Patent Application - MECHANICAL PUMP FOR REMOVAL OF FRAGMENTED MATTER AND METHODS OF MANUFACTURE AND USE > Description
This application is a continuation of U.S. patent application Ser. No. 10/797,482 (Attorney Docket No. 19744P-000620US), filed Mar. 9, 2004 which is a continuation-in-part of U.S. application Ser. No. 09/590,915 (Attorney Docket No. 19744P-000610US), filed Jun. 9, 2000 (now U.S. Pat. No. 6,702,830), which claims benefit under 35 USC 119(e) of U.S. Provisional Application No. 60/154,752 (Attorney Docket No. 19744P-000600US), filed on Sep. 17, 1999, under 37 CFR §1.78(a)(3). This application is also a continuation-in-part of U.S. patent application Ser. No. 10/680,367 (Attorney Docket No. 19744P-000420US), filed on Oct. 6, 2003, which is a continuation of U.S. patent application Ser. No. 10/162,276 (Attorney Docket No. 19744P-000410US), filed on Jun. 3, 2002 (now (U.S. Pat. No. 6,660,014), which is a continuation-in-part of U.S. application Ser. No. 09/454,517 (Attorney Docket No. 19744P-000400US), filed Dec. 6, 1999 (now U.S. Pat. No. 6,454,775), the full disclosures of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates generally to medical apparatus and methods and more particularly to devices and methods for removal of unwanted tissue such as thrombus, atheroma, fluid, polyps, cysts or other obstructive matter from body lumens, such as blood vessels, ureters, bile ducts or fallopian tubes.
Currently, there are many clinical approaches to removing unwanted material, many of which are performed surgically, wherein the treatment site is accessed directly through a surgical incision.
In recent years, a variety of catheter devices have been developed for use in intraluminal and intravascular procedures for fragmentation and removal of obstructive matter, such as blood clots, thrombus, atheroma, and the like, from blood vessels. More recently, devices that can be inserted percutaneously through a puncture in the skin have been developed to make the procedures less invasive. For example, a catheter device is inserted into a blood vessel at an access site located some distance away from the intended treatment site, and is then advanced through the vessel lumen until the treatment site is reached. In most instances this approach is performed “over-the-wire,” a technique that requires the physician to first place a guidewire device into the vessel lumen over which a larger catheter device can be tracked.
These techniques may employ various devices to fragment the unwanted clot or tissue from blood vessels such as rotating baskets or impellers as described in U.S. Pat. Nos. 5,766,191 and 5,569,275, cutters as described in U.S. Pat. No. 5,501,694, and high pressure fluid infusion to create a Venturi effect as described in U.S. Pat. No. 5,795,322. Other devices rely on the principles of the Archimedes-type screw, such as a one-piece solid machined screw to break up and/or remove clot.
In many instances, the luminal treatment techniques include infusing the vessel or treatment site with fluid (saline or a thrombolytic agent) to assist in breaking up the clot or tissue into a particle size that can then be aspirated through a lumen of the treatment device or using a secondary catheter hooked up to a source of vacuum/suction. Depending on the method of fragmentation and the consistency of the clot or tissue, the particle size can vary. If the material is not thoroughly fragmented, the larger particles can build up in the catheter and block the aspiration lumen.
While these catheters and techniques have been fairly successful, there is a need for improved devices for more efficiently evacuating fragmented material from the vessel or body lumen in order to overcome the difficulties of continued fluid infusion and material build up that blocks the aspiration lumen. Furthermore, it would be desirable to have devices that allowed aspiration of larger particles of fragmented material, thereby reducing procedure time. Preferably, such improved devices will have a low profile to enable percutaneous use, and will be flexible and torqueable to enable their use in tortuous lumens. Furthermore, such devices will preferably be designed to be placed over a guidewire and will be structured to mechanically translate and transport the fragmented material by directly pumping it through the catheter shaft. Optionally, the devices should include mechanisms for infusing materials, such as thrombolytic and other therapeutic agents, as well as disrupting the occlusive materials.
At least some of these objectives will be met by the design and use of the present invention.
2. Description of the Background Art
U.S. Pat. No. 5,556,408 describes an atherectomy cutter employing a vacuum source for removal of loose stenotic material and other debris from a vessel. Removal of thrombus by a rotating core wire on a drive shaft is described in U.S. Pat. No. 5,695,507 and fragmentation and removal of tissue using high pressure liquid is described in U.S. Pat. No. 5,795,322. U.S. Pat. No. 4,923,462 describes a coiled wire coated with Teflon and used as a drive shaft to rotate a catheter. Furthermore, U.S. Pat. No. 5,334,211 describes a coiled guidewire used to stabilize an atherectomy device. Patents describing atherectomy catheters with rotating helical pumping elements in U.S. Pat. Nos. 4,732,154; 4,886,490; 4,883,458; 4,979,939; 5,041,082; 5,135,531; 5,334,211; 5,443,443; and 5,653,696. A rotary thrombectomy catheter having an inner helical blade is commercially available under the tradename Straub Rotarex® from Straub Medical AG, as described in a brochure with a copyright of August 1999. Use and construction of the Straub Rotarex® also appears to be described in Schmitt et al. (1999) Cardiovasc. Intervent. Radiol. 22: 504-509 and in U.S. Pat. Nos. 5,876,414 and 5,873,882. Other patents of interest include U.S. Pat. Nos. 4,737,153; 4,966,604; 5,047,040; 5,180,376; 5,226,909; 5,462,529; 5,501,694; 5,569,275; 5,630,806; 5,766,191, 5,843,031; 5,911,734; 5,947,940; and 5,972,019; as well as published PCT applications WO 99/56801; WO 99/56638; and WO 98/38929. Motor drive units for catheters and other devices are described in U.S. Pat. Nos. 4,771,774 and 5,485,042.
According to the present invention, improved apparatus and methods are provided for transporting material between a target site in a body lumen of a patient and a location external to the patient. In some cases, the materials will be transported from the target site to the external location, which methods will generally be referred to as aspiration. In other cases, the material may be transported from the external location to the target site within the body lumen, which methods will generally referred to as infusion. In still other cases, materials may be simultaneously transported from the external location to the internal target site and transported away from the internal target site to the external location, referred to as circulation. In all cases, the material transport will be enhanced by rotation of an impeller disposed in a lumen of a catheter. The impeller will usually comprise a tubular or solid shaft having a helical rotor extending at least partially over an exterior surface thereof. Thus, rotation of the impeller will pump the material in the manner of an “Archimedes screw.”
In addition to such mechanical pumping, the methods and apparatus of the present invention may rely on supplemental pressurization of the catheter lumen being used to transport the material. In particular, for infusion, the liquid or other material to be introduced may be supplied under pressure, typically in the range from 0.1 psi to 10,000 psi, usually in the range from 5 psi to 350 psi. Conversely, in the case of aspiration, a vacuum may be applied to the catheter lumen, usually from 1 mmHg to 760 mmHg, usually from 5 mmHg to 760 mmHg.
The methods and apparatus of the present invention will be particularly suitable for use in medical procedures for removing occlusive and other substances from body lumens, such as blood clots, thrombus, and the like, from blood vessels. Catheters according to the present invention will be suitable for percutaneous introduction or introduction by a surgical cutdown to the blood vessel or other body lumen. Usually, the catheters will then be advanced to a remote target site where the treatment is performed. Preferably, the catheters of the present invention will be introduced over a guidewire in a so-called “over-the-wire” technique, although use of a guidewire will not always be required. Optionally, the apparatus of the present invention may be used in conjunction with a variety of other interventional catheters, particularly for intravascular treatments. For example, the material transport catheters of the present invention may be used to infuse thrombolytic and other therapeutic agents and/or aspirate fragmented clot, thrombus, and other occlusive materials in conjunction with angioplasty, atherectomy, laser ablation, embolectomy, endarterectomy and other known intravascular interventions. In particular, the material transport catheters of the present invention may be used in the procedures described in copending U.S. patent application Ser. No. 09/454,517, which has previously been incorporated herein by reference.
In a first aspect of the present invention, an over-the-wire material transport catheter comprises a catheter body having a proximal end, a distal end, and a lumen therebetween. An impeller is rotatably disposed in the lumen of the catheter body, and the impeller includes a tubular shaft having a central guidewire lumen therethrough. A helical rotor extends at least partially over an exterior surface of the tubular shaft, and it is intended that the material transport catheter be introduced over a guidewire in a conventional manner. Moreover, the impeller will usually be rotated over the guidewire, i.e., while the guidewire remains in place in the central guidewire lumen of the impeller, during use of the catheter for aspiration and/or infusion. Optionally, the material transport catheter may further comprise a material capture device, such as a funnel structure, a macerator, or the like, at or near the distal end of the catheter body. Alternatively, the distal end of the catheter body may be substantially free from surrounding structure so that a desired material may be infused and/or aspirated directly through one or more ports in the catheter body at or near its distal end.
In a second aspect, a selective infusion-aspiration catheter constructed in accordance with the principles of the present invention comprises a catheter body having a proximal end, a distal end, and a lumen therebetween. An impeller is rotatably disposed in the lumen of the catheter body, and a driver is provided which is coupleable to the impeller. By “coupleable,” it is meant either that the driver and impeller are permanently connected, or more usually, that the driver is a separate component but that the driver and impeller are adapted to selectively mate and permit the driver to rotate the impeller while the impeller remains disposed in the catheter body lumen. The driver will be adapted to selectively rotate the impeller in either a first direction to induce aspiration to the catheter body lumen or in a second direction to induce infusion through the catheter body lumen. In this way, the selective infusion-aspiration catheter can be used either for infusion or aspiration depending on the particular circumstances encountered. The selective infusion-aspiration catheter may further comprise a material capture device disposed at or near the distal end of the catheter body, such as a funnel structure, a macerator, or the like. Alternatively, the distal end of the catheter body may be substantially free from surrounding structure so that material may be aspirated and/or infused through one or more ports located at or near the distal end of the catheter body.
In a third aspect of the present invention, a circulation catheter comprises a catheter body having a proximal end, a distal end, and at least one lumen extending between the proximal end and the distal end. A first impeller is arranged in a lumen of a catheter body to aspirate materials from the distal end to the proximal end of the catheter body when the impeller is rotated. A second impeller is arranged in a lumen of the catheter body to infuse materials from the proximal end of the catheter body to the distal end of the catheter body when the second impeller is rotated. Since the circulation catheter includes two separate impellers, it is possible to rotate the impellers simultaneously so that material can be infused to a target location within a body lumen and simultaneously aspirated from that target location. For example, the circulation catheter may be used to introduce thrombolytic or other therapeutic agent to a blood vessel and to simultaneously or sequentially remove the lysed clot, thrombus, and other materials from the blood vessel. Suitable thrombolytic and other agents include GPIIIb/IIa antagonists, tissue plasminogen activator (tPA), calcium dissolving agents, urokinase (proUK), heparinized saline, and the like. Other therapeutic agents include fibrinolytics, anti-coagulants, antiplatlet drugs, anti-thrombin, gene therapy agents, chemotherapeutic agents, brachytherapy agents, and the like. Optionally, the first impeller and second impeller may terminate at spaced-apart ports along the length of the catheter body so that the thrombolytic or other agent will be assured of having a minimum residence time within the blood vessel prior to being aspirated. Further optionally, the first impeller and second impeller may be disposed in separate lumens within the catheter body. In such cases, both impellers will usually comprise a tubular or solid shaft having a helical rotor formed over the outer surface thereof. Rotation of the shaft thus selectively infuses or aspirates material through the associated catheter lumen. Alternatively, the first and second impellers may comprise a common tubular shaft where a first helical rotor is mounted over the exterior surface and a second helical rotor is mounted over an interior surface of the shaft lumen. By counterwinding the two helical rotors, it will be appreciated that the outer rotor will transport material in a first direction while the inner rotor transports the material in opposite direction. Thus, material may be infused through the annular lumen formed between the outside of the tubular shaft and the catheter body lumen and aspirated back through the interior of the tubular shaft, or vice versa.
As with the prior embodiments, the circulation catheter may further comprise a material capture device disposed at the distal end of the catheter body, such as a funnel structure, a macerator, or the like. Alternatively, the catheter body may be substantially free from surrounding structure.
In a fourth aspect of the present invention, a mechanical pump for use in a medical device comprises an elongate hollow, flexible inner tube having a proximal end, a distal end, and a central guidewire lumen. A first coiled (helical) rotor element having a distal end and a proximal end is disposed over an outer surface of the inner tube. A jacket secures the coiled rotor element to the outer surface to complete the mechanical pump.
The mechanical pump structure may then be used in the lumen of a catheter body or elsewhere in order to provide a pumping action in the manner of an Archimedes screw. Preferably, the inner tube has an outer diameter in the range from 0.5 mm to 5 mm, usually from 1 mm to 2 mm. The assembled coiled rotor will have a width in the diameter from 0.5 mm to 10 mm, preferably from 0.5 mm to 3 mm, and a pitch over the inner tube in the range from 1 turns/cm to 50 turns/cm, preferably from 3 turns/cm to 10 turns/cm. Optionally, the mechanical pump may further comprise a second coiled rotor element disposed over an inner surface of the central lumen of the inner tube. The first and second coiled rotors will usually be counterwound so that the pump may direct flow in both a distal direction and aproximal direction when the inner tube is rotated in a single direction. Alternatively, the first and second coiled rotors may be co-wound so that the pump may provide an increased flow through a catheter lumen when the pump is rotated in either direction. In a particular aspect of the present invention, a distal portion of the coiled rotor may be unattached to the outer surface of the inner tube so that said unattached portion forms or provides a “whip” element as the pump is rotated. The whip element will be suitable for mechanically disrupting clot, thrombus, or other occlusive materials when the pump is rotated in a body lumen. Alternatively, the whip may be used to mix the thrombolytic or other agents (as set forth above) which are being introduced by the pump in a blood vessel or other body lumen.
The mechanical pump just described may be fabricated by providing a hollow flexible tube, placing a resilient coiled rotor over an outer surface of the tube, and forming a jacket over at least a portion of the outer surface of the tube. In this way, the coiled rotor is secured to the outer surface of the flexible tube. Such a fabrication method is inexpensive and provides a high quality product. Placing the resilient coil over an outer surface of the inner tube may comprise winding the coil over the surface to successively place individual turns of the coil as the inner tube is rotated. Alternatively, a pre-formed coil may be partially “unwound” to increase its diameter and permit the coil to be located over the exterior surface of the inner tube. When in the proper location, the coil may be allowed to rewind over the surface to provide an interference fit. The interference fit can be enhanced by heating the wire. Preferably, the coil is then secured to the outer surface of the inner tube by forming or placing a jacket over the structure. For example, the jacket formed by dip coating the assembly of the tube and rotor(s) into an appropriate curable liquid polymer, such as nylon, polyurethane, polyimide, polyamide, PTFE, FEP, and the like. The coating can then be heated and/or radiation cured to induce cross-linking. Further, alternatively, the jacket may be placed by providing a heat shrinkable polymeric tube or sleeve, placing said rube or sleeve over the combination of inner tube and helical rotor, and then shrinking the jacket over the inner tube and coiled rotor to hold the two together. Further alternatively, the jacket may be formed by extruding a polymeric material directly over the inner tube and coil, or by vapor deposition or spray coating. In an alternative embodiment, the coil may be attached to the inner tube by an adhesive.
The present invention still further comprises methods for transporting materials between a target site in a body lumen of a patient in a location external to the patient. The distal end of the catheter is introduced to the target site over a guidewire. First impeller is rotated over the guidewire within a lumen in the catheter to transport material between the distal end of the catheter and a proximal end of the catheter. The material may be selectively transported in a first direction by rotating the impeller for aspiration, and a vacuum may be applied to the lumen of the catheter to assist in transporting material from the distal end. Alternatively, the impeller may be selectively rotated to transport material from the proximal end of the catheter through the catheter lumen to the distal end of the catheter, e.g., to infuse materials. In such instances, the materials may be provided to the catheter lumen under pressure to assist in transporting the material through the catheter lumen to the distal end of the catheter.
In some instances, the direction in which the impeller is rotated may be changed. Thus, at one time, the impeller may be rotated in a first direction to infuse materials to the target site within a body lumen. At a subsequent time, the impeller may be rotated in the opposite direction to remove or aspirate materials from the same target site.
In still another instance, a second impeller may be provided in the catheter and rotated to selectively transport material between the proximal end of the catheter and the distal end of the catheter. By simultaneously rotating the first impeller to transport material in an opposite direction, a circulation of material may be established.
In still another instance, first and second impellers may comprise counterwound helical rotors mounted on a common tubular member. In such an instance, rotation of the tubular member in one direction will cause a first rotor to infuse materials to the target site while the second rotor aspirates materials from the same target site. In all instances, infusion and aspiration may be assisted by applying pressure or a vacuum, as appropriate. The first impeller will conveniently be mounted on the outside of the tubular member, e.g., by any of the methods described above for placing a coiled rotor over a shaft member. The second impeller will usually be in the form of a helical rotor disposed within the lumen of the tubular member. The helical rotor may be “wound down” to assume a low profile, inserted into the tubular member lumen, and then allowed to unwind to provide an interference fit with the lumen wall. The coil may be further secured or attached to the lumen wall by any of the methods described above.
In still another aspect of the present invention, a method for selectively infusing and aspirating materials between a target site in a body lumen or patient and the location external to the patient, comprises introducing a distal end of the catheter to the target site. An impeller within the lumen of the catheter is rotated in a first direction to infuse material to the target site. Sequentially, the impeller is rotated in a second direction to aspirate material to the target site. Such infusion and aspiration can be particularly useful with the delivery of thrombolytic agents to blood vessels and the removal of lysed clot from those blood vessels.
In yet still another aspect of the present invention, a method for circulating materials through a target site in a body lumen of a patient comprises introducing a distal end of the catheter to the target site. A first impeller within the lumen of the catheter is rotated to transport material to the target site. A second impeller within a lumen of the catheter is rotated to transport material away from the target site. The first and second impellers may be located within separate lumens within the catheter, or alternatively, may be located within the same lumen within the catheter. In latter case, first and second impellers will usually comprise a flexible inner tube having a first helical rotor formed over an outer surface thereof and a second helical rotor formed over an inner luminal surface thereof. The first and second helical rotors are counterwound so that rotation of the inner tube in one direction will cause flow over the tube in a first direction and flow through the tube in the opposite direction.
In particular, the present invention provides an elongate mechanical pump component that can be used in an aspiration catheter as a stand alone device, or as part of the shaft construction of a therapeutic device to remove the material fragmented by the working end of the therapeutic device. The mechanical pump component is hollow, forming a guidewire lumen to allow it to be compatible with use over a guidewire, or with devices requiring a guidewire.
In an exemplary embodiment the pump device is formed from a resilient wire coil, wound along the length of a hollow flexible polymer tube, and bonded or attached thereto by an outer polymer coating that cross links or heat bonds to the inner tube. The coil member can be of various geometric cross sectional shapes. The outer polymer coating is preferably made of a thinner wall plastic than the inner hollow tube to assist in the attachment process. The thin wall coating also allows the struts of the coil member to protrude from the surface of the inner tube which, when rotated, provide the pumping action.
The present invention may also incorporate an outer sheath surrounding the mechanical pump to form a catheter device. The catheter device would be attached to a rotating motor drive unit (MDU) at the proximal end allowing the mechanical pump component to rotate at varying speeds, while the catheter sheath remains stationary. Optionally, the MDU can selectively drive the pump element in a clockwise or counterclockwise direction relative to the longitudinal axis of the device. In use, any material to be removed is evacuated through the annular space between the mechanical pump and the outer sheath and is moved proximally by the rotating coils of the mechanical pump.
In another aspect of the invention, a circulation catheter having a clearing element is disclosed. The catheter generally comprises: a catheter body having a proximal end, a distal end, and a lumen therebetween, the lumen forming a distal opening at the distal end of the catheter body; an impeller rotatably disposed in the lumen of the catheter body to aspirate materials from the distal end to the proximal end of the catheter body; and a clearing element disposed at the distal opening of the catheter body to prevent the materials from accumulating at the distal opening. In general, the clearing element spins relative to the catheter body to clear the distal opening of the catheter body as the shaft is rotated.
The circulation catheter may further comprise a material capture device, such as a macerator disposed at the distal end of the catheter body. In some embodiments, the macerator comprises a distal end and a proximal end, wherein the proximal end of the macerator extends into the distal opening of the catheter body to form the clearing element.
In another embodiment, the clearing element comprises a cutting member coupled to the impeller at or near the distal opening. The cutting member may be attached to the proximal end of the macerator. Alternatively, the cutting member is attached to a shaft coupled to the impeller.
In one aspect of the invention, a method for transporting materials between a target site in a body lumen, and a location external to the patient comprise: introducing a distal end of a catheter to the target site; rotating an impeller within a lumen of the catheter to aspirate material from the target site; and clearing an opening of the lumen at the distal end of the catheter body to prevent the material from accumulating at the opening.
Generally, clearing the opening comprises rotating a clearing element inside the distal opening of the catheter body. In some embodiments, the impeller has shaft and a helical rotor, wherein rotating the impeller further comprises rotating a macerator attached at a distal end of the impeller shaft, and wherein clearing the opening of the lumen comprises spinning a proximal end of the macerator inside the distal opening of the catheter body.
In another embodiment the clearing element is coupled to the impeller, and the clearing element is spun inside the distal opening of catheter body as the impeller is rotated to clear the opening of the lumen. The clearing element may comprises a cutting disk that is attached to the shaft or rotor of the impeller or the proximal end of the macerator.
An exemplary material transport catheter in the form of a mechanical aspiration device constructed in accordance with the present invention is illustrated in
As shown in
Referring now to
In operation, as depicted in
Detailed construction of an exemplary impeller 30 is shown in
Resilient coil 34 may be a single filament structure, a multiple filament structure, a plurality of filaments, a multi-filar structure, or the filaments may be a round wire, a ribbon wire, or a wire having an irregular cross-section, further where the filaments may have the same diameter, different diameters, and/or may be stacked. The coils will usually be a metal, but could also be formed from a variety of polymers. The exemplary coil 34 is formed of a round wire, preferably an 0.014 inch (0.36 mm) diameter 304 stainless steel wire, but can also be formed from Nitinol® alloy (NiTi), Elgiloy® or Titanium. Alternatively, it could be formed from a high durometer polymer or polymer fiber with a higher melt temperature than inner tube 32, such as PEEK or Kevlar®. In an alternative embodiment, coil 34 may have a geometric cross sectional shape other than round, such as oblong, triangular, or square.
The pitch of the resilient coil 34 can also be defined in terms of the distance between successive turns of the coil or still further alternatively, as the “turns/cm.” A table setting forth all the pertinent dimensions of the exemplary impeller 31, including the alternative pitch dimensions, is set forth below.
As illustrated in
Alternatively, the outer jacket 36 may be formed by other conventional techniques, such as heat shrinking a polymeric sheath or tube over the assembly of the inner tube 32 and coil 34, where the sheath material may be the same as or different than the underlying tube 32. Heat shrinking of a jacket would be particularly effective if the tube 32 is formed from a non-polymer, such as a shape memory metal alloy. In some cases, it might also be possible to extrude or spray the outer jacket 36 over the assembly of the inner tube 32 and rotor 34.
An impeller 400 (
Referring now to
Referring now to
Impeller 60 has other advantages. By providing for bi-directional flow using a single impeller, circulation and recirculation of materials to a target site within a patient body lumen may be achieved. For example, a thrombolytic agent could be introduced through the central lumen 68 of the impeller 60 while lysed clot, thrombus, or other occlusive materials are aspirated from the same target location in the annular lumen formed over the impeller. Other uses and advantages of the system will also be found.
The distal section 116 of the clot disruption catheter 112 is best illustrated in
The body of clot disruption catheter 112 will have a lumen 130 extending from hub 118 to the distal section 116, and the tubular shaft 122 will be disposed within the lumen 130. A distal end 132 of the tubular shaft 122 will be connected to the nose cone 128, and the shaft will preferably have an inner lumen 134 which terminates in a series of infusion ports 136 (which may be circular, as illustrated or may be elongate slits or may have a variety of other geometries) disposed between the distal end of the body of catheter 112 and the nose cone 128. The lumen 134 and infusion ports 136 will be useful, for example, for delivering thrombolytic and other agents used in connection with clot disruption. The lumen will also be able to receive a guidewire 120 (not shown) which exits through distal port 135 to facilitate positioning within a blood vessel or other body lumen.
Macerator 140 is disposed on the tubular shaft 122 within the expansible cage 126. The macerator 140 is illustrated as a helical wire or filament, but could comprise a variety of other structures. Helical wire 142 is formed from spring material, typically a spring stainless steel or shape memory alloy, and is fixedly attached to the shaft 122 at both ends. First attachment point 144 is visible in
Macerator 140 comprising helical wire 142 is intended to operate by rotation of the shaft 122. When the shaft 122 is rotating, the helix will trace a generally ovoid shell within the expansible cage 126, thus engaging and disrupting occlusive material which is within the cage. Optionally, although not necessarily, the macerator 140 may be configured to engage at least a portion of an inner surface of the expansible cage 126. In particular, when treating clot within blood vessels, the helical wire 142 will disrupt the clot and engage and entangle materials within the clot, particularly fibrin fibers which make up a substantial portion of the clot material. By breaking up and engaging the clot in this fashion, the clot is pulled away from the blood vessel wall rather than sheared from the wall as in many prior thrombectomy and atherectomy procedures. In particular, the combination of the expansible positioning cage 126 and the macerator which is spaced radially inward from the shell defined by the cage, clot removal and disruption can be performed with minimum risk of injury to the blood vessel wall.
The expansible cage 126 and macerator 140 will usually be radially collapsed to facilitate introduction and withdrawal of the catheter 112 to and from a target site within the vasculature or other body lumen. The necessary radial constraint can be provided in a number of ways. For example, a tether or filament could be wrapped around both the cage 126 and the macerator 140, with the constraint being removed when the device reaches the target site. Alternatively, the cage 126 and/or the macerator 140 could be composed of a heat memory material, permitting deployment by use of an induced temperature change, e.g., by passing an electrical current through the structures or by infusing a heated or cooled fluid past the structures. Preferably, however, a radial constraint will be provided by a sheath 146 which can be axially advanced to radially collapse both the cage 126 and macerator 140.
The catheter 112 further comprises a mechanical pump to assist in the removal of disrupted clot and other debris which is produced by operation of the macerator. The mechanical pump may comprise a helical rotor 148 which is disposed over the outer surface of the tubular shaft 122, as illustrated in both
Referring now to
Referring now to
Referring in particular to
The clot disruption catheter 200, the clot includes a mechanical pump component to assist in extraction of clot or other disrupted materials through the lumen of the catheter. As best seen in
An additional exemplary clot disruption catheter 300 is illustrated in
The funnel will usually be formed from a flexible filter material and supported on a plurality of rods 306 which can be actively or passively deflected in order to open or close the conical cage. Most simply, the rod members 306 will be resilient and have a shape memory which opens the cage structure in the absence of radial constraint. Thus, catheter 300 may be conveniently delivered through a sheath, in a manner analogous to that described in connection with
The proximal portion 320 of the macerator 316 will comprise a helical rotor 322 to form an impeller as described in connection with previous embodiments of the material transport catheters of the present invention. The impeller will act to assist in the aspiration of materials macerated by the macerator 310 and collected in the funnel 304, typically in combination with application of a vacuum at the proximal end of the catheter 300 (not shown).
Referring now to
Turning now to
Now referring to
The circulation catheter may further comprise a material capture device, such as a macerator 418 disposed at the distal end of the catheter body 412. The distal end of the macerator 418 is fixed to the shaft 424 at the catheter tip 420. The proximal end of the macerator 418 may extend unattached into the distal opening 414 of the catheter body to form the clearing element 410. In general, the clearing element 410 spins relative to the catheter body 412 to clear the distal opening 414 of the catheter body as the shaft 424 is rotated. The catheter 400 may also have an expansible cage 26 surrounding the macerator 418, wherein the macerator 418 engages the expansible cage as it is rotated.
Now referring to
While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.