HK1144243A - Eccentric abrading head for high-speed rotational atherectomy devices - Google Patents

Description

Eccentric abrading head for high speed rotational atherectomy devices

Inventor(s):

R.J. Sa cut, American citizen, Blaine, Minn.

P.j. robinson, american citizen, motometidi (Mahtomedi) living in minnesota.

Background

Technical Field

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

Background

Various techniques and instruments have been developed for removing or repairing tissue within arteries and similar body passageways. A common goal of such techniques and instruments is to remove atherosclerotic plaque from within a patient's artery. Atherosclerosis is characterized by the formation of fatty deposits (atheromas) in the intimal layer (under the endothelium) of the patient's blood vessels. Over time, the initially precipitated relatively soft cholesterol-rich atherosclerotic material tends to harden into calcified atherosclerotic plaques. Such atheroma restricts blood flow and is therefore commonly referred to as a stenotic lesion or stenosis of a blood vessel, and the material of the obstruction is referred to as a narrowing material. Such vascular stenosis can lead to angina, hypertension, myocardial infarction, stroke, etc., if left untreated.

Rotational atherectomy has become a common technique for removing such narrowed material. Such procedures are most often used to open an opening of a calcified lesion in a coronary artery. Most commonly, such rotational atherectomy procedures are not used alone, but rather are performed after balloon angioplasty, which is usually followed by placement of a stent to help maintain the patency of the artery being dilated. For non-calcific lesions, balloon angioplasty alone is typically used to open the artery, and a stent is also typically placed to maintain the patency of the opened artery. However, studies have shown that most patients who have undergone balloon angioplasty and have a stent placed in an artery experience restenosis of the stent, i.e., over time, often an occlusion of the stent is formed due to overgrowth of scar tissue within the stent. In such cases, atherectomy is the preferred surgical procedure for removing excess scar tissue from the stent (balloon angioplasty is not or is not very effective within the stent), whereby opening of the artery can be restored.

To remove stenotic material, several types of rotational atherectomy devices have been developed. In one type of device, such as that shown in U.S. Pat. No.4,990,134 (to Auth), barbs coated with an abrasive grinding material, such as diamond particles, are mounted on the end of a flexible drive shaft. The barbs are rotated at high speeds (typically, for example, in the range of about 150,000-. However, when the bur removes stenotic tissue, it also occludes blood flow. Once the prickle has been advanced across the stenosis, the artery will be opened to a diameter equal to or only slightly greater than the maximum outer diameter of the prickle. It is often necessary to have more than one gauge of barbs to open the artery to the desired diameter.

U.S. patent No.5,314,438 to Shturman discloses another atherectomy device having a drive shaft with a portion of the drive shaft having an enlarged diameter, at least a segment of the enlarged surface being coated with abrasive material to form an abrasive segment of the drive shaft. The abrasive segment is capable of removing stenotic tissue from the artery when it is rotated at high speed. Although this atherectomy device has advantages over the Auth device due to its flexibility, it can only open the artery to a diameter approximately equal to the diameter of the enlarged abrasive surface of the drive shaft, since the nature of the device is not eccentric.

U.S. patent No.6,494,890 to Shturman discloses a drive shaft having an enlarged eccentric portion wherein at least a segment of the enlarged portion is coated with abrasive material. The abrasive segment is capable of removing stenotic tissue from the artery when it is rotated at high speed. The device is capable of opening the diameter of the artery to be greater than the resting diameter of the enlarged eccentric portion, in part because of its orbital rotational movement during high speed rotation. Because the enlarged eccentric portion includes the drive shaft wire that is not bonded together, the enlarged eccentric portion of the drive shaft may bend during placement in the stricture or during high speed operation. This curvature may allow for a larger diameter opening to be performed during high speed operation, but also provides less control over the actual diameter of the artery being abraded than desired. In addition, some stenotic tissue may completely block the channel, such that the Shturman device cannot be placed through the channel. Since Shturman requires that the enlarged eccentric portion of the drive shaft be placed within the stenotic tissue to achieve abrasion, it is no longer effective in preventing the enlarged eccentric portion from moving into the stenotic site. U.S. Pat. No.6,494,890 is incorporated herein by reference in its entirety.

U.S. patent No.5,681,336 (issued to Clement) provides an eccentric tissue-removing burr having a coating of abrasive particles secured to a portion of the outer surface of the burr by a suitable bonding material. However, because the asymmetric barbs rotate at a "lower speed than the speed used by the high speed cutting device to compensate for heat or imbalance" as explained by Clement in column 3, lines 53-55. That is, given the size and mass of a solid barb, it is not feasible to rotate the barb at the high speeds used during atherectomy, i.e., 20,000-. Fundamentally, a deviation from the center of mass of the axis of rotation of the drive shaft results in the formation of large centrifugal forces which exert excessive pressure on the artery wall and create excessive heat and particles.

The present invention overcomes these deficiencies.

Disclosure of Invention

The present invention provides a rotational atherectomy device which, in various embodiments, has a flexible, elongated, rotatable drive shaft to which is attached at least one flexible, eccentric, enlarged abrading head. In other embodiments, the eccentric grinding head is not flexible or partially flexible. At least a portion of the eccentrically enlarged abrading head has a tissue removing surface, which is typically an abrasive surface. In certain embodiments, the grinding head is at least partially hollow. When the abrading head is placed in an artery against stenotic tissue and rotated at a sufficiently high speed, the eccentric nature of the enlarged cutting head causes the cutting head and drive shaft to rotate in the following manner: it opens the stenotic lesion to a diameter significantly greater than the outer diameter of the enlarged grinding head. Preferably, the eccentric enlarged grinding head has a center of mass spaced radially from the axis of rotation of the drive shaft to enable the device to open a stenotic lesion to a diameter substantially greater than the outer diameter of the enlarged grinding head when operated at high speeds.

It is an object of the present invention to provide a high speed rotational atherectomy device having at least one flexible, eccentric cutting head with a resting diameter that is smaller than the diameter of the cutting head when it is rotated at high speeds.

It is another object of the present invention to provide a high speed rotational atherectomy device having at least one non-flexible eccentric cutting head with a resting diameter that is smaller than its diameter at high speed rotation.

It is another object of the present invention to provide a high-speed rotational atherectomy device having at least one flexible, eccentric cutting head that is capable of opening a pilot hole in a stenotic site that almost or completely obstructs a patient's blood vessel.

It is another object of the present invention to provide a high-speed rotational atherectomy device having at least one non-flexible eccentric cutting head that is capable of opening a pilot hole in a stenotic site that almost or completely obstructs a patient's blood vessel.

It is another object of the present invention to provide a high speed rotational atherectomy device having at least one flexible, eccentric cutting head that can flex during insertion and placement of the cutting head to enhance the ability to cope with tortuous lumens with minimal trauma.

It is another object of the present invention to provide a high speed rotational atherectomy device having at least one non-flexible eccentric cutting head, the cutting head not bending during operation, providing the operator with a better degree of control over the diameter of the cutting head track.

The figures and the detailed description that follow more particularly exemplify 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 one embodiment of a non-flexible eccentric cutting head of the rotational atherectomy device of the present invention;

FIG. 2 is a cut-away perspective view of a prior art flexible eccentric cutting head formed by a drive shaft;

FIG. 3 is a broken-away longitudinal cross-sectional view of a prior art eccentric cutting head formed by a drive shaft;

FIG. 4 is a longitudinal cross-sectional view taken in section showing the flexibility of the prior art flexible eccentric enlarged cutting head formed by the drive shaft;

FIG. 5 is a longitudinal cross-sectional view of a prior art solid eccentric grinding burr attached to a drive shaft;

FIG. 6 is a longitudinal cross-sectional view in section showing the geometry of one embodiment of the non-flexible eccentric cutting head of the rotational atherectomy device of the present invention;

fig. 7A is a perspective view of one embodiment of the non-flexible eccentric cutting head of the present invention;

fig. 7B is a bottom view of one embodiment of the non-flexible eccentric cutting head of the present invention;

fig. 7C is a longitudinal cross-sectional view of one embodiment of the non-flexible eccentric cutting head of the present invention;

FIGS. 8A-8C are transverse cross-sectional views of one embodiment of a non-flexible eccentric cutting head of the present invention;

fig. 9A is a perspective view of one embodiment of the non-flexible eccentric cutting head of the present invention;

fig. 9B is a bottom view of an embodiment of the non-flexible eccentric cutting head of the present invention;

fig. 9C is a longitudinal cross-sectional view of one embodiment of the non-flexible eccentric cutting head of the present invention;

fig. 10A is a perspective view of one embodiment of the non-flexible eccentric cutting head of the present invention;

fig. 10B is a bottom view of an embodiment of the non-flexible eccentric cutting head of the present invention;

fig. 10C is a longitudinal cross-sectional view of one embodiment of the non-flexible eccentric cutting head of the present invention;

FIG. 11 is a longitudinal cross-sectional view of a non-flexible eccentric cutting head of the atherectomy device of the present invention, shown just prior to use to remove stenotic tissue from an artery;

FIG. 12 is a longitudinal cross-sectional view of the non-flexible eccentric enlarged cutting head of the present invention in a rest (non-rotating) position after the stricture has been substantially opened by the device of the present invention;

FIG. 13 is a transverse cross-sectional view showing three different positions of a rapidly rotating non-flexible eccentric enlarged cutting head of the eccentric rotational atherectomy device of the present invention;

FIG. 14 is a schematic illustration of three positions of a non-flexible eccentric enlarged cutting head corresponding to the rapid rotation shown in FIG. 13;

FIG. 15 is a perspective view of one embodiment of the present invention with flexible slots integrally formed therein;

FIG. 16 is a side view of one embodiment of the present invention with flexible slots integrally formed therein;

FIG. 17 is a perspective view of one embodiment of the present invention with flexible slots integrally formed therein;

FIG. 18 is a perspective view of one embodiment of the present invention with a flexible slot integrally formed therein.

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 understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Figure 1 illustrates one embodiment of a rotational atherectomy device according to the present invention. The device includes a handle portion 10, an elongated flexible drive shaft 20 having an eccentric enlarged grinding head 28, and an elongated conduit 13 extending distally from the handle portion 10. The drive shaft 20 is constructed from a helical coil wire as is well known in the art, and the grinding head 28 is fixedly attached to the drive shaft. The catheter 13 has a lumen in which the majority of the length of the drive shaft 20 is disposed, except for the enlarged grinding head 28 and a short segment at the distal end of the enlarged grinding head 28. The drive shaft 20 also contains a lumen that allows the drive shaft 20 to advance and rotate over the guidewire 15. A fluid supply line 17 may be provided to introduce a cooling and lubricating solution (typically saline or other biocompatible fluid) into the conduit 13.

The handle portion 10 preferably contains a turbine (or similar rotational drive mechanism) for rotating the drive shaft 20 at high speed. The handle portion 10 is typically connectable to a power source, such as compressed air supplied through a tube 16. A pair of fiber optic cables 25 (or a single cable may be used) may also be provided to monitor the rotational speed of the turbine and drive shaft 20 (details regarding such handles and related instrumentation are well known in the art, such as described in U.S. patent No.5,314,407 to Auth). The handle portion 10 also desirably includes a control knob 11 that advances and retracts the worm gear and drive shaft 20 relative to the catheter 13 and handle body.

Figures 2-4 show details of a prior art device including an eccentric enlarged diameter grinding section 28A of drive shaft 20A. The drive shaft 20A includes one or more helically wound wires 18 that form a guidewire lumen 19A and a hollow lumen 25A within the enlarged abrading portion 28A. The hollow cavity 25A is substantially empty, except that the guidewire 15 traverses the hollow cavity 25A. Eccentric enlarged diameter abrading segment 28A includes, in sequence relative to the stenosis of the organ, a proximal segment 30A, an intermediate segment 35A and a distal segment 40A. The turns 31 of the proximal portion 30A of the eccentric enlarged diameter grinding portion 28A preferably have diameters that gradually increase distally at a generally constant rate, thereby forming a generally conical shape. The turns 41 of the distal portion 40A preferably have diameters that gradually decrease toward the distal end at a substantially constant rate, thereby forming a substantially conical shape. Turns 36 of intermediate portion 35A are provided with a gradually changing diameter to provide a generally convex outer surface shaped to provide a smooth transition between the proximal and distal tapered portions of eccentric enlarged diameter grinding portion 28A of drive shaft 20A.

With continued reference to the prior art devices, at least a portion of the eccentric enlarged diameter grinding section 28A of the drive shaft, preferably the intermediate section 35A, includes an outer surface capable of removing tissue. A tissue-removing surface 37 comprising a coating of abrasive material 24A to form a tissue-removing segment of the drive shaft 20A is shown with the tissue-removing surface 37 attached directly to the turns of the drive shaft 20A by a suitable adhesive 26A.

Figure 4 illustrates the flexibility of the eccentric enlarged diameter grinding portion 28A of the prior art drive shaft, which is shown as the drive shaft 20A may be advanced over the guide wire 15. In the illustrated embodiment, adjacent turns of the central portion 35A of the eccentric enlarged grinding head of the drive shaft are secured to one another by a bonding material 26A that secures the abrasive particles 24A to the turns 36. The proximal and distal portions 30A and 40A of the eccentric enlarged diameter ground portion of the drive shaft, which include turns 31 and 41, respectively, are not secured to one another, thereby allowing these portions of the drive shaft to flex, as shown. Such flexibility facilitates advancement of the device through relatively tortuous paths. However, adjacent turns 36 of intermediate portion 35A of eccentric enlarged diameter ground portion 28A of the drive shaft are secured to one another, thereby limiting the flexibility of ground portion 28A.

Figure 5 illustrates another prior art rotational atherectomy device which uses a solid asymmetrical abrading burr 28B attached to a flexible drive shaft 20B and which may be rotated over a guide wire 15 as provided in U.S. patent No.5,681,336 to Clement. The eccentric debulked barbs 28B have a coating of abrasive particles 24B, which are secured to the outer surface of a portion of the abrasive particles 24B by a suitable bonding material 26B. However, this configuration limits its efficacy because the asymmetrical barbs 28B must rotate at a "lower rotational speed than that used in high speed grinders to compensate for heat or unbalanced rotational speed" as explained by Clement in column 3, lines 53-55. That is, given the size and mass of a solid bur-type structure, it is not feasible to rotate such burs at the high speeds used in atherectomy procedures (i.e., 20,000-. Fundamentally, in this prior art device, the deviation from the center of mass of the axis of rotation of the drive shaft results in the formation of large centrifugal forces, excessive pressure on the artery wall, and the formation of too much heat, unwanted damage and excessive particles.

Turning now to fig. 6, 7A-7C, and 8A-8C, one embodiment of the non-flexible, eccentric enlarged abrading head 28 of the rotational atherectomy device of the present invention will be discussed.

The drive shaft 20 has an axis of rotation 21 coaxial with the guide wire 15, the guide wire 15 being disposed within the lumen 19 of the drive shaft 20. Referring particularly to fig. 6 and 7A-7C, the proximal portion 30 of the eccentric enlarged grinding head 28 has an outer surface substantially defined by the side surfaces of a truncated cone whose axis 32 intersects the rotational axis 21 of the drive shaft 20 at a relatively small angle β. Similarly, the distal portion 40 of the eccentric enlarged grinding head 28 has an outer surface substantially defined by the side surfaces of a truncated cone whose axis 42 also intersects the rotational axis 21 of the drive shaft 20 at a relatively small angle β. The cone axis 32 of the proximal portion 30 and the cone axis 42 of the distal portion 40 intersect each other and are coplanar with the longitudinal axis of rotation 21 of the drive shaft.

The angle α of the opposite sides of the cone should generally be between about 10 ° and 30 °, preferably between about 20 ° and 24 °, and most preferably about 22 °. Also, the cone axis 32 of the proximal portion 30 and the cone axis 42 of the distal portion 40 generally intersect the axis of rotation 21 of the drive shaft 20 at an angle β between about 20 ° and 8 °. Preferably the angle beta is between about 3 deg. and 6 deg.. Although in the preferred embodiment shown in the drawings, the angles α of the distal and proximal portions of the enlarged grinding head 28 are substantially equal, these angles need not be equal. The same applies to the angle β.

In an alternative embodiment, intermediate portion 35 may include a diameter that gradually increases from the intersection with distal portion 40 toward the intersection with proximal portion 30. In this embodiment, the angle α as shown in fig. 6 may be greater in the proximal portion 30 than in the distal portion 40, or vice versa. Other alternative embodiments include an intermediate portion 35 having a convex surface, wherein the outer surface of the intermediate portion may be shaped such that a smooth transition is formed between the proximal and distal outer surfaces of the proximal and distal portions.

The abrading head 28 may include at least one tissue removal surface 37 on the outer surface of the intermediate portion 35, distal portion 40, and/or proximal portion 30 to facilitate abrading away stenotic portions during high speed rotation. Tissue removal surface 37 may include a coating of abrasive material 24, with abrasive material 24 bonded to the outer surface of intermediate portion 35, distal portion 40, and/or proximal portion 30 of grinding head 28. 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 comprised of diamond grains (or diamond powder particles) and is directly attached to the tissue removal surface by a suitable adhesive 26, such attachment being accomplished using well known techniques, such as conventional electroplating or fusing techniques (see, for example, U.S. Pat. No.4,018,576). Alternatively, the outer tissue removal surface may include mechanically or chemically roughening the outer surface of intermediate section 35, distal section 40, and/or proximal section 30 to provide a suitable abrasive tissue removal surface 37. In yet another variation, the outer surface may be etched or cut (e.g., with a laser) to provide a small and effective grinding surface. Other similar techniques may also be used to provide a suitable tissue removal surface 37.

As best shown in fig. 7A-7C, an at least partially enclosed cavity or slot 23 may be provided through the enlarged grinding head 28 longitudinally along the rotational axis 21 of the drive shaft 20 to secure the enlarged grinding head 28 to the drive shaft 20 in a manner well known to those skilled in the art. In the illustrated embodiment, a hollow portion 25 is provided to reduce the mass of the grinding head 28 to facilitate damage-free grinding and to improve predictability of orbital path control of the grinding head 28 during high speed operation, i.e., 20,000 to 200,000rpm operation. In this embodiment, the grinding head 28 may be fixedly attached to the drive shaft 20, wherein the drive shaft comprises a single unit. Alternatively, as discussed below, the drive shaft 20 may comprise two separate components, wherein the eccentric enlarged grinding head 28 is fixedly attached to the two components of the drive shaft 20 with a gap remaining therebetween. This two-piece drive shaft construction technique, in combination with the hollow portion 25, may allow for further manipulation of the placement of the center of mass of the grinding head 28. The size and shape of the hollow portion 25 may be modified to optimize the orbital path of rotation of the grinding head 28 for a particular desired rotational speed. Those skilled in the art will readily recognize the various possible configurations that are within the scope of the present invention. The embodiment of fig. 6, 7A-7C shows proximal portion 30 and distal portion 40 having symmetrical shapes and lengths. Alternative embodiments may increase the length of either proximal portion 30 or distal portion 40 to create an asymmetric profile.

Because the cone axes 32 and 42 intersect the rotational axis 21 of the drive shaft 20 at an angle β, the eccentric enlarged grinding head 28 has a center of mass that is radially away from the longitudinal rotational axis 21 of the drive shaft 20. As will be described in greater detail below, the offset of the center of mass from the drive shaft axis of rotation 21 provides for the enlarged grinding head 28 to have an eccentricity that allows the grinding head to open the artery to a diameter that is significantly greater than the nominal diameter of the eccentric enlarged grinding head 28, preferably at least twice the nominal resting diameter of the eccentric enlarged grinding head 28.

Fig. 8A-8C illustrate the location of the center of mass 29 of the three sections (shown as surfaces of transverse sections) of the eccentric enlarged grinding head 28 shown in fig. 6 and 7A-7C, wherein the eccentric enlarged grinding head 28 is fixedly attached to the drive shaft 20, and the drive shaft 20 is advanced over the guide wire 15, and the guide wire 15 is located within the drive shaft lumen 19. The entire eccentric enlarged grinding head 28 may be divided into a number of lamellae, each having its own center of mass. Fig. 8B is taken from the location where the eccentric enlarged grinding head 28 has its largest cross-sectional diameter (which in this embodiment is the largest diameter of the intermediate portion 35 of the eccentric enlarged grinding head 28), while fig. 8A and 8C are cross-sections of the distal portion 40 and the proximal portion 30, respectively, of the eccentric enlarged grinding head 28. In each of these cross-sectional slices, the center of mass 29 is remote from the axis of rotation 21 of the drive shaft 20, the axis of rotation of the drive shaft 20 coinciding with the center of the guide wire 15. The center of mass 29 of each cross-sectional slice also substantially coincides with the geometric center of such cross-sectional slice. Fig. 8B shows a cross-sectional slice of the intermediate portion 35, including the largest cross-sectional diameter of the grinding head 28, wherein the center of mass 29 and the geometric center are both located furthest from the axis of rotation 21 of the drive shaft 20 (i.e., are maximally spaced apart) as compared to the proximal portion 30 and the distal portion 40.

It should be understood that, as used herein, the term "eccentric" is defined and used to refer to an eccentric increase in the difference in position between the geometric center of the grinding head 28 and the rotational axis 21 of the drive shaft 20, or to an increase in the difference in position between the center of mass 29 of the grinding head 28 and the rotational axis 21 of the drive shaft 20. At the proper rotational speed, any such difference in position will allow the eccentric enlarged grinding head 28 to open the narrowing to a diameter significantly greater than the nominal diameter of the eccentric enlarged grinding head 28. Furthermore, for eccentric enlarged grinding heads 28 that are not regular in shape, the concept of a "geometric center" may be approximated by locating the midpoint of the longest chord drawn at two points on the perimeter of the cross-section taken through the axis of rotation 21 of the drive shaft 20 and connecting the perimeter of the eccentric enlarged grinding head 28 at the location where it has its greatest length.

The abrading head 28 of the rotational atherectomy device of the present invention may be constructed of stainless steel, tungsten, or similar materials. The grinding head 28 may be of one-piece unitary construction or may be an assembly of two or more grinding head components fitted and secured together for the purposes of the present invention.

Figures 9A-9C illustrate another alternative embodiment of the non-flexible eccentric abrading head 28 of the rotational atherectomy device of the present invention. In this embodiment, as best shown in fig. 9B and 9C, a radiused transition portion 27 is provided in the transition between the drive shaft slot 23 and the hollow portion 25. In this embodiment, the drive shaft 20 is shown attached to two separate portions of the grinding head 28 with a gap remaining therebetween, while the eccentric enlarged grinding head 28 is attached to two portions of the drive shaft. Alternatively, the drive shaft 20 may be a one-piece structure as shown in FIGS. 6A-6C. This embodiment also shows a symmetrical profile, i.e., the proximal portion 30 and the distal portion 40 are shown to be of substantially equal length. As discussed above, various embodiments may include an asymmetric profile in which proximal portion 30 is longer than distal portion 40, or distal portion 40 is longer than proximal portion 30.

One embodiment of a grinding head 28 of the present invention having an asymmetrical profile is shown in fig. 10A-10C. In this embodiment, the length of proximal portion 30 is greater than the length of distal portion 40. As a result, referring back to the geometry of FIG. 6, in the embodiment shown in FIGS. 10A-10C, the angle α of proximal portion 30 is less than the angle α of distal portion 40. This particular geometry may be advantageous, for example, when the abrading head 28 reaches a partially occluded or fully occluded artery that prevents the passage of the abrading head 28. The smaller taper of the proximal portion 30 may help to gradually grind and open the stenotic site of the occluded artery. In this manner, a pilot hole may be formed and then gradually enlarged so that the entire grinding head 28 may be advanced through the stenosis.

Those skilled in the art will recognize that the embodiments shown herein, including particularly those shown in fig. 7A-7C, 9A-9C, and 10A-C, may include at least one tissue-removing surface 37 as described above. Tissue removal surface 37 may be disposed on one or more of intermediate portion 35, proximal portion 30, and/or distal portion 40 of eccentric abrading head 28.

In fig. 11, eccentric enlarged grinding head 28 is advanced over guidewire 15 through drive shaft lumen 19 to a position in artery "a" just proximal to the stenosis having a diameter (defined by plaque "P") less than the nominal maximum resting diameter of eccentric enlarged grinding head 28 of drive shaft 20. As discussed above, the distal portion 40 of the grinding head 28 forms a cone with a reduced radius tip. This facilitates the access of the grinding head 28 into the stenosed site even in the stationary configuration.

However, the illustrated embodiment of the present abrading head 28 is not flexible and thus resists deformation, and as a result, unlike prior art devices, the present abrading head cannot be forced through such stenotic sites when the atherectomy device is stationary. Thus, this embodiment of the grinding head 28 of the present invention must grind its path through the narrow region.

In some cases, including those presently discussed, the use of an increased diameter of the distal portion 40 of the grinding head 28 to increase the diameter of the opening, the grinding head 28 may be used to create the opening gradually and atraumatically until sufficient plaque is removed to allow the grinding head 28 to advance through and across the stenosis and then withdraw. There are several features that enhance the ability to form the pilot hole. The tapered proximal portion 30 allows for gradual advancement and controlled abrasion of the tissue removal surface 37 into the stricture, creating a pilot hole for continued advancement of the abrading head 28. In addition, the intersection of the tapered proximal portion 30 of the grinding head 28 (and the distal portion 40, not shown) with the cylindrical intermediate portion 35 may form an edge that cuts or grinds away plaque as the device is progressively advanced, thus increasing the diameter of the stricture being ground. In addition, as discussed above, the surfaces of proximal portion 30 and intermediate and distal portions 35, 40 (not shown) of grinding head 28 may be covered, in whole or in part, by the abrasive material of tissue-removing surface 37, thereby facilitating the gradual and controlled grinding of plaque and opening of the stenosis during advancement and retraction of the grinding head through the stenosis. Eventually, enough plaque will be removed to allow the entire abrading head 28 to be advanced across the stenosis and withdrawn.

Thus, as the drive shaft 20 is advanced and withdrawn to continuously move the eccentric enlarged grinding head 28 across the stenosis, the rotating eccentric enlarged grinding head 28 will continue to remove plaque "P" from the artery "A" and open the diameter of the stenosis to a diameter substantially greater than the nominal diameter of the enlarged grinding head 28. Because the present grinding head may have ground tissue removal surfaces on distal portion 40, intermediate portion 35, and/or proximal portion 30, grinding plaque and opening stenoses may occur during advancement and retraction.

In addition, the non-flexible grinding head 28 may be sized to form a pilot hole through a narrow site, essentially creating a passageway for the successively larger grinding heads 28 of the present invention to progressively open the opening, or the passageway may be created by some prior art means such as those described by Shturman in 6,494,890, i.e., by a flexible eccentric enlarged portion of the drive shaft. Such a configuration may include the use of two separate devices, or the combination of two (or more) devices within a single device. For example, it may be advantageous to place the non-flexible eccentric abrading head 28 of the present invention distally along the drive shaft 20 in combination with placing the flexible eccentric enlarged abrading portion of the drive shaft 20 more proximally as described in' 890 of Shturman. In this embodiment, a pilot hole may be opened using the non-flexible grinding head 28 so that the flexible eccentric enlarged grinding portion of the drive shaft 20 may follow through the narrowed portion to open further. Alternatively, successively larger non-flexible grinding heads 28 may be arranged in series along the drive shaft 20, with the smallest being placed most distally, i.e., closest to the stenosis, along the drive shaft 20. Still more alternatively, a combination of non-flexible and flexible (discussed below) eccentric grinding heads 28 may be arranged in series along the drive shaft 20.

Fig. 12 shows an enlarged eccentric abrading head 28 of the present invention with guide wire 20 and attached abrading head 28 in a "resting" position within artery "a" after advancement over guide wire 15 and substantial opening of the stricture site, thus illustrating the ability of the device to open the stricture site to a diameter exceeding the nominal diameter of the device.

The extent to which a stenotic site in an artery can be opened to a diameter greater than the nominal diameter of the eccentrically enlarged grinding head of the present invention depends on several parameters, including the shape of the eccentrically enlarged grinding head, the mass of the eccentrically enlarged grinding head, the distribution of the mass of the grinding head and thus the position of the center of mass within the grinding head relative to the rotational axis of the drive shaft, and the rotational speed.

Rotational speed is an important factor in determining the centrifugal force with which the tissue removal surface of the enlarged abrading head can be pressed against stenotic tissue, thereby allowing the operator to control the rate of tissue removal. Controlling the rotational speed also allows, to a certain extent, controlling the maximum diameter to which the device opens the stenosis. Applicants have also found that the ability to reliably control the force with which the tissue removal surface is pressed against stenotic tissue not only allows the operator to better control the rate of tissue removal, but also better control the size of the removed particles.

Fig. 13-14 illustrate the generally helical orbital path taken by various embodiments of the eccentric grinding head 28 of the present invention, showing the grinding head 28 relative to the guide wire 15 over which the grinding head 28 is advanced. The pitch of the helical path is exaggerated in fig. 13-14 for illustrative purposes, and in fact, each helical path of the eccentrically enlarged grinding head 28 removes only a very thin layer of tissue by the tissue removal surface 37, and the eccentrically enlarged grinding head 28 makes a number of such helical passes as the device is repeatedly moved back and forth across the stenosis to fully open the stenosis. Figure 14 schematically 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 grinding surface of the eccentrically enlarged grinding head 28 contacts the plaque "P" to be removed, and the three locations are represented by three distinct points of contact with the plaque "P," which are designated B1, B2, and B3. It should be noted that at each point, the same tissue contacting portion of the abrading surface, typically the eccentrically enlarged abrading head 28, is the tissue removing surface 37 which is the portion radially furthest from the rotational axis of the drive shaft.

In addition to the non-flexible embodiments of the grinding head described above, various embodiments of the present invention include some flexibility in the eccentrically enlarged grinding head 28. An exemplary embodiment is shown in fig. 15-18.

The grinding head shown in fig. 15 is similar to the grinding head provided in fig. 6, 7A-7C. Thus, with particular reference to fig. 6 and 15, the proximal portion 30 of the eccentrically enlarged grinding head 28 has an outer surface that is substantially defined by the side surface of the truncated cone discussed above in fig. 5, i.e., the cone has an axis 32 that intersects the rotational axis 21 of the drive shaft 20 at a relatively small angle β. Similarly, the distal portion 40 of the enlarged grinding head 28 has an outer surface that is substantially defined by the side surface of a truncated cone having an axis 42, the axis 42 also intersecting the rotational axis 21 of the drive shaft 20 at a relatively small angle β. The cone axis 32 of the proximal portion 30 and the cone axis 42 of the distal portion 40 intersect each other and are coplanar with the longitudinal rotational axis 21 of the drive shaft. The intermediate portion 35 is shown as a portion of a cylinder having a surface of constant diameter that is interposed between and adjacent to the tapered proximal and distal portions 30, 40. The grinding head 28 may define a substantially hollow interior with the drive shaft 20 fixedly disposed therethrough.

A flexible slot 46 is provided in the grinding head 28. The slot 46 is shown cut completely through the grinding head 28 and into the internal cavity 23 to allow maximum bending of the grinding head 28. See the side view of fig. 16. In various embodiments, the grinding head 28 bends with the flexible drive shaft 20 to facilitate coping with tortuous passageways within the patient's lumen. Such flexibility within the grinding head 28 may therefore provide less traumatic entry en route to the lesion to be ground, and less trauma upon exit therefrom. Providing such flexibility requires at least one flexible slot 46; preferably, a plurality of flexible slots 46 are provided.

The embodiment of the flexible grinding head 28 of fig. 15 shows a series of uniformly arranged flexible slots 46 of substantially uniform width and depth, wherein the slots 46 cut completely through the grinding head 28 into the internal cavity 23 therein. Those skilled in the art will recognize that the flexibility of the grinding head 28 may be controlled, i.e., modified, particularly by manipulating one or more of the following factors: the number of slots 46; the depth of the slot 46 within the grinding head 28; the width of the slot 46; the cutting angle of the slot 46; placement of the slot 46 on the grinding head 28.

Fig. 17 also illustrates the ability to use the flex slot 46 to modify or control the flex characteristics of the grinding head. In this embodiment, the flexible slot 46 is disposed at least partially through, and preferably entirely through, the wall of the grinding head 28. However, unlike the embodiment of fig. 15 and 16, this embodiment includes flexible slots 46 centered near the center of the grinding head 28, i.e., disposed within the intermediate portion 35, with only one slot 46 engaging the proximal end portion 30 and only one slot 46 engaging the distal end portion 40. It will be apparent to those skilled in the art that many more equivalents are possible; each equivalent falling within the scope of the present invention.

Turning now to fig. 18, an embodiment of a half crown grinding head 28' is shown. The semi-coronal grinding head 28' embodiment includes a proximal portion 30 and an intermediate portion 35, and may be inflexible, i.e., without flexible slots 46 for stress relief. Alternatively, as shown, the half crown shaped grinding head 28' may include a stress relieving flexible slot 46 as discussed above. Furthermore, as will be appreciated by those skilled in the art, the equivalents discussed in fig. 15-17 are also applicable to the half crown grinding head 28' described herein.

Each compliant grinding head embodiment may include grinding material disposed thereon as discussed above in connection with the non-compliant embodiment.

Accordingly, the eccentric grinding head 28 of the present invention may include non-flexible and/or at least partially flexible embodiments.

While not wishing to be bound by any particular theory of operation, applicants believe that offsetting the center of mass from the axis of rotation produces an increased "orbital" motion of the grinding head, the diameter of which is controlled by varying, in particular, the rotational speed of the drive shaft. Whether this "orbital" motion is geometrically regular as shown in fig. 13-14 has not been determined, but the applicants have empirically demonstrated that by varying the rotational speed of the drive shaft, the centrifugal force urging the tissue-removing surface of the eccentrically enlarged abrading head 28 against the surface of the stricture site can be controlled. The centrifugal force may be determined according to the following formula:

F_c＝mΔx(πn/30)²

wherein, F_cIs the centrifugal force, m is the mass of the eccentrically enlarged grinding head, Δ x is the distance between the center of mass of the eccentrically enlarged grinding head and the axis of rotation of the drive shaft, and n is the rotational speed in revolutions per minute (rpm). Controlling the force F_cCan provide control over the speed of tissue removalThe device can be controlled to open the maximum diameter of the stenosis and provide increased control over the size of the tissue particles removed.

The abrading head 28 of the present invention includes more mass to remove than prior art high speed rotational atherectomy devices. As a result, a larger orbit can be achieved during high speed rotation, which in turn allows the use of a smaller grinding head than prior art devices. In addition to allowing a pilot hole to be formed in a fully or substantially occluded artery or the like, the use of a smaller abrading head may allow for more convenient access and less trauma during insertion.

In operation, using the rotational atherectomy device of the present invention, the eccentric enlarged abrading head 28 is repeatedly moved proximally and distally through the stenosis. By varying the rotational speed of the device, the operator can control the force with which the tissue removal surface is pressed against the stenotic tissue, thereby enabling better control over the speed at which plaque is removed and the particle size of the removed tissue. Since the narrowing is open to a diameter greater than the nominal diameter of the eccentric enlarged grinding head 28, coolant and blood can flow constantly around the enlarged grinding head. Once the abrading head has passed the lesion once, this constant flow of blood and coolant continually washes away the removed tissue particles, thus uniformly releasing the removed particles.

The eccentric enlarged grinding head 28 may include a maximum cross-sectional diameter ranging between about 1.0mm to about 3.0 mm. Thus, an eccentrically enlarged grinding head may include cross-sectional diameters including, but not limited to: 1.0mm, 1.25mm, 1.50mm, 1.75mm, 2.0mm, 2.25mm, 2.50mm, 2.75mm and 3.0 mm. Those skilled in the art will readily recognize that the increments of 0.25mm in the cross-sectional diameters listed above are exemplary only, and that the present invention is not limited by the exemplary list, and as a result, other incremental increments in cross-sectional diameter are possible and within the scope of the present invention.

As mentioned above, since the eccentricity of the enlarged grinding head 28 depends on a number of parameters, the applicant has found that the following design parameters can be considered with respect to the distance between the axis of rotation 21 of the drive shaft 20 and the geometric center of the cross-section taken at the location of the maximum cross-sectional diameter of the eccentric enlarged grinding head: for devices in which the eccentric enlarged grinding head has a maximum cross-sectional diameter of between about 1.0mm and about 1.5mm, the geometric center should preferably be spaced at least about 0.02mm from the axis of rotation of the drive shaft, and preferably at least about 0.035 mm; for devices in which the eccentric enlarged grinding head has a maximum cross-sectional diameter of between about 1.5mm and about 1.75mm, the geometric center should preferably be spaced from the axis of rotation of the drive shaft by a distance of at least about 0.05mm, preferably at least about 0.07mm, and most preferably at least about 0.09 mm; for devices in which the eccentric enlarged grinding head has a maximum cross-sectional diameter of between about 1.75mm and about 2.0mm, the geometric center should preferably be spaced from the axis of rotation of the drive shaft by a distance of at least about 0.1mm, preferably at least about 0.15mm, and most preferably at least about 0.2 mm; for devices in which the eccentrically enlarged grinding head has a maximum cross-sectional diameter in excess of 2.0mm, the geometric center should preferably be spaced from the axis of rotation of the drive shaft by a distance of at least about 0.15mm, preferably at least about 0.25mm, and most preferably at least about 0.3 mm.

The design parameters may also be based on the location of the center of mass. For devices in which the eccentrically enlarged grinding head 28 has a maximum cross-sectional diameter of between about 1.0mm and about 1.5mm, the center of mass should preferably be spaced from the axis of rotation of the drive shaft by a distance of at least about 0.013mm, preferably at least about 0.02 mm; for devices in which the eccentric enlarged grinding head 28 has a maximum cross-sectional diameter of between about 1.5mm and about 1.75mm, the center of mass should preferably be at least about 0.03mm, preferably at least about 0.05mm, from the axis of rotation of the drive shaft; for devices in which the eccentric enlarged grinding head has a maximum cross-sectional diameter of between about 1.75mm and about 2.0mm, the center of mass should preferably be at least about 0.06mm, preferably at least about 0.1mm, from the axis of rotation of the drive shaft; for devices in which the eccentrically enlarged grinding head has a maximum cross-sectional diameter in excess of 2.0mm, the center of mass should preferably be at least about 0.1mm, preferably at least about 0.16mm, from the axis of rotation of the drive shaft.

Preferably, for example, as shown in fig. 10C, the thickness of the wall 50 separates the hollow chamber 25 from the outer surface formed by the proximal section 30, the intermediate section 35, and/or the distal section 40, and the thickness of the wall 50 should be a minimum of 0.008 inches thick to maintain structural stability and integrity.

Preferably, the design parameters are selected such that the enlarged grinding head 28 is sufficiently eccentric such that when the grinding head is rotated over the stationary guide wire 15 (sufficiently taut to prevent any significant movement of the guide wire) at a rotational speed greater than about 20,000rpm, at least a portion of the tissue removal surface 37 of the grinding head may rotate through a path (whether such a path is perfectly regular or circular) having a diameter greater than the maximum nominal diameter of the eccentric enlarged grinding head 28. For example, and without limitation, for an enlarged grinding head 28 having a maximum diameter between about 1.5mm and about 1.75mm, at least a portion of the tissue removal surface 37 may be rotated through a path having a diameter at least about 10% greater than the maximum nominal diameter of the eccentrically enlarged grinding head 28, preferably at least about 15% greater than the maximum nominal diameter of the eccentrically enlarged grinding head 28, and most preferably at least about 20% greater than the maximum nominal diameter of the eccentrically enlarged grinding head 28. For enlarged abrading heads 28 having a maximum diameter between about 1.75mm and about 2.0mm, at least a portion of the tissue removal surface 37 is rotatable through a path having a diameter at least about 20% greater than the maximum nominal diameter of the eccentrically enlarged abrading head 28, preferably at least about 25% greater than the maximum nominal diameter of the eccentrically enlarged abrading head 28, and most preferably at least about 30% greater than the maximum nominal diameter of the eccentrically enlarged abrading head 28. For an enlarged grinding head 28 having a maximum diameter of about 2.0mm, at least a portion of the tissue removal surface 37 is rotatable through a path having a diameter at least about 30% greater than the maximum nominal diameter of the eccentrically enlarged grinding head 28, and preferably at least about 40% greater than the maximum nominal diameter of the eccentrically enlarged grinding head 28.

Preferably, the design parameters are selected such that the enlarged grinding head 28 is sufficiently eccentric such that when the grinding head is rotated on the stationary guide wire 15 at a rotational speed between about 20,000rpm and about 200,000rpm, at least a portion of the tissue removal surface 37 of the grinding head can rotate through a path (whether such a path is completely regular or circular) having a maximum diameter that is substantially greater than the maximum nominal diameter of the eccentric enlarged grinding head 28. In various embodiments, the present invention is capable of forming an orbital path having a maximum diameter that is incrementally greater by at least between about 50% and about 400% than the maximum nominal diameter of the eccentric enlarged grinding head 28. Such an orbital path preferably includes a maximum diameter that is between at least about 200% and about 400% greater than the maximum nominal diameter of the eccentric enlarged grinding head 28.

The present invention should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the invention. Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the instant specification.

Claims (64)

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

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

a flexible elongate rotatable drive shaft advanceable over the guide wire, the drive shaft having an axis of rotation; and

at least one eccentric grinding head attached to said drive shaft, said grinding head comprising a proximal portion, an intermediate portion and a distal portion, wherein said proximal portion comprises a proximal outer surface, said intermediate portion comprises an intermediate outer surface, and said distal portion comprises a distal outer surface, said proximal outer surface having a distally increasing diameter, said distal outer surface having a distally decreasing diameter, said intermediate outer surface being cylindrical, wherein at least said intermediate outer surface comprises a tissue-removing portion, and wherein said grinding head defines a drive shaft lumen therethrough at least partially through said drive shaft lumen and a hollow cavity.

2. The rotational atherectomy device of claim 1 wherein the at least one eccentric abrading head is at least partially flexible.

3. The rotational atherectomy device of claim 2, wherein the at least one eccentric abrading head comprises at least one flexible slot disposed on the proximal, intermediate, and/or distal portions, wherein the at least one flexible slot has a controllable width, depth, and cutting angle.

4. The rotational atherectomy device of claim 1 wherein the at least one eccentric abrading head is inflexible.

5. The rotational atherectomy device of claim 1 wherein the portion of the drive shaft passing through the drive shaft lumen and attached thereto comprises a single, unbroken drive shaft.

6. The rotational atherectomy device of claim 5 wherein the section of the drive shaft passing through and attached to the drive shaft lumen comprises at least two sections, each section being attached to the drive shaft lumen with a gap between the at least two drive shaft sections.

7. The rotational atherectomy device of claim 1 wherein the intermediate outer surface of the at least one eccentric abrading head comprises a distally increasing diameter.

8. The rotational atherectomy device of claim 1 wherein the intermediate outer surface of the at least one eccentric abrading head comprises a distally decreasing diameter.

9. The rotational atherectomy device of claim 1 wherein the intermediate outer surface of the at least one eccentric abrading head comprises a convex surface shaped to form a smooth transition between the proximal and distal outer surfaces.

10. The rotational atherectomy device of claim 1 wherein the proximal outer surface of the at least one eccentric abrading head is substantially defined by a lateral surface of a cone, the axis of the cone intersecting the rotational axis of the drive shaft.

11. The rotational atherectomy device of claim 1 wherein the distal outer surface of the at least one eccentric abrading head is substantially defined by a lateral surface of a cone, the axis of the cone intersecting the rotational axis of the drive shaft.

12. The rotational atherectomy device of claim 1 wherein the proximal, distal and intermediate outer surfaces comprise tissue removal sections.

13. The rotational atherectomy device of claim 1 wherein only the intermediate outer surface comprises a tissue removal section.

14. The rotational atherectomy device of claim 1, further comprising at least one wall separating the proximal, distal and intermediate outer surfaces from the hollow cavity, wherein the at least one wall has a minimum thickness of 0.008 inches.

15. The rotational atherectomy device of claim 11 wherein the cone axis of the proximal outer surface and the cone axis of the distal outer surface intersect each other and are coplanar with the rotational axis of the drive shaft.

16. The rotational atherectomy device of claim 1 wherein the distal outer surface has a diameter that increases distally at a substantially constant rate, thereby forming a substantially conical shape.

17. The rotational atherectomy device of claim 16 wherein the proximal outer surface has a diameter that decreases distally at a substantially constant rate, thereby forming a substantially conical shape.

18. The rotational atherectomy device of claim 17 wherein opposite sides of each cone are at an angle α of between about 10 ° and 30 ° relative to each other.

19. The rotational atherectomy device of claim 17 wherein opposite sides of each cone are at an angle α of between about 20 ° and 24 ° relative to each other.

20. The rotational atherectomy device of claim 17 wherein each cone of the at least one eccentric abrading head has an axis which is not parallel to the rotational axis of the drive shaft.

21. The rotational atherectomy device of claim 17 wherein the axes of the cones of the at least one eccentric abrading head are coplanar and intersect the rotational axis of the drive shaft at an angle β between about 2 ° and 8 °.

22. The rotational atherectomy device of claim 17 wherein the axes of the cones of the at least one eccentric abrading head are coplanar and intersect the rotational axis of the drive shaft at an angle β between about 3 ° and 6 °.

23. The rotational atherectomy device of claim 1 wherein the proximal outer surface comprises at least two areas, a first of the two areas being substantially defined by a lateral surface of a frustum of a first cone and a second of the two areas being substantially defined by a lateral surface of a frustum of a second cone, the first cone having an axis which coincides with the rotational axis of the drive shaft and the second cone having an axis which is parallel to and spaced away from the axis of the first cone.

24. The rotational atherectomy device of claim 1 wherein the distal outer surface comprises at least two areas, a first of the two areas being substantially defined by a lateral surface of a frustum of a first cone and a second of the two areas being substantially defined by a lateral surface of a frustum of a second cone, the first cone having an axis coincident with the rotational axis of the drive shaft and the second cone having an axis parallel to and spaced away from the axis of the first cone.

25. The rotational atherectomy device of claim 23 wherein an angle formed between the lateral surface of the first cone and the axis of the first cone is greater than an angle formed between the lateral surface of the second cone and the axis of the second cone.

26. The rotational atherectomy device of claim 24 wherein an angle formed between the lateral surface of the first cone and the axis of the first cone is greater than an angle formed between the lateral surface of the second cone and the axis of the second cone.

27. The rotational atherectomy device of claim 1 wherein the distal outer surface and the proximal outer surface each comprise at least two areas, a first of the two areas being substantially defined by a lateral surface of a frustum of a first cone and a second of the two areas being substantially defined by a lateral surface of a frustum of a second cone, the first cone having an axis which coincides with the rotational axis of the drive shaft and the second cone having an axis which is parallel to and spaced away from the axis of the first cone.

28. The rotational atherectomy device of claim 27 wherein the second cones of the proximal and distal outer surfaces have a common axis that is parallel to and spaced away from the rotational axis of the drive shaft.

29. The rotational atherectomy device of claim 27 wherein the intermediate outer surface is substantially defined by a lateral surface of a cylinder.

30. The rotational atherectomy device of claim 29 wherein the two second cones of the proximal and distal outer surfaces each have a base having a diameter equal to the diameter of the cylinder forming the intermediate outer surface.

31. The rotational atherectomy device of claim 27 wherein the intermediate outer surface is substantially defined by a lateral surface of a cylinder having an axis that is common with the axis of the second cones of the proximal and distal outer surfaces.

32. The rotational atherectomy device of claim 27 wherein the intermediate outer surface is shaped to provide a smooth transition between the proximal and distal outer surfaces of the eccentric abrading head.

33. The rotational atherectomy device of claim 27 wherein the proximal and distal outer surfaces of the at least one eccentric abrading head are substantially symmetrical with respect to each other.

34. The rotational atherectomy device of claim 27 wherein the proximal and distal outer surfaces of the at least one eccentric abrading head are asymmetrical with respect to each other.

35. The rotational atherectomy device of claim 1 wherein the proximal outer surface comprises at least two areas, a first of the two areas being substantially defined by a lateral surface of a proximal cone and a second of the two areas being substantially defined by a lateral surface of a cylinder, the proximal cone having an axis coincident with the rotational axis of the drive shaft and the cylinder having an axis parallel to and spaced away from the rotational axis of the drive shaft.

36. The rotational atherectomy device of claim 35 further comprising the distal outer surface comprising at least two areas, a first of the two areas being substantially defined by a lateral surface of a distal cone and a second of the two areas being substantially defined by a lateral surface of a cylinder, the distal cone having an axis coincident with the rotational axis of the drive shaft and the cylinder having an axis parallel to and spaced away from the rotational axis of the drive shaft.

37. The rotational atherectomy device of claim 36 wherein the intermediate outer surface is substantially defined by a lateral surface of the cylinder defining the second areas of the proximal and distal outer surfaces of the at least one eccentric abrading head.

38. The rotational atherectomy device of claim 1 wherein the at least one eccentric abrading head has a center of mass that is radially spaced from the rotational axis of the drive shaft.

39. The rotational atherectomy device of claim 38 wherein the eccentric enlarged diameter section has a maximum diameter between about 1.0mm and about 1.5mm, and the center of mass is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.013 mm.

40. The rotational atherectomy device of claim 38 wherein the eccentric enlarged diameter section has a maximum diameter between about 1.5mm and about 1.75mm, and the center of mass is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.03 mm.

41. The rotational atherectomy device of claim 38 wherein the eccentric enlarged diameter section has a maximum diameter between about 1.75mm and about 2.0mm, and the center of mass is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.06 mm.

42. The rotational atherectomy device of claim 38 wherein the eccentric enlarged diameter section has a maximum diameter of at least about 2.0mm and the center of mass is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.1 mm.

43. The rotational atherectomy device of claim 38 wherein the eccentric enlarged diameter section has a maximum diameter between about 1.0mm and about 1.5mm, and the center of mass is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.02 mm.

44. The rotational atherectomy device of claim 38 wherein the eccentric enlarged diameter section has a maximum diameter between about 1.5mm and about 1.75mm, and the center of mass is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.05 mm.

45. The rotational atherectomy device of claim 38 wherein the eccentric enlarged diameter section has a maximum diameter between about 1.75mm and about 2.0mm, and the center of mass is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.1 mm.

46. The rotational atherectomy device of claim 38 wherein the eccentric enlarged diameter section has a maximum diameter of at least about 2.0mm and the center of mass is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.16 mm.

47. The rotational atherectomy device of claim 1 wherein a face of the cross-section of the eccentric enlarged diameter section is taken at a location of greatest cross-sectional diameter of the eccentric enlarged diameter section, the face having a geometric center spaced away from the rotational axis of the drive shaft.

48. The rotational atherectomy device of claim 47 wherein the eccentric enlarged diameter section has a maximum cross-sectional diameter between about 1.0mm and about 1.5mm, and the geometric center is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.02 mm.

49. The rotational atherectomy device of claim 47 wherein the eccentric enlarged diameter section has a maximum cross-sectional diameter between about 1.5mm and about 1.75mm, and the geometric center is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.05 mm.

50. The rotational atherectomy device of claim 47 wherein the eccentric enlarged diameter section has a maximum cross-sectional diameter between about 1.75mm and about 2.0mm, and the geometric center is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.1 mm.

51. The rotational atherectomy device of claim 47 wherein the eccentric enlarged diameter section has a maximum cross-sectional diameter of at least about 2.0mm, and the geometric center is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.15 mm.

52. The rotational atherectomy device of claim 47 wherein the eccentric enlarged diameter section has a maximum cross-sectional diameter between about 1.0mm and about 1.5mm, and the geometric center is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.035 mm.

53. The rotational atherectomy device of claim 47 wherein the eccentric enlarged diameter section has a maximum cross-sectional diameter between about 1.5mm and about 1.75mm, and the geometric center is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.07 mm.

54. The rotational atherectomy device of claim 47 wherein the eccentric enlarged diameter section has a maximum cross-sectional diameter between about 1.75mm and about 2.mm, and the geometric center is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.15 mm.

55. The rotational atherectomy device of claim 47 wherein the eccentric enlarged diameter section has a maximum cross-sectional diameter of at least about 2.0mm, and the geometric center is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.25 mm.

56. The rotational atherectomy device of claim 47 wherein the eccentric enlarged diameter section has a maximum cross-sectional diameter between about 1.5mm and about 1.75mm, and the geometric center is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.09 mm.

57. The rotational atherectomy device of claim 47 wherein the eccentric enlarged diameter section has a maximum cross-sectional diameter between about 1.75mm and about 2.0mm, and the geometric center is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.20 mm.

58. The rotational atherectomy device of claim 47 wherein the eccentric enlarged diameter section has a maximum cross-sectional diameter of at least about 2.0mm, and the geometric center is spaced away from the rotational axis of the drive shaft by a distance of at least about 0.30 mm.

59. The rotational atherectomy device of claim 1 wherein the tissue removal surface is an abrasive surface.

60. A high-speed rotational atherectomy device for opening a stenosis in an artery having a given diameter, the device comprising:

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

a flexible elongate rotatable drive shaft advanceable over the guide wire, the drive shaft having an axis of rotation; and

at least one semi-coronal eccentric grinding head attached to said drive shaft, said grinding head comprising a proximal portion and an intermediate portion, wherein said proximal portion comprises a proximal outer surface, said intermediate portion comprises an intermediate outer surface, said proximal outer surface having a distally increasing diameter, said distal outer surface having a distally decreasing diameter, said intermediate outer surface being cylindrical, wherein at least the intermediate outer surface comprises a tissue removal portion, and wherein said grinding head defines a drive shaft lumen therethrough at least partially therethrough through which said drive shaft passes and a hollow cavity.

61. The rotational atherectomy device of claim 60 wherein the proximal outer surface comprises at least two areas, a first of the two areas being substantially defined by a lateral surface of a proximal cone and a second of the two areas being substantially defined by a lateral surface of a cylinder, the proximal cone having an axis coincident with the rotational axis of the drive shaft and the cylinder having an axis parallel to and spaced away from the rotational axis of the drive shaft; and wherein said intermediate outer surface is substantially formed by side surfaces of said cylinder forming said second regions of said proximal and distal outer surfaces of said at least one eccentric grinding head.

62. The rotational atherectomy device of claim 60 wherein the at least one half-coronary eccentric abrading head is at least partially flexible.

63. The rotational atherectomy device of claim 61, wherein the at least one semi-coronary eccentric abrading head comprises at least one flexible slot disposed on the proximal, intermediate and/or distal portions, wherein the at least one flexible slot has a controllable width, depth and cutting angle.

64. A method for opening a stenosis in an artery having a given diameter, the method comprising:

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

advancing the guidewire into the artery to a location proximal to the stenosis;

providing a flexible, elongate, rotatable drive shaft advanceable over the guide wire, the drive shaft having an axis of rotation;

providing at least one eccentric grinding head attached to the drive shaft, the grinding head comprising at least a proximal portion and an intermediate portion, wherein the proximal portion comprises a proximal outer surface, the intermediate portion comprises an intermediate outer surface, the proximal outer surface having a distally increasing diameter, the distal outer surface having a distally decreasing diameter, the intermediate outer surface being cylindrical, wherein at least the intermediate outer surface comprises a tissue-removing portion, and wherein the grinding head defines a drive shaft lumen therethrough through which the drive shaft passes at least partially and a hollow cavity;

advancing the drive shaft over the guide wire, wherein the at least one eccentric abrading head is adjacent the stenosis;

rotating the drive shaft and attached at least one eccentric grinding head at a speed between 20,000 and 200,000 rpm;

forming an orbital path through which the at least one eccentric grinding head passes; and

the stenosis is ground with at least one eccentric grinding head.