HK1144544B - Rotational atherectomy device with counterweighting - Google Patents

Abstract

The present invention provides a rotational atherectomy device comprising a flexible, elongated, rotatable drive shaft with an abrasive component, the abrasive component including an enlarged diameter portion of the drive shaft or a solid abrasive crown connected to the drive shaft. The device further comprises counterweights mounted proximally and/or distally, spaced from the drive shaft and the abrasive component, wherein the center of mass of each counterweight is offset from the longitudinal axis of the drive shaft to promote orbital motion of the abrasive component. When the device is placed in an artery to remove stenotic lesions, the device rotates at a high speed (e.g., in the range of approximately 20,000 rpm to 200,000 rpm), and the orbital nature of the abrasive component causes the abrasive component to create an opening in the stenotic lesion that is larger than the resting outer diameter of the abrasive component.

Description

Atherectomy device with counterweight

Technical Field

The present invention relates to devices and methods for removing tissue from a body passageway, such as an atherosclerotic plaque from an artery, using a high speed rotational atherectomy (atherectomy) device.

Background

Numerous techniques and instruments have been developed to remove or repair tissue in arteries and body passageways similar to arteries. A common use of these techniques and instruments is to remove atherosclerotic plaque from a patient's artery. Atherosclerosis is characterized by the constant accumulation of fat (atheromas) in the intima (subcutaneous lining) of a patient's blood vessel. Generally, over time, initially a relatively soft deposit, the cholesterol-rich atherosclerotic material hardens into calcified atherosclerotic plaques. Such atheromatous plaques restrict the flow of blood and are therefore commonly referred to as stenotic lesions (stenoses) or stenoses (stenoses), while obstructive material is referred to as stenotic material. If left untreated, this stenosis can cause angina, hypertension, myocardial infarction, stroke, and the like.

Atherectomy has been a popular technique for removing those stenotic materials. This procedure is most often used to open the initial stages of calcified lesions in the coronary arteries. In most cases, atherectomy is not used alone, and is often followed by balloon angioplasty (balloon angioplasty procedure), which is often followed by implantation of an endovascular stent to help maintain patency of the opened vessel (patent). For non-calcified lesions, balloon angioplasty is often used alone to open the artery, and endovascular stents are often used to maintain patency of the opened vessel. However, studies have shown that in patients undergoing balloon angioplasty and arterial stenting, a significant proportion of patients experience restenosis-i.e., occlusion-of the stent, which is usually caused over time by excessive growth of scar tissue in the stent. In this case, atherectomy becomes the preferred procedure to remove excess scar tissue from the intravascular stent (balloon angioplasty is not very effective in the stent), thereby restoring vessel patency.

Several atherectomy devices have been developed for removing stenotic material from atherosclerotic plaques. One device, shown in us patent 4,990,124(Auth), has a flexible drive rod with an end coated with an abrasive material, such as diamond particles, concentrically shaped ellipsoidal burr (burr). The burr is highly rotated (typically, for example, between 150,000-190,000 rpm) as it advances through the stenosis. However, the burr obstructs blood flow when removing stenotic tissue. Once the burr is advanced through the stenosis, the artery is opened to a diameter comparable to or slightly larger than the maximum outer diameter of the burr. Typically, because the burr has a fixed resting diameter, more than one size of burr must be used to open the desired diameter opening in the artery. Then it is. The Auth equipment solution does not disclose that other variations in diameter that are variable or larger than the rest diameter of the burr can be covered at high rotational speeds.

U.S. Pat. No. 5,681,336 (element) provides an eccentric (eccentric) tissue-removing burr having abrasive particles held in place by a suitable binder material on an exterior surface portion thereof. However, this configuration has its limitations, as Clement explains at column 3, lines 53-55, that the rotational speed of the asymmetric burr is "slower than the speed of the high speed ablation device to balance heat or device imbalance". That is, given a solid burr of both size and volume, high burr rotation is not feasible during atherectomy procedures, such as between 20,000 and 200,000 rpm. In fact, a center of mass offset from the axis of rotation of the drive shaft results in a significant, undesirable centrifugal force that can place too much pressure on the arterial wall, generating a lot of heat and oversized particles. As in the Auth patent, the size of the burr is fixed and it may be necessary to use more than one size burr to open a desired diameter opening in the main lumen.

Disclosure of Invention

The present invention provides an atherectomy device having a flexible, elongated, rotatable drive shaft, the abrasive section of the drive shaft of the device comprising an enlarged diameter section of the drive shaft, or a solid abrasive crown (crown) that can be affixed to the drive shaft. The apparatus further includes counterweights (counterweights) mounted at either the proximal or distal ends of the drive rod and spaced from the abrasive elements, wherein the center of mass of each counterweight is offset from the longitudinal axis of the drive rod to facilitate orbital movement of the abrasive elements. When the device is placed in an artery to obliterate stenotic tissue and rotated at sufficiently high speeds (e.g., between 20,000 and 200,000 rpm), the orbital nature of the abrasive member causes the member to open an opening in the stenotic lesion that is significantly larger in diameter than the resting outer diameter of the abrasive member as it is rotated.

The invention aims to provide a high-speed rotational atherectomy device with an abrasive section which rotates at high speed and has a diameter larger than the rest diameter.

It is an object of the present invention to provide a high-speed rotational atherectomy device having concentric abrasive segments that rotate at high speed to a diameter greater than their resting diameter.

It is another object of the present invention to provide a high-speed rotational atherectomy device with an eccentric abrasive section having a diameter that is larger at high rotational speeds than its resting diameter.

It is another object of the present invention to provide a high-speed rotational atherectomy device with a drive shaft having two weights, one weight located at the proximal end of the abrasive section and the other weight located at the distal end of the abrasive section.

It is another object of the present invention to provide a high-speed rotational atherectomy device wherein the drive shaft is provided with at least one counterweight, the at least one counterweight being located at the proximal or distal end of the abrasive section.

The figures and the detailed description that follow illustrate these and other embodiments of the invention.

Drawings

The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of a non-flexible eccentric cutting head of the rotational atherectomy device of the present invention;

FIG. 2 is an enlarged partial perspective view of a flexible eccentric member of a prior art drive rod;

FIG. 3 is an enlarged, partial, longitudinal cross-sectional view of an eccentric portion of a prior art drive rod;

FIG. 4 is an enlarged partial, longitudinal cross-sectional view of a flexible, solid, eccentric burr mounted on a prior art drive rod;

FIG. 5A is a perspective view of a prior art eccentric abrading head or crown mounted on a drive rod;

FIG. 5B is a bottom view of a prior art eccentric abrading head or crown mounted on a drive rod;

FIG. 5C is a longitudinal cross-sectional view of a prior art eccentric abrading head or crown mounted on a drive rod;

FIG. 6 is a longitudinal cross-sectional view of one embodiment of the present invention;

FIG. 7A is a cross-sectional view of one embodiment of the present invention;

FIG. 7B is a cross-sectional view of one embodiment of the present invention;

FIG. 7C is a cross-sectional view of one embodiment of the present invention;

figure 8 is a cross-sectional view showing three different positions of the fast-rotating abrasive component of the eccentric atherectomy device of the present invention;

fig. 9 is a schematic view of the fast rotating abrasive component of fig. 8 in three different positions.

Detailed Description

With various modifications and substitutions as reasonable in the disclosure, the details of the disclosure are set forth herein by way of illustration and description. It should be noted, however, that the scope of the present invention is not limited by the particular embodiments of the present invention described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Figure 1 illustrates a typical atherectomy device invention. This device includes a handle portion 10, an extended flexible drive rod 20 having an abrading member 28, the abrading member 28 including an eccentric enlarged diameter member 28A, and an extension catheter 13 extending from the distal end of the handle portion 10. The drive rod 20 and its eccentric enlarged diameter member 28 are formed of a helically wound coil. The catheter 13 has a lumen in which the drive rod 20 is disposed for most of its length, except for the enlarged diameter section 28A and a small portion of the distal end of the enlarged diameter section 28. Drive shaft 20 also includes a lumen through which drive shaft 20 can be advanced and rotated via guidewire 15. A liquid supply line 17 may also be provided for injecting a cooling and lubricating solution (typically saline or other biologically suitable liquid) into the conduit 13.

The handle 10 may include a turbine (or similar rotational drive mechanism) for driving the high speed rotation of the drive rod 20. The handle 10 may be generally connected to a power source, such as compressed air delivered through a conduit 16. The fiber optic cable pair 23 may be used to monitor the rotational speed of the turbine and drive shaft 20 (details regarding such processing and related instrumentation are known in the art and described in, for example, U.S. issued patent 5,314,407 to Auth). The handle 10 may also include a control handle 11 for advancing and retracting a turbine and drive shaft 20 associated with the conduit 13 and handle.

Fig. 2 and 3 show details of the grinding member 28, including an eccentric enlarged diameter member 28A. The drive shaft 20 is formed of one or more helically wound coils 18 defining a guide wire lumen 19 and a cavity 25 within the enlarged diameter portion 28A. The cavity 25 is actually empty unless the guidewire 15 is passed through the cavity 25. Eccentric enlarged diameter portion 28A of abrasive member 28 is shown to include proximal end 30, intermediate end 35, and distal end 40 with tissue clearance surface 37 disposed thereon. Preferably, the diameter of the coil 31 of the proximal end portion 30 of the eccentric enlarged diameter member 28A increases continuously from the distal end, and thus is generally conically shaped. Preferably, the diameter of the coil 41 of the distal portion 40 increases continuously from the distal end, and thus generally forms a conical shape. The coil 36 of the intermediate section 35 is formed with a bulge in its outer surface in a gradually changing diameter manner, the shape of the outer surface providing a smooth transition between the proximal and distal conical portions of the enlarged diameter section 28A of the drive rod 20.

At least a portion of the abrasive member 28, shown as an eccentric enlarged diameter member 28A (preferably the intermediate portion 35), includes an outer surface 37 capable of clearing tissue. Preferably, the tissue removal surface includes a coating 37 of abrasive material 24 that forms the tissue removal portion of the drive rod 20. The abrasive material may be any suitable material, such as diamond dust, fused silica, titanium nitride, tungsten carbide, alumina, boron carbide, or other ceramic materials. Preferably, the abrasive material comprises diamond chips (or particles) secured directly to the coils of the drive rod 20 by a suitable adhesive 26-such securement may be achieved by known techniques, such as conventional electroplating or welding techniques (see U.S. Pat. No. 4,018,576). Alternatively, the external tissue-clearing surface may be only a portion of the coil that has been roughened to provide a suitable abrasive surface. In another variation, the outer surface may be etched or cut (e.g., with a laser) to provide a small, sharp cut surface. Other similar techniques may be used to provide a suitable tissue removal surface.

Shown in fig. 4 is another known abrasive component 28 showing an eccentric solid construction or at least partially hollow burr 28B. A solid or at least partially hollow burr 28B is attached to the drive rod 20 in a manner known in the art and includes a coating of abrasive material 24 secured to the surface by a suitable adhesive 26.

Figures 5A, 5B and 5C illustrate another known abrading component 28, including an eccentric abrading head or crown 28C as described in U.S. patent application No. 11/761,128 to Thatcher et al, the disclosures of which are incorporated herein by reference in their entirety. A lumen 23 is provided to crimp fit over the drive rod 20 and may include a hollow member 25 to assist in driving the center of mass away from or toward the axis of rotation of the drive rod 20. The abrasive member 28C includes a proximal portion 30, an intermediate portion 35, and a distal portion 40, the proximal portion 30 and the distal portion 40 being inclined away from the intermediate portion 35 and having a cylindrical shape.

One embodiment of the present invention includes an abrasive member 28, which abrasive member 28 may in turn comprise an eccentric enlarged section 28A of the drive shaft, or an eccentric solid crown or abrading head 28C or eccentric burr 28B mounted on the drive shaft, wherein the abrasive member 28 has a center of mass radially distributed from the axis of rotation of the drive shaft 20 to facilitate opening of the device at stenotic lesions with a diameter significantly larger than the outer diameter of the abrasive member 28. This can be accomplished by offsetting the geometric center of the grinding member 28, such as an eccentrically enlarged portion of the drive rod 20, or an eccentric solid grinding bit or crown 28C or burr 28B mounted on the drive rod 20, from the rotational axis of the drive rod 20. Alternatively, the center of mass of the abrasive elements 28 may be radially offset from the axis of rotation of the drive rod by different combinations of materials comprising abrasive elements 28, wherein at least one abrasive element 28 comprises a material of greater mass and density on one side than on the other side, which results in eccentricity (eccentricities) as described herein. As known to those skilled in the art, the eccentricity can be achieved by using different materials in the grinding member 28, such as offsetting the center of mass of the drive rod axis of rotation, and this method can be used for any embodiment of the grinding member 28, whether concentric, eccentric, solid burr, partially hollow crown or grinding bit, or enlarged member of the drive rod, or equivalent member.

Embodiments of the present invention may further include at least one weight positioned on and fixedly attached to the drive rod to facilitate the orbital movement of the eccentric abrading element. At least one such weight may be located at the proximal end of the abrasive member and another may be located at the distal end of the abrasive member.

In one embodiment, as shown in fig. 6, the grinding member 28 is shown as an eccentric enlarged diameter member 28A of the drive rod 20. The distal counterweight 100 is located at the distal end of the abrasive member 28, while the proximal counterweight 102 is located at the proximal end of the abrasive member. Alternative embodiments may include only a distal counterweight 100 that cooperates with the abrasive member 28, or only a proximal counterweight 102 that cooperates with the abrasive member 28.

As shown in FIG. 6, the weights 100, 102 are solid and eccentric burr cones, but the present invention includes numerous alternative embodiments.

For example, one or both of the proximal and distal counterweights 102, 100 may comprise an enlarged diameter section of the drive rod configured in a similar manner as the enlarged eccentric diameter abrasive section 28A. In this embodiment, the weights 100, 102 are hollow, enlarged coils of the drive rod 20 that use a mandrel (mandrel) during the winding process. In the case of only one weight, whether proximal weight 102 or distal weight 100, the weight is an enlarged eccentric diameter grinding section of drive rod 20, and the remaining weights may be concentric, i.e., having a center of mass collinear with the axis of rotation of the drive rod and comprising the enlarged diameter section, a solid crown or at least partially hollow crown of the drive rod, or eccentric and comprising a solid burr or at least partially hollow crown or grinding bit.

Alternatively, one or both of the proximal and distal counterweights 102, 100 may be solid, as shown in fig. 6, and connected to the coils of the drive rod 20 by means known to those skilled in the art. In other variations, the proximal and distal counterweights 102, 100 may also be at least partially hollow. In a further variation, one or both of the proximal and distal counterweights 102, 100 may comprise a different combination of materials, wherein one side of at least one of the counterweights 100, 102 comprises a material of greater mass or density than the other side, resulting in the noted eccentricity. Those skilled in the art will recognize the innovation of using different materials within the arrangements 100, 102 to achieve eccentricity, such as center of mass offset drive rod rotation axis, and that this approach can be used with any embodiment of the arrangements 100, 102, whether concentric, eccentric, solid burr, partially hollow crown or grinding bit, or enlarged section of the drive rod, or equivalent section.

In one embodiment, the overall mass of the proximal and distal counterweights 102, 100 as shown in fig. 6 is substantially equal, each counterweight 100, 102 being approximately one-half the overall mass of the abrasive component 28, wherein the proximal and distal counterweights 102, 100 are equidistant from the abrasive component 28, wherein the proximal and distal counterweights 102, 100 comprise a center of mass equidistant from the rotational axis of the drive rod 20, and wherein the center of mass of the proximal and distal counterweights 102, 100 is equidistant from the center of mass of the eccentric abrasive component 28. A shifting or equivalent mass distribution between the grinding member 28 and the counterweight for controlling the orbital diameter of rotation of the grinding member 28 during high speed rotation, as would be readily understood by one skilled in the art, is within the scope of the present invention.

Further, one or both of the weights (proximal and/or distal) 102, 100 may be concentric, i.e., spherical or ellipsoidal in shape or other concentric shape, with the center of mass of one or both of the weights (proximal and/or distal) 102, 100 being substantially located, e.g., collinear, with the axis of rotation of the drive rod 20.

Alternatively, one or both of the counterweights (proximal and/or distal) 102, 100 may be concentric, i.e., embodiments may include counterweights (proximal and/or distal) 102, 100 having a center of mass radially spaced from the axis of rotation of the drive rod 20 and aligned with the center of mass of the eccentric abrasive section 28 in the same longitudinal plane, as shown in fig. 6. The radial spacing of the center of mass of the weights may be achieved by offsetting the geometric center of each weight 100, 102 from the axis of rotation of the drive rod 20, wherein each proximal weight 102 and distal weight 100 has a center of mass that is 180 degrees apart from the center of mass of the eccentric abrasive element 28 as shown in fig. 6. The centers of mass of the proximal counterweight 102 and the distal counterweight 100 may be offset by 180 degrees. This weighted arrangement facilitates orbital movement of the abrasive member 28 and facilitates the ability of the abrasive member 28 to cover and open an opening at the stenotic lesion having a diameter significantly larger than the stationary outer diameter of the eccentric enlarged diameter member 28.

Another embodiment may include at least one counterweight 100, 102 having a center of mass that is not necessarily separated from the center of mass of the abrasive component 28 by a 180 degree rotation. One embodiment of the present invention may suppress (dampen) the orbital diameter of the grinding member 28 during high speed rotation by setting the center of mass of at least one counterweight 100, 102 to a zero degree rotation angle with respect to the center of mass of the grinding member 28. This embodiment may be applied to an eccentric or concentric abrasive member 28. For example, suppression in embodiments where the eccentric abrading component 28 is provided with at least one eccentric weight 100, 102, wherein the center of mass of the eccentric abrading component 28 and the at least one eccentric weight 100, 102 are substantially collinear, i.e., are substantially zero degrees of rotational separation. Alternatively, if the grinding member 28 is a concentric embodiment with its center of mass at the axis of rotation of the drive rod 20, at least one counterweight 100, 102 may be provided in a concentric embodiment with its center of mass also at the axis of rotation of the drive rod 20. As another variation, if the grinding member 28 is an eccentric embodiment, with its center of mass offset from the axis of rotation of the drive rod 20, the center of mass of the at least one counterweight has a rotational angle of 180 degrees with respect to the center of mass of the grinding member 28. This embodiment may have at least one weight located on the drive rod 28 with or without a spaced distance between the at least one weight and the abrasive member 28.

Those skilled in the art will readily appreciate the arrangement of the respective counterweights and grinding members 28, and the center of mass disclosed herein above and below may be applied to all forms, shapes and types of grinding members 28, with the counterweights not only promoting orbital movement of the grinding members 28, i.e., increasing the rotational diameter, or weakening the orbital movement of the grinding members 28, i.e., decreasing the rotational diameter.

Importantly, the present invention may allow for the use of a smaller diameter abrasive component 28, coupled with proximal and distal counterweights 102, 100, when opening a swept (swept) diameter lumen, as in the larger diameter abrasive component 28 of the prior art that does not include counterweights 100, 102.

For a given rotational speed of the drive rod 20, one skilled in the art can obtain any desired data by combining and arranging these parameters. Those skilled in the art will recognize that any modification to these parameters will increase or decrease/weaken the diameter of the orbital path created by the abrasive member. Thus, the diameter of the orbital path can be set for individual lumens.

Another embodiment of the present invention may include an abrasive member 28 having a concentric enlarged abrasive member driving a shaft, as described in U.S. patent 5,314,438 to Shturman, the disclosure of which is incorporated herein by reference in its entirety. As a variation, the grinding member 28 of this embodiment may comprise a concentric solid burr mounted on a drive rod, as is known in the art, see U.S. Pat. No. 4,990,134 to Auth. By concentric it is meant herein that the abrasive member 28 is comprised of a coil or a solid, semi-solid burr, i.e., a hollow burr comprising a sphere or ellipsoid or other concentric shape, with the center of mass of the concentric abrasive member 28 on, i.e., collinear with, the rotational axis of the drive rod 20.

Embodiments of the present invention also include two counterweights 100, 102 attached or mounted to the drive rod 20 for encouraging orbital movement of the concentric abrasive member 28. Preferably, the distal counterweight 100 is located at the distal end of the concentric abrasive member 28, while the proximal counterweight 102 is located at the proximal end of the concentric abrasive member 28.

One or both of the proximal and/or distal counterweights 102, 100 may comprise an enlarged diameter section of the drive rod configured in a manner similar to the enlarged eccentric diameter abrasive section 28A shown in fig. 6. In this embodiment, the weights 100, 102 may be hollow, enlarged coils of a drive rod, with mandrels used in the coil winding process. In the case of only one weight, either the proximal end 100 or the distal end 102, is the enlarged eccentric diameter grinding member of the drive rod 20, and the remaining weights may be concentric, i.e., the center of mass is collinear with the axis of rotation of the drive rod and comprises the enlarged diameter member of the drive rod 20, the solid burr may be an at least partially hollow grinding bit, or may be eccentric and comprise a solid burr or an at least partially hollow grinding bit.

Alternatively, one or both of the proximal and distal counterweights 102, 100 may be solid and interface with the coils of the drive rod 20 in a manner known to those skilled in the art. As another alternative, the proximal and distal counterweights 102, 100 may be at least partially hollow.

In one embodiment, in which the abrasive component 28 is concentric, the proximal and distal counterweights 102, 100 are equal in overall mass, each counterweight 102, 100 corresponding to approximately one-half of the overall mass of the concentric abrasive component 28, wherein the proximal counterweight 102 and the distal counterweight 100 are equidistant from the concentric abrasive component 100, wherein the proximal and distal counterweight centroids are equidistant from the rotational axis of the drive rod 20, and wherein the proximal and distal counterweight centroids are equidistant from the concentric abrasive component 28.

The counterweights 100, 102 may be concentric, i.e., spherical or ellipsoidal in shape or other concentric shape, with the center of mass of the counterweights 100, 102 located at the axis of rotation of the drive rod 20.

Preferably, the embodiment includes concentric abrasive member 28, and weights 100, 102 are eccentric, i.e., one embodiment may include proximal and distal weights 102, 100 having centers of mass radially spaced from the rotational axis of drive rod 20, each weight having a center of mass that is offset (offset) from the center of mass of concentric abrasive member 28, the centers of mass and rotational axis of abrasive member 28 being collinear. In addition, the centers of mass of the proximal counterweight 102 and the distal counterweight 100 are aligned in the same longitudinal plane, either above or below the axis of rotation of the drive rod 20, resulting in an "offset" between the center of mass of the abrasive section 28 and the centers of mass of the proximal counterweight 102 and the distal counterweight 100. The centers of mass of proximal counterweight 102 and distal counterweight 100 may be offset 180 degrees relative to either end of the axis of rotation of drive rod 20, or other offset angles known to those skilled in the art.

As with the eccentric abrasive element embodiment, the concentric abrasive element embodiment may accomplish the purpose of radially spacing the centers of mass of the proximal counterweight 102 and the distal counterweight 100 in an eccentric embodiment in a manner that the geometric center of each counterweight 100, 102 is spaced apart from the rotational axis of the drive rod 20, wherein each center of mass of the proximal counterweight 102 and the distal counterweight 100 is spaced apart from the center of mass of the concentric abrasive element and lies in the same longitudinal plane. This weighted embodiment facilitates orbital movement of the abrasive member 28 and facilitates the ability of the abrasive member 28 to cover and open an opening in a stenotic lesion having a diameter larger than the resting outer diameter of the concentric abrasive member 28. As described above, the present invention may allow for the use of a smaller diameter abrasive component 28, used in conjunction with the proximal 102 and distal 100 counterweights, comparable to the prior art large diameter concentric abrasive component 28 in opening a lumen of swept diameter.

Figures 7A-7C depict the position of the center of mass 29 of three cross-sectional slices (shown as cross-sectional fronts) of the eccentric abrading component 28, illustrating the eccentric abrading head 28C shown in figures 5A, 5B, and 5C along with the eccentric weights 100, 102 mounted to the drive rod 20 during high speed rotation. The eccentric abrading element 28 may be divided into a number of thin slices, each slice having its own center of mass. The position shown in fig. 7B is the position of the abrasive member 28 at its maximum cross-sectional diameter (in this case, the maximum diameter of the intermediate portion 35 of the eccentric abrasive member 28), while the positions shown in fig. 7A and 7C are the positions of the distal portion 40 and the proximal portion 30 of the eccentric abrasive member 28, respectively. The centroid of each of these cross-sectional slices is spaced apart from the axis of rotation of the drive rod, which axis of rotation 20 coincides with the center of the guide wire 15. The centroid 29 of each cross-sectional slice also generally coincides with the geometric center of this cross-sectional slice. Fig. 7B shows the slice with the largest cross-sectional diameter. In this slice, both the centroid 29 and the geometric center are located farthest away (i.e., the maximum separation) from the rotational axis of the drive rod 20. Of course, the center of mass of the entire grinding member 28 is composed of the respective centers of mass of the plurality of slices of the enlarged diameter member, and the totality of the centers of mass will be closer to the rotational axis of the drive rod 20 than the center of mass of the slices shown in fig. 7B.

The term "eccentric" as used herein should be understood to mean: refers to the difference in position between the geometric center of the grinding member 28 and the rotational axis of the drive rod, said grinding member 28 comprising an eccentric enlarged diameter section 28A of the drive rod 20, or an eccentric solid burr 28B, or an at least partially hollow eccentric crown or grinding bit 28C, or an eccentric weight; or the difference in position between the center of mass of the eccentric abrading element 28 and the axis of rotation of the drive rod 20, the abrading element 28 comprises an eccentric enlarged diameter element 28A, an eccentric solid burr 28B, an at least partially hollow eccentric crown or abrading head 28C, or eccentric weights 100, 102. At the proper rotational speed, any of these differences will allow the abrading tool 28 to open an opening at a stenotic lesion that is significantly larger than the normal diameter of the abrading tool 28. In addition, in the case of the eccentric abrading part 28 having an irregular geometric shape, the "geometric center" is a concept in which the midpoint of the longest chord that passes through the rotational axis of the driving lever is approximated to the "geometric center", wherein the longest chord means a chord obtained by connecting two points on the outer periphery of the cross section at the position when the eccentric enlarged diameter part has the circumference length of the greatest length. Furthermore, it will be understood by those skilled in the art that the eccentricity, as defined, enables the design of an abrasive member 28 having a concentric profile, but one side of the profile should be heavier than the rest, e.g., the portion of one side of the abrasive member 28 is hollow.

Furthermore, it should be noted that concentric as used herein means that the grinding member 28 and/or the arrangements 100, 102 have a center of mass that is located on the axis of rotation of the drive rod 20, i.e., are collinear, and that the profile is in fact symmetrical.

Figures 8 and 9 illustrate the generally spiral orbital path of various embodiments of the eccentric abrading head 28 of the present invention, the abrading head 28 being shown as an abrading head 28 that has been advanced relative to the guidewire 15. The extent of the helical path (pitch) shown in figures 8, 9 is exaggerated for illustrative purposes-in practice, the helical path of each eccentric enlarged abrading head 28 removes only a very thin layer of tissue as it passes over the tissue removal surface 37, and as the device is repeatedly moved back and forth across the stenosis, the eccentric enlarged abrading head 28 creates many such helical paths to fully open the stenosis. Figure 9 illustrates three different rotational positions of the eccentric enlarged abrading head 28 of the rotational atherectomy device of the present invention. At each location, the abrasive surface of eccentric enlarged abrading head 28 contacts plaque "P" so that it is removed-three different plaque contact points, designated by "P", for the three locations, which points are designated B1, B2, and B3. It should be noted that each point is generally at the same location on the polishing surface of eccentric enlarged abrading head 28 that is in contact with the tissue-the portion of tissue removing surface 37 is a radially large distance from the axis of rotation of the drive rod.

The present invention should not be considered limited to the above-mentioned examples, but rather should be understood to cover all aspects of the invention as fairly set out. Various modifications, equivalent processes, as well as structural changes suitable for use in the present invention will be readily apparent to those skilled in the art upon a reading of the present specification.

Claims (6)

1. An atherectomy device for creating a fixed diameter opening in an arterial stenosis, comprising:

a guidewire having a maximum diameter less than the diameter of the artery;

a flexibly extending, rotatable drive shaft advanceable over the guide wire, the drive shaft having a rotational axis and abrasive element, the abrasive element comprising a concentrically arranged abrasive element profile and an abrasive element first material having a density at a first end of the abrasive element and an abrasive element second material having a density greater than the abrasive element first material at a second end of the abrasive element, and an abrasive element centroid spaced apart by the abrasive element first material and the abrasive element second material density in a longitudinal plane from the drive shaft rotational axis to the drive shaft first end; a proximal counterweight is disposed at the proximal end of the grinding member, the proximal counterweight having a concentrically disposed proximal counterweight profile and a proximal counterweight first material having a density at a first end of the proximal counterweight and a proximal counterweight second material having a density greater than the proximal counterweight first material at a second end of the proximal counterweight, and a proximal counterweight center of mass spaced from the drive rod axis of rotation to the proximal counterweight first end by the density of the proximal counterweight first material and the proximal counterweight second material, the proximal counterweight center of mass and the grinding member center of mass being spaced in a same longitudinal plane of the drive rod axis of rotation and being at a 180 degree angle about the drive shaft axis of rotation;

a distal counterweight having a concentrically disposed distal counterweight profile and a distal counterweight first material having a density at a distal counterweight first end and a distal counterweight second material having a density higher than the distal counterweight first material at a distal counterweight second end, and a distal counterweight center of mass spaced from the drive rod axis of rotation to the distal counterweight first end by the density of the distal counterweight first material and the distal counterweight second material, the distal counterweight center of mass and the abrasive element center of mass and the proximal counterweight center of mass being spaced in a same longitudinal plane of the drive rod axis of rotation and being spaced at a 180 degree angle from the abrasive element center of mass about the drive shaft axis of rotation.

2. The rotational atherectomy device of claim 1, wherein: also, the radial spacing of the proximal counterweight center of mass comprises a first distance from the center of mass to the axis of rotation of the drive rod, and the radial spacing of the distal counterweight center of mass from the axis of rotation of the drive rod comprises a second distance from the distal counterweight center of mass to the axis of rotation of the drive rod, the first and second distances being equal.

3. An atherectomy device for creating a fixed diameter opening in an arterial stenosis, comprising:

a guidewire having a maximum diameter less than the diameter of the artery;

a flexibly extending, rotatable drive shaft advanceable over the guide wire, the drive shaft having a rotational axis and abrasive element, the abrasive element comprising a concentrically arranged abrasive element profile and an abrasive element first material having a density at a first end of the abrasive element and an abrasive element second material having a density greater than the abrasive element first material at a second end of the abrasive element, and an abrasive element centroid spaced apart by the abrasive element first material and the abrasive element second material density in a longitudinal plane from the drive shaft rotational axis to the drive shaft first end; a near-end counterweight is arranged at the near end of the grinding part, the near-end counterweight is provided with a near-end counterweight appearance which is concentrically arranged and a near-end counterweight mass center which is radially spaced from the rotating shaft of the driving rod under the action of the near-end counterweight appearance which is concentrically arranged, the near-end counterweight mass centers are radially spaced from the rotating shaft of the driving rod and are on the same longitudinal plane with the grinding part mass center, and an angle of 180 degrees is formed between the near-end counterweight mass center and the rotating shaft of the driving rod;

and a far-end counterweight is arranged at the far end of the grinding part, the far-end counterweight is provided with a far-end counterweight appearance which is concentrically arranged and a far-end counterweight mass center which is radially spaced from the rotating shaft of the driving rod under the action of the far-end counterweight appearance which is concentrically arranged, the far-end counterweight mass centers are radially spaced from the rotating shaft of the driving rod and are on the same longitudinal plane with the mass center of the grinding part, and an angle of 180 degrees is formed between the far-end counterweight mass center and the rotating shaft of the driving rod.

4. The rotational atherectomy device of claim 3, wherein: also, the radial spacing of the proximal counterweight center of mass comprises a first distance from the center of mass to the axis of rotation of the drive rod, and the radial spacing of the distal counterweight center of mass from the axis of rotation of the drive rod comprises a second distance from the distal counterweight center of mass to the axis of rotation of the drive rod, the first and second distances being equal.

5. An atherectomy device for creating a fixed diameter opening in an arterial stenosis, comprising:

a guidewire having a maximum diameter less than the diameter of the artery;

a flexibly extending, rotatable drive shaft advanceable over the guide wire, the drive shaft having a rotational axis and abrasive element, the abrasive element comprising a concentrically arranged abrasive element profile and an abrasive element first material having a density at a first end of the abrasive element and an abrasive element second material having a density greater than the abrasive element first material at a second end of the abrasive element, and an abrasive element centroid spaced apart by the abrasive element first material and the abrasive element second material density in a longitudinal plane from the drive shaft rotational axis to the drive shaft first end;

a near-end counterweight is arranged at the near end of the grinding part, the near-end counterweight is provided with a near-end counterweight appearance which is concentrically arranged and a near-end counterweight mass center which is radially spaced from the rotating shaft of the driving rod under the action of the near-end counterweight appearance which is concentrically arranged, the near-end counterweight mass centers are radially spaced from the rotating shaft of the driving rod and are on the same longitudinal plane with the grinding part mass center, and an angle of 180 degrees is formed between the near-end counterweight mass center and the rotating shaft of the driving rod;

a proximal counterweight is disposed at the proximal end of the grinding member, the proximal counterweight having a concentrically disposed proximal counterweight profile and a proximal counterweight first material having a density at a first end of the proximal counterweight and a proximal counterweight second material having a density greater than the proximal counterweight first material at a second end of the proximal counterweight, and a proximal counterweight center of mass spaced from the drive rod axis of rotation to the proximal counterweight first end by the density of the proximal counterweight first material and the proximal counterweight second material, the proximal counterweight center of mass and the grinding member center of mass being spaced in a same longitudinal plane of the drive rod axis of rotation and being at a 180 degree angle about the drive shaft axis of rotation;

a distal counterweight having a concentrically disposed distal counterweight profile and a distal counterweight first material having a density at a distal counterweight first end and a distal counterweight second material having a density higher than the distal counterweight first material at a distal counterweight second end, and a distal counterweight center of mass spaced from the drive rod axis of rotation to the distal counterweight first end by the density of the distal counterweight first material and the distal counterweight second material, the distal counterweight center of mass and the abrasive element center of mass and the proximal counterweight center of mass being spaced in a same longitudinal plane of the drive rod axis of rotation and being spaced at a 180 degree angle from the abrasive element center of mass about the drive shaft axis of rotation.

6. The rotational atherectomy device of claim 5, wherein: also, the radial spacing of the proximal counterweight center of mass comprises a first distance from the center of mass to the axis of rotation of the drive rod, and the radial spacing of the distal counterweight center of mass from the axis of rotation of the drive rod comprises a second distance from the distal counterweight center of mass to the axis of rotation of the drive rod, the first and second distances being equal.