Device and method for centering and crossing vascular occlusion

Abstract

To provide a device and method for suitably centering and crossing a vascular occlusion.SOLUTION: A catheter for centrally crossing an occluded blood vessel includes a catheter body having a distal end, a proximal end, and a central passage. A rotatable drive shaft extends through the central passage and has a distal end, a proximal end, and a central lumen. A cutting tip is mounted on the distal end of the rotatable drive shaft and configured to cut through occlusive material when rotated. A plurality of spiral or other flat springs is disposed circumferentially about a distal portion of the catheter body to maintain centering of the catheter and form a passage as the catheter is advanced through a chronic total occlusion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of U.S. Provisional Application No. 62 / 465,108, filed Feb. 28, 2017 (Attorney Docket No. 46306 - 705.101) and U.S. Application No. 15 / 905,491, filed Feb. 26, 2018 (Attorney Docket No. 46306 - 705.201), the entire disclosures of which are hereby incorporated by reference herein.

Background Art

[0002] Chronic total occlusion (CTO) is a vascular lesion that blocks most or all blood flow through a blood vessel. CTO can occur in any of most blood vessels, including coronary arteries, carotid arteries, iliac arteries and veins, femoral arteries and veins, and popliteal arteries and veins. Usually, a CTO lesion will develop over a period of months to years. Due to this chronic pathology, there will usually be a sufficient amount of time with respect to the emergence of collateral blood vessels for supplying blood to tissues. However, these collateral blood vessels often fail to provide sufficient blood flow to keep the organ active and to support their proper function.

[0003] Over the years, many catheters have been proposed for the treatment of CTO. Of particular interest herein, U.S. Patent No. 9,060,806, invented by the inventors herein, describes a catheter. The catheter has a motor - driven or other rotatable distal cutter and a plurality of laterally deployable centering elements. While being very effective, the centering elements in this design are not always able to maintain centering when crossing a certain hard lesion, and the motor - driven or other rotatable distal cutter can also be difficult to control in some situations.

[0004] For these reasons, it would be desirable to provide an improved device and method for crossing an occlusion in a blood vessel or other embolism formed within a blood vessel to treat the occlusion and create a path for placement of a guide wire, intervention device, and catheter. In particular, it would be desirable to provide a thin device for creating a centered passage through the occlusion with a high degree of control over the advancement of the device and reduced resistance. Such a device should be relatively inexpensive to manufacture and relatively simple to use. At least some of these objectives will be achieved by the invention described below in this specification.

[0005] (2. Description of the Background Art) U.S. Patent No. 9,060,806 is described above. The following patents and published documents, namely, U.S. Patent Nos. 6,599,304, 7,763,012, 8,021,330, 8,062,316, 8,241,315, 8,361,094, 8,556,926, U.S. Patent Application Publication Nos. 2002 / 0128677, 2005 / 0038462, 2005 / 0171572, 2005 / 0216044, 2006 / 0074442, 2007 / 0083193, 2008 / 0281323, 2009 / 0270714, 2010 / 0082051, 2010 / 0168557, 2011 / 0022045, 2012 / 0253186, 2012 / 0283565, and 2014 / 0277009 are also of interest.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Means for Solving the Problems

[0007] In a first aspect, the present invention provides a catheter for transecting about an occluded blood vessel. The catheter comprises a tubular catheter body having a distal end, a proximal end, and a central passage therethrough. A rotatable drive shaft extends through the central passage of the tubular catheter body and has a distal end, a proximal end, and a central lumen therethrough. A cutting tip is mounted on the distal end of the rotatable drive shaft and is configured to cut through occluding materials such as plaque, calcified plaque, blood clots, thrombi, and equivalents when rotated. The cutting tip has a passage adjacent to the central lumen of the rotatable drive shaft. As will be described in detail below, the adjacent passage and lumen allow for the placement of a guide wire after the occlusion has been transected and a centered passage has been created through the occlusion.

[0008] The cross catheter of the present invention has a unique centering mechanism that accurately centers the distal region of the catheter as the cutting tip is rotated to create a passage through the vascular occlusion. The centering mechanism is particularly beneficial because it allows it to be pushed through the occluding material, engages the vessel wall, and provides a large circumferential surface area to minimize trauma, having a thin "cross-sectional" profile (circumferential width). More specifically, the centering mechanism comprises a plurality of leaf springs, typically helical leaf springs as described in more detail below, circumferentially disposed about the distal region of the tubular catheter body. The leaf springs are elastically self-expanding from a radially constrained configuration to a radially expanded configuration so that they can be deployed after the catheter has been advanced to a location near the occlusion within the target vessel. Each leaf spring has (1) a wide outer surface configured to engage the wall region of the vessel so as not to damage it and to center the tubular catheter body within the lumen of the vessel, and (2) a narrow distal edge configured to penetrate the occlusion as the catheter is advanced distally. In a specific embodiment, the leaf spring is cut from a tubular element such that the leaf spring is initially part of a cylinder and unfolds by expanding radially from the cylinder, extending radially outward in a helical pattern and engaging the vessel wall.

[0009] In a preferred embodiment of the present invention, the cutting tip is rotated by a manual mechanism, allowing the treating physician to manually control the cutting action of the tip while advancing the catheter containing portion. In particular, the physician can observe the progress of the cutting tip under fluoroscopy, and when combined with tactile feedback, the physician can manually control the advancement rate and the rotation rate of the cutting tip to optimally advance the catheter and create the desired central passage through the occlusion. For convenience, the cutting tip may be manually driven by a wheel or spindle located within the handle at the proximal end of the catheter.

[0010] The dimensions of the catheter are generally 120 cm to 150 cm in length and 5 Fr to 7 Fr in diameter (1 French (Fr) is equal to 0.33 mm), and the specific dimensions depend on the intended use of the catheter. For example, a catheter intended for the treatment of coronary arteries will typically have a length in the range of 130 cm to 150 cm and a diameter of about 5 Fr to 7 Fr. For peripheral devices, the tubular catheter body will typically have a length in the range of 120 cm to 140 cm and a diameter in the range of 5 Fr to 7 Fr.

[0011] The cutting tip may have various configurations. In particular, desirable is a cutting tip that includes at least one cutting loop, often two cutting loops, extending distally from the distal end of the cutting tip. For coronary applications, a single cutting loop may be radially offset from a guidewire port that is axially aligned with the passage through the cutting tip, or two cutting loops may be symmetrically disposed on opposite sides of the guidewire port. For peripheral applications, the cutting loop may be centered on the cutting tip, the passage through the cutting tip may be angled or radially offset from the central axis of the cutting tip and will direct the guidewire away from the cutting loop, or a pair of cutting loops may be symmetrically positioned on the cutting tip, similar to the coronary design.

[0012] In another aspect of the invention, a plurality of helical or other leaf springs may each have an Ω shape with a base attached to the tubular catheter body and a loop portion extending radially away from the tubular catheter body. In other cases, the plurality of helical leaf springs will consist of three helical leaf springs. In such cases, the three helical leaf springs will typically be spaced 120° apart circumferentially. For convenience, the helical leaf springs may be formed by laser cutting or otherwise patterning a tubular blank formed from an elastic material, typically an elastic metal, more typically a superelastic metal such as a nickel / titanium alloy (e.g., Nitinol® alloy).

[0013] In a second aspect of the invention, a method for transversely crossing a blocked blood vessel centered thereon includes advancing a catheter through an occlusion within the blood vessel. A cutting tip is rotated or vibrated in a rotational state on the distal end of the catheter so as to cut or abrade a passage through the occlusive material as the catheter is advanced. To center the catheter during the cutting procedure, a plurality of helical or other leaf springs are deployed or expanded from the distal portion of the tubular catheter body. The wide outer surface on each of the leaf springs engages without damaging the wall region of the blood vessel and aligns about the distal region of the catheter body within the lumen of the blood vessel, while the narrow distal edge of each of the leaf springs penetrates through the occlusion as the catheter is advanced and typically compresses and / or cuts a plaque or thrombus and enlarges the passage initially formed by the cutting tip.

[0014] In a specific embodiment of the method, the cutting tip is manually vibrated or rotated by rotating a cylinder or wheel on a handle, typically attached to the proximal end of the catheter. Deploying the plurality of helical leaf springs typically involves releasing the helical leaf springs from radial restraint so that they can elastically self-expand by advancing the distal portion of the catheter from a sheath or guide catheter that typically confines the helical leaf springs as a catheter prior to advancing the cutting tip through the occlusion.

[0015] In a more specific embodiment, the centering catheter may be used to place a guide wire through a passage created by the catheter. For example, the catheter may carry the guide wire for initial placement and optionally utilize it. The guide wire can also be used to assist in advancing the catheter across the occlusion. After the catheter has crossed the occlusion, the guide wire may be left in place through the occlusion for further intervention and / or advancement of diagnostic devices. However, in other cases, the centering catheter may be advanced up to but not through the occlusion and used as a platform for advancing the guide wire and other devices into the occlusion, and the centering catheter can provide an excellent platform for advancing tools into and / or through the center of the occlusion. In still other cases, a second guide wire may be exchanged for the initial placement guide wire when a guide wire with different characteristics is required.

[0016] In some cases, the catheter remains centered while a guide wire or other tool can be advanced and penetrated through the distal face of the inclusion. After penetration of the distal face, the cutting catheter can then be advanced. In yet other embodiments, the catheter can be advanced using a cutting tip until the proximal face of the occlusion is approached. However, before cutting through the proximal face of the occlusion, a guide wire can be deployed from the centering catheter and passed through the distal face of the occlusion. The cutting and centering catheter of the present invention is thus useful for a variety of specific protocols that require or benefit from central alignment of the catheter with the occlusion. The present invention provides, for example, the following. (Item 1) A catheter for transecting a blocked blood vessel at its center, A tubular catheter body, the tubular catheter body having a distal end, a proximal end, and a central passage therethrough. A rotatable drive shaft, the rotatable drive shaft extending through the central passage of the tubular catheter body and having a distal end, a proximal end, and a central lumen therethrough. A cutting tip, the cutting tip being mounted on the distal end of the rotatable drive shaft and configured to cut through an occlusion material when rotated, the cutting tip having a passage adjacent to the central lumen of the rotatable drive shaft. A plurality of leaf springs, the plurality of leaf springs being circumferentially arranged about the distal portion of the tubular catheter body and elastically self-expanding from a radially constrained configuration to a radially expanded configuration, each leaf spring having (1) a wide outer surface configured to engage the wall region of the blood vessel without damaging it so as to center the tubular catheter body within the lumen of the blood vessel, and (2) a narrow distal edge configured to penetrate the occlusion as the catheter is advanced distally. A handle at the proximal end of the tubular catheter body A catheter comprising. (Item 2) The catheter according to item 1, wherein the leaf spring is configured to self-expand in a helical pattern for transecting a blocked blood vessel at its center. (Item 3) The catheter according to item 1, wherein the tubular catheter body has a length in the range of 120 cm to 150 cm and a diameter of 5 Fr to 7 Fr for transecting a blocked blood vessel at its center. (Item 4) The catheter according to item 1, further comprising a manual rotation device attached to the rotatable drive shaft for transecting a blocked blood vessel at its center. (Item 5) The manual rotation device is a catheter for transecting around an occluded blood vessel according to item 3, comprising a rotating cylinder within the handle. (Item 6) The cutting tip is a catheter for transecting around an occluded blood vessel according to item 1, including at least one cutting loop extending distally from the distal end of the cutting tip. (Item 7) The at least one cutting loop extending distally from the distal end of the cutting tip is a catheter for transecting around an occluded blood vessel according to item 6, being radially offset from the passage within the cutting tip. (Item 8) The passage within the cutting tip is aligned with the central axis of the rotatable drive shaft, and the at least one cutting loop is radially offset from the central axis. It is a catheter for transecting around an occluded blood vessel according to item 6. (Item 9) The at least one cutting loop is aligned with the central axis of the rotatable drive part, and the passage within the cutting tip is radially offset from the central axis. It is a catheter for transecting around an occluded blood vessel according to item 6. (Item 10) The at least one cutting loop is aligned with the central axis of the rotatable drive part, and the passage within the cutting tip is radially offset from the central axis. It is a catheter for transecting around an occluded blood vessel according to item 6. (Item 11) The cutting tip is a catheter for transecting around an occluded blood vessel according to item 6, including at least two cutting loops extending distally from the distal end of the cutting tip. (Item 12) The cutting tip is a catheter for transecting around an occluded blood vessel according to item 1, having a grooved distal surface. (Item 13) The plurality of leaf springs each have an Ω-shaped outer shape with a base portion attached to the tubular catheter body, and a loop portion extending radially away from the tubular catheter body, for the catheter for transecting around an occluded blood vessel according to item 1. (Item 14) The plurality of leaf springs are composed of three leaf springs, for the catheter for transecting around an occluded blood vessel according to item 1. (Item 15) The three helical leaf springs are spaced 120° apart in the circumferential direction, for the catheter for transecting around an occluded blood vessel according to item 14. (Item 16) The rotatable drive shaft is axially translatable relative to the tubular catheter body such that the cutting tip and the tubular catheter body can be repositioned axially relative to each other, for the catheter for transecting around an occluded blood vessel according to item 1. (Item 17) The catheter according to item 16 further includes a thumb sliding portion on the handle for selectively repositioning the tubular catheter body relative to the handle and the rotatable drive shaft. (Item 18) A method for transecting around an occluded blood vessel, the catheter comprising: Advancing the catheter through the occlusion within the blood vessel; Rotating or vibrating in a rotating state the cutting tip mounted on the distal end of the catheter so as to cut through the occluding material as the catheter is advanced; and a plurality of leaf springs that: (1) as the catheter is advanced, engage the wide outer surface of each leaf spring against the wall region of the blood vessel so as not to damage it, to align the catheter within the lumen of the blood vessel; and (2) as the catheter is advanced, expand laterally outwardly to penetrate the narrow distal edge on each helical leaf spring through the occlusion to create a passage through the occlusion. (Item 19) Rotating or oscillating the cutting tip in a rotating state includes manually rotating or oscillating the tip, and is a method for transecting around an occluded blood vessel according to Item 18. (Item 20) Manually rotating or oscillating the tip includes rotating or oscillating a cylinder on a handle attached to the proximal end of the catheter, and is a method for transecting around an occluded blood vessel according to Item 19. (Item 21) The leaf spring includes a helical leaf spring, and the helical leaf spring self-expands from the distal portion of the catheter after releasing the leaf spring from radial restraint so that they elastically self-expand, and is a method for transecting around an occluded blood vessel according to Item 18. (Item 22) Releasing the leaf spring from radial restraint includes advancing the distal end of the catheter beyond the distal end of the guide catheter, and is a method for transecting around an occluded blood vessel according to Item 21. (Item 23) Further including pulling out the catheter and the cutting tip over a guide wire disposed within a central passage of the catheter and the cutting tip so as to leave the guide wire within the blood vessel lumen, and is a method for transecting around an occluded blood vessel according to Item 18. (Item 24) The catheter and the cutting tip are advanced completely through the occlusion prior to being retracted so as to leave the guide wire in a fixed position completely through the occlusion, and is a method for transecting around an occluded blood vessel according to Item 23. (Item 25) The catheter and the cutting tip are advanced partially through the occlusion prior to being retracted, and further includes advancing the guide wire through the remaining portion of the occlusion, and is a method for transecting around an occluded blood vessel according to Item 23. (Item 26) The method for transecting around an occluded blood vessel according to item 23, wherein the catheter and the cutting tip are advanced to the proximal surface of the occlusion prior to being retracted, and further including advancing the guide wire through the occlusion.

[0017] Citation by reference All published documents, patents, and patent applications referred to herein are incorporated herein by reference to the same extent as if each individual published document, patent, and patent application was specifically and individually indicated to be incorporated by reference.

Brief Description of the Drawings

[0018] The novel features of the present invention are specifically set forth in the appended claims. A deeper understanding of the features and advantages of the present invention will be obtained by reference to the following mode for carrying out the invention, which describes exemplary embodiments in which the principles of the present invention are utilized, and the following accompanying drawings.

[0019]

Figure 1

[0020]

Figure 2

[0021]

Figure 3A

[0022]

Figure 3B

[0023]

Figure 4

[0024]

Figure 5

[0025]

Figure 6

[0026]

Figure 7

[0027]

Figure 8

[0028]

Figure 9

[0029]

Figure 10

[0030] Referring now to FIG. 1, a catheter 10 for centering and transecting a vascular occlusion includes a catheter body having a distal end 12 and a proximal end 14 having a proximal handle 16 thereon. A rotatable cutting tip 18 is located at the distal tip of the distal end 12 and includes a single cutting loop 20 that can be rotated as described in more detail below. A centering cage 22 circumscribes the distal end 12 to maintain centering of the distal end 12 within the lumen of the blood vessel as the catheter 10 is advanced therethrough. In particular, the centering cage 22 includes a plurality of (three as shown) planar, generally helical leaf springs 24. The helical springs are preferably formed by cutting or otherwise patterning a cylindrical tube 26, and the entire tube may then be secured to the distal end 12 of the catheter 10. The cylindrical tube 26 is typically formed from Nitinol or other elastic metal and will be heat set such that the individual helical springs 24 are configured to expand radially therein in the absence of radial restraint such as a delivery sheath, guide catheter, or the like.

[0031] Referring now also to FIGS. 2 and 3A, the catheter 10 includes an outer shaft 30 and an inner drive shaft 32. The inner drive shaft 32 is concentrically disposed within the lumen passage of the outer shaft and is rotatable therein as will be described in more detail below. The inner drive shaft 32 also has a lumen 34 that houses a guide wire GW and is configured for other purposes such as the advancement of injection, aspiration, and other intervention tools.

[0032] The cutting tip 18 has a central passageway 36 that is aligned with and adjacent to the lumen 34 of the inner drive shaft. The central passageway 36 has a distal opening 38 through which a guide wire or other element, tool, or component can be advanced. The cutting tip 18 is fixedly attached to the distal end of the inner drive shaft 32 such that rotation of the inner drive shaft will effect rotation of the cutting tip 18 and the cutting loop 20. A retention ring 40 is provided for holding the inner drive shaft 32 within the central lumen passage of the outer shaft 30.

[0033] The central passageway 36 of the cutting tip 18 will typically be axially aligned with the lumen 34 of the inner drive shaft, but in other embodiments such as those intended for peripheral use as shown in FIG. 3B, the cutting tip 118 will have a centrally aligned cutting loop with a passageway 136 that is angled or offset with respect to its longitudinal axis such that the guide wire is deflected so that the distal opening 138 is away from the cutting loop 120. All other components and numbering shown in FIG. 3B are the same as those in the previous figures.

[0034] Referring now to FIG. 4, the catheter 100 according to the present invention may have an alternative cutting tip 118 design with pairs 20a and 20b of cutting loops disposed on either side of the distal guide wire port 112, typically symmetrically disposed about the port. Additionally, a plurality of longitudinal grooves 154 may be formed within the distal surface of the cutting tip 118 to facilitate cutting through plaque or thrombus as the catheter is advanced and the tip is rotated or vibrated in a rotational state. The centering cage 122 may be formed with a plurality of helical or other leaf springs 124 that radially expand outward as the catheter is advanced and have a plane 128 when engaged with the vessel wall. The centering cage 12 is similar to the cage 22 described above, but the cage 124 may have a shorter length to facilitate advancement through tortuous regions of the vasculature, particularly the coronary vasculature. The outer shaft 130 and the inner drive shaft 132 may have a configuration similar to or the same as that described above with respect to the outer shaft 30 and the inner drive shaft 32.

[0035] Referring now to FIGS. 5 and 6, when radially constrained, the helical centering spring 24 will generally be crushed within the envelope defined by the cylindrical tube 26, as shown in FIG. 5. In contrast, when released from the constraint, the three helical centering springs 24a, 24b, and 24c will each radially open to define a plane 28 having an effective diameter shown by the dashed line. The specific profile and plane defined by each of the helical centering springs can be determined by heat setting of Nitinol or other shape memory metal during the machining of the centering cage 22. Also, as observed in FIG. 6, the leading edge of each of the helical centering springs 24 has a very thin profile that allows the centering spring to be advanced through the occluding material with a reduced resistance to pushing.

[0036] The handle 16 is best illustrated in FIGS. 7 and 8. The handle 16 has a tip 42 attached to the proximal end of the outer shaft 30 of the catheter body. The outer shaft is fixedly attached such that the outer shaft will be prevented from rotating relative to the handle. In contrast, the inner drive shaft 32 is rotatably mounted within the handle 16 and is attached to a wheel or spindle 44 that allows for manual rotation of the wheel or spindle relative to the handle. Rotation of the wheel or spindle 44 will, in turn, rotate the inner drive shaft 32, which will, in turn, rotate the distal cutter 18 and the cutting loop 20. The proximal end of the inner drive shaft 32 (positioned adjacent to the wheel or spindle 44) passes through a bearing connector 48 and is received within a transition tube 46 that leads to a luer fitting 50 at the proximal end of the handle. The luer and transition tube are rotationally fixed within the handle, and the proximal end of the inner drive shaft 32 and the distal end of the transition tube 46 will form a rotary seal within the bearing connector. It is to be understood that guide wires and other intervening elements can be introduced through the luer 50 and the lumen of the inner drive shaft 32 such that they can be advanced out to the distal tip of the catheter and through the distal opening 38 of the cutting tip 18.

[0037] Referring now to FIGS. 9A - 9D, a catheter 10 for centering and traversing an occlusion may be advanced into a blood vessel BV through a chronic total occlusion CTO as shown. The distal end 12 of the catheter 10 is first advanced such that the cutting loop 20 is placed just proximal to the proximal surface of the chronic total occlusion CTO. The user then advances the catheter while manually rotating the cutting tip 18 and the cutting loop 20, penetrating through the proximal face of the occlusion and beginning to create a central passage therethrough. The helical centering spring 24 of the centering cage 22 engages the inner wall of the blood vessel as the catheter is advanced, maintaining the centering of the distal region 12 of the catheter. As described above, the plane of the spring engages the vessel wall so as not to damage it, while the narrow width of each spring allows the centering cage to pass through the occlusive material with reduced resistance. The catheter can be gradually advanced as the user manually rotates the cutting tip and observes the progress under fluoroscopy. This procedure can be completed when the distal tip of the catheter passes through the distal face of the occlusion as shown in FIG. 9C. After the catheter reaches the position shown in FIG. 9C, a guide wire GW may be inserted, the catheter 10 may be removed, and / or other interventional procedures may be performed.

[0038] Referring now to FIG. 10, the catheter 100 having the cutting tip 118 illustrated in FIG. 4 may be further modified to allow for axial advancement and retraction of the cutting tip relative to the centering cage 122. In particular, the thumb slide 160 may be positioned within a slot 164 in the wall of the handle 114, preferably distally relative to the wheel 144. The thumb slide is coupled to the outer member 130 such that, as indicated by arrow 162, by sliding the thumb slide axially, the outer member and the centering cage 122 attached distally thereto can typically be axially advanced and retracted over a range of 3 cm to 4 cm relative to the inner member 132 and the cutting tip 118, as indicated by arrow 164. The ability to decouple the distal section of the inner member shaft and the attached cutting tip 118 is a significant advantage when advancing the catheter through a tortuous vascular system such as the coronary vasculature, and the cutting tip and the distal inner member shaft are first advanced to pass through tight and / or narrow curves within the vascular system, and then the centering cage 122 may be advanced coaxially and separately over the inner member shaft.

[0039] Preferred embodiments of the invention are illustrated and described herein, but it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, modifications, and substitutions will occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. The following claims define the scope of the invention, and it is intended that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

1. A treatment catheter for use in treating an occluded blood vessel having plaque, the treatment catheter comprising: a tubular body having a distal portion; a rotatable drive shaft disposed within the tubular body; a distal tip having a cutting tip mounted on the distal tip and coupled to the rotatable drive shaft, the tubular body and the distal tip configured to be advanced through the plaque in the occluded blood vessel; a plurality of leaf springs forming a centering cage surrounding the distal portion of the tubular body of the treatment catheter, the centering cage configured to center the cutting tip in the occluded blood vessel, the cutting tip configured to cut the plaque when rotated or oscillated to create a passageway in the occluded blood vessel; and Equipped with the plurality of leaf springs are configured to be deployed laterally outward from the tubular body of the treatment catheter to engage a wall region of the blood vessel and maintain the centering of the cutting tip before the catheter is advanced through the plaque; As the catheter is advanced through the plaque, the leaf springs pass through the plaque and compress the severed plaque against the wall of the vessel to increase the diameter of the passageway while minimizing trauma to the vessel; Increasing the diameter of the passage widens the passage; the tubular body is configured to be withdrawn from the blood vessel after the passage is enlarged; A treatment catheter, wherein the diameter of the passageway does not decrease after the tubular body is withdrawn.

2. A therapeutic catheter as described in claim 1, wherein the plurality of leaf springs are arranged circumferentially around the distal portion of the tubular body, and each of the plurality of leaf springs has a wide outer surface configured to non-traumatically engage a wall region of the blood vessel so as to center the tubular body within the lumen of the blood vessel.

3. A therapeutic catheter as described in claim 1, wherein the distal tip is configured to cut the plaque by advancing the distal tip so that a distal edge formed by a narrow surface along the thickness of the plurality of leaf springs facing distally penetrates the plaque to expand the passage within the occluded blood vessel.

4. A therapeutic catheter as described in claim 1, wherein the plurality of leaf springs includes a plurality of spiral leaf springs.

5. A therapeutic catheter as described in claim 1, wherein the cutting tip comprises at least one cutting loop.

6. The treatment catheter is used to traverse through an interior of an occluded blood vessel, the occluded blood vessel comprising an occlusion comprising plaque; the centering cage is configured to center the distal tip of the treatment catheter in the occluded blood vessel; the cutting tip is configured to be rotated or rotationally oscillated to cut the occlusion and create a passageway through the occlusion as the tubular body and the distal tip are advanced; 2. The treatment catheter of claim 1, wherein the leaf springs are configured such that (1) a wide outer surface of each leaf spring atraumatically engages a region of the wall of the blood vessel so that the leaf springs center and align the catheter within the lumen of the blood vessel as the catheter is advanced, and (2) a distal edge formed by a narrowed surface along its thickness on each leaf spring facing distally deploys laterally outward from the tubular body proximal to the distal tip to penetrate the occlusion as the catheter is advanced.

7. A treatment catheter as described in claim 6, wherein the cutting tip is configured to be rotated or oscillated in a rotational state by manually rotating or oscillating the cutting tip in a rotational state.

8. A treatment catheter as described in claim 7, wherein manually rotating or rotatingly vibrating the tip includes rotating or rotatingly vibrating a cylinder on a handle attached to the proximal end of the treatment catheter.

9. A therapeutic catheter as described in claim 6, wherein the plurality of leaf springs includes a plurality of spiral leaf springs.

10. A therapeutic catheter as described in claim 9, wherein the helical leaf spring self-deploys from a distal portion of the tubular body of the catheter after the helical leaf spring is released from restraint such that the helical leaf spring elastically self-expands from a radially constrained configuration to a radially expanded configuration.

11. A treatment catheter as described in claim 6, further configured to be pulled over the guide wire positioned within the central passage of the treatment catheter so as to leave the guide wire within the lumen of the blood vessel.

12. The treatment catheter of claim 11, further configured to be advanced completely through the occlusion before being retracted to leave the guidewire in place completely through the occlusion.

13. The treatment catheter of claim 11, further configured to be advanced partially through the occlusion prior to being retracted, and the guidewire configured to be advanced through the remaining portion of the occlusion.

14. The treatment catheter of claim 11, further configured to be advanced to penetrate the proximal surface of the occlusion prior to being retracted, and the guide wire configured to be advanced through the occlusion.

15. A therapeutic catheter as described in claim 6, wherein rotating or rotatingly vibrating the cutting tip mounted on the distal tip of the catheter to cut the occlusion as the catheter is advanced enlarges the passage within the occluded blood vessel.

Images