Tissue-removing catheter with rotatable cutter

A tissue-removing catheter includes a cutting element. A radially innermost portion of the leading radial wall of a raised element of the cutting element may be spaced a radial distance from the longitudinal axis that is less than 66% of the radius of the annular cutting edge. The cutting element may be extendable through the window during operation such that as the cutting element is being rotated about its longitudinal axis, less than an entire radial portion of the leading radial wall passes through the window. A plurality of abrading members may be formed on at least the central portion of the inner surface of the cutting element to abrade hardened tissue as the cutting element is rotating about its longitudinal axis. A radially outermost portion of the leading radial edge of the raised element may be spaced apart radially from an inner surface of the cutting element.

FIELD OF THE DISCLOSURE

The present invention generally relates to tissue-removing catheter with a rotatable cutter.

BACKGROUND

Catheters are used to remove unwanted tissue from the body. As an example, atherectomy catheters are used to remove material from a blood vessel to open the blood vessel and improve blood flow through the vessel.

SUMMARY

In one aspect, a tissue-removing catheter generally comprises an elongate catheter body having opposite distal and proximal portions and being sized and shaped for introduction into a body lumen of a subject. A drive shaft extends longitudinally within the catheter body. The drive shaft is rotatable relative to the catheter body about a longitudinal axis of the drive shaft. A cutting element at the distal portion of the elongate catheter body has opposite proximal and distal ends and a longitudinal axis extending therebetween. The cutting element is operatively connected to the drive shaft for rotation about a longitudinal axis of the cutting element. The cutting element includes an annular cutting edge at the distal end of the cutting element surrounding the longitudinal axis of the cutting element. The annular cutting edge has a radius as taken from the longitudinal axis of the cutting element. An inner surface of the cutting element extends proximally from the cutting edge and defines an internal cavity. At least one raised element in the internal cavity of the cutting element extends generally longitudinally outward from the inner surface. The at least one raised element includes a leading radial wall extending generally radially inward toward the longitudinal axis of the cutting element. The leading radial wall has a radially outermost portion relative to the longitudinal axis of the cutting element, a radially innermost portion relative to the longitudinal axis of the cutting element, and a radial length extending between the radially outermost and innermost portions. The radially innermost portion of the leading radial wall is spaced a radial distance from the longitudinal axis that is less than 66% of the radius of the annular cutting edge.

In another aspect, a tissue-removing catheter generally comprises an elongate catheter body having opposite distal and proximal portions and being sized and shaped for introduction into a body lumen of a subject. The catheter body has a window at the distal portion thereof. A drive shaft extends longitudinally within the catheter body. The drive shaft is rotatable relative to the catheter body about a longitudinal axis of the drive shaft. A cutting element at the distal portion of the elongate catheter body is adjacent the window. The cutting element has opposite proximal and distal ends and a longitudinal axis extending therebetween, the cutting element being operatively connected to the drive shaft for rotation about the longitudinal axis of the cutting element. The cutting element includes an annular cutting edge at the distal end of the cutting element surrounding the longitudinal axis of the cutting element, the annular cutting edge having a radius as taken from the longitudinal axis of the cutting element. An inner surface of the cutting element extends proximally from the cutting edge and defining an internal cavity. At least one raised element in the internal cavity has leading radial wall extending generally radially inward toward the longitudinal axis of the cutting element. The cutting element is extendable through the window during operation such that as the cutting element is being rotated about its longitudinal axis, less than an entire radial portion of the leading radial wall passes through the window.

In another aspect, a tissue-removing catheter generally comprises an elongate catheter body having opposite distal and proximal portions and being sized and shaped for introduction into a body lumen of a subject. A drive shaft extends longitudinally within the catheter body, wherein the drive shaft is rotatable relative to the catheter body about a longitudinal axis of the drive shaft. A cutting element at the distal portion of the elongate catheter body has opposite proximal and distal ends and a longitudinal axis extending therebetween. The cutting element is operatively connected to the drive shaft for rotation about a longitudinal axis of the cutting element. The cutting element includes an annular cutting edge at the distal end of the cutting element surrounding the longitudinal axis of the cutting element. The annular cutting edge has a radius as taken from the longitudinal axis of the cutting element. An inner surface extends proximally from the cutting edge and defining an internal cavity. At least one raised element in the internal cavity extends generally longitudinally outward from the inner surface. The at least one raised element includes a leading radial wall extending generally radially inward toward the longitudinal axis of the cutting element. The leading radial wall has a radially outermost portion relative to the longitudinal axis of the cutting element, a radially innermost portion relative to the longitudinal axis of the cutting element, and a radial length extending between the radially outermost and innermost portions. The radially outermost portion is spaced apart radially from the inner surface of the cutting element.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, several embodiments of a tissue-removing catheter for removing tissue from a body lumen are disclosed. In particular, the illustrated catheter embodiments are suitable for removing tissue from a body lumen wall, and are particularly suitable for removing (i.e., excising) plaque tissue from a vessel wall (e.g., peripheral arterial or peripheral venous wall). Features of the disclosed embodiments, however, may also be suitable for treating chronic total occlusion (CTO) of blood vessels, particularly peripheral arteries, and stenoses of other body lumens and other hyperplastic and neoplastic conditions in other body lumens, such as the ureter, the biliary duct, respiratory passages, the pancreatic duct, the lymphatic duct, and the like. Neoplastic cell growth will often occur as a result of a tumor surrounding and intruding into a body lumen. Removal of such material can thus be beneficial to maintain patency of the body lumen. While the remaining discussion is directed toward catheters for removing tissue from and penetrating occlusions in blood vessels (e.g., atheromatous or thrombotic occlusive material in an artery, or other occlusions in veins), it will be appreciated that the teachings of the present disclosure apply equally to other types of tissue-removing catheters, including, but not limited to, catheters for penetrating and/or removing tissue from a variety of occlusive, stenotic, or hyperplastic material in a variety of body lumens.

Referring toFIGS. 1 to 4, an atherectomy catheter2, which has a cutting element4, which is used to cut material from a blood flow lumen. The catheter has an elongate body8having distal and proximal portions and being sized and shaped for insertion into a body lumen of a subject. The cutting element4is movable between a stored position (FIG. 2) and a cutting position (FIG. 3) relative to a window or opening6in the catheter body8adjacent the distal portion. The cutting element8moves outwardly relative to the opening6so that an exposed portion of the element4extends outside the body8through the opening6. The cutting element4may be positioned relative to the body8and opening6so that less than 90 degrees of the cutting element4is exposed to cut tissue. Of course, more of the cutting element4may be exposed without departing from numerous aspects of the invention.

Catheter2may have a maximum size of 3, 4, 5, 6, 7, 8, 9, 10, or 12 French (1, 1.3, 1.7, 2, 2.3, 2.7, 3, 3.3, or 4 mm) and may have a working length ranging of 20, 30, 40, 60, 80, 100, 120, 150, 180 or 210 cm depending on the requirements of the anatomical location in which use of the catheter is contemplated. Cutter4preferably has a diameter slightly less than that of the maximum size of catheter2, typically 0.010″ (0.025 cm), 0.015″ (0.038 cm), 0.020″ (0.051 cm), 0.025″ (0.064 cm) or 0.030″ (0.076 cm) less. However these relative dimensions are not meant to be limiting.

The catheter2is moved distally through a vessel with the cutting element4in the working or cutting position as described in further detail below. As the catheter2moves through the blood vessel, the tissue is cut by the cutting element4and is directed into a tissue chamber12positioned distal to the cutting element4. The tissue chamber12may be somewhat elongate to accommodate the tissue that has been cut.

The cutting element4is moved proximally from the stored position so that a cam surface14on the cutting element4engages a ramp16on the body8of the catheter2. The interaction between the cam surface14and the ramp16causes the cutting element4to move to the cutting position and also causes a tip18to deflect which tends to move the cutting element4toward the tissue to be cut.

The cutting element4is coupled to a drive shaft20that extends through a lumen21in the catheter2. The cutting element4is rotated about a longitudinal axis LA when the drive shaft rotates about its longitudinal axis. The cutting element4is rotated at about 1 to 160,000 rpm but may be rotated at any other suitable speed depending upon the particular application.

Referring toFIGS. 2, 4 and 5, the cutting element4is shown. The term “along the longitudinal axis” as used herein shall mean the view ofFIG. 5that shows the distal end of the cutting element4when viewed in the direction of the longitudinal axis and/or the axis of rotation. The cutting element4has an annular cutting edge22that may be a continuous, uninterrupted, circular-shaped edge although it may also include ridges, teeth, serrations or other features without departing from the scope of the invention. The cutting edge22may be at a radially outer edge23of the cutting element4when the cutting element4is in the cutting position. A circumferential inner surface25of the cutting element4extends from the cutting edge22and is chamfered or beveled.

The cutting element4has an inner cup-shaped surface24, which directs the tissue cut by the cutting edge22into the tissue chamber12. In the illustrated embodiment, the circumferential inner surface25and the inner cup-shaped surface24define an internal cavity of the cutting element4. The cup-shaped surface24may be a smooth and continuous surface free of through-holes, teeth, fins or other features, which disrupt the smooth nature of the surface24for at least half the distance from the longitudinal axis LA to the outer radius at the cutting edge22. The cup-shaped surface24may also be free of any such features throughout an area of at least 300 degrees relative to the longitudinal axis LA.

Referring toFIGS. 4 to 6, one or more raised elements26extend outwardly from the cup-shaped surface24withFIG. 5showing two raised elements26. The raised element26is a small wedge of material that rises relatively abruptly from the cup-shaped surface24. The raised element26has a first wall30and a second wall32that both extend radially and form an angle of about 20 degrees therebetween so that the two raised elements26together occupy an area of about 40 degrees and altogether may be less than 60 degrees. A third wall34extends between the radially inner portion of the first and second walls30,32. The raised element26helps to break up hard tissue and plaque by applying a relatively blunt force to the hard tissue or plaque since cutting such tissue with the cutting edge22is often not effective.

The raised elements26altogether occupy a relatively small part of the cup-shaped surface24. The raised elements26together may occupy less than 5% of a surface area of the cutting element4. The term “surface area of the cutting element” as used herein shall mean the surface area which is radially inward from the outer or cutting edge22and is exposed when viewed along the longitudinal axis LA. Stated another way, at least 95% of the surface area of the cutting element is a smooth cup-shaped surface when viewed along the longitudinal axis. However, the raised element surface area may occupy more of the total surface area of the cup. By sizing and positioning the raised element26in this manner, the raised element26does not interfere with the ability of the cutting element4to cut and re-direct tissue into the tissue chamber while still providing the ability to break up hard tissue and plaque with the raised element26.

The raised element26may be recessed from the cutting edge22longitudinally and/or radially. The raised element26may be recessed longitudinally (along axis LA) from the cutting edge 0.0010 to 0.0020 inch (0.0025 to 0.0051 cm) and may be recessed about 0.0015 inch (0.0038 cm). The raised element26may be recessed radially from the cutting edge22by about the same amount. A distal wall38of the cutting element4forms a flat surface40, which is perpendicular to the longitudinal axis LA so that the entire surface is recessed the same distance from the cutting edge. The distal wall38may take any other shape, such as a curved shape, or may be tilted, inclined or beveled as now described. The raised element may have other shapes, sizes and locations within the scope of the present invention.

Referring toFIGS. 7, 8 and 8A, another cutting element4A is shown wherein the same or similar reference numbers refer to the same or similar structure and all discussion concerning the same or similar features of the cutting element4are equally applicable here unless noted otherwise. The cutting element4A has a cutting edge22A that may be a continuous, uninterrupted, circular-shaped edge although it may also include ridges, teeth, serrations or other features without departing from the scope of the invention. The cutting edge22A may be at a radially outer edge23A of the cutting element4A when the cutting element4A is in the cutting position. The cutting element4A has a cup-shaped surface24A that directs the tissue cut by the cutting edge22A into the tissue chamber12(seeFIG. 2). The cup-shaped surface24A may be a substantially smooth and continuous surface as described above in connection with the cutting element4.

One or more raised elements26A extend outwardly from the cup-shaped surface24A.FIG. 8shows four raised elements26A but may include any number such as 1, 2, 3, 4, 6 or 8 raised elements. The raised element26A is a small wedge of material that rises relatively abruptly from the cup-shaped surface24A. The raised element26A has a first wall30A and a second wall32A which, in one embodiment, both extend radially and form an angle of about 1 to 30 degrees therebetween so that the four raised elements26A together occupy an area of about 4 to 60 degrees and altogether may be less than 60 degrees. A third wall34A extends between the radially inner portion of the first and second walls30A,32A. In some embodiments the raised elements26A may occupy a relatively small part of the cup-shaped surface24A and may be recessed from the cutting edge22A in the manner described above in connection with the cutting element4. In other embodiments at least 60%, 70%, 80% or 90% of the surface area of the cutting element is a smooth cup-shaped surface.

A distal wall38A of the cutting element4A has a surface40A that forms an angle of about 30 to 90 degrees with respect to the longitudinal axis LA. The entire surface40A may still be somewhat close to but recessed from the cutting edge22A so that the entire surface40A is at least 0.0010, 0.0020, 0.0030, 0.0040 or 0.0050 inches (0.0025, 0.0051, 0.0076, 0.0101, or 0.0127 cm) from the cutting edge. A leading edge50formed at the intersection of wall30A and distal wall38A is closer to the cutting edge22A than an edge52formed at the intersection of wall32A and distal wall38A. The cutting element4A may be rotated in either direction so that the raised edge50may be the leading or trailing edge. In some embodiments the raised edge may be 0.0010 to 0.0020 inch (0.0025 to 0.0051 cm) from the cutting edge. The raised elements26A may all be formed in the same manner or may be different from one another. For example, some of the elements26A could be angled in different directions so that two of the elements have the raised edge50as the leading edge and two of the elements26A have the raised edge50as the trailing edge. The raised elements26A may also subtend different angles, be of different heights or may have different radial lengths without departing from various aspects of the present invention.

Referring toFIGS. 9, 10 and 10A, another cutting element4B is shown wherein the same or similar reference numbers refer to the same or similar structure and all discussion concerning the same or similar features of the cutting element4are equally applicable here unless noted otherwise. The cutting element4B has a cutting edge22B that may be a continuous, uninterrupted, circular-shaped edge although it may also include ridges, teeth, serrations or other features without departing from the scope of the invention. The cutting edge22B may be at a radially outer edge23B of the cutting element4B when the cutting element4B is in the cutting position. The cutting element4B has a cup-shaped surface24B that directs the tissue cut by the cutting edge22B into the tissue chamber12(seeFIG. 2). In one embodiment the cup-shaped surface24B may be a substantially smooth and continuous surface as described above in connection with the cutting element4.

One or more raised elements26B, extend outwardly from the cup-shaped surface24B.FIGS. 9 and 10show four raised elements26B but may include any number such as 1, 2, 3, 4, 6 or 8 raised elements. The raised element26B is a small wedge of material that rises relatively abruptly from the cup-shaped surface24B and which subtends an arc of about 1 to 30 degrees relative to axis LA, the four raised elements26B subtending an arc of about 4 to 60 degrees altogether. The raised element26B has a first wall30B that extends between a curved leading edge50B and cup-shaped surface24B and also has a second wall32B which extends radially relative to axis LA. A third wall34B extends between the radially inner portion of the first and second walls30B,32B. In some embodiments the raised elements26B may occupy a relative small part of the cup-shaped surface24B and may be recessed from the cutting edge22B in the manner described above in connection with the cutting element4. In other embodiments at least 60%, 70%, 80% or 90% of the surface area of the cutting element is a smooth cup-shaped surface.

A distal wall38B of the cutting element4B has a surface40B that forms an angle of less than 90 degrees with respect to the longitudinal axis LA. In some embodiments the surface40B is angled such that edge50B is more distal than edge52B. The entire surface40B may still be somewhat close to but recessed from the cutting edge22B so that the entire surface40B is from 0.0010 to 0.0050 inch (0.0025 to 0.0127 cm), including 0.0010, 0.0020, 0.0030, 0.0040 or 0.0050 inch (0.0025, 0.0051, 0.0076, 0.0101, or 0.0127 cm), from the cutting edge. An edge50B formed at the intersection of wall30B and distal wall38B is closer to the cutting edge22B than an edge52B formed at the intersection of wall32B and distal wall38B. The included angle between wall30B and surface40B, in the vicinity of edge50B, is greater than 90 degrees. The cutting element4B may be rotated in either direction so that the raised edge50B may be the leading or trailing edge. In one embodiment, the cutter4B is rotated in the direction of arrow R so that edge50B is the leading edge. Raised edges50B,52B may be 0.0010 to 0.0020 inch (0.0025 to 0.0051 cm) from the cutting edge. The raised elements26B may all be formed in the same manner or may be different from one another. For example, some of the elements26B could be angled in different directions so that two of the elements have the raised edge50B as the leading edge and two of the elements26A have the raised edge50B as the trailing edge. The raised elements26B may also subtend different angles, be of different heights or may have different radial lengths without departing from various aspects of the present invention.

In one embodiment cutter4B is rotated in the direction of arrow R and pushed distally to force cup-shaped surface24B and raised elements26B into contact with material such as atheroma or plaque. Raised elements26B will tend to concentrate cutting force along edge50B due to relief angle between cutter axis LA and surface40B. Cutter4B will tend to scrape away material such as atheroma or plaque rather than cut into this material due to the obtuse included angle between wall30B and surface40B, in the vicinity of edge50B. Material contacted by raised elements26B will tend to be directed toward axis LA by surface30B which curves from a relatively tangential angle near edge22B to a relatively radial angle near edge34B.

Referring toFIGS. 11 and 11A, another cutting element4C is shown. Cutting element4C is a modified version of cutting element4A. The modification consists of adding an undercut41C to the leading face of one or more raised element26A, resulting in modified raised element26C. When cutter4C is rotated in the direction of arrow T the undercut directs particles of material into the concave cavity defined by cup-shaped surface24A of the cutter, and towards axis LA of the cutter. Optionally an undercut can be applied to the leading face of one or more raised element26,26B of cutting elements4,4B respectively as well as to one or more raised elements26A of cutting element4A.

Undercut41C is defined by wall30C which is oriented at an acute angle to surface40A, which intersects cup-shaped surface24A, and which meets wall34A. The plane of wall30C also intersects axis LA at less than 5, 10, 15, or 20 degrees such that, when cutter4C is spinning in direction T, particles of material tend to travel along wall30C in directions away from cutting edge22A and toward axis LA. In some embodiments wall43C may be interspersed between the intersection of wall30C and wall40A. Wall43C may be oriented at any desired rake angle, such as for example a negative rake angle where the raised element will tend to not dig in to material being cut.

Referring toFIGS. 12-18, another embodiment of a cutting element is indicated generally at4D. The cutting element4D is similar to cutting element4B, except that, as explained below, radial lengths of the raised elements, generally indicated at26D, are greater than radial lengths of the raised elements26B of the cutting element4B. The cutting element4D has an annular cutting edge22D that may be a continuous, uninterrupted, arcuate-shaped edge although it may also include ridges, teeth, serrations or other features without departing from the scope of the invention. In the illustrated embodiment, an inner surface of the cutting element4D defines an internal cavity of the cutting element. The inner surface includes a circumferential inner surface25D, which is chamfered or beveled, extending from the cutting edge22, and a central cup-shaped surface24D that directs the tissue cut by the cutting edge22D into the tissue chamber12(seeFIG. 2). The cutting edge22D may be at a radially outer edge23D of the cutting element4D when the cutting element is in the cutting position. In one embodiment the cup-shaped surface24D may be a substantially smooth and continuous surface as described above in connection with the cutting element4. As disclosed in another embodiment below (FIGS. 19 and 20), the cup-shaped surface24D may be abrasive. In other embodiments, a through opening (not shown) may extend longitudinally through the cup-shaped surface24D to direct removed tissue proximally through the cutting element4D.

The raised elements26D extend generally longitudinally outward from the cup-shaped surface24B, within the internal cavity of the cutting element4D. The embodiment illustrated inFIGS. 12-18includes four raised elements26D, but the cutting element4D may include any number such as 1, 2, 3, 4, 6 or 8 raised elements. Each raised element26D is a small wedge of material that rises relatively abruptly from the inner surface (e.g., the cup-shaped surface24D) and which subtends an arc of about 1 to 30 degrees relative to axis LA, the four raised elements26D subtending an arc of about 4 to 60 degrees altogether. Referring toFIG. 13, each raised element26D has a leading radial wall (broadly, a first wall)30D, a trailing radial wall (broadly, a second wall)32D, a radially inner end wall34D (broadly, a third wall), and a distal wall (broadly, a fourth wall)38D. The leading radial wall30D has a depth extending longitudinally relative to the cutter4D between the distal wall38D and the cup-shaped surface24D, and a radial length RL (FIG. 15) extending generally inward from adjacent the cutting edge22D of the cutting element4D, as explained in more detail below. The leading radial wall30D is curved along its depth (i.e., curved longitudinally with respect to the cutting element4D) and is also curved along its radial length RL. A leading edge50D of the cutting element26D is defined at the intersection of the leading radial wall30D and the distal wall38D. The leading edge50D is curved radially relative to the cutter4D. In some embodiments the raised elements26D may occupy a relative small part of the cup-shaped surface24D and may be recessed from the cutting edge22D in the manner described above in connection with the cutting element4. In other embodiments at least 60%, 70%, 80% or 90% of the surface area of the cutting element is a smooth cup-shaped surface.

The distal wall38D of the cutting element4D forms an angle of less than 90 degrees with respect to the longitudinal axis LA. In some embodiments the wall38D is angled such that edge50D is more distal than the edge defined at the intersection of the distal wall38D and the trailing wall32D. The entire distal wall38D may adjacent to, but recessed longitudinally from, the cutting edge22D so that the distal wall is spaced a minimum longitudinal distance from about 0.0010 to about 0.0050 inch (0.0025 to 0.0127 cm), including about 0.0010, about 0.0020, about 0.0030, about 0.0040 or about 0.0050 inch (0.0025, 0.0051, 0.0076, 0.0101, or 0.0127 cm), from the cutting edge. The included angle between leading radial wall30D and the distal wall38D, in the vicinity of the leading edge50D, may be greater than 90 degrees. The cutting element4D is rotated in the direction R (FIG. 13) so that the leading edge50D engages the tissue to be removed. As shown inFIG. 15, the leading edge50D of the raised element26D may be spaced a radial distance d1measuring from about 0.0010 to about 0.0020 inch (0.0025 to 0.0051 cm) from the cutting edge22D. The raised elements26D may all be formed in the same manner or may be different from one another. The raised elements26D may also subtend different angles, be of different heights, have different radial lengths, or have a different spacing (including zero) from the cutting edge without departing from various aspects of the present invention.

Referring toFIGS. 14 and 15, the radial length RL of the leading radial wall30D of each raised element26D is defined by the radial distance between the radially outermost portion P1and the radially innermost portion P2of the leading radial wall. InFIG. 15, the radial length RL of the radial wall30D is measured using concentric, outer and inner imaginary circles C1, C2, respectively, each having a center that is coincident with the longitudinal axis LA. The radially outermost portion P1of the leading radial wall30D lies on the circumference of the outer imaginary circle C1, and the radially innermost portion P2lies on the circumference of the inner imaginary circle C2. In the illustrated embodiment, each radially outermost portion P1of the leading radial walls30D lies on the circumference of the same outer imaginary circle C1, and each radially innermost portion P2lies on the circumference of the same inner imaginary circle C2, though it is understood that the radially outermost and innermost portions, respectively, may not lie on the same imaginary circles without departing from the scope of the present invention. In the illustrated embodiment, the radially inner end wall34D is arcuately shaped so that substantially the entire radially inner end wall lies on the circumference of the inner imaginary circle C2, although this may not be the case in other embodiments. The radial distance between the circumferences of the outer and inner imaginary circles C1, C2, respectively, determines the radial length RL of the leading radial wall30D, as shown inFIG. 15. In one example, the radial length RL of the leading radial wall30D may measure from about 0.0050 in to about 0.0200 in, or from about 0.0075 in to about 0.0175 in, or from about 0.0100 in to about 0.0150 in. In one example, the radial length RL of the leading radial wall may be at least about 33%, or at least about 40%, or at least about 50%, or at least about 60% or at least about 70% or at least about 80% of the radius R (FIG. 15) of the cutting edge22D.

Referring still toFIG. 15, the radially innermost portion P2of the leading radial wall30D of each raised element26D is spaced a radial distance d2from the longitudinal axis LA of the cutting element4D. As set forth above, the radially innermost portion P2of the leading radial wall30D lies on the circumference of the inner imaginary circle C2. The radial distance between the longitudinal axis LA and the circumference of the inner imaginary circle C2determines the radial distance d2between the longitudinal axis and the radially innermost portion P2of the leading radial wall30D. In one example, radial distance d between the longitudinal axis and the radially innermost portion P2of the leading radial wall30D may measure from about 0.0150 in to about 0.0300 in, or from about 0.0175 in to about 0.0275 in, or from about 0.0200 in to about 0.0250 in. In one example, the radial distance d2may be less than about 66%, or less than about 60%, or less than about 55%, or less than about 50%, or less than about 45%, or less than about 40%, or less than about 35% of the radius R of the annular cutting edge22D, as shown inFIG. 15. In one example, the radial distance d2may be from about 15% to about 66%, or from about 20% to about 60%, or from about 25% to about 50%, or from about 30% to about 40% of the radius R of the annular cutting edge22D.

As disclosed above herein, in the deployed configuration the cutting element4D extends through the window or opening6in the tip18. In this embodiment, each raised element26D is configured such that as the cutting element4D is rotated 360 degrees, less than an entirety of the leading radial wall30D is ever exposed through the opening6. Stated another way, a radially outer portion of each raised element26D is cyclically exposed through the opening6while a radial inner portion of the leading radial wall never passes through the opening (i.e., is never exposed). This feature is shown inFIG. 17, where the circle indicated by reference character S defines an outer surface of the tip18that is immediately adjacent the window6(see also,FIG. 16). As can be seen fromFIG. 17, an imaginary line L is drawn to show the location where a radial portion of the cutting element4D is at its maximum exposure outside the catheter body. However, as can be seen from this figure, a radial inner portion of the leading radial wall30D of cutting element26D at the imaginary line L does not cross the exposure plane EP and does not pass through the window6.

The cutter4D is rotated in the direction of arrow R and pushed distally to force cup-shaped surface24D and raised elements26D into contact with material such as atheroma or plaque. Raised elements26D will tend to concentrate cutting force along edge50D because of the negative rake angle of the leading radial wall30D. Cutter4D will tend to scrape away material such as atheroma or plaque rather than cut into this material due to the obtuse included angle between wall30D and distal wall38D, in the vicinity of edge50D. Material contacted by raised elements26D will tend to be directed toward axis LA by surface30D which curves from a more circumferential extent near edge22D to a more radial extent near edge34D. Moreover, it is believed that configuring the raised element(s)26D so that only a portion of the leading radial wall30D intermittently passes through the window6(i.e., only a portion and not the entirety of the leading radial wall is exposed) and is intermittently exposed (as explained above), facilitates cutting and/or breaking of hardened tissue (e.g., calcified tissue) by ensuring that the raised elements26D engage tissue that may enter the window6, as shown inFIG. 18. The leading radial wall30D also more reliably guides or directs removed material toward the axis LA.

The cutting element4D may be formed in a suitable manner such as integrally as a single, one-piece construction. For example, the cutting element4D may be comprised of steel, tungsten carbide, tungsten carbide cobalt, tungsten carbide molybdenum, silicon carbide, silicon nitride, ceramic, amorphous metals or other materials and may be manufactured by methods including turning, grinding, sintering, electro-discharge machining (EDM), laser cutting, heat treating, precipitation hardening, casting or other methods.

Referring toFIGS. 19 and 20, cutting elements4E and4F are shown (respectively). Cutting element4E and4F include raised elements26E,26F, that may be identical to the raised elements26A-26D of any of the previously disclosed cutting element4A-4D disclosed above or have a different configuration. Accordingly, the teachings of the raised elements26A-26D set forth above are incorporated in this embodiment. As opposed to the previously disclosed cutting elements, the cutting elements4E and4F each has an abrasive cup-shaped surface24E,24F. In one embodiment, other than the abrasive cup-shaped surface24E,24F, the cutting elements4E and4F are identical to the cutting element4D, including the raised elements26E being identical to the raised elements26D. Accordingly, in this embodiment each of the cutting elements4E and4F includes the cutting element4D and the respective one of the abrasive cup-shaped surfaces24E,24F. Referring toFIG. 19, cutting element4E includes the embossed area of the cup-shaped surface24E, including raised, diamond-shaped abrading members100. Referring toFIG. 20, cutting element4F includes a dimpled area of the cup shape surface24F including depressed portions102. In each embodiment, the abrasive cup-shaped surface24E,24F abrades hardened tissue (e.g., calcified tissue), and in particular, the abrasive cup-shaped surface abrades hardened tissue that is not engaged by the raised elements26E. Thus, it is believed that the cutting elements4E and4F may more effectively remove hardened tissue compared to the cutting element4, which is free from an abrading surface.

The cutting elements4E and4F each may be formed integrally as a single, one-piece construction, or may be formed as a multiple-piece construction. As an example, each cutting element4E and4F may be comprised of steel, tungsten carbide, tungsten carbide cobalt, tungsten carbide molybdenum, silicon carbide, silicon nitride, ceramic, amorphous metals or other materials and may be manufactured by methods including turning, grinding, sintering, electro-discharge machining (EDM), laser cutting, heat treating, precipitation hardening, casting or other methods.

Referring toFIGS. 21-25, another embodiment of a cutting element is indicated generally at4G. The cutting element4G is similar to the cutting element4B, and therefore, like components are indicated by similar reference numerals, and the teachings set forth with respect to the cutting element4B apply equally to this embodiment. Briefly, each raised element26G of the cutting element4G has a leading wall30G, a radial inner end wall34G, a distal wall38G, and a leading edge50G. For purposes of this disclosure, the main difference between the present cutting element4G and the prior cutting element4B is that the radial distance between the leading edge50G of each raised element26G and the cutting edge22G of the present cutting element4G is greater than the radial distance between the leading edge50B of each raised element26B and the cutting edge22B of the cutting element4B. It is understood that the teachings set forth herein for the cutting element4G apply equally to the other cutting elements4A-4F.

In the illustrated example, the present cutting element4G includes an undercut (e.g., groove, recess, notch or cutout)106in each of the raised elements26G adjacent the cutting edge22G. The undercut106extends through the leading wall30G, the leading edge50G, and the distal wall38G of each raised element26G. The undercut106extends generally radially into the raised element26G at the radially outermost portion of the raised element. As best seen inFIG. 24, the undercut106has a circumferential extent almost perpendicular to the wall30G. The depth of the undercut106shallows slightly circumferentially away from the leading edge50G. In contrast, the undercut41C ofFIGS. 11 and 11Aextends circumferentially into the raised element26C and has a generally radial extent along the wall30C. As shown best inFIG. 25, because of the undercut106, the radially outermost portion P1of the leading edge50G of the cutting element4G is radially spaced from the chamfered circumferential inner surface25G (broadly, the inner surface) of the cutting element a radial distance D1(FIG. 25). In one example, the radial distance D1may measure from greater than 0.0000 in to about 0.0100 in, or from greater than 0.0000 to about 0.0050 in, or from about 0.0005 in to about 0.0015 in. The radially outermost portion P1of the leading edge50G is radially spaced from the cutting edge22G of the cutting element4G a distance D2, which is greater than the radial distance between the leading edge50B and the cutting edge22B of the cutting element4B. In one example, the distance D2may measure from greater than 0.0000 in to about 0.0100 in, or from greater than 0.0000 to about 0.0050 in, or from about 0.0005 in to about 0.0020 in. Moreover, the leading edge50G of the cutting element4G may be spaced a minimum longitudinal distance D3from the cutting edge22G. In one example, the distance D3may measure from about 0.0000 to about 0.0020 in. In one example, the leading edge50G is similar to the leading edge50B, except for the undercut106, and therefore, an imaginary extrapolated line extending from the leading edge50G intersects the chamfered inner surface25G of the cutting element4G at portion P3(FIG. 24), which may be substantially the same location as the radially outermost portion P1of the raised element26B (see, e.g.,FIG. 14).

It is believed that by spacing the leading edges50G of the raised elements26G from the chamfered inner circumferential portion25G of the cutting element4G, while maintaining a suitable minimum longitudinal distance between the cutting edge22G and the leading edges of the raised elements, the raised elements26G have better engagement with tissue than the cutting element4B, without sacrificing cutting efficiency of the cutting element.

The cutting elements4G may be formed integrally as a single, one-piece construction, or may be formed as a multiple-piece construction. As an example, the cutting element4G may be comprised of steel, tungsten carbide, tungsten carbide cobalt, tungsten carbide molybdenum, silicon carbide, silicon nitride, ceramic, amorphous metals or other materials and may be manufactured by methods including turning, grinding, sintering, electro-discharge machining (EDM), laser cutting, heat treating, precipitation hardening, casting or other methods.

Use of the catheter2is now described in connection with the cutting element4but is equally applicable to use of the catheter2with either the cutting element4A, the cutting element4B, or the cutting element4C. The catheter2is introduced into the patient in a conventional manner using a guidewire (not shown) or the like. The catheter2is advanced with the cutting element in the stored position ofFIG. 2until the catheter is positioned proximal to the location where material is to be removed. The cutting element4is then moved proximally so that the ramp16and cam surface14engage to move the cutting element4to the cutting position ofFIG. 3and to deflect the tip of the catheter2to move the cutting element4toward the tissue to be cut. The cutting element4is rotated about longitudinal axis LA and catheter2is then moved distally through the vessel so that the cutting element4cuts tissue. The tissue, which has been cut, is directed into the tissue chamber12by the cup-shaped surface24, one or more raised elements26, by curved surface30B (of cutting element4B), or by any combination of a cup-shaped surface, raised element, or curved surface. The location for collection of cut tissue may be other than described within the scope of the present invention.

More specifically, when using cutting element4B and rotating the cutting element in the direction of arrow R (FIG. 9) cutting edge22B slices softer material and cup-shaped surface directs the cut material into tissue chamber12; the relief angle assures that distally directed force on the catheter is concentrated at raised element edge50B rather than distributed over wall38B; raised elements26B will tend to scrape away or pulverize harder material such as calcium due to the obtuse included angle between leading radial wall30B and distal wall38B in the vicinity of edge50B; curved surface30B directs material particles towards cutter axis LA; and curved surface30B when rotating creates a fluid vortex that tends to direct material particles towards cutter axis LA and distally into tissue chamber12.

More specifically, when using an undercut such as that shown for cutting element4C and rotating the cutting element in the direction of arrow T (FIG. 11) undercut41C directs material away from cutting edge22A, along cup-shaped surface towards axis LA, and radially towards axis LA of the cutting element.

More specifically, when using the cutting element4D with raised elements26D having leading radial walls30D as set forth above, the raised elements facilitate cutting and/or breaking of hardened tissue (e.g., calcified tissue) by ensuring that the raised elements26D engage tissue that may enter the window6, as shown inFIG. 18.

When using the cutting elements4E or4F, the abrasive cup-shaped surface24E,24F abrades hardened tissue (e.g., calcified tissue), and in particular, the abrasive cup-shaped surface abrades hardened tissue that is not engaged by the raised elements26E.

When using the cutting element4G, the raised elements26G have improved engagement with tissue, as compared to the cutting element4B, without sacrificing cutting efficiency of the cutting element.