  32  may be provided. 
         [0028]    Referring now to  FIG. 7 , multiple different features of particular portions of a drive shaft  120  may be selected such that the drive shaft  120  as a whole may perform in a particular manner. For example, as shown, a relatively stiff proximal portion  126  may be provided followed by a central portion  127  having a relatively flexible torsional stiffness and having a spin-to-open profile  120 A. Yet another portion  128  of the drive shaft may include an additional relatively flexible portion with a smaller diameter and having a spin-to-close  120 B or a spin-to-open  120 A profile. The atherectomy crown  127  may be positioned on this latter portion  128  which may be adapted to extend out of the distal end of the sheath  130  for purposes of addressing an occlusion or other obstruction. 
         [0029]    In the particular embodiment shown, the proximal portion  126  may, for example, include a multiple filer drive shaft such as a 6-filer section. Other numbers of filers including 5, 4, 3, 2, or 1 or numbers higher than 6 may also be used. This portion  126  of the drive shaft  120  may be a spin-to-close drive shaft  120 B, but its stiffness may be such that it refrains from locking down onto the guide wire  115  when activated or driven. 
         [0030]    The central portion  127  may include a relatively flexible spin-to-open profile  120 A. The spin-to-open profile  120 A may have a size and stiffness that is selected such that when actuated, the central portion  127  opens up and contacts the inside of the sheath  130 . In some embodiments, as shown, the at rest diameter  134  of the central portion  127  may be slightly larger than the diameter  136  of the proximal portion  126 . 
         [0031]    The distal portion  128  may include a relatively flexible spin-to-open  120 A or spin-to-close  120 B profile. For example, the distal portion  128  may include a soft flexible tip portion including a  3 -filer tip with a crown  127  positioned thereon. In some embodiments, as shown, the distal portion  128  may have a diameter  138  smaller than that of the central portion  127  and may also have a diameter  138  smaller than that of the proximal portion  126 . 
         [0032]    As shown, the varying diameters of the several portions  126 ,  127 , and  128  may be accommodated by providing coupling elements  132  in the form of reducers to transition from larger diameter portions to smaller diameter portions. In some embodiments, the outside of the reducers may be tapered as shown or a constant outside diameter with varying inside diameters may be provided. Still other approaches to coupling may be provided as discussed above. 
         [0033]    Several advantages may result from the combinations of different drive shaft properties along the length of the overall drive shaft. For example, the multi-direction winding design may provide reduced crown movement at startup. In addition, the multi-direction winding design may provide improved saline flow at higher rotational speeds. This is because spinning large diameter wires in a suitable direction may cause the wires to act as pump vanes functioning to advance the saline flow along the device within the sheath. Multi-direction winding provides the ability to tailor how the driveshaft reacts to overloading by allowing the driveshaft to expand and contact the saline sheath or to contract and contact the guide wire or a combination of both in different sections. Multi-direction winding design may provide different section properties to change stiffness or flexibility and, as such, affect the performance of a particular portion of the drive shaft and the overall performance. In some embodiments, several different filer cross-sectional shapes and areas may be used such as round, flat with edge radius, square, rectangle, etc. The areas may be adjusted by using heavy wire or fine wire or some variance in the thickness of the wire. The several different filer cross-sectional shapes and areas may be selected to provide a particular desired performance. In addition, as discussed with respect to  FIG. 7 , different number of filers can be used to change mechanical properties in each section of a drive shaft. In addition to varying the cross-sectional shape or area from one section of the drive shaft to another, the cross-sectional area may be varied within a single section by grinding, etching, stretching, or any other process known in the art to reduce or change the wire cross-sectional area or shape. 
         [0034]    It is to be appreciated that several factors have been discussed with respect to each portion of the drive shaft including spin-to-open, spin-to-close, cross-sectional shape and area, diameter, material, and variations of any of these within a particular portion. Selecting from these several factors may provide a drive shaft designer with a high level of flexibility to create a drive shaft with properties and/or performance characteristics never before seen or appreciated. With respect to any given property, the present application may include one of several combinations of arrangement potentially depending on the number of portions. For example, with respect to spin-to-open (SPO) and spin-to-close (SPC), if there are two portions of the drive shaft, there may be approximately four different arrangements that could be used from the proximal end to the distal end as follows:
       a. SPO; SPO   b. SPO; SPC   c. SPC; SPO   d. SPC; SPC       
 
         [0039]    As the number of portions of the drive shaft increases, all combinations of SPO and SPC shall be considered to be within the scope of the present disclosure. For example, where three portions are provided, the following arrangements may be provided:
       a. SPO; SPO; SPO   b. SPO; Spa; SPC   c. SPO; SPC; SPO   d. SPO; SPC; SPC   e. SPC; SPO; SPO   f. SPC; SPO; SPC   g. SPC; SPC; SPO   h. SPC; SPC; SPC       
 
         [0048]    Any number of portions may be provided and any combination of properties for the portions may be used. In cases where there is no change in the spin-to-open or spin-to-close profile from one section to another, there may be changes in other properties such as cross-sectional shape or area, diameter, or material, for example. With respect to the other properties and factors discussed, all combinations may also be provided. 
         [0049]    The present invention should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the invention. Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the present specification.