HK1144661A - Cleaning apparatus and method for high-speed rotational atherectomy devices - Google Patents

Description

Cleaning device and method for high speed rotational atherectomy device

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 generally to devices and methods for maximizing the efficiency with which tissue is removed from a body passageway, such as atherosclerotic plaque from an artery, using a high speed rotational atherectomy device.

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 within a patient's artery. Atherosclerosis is characterized by the formation of fatty deposits (atheroma) in the inner layers (under the endothelium) of a patient's blood vessels. It is often the case that over time, the initially precipitated relatively soft cholesterol-rich atheromatous material tends to harden into calcified atherosclerotic plaques. Thus, atheroma restricts blood flow and is therefore commonly referred to as a stenotic lesion or stenosis, and the obstruction is referred to as a stenosis. Such stenosis can lead to angina, hypertension, myocardial infarction, stroke, etc., if left untreated.

Rotational atherectomy has become a common technique for removing such stenoses. Such procedures are commonly used to initiate the opening of calcified lesions in the coronary arteries. Most often, such rotational atherectomy procedures are not used alone, but are followed by balloon angioplasty, which is often followed by placement of a stent to help maintain patency of the opened artery. For non-calcified lesions, balloon angioplasty alone is typically used to open the artery, and a stent is also typically placed to maintain patency of the opened artery. However, studies have shown that a considerable number of patients who have undergone balloon angioplasty and have placed a stent within an artery experience restenosis of the stent, i.e. after some 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 yet very effective within the stent), whereby patency of the artery can be restored.

To remove stenosis, 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), a grinding file containing an abrasive cutting material, such as diamond particles, is mounted on the distal end of a flexible drive shaft. The grinding file is rotated at high speed (typically, for example, in the range of about 150,000 and 190,000 rpm) while the grinding file is advanced across the stenosis. However, when the abrasive file removes stenotic tissue, it is also … ….

U.S. patent No.5,314,438(Shturman) discloses another atherectomy device having a drive shaft with a portion of the drive shaft having an enlarged diameter, at least a section of the enlarged cutting head being coated with abrasive material to form an abrasive section of the drive shaft. The abrasive segment is capable of removing stenotic tissue from the artery when it is rotated at high speed.

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 an 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 a diameter 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 which is not bonded together, the enlarged eccentric portion of the drive shaft can flex during placement in a stricture or during high speed operation.

These prior art devices each include some form of abrasive cutting surface in some embodiments. As the abrasive cutting surfaces cut through the lesion, each of the abrasive cutting surfaces may become clogged or filled with various types of non-abrasive substances. When this phenomenon occurs, the cutting efficiency of grinding the cut surface is reduced. Accordingly, it is highly desirable to remove from the abrasive cutting surface those materials that adhere or otherwise bond to the abrasive cutting surface.

Disclosure of Invention

The present invention provides devices and methods for maximizing the efficiency of tissue removal from a body passageway. A rotational atherectomy device comprises, inter alia, an elongated, flexible, rotatable drive shaft having an enlarged cutting surface disposed thereon, a guidewire, and a catheter. The distal end of the catheter may have a cutting surface cleaner attached to or integrally formed on the distal end of the catheter. The cleaner is deflectable radially outwardly and biased against the drive shaft. The cleaner may be opened to accommodate the enlarged cutting surface for cleaning particles residing in the cutting surface as the cleaner is advanced distally over the drive shaft and/or the drive shaft is retracted proximally toward the cleaner to accommodate the enlarged cutting portion diameter. The cleaner includes an inner surface having an abrasive surface for mechanically scraping and removing material residing within the enlarged cutting head tissue removal surface.

Advantageously, certain embodiments of the present invention provide an apparatus and method for removing material from the cutting surface of an atherectomy device.

It is another object of the present invention to provide a device and method that improves the efficiency of removing tissue from a body passageway (e.g., removing a stenosis from an artery).

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 prior art high-speed rotational atherectomy device;

FIG. 2 is a cut-away perspective view of a cutting head for a high-speed rotational atherectomy device of the prior art;

FIG. 3 is a longitudinal cross-sectional view of a section of an eccentric cutting head formed by a drive shaft for a high-speed rotational atherectomy device of the prior art;

FIG. 4 is a fragmentary longitudinal cross-sectional view of a solid eccentric abrasive grinding file attached to a drive shaft for a prior art low speed rotational atherectomy device;

FIG. 5 is a perspective view of one embodiment of the cleaning and cutting apparatus of the present invention;

FIG. 6 is a perspective view of one embodiment of the cleaning and cutting apparatus of the present invention;

fig. 7 is a perspective view of an embodiment of the cleaning and cutting apparatus of the present invention.

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 herein. 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 a typical and exemplary rotational atherectomy device in which the present invention may be utilized. Such devices are generally described in U.S. Pat. No.5,314,438(Shturman) and U.S. Pat. No.6,494,890(Shturman), the entire contents of each of which are incorporated herein by reference.

The exemplary rotational atherectomy device of FIG. 1 comprises a handle portion 10, an elongated flexible drive shaft 20, an enlarged cutting portion 28, and an elongated catheter 13 extending distally from the handle portion 10. For exemplary purposes, the enlarged cutting portion 28 is shown as a solid piece attached to the drive shaft 20. This form of cutting portion 28 and others will be discussed further below. The drive shaft 20 and enlarged cutting portion 28 are constructed from helically coiled wire. The catheter 13 has a distal end and a lumen in which the majority of the length of the drive shaft 20 is disposed, except for an enlarged cutting portion 28 of the drive shaft 20 and a short segment at the distal end of the enlarged cutting portion 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.

Handle portion 10 desirably includes a turbine (or similar rotational drive mechanism) for rotating 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. 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.

Fig. 2-4 show details of the enlarged cutting portion of the prior art of fig. 1. FIG. 2 thus provides an enlarged and substantially concentric cutting portion for use in high-speed rotational atherectomy procedures, which includes concentric enlarged diameter portion 28 of drive shaft 20. Enlarged diameter portion 28 includes a proximal portion 30, an intermediate portion 35, and a distal portion 40. The eccentric enlarged diameter portion 28 also includes an outer surface that is capable of removing tissue. A tissue-removing surface 37 comprising a coating of abrasive material 24 forms a tissue-removing segment of the drive shaft 20, the tissue-removing surface 37 being shown attached directly to the turns of the drive shaft 20 with a suitable adhesive 26. The drive shaft 20 is comprised of one or more helically wound wires 18 that form a guide wire lumen 19 and a hollow cavity 25 within an enlarged cutting head 28. An enlarged cutting portion of this form, effected by the concentric enlarged diameter portion 28 of the drive shaft, is generally disclosed in U.S. patent No.5,314,438 to Shturman.

Turning now to FIG. 3, a cut-away, cross-sectional view of an enlarged cutting portion of another prior art form of a method for high-speed rotational atherectomy procedures is provided. Here, as described above, the eccentric enlarged diameter portion 28A of the drive shaft 20 rotating over the guide wire 15 includes the proximal end portion 30A, the intermediate portion 35A, and the distal end portion 40A. The eccentric enlarged diameter portion 28A also includes an abrasive outer surface that is capable of removing tissue. A tissue-removing surface 37 comprising a coating of abrasive material 24A forms a tissue-removing segment of the drive shaft 20. the tissue-removing surface 37 is shown attached directly to the turns of the drive shaft 20A with a suitable adhesive 26A. The turns 31 of the proximal portion 30A of the eccentric enlarged diameter portion 28A preferably gradually increase in diameter distally at a substantially constant rate, thereby forming a generally conical shape, and thus, a proximal conical portion and a distal conical portion. The turns 41 of the distal portion 40A preferably gradually decrease in diameter distally at a substantially constant rate, thereby forming a generally conical shape. The profile of the intermediate section 35 includes varying diameters of the assembly to provide a generally convex outer surface shaped to provide a smooth transition between the proximal and distal conical portions of the eccentric enlarged diameter portion 28A of the drive shaft 20. Thus, the prior art enlarged cutting portion exhibits an eccentric profile. Such an eccentric enlarged cutting portion 28A is generally disclosed in U.S. patent No.6,494,890 to Shturman.

Turning now to fig. 4, another prior art method for enlarging a cutting portion is provided. This solution uses a solid asymmetric grinding file 28B attached to a flexible drive shaft 20B that rotates at a low speed over the guide wire 15, as provided in U.S. patent No.5,681,336 to Clement, the entire contents of which are incorporated herein by reference. The eccentric tissue removal grinding file 28B has a coating of abrasive particles 24B secured to a portion of its outer surface with a suitable bonding material 26B.

Turning now to FIG. 1, and in conjunction with FIG. 5, the catheter 13 has a lumen in which a substantial length of the drive shaft 20 can be disposed, except for an enlarged cutting portion 28 of the drive shaft 20 and a short segment at the distal end of the enlarged cutting portion 28. The drive shaft 20 also contains a lumen 19 that allows the drive shaft 20 to advance and rotate over the guidewire 15.

As shown in FIG. 5, the distal end of catheter 13 may have a distal cutting surface cleaner 100 attached to or integrally formed within the distal end of catheter 13. Cleaner 100 may flex radially outward and be biased against drive shaft 20. When cleaner 100 is advanced distally on drive shaft 20 or drive shaft 20 is retracted proximally toward cleaner 100, cleaner 100 can be opened sufficiently to accommodate the enlarged diameter of cutting portion 28. Cleaner 100 includes an inner surface that also includes an abrasive surface 102 thereon that cleans and removes material that resides in tissue removal surface 37 of the enlarged cutting head. Thus, cleaner 100 can remove particles that reside within tissue removal surface 37 simply by passing tissue removal surface 37 longitudinally through cleaner 100 and causing abrasive surface 102 of the cleaner to scrape off the material.

Alternatively, tissue removal surface 37 can be moved into cleaner 100, and then drive shaft 20 rotated to provide additional force to dislodge particles residing within tissue removal surface 37.

The embodiment of cleaner 100 of FIG. 5 includes two openable sections 106, with a biasing force generally keeping the two openable sections 106 pressed against each other. The openable section 106 may be comprised of a rigid material or a semi-flexible material. Mechanisms for providing a radially inward biasing force to the openable section 106 of the present invention are well known to those skilled in the art. When the enlarged diameter portion 28A is pressed against the openable portions 106, the radially flexible openable portions 106 are forced to receive the enlarged diameter portion 28A and engage the tissue removal surface 37 with the abrasive surface 102 of the cleanser disposed on the inner surface 104 of each openable portion 106. The openable section 106 is shown in dashed lines in fig. 5 in the open position. Those skilled in the art will recognize that other equivalent embodiments of cleaner 100 are possible, particularly including more than two (upper and lower) openable sections 106. For example, two or more openable portions 106 may be employed, i.e., three or four or more openable portions 106. The radially inward biasing force of the openable section 106 of cleaner 100, in combination with the longitudinal movement of tissue removal surface 37 relative to cleaner abrasive surface 104 and/or the rotational movement of drive shaft 20, can provide sufficient force to scrape and dislodge particles residing within tissue removal surface 37.

The drawings show an enlarged eccentric diameter portion 28A of the drive shaft 20 with a tissue removal surface 37 disposed thereon, however, the invention is of course not limited to this illustrated embodiment of an enlarged cutting surface or enlarged cutting head. Those skilled in the art will recognize that alternative cutting surfaces or heads for high-speed rotational atherectomy may be cleaned in accordance with the present invention. Furthermore, those skilled in the art will recognize that low speed rotating cutting surfaces or heads may be cleaned in accordance with the present invention. Furthermore, the enlarged cutting surfaces may be eccentric or concentric. The enlarged cutting surface may be formed by the turns of the drive shaft or may be a grinding file mounted thereon. Each such enlarged cutting surface and/or cutting head is within the scope of the present invention.

Accordingly, the cutting surfaces defined herein include high or low speed rotational atherectomy cutting heads having abrasive surfaces. The cutting surface is further defined to include an enlarged diameter portion formed by the wire turns of the rotating atherectomy drive shaft, wherein the enlarged diameter portion may be eccentric or concentric, such as the embodiments of the invention shown herein. The cutting surface is further defined as comprising a solid, semi-solid or hollow cutting head and/or abrasive file having an abrasive surface, which are attached or mounted on a drive shaft of a rotational atherectomy procedure.

When the cutting surface 28A is located within the openable section 106, the cutting surface 28A may be rinsed with a saline solution introduced into the conduit 13 and thus into the cleaner 100 through the fluid supply line 17 shown in fig. 1. The cutting surface 28A may be rinsed with saline at any time after the cutting surface 28A has been pushed or urged open by the openable portion 106 and before, during, and/or after the cutting method described herein is performed. In this way, the abrasive cutting surface 28A can be cleaned during treatment. Therefore, it is not necessary to remove the abrasive cutting surface 28A from the patient to clean it.

Turning now to FIG. 6, another alternative embodiment of cleaner 100 is provided. In this embodiment, a plurality of openable sections 106 are provided, each openable section 106 being separated from the next adjacent openable section 106 by a gap 110. This configuration provides the openable section 106 with increased flexibility. Those skilled in the art will recognize that the gap 110 between adjacent openable sections 106 may be smaller than shown or may not be required. In other words, an alternative embodiment may include adjacent openable sections 106 configured with little or no gap 110 therebetween.

The cleaner of fig. 6 operates as described above in connection with fig. 5, except that there are more openable sections 106 with gaps 110 therebetween. Thus, when the enlarged diameter portion 28A is pressed against the cleaner, the openable portion 106 widens and opens to accommodate the enlarged diameter portion. As described in connection with fig. 5, the abrasive surface 102 on the interior of each openable section 106 can remove material residing on the abraded tissue removing surface 37 of the enlarged diameter portion 28A. This removal can be accomplished by proximal and/or distal longitudinal movement of tissue removal surface 37 relative to cleaner 100. Alternatively, rotation of drive shaft 20 and, therefore, tissue removal surface 37 within cleaner 100 may be used alone or in combination with longitudinal movement of tissue removal surface 37 relative to cleaner 100.

The openable section of fig. 5 and 6 shows such an openable section 106 having a diameter substantially the same as the diameter of the conduit 13 before introducing the enlarged cutting head 28A. Fig. 7 shows a slightly different embodiment in which the openable section 106 is formed with a diameter greater than the diameter of the conduit 13. This may provide additional biasing force on the tissue removal surface 37 by the openable section 106 as the surface 37 scrapes against the grinding surface on the interior of the openable section.

Methods of maximizing the efficiency of tissue removal from a body passageway according to the present invention may comprise: providing a cutting surface on an elongated flexible drive shaft; disposing a cleaner on a distal end of the elongated catheter; positioning an elongate catheter and an elongate flexible drive shaft within a lumen of the elongate catheter in a body passageway adjacent to a stenosis; rotating an elongated flexible drive shaft within a body passageway to abrade a stricture with a cutting surface; retracting the elongate flexible drive shaft proximally away from the stricture and toward the catheter's cleaner; opening the cleaner and inserting the cutting surface; curvilinearly mating the cutting surface with the abrasive surface of the cleaner to remove any material residing in the cutting surface; and continuing the grinding of the stenosis portion.

Additional method steps may include: rotating the drive shaft to enhance the scraping cleaning process, and/or longitudinally moving the catheter and/or drive shaft to cause the cleaner to longitudinally scrape the cutting surface, and/or rinsing the cutting surface with saline.

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 (20)

1. A high-speed rotational atherectomy device for abrading a stenosis in a body passageway, comprising:

a guide wire;

an elongated flexible catheter comprising a lumen, a distal end, and a distal cutting surface cleaner disposed on the distal end; and

an elongated flexible drive shaft comprising an enlarged cutting surface and a lumen, said drive shaft capable of advancing, retracting and rotating over said guidewire and at least a portion of said drive shaft capable of advancing, retracting and rotating within said lumen of said catheter.

2. The rotational atherectomy device of claim 1, wherein the distal cutting surface cleaner is attached to the distal end of the catheter.

3. The rotational atherectomy device of claim 1, wherein the distal cutting surface cleaner is integrally formed on the distal end of the catheter.

4. The rotational atherectomy device of claim 1, wherein the distal cutting surface cleaner further comprises at least two openable sections, the at least two openable sections being radially outwardly deflectable and radially inwardly biased.

5. The rotational atherectomy device of claim 1, wherein the distal cutting surface cleaner further comprises a plurality of openable sections, the plurality of openable sections being radially outwardly deflectable and radially inwardly biased.

6. The rotational atherectomy device of claim 4, wherein the at least two openable sections further comprise an inner surface, the inner surface comprising an abrasive material.

7. The rotational atherectomy device of claim 4 wherein the distal cutting surface cleaner is capable of at least partially receiving the enlarged cutting surface therein and curvilinearly engaging the cutting surface with the abrasive material of the inner surface.

8. The rotational atherectomy device of claim 1 wherein the enlarged cutting surfaces are concentric.

9. The rotational atherectomy device of claim 1 wherein the enlarged cutting surface is eccentric.

10. The rotational atherectomy device of claim 1 wherein the drive shaft comprises helically wound wire turns, wherein the enlarged cutting surface is formed by the wire turns.

11. The rotational atherectomy device of claim 1 wherein the enlarged cutting surface is mounted to the drive shaft.

12. The rotational atherectomy device of claim 4, wherein the at least two openable sections are disposed adjacent to each other with no gap therebetween.

13. The rotational atherectomy device of claim 4, wherein the at least two openable sections are disposed adjacent to each other with a gap therebetween.

14. A rotational atherectomy device for abrading a stenosis in a body passageway, comprising:

a guide wire;

an elongated flexible catheter comprising a lumen, a distal end, and a distal cutting surface cleaner disposed on the distal end, the distal cutting surface cleaner comprising at least two openable portions that are flexible radially outward and biased radially inward, the at least two openable portions comprising an inner surface comprising an abrasive material thereon;

an elongated flexible drive shaft including an enlarged cutting surface and a lumen disposed thereon, said drive shaft being capable of advancing, retracting and rotating over said guidewire and within said lumen of said catheter, wherein said distal cutting surface cleaner is capable of at least partially receiving said enlarged cutting surface therein and curvilinearly engaging said cutting surface with abrasive material on an inner surface of said at least two openable portions of said cutting surface cleaner.

15. A method for abrading a stricture site within a body passageway, the method comprising:

providing a cutting surface on an elongated flexible and rotatable drive shaft;

disposing a cleaner on a distal end of the elongated catheter;

positioning the elongate catheter and the elongate flexible drive shaft within the lumen of the elongate catheter within a body passageway adjacent to a stricture site within the body passageway;

rotating the elongated flexible drive shaft within the body passageway to abrade the stenosis with the cutting surface;

retracting the elongated flexible drive shaft proximally away from the stricture and toward the catheter cleaner;

urging the cleaner into an open position and sliding the cutting surface into the open cleaner;

curvilinearly mating the cutting surface with the cleaner's grinding surface to remove any material residing within the cutting surface; and

continuing the grinding of the stenosis.

16. The method of claim 15 further comprising rotating the drive shaft to enhance cleaning of the cutting surface with the abrasive surface of the cleaner.

17. The method of claim 16, further comprising moving the conduit and/or drive shaft longitudinally to cause the abrasive surface of the cleaner to scrape the cutting surface longitudinally.

18. The method of claim 15 further comprising flushing the cutting surface with saline while scrapingly engaging the cutting surface with the cleaner's grinding surface to remove any material resident in the cutting surface.

19. The method of claim 18, further comprising flushing the cutting surface with saline after curettably mating the cutting surface with the cleaner's grinding surface to remove any material residing within the cutting surface.

20. The method of claim 19, further comprising performing the cleaning operation within the body passageway without removing the drive shaft or catheter from the body passageway.