WO2008124567A1

WO2008124567A1 - Vascular thrombus extractor and extraction method

Info

Publication number: WO2008124567A1
Application number: PCT/US2008/059366
Authority: WO
Inventors: Alex Powell
Original assignee: Edwards Lifesciences Corporation
Priority date: 2007-04-05
Filing date: 2008-04-04
Publication date: 2008-10-16

Abstract

An extractor for vascular thrombus includes a guiding catheter with a cannula axially movable therein. The cannula includes a resilient basket fixed to the distal end thereof. The basket defines a cavity which is of increasing cross section greater than the cross section of the guiding catheter away from the distal end of the catheter when the basket is unconstrained. The basket is able to fit within the guiding catheter both before deployment and following acquisition of the vascular thrombus. The basket includes rods and flexible sheet material to define a radially compressible truncated conical cavity. An inflatable balloon is associated with the distal end of the guiding catheter. A port within the basket allows for the application of suction through the cannula to assist in the acquisition of vascular thrombus.

Description

VASCULAR THROMBUS EXTRACTOR AND EXTRACTION METHOD

RELATED PATENT APPLICATIONS

[0001] The present application claims priority under 35 U.S.C. Section

119(e) from U.S. Provisional Patent Application No. 60/910,446, filed April 5, 2007 and entitled "Vascular Thrombus Extractor and Extraction Method," the disclosure of which is incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

[0002] The field of the present invention is mechanical means and methods for the extraction of stationary vascular obstructive material. [0003] Techniques and instruments have been developed for use in the removal or repair of obstructive material in vessels and other body passageways. Such material includes thrombus forming into clots, either at a point of blockage or through migration to the point of obstruction as an embolus. Patents which discuss devices and methods for removal of emboli include United States Patent No. 5,800,457 to Gelbfish, which issued on Sep. 1 , 1998 and is entitled "Intravascular Filter and Associated Methodology"; United States Patent No. 5,836,968 to Simon et al., which issued on Nov. 17, 1998 and is entitled "Removable Embolus Blood Clot Filter"; United States Patent No. 6,231,544 to Tsugita et al., which issued on May 15, 2001 and is entitled "Cardioplegia Balloon Cannula"; United States Patent No. 6,312,407 to Zadno- Azizi et al., which issued on Nov. 6, 2001 and is entitled "Occlusion of a Vessel"; and United States Patent No. 6,702,782 to Miller et al., which issued on Mar. 9, 2004 and is entitled "Large Lumen Balloon Catheter"; and United States Patent No. 6,790,215 to Findlay, III et al., which issued on Sep. 14, 2004 and is entitled "Methods of Use for Percutaneous Material Removal Device and Tip." The contents of each of the aforementioned patents are hereby incorporated by reference in their entirety.

[0004] Fogarty embolectomy balloons and catheters have been shown to remove large amounts of thrombus and whole clots. However, such balloons and catheters require surgical exposure to remove clots from vessels. [0005] The technique of guiding catheter thrombectomy employs an end hole catheter or guide which is advanced to the thrombus with vigorous suction applied. This technique is frequently successful in placing the clot in attachment to the catheter/guide. However, the clot frequently is detached when the catheter/guide is retracted into the sheath. This is understood to occur because the clot is frequently larger than the sheath and the clot is sheared off upon withdrawal of the catheter/guide into the sheath.

[0006] Finally, wide mouth catheters have been considered. With such catheters, it is hoped to create a large opening into which the clot can be drawn. The mouth of the catheter would then collapse down on the clot and the clot can be removed therewith. Once the clot is retained, the entire device needs to be removed to clear the vessel. When the procedure is incomplete, i.e., when the clot remains or partially remains, an entire system must then reenter the target vessel before imaging or further clot removal can be performed. This cumbersome and time consuming approach is understood to have contributed to the lack of commercial availability of wide-mouth catheters for such procedures.

[0007] The deliberate fragmentation of vascular clots without effective capture and difficult placement and reentry can have adverse consequences and/or the need for cumbersome extended procedures. Conclusive procedures and facile reentry, where required, are greatly preferred.

SUMMARY OF THE INVENTION

[0008] The present invention is directed to both method and apparatus for the removal of whole clots without fragmentation and, where necessary, substantial thrombus with easy reentry to complete clot removal. A basket is inserted into a blood vessel from which a vascular clot is to be removed. The basket is collapsible upon acquisition of the whole clot or available thrombus for axial removal and, if necessary, facile reentry. [0009] In a first separate aspect of the present invention, the method includes inserting a basket into a blood vessel from which a clot is to be excised. The basket is collapsed to compress acquired thrombus, which may or may not be the entire clot. The basket is then withdrawn from the vessel longitudinally into a guiding catheter. [0010] In a second separate aspect of the present invention, the method includes inserting a collapsed basket into a blood vessel from which a clot is to be excised. The basket is then expanded and acquires thrombus and possibly a whole clot. The basket is then collapsed to compress acquired thrombus and withdrawn from the vessel axially through a guiding catheter. The expansion of the basket may be accomplished by extending the basket from the distal end of a catheter when adjacent the clot. The basket may be collapsed to compress acquired thrombus by drawing the basket back into the distal end of the catheter. [0011] In a third separate aspect of the present invention, the method includes inserting a basket in a guiding catheter into a blood vessel from which a clot is to be excised. The basket is extended to acquire thrombus and then retracted into the guiding catheter. The retraction into the guiding catheter compresses the basket and the thrombus therein. The basket can then be drawn through the guiding catheter for full extraction from the catheter. The procedure may then be undertaken again to acquire and remove remaining thrombus without having to reinsert the guiding catheter if the whole clot was not extracted in the first removal. [0012] In a fourth separate aspect of the present invention, an extractor includes a guiding catheter. A basket is fixed to and extends from a distal end of a long element and extends longitudinally of a guide lumen. The basket and element are able to move longitudinally through the guide lumen of a guiding catheter. When the basket is unconstrained, it defines a cavity which is of increasing cross section that is greater than the lumen of the guiding catheter. The basket is able to fit within the lumen when constrained by the guiding catheter.

[0013] In a fifth separate aspect of the present invention, a basket is provided on the end of a long element and extend longitudinally of the guide lumen to move longitudinally through the guiding catheter. The basket includes rods which extend from the distal end of the long element to cooperate with flexible sheet material between the rods. The resulting basket can be constructed to be fully expanded when in the unconstrained state. [0014] In a sixth separate aspect of the present invention, the acquisition of thrombus, either partial or whole clots, in any of the foregoing separate aspects may be by the application of suction through the center of the basket. [0015] In a seventh separate aspect of the present invention, any of the foregoing aspects are contemplated to be combined to greater advantage. [0016] Accordingly, it is an object of the present invention to provide an improved method and apparatus for the mechanical extraction of vascular thrombus and whole clots. Other and further objects and advantages will appear hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a side view of a cannula with a basket on the distal end thereof positioned in a guiding catheter. The view is partially broken away for clarity.

[0018] Figure 2 is a side view of the device depicted in Figure 1 with the basket partially retracted into the guiding catheter.

[0019] Figure 3 is a side view of a device according to an embodiment of the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0020] Turning in detail to the Figures, the extractor includes a guiding catheter 10 of conventional construction. The guiding catheter may be plain or may include other features such as multiple longitudinal lumens and balloons. A balloon 12 is provided at the distal end of the guiding catheter 10 in the present embodiment. A catheter with a balloon, and additional features not relevant here, is disclosed in U.S. Patent Application Publication No. 2004/0138614, the disclosure of which is incorporated herein by reference. The guiding catheter 10 has a guide lumen 14 extending fully through the catheter 10.

[0021] A long element in the form of a cannula 16 extends longitudinally through the guide lumen 14 to the distal end 18 of the catheter 10. The cannula 16 includes a flow lumen 20 therethrough. The cannula 16 is coaxially arranged with the guiding catheter 10 in the illustrated embodiment and can move longitudinally therein.

[0022] A resilient basket 22 is fixed at the distal end 24 of the cannula

16. The resilient basket 22 is defined by flexible sheet material 26 shown to be formed in a truncated conical shape. The material 26 may be either porous or nonporous depending upon the specific utility of the device. The sheet material 26 is flexible so that it may be retained in a radially compressed configuration within the guiding catheter 10. The sheet material 26 may also exhibit resilience to fully expand the basket 22 when unconstrained. [0023] Rods 28 are affixed to the material 26 to add structural integrity to the basket 22. The rods 28 are designed to pivot in a radial direction from a position substantially parallel to one another when collapsed within the guiding catheter 10 to the fully unconstrained truncated conical shape when extending outwardly of the guiding catheter 10. There may be any number of rods 28 but four to six are considered practical. The rods 28 may be attached to either side of the sheet material 26. Because of the interaction with the guide catheter 10, the rods 28 may best be placed on the outside of the sheet material 26 to ride on the distal end of the lumen 14 and to push the sheet material 26 from behind when compressing thrombus.

[0024] The truncated conical shape provides for the cavity defined within the resilient basket 22 to have an increasing cross section which is greater than the cross section of the guide lumen 14 away from the distal end of the guiding catheter. Other than a strictly conical shape may be employed as may be convenient such as when greater depth and cavity volume is desired with the outer periphery constrained to a practical maximum diameter. [0025] The rods 28 are configured to be sufficiently rigid that vascular thrombus contained within the cavity of the basket will be compressed as the rods are forced inwardly by the guiding cannula. The rods 28 may be straight or curved with the concavity facing inwardly of the basket 22 to increase cavity volume. The hinging of the rods 28 may be by mechanical hinges, living hinges or simply adherence to the flexible sheet material 26 which in turn provides the hinging action. The hinging of the rods 28 may contribute to the bias acting to expand the basket 22 to its fully open state when unconstrained. The sheet material 26 may preferably be bonded to the end of the cannula 16, integrally fabricated into the cannula 16, or even clamped or sewn in place. [0026] In operation, the extractor is assembled with the cannula 16 in the guiding catheter 10. The resilient basket 22 on the distal end of the cannula 16 is initially contained within the guiding catheter 10. In this configuration, the rods 28 are substantially parallel to one another with the flexible sheet material 26 folded by the radial compression.

[0027] The guiding catheter 10 is appropriately inserted into the targeted blood vessel 32 using conventional techniques such that the distal end 18 of the guiding catheter 10 comes into position adjacent the targeted vascular clot. Naturally, the proportions of the extractor and the components thereof are selected to meet the specific requirements of the targeted vessel and vascular clot. [0028] Once appropriately inserted, the extractor is manipulated to move the cannula 16 longitudinally to extend the basket 22 which is extending longitudinally of the guide lumen from the end of the guiding catheter 10. In this way, the basket 22 is expanded from a radially collapsed state to an unconstrained fully expanded state to the extent allowed by the vessel 32 adjacent to the clot. The foil expansion may be by the resilience of the material 26, the configuration of the rods 28 or additional spring elements associated with the rods 28. In the particular embodiment depicted in Figure 1, the basket 22 is expanded until it is adjacent to and/or contacts the walls of the blood vessel 32. [0029] The entire clot or portion thereof, either being made up of thrombus, is then acquired in the cavity of the basket 22. This acquisition may be through the axial movement of the basket 22. Alternatively, the port 30 defined by the flow lumen 20 of the cannula 16 which opens into the cavity of the basket 22 may be subjected to suction through the flow lumen 20. Such suction can draw vascular thrombus, typically the clot as one mass, into the cavity of the basket 22 for acquisition. Other elements for physically engaging the thrombus may be extendible through the flow lumen 20 to engage the clot to further assist retention by the basket or partial/complete extraction, with or without the suction. One such device is illustrated in U.S. Patent No. 6,790,215, the disclosure of which is incorporated herein by reference. [0030] With the acquisition of the thrombus, the cannula 16 is then drawn longitudinally relative to the guiding catheter 10 back into the guide lumen 14. Such movement relative to the blood vessel 32 may have the guiding catheter move forward or the basket move back or a combination of both. The technique may depend on the available movement of the clot or portion thereof. [0031] As the basket 22 encounters the rim of the distal end 18 of the guiding catheter 10, the basket 22 and the acquired thrombus therein are radially compressed. This compression continues until the basket 22 is withdrawn substantially fully into the guide lumen 14 of the guiding catheter 10. The withdrawal of the basket 22 may continue such that the longitudinally arranged and movable cannula 16 and basket 22 are drawn fully from the guiding catheter 10. A fresh cannula 16 can then be inserted for measurement or further thrombus extraction without withdrawing the guiding catheter 10. [0032] In circumstances throughout this procedure where blood flow through the surrounding vessel 32 is disadvantageous, the balloon 12 can be inflated until it is adjacent and/or contacts the walls of the blood vessel 32 to thereby prevent flow. The balloon 12 may also be used when suction through the cannula 16 is employed. This prevents flow around the basket 22 which might distort the basket 22 and/or frustrate efforts to reduce pressure in the blood vessel 32 and draw flow from the direction of the clot. With the guiding catheter retained in position within the vessel 32, the balloon 12 can prevent flow while multiple attempts to clear the entire targeted clot are made using multiple cannula 16.

[0033] As depicted in FIG. 3, a device 40 according to an embodiment of the present invention comprises an elongate flexible guiding catheter body 42 having a proximal end 44 and a distal end 46. At the distal end 46 of the guiding catheter body 42 is a distal material removal tip 48, such as depicted in FIGS. 1 and 2. A control 50 (which in the particular embodiment depicted is configured as a hand-held control) is attached to the proximal end 44 of the guiding catheter body 42 and permits manipulation of the system 40, which may include (by way of example) extension and retraction of the basket and rods (depicted as elements 22 and 28 in FIGS. 1 and 2, but not visible in the larger view of FIG. 3) into and out of the guiding catheter body 42. The control 50 may also permit manipulation of other elements of the guiding catheter body 42, including elements of the distal end 46 thereof. The control 50 may carry electronic circuitry, controls, and/or indicators. [0034] A vacuum source 52 may be secured to and communicating with the hand-held control 50, which may in turn include connecting passages through which the vacuum source 52 can create a negative pressure in the interior of the guiding catheter body 42 and/or interior of an elongate member (such as the cannula 16 depicted in Figures 1 and 2) passing within the interior of the guiding catheter body 42. The negative pressure thus created by the vacuum source 52 can provide suction at the distal end 46, such as at the port 30 through the flow lumen 20 of Figures 1 and 2. [0035] A drive motor (not shown) may be mounted within the hand-held control 50 for supplying longitudinal, rotational, or other motion to an elongated element (such as the cannula 16 from Figures 1 and 2) extending through the guiding catheter body 42. As was depicted in Figures 1 and 2, the cannula 16 or other elongate member may be hollow, thus permitting passage therethrough of a guidewire 54 which can extend through the distal material removal tip 48 as depicted in Figure 3.

[0036] Thus, an improved thrombus extractor has been disclosed along with an improved method for thrombus extraction. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention therefore is not to be restricted except in the spirit of the appended claims.

Claims

What is claimed is:

1. A method for removing thrombus from a blood vessel, comprising inserting a basket into the blood vessel axially in a guiding catheter; acquiring the thrombus in the inserted basket; collapsing the basket including compressing the acquired thrombus; withdrawing the basket with the compressed thrombus from the blood vessel longitudinally into the guiding catheter.

2. The method of claim 1, inserting the basket including the basket initially being collapsed, the method further comprising expanding the initially collapsed basket.

3. The method of claim 2, inserting the basket further including inserting the guiding catheter having a distal end, the initially collapsed basket being in the guiding catheter, expanding the inserted basket including extending the basket from the distal end of the guiding catheter.

4. The method of claim 3, collapsing the basket including retracting the extended basket into the distal end of the guiding catheter.

5. The method of claim 4, withdrawing the basket including fully extracting the collapsed basket from the guiding catheter with the guiding catheter remaining inserted.

6. The method of claim 4 further comprising blocking the blood vessel at the distal end of the guiding catheter including inflating a balloon.

7. The method of claim 1 further comprising blocking the blood vessel axially of the inserted basket.

8. The method of claim 7, blocking the blood vessel including inflating a balloon.

9. The method of claim 1, placing the thrombus including locating one side of the inserted basket adjacent the thrombus and sucking fluid from the one side through the basket.

10. A method for removing thrombus from a blood vessel, comprising inserting a basket into the blood vessel; blocking the blood vessel axially of the inserted basket; acquired the thrombus in the inserted basket including locating one side of the inserted basket adjacent the thrombus and sucking fluid from the one side through the basket; radially collapsing the basket including compressing the acquired thrombus; withdrawing the basket with the compressed thrombus longitudinally into the guiding catheter.

11. An extractor for thrombus from a blood vessel, comprising a guiding catheter including a distal end and a guide lumen; a long element including a distal end and being longitudinally movable within the guide lumen; a basket fixed to and extending from the distal end of the long element and extending longitudinally of the guide lumen at the distal end of the guiding catheter, the basket defining a cavity which is of increasing cross section greater than the cross section of the guide lumen away from the distal end of the long element when unconstrained, the basket fitting within the guide lumen when constrained by the guiding catheter.

12. The thrombus extractor of claim 11, the long element being a cannula and further including a flow lumen, the basket including a port at the distal end of the flow lumen for flow between the flow lumen and the basket cavity.

13. The thrombus extractor of claim 11 , the basket including rods mounted to and extending from the distal end of the long element and flexible sheet material at least between the rods.

14. The thrombus extractor of claim 13, the basket being fully expanded in the unconstrained state.

15. The thrombus extractor of claim 11 , the guiding catheter further including an inflatable balloon at the distal end thereof.

16. An extractor for thrombus from a blood vessel, comprising a guiding catheter including a distal end and a guide lumen; a cannula including a flow lumen and a distal end and being longitudinally movable within the guide lumen; a basket fixed to and extending from the distal end of the long element and extending longitudinally of the guide lumen at the distal end of the guiding catheter, the basket defining a cavity which is of increasing cross section greater than the cross section of the guide lumen away from the distal end of the long element when unconstrained, the basket fitting within the guide lumen when constrained by the guiding catheter, the basket including a port at the distal end of the flow lumen for flow between the flow lumen and the basket cavity, rods mounted to and extending from the distal end of the cannula and flexible sheet material at least between the rods, the basket being fully expanded in the unconstrained state.

17. The thrombus extractor of claim 16, the guiding catheter further including an inflatable balloon at the distal end thereof.