Patent Publication Number: US-2022218386-A1

Title: Atherectomy devices and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/727,518 filed on Dec. 26, 2019, which is a continuation of U.S. application Ser. No. 16/192,431 filed on Nov. 15, 2018 (now U.S. Pat. No. 10,517,634), which is a continuation of U.S. application Ser. No. 16/168,087 filed Oct. 23, 2018 (now U.S. Pat. No. 10,335,187), which is a continuation of U.S. application Ser. No. 15/440,402 filed Feb. 23, 2017 (now U.S. Pat. No. 10,441,312). The entire contents of these related applications are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     This document relates to rotational atherectomy devices and systems for removing or reducing 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 rotational atherectomy systems described herein can remove or reduce stenotic lesions in blood vessels by rotating one or more abrasive elements to abrade and breakdown the lesion. Some embodiments can abrade stenotic lesions in blood vessels by rotating the abrasive element(s) according to a stable and predictable orbiting profile. In some embodiments, the abrasive element(s) are attached to a distal portion of an elongate flexible drive shaft that extends from a handle assembly. In particular embodiments, a rotational atherectomy device comprises an elongate flexible drive shaft with multiple eccentric abrasive elements that are attached to the drive shaft, and one or more weighted stability elements are attached to the drive shaft such that at least one stability element is distal of the abrasive element. Optionally, the stability elements have a center of mass that is axially aligned with a central longitudinal axis of the drive shaft while the eccentric abrasive element(s) has a center of mass that is axially offset from central longitudinal axis of the drive shaft. 
     In some embodiments, multiple abrasive elements are coupled to the drive shaft and are offset from each other around the drive shaft such that the centers of the abrasive elements are disposed at differing radial angles from the drive shaft in relation to each other. For example, in some embodiments a path defined by the centers of mass of the abrasive elements defines a spiral around a length of the central longitudinal axis of the drive shaft. A flexible polymer coating may surround at least a portion of the drive shaft, including the stability element(s) in some embodiments. Also, in some optional embodiments, a distal extension portion of the drive shaft may extend distally beyond the distal-most stability element. 
     In one aspect, this disclosure is directed to a rotational atherectomy device for removing stenotic lesion material from a blood vessel of a patient. In some embodiments, the rotational atherectomy device includes: (i) an elongate flexible drive shaft comprising a torque-transmitting coil and defining a longitudinal axis, the drive shaft being configured to rotate about the longitudinal axis; (ii) first and second abrasive elements attached to a distal end portion of the drive shaft and each having a center of mass offset from the longitudinal axis, the center of mass of the first abrasive element being offset from the longitudinal axis at a first radial angle, the center of mass of the second abrasive element being offset from the longitudinal axis at a second radial angle that differs from the first radial angle; and (iii) a distal stability element fixedly mounted to the drive shaft and having a center of mass aligned with the longitudinal axis, the distal stability element being distally spaced apart from the first and second abrasive elements. 
     Such a rotational atherectomy device may optionally include one or more of the following features. The device may also include a third abrasive element attached to the distal end portion of the drive shaft. The center of mass of the third abrasive element may be offset from the longitudinal axis along a third radial angle that differs from the first radial angle and the second radial angle. The second radial angle may differ from the first radial angle by at least 15 degrees. The third radial angle may differ from the first radial angle and the second radial angle by at least 15 degrees. The distal stability element may comprise a metal cylinder surrounding the torque-transmitting coil of the drive shaft and having a maximum diameter smaller than the first and second abrasive elements, and wherein the distal stability element has an abrasive outer surface. The device may also include an array of abrasive elements including the first and second abrasive elements and additional abrasive elements attached to the distal end portion of the drive shaft. In some embodiments, a proximal-most one of the array of abrasive elements and a distal-most one of the array of abrasives element are each smaller than intermediate ones of the array of abrasive elements. A path defined by the centers of mass of the array of abrasive elements may define at least a portion of a helical path around the longitudinal axis. The device may also include a flexible polymer coating along the drive shaft such that the coating surrounds an outer diameter of at least a portion of drive shaft. 
     In some embodiments, the rotational atherectomy device also includes: (iv) an actuator handle assembly configured to drive rotation of the drive shaft about the longitudinal axis, the actuator handle assembly comprising a carriage assembly that is movable in relation to other portions of the actuator handle assembly to translate the drive shaft along the longitudinal axis; and (v) a sheath extending from the actuator handle assembly, the drive shaft slidably disposed within a lumen defined by the sheath. 
     In another aspect, this disclosure is directed to a rotational atherectomy device for removing stenotic lesion material from a blood vessel of a patient. In some embodiments, the rotational atherectomy device includes: (a) an elongate flexible drive shaft comprising a torque-transmitting coil and defining a longitudinal axis, the drive shaft being configured to rotate about the longitudinal axis; (b) a helical array of abrasive elements attached to a distal end portion of the drive shaft, each of the abrasive elements having a center of mass that is offset from the longitudinal axis, the centers of mass of the abrasive elements being noncollinear; and (c) a distal stability element affixed to the drive shaft and having a center of mass aligned with the longitudinal axis, the distal stability element distally spaced apart from the plurality of abrasive elements. 
     Such a rotational atherectomy device may optionally include one or more of the following features. The device may also include a flexible polymer coating along the drive shaft such that the coating surrounds an outer diameter of at least a portion of drive shaft. The drive shaft may include a distal-most extension portion that extends distally of the distal stability element for a distal extension distance. The drive shaft may have a central lumen configured to receive a guidewire extending along the longitudinal axis. The distal stability element may comprise a metal cylinder surrounding the torque-transmitting coil, and wherein the metal cylinder has an abrasive outer surface. The plurality of abrasive elements may be spaced apart from each other by at least 50% of an outer diameter of a largest one of the abrasive elements. A proximal-most one of the abrasive elements and a distal-most one of the abrasives element may each be smaller than intermediate ones of the abrasive elements. A path defined by the centers of mass of sequential abrasive elements of plurality the abrasive elements may spiral around the longitudinal axis. The plurality of abrasive elements may include at least five abrasive elements. 
     In another aspect, this disclosure is directed to a system for performing rotational atherectomy to remove stenotic lesion material from a blood vessel of a patient. In some embodiments, the system includes: 1) an elongate flexible drive shaft comprising a torque-transmitting coil and defining a longitudinal axis, the drive shaft being configured to rotate about the longitudinal axis; 2) one or more abrasive elements attached to a distal end portion of the drive shaft, each of the abrasive elements having a center of mass that is offset from the longitudinal axis; 3) a distal stability element fixed to the drive shaft and having a center of mass aligned with the longitudinal axis, the distal stability element distally spaced apart from the plurality of abrasive elements; 4) an actuator handle assembly configured to drive rotation of the drive shaft about the longitudinal axis, the actuator handle assembly comprising a carriage assembly that is movable in relation to other portions of the actuator handle assembly to translate the drive shaft along the longitudinal axis; 6) a sheath extending from the actuator handle assembly, the drive shaft slidably disposed within a lumen defined by the sheath; and 7) a controller operably coupleable to the actuator handle assembly, the controller configured to provide output to the actuator handle assembly that causes the actuator handle assembly to drive the rotation of the drive shaft about the longitudinal axis. The controller can include a user interface with a plurality of selectable inputs corresponding to a plurality of vessel sizes. The controller may be configured to provide a respective output to the actuator handle assembly that differs for each of the vessel sizes. 
     Such a system for performing rotational atherectomy to remove stenotic lesion material from a blood vessel of a patient may optionally include one or more of the following features. A center of mass of a first one of the abrasive elements may be transversely offset from the longitudinal axis along a first angle. A center of mass of a second one of the abrasive elements may be transversely offset from the longitudinal axis along a second angle that differs from the first angle by at least 15 degrees. The system may also include a flexible polymer coating along the drive shaft such that the coating surrounds an outer diameter of at least a portion of drive shaft. In some embodiments, the distal stability element has an abrasive outer surface. 
     In another aspect, this disclosure is directed to a method for performing rotational atherectomy to remove stenotic lesion material from a blood vessel of a patient. In some embodiments, the method includes: delivering a rotational atherectomy device into the blood vessel and rotating the drive shaft about the longitudinal axis such that the abrasive elements orbit around the longitudinal axis. In some embodiments, the rotational atherectomy device includes: (a) an elongate flexible drive shaft comprising a torque-transmitting coil and defining a longitudinal axis, the drive shaft being configured to rotate about the longitudinal axis; (b) a helical array of abrasive elements attached to a distal end portion of the drive shaft, each of the abrasive elements having a center of mass that is offset from the longitudinal axis, the centers of mass of the abrasive elements arranged along a path that spirals around the longitudinal axis; and (c) a distal stability element affixed to the drive shaft and having a center of mass aligned with the longitudinal axis, the distal stability element distally spaced apart from the plurality of abrasive elements. 
     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 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 devices and systems provided herein include a handle assembly with a carriage that is manually translatable during rotation of the drive shaft, resulting in longitudinal translation of the rotating abrasive element in relation to a target lesion. In particular embodiments, a valve (or other connector) is mounted on the carriage and operable to control a supply of compressed gas (or other power source) to a carriage-mounted turbine member. The turbine member rotationally drives the drive shaft of the atherectomy device. Hence, in some embodiments the valve for actuating the rotational operation of the drive shaft is conveniently located on the translatable carriage of the handle assembly. Alternatively, in some embodiments an electric motor is used to drive rotations of the drive shaft. 
     Third, some embodiments of the rotational atherectomy devices and systems operate with a stable and predictable rotary motion profile for enhanced atherectomy performance. That is, when the device is being rotated in operation, the eccentric abrasive element(s) follows a predefined, consistent orbital path (offset from an axis of rotation of the device) while the stability element(s) and other portions of the device remain on or near to the axis of rotation for the drive shaft in a stable manner. This predictable orbital motion profile can be attained by the use of design features including, but not limited to, stability element(s) that have centers of mass that are coaxial with the longitudinal axis of the drive shaft, a polymeric coating on at least a portion of the drive shaft, a distal-most drive shaft extension portion, and the like. Some embodiments of the rotational atherectomy devices and systems provided herein may include one or more of such design features. 
     Fourth, some embodiments of the rotational atherectomy devices and systems provided herein can be used to treat large-diameter vessels (including renal and iliac arteries having an internal diameter that is multiple time greater than the outer diameter of the abrasive element) while requiring only a small introducer sheath size. In other words, in some embodiments the rotating eccentric abrasive element(s) traces an orbital path that is substantially larger than the outer diameter of the rotational atherectomy device in the non-rotating state. This feature improves the ability of the rotational atherectomy devices provided herein to treat very large vessels while still fitting within a small introducer size. In some embodiments, this feature can be at least partially attained by using a helical array of abrasive elements that has a high eccentric mass (e.g., the centers of mass of the abrasive elements are significantly offset from the central longitudinal axis of the drive shaft). Further, in some embodiments this feature can be at least partially attained by using multiple abrasive elements that are offset from each other around the drive shaft such that the centers of the abrasive elements are not coaxial with each other. 
     Fifth, in some embodiments the rotational atherectomy devices include a distal stability element that has an abrasive outer surface. In some cases, while the rotational atherectomy device is being advanced within the vasculature of a patient, the distal end of the rotational atherectomy device may encounter lesions that occlude or substantially occlude the vessel. In such a case, the abrasive outer surface on the distal stability element may help facilitate passage of the distal stability element through lesions that occlude or substantially occlude the vessel. In some such cases the drive shaft may be used to rotate the distal stability element to help facilitate boring of the distal stability element through such lesions in a drill-like fashion. 
     Sixth, in some embodiments rotational atherectomy systems described herein include user controls that are convenient and straight-forward to operate. In one such example, the user controls can include selectable elements that correspond to the diametric size of the vessel to be treated. When the clinician-user selects the particular vessel size, the system will determine an appropriate rpm of the drive shaft to obtain the desired orbit of the abrasive element(s) for the particular vessel size. Hence, in such a case the clinician-user conveniently does not need to explicitly select or control the rpm of the drive shaft. In another 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,” “medium,” or “high” speeds. 
     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  shows a guidewire being advanced through a lesion in a blood vessel. 
         FIG. 3  shows an example rotational atherectomy device being advanced over the guidewire of  FIG. 2  and into region of the lesion. 
         FIG. 4  shows the example rotational atherectomy device of  FIG. 3  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. 5  shows the rotational atherectomy device of  FIG. 3  with the abrasive element being rotated at a second longitudinal position that is distal of the first longitudinal position. 
         FIG. 6  shows the rotational atherectomy device of  FIG. 3  with the abrasive element being rotated at a third longitudinal position that is distal of the second longitudinal position. 
         FIG. 7  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. 
         FIG. 8  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. The individual portions of the multi-portion abrasive element are offset from each other around the drive shaft such that the centers of mass of the abrasive element portions define a spiral path around the drive shaft axis. 
         FIG. 9  is a transverse cross-sectional view of the rotational atherectomy device of  FIG. 8  taken along the cutting-plane line  9 - 9 . 
         FIG. 10  is a transverse cross-sectional view of the rotational atherectomy device of  FIG. 8  taken along the cutting-plane line  10 - 10 . 
         FIG. 11  is a transverse cross-sectional view of the rotational atherectomy device of  FIG. 8  taken along the cutting-plane line  11 - 11 . 
         FIG. 12  is a transverse cross-sectional view of the rotational atherectomy device of  FIG. 8  taken along the cutting-plane line  12 - 12 . 
         FIG. 13  is a transverse cross-sectional view of the rotational atherectomy device of  FIG. 8  taken along the cutting-plane line  13 - 13 . 
         FIG. 14  shows an example user control unit of a rotational atherectomy system that is being operated by a clinician-user to perform a rotational atherectomy procedure below the knee of a patient. 
         FIG. 15  shows the example user control unit of  FIG. 14  being operated to perform a rotational atherectomy procedure above the knee of a patient. 
         FIG. 16  shows an example user control unit with another type of user interface. 
     
    
    
     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 , an actuator handle assembly  110 , an elongate flexible drive shaft assembly  130 , and a controller  150 . The drive shaft assembly  130  extends distally from the handle assembly  110 . The controller  150  is connected to the handle assembly  110  via a cable assembly  160 . The handle assembly  110  and controller  150  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  110 . 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&#39;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  (as described below, for example, in connection with  FIGS. 4-6 ). 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 (as described below, for example, in connection with  FIGS. 4-6 ). 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. 7-8 ). 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 , the rotational atherectomy system  100  also includes the actuator handle assembly  110 . The actuator handle assembly  110  includes a housing  112  and a carriage assembly  114 . The carriage assembly  114  is slidably translatable along the longitudinal axis of the handle assembly  110  as indicated by the arrow  115 . For example, in some embodiments the carriage assembly  114  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  114  is translated in relation to the housing  112 , the drive shaft  136  translates in relation to the sheath  132  in a corresponding manner. 
     In the depicted embodiment, the carriage assembly  114  includes a valve actuator  116 . In some embodiments, an electric motor for driving rotations of the drive shaft  136  is coupled to the carriage assembly  114  such that the valve actuator  116  is an electrical switch instead. In the depicted embodiment, the valve actuator  116  is a button that can be depressed to actuate a compressed gas control valve (on/off; defaulting to off) mounted to the carriage assembly  114 . While the valve actuator  116  is depressed, a compressed gas (e.g., air, nitrogen, etc.) is supplied through the valve to a turbine member that is rotatably coupled to the carriage assembly  114  and fixedly coupled to the drive shaft  136 . Hence, an activation of the valve actuator  116  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  110  during a rotational atherectomy procedure, a clinician can grasp the carriage assembly  114  and depress the valve actuator  116  with the same hand. The clinician can move (translate) the carriage assembly  114  distally and proximally by hand (e.g., back and forth in relation to the housing  112 ), while maintaining the valve actuator  116  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. 
     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&#39;s preference, type of treatment being delivered, and other such factors. 
     In the depicted embodiment, the handle assembly  110  also includes a guidewire detention mechanism  118 . The guidewire detention mechanism  118  can be selectively actuated (e.g., rotated) to releasably clamp and maintain the guidewire  134  in a stationary position relative to the handle assembly  110  (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  110  are being advanced over the guidewire  134  to put the one or more abrasive elements  138  into a targeted position within a patient&#39;s vessel, the guidewire detention mechanism  118  will be unactuated so that the handle assembly  110  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  118  can be actuated to releasably detain/lock the guidewire  134  in relation to the handle assembly  110 . 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  114  is being manually translated. 
     Still referring to  FIG. 1 , the rotational atherectomy system  100  also includes the controller  150 . In the depicted embodiment, the controller  150  includes a user interface  152  that includes a plurality of selectable inputs  154  that correspond to a plurality of vessel sizes (diameters). To operate the rotational atherectomy system  100 , the user can select a particular one of the selectable inputs  154  that corresponds to the diameter of the vessel being treated. In response, the controller  150  will determine the appropriate gas pressure for rotating the drive shaft  136  in a vessel of the selected diameter (faster rpm for larger vessels and slower rpm for smaller vessel), and supply the gas at the appropriate pressure to the handle assembly  110 . 
     In some embodiments, the controller  150  is pole-mounted. The controller  150  can be used to control particular operations of the handle assembly  110  and the drive shaft assembly  130 . For example, the controller  150  can be used to compute, display, and adjust the rotational speed of the drive shaft  136 . 
     In some embodiments, the controller  150  can include electronic controls that are in electrical communication with a turbine RPM sensor located on the carriage assembly  114 . The controller  150  can convert the signal(s) from the sensor into a corresponding RPM quantity and display the RPM on the user interface  152 . If a speed adjustment is desired, the clinician can increase or decrease the rotational speed of the drive shaft  136 . In result, a flow or pressure of compressed gas supplied from the controller  150  to the handle assembly  110  (via the cable assembly  160 ) will be modulated. The modulation of the flow or pressure of the compressed gas will result in a corresponding modulation of the RPM of the turbine member and of the drive shaft  136 . 
     In some embodiments, the controller  150  includes one or more interlock features that can enhance the functionality of the rotational atherectomy system  100 . In one such example, if the controller  150  does not detect any electrical signal (or a proper signal) from the turbine RPM sensor, the controller  150  can discontinue the supply of compressed gas. In another example, if a pressure of a flush liquid supplied to the sheath  132  is below a threshold pressure value, the controller  150  can discontinue the supply of compressed gas. 
     Referring also to  FIGS. 2-6 , the rotational atherectomy system  100  can be used to treat a vessel  10  having a stenotic lesion  14  along an inner wall  12  of the vessel  10 . The rotational atherectomy system  100  is used to fully or partially remove the stenotic lesion  14 , thereby removing or reducing the blockage within the vessel  10  caused by the stenotic lesion  14 . By performing such a treatment, the blood flow through the vessel  10  may be thereafter increased or otherwise improved. The vessel  10  and lesion  14  are shown in longitudinal cross-sectional views to enable visualization of the rotational atherectomy system  100 . 
     Briefly, in some implementations the following activities may occur to achieve the deployed arrangement shown in  FIGS. 2-6 . In some embodiments, an introducer sheath (not shown) can be percutaneously advanced into the vasculature of the patient. The guidewire  134  can then be inserted through a lumen of the introducer sheath and navigated within the patient&#39;s vasculature to a target location (e.g., the location of the lesion  14 ). Techniques such as x-ray fluoroscopy or ultrasonic imaging may be used to provide visualization of the guidewire  134  and other atherectomy system components during placement. In some embodiments, no introducer sheath is used and the guidewire  134  is inserted without assistance from a sheath. The resulting arrangement is depicted in  FIG. 2 . 
     Next, as depicted in  FIG. 3 , portions of the rotational atherectomy system  100  can be inserted over the guidewire  134 . For example, an opening to the lumen of the drive shaft  136  at the distal free end of the drive shaft  136  (e.g., at the distal end of the optional distal drive shaft extension portion  142 ) can be placed onto the guidewire  134 , and then the drive shaft assembly  130  and handle assembly  110  can be gradually advanced over the guidewire  134  to the position in relation to the lesion  14  as shown. In some cases, the drive shaft  136  is disposed fully within the lumen of the sheath  132  during the advancing. In some cases, a distal end portion of the drive shaft  136  extends from the distal end opening  143  of the sheath  132  during the advancing. Eventually, after enough advancing, the proximal end of the guidewire  134  will extend proximally from the handle assembly  110  (via the access port  120  defined by the handle housing  112 ). 
     In some cases (such as in the depicted example), the lesion  14  may be so large (i.e., so extensively occluding the vessel  10 ) that it is difficult or impossible to push the distal stability element  140  through the lesion  14 . In some such cases, an abrasive outer surface on the distal stability element  140  can be used to help facilitate passage of the distal stability element  140  into or through the lesion  14 . In some such cases, the drive shaft  136  can be rotated to further help facilitate the distal stability element  140  to bore into/through the lesion  14 . 
     Next, as depicted by  FIGS. 4-6 , 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. 4-6 , 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. 4-6 ). 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. 4-6 , 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 around the axis of rotation  139 . 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  139 , 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  139  (and instead orbits around the axis  139 ). As such, in some implementations, the axis of rotation  139  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  114  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. 4-6 . 
     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 . 
     Referring to  FIG. 7 , 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 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. 8 , 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 . 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 . 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 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 and/or shape features of the one or more abrasive elements  138  can be incorporated in any desired combination with the spiral arrangement of the one or more abrasive elements  144 . 
     Referring also to  FIGS. 9-13 , the differing radial angles of the individual abrasive elements  144   a ,  144   b ,  144   c ,  144   d , and  144   e  can be further visualized. To avoid confusion, each figure of  FIGS. 9-13  illustrates only the closest one of the individual abrasive elements  144   a ,  144   b ,  144   c ,  144   d , and  144   e  (i.e., closest in terms of the corresponding cutting-plane as shown in  FIG. 8 ). For example, in  FIG. 10 , abrasive element  144   b  is shown, but abrasive element  144   a  is not shown (so that the radial orientation of the abrasive element  144   b  is clearly depicted). 
     It can be seen in  FIGS. 9-13  that the centers of mass of abrasive elements  144   a ,  144   b ,  144   c ,  144   d , and  144   e  are at differing radial angles in relation to the drive shaft  136 . Hence, it can be said that the abrasive elements  144   a ,  144   b ,  144   c ,  144   d , and  144   e  are disposed at differing radial angles in relation to the drive shaft  136 . 
     In the depicted embodiment, the radial angles of the abrasive elements  144   a ,  144   b ,  144   c ,  144   d , and  144   e  differ from each other by a consistent 37.5 degrees (approximately) in comparison to the adjacent abrasive element(s). For example, the center of mass of abrasive element  144   b  is disposed at a radial angle B that is about 37.5 degrees different than the angle at which the center of mass of abrasive element  144   a  is disposed, and about 37.5 degrees different than the angle C at which the center of mass of abrasive element  144   c  is disposed. Similarly, the center of mass of abrasive element  144   c  is disposed at a radial angle C that is about 37.5 degrees different than the angle B at which the center of mass of abrasive element  144   b  is disposed, and about 37.5 degrees different than the angle D at which the center of mass of abrasive element  144   d  is disposed. The same type of relative relationships can be said about abrasive element  144   d.    
     While the depicted embodiment has a relative radial offset of 37.5 degrees (approximately) in comparison to the adjacent abrasive element(s), a variety of other relative radial offsets are envisioned. For example, in some embodiments the relative radial offsets of the adjacent abrasive elements is in a range of about 0 degrees to about 5 degrees, or about 5 degrees to about 10 degrees, or about 10 degrees to about 15 degrees, or about 15 degrees to about 20 degrees, or about 20 degrees to about 25 degrees, or about 25 degrees to about 30 degrees, or about 30 degrees to about 35 degrees, or about 10 degrees to about 30 degrees, or about 20 degrees to about 40 degrees, or about 20 degrees to about 50 degrees. 
     While in the depicted embodiment, the relative radial offsets of the abrasive elements  144   a ,  144   b ,  144   c ,  144   d , and  144   e  in comparison to the adjacent abrasive element(s) are consistent, in some embodiments some abrasive elements are radially offset to a greater or lesser extent than others. For example, while angles B, C, D, and E are all multiples of 37.5 degrees, in some embodiments one or more of the angles B, C, D, and/or E is not a multiple of the same angle as the others. 
     The direction of the spiral defined by the centers of mass of the abrasive elements  144   a ,  144   b ,  144   c ,  144   d , and  144   e  can be in either direction around the drive shaft  136 , and in either the same direction as the wind of the filars or in the opposing direction as the wind of the filars. 
     Referring to  FIG. 14 , the rotational atherectomy system  100  also includes the controller  150 . In the depicted embodiment, the controller  150  includes a user interface  152  that includes a plurality of selectable inputs  154  that correspond to a plurality of vessel sizes (diameters). Other types of user interfaces are also envisioned (e.g., refer to  FIG. 16 ). To operate the rotational atherectomy system  100 , the user can select a particular one of the selectable inputs  154  that corresponds to the diameter of the vessel being treated. In response, the controller  150  will determine the appropriate gas pressure for rotating the one or more abrasive elements  138  in a vessel of the selected diameter (faster rpm for larger vessels and slower rpm for smaller vessel), and supply the gas at the appropriate pressure to the handle assembly  110 . In some embodiments, the driver for rotation of the one or more abrasive elements  138  is an electrical motor rather than the pneumatic motor included in the depicted example. 
     In the depicted example, the vessel to be treated is in a leg  10  of a patient. In particular, the vessel is below a knee  12  (e.g., an tibial artery, without limitation). Such a vessel can tend to be relatively small in diameter. Therefore, in this illustrative example, the clinician user is inputting a vessel size of 4.0 mm. In response, the controller  150  will determine the appropriate gas pressure for rotating the one or more abrasive elements  138  in a 4.0 mm vessel. For example, that speed may be about 40,000 rpm. The corresponding gas pressure will be supplied to the handle assembly  110  via cable assembly  160  ( FIG. 1 ). 
     Referring to  FIG. 15 , in another example, the vessel to be treated is above the knee  12 . For example, without limitation, the vessel may be an iliac or femoral artery. Such a vessel will tend to be relatively large in diameter. Therefore, in this illustrative example, the clinician user is inputting a vessel size of 8.0 mm. In response, the controller  150  will determine the appropriate gas pressure for rotating the one or more abrasive elements  138  in an 8.0 mm vessel. For example, that speed may be about 80,000 rpm. The corresponding gas pressure will be supplied to the handle assembly  110  via cable assembly  160  ( FIG. 1 ). 
     Referring to  FIG. 16 , in some embodiments the rotational atherectomy systems described herein can include a controller  250  that has is configured with an example user interface  252 . The user interface  252  includes readily understandable and convenient-to-use selectable inputs  254  that correspond to the rotational speed at which the drive shaft will be driven by the controller  250 . 
     In this example, the user interface  252  is configured such that the user can simply select either “LOW,” “MED,” or “HIGH” speed via the selectable inputs  254 . Based on the user&#39;s selection of either “LOW,” “MED,” or “HIGH,” the controller  250  will provide a corresponding output for rotating the drive shaft at a corresponding rotational speed. It should be understood that the user interfaces  152  (e.g.,  FIGS. 14 and 15 ) and  252  are merely exemplary and non-limiting. That is, other types of user interface controls can also be suitably used, and are envisioned within the scope of this disclosure. 
     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.