Patent Publication Number: US-2023149039-A1

Title: Atherectomy devices and methods

Description:
CLAIM OF PRIORITY 
     This is a continuation of U.S. Application Serial No. 17/592,797 filed on Feb. 4, 2022, which is a continuation of U.S. Application Serial No. 16/530,284 filed on Aug. 2, 2019 (now U.S. Pat. No. 11,272,954), which claims the benefit of U.S. Provisional Pat. Application Serial No. 62/715,643 filed on Aug. 7, 2018, the entire contents of which are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     This document relates to rotational atherectomy devices and systems with an electric motor that removes or reduces stenotic lesions in blood vessels, for example, by rotating an abrasive element within the vessel to partially or completely remove the stenotic lesion material. 
     BACKGROUND 
     Atherosclerosis, the clogging of arteries with plaque, is often a result of coronary heart disease or vascular problems in other regions of the body. Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood. Over time, the plaque hardens and narrows the arteries. This limits the flow of oxygen-rich blood to organs and other parts of the body. 
     Blood flow through the peripheral arteries (e.g., carotid, iliac, femoral, renal etc.), can be similarly affected by the development of atherosclerotic blockages. Peripheral artery disease (PAD) can be serious because without adequate blood flow, the kidneys, legs, arms, and feet may suffer irreversible damage. Left untreated, the tissue can die or harbor infection. 
     One method of removing or reducing such blockages in blood vessels is known as rotational atherectomy. In some implementations, a drive shaft carrying an abrasive burr or other abrasive surface (e.g., formed from diamond grit or diamond particles) rotates at a high speed within the vessel, and the clinician operator slowly advances the atherectomy device distally so that the abrasive burr scrapes against the occluding lesion and disintegrates it, reducing the occlusion and improving the blood flow through the vessel. 
     SUMMARY 
     Some embodiments of a rotational atherectomy device for removing stenotic lesion material from a blood vessel of a patient, includes: an elongate flexible drive shaft; an abrasive element coupled to a distal portion of the elongate flexible drive shaft; and a handle comprising an outer housing. The handle further includes an electric motor coupled to a proximal portion of the elongate flexible drive shaft, where the electric motor can be configured to cause rotation of the elongate flexible drive shaft in a first rotational direction. The device also includes a pump configured to provide fluid to a distal portion of the elongate flexible drive shaft, wherein the outer housing contains the electric motor and the pump. 
     In some embodiments, the rotational atherectomy device further comprises a control system configured to control rotation of the electric motor by monitoring an amount of current supplied to the electric motor and limiting the amount of current supplied such that the amount of current does not exceed a threshold current value. In some embodiments, the control system is configured to control rotation of the electric motor by initiating a stopping protocol when the amount of the current supplied reaches a threshold current value. In some embodiments, the stopping protocol comprises reducing the amount of current supplied to the electric motor to approximately zero. In some embodiments, the stopping protocol comprises reversing rotation of the elongate drive shaft by reversing the rotation caused by the electrical motor from the first rotational direction to a second rotational direction. In some embodiments, the stopping protocol occurs after a predetermined amount of time. In some embodiments, the predetermined amount of time is about 0.1 second to about 60 seconds. In some embodiments, the predetermined amount of time begins after the threshold current value is reached. In some embodiments, the elongate flexible drive shaft defines a longitudinal axis and comprising a torque-transmitting coil of one or more filars that are helically wound around the longitudinal axis in a second rotational direction, such that rotation of the elongate flexible drive shaft in the first rotational direction causes unwinding of the one or more filars of the elongate flexible drive shaft. 
     In some embodiments, the device further comprises a power source configured to couple to the handle. In some embodiments, the device further comprises a rechargeable battery removably coupled to the handle. In some embodiments, the handle further comprises a battery. In some embodiments, the handle further comprises a pump motor coupled to the pump and configured to run the pump. In some embodiments, the pump comprises at least one of a micropump, a piezoelectric pump, an electromechanical integrated pump, a peristaltic pump, or a quasiperistaltic pump. In some embodiments, the electric motor comprises at least one of a DC motor, or a DC motor controller. In some embodiments, the elongate flexible drive shaft is directly coupled to the electric motor. In some embodiments, the elongate flexible drive shaft is directly coupled to the electric motor via a cannulation in the electric motor. In some embodiments, the electric motor is coupled to the elongate flexible drive shaft in a gearless configuration. In some embodiments, the elongate flexible drive shaft is coupled to the electric motor via one or more gears. In some embodiments, the gear ratio is 2:1. 
     In some embodiments, a rotational atherectomy device for removing stenotic lesion material from a blood vessel of a patient, includes: an elongate flexible drive shaft defining a longitudinal axis and comprising a torque-transmitting coil; an abrasive element coupled to a distal portion of the elongate flexible drive shaft; and a handle. The handle comprises: an electric motor coupled to a proximal portion of the elongate flexible drive shaft, the electric motor configured to cause rotation of the elongate flexible drive shaft in a first rotational direction, such that rotation of the elongate flexible drive shaft in the first rotational direction causes unwinding of the elongate flexible drive shaft; and a control system configured to control rotation of the electric motor by monitoring an amount of current supplied to the electric motor; and limiting the amount of current supplied such that the amount of the current does not exceed a threshold current value. 
     In some embodiments, the torque-transmitting coil includes one or more filars that are helically wound around the longitudinal axis in a second rotational direction. In some embodiments, the control system is configured to control rotation of the electric motor by initiating a stopping protocol when the amount of the current supplied reaches a threshold current value. In some embodiments, the stopping protocol comprises reducing the amount of current supplied to the electric motor to approximately zero. In some embodiments, the stopping protocol comprises reversing rotation of the elongate drive shaft from the first rotational direction to the second rotational direction. In some embodiments, the device further comprises a power source configured to couple to the handle. In some embodiments, the device further comprises a rechargeable battery removably coupled to the handle. In some embodiments, the handle further comprises a battery. In some embodiments, the device further comprises a pump configured to provide fluid to a distal portion of the elongate flexible drive shaft. 
     In some embodiments, a method for performing rotational atherectomy to remove stenotic lesion material from a blood vessel of a patient, includes: delivering a rotational atherectomy device into the blood vessel. The rotational atherectomy device comprises: an elongate flexible drive shaft; an abrasive element coupled to a distal portion of the elongate flexible drive shaft; and a handle comprising an outer housing. The handle further comprises: an electric motor coupled to a proximal portion of the elongate flexible drive shaft, the electric motor configured to cause rotation of the elongate flexible drive shaft in a first rotational direction; and a pump configured to provide fluid to a distal portion of the elongate flexible drive shaft, wherein the outer housing contains the electric motor and the pump. The method further includes rotating the drive shaft about the longitudinal axis in the first rotational direction. 
     In some embodiments, a method for performing rotational atherectomy to remove stenotic lesion material from a blood vessel of a patient, includes: delivering a rotational atherectomy device into the blood vessel, and rotating the drive shaft about the longitudinal axis in the first rotational direction. The rotational atherectomy device comprises: an elongate flexible drive shaft defining a longitudinal axis and comprising a torque-transmitting coil; an abrasive element coupled to a distal portion of the elongate flexible drive shaft; and a handle, comprising: an electric motor coupled to a proximal portion of the elongate flexible drive shaft, the electric motor configured to cause rotation of the elongate flexible drive shaft in a first rotational direction, such that rotation of the elongate flexible drive shaft in the first rotational direction causes unwinding of the elongate flexible drive shaft; and a control system configured to control rotation of the electric motor. 
     In some embodiments, the torque-transmitting coil comprising one or more filars that are helically wound around the longitudinal axis in a second rotational direction. In some embodiments, the method further comprises: monitoring an amount of current supplied to the electric motor; and limiting the amount of current supplied such that the amount of the current does not exceed a threshold current value. In some embodiments, the method further comprises initiating a stopping protocol when the amount of the current supplied reaches a threshold current value. In some embodiments, the stopping protocol comprises at least one of reducing the amount of current supplied to the electric motor to approximately zero or reversing rotation of the elongate drive shaft from the first rotational direction to a second rotational direction. 
     In some embodiments, a rotational atherectomy device for removing stenotic lesion material from a blood vessel of a patient, includes: an elongate flexible drive shaft defining a longitudinal axis and comprising a torque-transmitting coil; an abrasive element coupled to a distal portion of the elongate flexible drive shaft; and a handle. The handle comprises: an electric motor coupled to a proximal portion of the elongate flexible drive shaft, the electric motor configured to cause rotation of the elongate flexible drive shaft in a first rotational direction, such that rotation of the elongate flexible drive shaft in the first rotational direction causes unwinding of the elongate flexible drive shaft; and a control system configured to control rotation of the electric motor by exclusively monitoring an amount of current supplied to the electric motor and limiting the amount of current supplied such that the amount of the current does not exceed a threshold current value. 
     In some embodiments, the threshold current value is configured to limit rotation of the elongate flexible drive shaft in the first rotational direction such that there is no unwinding of the one or more filars of the elongate flexible drive shaft. In some embodiments, the threshold current value is configured to limit rotation of the elongate flexible drive shaft in the first rotational direction such that there is no change in a maximum diameter of the elongate flexible drive shaft. 
     In some embodiments, a rotational atherectomy device for removing stenotic lesion material from a blood vessel of a patient, includes: an elongate flexible drive shaft; an abrasive element coupled to a distal portion of the elongate flexible drive shaft; and a handle comprising an outer housing. The handle further comprises: an electric motor comprising a cannula configured to receive the elongate flexible drive shaft, wherein the electric motor is coupled to a proximal portion of the elongate flexible drive shaft and configured to rotate the elongate flexible drive shaft in a first rotational direction. 
     Some of the embodiments described herein may provide one or more of the following advantages. First, some embodiments of the rotational atherectomy system are configured to advance the drive shaft and the handle assembly over a guidewire, and to use an electric motor to drive the rotation of the drive shaft while the guidewire remains within the drive shaft. Accordingly, in some embodiments the handle assemblies provided herein include features that allow the drive shaft to be positioned over a guidewire. Thereafter, the guidewire can be detained in relation to the handle so that the guidewire will not rotate while the drive shaft is being rotated. 
     Second, some embodiments of the rotational atherectomy system include a drive shaft constructed of one or more helically wound filars that are wound in the same direction that the drive shaft is rotated during use. Accordingly, the turns of the helically wound filars can tend to radially expand and separate from each other (or “open up”) during rotational use. Such a scenario advantageously reduces frictional losses between adjacent filar turns. Additionally, when a guidewire is disposed within the lumen defined by the helically wound filars during rotational use, the drive shaft will tend to loosen on the guidewire rather than to tighten on it. Consequently, in some cases no use of lubricant between the guidewire and the drive shaft is necessary. Moreover, since the drive shaft will tend to loosen on the guidewire, less stress will be induced on the guidewire during rotation of the drive shaft. Thus, the potential for causing breaks of the guidewire is advantageously reduced. Further, since the drive shaft will tend to loosen on the guidewire during use, a larger guidewire can be advantageously used in some cases. 
     Third, some embodiments of the rotational atherectomy devices and systems provided herein include multiple abrasive elements that are offset from each other around the drive shaft such that the centers of mass of the abrasive elements define a path that spirals around a central longitudinal axis of the drive shaft. In particular embodiments, the rotational atherectomy systems are used by rotating the drive shaft around the longitudinal axis in a direction opposite of the spiral path defined by the centers of mass of the abrasive elements. Such an arrangement can advantageously provide a smoother running and more controllable atherectomy procedure as compared to systems that rotate the drive shaft in the same direction as the spiral path defined by the centers of mass of the abrasive elements. 
     Fourth, some embodiments of the rotational atherectomy devices and systems provided herein include a handle assembly with an electric motor that is used to drive rotations of the drive shaft. Such an electric motor can be entirely or substantially entirely housed within the handle assembly of the rotational atherectomy devices. The electric motor can provide the benefits of providing increased control and reliability over the rotational movement of the shaft. Such benefits can improve the rotational responsiveness of rotational actuation of the shaft and can reduce or eliminate unintentional or excessive rotational actuation during an atherectomy procedure. Furthermore, the electric motor does not rely on pneumatic equipment, and therefore eliminates the burden of providing pneumatic power, such as a compressed gas (e.g., air, nitrogen, or the like) supply, during a medical procedure. Additionally, the handle assembly can incorporate or externally couple a control system for monitoring and controlling the rotation of the electric motor. 
     Fifth, certain embodiments of the handle assembly may integrate a pump or micropump, such as a saline pump (with a pump motor), within the housing. The pump can provide the benefit of delivering saline, or other fluids, to a distal end of the rotational atherectomy device, providing lubrication, and/or preventing blood from back flowing through a sheath of the rotational atherectomy device outside of the body. The integrated pump can increase the versatility of the handle assembly by eliminating the need to obtain and connect an external pump to the handle assembly during a medical procedure. 
     Also, by integrating the electric motor and pump into the handle assembly, additional advantages can be realized. For example, the handle assembly and/or the entire rotational atherectomy system provided herein can be sterilizable as well as disposable, thus reducing the risk of contamination and infection. 
     Sixth, the handle assembly can also house a battery, or couple to a battery. Such a device would not need external power to operate, making the rotational atherectomy device more readily available in remote areas with limited power supplies, or provide the user with increased convenience of use. As such, a clinician can have increased mobility with the handle assembly, as the handle assembly only needs to attach to an external fluid reservoir. Accordingly, a clinician would be less restricted and obstructed by connection cables during use. 
     Seventh, in some embodiments rotational atherectomy systems described herein include user controls that are convenient and easy to operate. In one such example, the user controls can include selectable elements on the handle assembly, reducing the need for a clinician to operate a secondary control device while operating the handle assembly. For example, the user controls can include selectable elements that correspond to the speed of drive shaft rotations. In some such examples, the user can conveniently select “low” or “high” speeds. Hence, in such a case the clinician-user conveniently does not need to explicitly select or control the rpm of the drive shaft. 
     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 
         FIG.  1    is a perspective view of an example rotational atherectomy system in accordance with some embodiments. 
         FIG.  2    is a top view of a handle assembly of the rotational atherectomy system of  FIG.  1    in accordance with some embodiments. 
         FIG.  3    is a perspective view of the handle assembly of  FIG.  2    in accordance with some embodiments. 
         FIG.  4    is an exploded view of the handle assembly of  FIG.  2    in accordance with some embodiments. 
         FIGS.  5 ,  6 , and  7 A- 7 B  are perspective views of an interior of the handle assembly of  FIG.  2    in accordance with some embodiments. 
         FIG.  8    is a schematic diagram representing an example drive shaft embodiment that includes filars that are wound in a direction opposite to a direction of a spiral path defined by multiple abrasive elements that are arranged at differing radial angles in accordance with some embodiments. 
         FIG.  9    is a schematic diagram representing another example drive shaft embodiment that includes filars that are wound in a direction opposite to the direction of a spiral path defined by multiple abrasive elements that are arranged at differing radial angles in accordance with some embodiments. 
         FIG.  10    is a longitudinal cross-sectional view of a distal portion of an example rotational atherectomy device showing a multi-portion abrasive element and a distal stability element with an abrasive coating, in accordance with some embodiments. 
         FIG.  11    is a side view of a distal portion of another example rotational atherectomy device showing a multi-portion abrasive element and a distal stability element with an abrasive coating, with an unwinding of the drive shaft (note that the figure shows unwinding in an exaggerated form for instructive purposes), in accordance with some embodiments. 
         FIG.  12    shows the example rotational atherectomy device of  FIGS.  10  or  11    in use at a first longitudinal position in the region of the lesion. A multi-portion abrasive element of the rotational atherectomy device is being rotated along an orbital path to abrade the lesion. 
         FIG.  13    shows the rotational atherectomy device of  FIGS.  10  or  11    with the abrasive element being rotated at a second longitudinal position that is distal of the first longitudinal position. 
         FIG.  14    shows the rotational atherectomy device of  FIGS.  10  or  11    with the abrasive element being rotated at a third longitudinal position that is distal of the second longitudinal position. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Referring to  FIG.  1   , in some embodiments a rotational atherectomy system  100  for removing or reducing stenotic lesions in blood vessels can include a guidewire  134 , a handle assembly  200 , and an elongate flexible drive shaft assembly  130 . The drive shaft assembly  130  extends distally from the handle assembly  200 . The handle assembly  200  can be operated by a clinician to perform and control the rotational atherectomy procedure. 
     In the depicted embodiment, the elongate flexible drive shaft assembly  130  includes a sheath  132  and a flexible drive shaft  136 . A proximal end of the sheath  132  is fixed to a distal end of the handle assembly  200 . The flexible drive shaft  136  is slidably and rotatably disposed within a lumen of the sheath  132 . The flexible drive shaft  136  defines a longitudinal lumen in which the guidewire  134  is slidably disposed. In this embodiment, the flexible drive shaft  136  includes a torque-transmitting coil that defines the longitudinal lumen along a central longitudinal axis, and the drive  136  shaft is configured to rotate about the longitudinal axis while the sheath  132  remains generally stationary. Hence, as described further below, during a rotational atherectomy procedure the flexible drive shaft  136  is in motion (e.g., rotating and longitudinally translating) while the sheath  132  and the guidewire  134  are generally stationary. 
     In some optional embodiments, an inflatable member (not shown) can surround a distal end portion of the sheath  132 . Such an inflatable member can be selectively expandable between a deflated low-profile configuration and an inflated deployed configuration. The sheath  132  may define an inflation lumen through which the inflation fluid can pass (to and from the optional inflatable member). The inflatable member can be in the deflated low-profile configuration during the navigation of the drive shaft assembly  130  through the patient’s vasculature to a target location in a vessel. Then, at the target location, the inflatable member can be inflated so that the outer diameter of the inflatable member contacts the wall of the vessel. In that arrangement, the inflatable member advantageously stabilizes the drive shaft assembly  130  in the vessel during the rotational atherectomy procedure. 
     Still referring to  FIG.  1   , the flexible driveshaft  136  is slidably and rotatably disposed within a lumen of the sheath  132 . A distal end portion of the driveshaft  136  extends distally of the distal end of the sheath  132  such that the distal end portion of the driveshaft  136  is exposed (e.g., not within the sheath  132 , at least not during the performance of the actual rotational atherectomy). 
     In the depicted embodiment, the exposed distal end portion of the driveshaft  136  includes one or more abrasive elements  138 , a (optional) distal stability element  140 , and a distal drive shaft extension portion  142 . In the depicted embodiment, the one or more abrasive elements  138  are eccentrically-fixed to the driveshaft  136  proximal of the distal stability element  140 . In this embodiment, the distal stability element  140  is concentrically-fixed to the driveshaft  136  between the one or more abrasive elements  138  and the distal drive shaft extension portion  142 . As such, the center of mass of the distal stability element  140  is aligned with the central axis of the drive shaft  136  while the center of mass of each abrasive element  138  is offset from the central axis of the drive shaft  136 . The distal drive shaft extension portion  142 , which includes the torque-transmitting coil, is configured to rotate about the longitudinal axis extends distally from the distal stability element  140  and terminates at a free end of the drive shaft  136 . 
     In some optional embodiments, a proximal stability element (not shown) is included. The proximal stability element can be constructed and configured similarly to the depicted embodiment of the distal stability element  140  (e.g., a metallic cylinder directly coupled to the torque-transmitting coil of the drive shaft  136  and concentric with the longitudinal axis of the drive shaft  136 ) while being located proximal to the one or more abrasive elements  138 . 
     In the depicted embodiment, the distal stability element  140  has a center of mass that is axially aligned with a central longitudinal axis of the drive shaft  136 , while the one or more abrasive elements  138  (collectively and/or individually) have a center of mass that is axially offset from central longitudinal axis of the drive shaft  136 . Accordingly, as the drive shaft  136  is rotated about its longitudinal axis, the principle of centrifugal force will cause the one or more abrasive elements  138  (and the portion of the drive shaft  136  to which the one or more abrasive elements  138  are affixed) to follow a transverse generally circular orbit (e.g., somewhat similar to a “jump rope” orbital movement) relative to the central axis of the drive shaft  136 . In general, faster speeds (rpm) of rotation of the drive shaft  136  will result in larger diameters of the orbit (within the limits of the vessel diameter). The orbiting one or more abrasive elements  138  will contact the stenotic lesion to ablate or abrade the lesion to a reduced size (i.e., small particles of the lesion will be abraded from the lesion). 
     The rotating distal stability element  140  will remain generally at the longitudinal axis of the drive shaft  136  as the drive shaft  136  is rotated. In some optional embodiments, two or more distal stability elements  140  are included. As described further below, contemporaneous with the rotation of the drive shaft  136 , the drive shaft  136  can be translated back and forth along the longitudinal axis of the drive shaft  136 . Hence, lesions can be abraded radially and longitudinally by virtue of the orbital rotation and translation of the one or more abrasive elements  138 , respectively. 
     The flexible drive shaft  136  of rotational atherectomy system  100  is laterally flexible so that the drive shaft  136  can readily conform to the non-linear vasculature of the patient, and so that a portion of the drive shaft  136  at and adjacent to the one or more abrasive elements  138  will laterally deflect when acted on by the centrifugal forces resulting from the rotation of the one or more eccentric abrasive elements  138 . In this embodiment, the drive shaft  136  comprises one or more helically wound wires (or filars) that provide one or more torque-transmitting coils of the drive shaft  136  (as described below, for example, in connection with  FIGS.  8 - 11   ). In some embodiments, the one or more helically wound wires are made of a metallic material such as, but not limited to, stainless steel (e.g., 316, 316L, or 316LVM), nitinol, titanium, titanium alloys (e.g., titanium beta 3), carbon steel, or another suitable metal or metal alloy. In some alternative embodiments, the filars are or include graphite, Kevlar, or a polymeric material. In some embodiments, the filars can be woven, rather than wound. In some embodiments, individual filars can comprise multiple strands of material that are twisted, woven, or otherwise coupled together to form a filar. In some embodiments, the filars have different cross-sectional geometries (size or shape) at different portions along the axial length of the drive shaft  136 . In some embodiments, the filars have a cross-sectional geometry other than a circle, e.g., an ovular, square, triangular, or another suitable shape. 
     In this embodiment, the drive shaft  136  has a hollow core. That is, the drive shaft  136  defines a central longitudinal lumen running therethrough. The lumen can be used to slidably receive the guidewire  134  therein, as will be described further below. In some embodiments, the lumen can be used to aspirate particulate or to convey fluids that are beneficial for the atherectomy procedure. 
     In some embodiments, the drive shaft  136  includes an optional coating on one or more portions of the outer diameter of the drive shaft  136 . The coating may also be described as a jacket, a sleeve, a covering, a casing, and the like. In some embodiments, the coating adds column strength to the drive shaft  136  to facilitate a greater ability to push the drive shaft  136  through stenotic lesions. In addition, the coating can enhance the rotational stability of the drive shaft  136  during use. In some embodiments, the coating is a flexible polymer coating that surrounds an outer diameter of the coil (but not the abrasive elements  138  or the distal stability element  140 ) along at least a portion of drive shaft  136  (e.g., the distal portion of the drive shaft  136  exposed outwardly from the sheath  132 ). In some embodiments, a portion of the drive shaft  136  or all of the drive shaft  136  is uncoated. In particular embodiments, the coating is a fluid impermeable material such that the lumen of the drive shaft  136  provides a fluid impermeable flow path along at least the coated portions of the drive shaft  136 . 
     The coating may be made of materials including, but not limited to, PEBEX, PICOFLEX, PTFE, ePTFE, FEP, PEEK, silicone, PVC, urethane, polyethylene, polypropylene, and the like, and combinations thereof. In some embodiments, the coating covers the distal stability element  140  and the distal extension portion  142 , thereby leaving only the one or more abrasive elements  138  exposed (non-coated) along the distal portion of the drive shaft  136 . In alternative embodiments, the distal stability element  140  is not covered with the coating, and thus would be exposed like the abrasive element  140 . In some embodiments, two or more layers of the coating can be included on portions of the drive shaft  136 . Further, in some embodiments different coating materials (e.g., with different durometers and/or stiffnesses) can be used at different locations on the drive shaft  136 . 
     In the depicted embodiment, the distal stability element  140  is a metallic cylindrical member having an inner diameter that surrounds a portion of the outer diameter of the drive shaft  136 . In some embodiments, the distal stability element  140  has a longitudinal length that is greater than a maximum exterior diameter of the distal stability element  140 . In the depicted embodiment, the distal stability element  140  is coaxial with the longitudinal axis of the drive shaft  136 . Therefore, the center of mass of the distal stability element  140  is axially aligned (non-eccentric) with the longitudinal axis of the drive shaft  136 . In alternative rotational atherectomy device embodiments, stability element(s) that have centers of mass that are eccentric in relation to the longitudinal axis may be included in addition to, or as an alternative to, the coaxial stability elements  140 . For example, in some alternative embodiments, the stability element(s) can have centers of mass that are eccentric in relation to the longitudinal axis and that are offset 180 degrees (or otherwise oriented) in relation to the center of mass of the one or more abrasive elements  138 . 
     The distal stability element  140  may be made of a suitable biocompatible material, such as a higher-density biocompatible material. For example, in some embodiments the distal stability element  140  may be made of metallic materials such as stainless steel, tungsten, molybdenum, iridium, cobalt, cadmium, and the like, and alloys thereof. The distal stability element  140  has a fixed outer diameter. That is, the distal stability element  140  is not an expandable member in the depicted embodiment. The distal stability element  140  may be mounted to the filars of the drive shaft  136  using a biocompatible adhesive, by welding, by press fitting, and the like, and by combinations thereof. The coating may also be used in some embodiments to attach or to supplement the attachment of the distal stability element  140  to the filars of the drive shaft  136 . Alternatively, the distal stability element  140  can be integrally formed as a unitary structure with the filars of the drive shaft  136  (e.g., using filars of a different size or density, using filars that are double-wound to provide multiple filar layers, or the like). The maximum outer diameter of the distal stability element  140  may be smaller than the maximum outer diameters of the one or more abrasive elements  138 . 
     In some embodiments, the distal stability element  140  has an abrasive coating on its exterior surface. For example, in some embodiments a diamond coating (or other suitable type of abrasive coating) is disposed on the outer surface of the distal stability element  140 . In some cases, such an abrasive surface on the distal stability element  140  can help facilitate the passage of the distal stability element  140  through vessel restrictions (such as calcified areas of a blood vessel). 
     In some embodiments, the distal stability element  140  has an exterior cylindrical surface that is smoother and different from an abrasive exterior surface of the one or more abrasive elements  138 . That may be the case whether or not the distal stability element  140  have an abrasive coating on its exterior surface. In some embodiments, the abrasive coating on the exterior surface of the distal stability element  140  is rougher than the abrasive surfaces on the one or more abrasive elements  138 . 
     Still referring to  FIG.  1   , the one or more abrasive elements  138  (which may also be referred to as a burr, multiple burrs, or (optionally) a helical array of burrs) can comprise a biocompatible material that is coated with an abrasive media such as diamond grit, diamond particles, silicon carbide, and the like. In the depicted embodiment, the abrasive elements  138  includes a total of five discrete abrasive elements that are spaced apart from each other. In some embodiments, one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, or more than fifteen discrete abrasive elements are included as the one or more abrasive elements  138 . Each of the five discrete abrasive elements can include the abrasive media coating, such as a diamond grit coating. 
     In the depicted embodiment, the two outermost abrasive elements are smaller in maximum diameter than the three inner abrasive elements. In some embodiments, all of the abrasive elements are the same size. In particular embodiments, three or more different sizes of abrasive elements are included. Any and all such possible arrangements of sizes of abrasive elements are envisioned and within the scope of this disclosure. 
     Also, in the depicted embodiment, the center of mass of each abrasive element  138  is offset from the longitudinal axis of the drive shaft  136 . Therefore, as the eccentric one or more abrasive elements  138  are rotated (along an orbital path), at least a portion of the abrasive surface of the one or more abrasive elements  138  can make contact with surrounding stenotic lesion material. As with the distal stability element  140 , the eccentric one or more abrasive elements  138  may be mounted to the filars of the torque-transmitting coil of the drive shaft  136  using a biocompatible adhesive, high temperature solder, welding, press fitting, and the like. In some embodiments, a hypotube is crimped onto the driveshaft and an abrasive element is laser welded to the hypotube. Alternatively, the one or more abrasive elements  138  can be integrally formed as a unitary structure with the filars of the drive shaft  136  (e.g., using filars that are wound in a different pattern to create an axially offset structure, or the like). 
     In some embodiments, the spacing of the distal stability element  140  relative to the one or more abrasive elements  138  and the length of the distal extension portion  142  can be selected to advantageously provide a stable and predictable rotary motion profile during high-speed rotation of the drive shaft  136 . For example, in embodiments that include the distal driveshaft extension portion  142 , the ratio of the length of the distal driveshaft extension  142  to the distance between the centers of the one or more abrasive elements  138  and the distal stability element  140  is about 1:0.5, about 1:0.8, about 1:1, about 1.1:1, about 1.2:1, about 1.5:1, about 2:1, about 2.5:1, about 3:1, or higher than 3:1. 
     Still referring to  FIG.  1   , and further referring to  FIGS.  2  and  3   , the rotational atherectomy system  100  also includes the handle assembly  200 . The handle assembly  200  includes a housing  202  and a carriage assembly  204 . The carriage assembly  204  is slidably translatable along the longitudinal axis of the handle assembly  200  along an aperture  205  defining a path, such that carriage assembly  204  along the longitudinal axis as indicated by the arrow  115 . For example, in some embodiments the carriage assembly  204  can be translated, without limitation, about 8 cm to about 12 cm, or about 6 cm to about 10 cm, or about 4 cm to about 8 cm, or about 6 cm to about 14 cm. As the carriage assembly  204  is translated in relation to the housing  202 , the drive shaft  136  translates in relation to the sheath  132  in a corresponding manner. 
     In the depicted embodiment, the carriage assembly  204  includes an electrical motor switch  206 . While the electrical motor switch  206  is depressed, power is supplied to the electric motor (as shown in  FIGS.  4 - 6 , and  7 A- 7 B ) which is fixedly coupled to the drive shaft  136 . Hence, an activation of the electrical motor switch  206  will result in a rotation of the turbine member and, in turn, the drive shaft  136  (as depicted by arrow  137 ). It should be understood that the rotational atherectomy system  100  is configured to rotate the drive shaft  136  at a high speed of rotation (e.g., 20,000-160,000 rpm) such that the eccentric one or more abrasive elements  138  revolve in an orbital path to thereby contact and remove portions of a target lesion (even those portions of the lesion that are spaced farther from the axis of the drive shaft  136  than the maximum radius of the one or more abrasive elements  138 ). 
     To operate the handle assembly  200  during a rotational atherectomy procedure, a clinician can grasp the carriage assembly  204  and depress the electrical motor switch  206  with the same hand. The clinician can move (translate) the carriage assembly  204  distally and proximally by hand (e.g., back and forth in relation to the housing  202 ), while maintaining the electrical motor switch  206  in the depressed state. In that manner, a target lesion(s) can be ablated radially and longitudinally by virtue of the resulting orbital rotation and translation of the one or more abrasive elements  138 , respectively. 
     To further operate the handle assembly  200  during a rotational atherectomy procedure, a clinician can select a rotational speed using electrical switches  210   a  and  210   b . In some cases, the rotational speed can be selected through a range of speeds with electrical switch  210   a  causing an increase in speed and electrical switch  210   b  causing a decrease in speed. In some embodiments, rotational speed is changed incrementally between a plurality of preset speeds. For example, a single depression of electrical switch  210   a  or  210   b  will cause an incremental change in speed. In some embodiments, depression of the electrical switch  210   a  or  210   b  will cause a change in speed corresponding to a length of time that the electrical switch  210   a  or  210   b  is depressed. In another embodiment, the electrical switch  210   a  will cause a selection of a “high” rotational speed and the electrical switch  210   b  will cause a selection of a “low” rotational speed, in comparison to the high rotational speed. 
     Optionally, the electrical switches  210   a  and  210   b  can also include a light indicator. For example, when the electrical switches  210   a  and  210   b  allow for selection for a “high” and “low” speed, respectively, the electrical switches  210   a  and  210   b  can each have a single light, such that when a speed is selected, the light corresponding to the selected electrical switch  210   a  or  210   b  is illuminated to inform a clinician of the selected speed. In some embodiments, the light can shine through electrical switches  210   a  and  210   b . Alternatively, a light can be positioned proximal electrical switch  210   a  and  210   b . As another example, when the electrical switches  210   a  and  210   b  allow modification of a speed between a range of speeds, the light indicator can be a light bar, such that a number of lights illuminated on the light bar correspond to a selected speed. 
     Optionally, handle assembly  200  can include an electrical pump switch  212 . Electrical pump switch  212  can turn a saline pump on and off. In some cases, a first depression of the electrical pump switch  212  will turn the saline pump on, while a second depression will turn the saline pump on. In some embodiments, the electrical pump switch  212  includes a light indicator, such that when the pump is on, a light is illuminated to inform the clinician that the pump is on. 
     During an atherectomy treatment, in some cases the guidewire  134  is left in position in relation to the drive shaft  136  generally as shown. For example, in some cases the portion of the guidewire  134  that is extending beyond the distal end of the drive shaft  136  (or extension portion  142 ) is about 10 inches to about 12 inches (about 25 cm to about 30 cm), about 6 inches to about 16 inches (about 15 cm to about 40 cm), or about 2 inches to about 20 inches (about 5 cm to about 50 cm). In some cases, the guidewire  134  is pulled back to be within (while not extending distally from) the drive shaft  136  during an atherectomy treatment. The distal end of the guidewire  134  may be positioned anywhere within the drive shaft  136  during an atherectomy treatment. In some cases, the guidewire  134  may be completely removed from within the drive shaft during an atherectomy treatment. The extent to which the guidewire  134  is engaged with the drive shaft  136  during an atherectomy treatment may affect the size of the orbital path of the one or more abrasive elements  138 . Accordingly, the extent to which the guidewire  134  is engaged with the drive shaft  136  may be situationally selected to be well-suited for a particular patient anatomy, physician’s preference, type of treatment being delivered, and other such factors. 
     In the depicted embodiment, the handle assembly  200  also includes a guidewire detention mechanism  208 . The guidewire detention mechanism  208  can be selectively actuated (e.g., rotated) to releasably clamp and maintain the guidewire  134  in a stationary position relative to the handle assembly  200  (and, in turn, stationary in relation to rotations of the drive shaft  136  during an atherectomy treatment). While the drive shaft  136  and handle assembly  200  are being advanced over the guidewire  134  to put the one or more abrasive elements  138  into a targeted position within a patient’s vessel, the guidewire detention mechanism  208  will be unactuated so that the handle assembly  200  is free to slide in relation to the guidewire  134 . Then, when the clinician is ready to begin the atherectomy treatment, the guidewire detention mechanism  208  can be actuated to releasably detain/lock the guidewire  134  in relation to the handle assembly  200 . That way the guidewire  134  will not rotate while the drive shaft  136  is rotating, and the guidewire  134  will not translate while the carriage assembly  204  is being manually translated. 
     In some embodiments, when the guidewire detention mechanism  208  is actuated to detain/lock the guidewire  134 , a light indicator  214  can illuminate, such that a clinician can confirm the guidewire detention mechanism  208  is actuated. 
     Optionally, the handle assembly  200  can include a safety mechanism regarding operation of the handle assembly. For example, rotation of the drive shaft assembly  130  may be prohibited until the guidewire detention mechanism  208  is actuated, the pump has been turned on via electrical pump switch  212 , and a rotation speed has been selected via electrical switch  210   a  or  210   b . As another example, the indicator lights associated with the electrical switch  210   a  or  210   b , the electrical pump switch  212 , and the guidewire detention mechanism  208  light indicator  214  will alert a clinician that the rotational atherectomy system  100  should not be operated until all three systems (the motor, the pump, the guidewire lock) are lit. For example, each system may have a green light, such that three green lights indicates the clinician can proceed with the atherectomy procedure. Optionally, only the guidewire detection mechanism  208  needs to be actuated to allow rotation of the rotational atherectomy system  100 . 
     Referring to  FIGS.  4 - 6 , and  7 A- 7 B , an interior cavity  201  of the handle assembly  200  is shown. The housing  202  can include an upper housing  202   a  and a lower housing  202   b  that encapsulate a motor assembly  220 , a pump assembly  230 , and a controller assembly  240 . The interior cavity  201  can also house the electrical switches  210   a  and  210   b , the electrical pump switch  212 , and the light indicator  214 , collectively, user controls  216 . In some cases, the user controls  216  can protrude through apertures of upper housing  202   a . In some embodiments, the user controls  216  can abut a flexible portion of upper housing  202   a , such that the user controls  216  can be actuated without direct contact. In some embodiments, the handle assembly  200  is disposable. In some embodiments, the handle assembly  200  is a sterilized handle assembly, or is partially or fully sterilizable handle assembly. For example, in some embodiments, the handle can be sterilized using ethylene oxide (EtO) sterilization, or hydrogen peroxide sterilization. 
     The motor assembly  220  can include a motor  222  and, optionally, a gear assembly  224  (as shown in  FIG.  7 A ). The motor  222  can be electric motor, such as a DC motor. Exemplary motors can include a brush DC motor, or a brushless DC motor. Other suitable motors may, however, include a servo motor, a stepper motor, and/or an AC motor. Motor  222  can be mechanically coupled to carriage assembly  204 , such that motor  222  can translate along housing  202 , and more specifically, inside sheath  132  to cause translation of drive shaft  136 . Further, motor  222  can be electrically coupled to electrical motor switch  206 , such that depression of electrical motor switch  206  causes motor  222  to run. In some embodiments, motor  222  can be directly coupled to drive shaft  136  to cause rotation of drive shaft  136 , and accordingly, abrasive elements  138 . For example, the motor  222  can include a cannulation through a longitudinal axis of the motor  222  that is configured to receive and secure the drive shaft  136 , direct drive of the drive shaft  136 . 
     As mentioned above, motor assembly  220  can include a gear assembly  224 . In some embodiments, the gear assembly  224  can have a 2:1 gear ratio to increase an rpm output from motor  222 . In some cases, using a motor with lower rpm capabilities, but supplementing the motor  222  with the gear assembly  224  can be more cost effective, especially for a disposable handle assembly  200 . For example, motor  222  can have an output of 40k rpm, and can cause rotation of the drive shaft  136  at 80k rpm. Motor  222  can be controlled by controller assembly  240 , as will be described below. 
     In another embodiment, as shown in  FIG.  7 B , motor assembly  220  can include a cannulated motor  226 . Cannulated motor  226  can include a cannulation to receive a hypotube of the rotational atherectomy device. In some embodiments, the cannulated motor  226  can provide a simpler design, which can reduce breakage by reducing the number of components involved in rotation of the elongate flexible drive shaft. Further, direct translation of the rotational components can increase simplicity of the design and operation of the rotational atherectomy device. Cannulated motor  226  can provide the improved torque transmission during the rotation of the elongate flexible drive shaft. 
     The pump assembly  230  can include a pump  232  (or micropump), tubes  234 , an external fitting  236 , and a pump motor  238 . Pump  232  can pump saline, or other fluids, to a distal portion of rotational atherectomy device  100 . Pump  232  can be a peristaltic pump, a piezoelectric pump, an electromechanical integrated pump, a microdosing pump, a positive displacement pump, a quasi-peristaltic pump, or other micropump. Pump  232  can include one or more tubes  234  extend from, or extending through, pump  232  to pump saline from an exterior of housing  202  to a distal end of the rotational atherectomy device  100 . In some embodiments, due to sterilization needs, it can be beneficial to use a pump with separation between the fluid and pump  232 , such that the fluid only contacts tubes  234 . External fitting  236  can couple to tube  234  and further couple to a tube external to housing  202 . For example, external fitting  236  can be a luer fitting to couple a fluid bag (e.g., a saline bag). Pump  232  can be powered by pump motor  238 , which can be controlled by controller assembly  240 . Optionally, pump motor  238  can be a brushless DC motor. Pump motor  238  can allow pump  232  to operate at about 3.5 psi to about 4 psi, such that the fluid pumped by pump  232  prevents backflow of blood during the atherectomy procedure. Pump assembly  230  can include seals to prevent leakage into housing  202 . 
     The controller assembly  240  can include a housing  242 , and a controller  244 . Housing  242  can provide a seal and barrier between controller  244  and the other components of handle assembly  200  to protect the controller  244  from liquid (e.g., blood from a patient, fluid from the pump  232 ). In some embodiments, the housing  242  can also provide a structural support for the pump assembly  230 , as shown in  FIGS.  5 - 7   . The controller  244  can be electrically coupled to the components of the user controls  216  and control function of the components. 
     For example, the controller  244  can cause motor  222  to run or stop based on electrical motor switch  206 , such that when electrical motor switch  206  is depressed, controller  244  causes motor  222  to run. In addition, controller  244  can determine and control a speed for rotating the drive shaft  136 , and supply the appropriate power to the motor  222  based on user input via electrical switches  210   a  and/or  210   b . For example, the rotational speed can be selected through a range of speeds with electrical switch  210   a  causing an increase in speed and electrical switch  210   b  causing a decrease in speed. In some embodiments, rotational speed is changed incrementally between a plurality of preset speeds. As such, a single depression of electrical switch  210   a  or  210   b  can cause controller  244  to increase current supplied to the motor  222  to cause an incremental change in speed. In some embodiments, depression of the electrical switch  210   a  or  210   b  will cause controller  244  to supply a current to cause a change in speed corresponding to a length of time that the electrical switch  210   a  or  210   b  is depressed. In another embodiment, the electrical switch  210   a  will cause controller  244  to determine a selection of a “high” rotational speed was made and provide the appropriate current, and the electrical switch  210   b  will cause controller  244  to determine a selection of a “low” rotational speed, in comparison to the high rotational speed, was made and provide the appropriate current. Additionally, controller  244  can control the light indicators associated with electrical switches  210   a  and  210   b , as described above. 
     In some embodiments, the controller  244  can monitor and control a parameter, such as an amount of current supplied to the motor  222 . Such monitoring and controlling features can provide a safety (shut-off) feature to the rotational atherectomy system  100  that prevents damage from occurring to the system  100  and/or a patient during use. For example, in various embodiments, the controller  244  is configured such that the current supplied does not exceed a threshold current value (e.g., prevents a large amount of current from being supplied to motor  222 ). Thus, the controller  244  can be programmed to provide current to the motor  222 , but at a current level that is no greater than the threshold current value. The controller  244  can optionally limit the system  100  based exclusively on the current threshold value, in some embodiments, to provide an effective, yet simplified algorithm to the controller  244  as a safety feature. 
     The threshold current value can be a predetermined value that prevents irreversible damage or undesirable performance of the system  100  from occurring during use. For example, in some embodiments, the threshold current value is configured to limit the torque and/or speed of rotation of the system  100  such that the rotation of the elongate flexible drive shaft in a particular rotational direction (e.g., a first rotational direction) does not cause unwinding of the one or more filars of the elongate flexible drive shaft to occur. In some embodiments, the threshold current value is configured to limit the torque and/or speed of rotation of the system  100  such that the rotation of the elongate flexible drive shaft in a particular rotational direction (e.g., a first rotational direction) does not cause a change in a maximum diameter of the elongate flexible drive shaft to occur. 
     In some embodiments, if the current supplied reaches a threshold current value, the controller  244  can initiate a stopping protocol. For example, the stopping protocol can cause the controller  244  to reduce the amount of current supplied to the electrical motor to approximately zero. In some embodiments, such a reduction of current supplied can occur in a short period of time, substantially instantaneously, or over a longer period of time. In some embodiments, the stopping protocol can cause the controller  244  to reverse the direction of rotation of the motor  222 , and therefore the rotation of the drive shaft  136 . Such a reversal in direction of rotation of the drive shaft  136  can cause rotation of a distal end of the drive shaft to  136  to slow down or stop. The stopping protocol can aid in preventing motor  222  from burning out. In some cases, the stopping protocol is caused to a distal portion of drive shaft  136  being stuck in a vessel. Optionally, once rotation has begun, the stopping protocol can be executed after a predetermined amount of time (e.g., about 0.1 seconds to about 60 seconds). In some cases, the predetermined amount of time for executing the stopping protocol can be selected such that the predetermined amount of time begins when the current threshold is reached. For example, the drive shaft coil may begin to unwind once the current threshold is reached, and the controller may continue to provide current to the motor until the predetermined amount of time has passed. In some cases, the drive shaft coil may begin to unwind before the current threshold is reached, and the controller will continue to motor the current supplied and initiate the stopping protocol after the current threshold is reached. 
     Optionally, controller  244  can cause pump motor  238  to run or stop pump  232  based on depression of electrical pump switch  212 . In some cases, a first depression of the electrical pump switch  212  will turn the saline pump on, while a second depression will turn the saline pump on. In some embodiments, the controller  244  control the light indicator associated with electrical pump switch  212 , such that when the pump is on, a light is illuminated to inform the clinician that the pump is on. 
     In some embodiments, controller  244  can monitor guidewire detention mechanism  208  (e.g., via a sensor), such that controller  244  can determine when guidewire detention mechanism  208  is actuated (e.g., rotated) to releasably clamp and maintain the guidewire  134  in a stationary position relative to the handle assembly  200  (and, in turn, stationary in relation to rotations of the drive shaft  136  during an atherectomy treatment). In some embodiments, when the clinician is ready to begin the atherectomy treatment, the guidewire detention mechanism  208  can be actuated to releasably detain/lock the guidewire  134  in relation to the handle assembly  200 . That way the guidewire  134  will not rotate while the drive shaft  136  is rotating, and the guidewire  134  will not translate while the carriage assembly  204  is being manually translated. Accordingly, controller  244  can prevent motor  222  from rotating the drive shaft  136  unless controller  244  detects that the guidewire detention mechanism  208  is actuated. Further, controller  244  can control illumination of the light indicator  214 . 
     Optionally, the controller  244  can include a safety mechanism regarding operation of the handle assembly  200 . For example, rotation of the drive shaft assembly  130  may be prohibited until the controller  244  detects that guidewire detention mechanism  208  is actuated, the pump has been turned on via electrical pump switch  212 , and a rotation speed has been selected via electrical switch  210   a  or  210   b . As another example, the controller  244  can selectively illuminate indicator lights associated with the electrical switch  210   a  or  210   b , the electrical pump switch  212 , and the guidewire detention mechanism  208  light indicator  214  to inform a clinician which systems are powered on. In some embodiments, a lack of three lights indicts to the clinician that the rotational atherectomy system  100  should not be operated, at least until all three systems (the motor, the pump, the guidewire lock) are lit. For example, each system may have a green light, such that three green lights indicates the clinician can proceed with the atherectomy procedure. Optionally, only the guidewire detection mechanism  208  needs to be actuated for the controller  244  to allow rotation of the rotational atherectomy system  100 . 
     In some embodiments, the handle assembly  200  can also include a battery or other power source (not shown). The battery or power source may be integrated into the housing  202 . For example, the battery could be disposable with handle assembly  200 . In some embodiments, the power source could have an external component configured to make an electrical connection (e.g., plug into a wall socket) to provide power. Optionally, the battery could be reusable. For example, housing  202  can be configured to receive a rechargeable battery, either on an exterior portion of housing  202 , or within interior cavity  201 . 
     Referring to  FIG.  8   , a schematic diagram  150   a  depicting an end view of the drive shaft  136  (looking distally) with the abrasive elements  138  can be used to illustrate the filar spiral wind direction  131   a  (of the drive shaft  136 ) in comparison to the spiral path defined by the abrasive element centers of mass  133   a  (of the abrasive elements  138  of  FIG.  10   , and the abrasive elements144a-e of  FIG.  11   ), and also in comparison to the rotation direction  145   a  of the drive shaft  136  during use. In the depicted embodiment, the filar spiral wind direction  131   a  is clockwise around the central longitudinal axis  135  of the drive shaft  136 . Also, the rotation direction  145   a  of the drive shaft  136  during use is clockwise around the central longitudinal axis  135  of the drive shaft  136 . In contrast, the spiral path defined by the abrasive element centers of mass  133   a  is counterclockwise around the central longitudinal axis  135  of the drive shaft  136 . In other words, the filar spiral wind direction  131   a  and the rotation direction  145   a  of the drive shaft  136  during use are the same direction, whereas the spiral path defined by the abrasive element centers of mass  133   a  is the opposite direction of: (i) the filar spiral wind direction  131   a  and (ii) the opposite direction of the rotation direction  145   a  of the drive shaft  136  during use. 
     Referring also to  FIG.  9   , another schematic diagram  150   b  depicting an end view of the drive shaft  136  (looking distally) with the abrasive elements  144   a - e  (as shown in  FIG.  11   ) can be used to illustrate another arrangement of the filar spiral wind direction  131   b  (of the drive shaft  136 ) in comparison to the spiral path defined by the abrasive element centers of mass  133   b  (of the abrasive elements  144   a - e ), and also in comparison to the rotation direction  145   b  of the drive shaft  136  during use. In the depicted embodiment, the filar spiral wind direction  131   b  is counterclockwise around the central longitudinal axis  135  of the drive shaft  136 . Also, the rotation direction  145   b  of the drive shaft  136  during use is counterclockwise around the central longitudinal axis  135  of the drive shaft  136 . In contrast, the spiral path defined by the abrasive element centers of mass  133   b  is clockwise around the central longitudinal axis  135  of the drive shaft  136 . In other words, here again in this example, the filar spiral wind direction  131   b  and the rotation direction  145   b  of the drive shaft  136  during use are the same direction, whereas the spiral path defined by the abrasive element centers of mass  133   b  is the opposite direction of: (i) the filar spiral wind direction  131   b  and (ii) the opposite direction of the rotation direction  145   b  of the drive shaft  136  during use. 
     The relative arrangements between: (i) the filar spiral wind direction  131   a  or  131   b , (ii) the spiral path defined by the abrasive element centers of mass  133   a  or  133   b , and (iii) the rotation direction  145   a  or  145   b  of the drive shaft  136  during use, as described above in reference to  FIGS.  9  and  10   , provide particular operational advantages in some usage scenarios. For example, when the direction of rotation and the direction the filars are wound are the same direction, the winds of the filars will tend to radially expand (the drive shaft  136  will tend to “open up,” as shown in  FIGS.  10  and  11   ), resulting in less friction, little to no need for lubrication, less stress induced on the guidewire, and so on. Additionally, when the direction of rotation of the drive shaft  136  and the direction of the spiral path defined by the centers of mass of the abrasive elements  144  are opposite, such an arrangement can advantageously provide a smoother running and more controllable atherectomy procedure as compared to systems that rotate the drive shaft in the same direction as the spiral path defined by the centers of mass of the abrasive elements. For example, rather than causing the abrasive elements  144  to corkscrew into the stenotic lesion material (as can occur when the drive shaft rotational direction is the same as the direction of the spiral path defined by the centers of mass of the abrasive elements), the abrasive elements  144  can instead abrade the stenotic lesion material in more of a gradual, smooth, and controllable manner. 
     Referring to  FIG.  10   , a distal end portion of the drive shaft  136  is shown in a longitudinal cross-sectional view. The distal end portion of the drive shaft  136  includes the one or more abrasive elements  138  that are eccentrically-fixed to the driveshaft  136 , the optional distal stability element  140  with an abrasive outer surface, and the distal drive shaft extension portion  142 . 
     In the depicted embodiment, the one or more abrasive elements  138  includes a total of five discrete abrasive elements that are spaced apart from each other. In some embodiments, one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, or more than fifteen discrete abrasive elements are included as the one or more abrasive elements  138 . Each of the five discrete abrasive elements can include the abrasive media coating. 
     In the depicted embodiment, the two outermost abrasive elements of the abrasive elements  138  are smaller in maximum diameter than the three inner abrasive elements of the abrasive elements  138 . In some embodiments, all of the abrasive elements are the same size. In particular embodiments, three or more different sizes of abrasive elements are included. Any and all such possible arrangements of sizes of abrasive elements are envisioned and within the scope of this disclosure. 
     The one or more abrasive elements  138  can be made to any suitable size. For clarity, the size of the one or more abrasive elements  138  will refer herein to the maximum outer diameter of individual abrasive elements of the one or more abrasive elements  138 . In some embodiments, the one or more abrasive elements  138  are about 2 mm in size (maximum outer diameter). In some embodiments, the size of the one or more abrasive elements  138  is in a range of about 1.5 mm to about 2.5 mm, or about 1.0 mm to about 3.0 mm, or about 0.5 mm to about 4.0 mm, without limitation. Again, in a single embodiment, one or more of the abrasive elements  138  can have a different size in comparison to the other abrasive elements  138 . In some embodiments, the two outermost abrasive elements are about 1.5 mm in diameter and the inner abrasive elements are about 2.0 mm in diameter. 
     In the depicted embodiment, the one or more abrasive elements  138 , individually, are oblong in shape. A variety of different shapes can be used for the one or more abrasive elements  138 . For example, in some embodiments the one or more abrasive elements  138  are individually shaped as spheres, discs, rods, cylinders, polyhedrons, cubes, prisms, and the like. In some embodiments, such as the depicted embodiment, all of the one or more abrasive elements  138  are the same shape. In particular embodiments, one or more of the abrasive elements  138  has a different shape than one or more of the other abrasive elements  138 . That is, two, three, or more differing shapes of individual abrasive elements  138  can be combined on the same drive shaft  136 . 
     In the depicted embodiment, adjacent abrasive elements of the one or more abrasive elements  138  are spaced apart from each other. For example, in the depicted embodiment the two distal-most individual abrasive elements are spaced apart from each other by a distance ‘X’. In some embodiments, the spacing between adjacent abrasive elements is consistent between all of the one or more abrasive elements  138 . Alternatively, in some embodiments the spacing between some adjacent pairs of abrasive elements differs from the spacing between other adjacent pairs of abrasive elements. 
     In some embodiments, the spacing distance X in ratio to the maximum diameter of the abrasive elements  138  is about 1:1. That is, the spacing distance X is about equal to the maximum diameter. The spacing distance X can be selected to provide a desired degree of flexibility of the portion of the drive shaft  136  to which the one or more abrasive elements  138  are attached. In some embodiments, the ratio is about 1.5:1 (i.e., X is about 1.5 times longer than the maximum diameter). In some embodiments, the ratio is in a range of about 0.2:1 to about 0.4:1, or about 0.4:1 to about 0.6:1, or about 0.6:1 to about 0.8:1, or about 0.8:1 to about 1:1, or about 1:1 to about 1.2:1, or about 1.2:1 to about 1.4:1, or about 1.4:1 to about 1.6:1, or about 1.6:1 to about 1.8:1, or about 1.8:1 to about 2.0:1, or about 2.0:1 to about 2.2:1, or about 2.2:1 to about 2.4:1, or about 2.4:1 to about 3.0:1, or about 3.0:1 to about 4.0:1, and anywhere between or beyond those ranges. 
     In the depicted embodiment, the center of mass of each one of the one or more abrasive elements  138  is offset from the longitudinal axis of the drive shaft  136  along a same radial angle. Said another way, the centers of mass of all of the one or more abrasive elements  138  are coplanar with the longitudinal axis of the drive shaft  136 . If the size of each of the one or more abrasive elements  138  is equal, the centers of mass of the one or more abrasive elements  138  would be collinear on a line that is parallel to the longitudinal axis of the drive shaft  136 . 
     Referring to  FIG.  11   , according to some embodiments of the rotational atherectomy devices provided herein, one or more abrasive elements  144  are arranged at differing radial angles in relation to the drive shaft  136  as depicted here. Further, the draft shaft  136  is shown as in an unwinding state, as unwinding may optionally occur during rotation of the drive shaft  136  in some embodiments. In such a case, a path defined by the centers of mass of the one or more abrasive elements  144  spirals along the drive shaft  136  around the central longitudinal axis of the drive shaft  136 . In some cases (e.g., when the diameters of the one or more abrasive elements  144  are equal and the adjacent abrasive elements are all equally spaced), the centers of mass of the one or more abrasive elements  144  define a helical path along/around the drive shaft  136 . It has been found that such arrangements can provide a desirably-shaped orbital rotation of the one or more abrasive elements  144 . It should be noted that, in some embodiments, a controller assembly (e.g., controller assembly  240 ) is configured to control rotation and current input such that the drive shaft  136  is prevented from unwinding during rotation of the drive shaft  136 . 
     It should be understood that any of the structural features described in the context of one embodiment of the rotational atherectomy devices provided herein can be combined with any of the structural features described in the context of one or more other embodiments of the rotational atherectomy devices provided herein. For example, the size, spacing, and/or shape features (and any other characteristics) of the one or more abrasive elements  138  described in the context of  FIG.  1    can be incorporated in any desired combination with the spiral arrangement of the one or more abrasive elements  144 . 
     In some embodiments, the drive shaft assembly  130  includes at least four abrasive elements  144  attached to a distal end portion of the drive shaft  136  and each has a center of mass offset from the longitudinal axis of the drive shaft  136 . A spiral path defined by connecting the centers of mass of the at least four abrasive elements  144  spirals around the longitudinal axis of the drive shaft  136 . An overall radial angle of the spiral path is defined by a radial angle between a distal-most abrasive element of the at least four abrasive elements  144  and a proximal-most abrasive element of the at least four abrasive elements  144 . In some embodiments, the overall radial angle of the spiral path of the at least four abrasive elements  144  is always less than  180  degrees along any 10 cm length of the distal end portion of the drive shaft  136 . In some embodiments, the overall radial angle of the spiral path of the at least four abrasive elements  144  is always less than 170 degrees, or less than 160 degrees, or less than 150 degrees, or less than 140 degrees, or less than 130 degrees, or less than 120 degrees, or less than 110 degrees, or less than 100 degrees, or less than 90 degrees along any 10 cm length of the distal end portion of the drive shaft  136 . 
     In some embodiments, such as the depicted embodiment, the drive shaft assembly  130  includes a concentric abrasive tip member  141 . The concentric abrasive tip member  141  can be affixed to, and extending distally from, a distal-most end of the drive shaft  136 . In some embodiments that include the concentric abrasive tip member  141 , no distal stability element is included  140 . In particular embodiments (such as the depicted embodiment), the concentric abrasive tip member  141  and the distal stability element are both included  140 . 
     In some embodiments the concentric abrasive tip member  141  may be made of metallic materials such as stainless steel, tungsten, molybdenum, iridium, cobalt, cadmium, and the like, and alloys thereof. The concentric abrasive tip member  141  has a fixed outer diameter. That is, the concentric abrasive tip member  141  is not an expandable member in the depicted embodiment. The concentric abrasive tip member  141  may be mounted to the filars of the drive shaft  136  using a biocompatible adhesive, by welding, by press fitting, and the like, and by combinations thereof. Alternatively, the concentric abrasive tip member  141  can be integrally formed as a unitary structure with the filars of the drive shaft  136  (e.g., using filars of a different size or density, using filars that are double-wound to provide multiple filar layers, or the like). 
     In some embodiments, the concentric abrasive tip member  141  has an abrasive coating on its exterior surface. In particular embodiments, the concentric abrasive tip member  141  includes an abrasive material along an exterior circumferential surface, or on a distal end face/surface, or both. For example, in some embodiments a diamond coating (or other suitable type of abrasive coating) is disposed on the outer surface of the concentric abrasive tip member  141 . In some cases, such an abrasive surface on the concentric abrasive tip member  141  can help facilitate the passage of the concentric abrasive tip member  141  through vessel restrictions (such as calcified areas of a blood vessel). 
     In some embodiments, the concentric abrasive tip member  141  has an exterior surface that is smoother and different from an abrasive exterior surface of the one or more abrasive elements  138 . That may be the case whether or not the concentric abrasive tip member  141  have an abrasive coating on its exterior surface. In some embodiments, the abrasive coating on the exterior surface of the concentric abrasive tip member  141  is rougher than the abrasive surfaces on the one or more abrasive elements  138 . 
     The maximum outer diameter of the concentric abrasive tip member  141  may be smaller than, equal to, or larger than the outer diameter of the adjacent portion of the drive shaft  136 . The maximum outer diameter of the concentric abrasive tip member  141  may be smaller than, equal to, or larger than the maximum outer diameter of each of the one or more abrasive elements  144   a - e . The lateral width of the concentric abrasive tip member  141  (e.g., measured parallel to the longitudinal axis of the drive shaft  136 ) may be smaller than, equal to, or larger than the maximum lateral width of each of the one or more abrasive elements  144   a - e . 
     The concentric abrasive tip member  141  defines a central opening that is coaxial with the lumen defined by the drive shaft  136 . Accordingly, a guidewire (e.g., the guidewire  134  of  FIG.  1   ) can extend through the concentric abrasive tip member  141 . In some embodiments, the concentric abrasive tip member  141  is shaped as a toroid. In particular embodiments, the concentric abrasive tip member  141  is shaped as a hollow cylinder. In certain embodiments, the outer surface of the concentric abrasive tip member  141  defines one or more grooves, teeth, edges, and the like, and combinations thereof. 
     Next, as depicted by  FIGS.  12 - 14   , the rotation and translational motions of the drive shaft  136  (and the one or more abrasive elements  138 ) can be commenced to perform ablation of the lesion  14 . 
     In some implementations, prior to the ablation of the lesion  14  by the one or more abrasive elements  138 , an inflatable member can be used as an angioplasty balloon to treat the lesion  14 . That is, an inflatable member (on the sheath  132 , for example) can be positioned within the lesion  14  and then inflated to compress the lesion  14  against the inner wall  12  of the vessel  10 . Thereafter, the rotational atherectomy procedure can be performed. In some implementations, such an inflatable member can be used as an angioplasty balloon after the rotational atherectomy procedure is performed. In some implementations, additionally or alternatively, a stent can be placed at lesion  14  using an inflatable member on the sheath  132  (or another balloon member associated with the drive shaft assembly  130 ) after the rotational atherectomy procedure is performed. 
     The guidewire  134  may remain extending from the distal end of the drive shaft  136  during the atherectomy procedure as shown. For example, as depicted by  FIGS.  12 - 14   , the guidewire  134  extends through the lumen of the drive shaft  136  and further extends distally of the distal end of the distal extension portion  142  during the rotation and translational motions of the drive shaft  136  (refer, for example, to  FIGS.  12 - 14   ). In some alternative implementations, the guidewire  134  is withdrawn completely out of the lumen of the drive shaft  136  prior to during the rotation and translational motions of the drive shaft  136  for abrading the lesion  14 . In other implementations, the guidewire is withdrawn only partially. That is, in some implementations a portion of the guidewire remains within the lumen of the drive shaft  136  during rotation of the drive shaft  136 , but remains only in a proximal portion that is not subject to the significant orbital path in the area of the one or more abrasive elements  138  (e.g., remains within the portion of the drive shaft  136  that remains in the sheath  132 ). 
     To perform the atherectomy procedure, the drive shaft  136  is rotated at a high rate of rotation (e.g., 20,000-160,000 rpm) such that the eccentric one or more abrasive elements  138  revolve in an orbital path about an axis of rotation and thereby contacts and removes portions of the lesion  14 . 
     Still referring to  FIGS.  12 - 14   , the rotational atherectomy system  100  is depicted during the high-speed rotation of the drive shaft  136 . The centrifugal force acting on the eccentrically weighted one or more abrasive elements  138  causes the one or more abrasive elements  138  to orbit in an orbital path  131   a  around the axis of rotation  135 . In some implementations, the orbital path can be somewhat similar to the orbital motion of a “jump rope.” As shown, some portions of the drive shaft  136  (e.g., a portion that is just distal of the sheath  132  and another portion that is distal of the distal stability element  140 ) can remain in general alignment with the axis of rotation  135 , but the particular portion of the drive shaft  136  adjacent to the one or more abrasive elements  138  is not aligned with the axis of rotation  135  (and instead orbits around the axis  135 ). As such, in some implementations, the axis of rotation  135  may be aligned with the longitudinal axis of a proximal part of the drive shaft  136  (e.g., a part within the distal end of the sheath  132 ) and with the longitudinal axis of the distal extension portion  142  of the drive shaft  136 . 
     In some implementations, as the one or more abrasive elements  138  rotates, the clinician operator slowly advances the carriage assembly  204  distally (and, optionally, reciprocates both distally and proximally) in a longitudinal translation direction so that the abrasive surface of the one or more abrasive elements  138  scrapes against additional portions of the occluding lesion  14  to reduce the size of the occlusion, and to thereby improve the blood flow through the vessel  10 . This combination of rotational and translational motion of the one or more abrasive elements  138  is depicted by the sequence of  FIGS.  12 - 14   . 
     In some embodiments, the sheath  132  may define one or more lumens (e.g., the same lumen as, or another lumen than, the lumen in which the drive shaft  136  is located) that can be used for aspiration (e.g., of abraded particles of the lesion  14 ). In some cases, such lumens can be additionally or alternatively used to deliver perfusion and/or therapeutic substances to the location of the lesion  14 , or to prevent backflow of blood from vessel  10  into sheath  132 . 
     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. For example, design features of the embodiments described herein can be combined with other design features of other embodiments described herein. Accordingly, other embodiments are within the scope of the following claims.