# Patent

## Title
Reentry catheter and method thereof

## Abstract

The invention generally relates to method and apparatus for crossing an obstruction in a tubular member, and more particularly to a medical device method for crossing of a chronic occlusion in a subintimal or interstitial space of an artery.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation application of U.S. patent application Ser. No. 13/229,378, filed on Sep. 9, 2011, and allowed on Sep. 9, 2014, which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/503,477, filed on Jun. 30, 2011, both of which are hereby incorporated by reference in their entirety and for all purposes.


FIELD
The invention generally relates to method and apparatus for crossing an obstruction in a tubular member, and more particularly to a medical device method for crossing a chronic occlusion in a subintimal or interstitial space of an artery.
BACKGROUND
Atherosclerosis is a common human ailment arising from deposition of fatty-like substance, such as atheroma, or plaque on the walls of major blood vessels. These deposits occur within the peripheral arterial system which feeds the limbs of the body and also occur within the coronary arterial system which feeds the heart. These deposits accumulate in localized areas, narrow the vascular lumen, and eventually causing restriction of normal blood flow. In some cases, the deposits result in a chronic partial or total occlusion. Such restriction can lead to a serious health risk including critical limb ischaemia. If blood flow cannot be adequately restored through surgical or endovascular intervention and the probability of limb amputation increases dramatically.
Until recently, chronic total occlusions have been treated by bypass which poses high procedural risks and is quite traumatic to the patient. Recently, catheter based intravascular procedures have been utilized. These techniques include step-by-step crossing of an occlusion using Excimer laser atherectomy devices and methods, crossing the occlusion with highly flexible and maneuverable guide wires, and other techniques known in the art. Once the lesion has been crossed, then standard endovascular devices such as laser atherectomy, angioplasty, stenting, and the like, can be used to enlarge the lumen and increase blood flow within the peripheral arterial system. These catheter-based intravascular procedures are typically preferred since they are much less traumatic to the patient, safer and cost-effective while delivering comparable long term vessel patency compared to more traumatic surgical alternatives.
Before catheter-based treatments can be used, with the exception of step-by-step Excimer laser methods, the guide wire must first pass through the total occlusion to provide access for the interventional catheter. Specifically, once a guide wire has crossed the occlusion, it can then be used as a rail to support interventional catheters. In some cases, the physician can maneuver the guide wire through the total occlusion establishing access. In many instances, the physician encounters a calcified cap on the proximal end of the occlusion and is unable to maneuver the guide wire through the cap and across a calcified or fibrous lesion. In many cases, the guide wire inadvertently penetrates the subintimal space between the intimal layer and the adventitial layer of the blood vessel as the guide wire attempts to cross the lesion. Once in the subintimal space, it is difficult to direct the guide wire back into the vessel lumen making it nearly impossible to perform a catheter based intravascular procedure.
In one related art technique, Dr. Bolia developed a revasculature procedure as described in Recanalisation offemoro-popliteal occlusions: Improving success rate by subintimal recanalisation, Clinic Radiol, 40:325, 1989, by exploiting the subintimal space where a guidewire enters the subintimal space between the intima and adventitia layers, is subsequently advanced to a point distal to the occlusion, and then maneuvered to re-enter or puncture the vessel layers to enter the true lumen of the vessel. Once the guide wire has traversed through the subintimal layer and re-enters the true lumen of the vessel at a point distal to the occlusion, percutaneous balloon angioplasty is performed to restore blood flow through subintimal recanalization. This is a highly skilled technique with a low to moderate success level of consistent re-entry at the physician's preferred location just distal to the occlusion.
There are number of other related art catheters and methods for forming lateral penetrations through tissue to and from blood vessels past total occlusions, some of these are described in U.S. Pat. Nos. 5,443,497; 5,429,497; 5,409,019; 5,287,861; 6,231,546; 6,217,527; 6,506,178; 6,221,049; 6,235,000; 6,511,458; 6,719,725; 7,004,173; and 7,179,270, all of which are incorporated by reference for teaching reentry catheters, methods and for the purpose of written description and enablement requirements. These related art methods embody penetration of a needle exiting through either a side port or through a distal port, the needle must be oriented properly to ensure that the needle, when deployed, re-enters at a preferred location distal to the occlusion. One problem with these methods is a tendency of the catheter to back out as a result of the moment imposed by force required to penetrate the subintimal layers to gain access to the vessel true lumen. This is particularly problematic in the presence of calcified lesions causing an increase in the forces necessary for successful re-entry and, in many cases, requiring the physician to re-enter at a sub-optimal location.
SUMMARY
The invention is directed to a medical device and method thereof that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An advantage of the invention is the reduction in the forces required to cross the subintimal layer during device reentry into the true vessel lumen due to the articulating cannula or sharp member.
Yet another advantage of the invention is the reduction in the overall required size of the device since a long rigid element is not needed at the distal tip to support large reentry forces.
Still another advantage of the invention is improved stability and control of the distal tip during deployment of the cannula or interventional wire upon reentry from the subintimal space to the true vessel lumen thereby preventing against the device backing out or further separating the intima from the adventitia.
Yet another advantage of the invention is improved trackability and control, thereby allowing a physician or operator to re-enter the true vessel lumen at their preferred location close to the distal end of the total occlusion.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, is to provide a method for crossing an obstruction in a blood vessel. The method includes advancing a guide wire into an interstitial space of a vessel. Next, a catheter is advanced into the subintimal space with the aid of the guide wire. This may be accomplished using a traditional over the wire approach or using a rapid exchange catheter. For example, a rapid exchange reentry catheter method and catheter is described herein and also in U.S. Provisional Patent Application Ser. No. 61/503,477, and U.S. patent application Ser. No. 13/229,378, which are hereby incorporated by reference in their entirety and for all purposes.
In a preferred embodiment, the operator activates the reentry member through either a push or pull mechanism or the deployment of a balloon to direct the sharp from the subintimal space into the vessel lumen. Through this preferred embodiment, reentry into the true lumen of a vessel is accomplished at a location immediately distal to the total occlusion. It is noted that other locations may also be used for reentry. Preferably, the reentry member is configured to exit the lateral port and into the true lumen of the vessel from the subintimal space prior to advancement of an intervention wire through the lateral port.
Another aspect of the invention is directed towards a catheter system that includes a catheter having a proximal end, a distal end, lateral port, and at least one lumen. At least one lumen extends longitudinally through at least the lateral port of the catheter. The catheter includes a reentry member which is configured to gain access to a vessel true lumen from a subintimal space. The reentry member is configured to penetrate the vessel layers adjacent to the distal port. In a preferred embodiment, the reentry member has one or more sharpened edge surfaces along a distal portion of the cutting device. The reentry member is configured to have a hollow portion to receive an interventional guide wire.
Yet another aspect of the invention is directed towards a reentry catheter for use in forming a pathway in an interstitial space of an artery. The reentry catheter includes a catheter body including a proximal end, a distal end, at least one lumen, and at least one port. An exchange port is arranged on at least a distal portion of the catheter body and the exchange port includes at least one lumen configured to receive a guidewire and the catheter body is configured to track over the guidewire to a treatment site. A reentry member is slidably arranged within the lumen of the catheter body and is configured to deploy through the catheter body port. In one embodiment, the reentry member is configured to deploy from a first location within the interstitial space of an artery to a second location within a true lumen of the artery upon application of a substantially eccentric force to a distal portion of the reentry member.
Still yet another aspect of the invention is directed towards a reentry catheter for use in forming a pathway in an interstitial space of an artery. The reentry catheter includes a catheter body having a proximal end, a distal end, at least one lumen, and at least one port. An exchange port is arranged on at least distal portion of the catheter body. The exchange port is configured to receive a guidewire and the catheter body is configured to track over the guidewire to a treatment site. A reentry member having a proximal end, a distal end, at least one lumen is configured to be slidably positioned within the lumen of the catheter body. The reentry member includes a portion having a sharp surface to permit dissection of a portion of an artery. A tether is coupled to a distal end portion of the reentry member and the reentry member is configured to deploy through the at least one port from a first location within the interstitial space of an artery to a second location within a true lumen of the artery upon application of a force to the tether.
Another embodiment of the invention is directed towards a method of crossing an obstruction in a blood vessel with a reentry catheter in a subintimal space of a vessel. The method includes advancing a first guide wire into a lumen of the vessel towards the obstruction in the vessel. Advancing the first guide wire into the subintimal space of the vessel to a location distal of the obstruction and advancing a catheter comprising reentry member over the guide wire to a location where a port of the catheter is at a location distal of the obstruction. The reentry catheter may be advanced in an over the guidewire configuration through a lumen of the catheter body or via an exchange port through a lumen of the exchange port. The method further includes deploying a portion of a segmented reentry member through the port from a first location within the subintimal space of the vessel to a second location within a true lumen of the vessel upon application of a substantially eccentric force to a distal portion of the reentry member. Next, the method may include returning the reentry member from the second location to the first location and removing the reentry catheter from the vessel.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.



BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.
In the drawings:
FIG. 1 illustrates an exemplary side view of a reentry catheter according to an embodiment of the invention;
FIG. 2 illustrates an exemplary side view of the reentry member of the reentry catheter illustrated in FIG. 1;
FIG. 3 illustrates a cross-sectional view of the reentry member illustrated in FIG. 2 taken along A to A;
FIG. 4 illustrates a reentry member in a second configuration according to another embodiment of the invention;
FIG. 5 illustrates an exemplary side view of a reentry catheter according to another embodiment of the invention; and
FIG. 6A-6H illustrates an exemplary method for using a medical device of FIG. 1 and FIG. 5.



DETAILED DESCRIPTION
The invention generally relates to a method and system for crossing an obstruction in a tubular member, e.g., crossing a chronic total occlusions in a blood vessel, and more particularly to a medical device method for crossing of an occlusion in a subintimal or interstitial space of an artery. Subintimal or interstitial region or space is at a location beneath at least a portion of intima and preferably at a location contained between the intima and the adventitia of the vessel. The terms tubular member, artery, vessel and bodily passable are used interchangeably throughout the specification.
An embodiment of the invention is directed towards a catheter for insertion into a subintimal space. The catheter includes a proximal end, a distal end, at least one lateral port, and at least one lumen. The at least one lumen extends longitudinally through the lateral port of the catheter. The catheter may also include an exchange port, e.g., RX port, arranged along an exterior portion of the catheter body and configured to receive a second wire or guide wire. The exchange port may be broken into two or more segments along the length of the catheter.
The catheter also includes a reentry member including a plurality of segments. However, the reentry member may include only one segment configured to pivot or two or more segments. At least one of the segments is configured to operate out of a portion of the lateral port. In one embodiment, at least one of segments is configured with one or more sharp surfaces near its distal end. Alternatively, the cutting surface may extend along each of the plurality segments along the entire surface of the reentry member or only a predetermined portion the reentry member. Preferably, the cutting surface is configured to gain access from the subintimal or interstitial region or space to the true lumen of the vessel. In one embodiment, the reentry member includes a lumen for receiving a guide wire or supplemental treatment device.
Another embodiment is directed towards a reentry catheter for use in forming a pathway in an interstitial space of an artery. The reentry catheter includes a catheter body having a proximal end, a distal end, at least one lumen, and at least one port. A reentry member is arranged within the at least one lumen of the catheter body and include a proximal end, a distal end, a lumen, and a plurality of segments. The distal end of the reentry member is configured to deploy through the at least one port from a first location within the interstitial space of an artery to a second location within a true lumen of the artery upon application of an eccentric force to a distal portion of the reentry member. A tether, coil, linkage of other suitable mechanism is coupled to a distal end portion of the reentry member configured to provide the application of a substantially eccentric force.
The supplemental treatment device may include guide wires, medical instruments, balloons, stents, laser catheters, optical fibers, visualization devices, medications and other medical instruments known in the art. In a preferred embodiment, the lumen portion of the reentry member is configured to receive a guide wire having a diameter in a range from about 0.01 inches to about 0.04 inches or larger.
The plurality of segments includes at least a first segment having two pivot joints and a second segment coupled to one of the pivot joints. The pivot joints include bearing surfaces, e.g. bush bearings, pop rivets, pins, and the like, as known in the art. The pivot joint may also be spring loaded to provide aid in retracting or advancement of the reentry member.
In other embodiments, the plurality of segments may have a load or force built into the pivot joints. For example, the pivot joint may have spring within the joint. A shroud or other structure may be used to prevent movement. After the shroud or other structure is removed, at least a portion of the plurality of segments is released from a first position to second position.
Suitable materials for the plurality of segments include but are not limited to steel, alloys, nitinol, titanium, thermoplastics, including PEEK or polyimide, and combinations thereof and the like. The reentry member may also be configured to have a predetermined shape, i.e., resilient shape, straight shape, curved shaped, memory shape, and combinations thereof.
The catheter may be constructed from various materials as known in the art. For example, the catheter may be constructed from materials, such as polyesters; polyurethanes; polyamides; polyolefins including polyethylene and polypropylene; and any copolymers thereof. Some more specific examples of suitable materials include, but are not limited to: nylon; polyester elastomer; polyetherlblock polyamide, such as PEBAX, Hytrel, and/or Amitel; polyamid such as Grilamid; flouro-polymer, such as Kynar; polyether ether ketone (PEEK); polyethylene (PE); polyurethane; polyolefin copolymer (POC); tetrafluoroethylenes, such as polytetrafluoroethylene (PTFE).
Other suitable materials for the catheter include steel, including laser cut stainless steel. The catheter may comprise coils as described in FIG. 9C as described in paragraphs [0101] and [0102] of U.S. Publication No. 2010/0063534, which is hereby incorporated by reference as if fully set forth herein. The catheter may include at least one lumen that is configured to allow supplemental treatment devices access to the interior of the lumen.
Another embodiment of the invention is directed towards a method of crossing an obstruction in a blood vessel with a reentry catheter in a subintimal space of a vessel. The method includes advancing a first guide wire into a lumen of the vessel towards the obstruction in the vessel. Advancing the first guide wire into the subintimal space of the vessel to a location distal of the obstruction and advancing a catheter comprising reentry member over the guide wire to a location where a port of the catheter is at a location distal of the obstruction. The reentry catheter may be advanced in an over the guidewire configuration through a lumen of the catheter body or via an exchange port through a lumen of the exchange port. The method further includes deploying a portion of a segmented reentry member through the port from a first location within the subintimal space of the vessel to a second location within a true lumen of the vessel upon application of a substantially eccentric force to a distal portion of the reentry member.
Next, the method may include returning the reentry member from the second location to the first location and removing the reentry catheter from the vessel.
The deploying of the segmented member may be accomplished with by inflating an elastomeric member, applying an electrical current to the segmented member, removing a shroud on a preloaded force of a segmented member, or applying an force to a tether member located at distal portion of the reentry catheter.
The orientation and the location of the catheter and its lateral port with respect to the occlusion may be directed through the use of radiopaque markers and visualization techniques known in the art. Once the catheter has been properly oriented, the operator moves the reentry member from the stowed or locked position and subsequently articulates the member such that a precise incision is made between the subintimal space and the true vessel lumen. A second interventional guide wire, in the case of a rapid exchange catheter, or the first guide wire for an over the wire configuration is advanced into the vessel lumen through the hollow portion of the reentry member. Once the intervention wire is in place, the reentry member may be refracted and the entire reentry catheter removed. Of course, more than one wire may also be used in the over the wire technique.
Yet another embodiment of the invention is directed towards a kit. The kit includes a reentry catheter according to embodiments of the invention and optionally directions for use. The kit may also include a supplemental treatment device, e.g., a balloon, optical catheter, visualization catheter, stent, embolic protection device and the like. In addition, the kit may include valves and other devices that may be used in medical procedures.
Reference will now be made in detail to an embodiment of the present invention, example of which is illustrated in the accompanying drawings.
FIG. 1 illustrates an exemplary side view of a reentry catheter according to an embodiment of the invention.
Referring to FIG. 1, a reentry catheter according to this embodiment is generally depicted as reference number 100. The catheter 100 is configured to permit a user to cross an obstruction, e.g., partial or total occlusion, in a subintimal space of a vessel. The catheter 100 also enables fast and simple true lumen reentry without the need for active visualization, e.g., IVUS visualization. Visualization may be used to assist procedures of the invention, e.g., the visualization may be active or passive. In one embodiment, visualization features or systems are added as described with reference towards U.S. Patent Application Publication No. 2005/0171478, which is hereby incorporated by reference.
The catheter 100 is flexible and has a proximal end 102 and a distal end 104. The proximal end 102 is attached to a handle (not shown). A shaft 106 extends from the proximal end 102 of the catheter to the distal end of a rigid shroud or cover 108. The shaft 106 may be constructed of conventional techniques. In a preferred embodiment, the shaft includes braided, double braided, or by triplex construction as described in U.S. Patent Application No. 61/503,477, which is hereby incorporated by reference. A lateral port 110 is located near the distal end 104 and preferably in the rigid shroud 108. Alternatively, or in addition to, a lateral port (not shown) may also be located in the shaft 106. The shaft 106 includes at least one lumen 114 extending at least partially along the entire shaft 106 and exiting out the catheter distal end 104. In some embodiments, the lumen 114 may be used to provide supplemental treatment devices to the distal tip of the catheter 100.
The distal end of shaft 106 is connected to the proximal end of shroud 108 preferably by a laser weld, glue, over-molding or the like as known in the art. There may be more than one lateral port at a distal portion of the shroud 108.
Optionally, a flexible atraumatic tip 116 may be attached to the distal end of the shroud 108 preferably by a laser weld, glue, over-molding or the like as known in the art. Alternatively, the shroud 108 or cover (not shown) may extend to the catheter distal end 104 and be formed with an atraumatic tip profile. Further, an over molded distal extension (not shown) of the catheter may be incorporated to provide additional support during device orientation and during launch of the reentry member 112. The reentry member 112 is docked in a straight position, as shown in FIG. 1 while traversing through an artery and into or reversed out of the subintimal vessel space. Alternatively, a retractable shroud or cover (not shown) may be used to protect the vessel during catheter transport through the body.
At least one marker, e.g., a radiopaque marker, 118 is disposed on the body of the catheter near its distal end or integrated within the body of the catheter. The radiopaque marker 118 is used with standard visualization techniques, e.g. fluoroscopy, to guide the catheter through the body and into position in the subintimal space, to position the lateral port 110 and reentry member 112 at a desired location distal to the occlusion, and to determine whether the reentry member 12 is in the stowed, ready, or in a fully articulated position. Radiopaque markers as described in U.S. Patent Application No. 61/503,477, U.S. Patent Application 2010/0317973, U.S. Pat. No. 6,544,230, U.S. Pat. No. 6,719,725, or U.S. Pat. No. 6,231,546 may also be used, all of these patents and applications are hereby incorporated by reference as if fully set forth herein.
The reentry member 112 may be configured to permit other devices or supplemental devices to be operated through the lumen of the member 112. The supplemental devices may include a balloon, a cutting device, thrombectomy device, a guide wire, a filters, e.g., an embolic filter, optical devices, e.g., RF or laser ablation devices, combinations and the like. In addition, the reentry member 112 may be configured to have a predetermined shape, i.e., pre-resilient shape, straight shape, curved shaped, memory shape.
In a preferred embodiment, the lumen of the reentry member 112 is sized to accommodate a wide range of guide wire diameters such as guide wire diameters in a range from about 0.01 inches to about 0.04 inches or larger. Referring to FIG. 1, guide wire 120 is shown passing through a lumen of the reentry member 112 in its stowed position and passing through the distal end 104 of the catheter as would be the case when the catheter travels through the body and into or out of the subintimal space.
FIG. 2 illustrates an exemplary side view of the reentry member of the reentry catheter illustrated in FIG. 1. FIG. 3 illustrates a cross-sectional view of the reentry member illustrated in FIG. 2 taken along A to A. FIG. 4 illustrates a reentry member in a second configuration according to another embodiment of the invention.
Referring to FIGS. 2-3, the reentry member 112 includes a plurality of tear-dropped shaped segments 150 connected by pivot joints 152. The pivot joints 152 may include bearing surfaces including bush bearings, pop rivets, pins, and the like, as known in the art. In a preferred embodiment, each of the segments 150 would include a through lumen 154 for passage of a guide wire (not shown). The pointed edge of at least one distal segment would be sharpened to create a sharp edge 156 as depicted. A control wire 130 is coupled at a distal location with a weld 132 or other suitable coupling technology, e.g., adhesive, mechanical joint or fastener. In a preferred embodiment, the control wire 130 is coupled to a distal portion of the most distal segment. The segments 150 can be any length or number and also may contain any number of pivot joints 152. In addition, the pivot joint location may vary with each segment, e.g., the pivot joint location may be down a central axis of one of the segments and at a higher or lower location on an adjacent segment. Each segments may have different size, e.g., one segment may be longer, wider, or higher than another segment.
In one embodiment as shown in FIG. 4, an operator can control or operate the reentry member 112 by holding the catheter 100 in place and by pulling the control wire 130 at a proximal location. In this configuration, the control wire 130 is used to transmit force from the proximal end of the catheter 100 to distal portion of the reentry member. The location of the control wire 130 and the placement of the coupled end 132 are such that a moment is created causing the reentry member 112 to bend to a desired curvature.
In addition, the applied force is configured to provide the necessary force to articulate the device lumen 154 axis from an orientation about parallel to the vessel wall to an orientation between about 0 and about 180 degrees of the vessel wall and more preferably between about 5 and about 90 degrees with respect to the vessel wall.
Alternatively, a tether element may be used in place of a control wire to support articulation or bending of the distal segments of the reentry member 112 upon application of a proximal push force on the articulating device. Other configurations for the control wire 130 or tether (not shown) may include a pull cable or mechanical linkage, e.g., a Kevlar tendon.
Moreover, a mechanical advantage component (not shown) such as levers, manual gearing or electro-mechanical gearing may be incorporated at or near the proximal end of the catheter and more preferably in a handle such that the articulating cutting device or sharp member may be mechanically controlled through a simple one-handed operation.
FIG. 5 illustrates an exemplary side view of a reentry catheter according to another embodiment of the invention. Referring to FIG. 5, a reentry catheter according to this embodiment is generally depicted as reference number 200. An exchange port 222, e.g., rapid exchange port, is eccentrically located near the distal end of shaft 206. The exchange port 222 may include a jacketed polyimide tube trimmed flush to the profile of the device after processing to facilitate tracking and back loading of a first guide wire 220. The exchange port 222 may be sized to extend past a distal end of the catheter, be flush with the distal end of the catheter, or terminate a location proximal the distal end of the catheter.
Preferably, the guide wire 220 may have a diameter in a range from about 0.01 inches to about 0.04 inches or greater and be constructed of a range of materials as known in the art. In addition, the wire 220 may have lubricous coating, e.g., PVP thin film or PTFE, and/or a predetermined shape. Additionally, the wire 220 may be removed allowing supplemental treatment devices access to the distal tip of the catheter.
The catheter 200 is flexible and has a proximal end 202 and a distal end 204. The proximal end 202 is attached to a handle (not shown). A shaft 206 extends from the proximal end 202 of the catheter to the distal end of a rigid shroud 208. The shaft 206 may be constructed of conventional techniques, e.g. braided or double braided, or by triplex construction as described herein. A lateral port 210 is located near the distal end and preferably in the rigid shroud 208. Alternatively, or in addition to, a lateral port (not shown) may also be located in the shaft 206. The shaft 206 includes a lumen 214 extending at least partially along the entire shaft 206.
A reentry member 212 may be contained in the inner lumen of shaft 206 along substantially the length of catheter 200. In some embodiments, the reentry member 212 is hollow and allows for an optional second guide wire, cannula or other supplemental treatment device 224. The reentry member includes a plurality of interconnected segments. The distal end 204 of shaft 206 is connected to the proximal end of shroud 208 preferably by a laser weld, glue, overmolding or the like as known in the art. There may be more than one lateral port at a distal portion of the shroud 208. Optionally, a flexible atraumatic tip 216 may be attached to the distal end of the shroud 208 preferably by a laser weld, glue, over-molding or the like as known in the art. Alternatively, the shroud 208 may extend to the catheter distal end 204 be formed with an atraumatic tip profile.
Further, an over molded distal extension (not shown) of the catheter may be added to a distal end of the catheter 200 as described in U.S. Patent Application No. 61/503,477, which is hereby incorporated by reference as if fully set forth herein. The over molded distal extension is configured to provide additional support during device orientation and during launch of the reentry member 212. The reentry member 212 is docked in a straight position, while traversing through an artery and into or out of the subintimal vessel space. Alternatively, a retractable shroud cover (not shown) may be used to protect the vessel during catheter transport through the body.
The reentry member 212 may be mechanically controlled through the use of a tension member, a tether member or a balloon as described herein. Optionally, an additional lumen may be contained within the catheter 200 that may be used for supplemental treatment devices.
The catheter 200 optionally may include at least one radiopaque marker 218. In a preferred embodiment, the radiopaque markers are configured to ensure orientation of the lateral port towards the true lumen of the vessel. The radiopaque markers may also be configured to determine a spatial relationship of other attributes of the catheter, e.g., the spatial location of the distal end of the catheter, confirmation of the stowed position of the reentry member, etc. In a preferred embodiment, at least one marker 218 is arranged near a distal portion of the catheter. In addition, radiopaque markers may be added to at least one of the plurality of segments.
FIGS. 6A-6H illustrates an exemplary method for using a medical device of FIG. 1 and FIG. 5.
Referring to FIGS. 6A-6E, a guide wire 602 is advanced to an occlusion 606 in an attempt by the physician to cross the occlusion 606 to use conventional interventional devices such as laser atherectomy catheters, balloons, drug delivery devices, stents and the like. This advancement of the guide wire 602 is done in accordance with techniques known in the field of cardiology, interventional radiology and the like. In some instances, the physician is unable to cross through the lesion from the proximal lesion end to a point distal the lesion through the true lumen of the vessel. In these instances, as shown in FIG. 6A, the guide wire 602 may unintentionally or intentionally enter the subintimal space 604 after reaching the total occlusion 606. The guide wire 602 may include lubricious coating and have diameter in a range from about 0.01 inches to about 0.04 inches or larger. In addition, the guide wire 602 may be shapeable, deformable, or have other attributes designed for crossing an occlusion 606 directly or indirectly.
Referring to FIG. 6B, after the guide wire 602 has reached the subintimal space 604, a catheter 100 is advanced over the guide wire 602 into the subintimal space 604. Alternatively for the embodiment shown in FIG. 5, reentry catheter 200 could be used and advance through RX port 222 into the subintimal space 604. Of course, any catheter described herein may also be used and reference to catheter 100 and 200 is done merely out of convenience. Next, the catheter 100 is advanced to a position distal of the occlusion 606.
Referring to FIG. 6C, the catheter 100 is oriented to position such that the lateral port 110 is distal the occlusion 606. In a preferred embodiment, the orientation of the catheter 100 may be conducted with utilization of the radiopaque markers 118 as described previously and with reference to U.S. Patent Application No. 61/503,477, which is hereby incorporated by reference as if fully set forth herein. For example, in a preferred embodiment the catheter 100 is configured such that different views on fluoroscopic images enable the operator to align the lateral port 110 so that the reentry member 112 or other instrument, e.g., guide wire, working element, and the like, are aligned with a true lumen of the vessel. It is noted that other active or passive visualization techniques as known in the art may also be utilized to orient the lateral port 110 with a true lumen. Other visualization techniques may also be used to aid in orientation including incorporation of an active visualization element, such as an ultrasonic transducer or optical sensing element at a location either within the at least one catheter lumen, on or within the catheter body, or on or near the lateral port.
Once the catheter 100 is in position at a location distal to the occlusion 606 and the lateral port 110 and the reentry member 112 are oriented to articulate and launch into the true vessel lumen, the operator retracts the guide wire 602 to a position within the reentry member, as shown in FIG. 6D. The operator would then transition the reentry member 112 from a stowed, safe position, to a ready position in preparation for activation of the mechanical control for articulation. Alternatively this could involve retraction of a guard on the rigid shroud (not shown). Referring to FIG. 6E, reentry into the true vessel lumen is accomplished by the operator holding the catheter in place and articulating the reentry member 112 by application of a load as described in FIGS. 2-4 or through inflation of an internal balloon (not shown). In the alternative or in addition to, the activation mechanism may be linked to a simple handle such that the operator either rotates a knob or activates a mechanical or electro-mechanical control element to transition from a ready to an articulated or flexed configuration. The intervention guide wire 602 or another appropriate device may be passed through the shaft lumen 114 and the lumen 128 of the reentry member 112 into the true vessel lumen.
Alternatively for a rapid exchange configuration as described in FIG. 5 and FIG. 6F, retraction of guide wire 602 is not required. As with the previous embodiment, the operator would transition the reentry member 212 from a stowed, safe position, to a ready position in preparation for activation of the mechanical control for articulation. Alternatively this could involve retraction of a guard on the rigid shroud (not shown). Reentry into the true vessel lumen is accomplished by the operator holding the catheter 200 in place and the reentry member 212 by techniques as described with regard to FIGS. 2-4, a push mechanism could also be employed or through inflation of an internal balloon could be utilized for deployment of the reentry member 112.
The reentry member 112 may be linked to a simple handle (not shown) such that the operator either rotates a knob or activates a mechanical or electro-mechanical control element to transition from a ready to an articulated of flexed configuration. The guide wire 602 or another appropriate device may be passed through the shaft lumen 214 and the lumen of the reentry member 212 and into the true vessel lumen. The intervention guide wire may be sized from about 0.10 inches to about 0.40 inches or larger and may contain a lubricous coating as known in the art.
The reentry member 112 reenters the vessel lumen at an angle in a range from about 5 degrees to about 180 degrees, more preferably at an angle in range from about between about 5 degrees to about 90 degrees. The sharp edge 156 on the reentry member 112 dissects the vessel wall from the subintimal space 604 into the true vessel lumen. It is thought that the cutting action significantly reduces the force required to safely and accurately reenter the vessel lumen even in the presence of calcified tissue. This reentry force is suspected to be significantly lower than the forces required for known reentry devices, which require lateral extension of the catheter. Moreover, the reentry device 112 includes an improved torsional control to support reentry forces. During reentry, the vessel wall tends to pull away from a more traditional reentry cannula tip during reentry such that penetration will require an increased force application and possible multiple attempts to successfully enter the lumen. The use of a reentry member overcomes this challenge posed by the prior art and allows the operator to reenter at their preferred location easily and repeatedly. Moreover, it is thought that the use of the reentry member results in more consistent reentry at a location closer to the distal point of the occlusion 606 as compared to the use of a simple curved cannula as known in the art.
Referring to FIGS. 6E-6H, after the proper reentry of the reentry member 112 has been confirmed to be directed towards the true lumen of the vessel, another instrument, e.g., guide wire, working element, and the like, exits the lateral port 110 and reenters the vessel. Once the intervention guide wire or intervention device is in position, the reentry member is retracted back into the lateral port 110 of the catheter 100 and the catheter is removed as shown in FIG. 6H. Optionally, both the catheter 100 and guide wire 602 may be left in place. Now that the total occlusion 606 is crossed various interventional procedures as known in the art may be performed. For example, a balloon catheter (not shown) may be used to dilate the subintimal space along with possible stent placement (not shown) to provide an alternative lumen through the subintimal space 604 and back into the true vessel to restore adequate blood flow post-procedure.
It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

## Claims

1. A method of crossing an obstruction in a blood vessel, the method comprising the steps of:
advancing a first guide wire into a lumen of the vessel towards the obstruction in the blood vessel;
advancing the first guide wire into a subintimal space of the vessel to a location distal of the obstruction;
advancing a catheter comprising a reentry member over the guide wire to a location where a lateral port of the catheter is at a location distal of the obstruction, wherein the reentry member comprises a plurality of segments, wherein at least two of the plurality of segments comprise a tear drop shape, and wherein at least one of the tear drop shaped segments comprises a sharp edge; and
deploying the tear drop shaped segments through the lateral port from a first location within the subintimal space of the vessel to a second location with the lumen of the vessel that is distal of the obstruction and upon application of a substantially eccentric force to a distal portion of the reentry member.

2. The method of claim 1, further comprising the steps of:
returning the reentry member from the second location to the first location; and
removing the reentry member from the vessel.

3. The method of claim 1, wherein the deploying step comprises a step of inflating an elastomeric member.

4. The method of claim 1, wherein the deploying step comprises applying an electrical current to the reentry member.

5. The method of claim 1, wherein the deploying step comprises applying a force to a tether member located at a distal portion of the reentry member.

6. The method of claim 1, wherein the sharp edge of the at least one of the tear drop shaped segments allows the reentry member to the gain access from the subintimal space to the lumen of the vessel.

7. The method of claim 6, wherein the sharp edge of the at least one of the tear drop shaped segments dissects a portion of a wall of the vessel from the subintimal space into the lumen of the vessel.

8. The method of claim 1, wherein the eccentric force is applied with at least one of a control wire, a cabling device, a ramp, and an elastomeric member.

9. The method of claim 8, wherein the control wire is coupled to the reentry member with at least one of an adhesive, a weld, and a mechanical joint.

10. The method of claim 9, wherein the control wire comprises a plurality of wound wires.

11. The method of claim 1, wherein at least one of the plurality of segments rotates about a point.

12. The method of claim 1, wherein at least one of the plurality of segments comprises two pivot joints.

13. The method of claim 1, wherein the reentry member comprises a longitudinal axis and wherein the tear drop shaped segments comprise a lumen extending therethrough along the longitudinal axis.

14. The method of claim 1, further comprising a step of removing the first guide wire from the reentry member and from the vessel.

15. The method of claim 14, further comprising a step of inserting a supplemental treatment device through the reentry member and into the lumen of the vessel.

16. The method of claim 15, wherein the supplemental treatment device comprises at least one of a second guide wire, a medical instrument, a balloon, a stent, a laser catheter, a medication, an optical catheter and combinations thereof.