HK1158917B - Method and apparatus for increasing rotational amplitude of abrasive element on high-speed rotational atherectomy device - Google Patents

Description

Method and apparatus for increasing rotational amplitude of abrasive member of high-speed rotational atherectomy device

Cross Reference to Related Applications

This application claims priority to provisional application No. 61/046,145, entitled, by the same name, filed on 18.4.2008, the entire contents of which are incorporated herein by reference.

Technical Field

The invention relates to a method and a device for improving the rotation amplitude of an abrasive part of a high-speed rotational atherectomy device.

Background

Various techniques and instruments have been developed for removing or repairing tissue in arteries and similar body passageways. One common purpose of such techniques and instruments is to remove atherosclerotic plaques within the arteries of a patient. Atherosclerosis is characterized by an increase in the deposition of fat (atheroma) in the intimal layer (endothelium) of a patient's blood vessel. Generally, over time, relatively soft, cholesterol-rich atherosclerotic material begins to deposit, and gradually hardens into calcified atherosclerotic plaques. This atheroma restricts the flow of blood and is therefore commonly referred to as stenotic lesions or stenoses, and the obstruction is referred to as a stenosis. If left untreated, this stenosis can lead to angina, hypertension, myocardial infarction, stroke, etc.

Rotational atherectomy has become a common technique for removing such stenoses. This procedure is most often used to open the coronary calcified lesion channel. In most cases, rotational atherectomy is not used alone, but is accompanied by balloon angioplasty (balloon angioplasty), which is usually followed by the implantation of a stent to assist in maintaining patency of the open artery. For non-calcified lesions, balloon angioplasty is mostly used alone to open an artery, usually with the implantation of a stent to maintain patency of the opened artery. However, studies have shown that a significant proportion of patients who undergo balloon angioplasty and have stents implanted in their arteries experience stent restenosis, most often due to the development of scar tissue within the stent over time resulting in the blockage of the stent. In such cases, balloon angioplasty within the stent is not very effective, and thus atherectomy is the preferred procedure for removing additional scar tissue from the stent to restore permeability to the artery.

Several types of rotational atherectomy devices have been developed for the removal of stenotic material. In one type of device, a concentric elliptical cone is coated with an abrasive material such as diamond particles near the distal end of a flexible drive shaft, as described in U.S. patent 4990134 (Auth). The cone rotates at high speed (typically, e.g., in the range of about 150000 and 190000 rpm) as it advances through the stenosis. But the cone will block the blood flow when it clears the stenotic tissue. Once the cone is advanced through the stenosis, the artery will be opened with a diameter equal to or slightly larger than the maximum outer diameter of the cone. Often, because the cones have a fixed resting diameter, more than one size of cone needs to be used to open the artery to the desired diameter. The Auth patent does not disclose other means of varying, meeting the requirement that the swept diameter be varied during high speed rotation, or that the diameter be greater than the rest diameter of the cone.

Us patent 5681336 (Clement) discloses an eccentric outer surface portion provided with an abrasive tissue removal cone secured by a suitable adhesive. This configuration is limited, but because, as explained by Clement at column 3, lines 53-55, the asymmetric cone rotates at a "lower speed" than the high speed rotational atherectomy device to counteract heat and imbalance. That is, for a solid cone of a given size and mass, it is not possible to rotate the cone at the high speeds used in rotational atherectomy procedures, i.e., in the rotational speed range of 20000-. More importantly, the deviation of the center of mass of the rotational axis of the drive shaft will result in the formation of significant and undesirable centrifugal forces, excessive pressure on the arterial wall, and excessive heat and particles. As with the Auth patent, the size of the cone is fixed and more than one size cone needs to be used to open the target lumen to the desired diameter.

Us patents 6132444 (Shturman) and 6494890 (Shturman) disclose, inter alia, rotational atherectomy devices having a drive shaft with an enlarged eccentric portion wherein at least a segment of the enlarged portion is covered with an abrasive material. The abrasive segment can clear stenotic tissue from the artery when the rotation is adjusted. The device can open the artery to a larger diameter than the enlarged eccentric, in part because of orbital rotation in high speed operation. Orbital rotation is primarily due to the center of mass of the enlarged eccentric being offset from the drive axis of the rotating shaft. Because the enlarged eccentric contains drive shaft wires that are not bonded together, the enlarged eccentric to the drive shaft can bend when placed in a stenosis, or when operated at high speeds. This curvature allows a larger diameter to be opened during high speed operation, but the actual diameter of the artery abraded is less controlled than desired. The disclosures of each of U.S. patents 6132444 and 6494890 are hereby incorporated by reference in their entirety.

Disclosure of Invention

A first embodiment is a high-speed rotational atherectomy device for opening a stenosis in an artery, the device having a given diameter, comprising: a guidewire having a maximum diameter smaller than the diameter of the artery; a flexible, elongated, rotatable drive shaft advanceable along the guide wire; a grinding member provided on the drive shaft; a proximal counterweight attached to the drive shaft, the proximal counterweight being spaced proximal to the abrasive element by an adjustable proximal spacing; and a tip weight attached to the drive shaft, the tip weight being spaced away from the abrasive component by an adjustable tip.

A second embodiment is a method of obtaining a diameter of rotation within a chamber using an abrasive section of a flexible drive shaft, wherein the rotation is greater than a resting diameter of the abrasive section, comprising: providing a guidewire having a diameter less than the lumen diameter; providing a flexible, elongated, rotatable drive shaft advanceable along a guide wire; the drive shaft has a rotational axis and an eccentric abrasive member; providing a proximal counterweight spaced proximally of the eccentric abrasive element; providing a distal counterweight spaced away from the eccentric abrading component; retracting the guide wire; and rotates the drive shaft at high speed.

A third embodiment is a method of obtaining a rotating diameter within a cavity using an abrasive portion of a flexible drive shaft, wherein the rotating diameter is greater than a resting diameter of the abrasive portion, comprising: providing a guidewire having a diameter less than the lumen diameter; providing a flexible, elongated, rotatable drive shaft advanceable along a guide wire; the drive shaft having a rotational axis and an eccentric abrasive member, the abrasive member including an eccentric enlarged portion of the drive shaft; providing a proximal counterweight spaced proximally of the eccentric abrasive element, the proximal counterweight including an eccentric enlarged portion of the drive shaft; providing a tip weight spaced away from the eccentric abrasive component, the tip weight including an eccentric enlarged portion of the drive shaft; retracting the guide wire; and rotates the drive shaft at high speed.

Drawings

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

FIG. 2 is a perspective, exploded view of a flexible, eccentric enlarged portion of a known drive shaft;

FIG. 3 is a broken away, longitudinal cross-sectional view of an eccentric enlarged portion of a known drive shaft;

FIG. 4 is a split, longitudinal cross-sectional view of the flexibility of a prior art solid eccentric enlarged cone secured to a drive shaft;

FIG. 5A is a perspective view of a known eccentric abrading head or crown attached to a drive shaft;

FIG. 5B is a bottom view of a known eccentric abrading head or crown attached to a drive shaft;

FIG. 5C is a longitudinal cross-sectional view of a known eccentric abrading head or crown attached to a drive shaft;

FIG. 6 is a longitudinal cross-sectional view of an exemplary abrading head;

FIG. 7A is a cross-sectional view of an exemplary polishing head;

FIG. 7B is another cross-sectional view of the exemplary polishing head;

FIG. 7C is another cross-sectional view of the exemplary polishing head;

FIG. 8 is a transverse cross-sectional view showing 3 different positions of the fast rotating abrasive section of the eccentric rotational atherectomy device;

FIG. 9 is a schematic view of the 3 monks of the rapid rotation polishing section of FIG. 8;

FIG. 10 is a cross-sectional view of the eccentric abrasive component, eccentric proximal counterweight, and eccentric distal counterweight;

FIG. 11 is a cross-sectional view of an eccentric abrasive component, eccentric proximal counterweight, and concentric distal counterweight;

FIG. 12 is a cross-sectional view of an eccentric abrasive component, concentric proximal counterweight, and eccentric distal counterweight;

FIG. 13 is a cross-sectional view of an eccentric abrasive component, concentric proximal counterweight, and concentric distal counterweight;

FIG. 14 is a cross-sectional view of a concentric abrasive member, an eccentric proximal counterweight, and an eccentric distal counterweight;

FIG. 15 is a cross-sectional view of a concentric abrasive member, eccentric proximal counterweight, and concentric distal counterweight;

FIG. 16 is a cross-sectional view of a concentric abrasive member, concentric proximal counterweight, and eccentric distal counterweight;

FIG. 17 is a cross-sectional view of a concentric abrasive member, concentric proximal counterweight, and concentric distal counterweight;

FIG. 18 is a schematic view of the abrasive component and counterweight, with a distance D1 between the proximal counterweight and the center of mass of the abrasive component and a distance D2 between the distal counterweight and the center of mass of the abrasive component;

FIG. 19 is a cross-sectional view of a guidewire extending beyond the distal end of the drive shaft during operation;

FIG. 20 is a cross-sectional view of the lead retracted to the end weight prior to and/or during operation;

FIG. 21 is a cross-sectional view of the wire retracted to the abrasive member prior to and/or during operation;

FIG. 22 is a cross-sectional view of the lead retracted to the proximal counterweight prior to and/or during operation;

fig. 23 is a cross-sectional view of a lead retracted beyond the proximal counterweight prior to and/or during operation.

Detailed Description

While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be noted, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Figure 1 shows a typical rotational atherectomy device. The device includes a handpiece 10, an elongated, flexible drive shaft 20 having an abrasive section 28, the abrasive section 28 including an eccentrically enlarged diameter section 28A, and an elongated conduit 13 extending from the distal end of the handpiece 10. The drive shaft 20 and its eccentrically enlarged diameter portion 28 are constructed of a helically coiled wire. The catheter 13 has a lumen in which most of the length of the drive shaft 20 is accommodated except for an enlarged diameter portion 28A and a short portion away from the enlarged diameter portion 28. The drive shaft 20 also has a lumen such that the drive shaft 20 can be advanced and rotated along the guide wire 15. A liquid supply line 17 may be provided to introduce a cooling and lubricating solution (typically saline or other biocompatible liquid) into the conduit 13.

The handpiece 10 preferably contains a turbine (or similar rotational drive mechanism) for rotating the drive shaft 20 at high speed. The handpiece 10 is typically connectable to a power source, such as compressed air delivered through a tube 16. Fiber optic cables 23 may also be provided to monitor the rotational speed of the turbine and drive shaft 20. Details of such handpieces and related devices are well known in the art and are described, for example, in U.S. patent 5314407 to Auth. The handpiece 10 also preferably includes a control button 11 for advancing and retracting the turbine and drive shaft 20 in view of the conduit 13 and handpiece housing.

Fig. 2-3 show details of the grinding section 28 including an eccentrically enlarged diameter section 28A. The drive shaft 20 is constructed of one or more helically bent wires 18 and defines a wire lumen 19 and an empty recess 25 at an enlarged diameter portion 28A. The empty recess 25 is substantially empty except for the wire 15 passing through the empty recess 25. As shown, abrading portion 28 is an eccentrically enlarged diameter portion 28A having a proximal portion 30, a middle portion 35, and a distal portion 40, with a tissue clearance surface 37 thereon. The coils 31 of the proximal portion 30 of the eccentrically enlarged diameter portion 28A preferably have a diameter that increases progressively at a substantially constant rate, and thus are generally conically shaped. The coils 41 of the tip 40 preferably have a diameter that decreases progressively at a substantially constant rate, and thus generally form a conical shape. The coils 36 of the intermediate section 35 are provided with a stepped diameter to provide a generally convex outer surface shaped to provide a smooth transition between the proximal and distal tapered portions of the enlarged diameter section 28A of the drive shaft 20.

At least a portion of the abrading segment 28, shown as an eccentric enlarged diameter segment 28A (preferably a central segment 35) having an outer surface 37 that can be debrided. Preferably, the tissue removal surface contains a coating 37 of abrasive material 24 to define the tissue removal segment of the drive shaft 20. The abrasive material may be any suitable material, such as diamond powder, fused silica, titanium nitride, tungsten carbide, alumina, boron carbide, or other ceramic material. Preferably, the abrasive material is secured directly to the coils of the drive shaft 20 from diamond chips (or diamond powder particles) by a suitable adhesive layer 26, such securement being achieved by using well known techniques such as conventional electroplating or fusing techniques (see, e.g., U.S. Pat. No. 4,018,576). Alternatively, the tissue-removing outer surface may simply be a roughened coil to provide a suitable abrasive surface. Alternatively, the outer surface is etched or cut (e.g., by a laser) to provide a small but sharp cut surface. Other similar techniques may be used to provide a suitable tissue removal surface.

Fig. 4 illustrates another known abrasive portion 28, shown as an eccentric solid, or at least partially hollow cone 28B. A solid, or at least partially hollow, grinding cone 28B is secured to the drive shaft 20 by means well known in the art and contains a coating of abrasive material 24 secured to the surface by a suitable adhesive 26.

Figures 5A, 5B and 5C illustrate another known abrasive surface 28, as described in U.S. patent application 11/761128 to Thatcher et al, including an eccentric abrading head or crown 28C, the contents of which are incorporated herein by reference in their entirety. The cavity 23 is crimped to the drive shaft 20 and may contain a hollow portion 25 to assist in moving the center of mass away from, or closer to, the axis of rotation of the drive shaft 20. The abrasive section 28C includes a proximal section 30, a middle section 35, and a distal section 40, the proximal section 30 and the distal section 40 progressively moving away from the middle section 35 and appearing to have a cylindrical shape.

Thus, one example of an application includes a grinding section 28, which in turn includes an eccentric enlarged section 28A of the drive shaft, or an eccentric solid crown or grinding head 28C or eccentric cone 28B affixed to the drive shaft, wherein the grinding section 28 has a radius distributed about the axis of rotation of the drive shaft 20 that promotes the ability of the device to open stenotic lesions to a diameter substantially larger than the outer diameter of the grinding section 28. This may be accomplished by distributing the center of mass of the abrading segment 28, i.e., the eccentric enlarged diameter portion of the drive shaft 20, or the eccentric solid abrading head or crown 28C, or cone 28B, affixed to the drive shaft 20, away from the axis of rotation of the drive shaft 20. Alternatively, by providing the grinding section 28 with different combinations of materials, the center of mass of the grinding section 28 may be radially distributed around the rotational axis of the drive shaft, wherein at least one side of the grinding section 28 is composed of a heavier or more material than the other side, which causes the eccentricity as defined herein. Those skilled in the art will recognize that the eccentricity, i.e., center of mass offset from the axis of rotation of the drive shaft, created by the use of different materials in the configuration of abrasive section 28 applies to any configuration of abrasive section 28 discussed herein, whether concentric, eccentric, solid cone, partially hollow crown or enlargement of the abrading head or drive shaft, or equivalent configurations thereof.

Further, this embodiment may include at least one weight located on and fixedly attached to the drive shaft to facilitate the orbital motion of the eccentric abrading portion. At least one such weight may be located proximally of the abrading portion and at least another such weight may be located distally of the abrading portion.

In one example, as shown in fig. 6, the grinding portion 28 is shown as an eccentrically enlarged diameter portion 28A of the drive shaft 20. A tip weight 100 is located at the distal end of the abrasive section 28 and a proximal weight 102 is located at the proximal end of the abrasive section. Alternatively, examples may include only the end weight 100, operatively combined with the abrasive section 28, or the proximal weight 102, operatively combined with the abrasive section 28.

As shown in fig. 6, the weights 100, 102 may be solid and eccentric cones, although many alternatives exist in the present application.

For example, one or both of the proximal and distal counterweights 100, 102 may comprise an enlarged diameter portion of the drive shaft, in a pattern such as an enlarged eccentric diameter abrasive portion 28A. In the present application, the counterweights 100, 102 are substantially hollow, and the enlarged coils of the drive shaft 20 are formed by using a mandrel during the coil winding process. In the case of only one proximal counterweight 102 or distal counterweight 100, the counterweight is an enlarged eccentric diameter abrading portion of the drive shaft 20, and the remaining counterweights can be concentric, i.e., the center of mass is collinear with the axis of rotation of the drive shaft and comprises an enlarged diameter portion of the drive shaft, a solid crown or an at least partially hollow crown, or eccentric and comprises a solid cone or an at least partially hollow abrading head.

Alternatively, as shown in FIG. 6, one or both of the proximal and distal counterweights 100, 102 may be solid and secured to the coils of the drive shaft 20 by means well known to those skilled in the art. As a further alternative, the proximal and distal counterweights 100, 102 may be at least partially hollow.

Still alternatively, one or both of the weights 100, 102 may be constructed of different combinations of materials, wherein one side of at least one of the weights 100, 102 is constructed of a heavier or more material than the other side, which creates an eccentricity as defined herein. As will be appreciated by those skilled in the art, the eccentricity created by using different materials in the weights 100, 102, i.e., the center of mass is offset from the rotational axis of the drive shaft, applies to any configuration of the weights 100, 102, whether concentric, eccentric, solid cone, partially hollow crown or abrading head or enlargement of the drive shaft, or equivalent configuration thereof.

In one example, the proximal and distal counterweights 100, 102 as shown in fig. 6 are substantially equal in overall mass, each of the counterweights 100, 102 being approximately one-half of the overall mass of the abrasive section 28, wherein the proximal and distal counterweights 100, 102 are equidistant from the abrasive section 28, wherein the proximal and distal counterweights 100, 102 contain a center of mass that is equidistant from the axis of rotation of the drive shaft 20, and wherein the proximal and distal counterweights 100, 102 contain a center of mass that is equidistant from the center of mass of the eccentric abrasive section 28. Other and equivalent mass distributions between the grinding section 28 and the counterweight for controlling the orbital rotation diameter of the grinding section 28 in high speed rotation will be readily apparent to those skilled in the art.

Further, one or both of the counterweights (proximal and/or distal) 100, 102 may be concentric, i.e., spherical or ellipsoidal in cross-section or otherwise concentric, with one or both of the counterweights (proximal and/or distal) 100, 102 having a center of mass that is substantially at, i.e., collinear with, the axis of rotation of the drive shaft 20.

Alternatively, one or both of the counterweights 100, 102 (proximal and/or distal) may be eccentric, i.e., the structure may contain counterweights 100, 102 having centers of mass distributed about the rotational axis of the drive shaft 20 (proximal and/or distal) and aligned in the same longitudinal plane, such as the center of mass of the eccentric abrasive section 28 shown in FIG. 6. The radial distribution of the center of mass of the counterweight can be achieved by distributing the geometric center of each of the counterweights 100, 102 away from the rotational axis of the drive shaft 20, wherein the proximal counterweight 102 and the distal counterweight 100 each have a center of mass that is separated from the center of mass of the eccentric abrasive section 28 by a 180 ° angle of rotation as shown in fig. 6. The centers of mass of the proximal counterweight 102 and the distal counterweight 100 may be offset by 180 °. This weighted arrangement facilitates the orbital movement of the abrasive section 28 and the ability of the abrasive section 28 to sweep and open the stenotic lesion to a diameter substantially larger than the resting diameter of the eccentrically enlarged diameter section 28.

Another example may include at least one counterweight 100, 102, and the counterweights 100, 102 may or may not have a center of mass that is separated from the center of mass of the grinding section 28 by a rotational angle of 180 °. One example may inhibit the orbital rotation diameter of the grinding section 28 during high speed rotation by moving the center of mass of at least one of the counterweights 100, 102 away from the center of mass of the grinding section 28 by a rotational angle of 0 °. This applies both if the grinding section 28 is eccentric or concentric. For example, for the eccentric abrading portion 28, inhibition may be achieved by fixing at least one of the eccentric weights 100, 102, wherein the center of mass of the eccentric abrading portion 28 and at least one of the eccentric weights 100, 102 are substantially collinear, i.e., have an included angle of rotation of substantially 0 °.

Alternatively, if the grinding section 28 is provided concentrically with its center of mass located on the rotational axis of the drive shaft 20, at least one of the counterweights 100, 102 may be concentric with its center of mass located on the rotational axis of the drive shaft 20. As a further alternative, if the grinding section 28 is provided eccentric with its center of mass offset from the rotational axis of the drive shaft 20, at least one counterweight is provided with its center of mass offset 180 ° from the center of mass of the grinding section 28. This example may provide at least one counterweight on the drive shaft 20, with or without a gap between the counterweight and the grinding section 28.

Those skilled in the art will readily recognize that the relative configurations of the counterweights and grinding section 28 and its center of mass disclosed herein below may be applied to all forms, profiles and types of grinding sections 28 and counterweights discussed herein to facilitate, i.e., enhance, the rotational diameter of the grinding section 28 orbital motion, or to inhibit, i.e., reduce, the rotational diameter.

It is apparent that the present application, as described herein, may use a smaller diameter abrasive portion 28, along with proximal and distal counterweights 100, 102, while the open swept diameter is equivalent to the cavity of a larger diameter abrasive portion 28 known to not contain counterweights 100, 102.

Those skilled in the art will recognize various combinations and permutations of these parameters for a given rotational speed of the drive shaft 20. One skilled in the art will recognize that any modification of these parameters will increase or decrease/inhibit the diameter of the grinding section orbital path. In this way, the diameter of the track path can be customized for a single cavity.

Another example may include a grinding section 28, the grinding section 28 being comprised of a concentric enlarged grinding section of a drive shaft as described in U.S. patent 5314438 to Shturman, the disclosure of which is incorporated herein by reference in its entirety. Alternatively, the grinding section 28 of Shturman may comprise a concentric solid cone fixed to a drive shaft, as is well known to those skilled in the art, see, for example, U.S. patent 4990134 to Auth. Concentric here means that the grinding section 28, whether formed by a coil, or solid or semi-solid, i.e., comprising a hollow cone having a spherical or ellipsoidal profile or other concentric shape, the concentric grinding section 28 has a center of mass that lies on, i.e., is collinear with, the rotational axis of the drive shaft 20.

Further, this embodiment includes two counterweights 100, 102 attached or otherwise secured to the drive shaft 20 to facilitate the orbital motion of the concentric abrasive section 28. Preferably, the tip weight 100 is located at the proximal end of the concentric abrasive section 28 and the proximal weight 102 is located at the distal end of the concentric abrasive section 28.

One or both of the proximal and/or distal counterweights 100, 102 may comprise an enlarged diameter portion of the drive shaft, forming a pattern of enlarged eccentric diameter abrasive sections 28A as shown in fig. 6. In the present application, the weights 100, 102 may be substantially hollow, with an enlarged coil of the drive shaft 20 formed by using a mandrel during the coil winding process. In the case of only one proximal counterweight 102 or distal counterweight 100, the counterweight is an enlarged eccentric diameter abrading portion of the drive shaft 20, and the remaining counterweights can be concentric, i.e., the center of mass is collinear with the axis of rotation of the drive shaft and comprises an enlarged diameter portion of the drive shaft, a solid crown or an at least partially hollow crown, or eccentric and comprises a solid cone or an at least partially hollow abrading head.

Alternatively, the proximal and distal counterweights 100, 102 may be solid and secured to the coils of the drive shaft 20 by methods well known to those skilled in the art. As a further alternative, the proximal and distal counterweights 100, 102 may be at least partially hollow.

In one example, where the abrasive section 28 is concentric, the proximal and distal counterweights 100, 102 are substantially equal in overall mass, each of the counterweights 100, 102 is approximately one-half of the overall mass of the concentric abrasive section 28, where the proximal counterweight 102 and the distal counterweight 100 are equidistant from the concentric abrasive section 28, where the proximal and distal centroids are equidistant from the rotational axis of the drive shaft 20, and the proximal and distal centroids are equidistant from the concentric abrasive section 28.

The counterweights 100, 102 may be concentric, i.e., spherical or ellipsoidal or otherwise concentric in cross-section, with the center of mass of the counterweights 100, 102 being substantially on the axis of rotation of the drive shaft 20.

Preferably, in this example, including the concentric abrasive portion 28, the counterweights 100, 102 are eccentric, i.e., the proximal counterweight 102 and the distal counterweight 100 can have a radial distribution about the rotational axis of the drive shaft 20, with the center of mass of each being offset in the same longitudinal plane, and with the center of mass of the concentric abrasive portion 28 being collinear with the rotational axis in the same longitudinal plane. Further, the center of mass of both the proximal counterweight 102 and the distal counterweight 100 may be above or below the rotational axis of the drive shaft 20, and the center of mass of both are in the same longitudinal plane, creating an "offset" between the center of mass of the abrasive section 28 and the center of mass of the proximal counterweight 102 and the distal counterweight 100. The center of mass of the proximal counterweight 102 and the distal counterweight 100 can be offset 180 ° about the rotational axis of the drive shaft 20, or other degrees as can be readily appreciated by those skilled in the art.

Similar to the case of the eccentric abrading portion, the case of the concentric abrading portion may be accomplished by offsetting the geometric center of each of the counterweights 100, 102 from the rotational axis of the drive shaft 20, wherein the center of mass of each of the proximal counterweight 102 and the distal counterweight 100 is offset from the center of mass of the concentric abrading portion and is in the same longitudinal plane. This counter-weighting facilitates the orbital motion of the abrasive section 28 and the ability of the abrasive section 28 to sweep and open the stenotic lesion to a diameter substantially larger than the resting diameter of the concentric enlarged diameter section 28. As described above, the present application enables the use of a smaller diameter abrasive portion 28, along with proximal counterweight 102 and distal counterweight 100, while opening a lumen, the swept diameter of which is comparable to known larger diameter concentric abrasive portion 28 references.

Fig. 7A-7C depict the position of the center of mass 29 of the 3 sections of the eccentric abrading portion 28 (shown as the front of the transverse section), as shown in fig. 5A, 5B, and 5C, as described herein, when the eccentric abrading head 28C with the eccentric weights 100, 102 secured to the drive shaft 20 is rotating at high speeds. The eccentric abrasive section 28 may be divided into a number of such lamellae, each having its centroid. Fig. 7B shows the position where the abrasive section 28 has the largest cross-sectional diameter (in this case, the largest diameter of the central section 35 of the eccentric abrasive section 28), and fig. 7A and 7C show the distal end portion 40 and the proximal end portion 30 of the eccentric abrasive section 28, respectively. In each of these sections, the center of mass 29 is located away from the axis of rotation of the drive shaft 20, which is coiled outside the center of the wire 15. The centroid 29 of each cross-section also generally coincides with the geometric center of the cross-sections. Fig. 7B shows the portion having the largest cross-sectional diameter. In this section, both the centroid 29 and the geometric center are located farthest from the rotational axis of the drive shaft 20 (i.e., as far from the distribution as possible). Of course, the center of mass of the entire grinding section 28 is a combination of multiple partial individual centers of mass of the enlarged diameter section, and therefore, the overall center of mass will be closer to the rotational axis of the drive shaft 20 than the center of mass of the section shown in fig. 7B.

It should be appreciated that the term "eccentric" is defined herein as including a difference in the position of the eccentric enlarged diameter portion 28A of the drive shaft 20, or the eccentric solid cone 28B, or the eccentric at least partially hollow crown or abrading head 28C, or the eccentric weighted abrading portion 28 relative to the geometric center of the rotational axis of the drive shaft, or including a difference in the position of the eccentric enlarged diameter portion 28A, or the eccentric solid cone 28B, or the eccentric at least partially hollow crown or abrading head 28C, or the eccentric weighted abrading portion 28, 102 relative to the center of mass of the rotational axis of the drive shaft 20. Any of these differences, at the proper rotational speed, will allow the abrasive section 28 to open the stenosis to a diameter substantially greater than the apparent diameter (nominal diameter) of the abrasive section 28. Further, for the eccentric abrasive section 28 having an irregular geometric shape, its "geometric center" can be roughly determined by locating the midpoint of the longest chord drawn through the axis of rotation of the drive shaft and connecting two points on its cross section where the outer periphery of the eccentric enlarged diameter section has the greatest length. Further, it will be apparent to those skilled in the art that the eccentricity, as defined herein, may also be substantially concentrically curved, but that one side of the curved surface passes, e.g., by hollowing out a portion of one side of the abrasive portion 28, more heavily than the other side of the abrasive portion 28.

Further, it is also noted that concentricity, as used herein, is defined as the center of mass of the grinding section 28 and/or the counterweights 100, 102 being on the axis of rotation of the drive shaft 20, i.e., collinear with the axis of rotation of the drive shaft 20, and substantially symmetrical to the curved surface.

Figures 8 and 9 show the helical track created by the eccentric abrading head 28 showing that the abrading head 28 has advanced along the guidewire 15 relative to the guidewire 15. The lines of the spiral tracks in fig. 8 and 9 are exaggerated for illustrative purposes. In fact, the helical trajectory of the eccentric enlarged abrading head 28 removes only a thin layer of tissue through the tissue removal surface 37, and the eccentric enlarged abrading head 28 creates many such helical paths as the device is repeatedly moved forward and backward along the stenosis to eventually open the stenosis.

Figure 9 shows 3 different rotational positions of the eccentric enlarged abrading head 28 of the rotational atherectomy device. At each location, plaque "P" that is in contact with the abrasive surface of the eccentric enlarged abrading head 28 is removed. The 3 locations are distinguished by 3 distinct points of contact with the plaque "P", which are labeled B1, B2, and B3 in the figure. Note that at each point, it is generally the same portion of the abrasive surface of the eccentric enlarged abrading head 28 that is in contact with the tissue removing surface 37 that is as far as possible radially away from the rotational axis of the drive shaft.

As described above, the term "eccentricity" is used to indicate a factor of which the center of mass is deviated from the rotational axis of the drive shaft, and the term "concentricity" is used to indicate a factor of which the center of mass coincides with the rotational axis of the drive shaft. Likewise, the "grinding section" may include any or all of the enlarged diameter portion of the drive shaft (i.e., the large coils in the "grinding section"), a solid cone fixed to or fabricated with the drive shaft (with the front and rear coils being the same size), an at least partially hollow crown fixed to or fabricated with the drive shaft (with the front and rear coils being the same size), or coils of different sizes plus a cone or crown fixed to or fabricated with the drive shaft. In this manner, the terms "concentric"/"eccentric" and "grinding section" are generally used to describe various configurations of the rotational atherectomy device.

Herein, the term "component" may be used to refer to any feature associated with a drive shaft, such as a grinding cone, mass, weight, counterweight, change in size and/or shape of a drive shaft coil, or any other component that distinguishes a typical featureless drive shaft.

Typically, the drive shaft may include at least one helically curved coil surrounding the wire such that the wire may be translated longitudinally relative to the drive shaft. In other words, the lead may be longitudinally advanced and retracted relative to the drive shaft, and/or the drive shaft may be longitudinally advanced and retracted relative to the lead. Advancement and/or retraction may be performed at any suitable time before, during, and/or after clearing the stenosis.

When the rotational atherectomy device comprises only a single component, such as a single grinding cone, or a single section of the drive shaft with an enlarged coil, it will be unstable during operation. For example, when the single component is rotated rapidly about the rotational axis of the drive shaft, the single component will be highly susceptible to deflection, resulting in erratic orbital movement of the component and possible damage to the interior of the vessel being cleaned.

To enhance stability, one possible approach is to increase the mass of only a single component. This added mass may provide enhanced resistance to yaw, but if the component is eccentric (its centre of mass is offset from the axis of rotation of the drive shaft), the addition of mass may reduce the stability of the orbital motion itself simply because the mass outside the shaft is excessive. This increase in eccentric mass can lead to damage to the drive shaft which rotates in unison.

An improvement that does not simply add mass to a single component is to provide the component with one or more counterweights that are longitudinally offset from the component along the drive shaft. The increase in mass as a whole does improve stability during operation, but if the proximal or distal added mass is associated with a single component, stability can be improved without disturbing the orbital motion of the single component.

In some cases, the increase in mass may be a proximal counterweight and a distal counterweight, the counterweights being distributed longitudinally along the drive shaft on either side of the abrasive member. The following paragraphs will describe various structures for these weights.

In some cases, the abrasive member may be located midway between the proximal and distal counterweights. In other examples, the abrasive member may be closer to one weight than another weight.

In some cases, the proximal and distal counterweights may have equal masses. In some cases, both the proximal and distal counterweights may have a mass equal to half of the abrasive member. In some cases, both the proximal and distal counterweights may have a mass equal to half that of the abrasive members, and the abrasive members may be longitudinally centered between the counterweights.

In some cases, the abrasive member may be eccentric. In some cases, the abrasive component may be eccentric and both counterweights are eccentric. In other examples, the abrasive component may be eccentric, with one weight being eccentric and the other weight being concentric. In some such examples, the combined center of mass of the counterweight and abrasive element coincides with the rotational axis of the drive shaft. In other such examples, the combined center of mass of the counterweight and abrasive element is offset from the rotational axis of the drive shaft.

In some cases, the abrasive members may be concentric. In some cases, the abrasive components may be concentric and both weights concentric. In other examples, the abrasive elements may be concentric, with both counterweights being concentric but on opposite sides of the drive shaft, such that their combined center of mass generally coincides with the axis of rotation of the drive shaft. In other examples, the abrasive elements may be concentric, with both counterweights being concentric but on the same side of the drive shaft, such that their combined center of mass is generally offset from the rotational axis of the drive shaft.

In some cases, there may be more than one proximal counterweight, and/or more than one distal counterweight. In some cases, adjacent counterweights may be off-center, distributed on opposite sides of the drive shaft, such that their combined center of mass is approximately coincident with the axis of rotation of the drive shaft.

In some cases, the shape of the at least one weight may be generally circular, having a substantially smooth outer surface. This helps to reduce any unwanted damage to the interior of the vessel during use.

In some cases, the guide wire may still extend through the interior of the drive shaft during use, and may even protrude out of the end of the drive shaft or beyond. This improves the overall stability of the atherectomy device, as the local stiffness of the wire may be greater than that of the drive shaft, but may reduce the amplitude of any eccentric component orbital motion of the drive shaft. In this case, however, the wire is subjected to an undesirable bending stress.

In other examples, the guidewire may be partially or fully retracted from the distal end of the drive shaft prior to use. Without the local stiff wire, the drive shaft may flex more freely when rotated under centrifugal force than if it were a wire. Thus, for a given rotational speed and size of the part, at high speed of rotation, the eccentric part through which no wire passes may extend away from the axis of rotation and thus produce a satisfactorily larger cutting diameter. The increase in cut diameter may be by a factor of four or more, depending on the hardness, tortuosity and/or flexibility associated with the material.

It may be more advantageous for the wire to be retracted in several ways. For example, if a design goal is to achieve a particular cutting diameter at a given rotational speed, the resting diameter of the eccentric abrading element may be reduced if the wire is retracted, as compared to retaining the wire through the drive shaft during use. In other words, if the wire is retracted before use (or in use), the smaller abrasive member can achieve the desired cutting diameter under otherwise identical conditions. The advantage of a smaller abrasive component is that it is easier to insert such a smaller component through a patient's vasculature, less likely to occlude, easier to manipulate, and may reduce unnecessary damage to the vessel before and after use.

Furthermore, upon retraction, the guidewire will be subjected to bending stresses and thus less susceptible to damage, which further reduces the risk of damage to the cleared vessel.

In some cases, the guidewire extends to the distal end of the drive shaft, or beyond the distal end, during use. In some cases, the wire may be retracted into the end weight prior to use, or during use. In some cases, the wire may be retracted into the abrasive member prior to use, or during use. In some cases, the guidewire may be retracted into the proximal counterweight prior to use, or during use. In some cases, the lead may be retracted beyond the proximal counterweight prior to use, or during use.

Fig. 10-17 are cross-sectional schematic views of portions of the drive shaft 120 including abrasive members 121C, 121E with an abrasive portion 122 coated thereon, and end weights 124C, 124E. The rotation shaft 125 extends through the center of the driving shaft 120. For simplicity, the single coil of drive shaft 120 is not shown. The components 121C, 121E, 123C, 123E, 124C, and 124E are shown as circles only in the figures, but it should be noted that any or all of the components may be grinding cones, masses, weights, counterweights, changes in the size and/or shape of the drive shaft coil, or any other feature that may be distinguished from a conventional featureless drive shaft 120.

Fig. 10 shows eccentric abrasive element 121E, eccentric proximal counterweight 123E, and eccentric distal counterweight 124E. Fig. 11 shows eccentric abrasive element 121E, eccentric proximal counterweight 123E, and concentric distal counterweight 124C. Fig. 12 shows eccentric abrasive element 121E, eccentric proximal counterweight 123E, and concentric distal counterweight 124E. Fig. 13 shows eccentric abrasive element 121E, eccentric proximal counterweight 123C and concentric distal counterweight 124C. Fig. 14 shows concentric abrasive member 121C, eccentric proximal counterweight 123E and eccentric distal counterweight 124E. Fig. 15 shows a concentric abrasive member 121C, an eccentric proximal counterweight 123E and a concentric distal counterweight 124C. Fig. 16 shows a concentric abrasive member 121C, concentric proximal counterweight 123C, and eccentric distal counterweight 124E. Fig. 17 shows a concentric abrasive member 121C, concentric proximal counterweight 123C and concentric distal counterweight 124C.

Fig. 18 is a schematic view of the abrasive member 121 and the counterweights 123 and 124, with a distance D1 between the centers of mass of the proximal counterweight 123 and the abrasive member 121 and a distance D2 between the centers of mass of the distal counterweight 124 and the abrasive member 121. In some cases, D1 is equal to D2. In other cases, D1 is different from D2. Note that D1 and D2 shown in fig. 18 are distances between the centroids of the components; alternatively, D1 and D2 may represent the longitudinal distance along the rotational axis of the drive shaft.

In some cases, the distances D1 and D2 are controllable and/or adjustable. For example, a counterweight that is manufactured separately from the drive shaft and then secured to the drive shaft (as opposed to being co-manufactured with the drive shaft) may also be unlocked, slid along the drive shaft to a new position, thereby creating a new D1 and/or D2, and locked in the new position of the drive shaft. The sliding may be mechanically initiated, such as by a slide wire that may slide parallel to, but independent of, the wire. Such a trolley may be connected to and parallel to the wire, or may be concentric with the wire, either inside the wire or outside the wire. Alternatively, the sliding may be magnetically activated, such as by a magnet or magnetic member attracting or repelling the weight. The locking mechanism may use clamps, clamps/collets, or other known methods of locking one component to another so that the components are slidably locked to the drive shaft. Preferably, the unlocking, sliding and locking are performed when the intraluminal plaque device is not being used to clear a stenosis; this operation should be performed at a relatively low rotational speed or when the device is not operating.

Fig. 19-23 show the lead 136 extending through the drive shaft 130 during and/or prior to use.

Note that in this series of figures, the abrasive member and counterweight are all eccentric and are comprised of an enlarged portion of the drive shaft, as shown in fig. 19-23. The enlarged portion of the drive shaft may include enlargement on only one side of the drive shaft, or both sides of the drive shaft. Any or all of the expansions may be asymmetric in that the center of mass of the expansion may be laterally offset from the axis of rotation of the drive shaft; this is the case for the exemplary eccentric member shown in fig. 19-23. Alternatively, any or all of the enlargements may be symmetrical about the rotational axis of the drive shaft such that the respective components are concentric.

It should be recognized that for all examples of the present application, the enlarged portion of the drive shaft is interchangeable with or a component attached to the drive shaft. With respect to fig. 19-23, we choose to draw a larger portion of the drive shaft, although an attachment member may also be used.

Fig. 19 shows the guidewire 136 extending beyond the distal end 130 of the drive shaft during operation. Fig. 20 shows the wire 136 retracted to the end weight 134 during or prior to operation. Fig. 21 shows the wire 136 retracted to the abrasive member 131 during or prior to operation. Fig. 22 shows the lead 136 retracted to the proximal counterweight 133 during or prior to operation. Fig. 23 shows the guidewire 136 retracted beyond the proximal counterweight 133 during or prior to operation.

In fig. 19-23, the abrasive section 132 comprises an abrasive tape that extends over the entire drive shaft. Alternatively, the abrasive section may extend across only a portion of the drive shaft, with no abrasive material on the relatively flat side.

The description of the invention and its examples disclosed herein are illustrative and are not intended to limit the scope of the invention. Variations and modifications to the embodiments disclosed herein are possible, and practical substitutions of the embodiments to equivalents of the various parts will also be apparent to those skilled in the art after studying this patent document. These and other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.

Claims (7)

1. A high-speed rotational atherectomy device for opening a stenosis in a given artery, comprising:

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

a flexible, elongated, advanceable and rotatable drive shaft along the guidewire;

an eccentric abrasive member disposed on the drive shaft;

a proximal counterweight attached to the drive shaft and gradually spaced closer to the eccentric abrasive element by an adjustable proximal spacing; and

an end weight attached to the drive shaft and gradually spaced away from the eccentric abrasive element by an adjustable end spacing,

the method is characterized in that:

wherein the proximal and distal counterweights are held in place by a locking mechanism, and

wherein the adjustable proximal and distal spacing from the eccentric abrasive element is achieved by unlocking the locking mechanism and sliding the proximal and distal counterweights along the drive shaft, and

the locking mechanism is then locked when proximal and distal spacing is achieved.

2. The high-speed rotational atherectomy device of claim 1, wherein the locking mechanism comprises a clamp, wherein the proximal counterweight is movably secured to the drive shaft, wherein the proximal counterweight is secured to the drive shaft at an adjustable proximal spacing from the eccentric abrasive section to rotate the drive shaft at a high speed, and wherein the proximal counterweight is unlockable for adjustment of the proximal spacing, the adjustment being performed when the drive shaft is rotating at a low speed or not.

3. The high-speed rotational atherectomy device of claim 2, wherein the proximal counterweight is slidable along the drive shaft when the proximal counterweight is unlocked.

4. The high-speed rotational atherectomy device of claim 1, wherein the locking mechanism comprises a clamp, wherein the distal counterweight is movably secured to the drive shaft, wherein the distal counterweight is secured to the drive shaft for rotating the drive shaft at a high speed, and wherein the distal counterweight is unlockable for adjusting the spacing of the distal ends, the adjusting being performed when the drive shaft is rotating at a low speed or not rotating.

5. The high-speed rotational atherectomy device of claim 4, wherein the tip weight is slidable along the drive shaft when the tip weight is unlocked.

6. The high-speed rotational atherectomy device of claim 1, wherein the eccentric abrading element comprises an eccentric abrading crown attached to the drive shaft.

7. The high-speed rotational atherectomy device of claim 1, wherein the eccentric abrasive section comprises an eccentric enlarged section of the drive shaft.