Patent ID: 12226114

DETAILED DESCRIPTION OF THE INVENTIONS

In accordance with current terminology pertaining to medical devices, the proximal direction, or end, is defined herein as that direction, or end, on the device that is furthest from the patient and closest to the user, while the distal direction, or end, is that direction, or end, closest to the patient and furthest from the user. These directions and locations are applied along the longitudinal axis of the device, which is generally an axially elongate structure optionally having one or more lumens or channels extending through the proximal end to the distal end and running at least a portion of the length of the device. A catheter size given in the units of “French” or “Fr” is defined as three times the diameter in millimeters. Thus, a device that is 2 mm in diameter can be said to have a diameter of 6 French. Diameters can also be expressed in imperial units of inches.

In an embodiment, the inventions is an endoluminally, transvascularly, or endovascularly placed steerable microcatheter, with internal deflectability or the ability to articulate, at its distal end, in a direction away from its longitudinal axis. The steerable microcatheter is generally fabricated from stainless steel, nitinol, titanium, or the like and comprises an outer tube, an inner tube, a hub, and a distal articulating region. The deflecting or articulating mechanism is integral to the steerable microcatheter and component connections can rely on integral construction (1-piece), welds, bonds, connectors, or the like. The steerable microcatheter is useful for animals, including mammals and human patients and can be routed through body lumens or other body structures to reach its target destination. The steerable microcatheter can further comprise external polymeric sleeves, internal polymeric liners, exterior and interior coatings, and the like.

In an embodiment, the steerable microcatheter comprises at least an inner tube and an outer tube. The steerable microcatheter can also comprise a stylet or obturator, which can be removable or non-removable. The steerable microcatheter further comprises a hub at its proximal end which permits grasping of the steerable microcatheter as well as features, or control mechanisms, for controlling the articulation at the distal end. Such features can comprise control knobs, handles, levers, or the like. The proximal end further can optionally be terminated with one or more bayonet mounts or connectors, preferably female Luer or Luer lock ports or hemostasis valves, which can be suitable for attachment of pressure monitoring lines, dye injection lines, vacuum lines, a combination thereof, or the like. The steerable microcatheter can comprise a center lumen, channel, or channels, operably affixed to the Luer or Luer lock port, said channel being useful for dye injection, material or fluid administration or removal, pressure monitoring, implant delivery, or the like. In some embodiments, it is beneficial that another catheter be advanceable over the microcatheter beginning at the proximal end of the microcatheter.

The steerable microcatheter, or catheter, is fabricated so that it is, initially, substantially straight from its proximal end to its distal end. Manipulation of a control mechanism at the proximal end of the steerable microcatheter causes a distal region of the steerable microcatheter to bend or curve in a radial direction away from its longitudinal axis. The bending, steering, deflecting, or articulating region is located near the distal end of the steerable microcatheter and can be a flexible region or structure placed under tension or compression through control rods or tubular structures routed from the control handle at the proximal end of the steerable microcatheter to a point distal to the flexible region. The bending can be configured to occur in more than one region of the steerable catheter.

Other embodiments of the inventions comprise methods of use. One method of use involves inserting the central core wire or stylet so that it protrudes out the distal end of the steerable microcatheter. A percutaneous or cutdown procedure is performed to gain access to structures such as, but not limited to, the vasculature, either a vein, an artery, a body lumen or duct, a hollow organ, musculature, fascia, cutaneous tissue, the abdominal cavity, the thoracic cavity, and the like. A percutaneous access can involve placing an introducer, which can be a hollow, large diameter, hypodermic needle within the vasculature through a skin puncture. A guidewire (or the microcatheter itself, without the guidewire) can next be routed into the patient through the introducer. The introducer can be removed leaving the guidewire in place. The steerable microcatheter can be next inserted over the guidewire and into the patient. At this point, the guidewire can be removed, if desired. The microcatheter can be routed proximate to the target treatment site with the aid of its own internal steering mechanism to negotiate bifurcations, branch-vessels, and the like.

In an exemplary embodiment, a steerable microcatheter can be routed to a lesion in the cerebrovasculature by way of an entry point in a femoral artery. The steerable microcatheter can be routed cranially through the aorta and into a carotid artery. The steerable microcatheter can be routed through the carotid siphon, which is very tortuous, and on into the circle of Willis and adjacent vascular structures. Transit through the carotid siphon can be aided by prior placement of a floppy guide catheter, a guidewire, or both. Once routed to the target region in the cerebrovasculature, the distal tip can be articulated laterally. The degree of articulation and radius of curvature can vary. In an exemplary embodiment, the articulation occurs over a radius of about 3 to 4 mm and the degree of articulation approaches approximately 80 to 120 degrees. At this point, the distal end of the steerable microcatheter can reside within a cerebrovascular aneurysm that needs to be treated. An embolic coil can be deployed, for example using a pusher wire, from the distal end lumen of the microcatheter into the aneurysm. The embolic coil can be released from its pusher and left behind to form an implant to close off the aneurysm, either alone or in concert with additional coils or implants. A microcatheter with an internal lumen diameter of about 0.017 inches can be used to perform this type of procedure.

The steerable microcatheter can be adjusted so that it assumes a substantially straight configuration at any time. In other procedural embodiments, the steerable microcatheter can be advanced through the central lumen of an already placed catheter, sheath, introducer, or guide catheter. In other embodiments, the steerable microcatheter can be placed over an already placed guidewire, either standard or steerable. The steerable microcatheter comprises a generally atraumatic, non-sharp, distal tip. The distal tip can be rounded, oval, flattened, or the like. A central stylet wire, preferably removable, can be used to further blunt the distal end of the microcatheter.

In some embodiments, the steerable microcatheter is routed through the central lumen of an already placed guide catheter. The guide catheter can, in some embodiments, comprise extremely flexible structures that can conform to vascular anatomies that are quite tortuous. Such structures include the carotid siphon, located in the neck of a patient. The carotid siphon can comprise bends with radii of about 3-4 mm and the angle of articulation can reach to between 90 degrees and 180 degrees. This vessel can comprise a corkscrew shaped anatomy configured to allow the head to rotate from side to side and up and down. This vessel is the gateway to the circle of Willis and needs to be traversed to reach the majority of cerebrovascular vascular targets. The flexible guide catheter can be used to generate a liner within the carotid siphon thus allowing other devices, such as the steerable microcatheter to traverse the carotid siphon without potentially causing any damage to the vessel walls. Very flexible guide catheters, sometimes termed flow-directed catheters, can be advanced through the carotid siphon to provide this protection. Once the flow-directed guide catheter is placed, the steerable microcatheter can then be advanced therethrough and on into the distal cerebrovasculature.

In other embodiments, the steerable microcatheter can be configured to create a fenestration in a vessel wall. The steerable microcatheter can be configured to create a fenestration in a vessel wall, traverse soft tissue, and fenestrate and enter a second vessel. The steerable microcatheter can comprise a sharp tip, RF electrode, central cutting trocar, or the like. The steerable microcatheter can further be configured to deploy a shunt, stent, stent-graft, or the like which traverses between one vessel and another. The steerable microcatheter can comprise a balloon dilator at or near its distal end or at intermediate points. The steerable microcatheter can comprise a balloon expandable deployment mechanism for stents, stent grafts, shunts, and the like. In an exemplary embodiment, the steerable microcatheter can be configured to create the passageway and deploy an arteriovenous (AV) shunt, for example in the arm, the leg, or elsewhere in the body. Examples of AV shunts can include, but are not limited to, hepatic shunts for TIPS procedures, shunts in the legs to relieve hypertension, syncope, and the like, forearm shunts, injection shunts for drug delivery or dialysis, and the like.

The distal end of the steerable microcatheter, and optionally the body of the microcatheter as well, is sufficiently radiopaque that it is observable clearly under fluoroscopy or X-ray imaging. The steerable microcatheter, especially near its distal end, can be configured with symmetrical (for example rings or short hollow cylinders) or asymmetric radiopaque markers that provide some indication regarding the side of the steerable microcatheter that deflection can occur. The location of the steerable microcatheter and the amount of deflection and curvature of the distal end are observed and controlled using fluoroscopy or X-ray imaging, or other imaging method such as MRI, PET scan, ultrasound imaging, and the like. One or more radiopaque markers can be affixed to the distal end of the steerable microcatheter to enhance visibility under fluoroscopy. Such radiopaque markers can comprise materials such as, but not limited to, thick ferrous metals, tantalum, gold, platinum, tungsten, platinum iridium, and the like. Polymeric components of the steerable microcatheter can further be loaded with barium compounds, bismuth compounds, and the like.

Deflection of the distal tip to varying degrees of curvature, under control from the proximal end of the microcatheter can be performed. The curve can be oriented along the direction of a branching vessel or vessel curve so that the steerable microcatheter can then be advanced into the vessel by way of its high column strength and torquability. Alignment with any curvature of the catheter can be completed at this time. When correctly positioned under fluoroscopy, ultrasound, or other imaging system, dye can be injected into the central lumen of the steerable microcatheter at its proximal end and be expelled out of the distal end of the steerable microcatheter to provide for road-mapping, etc. This steering function can be very beneficial in device placement and is also especially useful in highly tortuous vessels or body lumens which may further include branching structures such as bifurcations, trifurcations, and the like.

In some embodiments, the inner tube, the outer tube, or both, can have slots imparted into their walls to impart controlled degrees of flexibility. The slots can be configured as “snake cuts” to form a series of ribs with one or more spines. The spines can be oriented at a given circumferential position on the outer tube, the inner tube, or both. The spines can also have non-constant orientations. In some embodiments, only the outer tube is slotted. In preferred embodiments, the backbone segments (or double backbone segments) can be configured to substantially restrict or prevent tube length compression or expansion (or both), but allow the inner tube to transmit longitudinal forces to the distal steering region without loss of flexibility in certain regions. The double backbone segments can be configured so as to symmetrically transmit forces longitudinally through the microcatheter. The slots can be generated within the distal portion of the outer tube where the curve is generated and these slots can be selectively oriented to provide a preferential bend direction. The slots and/or coils can also be generated within the distal portion of the outer tube where the curve is generated and these slots can be variable in nature to selectively have variable oriented flexibility in the preferential direction. This distance can range between about 0.5-cm and 15-cm of the end and preferably between 0.5-cm and 5-cm of the distal end. The slot widths can range between 0.0005 inches and 0.100 inches with a preferable width of 0.001 to 0.003 inches. In exemplary embodiments, the slot widths are about 0.0015 to 0.0060 inches. In some embodiments, it is desirable to have the outer tube bend in one direction only but not in the opposite direction and not in either lateral direction. In this embodiment, cuts can be made on one side of the outer tubing within, for example, the distal 10-cm of the tube length. Approximately 5 to 30 cuts can be generated with a width of approximately 0.0010 to 0.0060 inches. The cut depth, across the tube diameter from one side, can range between 10% and 90% of the tube diameter. In an embodiment, the cut depth can be approximately 40% to 60% of the tube diameter with a cut width of 0.025 inches. An intermediate cut can be generated on the opposite side of the tube. In an embodiment, the outer tube can be bent into an arc first and then have the slots generated such that when the tube is bent back toward the intermediate cuts, the tube will have an approximately straight configuration even through each tube segment between the cuts is slightly arced or curved. The number of these fenestrations in the tube wall can vary depending on required bendability. In some embodiments, the slots can be spaced between about 0.005 inches to about 0.025 inches or more. In more preferred embodiments, the slots can be spaced about 0.008 to 0.020 inches. In preferred embodiments, the slots are configured to allow the steerable microcatheter to traverse radii as small as 3 mm.

FIG.1Aillustrates a side view of a steerable microcatheter100comprising a distal outer tube102, an inner control tube or rod104, an outer low-friction coating106, an exterior seal layer118, an intermediate outer tube108, a proximal outer tube110, a hub body112further comprising a hub body lumen124, a jackscrew traveler114, a stopcock or hemostasis valve126, an internal O-ring or seal (not shown), a fluid-tight connector128, one or more interior lumens130, and a control knob116.

Referring toFIG.1A, the distal end of the inner control tube or rod, hereafter called the inner tube,104is affixed to the distal end of the distal outer tube102using a weld, solder joint, adhesive bond, fastener, fixation device, or the like. The inner control tube or rod104is slidably disposed within the inner lumen of the distal outer tube102except at the distal end where they are affixed to each other. The proximal end of the distal outer tube102is affixed to the distal end of the intermediate outer tube108by integral formation, a weld, fixation device, adhesive bond, or the like. The proximal end of the intermediate outer tube108is affixed to the distal end of the proximal outer tube110by integral formation, a weld, fixation device, adhesive bond, or the like. The exterior of the outer tube can be covered with a fluid-tight seal118, which can prevent fluid egress or ingress through the plurality of slots cut into the tubes. The fluid tight seal layer118can comprise materials such as, but not limited to, PET, PTFE, PFA, polyimide, polyurethane, and the like. The wall thickness of the fluid tight seal layer118can be about 0.0001 to about 0.0010 inches or more, with a preferred thickness of about 0.0002 to 0.0005 inches. The fluid-tight seal layer can, in preferred embodiments, comprise elastomeric materials that can stretch and compress in concert with the slots in the tubes opening and closing. Furthermore, the fluid-tight seal layer beneficially does not substantially droop or curve inside the slots, a situation that could restrict follow-on bending properties of the steerable microcatheter. The entire outer tube assembly102,108,110,118, can be covered with an optional anti-friction coating or layer106. The coating106can comprise materials such as, but not limited to, a hydrophilic material such as hydrogel, silicone oil, or the like.

The microcatheter comprises one or more through lumens130to permit infusion of fluids therethrough or for advancement of a stylet (not shown) beyond the distal end of the microcatheter100. The control knob116is rotationally free to move within the hub body112, to which it is longitudinally affixed and the two components do not move axially relative to each other. The jackscrew traveler114can move axially within a lumen124within the hub body112within the constraints of the end of the internal lumen124of the hub body112. The jackscrew traveler114is keyed within the lumen124by a non-round cross-section that impinges on complimentary structures within the hub lumen124to prevent relative rotational movement of the two components112,124. The jackscrew traveler114comprises external threads that are complimentary and fit within internal threads of the control knob116. Thus, when the control knob116is turned, the jackscrew traveler114is forced to move axially either forward or backward because the control knob116is longitudinally affixed within the hub body112.

A thread pitch for the jackscrew traveler114and the control knob116can range from about 5 to about 64 threads per inch (TPI) with a preferred range of about 10 TPI to about 48 TPI and a more preferred range of about 15 to about 36 TPI.

FIG.1Billustrates a magnified, side cross-sectional view of the steerable microcatheter100ofFIG.1Aat the transition between the distal end of the intermediate region108and the proximal end of the distal, steerable region. The steerable microcatheter100transition region comprises the intermediate outer tube108, the distal outer tube102, the inner tube104, the central lumen130, the fluid barrier118, and the polymeric outer coating106. In other embodiments, the fluid barrier118can comprise an inner tube or coating disposed on the interior of the innermost tube which then lines the lumen or lumens130.

The polymeric outer coating106is optional but beneficial and can comprise materials such as, but not limited to, fluoropolymers such as PTFE, PFA, FEP, polyester (PET or PETG, polyamide, PEEK, and the like. The polymeric outer coating106can render the coiled embodiment of the intermediate outer tube108, as illustrated, to retain a relatively smooth exterior surface and provide for friction reduction which is useful when passing a long, slender microcatheter through a long, catheter lumen. The distal outer tube102can be affixed to the intermediate outer tube108by means of a weld, fastener, adhesive bond, embedment with polymeric, metallic, or ceramic materials, or the like. The intermediate outer tube108, illustrated in this embodiment as a coil structure with substantially no spacing between the coils, is highly flexible and the flexibility can be controlled by the elastic modulus, thickness, and other material properties of the outer coating106. The intermediate outer tube108, in other embodiments, can comprise structures such as, but not limited to, an unperforated or unfenestrated tube, a tube with partial lateral cuts, T-slots, H-slots, a spiral cut tube, a ribcage with a backbone, or the like.

FIG.2Aillustrates a side view, in partial breakaway, of the distal end of the axially elongate distal outer tube102, comprising a lumen214, a proximal, uncut portion212, a plurality of lateral partial cuts216, formed into longitudinal “T” or “H” cuts.

Referring toFIG.2A, the distal outer tube102serves as the outer tube of the steerable microcatheter such as that illustrated inFIG.1. The plurality of partial lateral cuts216serve to render the region of the outer tube102in which the lateral cuts216are located more flexible than the proximal region212. The plurality of longitudinal “T” cuts (looking from a side), serve to further render the region of the outer tube102, in which the “T” cuts reside, more flexible than in tubes where such “T” cuts216were not present. The longitudinal “T” cuts are optional but are beneficial in increasing the flexibility of the outer tube102in the selected bend region. The “T” cuts can also be described as “H” slots or just be laterally disposed slots or partial lateral slots. The longitudinal region comprising the slots216serve to distribute bending stress and reduce the possibility of structural yield during bending.

The partial lateral slots216can be spaced apart by about 0.005 to about 1.0 inches with a preferred range of about 0.008 inches to about 0.5 inches and a further preferred range of about 0.01 inches to about 0.025 inches. In an exemplary embodiment, the partial lateral slots216are spaced about 0.01 inches apart. The spacing between the partial lateral slots216can vary. In some embodiments, for example, the spacing between the partial lateral slots toward the proximal end of the outer tube102can be about 0.300 inches while those partial lateral slots216nearer the distal end of the outer tube102can be spaced about 0.150 inches apart. The spacing can change in a step function, it can change gradually moving from one end of the outer tube102to the other, or it can increase and decrease one or more times to generate certain specific flexibility characteristics. Increased spacing increases the minimum radius of curvature achievable by compression of the partial lateral slots216while decreased spacing allows for a smaller minimum radius of curvature.

The number of lateral cuts216can number between about four and about 5,000 with a preferred number being between about six and about 300 and a more preferred number of about eight to about 50. In the illustrated embodiment, there are 12 partial lateral cuts216, all of which are modified using “T”-slot (they could be referred to as “H” slots depending on how you look at them) configurations. In other embodiments, the partial lateral cuts216can be shaped differently. For example, the partial lateral cuts216can be at angles other than 90 degrees to the longitudinal axis, curved, V-shaped, Z-shaped, W-shaped or the like. In other embodiments, the “T” slots218can have, for example, further cuts approximately lateral to the longitudinal axis, along any portion of the “T” cut.

The outer tube102can have an outer diameter of about 0.005 to about 0.250 inches with a preferred outside diameter of about 0.010 to about 0.100 inches and a more preferred diameter of about 0.015 inches to about 0.080 inches. In the illustrated embodiment, the outside diameter is about 0.048 inches while the inner diameter is about 0.036 inches. The inside diameter of the outer tube102can range from about 0.002 inches to about 0.240 inches for the diameters cited herein.

FIG.2Billustrates an embodiment of a side view, in partial breakaway, of the distal end of an axially elongate inner tube104, comprising a lumen224, a proximal, uncut portion222, a longitudinal slot226further comprising an angled lead in228, a free side234, a pusher or connected side232, and a distal tip230.

Referring toFIG.2B, the distal tip230interconnects the free side234and the pusher side232. The distal tip230or end of the inner tube104can further comprise a rounded, tapered, or blunted tip or nose cone (not shown). The disconnected free side234and the connected pusher side232are generally integrally formed but can also be affixed to each other by welding, adhesives, solder joints, fasteners, or the like.

The lead in228to the longitudinal slot226is beneficially angled to prevent other microcatheters, stylets, or other devices, which are inserted through the central lumen224from being caught or bumping against an edge. The angled lead in228serves a guide to assist with traverse of a stylet, obturator, or microcatheter past the lead in228and into the distal region of the steerable microcatheter. The lead in228can be angled from between about −80 degrees (the angle can be retrograde) from the longitudinal axis (fully lateral) to about +2 degrees and preferably from about +5 degrees to about +20 degrees with a most preferred angle of about +8 degrees and about +15 degrees. In the illustrated embodiment, the angle of the lead in slot228is about 10 degrees from the longitudinal axis. A second feature of the lead in228is that it be positioned or located proximally to the most proximal “T” slot218in the outer tube102when the two tubes102,104are affixed to each other (seeFIG.9). The lead in228is located at least 1-cm proximal to the proximal most “T” slot218and preferably at least 2-cm proximal to the proximal most “T” slot218so that bending in the distal region does not distort the lead in228and cause kinking, misalignment, or pinching of the internal lumen224.

The inner or intermediate tube104can have an outside diameter that is slightly smaller than the inside diameter of the outer tube102so that the intermediate tube104can be constrained to move longitudinally or axially within the outer tube102in a smooth fashion with relatively little force exerted. In the illustrated embodiment, the outside diameter of the intermediate tube104is about 0.033 inches giving about a 0.0015 inch radial clearance between the two tubes102and104. The inside diameter of the intermediate tube104can range from about 0.006 to about 0.015 inches less than the outside diameter of the intermediate tube104. In the illustrated embodiment, the wall thickness of the intermediate tube is about 0.006 inches so the inside diameter of the intermediate tube is about 0.021 inches. The lumen224of the intermediate tube104can be sized to slidably accept a removable or non-removable stylet or obturator140(not shown). A typical stylet wire140can range in diameter from about 0.01 to about 0.23 inches with a preferred diameter range of about 0.012 to about 0.020 inches. In another embodiment, the outer tube102has an outside diameter of about 0.050 inches and an inside diameter of about 0.038 inches. In this embodiment, the inner tube104has an outside diameter of about 0.036 inches and an inside diameter of about 0.023 inches. The radial wall clearance between the inner tube102and the outer tube104is about 0.001 inches and the diametric clearance is about 0.002 inches. The annulus between the two tubes must be substantially smooth, free from burrs, and free from contamination because the two tubes102,104beneficially need to translate along their longitudinal axis relative to each other over relatively long axial distances of about 50 to about 150-cm.

The inner tube104transmits force along its proximal, stiffer, non-slotted region222from the proximal end of the inner tube104to the lead in228where the force continues to be propagated along the connected side232to the distal end230. The outer tube102transmits force along its proximal non-slotted region212. Longitudinal forces applied to the distal, flexible region with the slots216cause deformation of the outer tube in an asymmetrical fashion with the side of the outer tube102comprising the partial lateral slots216forming an outer curve if the slots216are expanded and an inside curve if the slots216are compressed. Forces to cause bending are preferably exerted such that the partial lateral slots216are compressed up to the point where the gap closes, but no further, however forces can also be exerted to expand the slots216, however limits on curvature are not in place because the lateral slots216can open in an unrestrained fashion except for the material properties of the outer tube102.

The disconnected side234of the inner tube104, separated from the connected side232by the longitudinal slot226and the lead in228, serves to maintain an undistorted tube geometry and provide resistance to deformation while helping to maintain the inner lumen224in a round configuration and provide a shoehorn or funnel effect to guide an obturator, microcatheter, or stylet140therethrough as they are advanced distally. The disconnected side234, being separated from the force transmitting member222cannot provide any substantial longitudinal load bearing structure, although at its distal end, where it is integral or affixed to the distal end230, some tension load carrying capability exists. The intermediate tube104can be considered a split tube and does not carry a load in compression or tension along substantially the entire length of the disconnected side234. A main advantage of keeping the disconnected side234is to maintain the off-center positioning of the force transmitting member222.

The partial lateral slot (or “T” slot)216in the outer tube102in the outer tube102, as well as the longitudinal slot226in the inner or intermediate tube104, and the lead in slot228can be fabricated by methods such as, but not limited to, electron discharge machining (EDM), wire EDM, photo chemical etching, etching, laser cutting, conventional milling, or the like. In other embodiments, different slot configurations can also be employed, such as curved slots, complex slots, zig-zag slots, or the like. In some embodiments, the partial lateral slot216can be configured with a tongue and groove or dovetail design to prevent or minimize lateral movement or torqueing of the outer tube102in the flexible region. In some embodiments, the tongue and groove or dovetail (not shown) can be generally centered between two “T” slots, for example. The parts can be ganged and fixture such that, using wire EDM, for example, a plurality of tubes can be cut to reduce manufacturing costs. As many as 20 to 30 tubes, or more, can be fixtured, secured, and etched by the aforementioned methods.

FIG.3illustrates a side, cross-sectional view of an embodiment of a hub end300of a steerable microcatheter. The hub end300comprises the outer proximal tube110, the intermediate tube104, a hub body302further comprising an integral stopcock body, a stopcock petcock304further comprising a petcock handle308and a petcock through bore306, a Luer lock fitting312, a keyed lumen334, a setscrew or pin320, a jackscrew body316further comprising a plurality of threads328and a central lumen332, a control knob314further comprising a plurality of threads318, a central lumen330, the protrusion338, and a circumferential recess322, an outer tube weld324, an orientation mark340, and an intermediate tube weld326. The hub body302can further comprise a plurality of recesses or complementary structures336. The hub300can also comprise an arrow pointer310to assist in orientation of the direction of curvature at the distal end of the steerable microcatheter by reference points on the hub300. In other embodiments, the hub can comprise gauges, audio output systems, visual output systems, or other mechanisms (not shown) to provide feedback as to the amount of articulation being imposed on the distal end of the microcatheter.

Referring toFIG.3, the petcock304is affixed to the petcock handle308by welding, integral fabrication, fasteners, adhesives, or the like. The petcock304is retained within a lateral through bore in the hub body302, which is in the illustrated embodiment, tapered, using a locking “C” washer, fastener, screw, pin, or the like (not shown). The stopcock body (not shown) can also be separate from the hub body302and be affixed thereto by welding, bonding, fasteners, and the like. The petcock304can be rotated about its longitudinal axis to align the through bore306with the axis and central lumen of the hub body302or it can be rotated sideways to shut off and seal the lumen against the flow of fluids. The Luer lock312can be affixed to, or integrally fabricated with, the hub body302. The knob314is retained within the hub body302by the setscrew of pin320which prevents axial movement but permits rotational movement as constrained by the setscrew, projection, or pin320riding within the circumferential recess322which is integrally formed or affixed to the knob314. The jackscrew body316is capable of axial movement within the hub body302but is restrained from rotation about the long axis by flats or features on the exterior of the jackscrew body316which are constrained by flats or features in the keyed lumen334. The knob314comprises threads328on its internal lumen which engage with external threads318on the jackscrew body316. Rotation of the knob314thus causes the jackscrew body316to move axially proximally or distally with mechanical advantage. Rotation of the knob314can be forced using manual action or using a motor or other mechanism (not shown). The proximal outer tube110can be affixed to the jackscrew body316by the outer tube weld324. The inner tube104(which can also be called the intermediate tube) is affixed to the hub body302by the intermediate tube weld326. The central lumen224of the inner tube104is operably connected to a central lumen of the hub body302, the petcock through bore306, and the lumen of the Luer fitting312.

The knob314can comprise markings340to permit the user to visualize its rotary or circumferential position with respect to the hub body302. These markings340can comprise structures such as, but not limited to, printed alphanumeric characters (not shown), a plurality of geometric shapes such as dots, squares, arrows, or the like, or the markings can comprise raised or depressed (embossed) characters of similar configuration as described for the printed markings. In an embodiment, the knob314can comprise a number on each of the facets so the facets can be numbered from one to 6, in the illustrated embodiment. The knob markings340can further comprise raised structures, as illustrated, which can further be enhanced with contrasting colors for easy visualization. The number of facets can range from about three to about 100.

The knob314can further comprise one or more complementary structures affixed or integral thereto, such as a plurality of protrusions338that fit into detents336affixed or integral to the proximal end of the hub body302. Such protrusions extending into detents in the hub body302can provide a ratcheting or clicking sound as well as providing resistance to inadvertent movement of the knob314once it is rotated to the correct location. The knob314, in some embodiments, can be biased toward the hub body302to ensure that complementary structures such as the protrusions and detents come into correct contact. In other embodiments, the knob314can comprise a ratchet system to further control its rotary movement with respect to the hub body302. In other embodiments, the knob314can comprise one or more detents (not shown) while the hub body302can comprise one or more complementary protrusions (not shown). It is beneficial that the knob314be moved only when required by the user and not by accident or not when it is required to maintain its rotary position and, by consequence, the curvature at the distal end of the tubing. The number of ratchet locations, or low energy positions or setpoints, can range from about 2 per 360 degree rotation to about 20 with a preferred number of ratchet locations ranging from about 4 to about 12.

The hub body302can be fabricated from biocompatible metals such as, but not limited to, stainless steel, titanium, nickel coated brass, cobalt nickel alloy, and the like, although it could also be fabricated from polymeric materials in a less expensive format. In the polymeric materials embodiment for the hub, the outer tube can be affixed to a jackscrew, which is trapped longitudinally and rotationally within the hub body302, and the inner tube can be affixed to an anchor, which is embedded into the hub body302. The knob314can be fabricated from the same metals as the hub body302but it can beneficially be fabricated from biocompatible polymers such as, but not limited to, polyamide, polyimide, polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS), acetal polymers, polycarbonate, polysulfone, PEEK, Hytrel®, Pebax®, and the like. The petcock304and petcock handle308can be fabricated from the same materials as the knob314, or it can be different materials. The jackscrew body (or traveler)316can be fabricated from the same materials as the hub body302, or from different materials, but must be able to be strongly affixed to the outer tube102.

The arrow pointer310can be affixed, or integral, to the hub body302or other component. The arrow pointer310is used to indicate the direction of bending or deflection at the distal end of the steerable microcatheter by reference points on the hub but due to torsional effects on such a long device as a microcatheter, the primary guide for orientation will be the fluoroscopic or X-Ray images taken of the distal end of the steerable microcatheter, in vivo. The hub system300illustrated inFIG.3is not detachable or releasable from the proximal end tubes110and104. In other embodiments such as that ofFIG.1, the hub system300can be made to slide onto the tubes110,104and clamp by means of locking mechanisms. In yet other embodiments, the hub300can be made to split open along its axis and then re-close and latch over the proximal ends of the tubes110,104.

FIG.4illustrates a side view, in partial breakaway, of an embodiment of a distal end400of a steerable microcatheter. The distal end400comprises the distal outer tubing102further comprising the lateral partial slits216and the intermediate (or inner) tubing104further comprising the longitudinal slit226and the distal inner tube tip230. A weld402affixes the distal end of the outer tubing102to the connected side232of the intermediate tubing. The distal end400can further comprise one or more separate radiopaque markers404, which may or may not comprise a central lumen. The distal end can also comprise a tip coil406to reduce any chance of trauma caused by advancing the distal end against tissue. The tip coil406can be affixed to the distal tip230by swaging, adhesives, welding, connectors, or the like. The tip coil406can comprise regular coil pattern or a variable coil pattern. In a preferred embodiment, the most distal part of coil406can comprise wider coil spacing than the more proximal part.

Referring toFIG.4, distal outer tube102and the inner tubing104are rotated about the longitudinal axis such that the connected side232of the inner tube104is generally aligned with, and affixed or welded402to, the distal outer tubing102on the side comprising the partial lateral slits216. The width of the partial lateral slits, T-slots, H-slots216, and the longitudinal slot226can range from about 0.001 to about 0.050 inches with a preferred range of about 0.001 to about 0.010 inches and more preferably from about 0.0015 to about 0.005 inches. In the illustrated embodiment, the slits216, and226are about 0.010 inches. The width of the partial lateral slits216on the outer tube102can be used, in compression to provide at least some limit to how much the distal outer tube102can bend in compression along the side comprising the partial lateral slits216. Note that the inner tube104may extend beyond the distal end of the distal outer tube102. In the illustrated embodiment, the inner tube104extends about 5-mm to about 20 mm beyond the distal end of the distal outer tube102. This construction provides for reduced device complexity, increased reliability of operation, and reduced manufacturing costs relative to other steerable devices. The steerable microcatheter, in the embodiments presented herein, has high column strength, and resistance to torque.

The distal end400of the steerable microcatheter can be generally fabricated from metals with sufficient radiopacity or radio-denseness that they are clearly visible under fluoroscopic or X-ray imaging. However, if this is not the case, additional radiopaque markers404can be affixed to the outer tube102, the inner tube104, or both. These radiopaque markers404can comprise materials such as, but not limited to, tantalum, gold, platinum, platinum iridium, barium or bismuth compounds, or the like. The radiopaque markers404can be beneficially oriented in an asymmetrical manner, as illustrated, to denote the direction of bending to an observer viewing an X-ray image of the distal end400. The tip coil406can comprise materials such as, but not limited to, nitinol, stainless steel, tantalum, platinum, platinum iridium, and the like. The tip coil406can thus function as a radiopaque marker as well as an atraumatic distal end feature.

Close tolerances between the internal diameter of the outer tube102and the outside diameter of the inner tube104, ranging from a radial gap of between about 0.0005 inches to about 0.008 inches, depending on diameter cause the two tubes102and104to work together to remain substantially round in cross-section and not be ovalized, bent, kinked, or otherwise deformed. This is especially important in the flexible distal region comprising the partial lateral cuts216on the distal outer tube102and the longitudinal slot226in the inner or inner tube104. The two tubes102and104can be fabricated from the same materials or the materials can be different for each tube102,104. Materials suitable for tube fabrication include, but are not limited to, stainless steel, nitinol, cobalt nickel alloy, titanium, and the like. Certain very stiff polymers may also be suitable for fabricating the tubes102,104including, but not limited to, polyester, polyimide, polyamide, polyether ether ketone (PEEK), and the like. The relationship between the inner tube104, the distal outer tube102, and the slots216,226,228serve to allow flexibility and shaping in high modulus materials such as those listed above, which are not normally suitable for flexibility. The internal and external surface finishes on these tubes102,104are preferably polished or very smooth to reduce sliding friction between the two tubes102,104because of their very small cross-sections and their relatively long lengths. Lubricants such as, but not limited to, silicone oil, hydrophilic hydrogels, hydrophilic polyurethane materials, PFA, FEP, or polytetrafluoroethylene (PTFE) coatings can be applied to the inner diameter of the distal outer tube102, the outer diameter of the inner tube104, or both, to decrease sliding friction to facilitate longitudinal relative travel between the two tubes which is necessary for articulating the flexible, slotted region near the distal end400of the articulating, deflectable, or steerable microcatheter. The exterior surface of the distal outer tube102can be covered with a polymeric layer, either substantially elastomeric or not, which can cover the slots216, etc. and present a smoother exterior surface to the environment as well as optionally maintaining a closed fluid path through the lumen of the microcatheter. The exterior surface can be affixed or configured to slip or slide over the exterior of the outer tube102.

The weld402affixes the distal outer tube102to the intermediate or inner tube104such that they cannot move relative to each other along the longitudinal axis at that point. However, since the two tubes102,104are affixed to each other on the side of the distal outer tube102containing the partial lateral slots or gaps216, compression or expansion of those gaps216can be accomplished by moving the weld402by relative movement of the inner tube104and the outer tube102. The weld transmits the force being carried by the connected side232of the inner or intermediate tube104to the slotted side of the distal outer tube102. Note that the terms intermediate tube104and inner tube104are used interchangeably, by definition. The inner tube104becomes an intermediate tube104if another tube, wire, stylet, or catheter is passed through its internal lumen224.

In other embodiments, since the inner or intermediate tube104is split226lengthwise in the flexible region, a portion, or the entirety, of the distal end of the inner tube104can be affixed, adhered, welded, fastened, or otherwise attached to the distal outer tube102and functionality can be retained. The distal end230of the inner tube104can, in some embodiments be retained so as to create a cylindrical distal region230in the inner tube104and this entire cylindrical distal region230, or a portion thereof that does not project distally of the distal end of the outer tube102can be welded to the outer tube102around a portion, or the entirety of the circumference of the outer tube102. If only a portion of the inner tube104is welded to the distal outer tube102, then the weld is beneficially located, approximately centered, on the side of the distal outer tube102comprising the partial lateral slots216. The cylindrical distal region230is a beneficial construction, rather than completely cutting the inner tube104away on one side, since the distal region230projects distally of the distal end of the distal outer tube102to form the tip of the steerable microcatheter further comprising an atraumatic distal end. The tip coil406can be affixed to the distal outer tube102, the distal end230of the inner tube104, or both, using methodology such as, but not limited to, fasteners, welds, adhesive bonding, and the like.

In some embodiments, one of the welds, all of the welds, or a portion of the welds can be completed using techniques such as, but not limited to, TIG welding, laser welding, silver soldering, fasteners, adhesives, plasma welding, resistance welding, interlocking members, or a combination thereof. Laser welding is beneficial because it is highly focused and can be located with high accuracy. These welds include the weld402at the distal end that connects the inner tube104and the distal outer tube102as well as the welds at the proximal end connecting the inner tube104to the hub and the distal outer tube102to the traveler of the jack-screw316.

FIG.5illustrates an oblique external view of an embodiment of the proximal end500of the steerable microcatheter comprising the outer tube110, the knob314, the hub body302, the arrow pointer508further comprising the pointed end504, a stopcock body506, the petcock304, the petcock handle308, and the Luer fitting312further comprising a locking flange502. In this embodiment, the hub can be configured to be removable or it can be configured to be permanently affixed to the proximal end of the outer proximal tubing110and the inner tubing104(not shown).

Referring toFIG.5, the pointed end504of the arrow pointer508can be integrally formed with the arrow pointer508, or it can be affixed thereto. The arrow pointer508, which is optional, can be integrally formed with the hub body302, or it can be affixed thereto using fasteners, welds, adhesives, brazing, soldering, or the like. The stopcock body506can be integrally formed with the hub body302or it can be affixed thereto using fasteners, welding, soldering, brazing, adhesives, threads, bayonet mounts, or the like. Referring toFIGS.3and5, the lumen of the Luer fitting312is operably connected to the through bore of the petcock304if the petcock304is aligned therewith (as illustrated), or the petcock304can be rotated about an axis to misalign the through bore of the petcock304with the Luer fitting312and prevent fluid flow or passage of solid material therethrough. The knob314can be round, shaped as a lever, it can comprise knurls, facets (as illustrated), or it can comprise a plurality of projections which facilitate grabbing and rotation by the user. Circumferential motion of the knob314about is longitudinal axis is preferably and beneficially smooth but with sufficient friction to maintain its position in any desired configuration.

FIG.6illustrates an embodiment of the distal end400of the steerable microcatheter in a curved configuration. The distal end400comprises the distal outer tube102, the inner tube104, the outer tube lumen214, the plurality of outer tube longitudinal cuts or slots218, and the plurality of outer tube partial lateral cuts216.

Referring toFIG.6, the outer tube partial lateral cuts216represent spaces that close up when the side of the tube in which the lateral cuts216are located is placed in compression. Such compression is generated by pushing the outer tube102distally relative to the inner tube104. When the partial lateral cuts216gaps close, further compression is much more difficult because the outer tube102stiffens substantially when no further gap exists for compression. The composite structure, with the intermediate tube104nested concentrically inside the outer tube102is relatively stiff and resistant to kinking no matter what amount of curvature is being generated.

Preferred radius of curvatures for the distal end can range from about 0.20 inch to about 6 inches, with a preferred range of about 0.25 inches to about 2 inches and a more preferred range of about 0.3 to about 1.5 inches. The radius of curvature need not be constant. In some embodiments, the proximal end of the flexible region can have the partial lateral cuts216spaced more widely than those at the distal end of the flexible region, causing the distal end to bend into a tighter radius than, the proximal end of the flexible region. In other embodiments, the distal region can be less flexible than the proximal end of the flexible region.

The partial lateral cuts216, and the “T”-slots in the outer tube102are beneficially treated using etching, electropolishing, passivation, sanding, deburring, machining, or other process to round the external edges of the partial lateral cuts216. Thus, the edges are blunted or rounded so they are not sharp such as to cause the steerable microcatheter to dig, skive, or shave material from the inside of a catheter, dilator, or obturator.

FIG.7Aillustrates a top view of another embodiment of an outer tube700in the region of the distal, flexible section, wherein the outer tube700comprises a plurality of partial lateral cuts or slots706further comprising a dovetail702. The dovetail702creates a groove702and further comprises a peg or projection704that rides or is circumferentially constrained within the groove702as long as the outer tube700is neutrally forced, or forced in compression on the side of the partial lateral cuts or slots706. The projection704riding within the dovetail groove702provides for torque resistance and torsional rigidity in the area of the dovetail702.

FIG.7Billustrates a side view of the outer tube700in the region of the distal, flexible section, wherein the outer tube700comprises the partial lateral slots706, the dovetail702further comprising the projection704, and the “T” slots218. The T-slots218are optional or they can be configured differently.

The steerable microcatheter can be used in the cardiovascular system, cerebrovascular system, the pulmonary system, the gastrointestinal system, or any other system comprising tubular lumens, where minimally invasive access is beneficial. The steerable microcatheter of the present inventions is integral and steerable. It is configured to be used with other catheters or guidewires that may or may not be steerable, but the steerable microcatheter disclosed herein does not require external steerable catheters or catheters with steerability to be steerable as it is steerable or articulating on its own. The steerable microcatheter is capable of bending and unbending a practically unlimited number of times. The steerable microcatheter is especially useful with catheters that are not steerable since the steerable microcatheter comprises its own steering system.

The steerable microcatheter can be removed from the lumen of a catheter following completion of its task. Without removal of the steerable microcatheter, the lumen is compromised and the capacity of the sheath to introduce catheters is reduced, given a certain outside diameter. This device is intended for use with catheters and is not intended for use as integral to a catheter. The steerable microcatheter device steers itself and can steer a catheter but is not a replacement for a steerable catheter.

The steering mechanism disclosed herein can be used to steer other types of catheters, guide catheters, introducers, sheaths, guidewires, punches, needles, or even obturators that are placed within the aforementioned devices, with high degree of control over long lengths up to 250 cm or more while requiring less wall thickness and thus allowing for larger internal lumens than steerable devices of the prior art with the same outside diameter. Typical sheaths can have internal lumens with capacities of, for example, 3-Fr to 12-Fr and still maintain very thin walls of around 1-Fr. While smaller catheters or guide catheters with lumens in the range of about 2-Fr to 5-Fr can have even smaller wall thicknesses, depending on the materials used to construct the walls of the sheath. Some sheath constructions can comprise composite materials such as an inner tube fabricated from metal and an outer tube fabricated from metal with a polymeric exterior coating. The inner tube can further be coated with an interior liner of, for example PTFE, or other fluoropolymers (PFA, FEP), Parylene, Pebax®, Hytrel®, polyimide, polyamide, PET, or the like, to create certain reduced frictional properties, electrically insulating properties, or both. These coatings or liners can range in thickness from about 0.0001 to about 0.005 inches, with a preferred thickness range of about 0.0005 to 0.002 inches.

The steering mechanism disclosed herein, comprising two or more nested axially elongate cylindrical tubes moving relative to each other only along the longitudinal axis, can provide a high degree of precision, repeatability, force, column strength, torsional control, and the like, in a configuration with extremely thin walls and large inside diameter (ID) to outside diameter (OD) ratio. One of the tubes comprises partial lateral cuts or complex lateral gaps and the other tube comprising a split running substantially the length of the flexible region. The disconnected side of the slit tube can be removed so that only a partially formed, connected side remains. However, in preferred embodiments, the disconnected side, which is actually retained at the distal end, is not removed but serves to fill space within the lumen of the outer tube102to prevent kinking, improve column strength, prevent lumen collapse and provide for guiding of central stylets or catheters. Prior art devices require greater wall thickness, which reduces the size of the internal lumen relative to a given outside diameter, or they do not have the same degree of precise movement at the distal tip under control from the proximal end of the device.

FIG.8illustrates a side view of the distal end400the steerable microcatheter advanced through a central lumen812of a dilator or obturator810of a guide catheter814(not shown). The steerable microcatheter distal end400comprises the outer tube102, comprising the plurality of partial lateral cuts216, and the inner tube104, comprising a distal end220. The distal end220comprises, or is terminated by a rounded, blunted, atraumatic distal end806. The steerable microcatheter400can further comprises a central lumen (not shown).

In some embodiments, the outer tube102can be modified to adjust stiffness. It can be preferential to increase the resistance to bending moving distally to proximally on the outer tube102. This increase in bending resistance contravenes the tendency of the outer tube to bend more severely at the proximal end of the flexible region than in the distal region. It is possible to configure the bending so that the bend radius is approximately constant or such that a greater curvature (smaller radius of bending) is generated moving toward the distal end of the bendable region. The partial lateral slots216can be cut with reduced depth more proximally to increase the resistance to bending imparted by the outer tube102. The partial lateral slots216can be cut more narrowly in the more proximal regions to reduce the distance the slot216can close. The T-slots218can be reduced in length or removed in the more proximal regions of the flexible region of the outer tube102. Elastomeric bumpers or fillers can be added to some of the partial lateral slots216to reduce the amount the partial lateral slots216can compress. Once the partial lateral slots216, associated with the T-slots218have closed under bending of the outer tube102, further bending is resisted and is substantially arrested. By tailoring the width and spacing of the partial lateral slots216, a specific final curvature can be tailored for a given catheter.

FIG.9Aillustrates the outer tube102comprising the lumen214, the proximal tube wall212, the plurality of partial lateral slots216, the plurality of T-slots218, a short partial lateral slot902, a slightly longer partial lateral slot904, and a standard length lateral slot216but with a shortened T-slot906.

Referring toFIG.9A, the most proximal partial lateral slot902penetrates less than the standard partial lateral slots216. The second (moving distally) partial lateral slot904is slightly longer than slot902and therefore is more flexible in that region and requires less force to generate bending. The third partial lateral slot comprises the shortened T-slot906which reduces the ability of the tubing to bend given a constant bending force. The T-Slot218is a modification of the partial lateral slot216which comprises a substantially axial component of the slotting, which serves to reduce localized bending stress and an associated reduced risk of yield.

FIG.9Billustrates the inner tube104comprising the lumen224, the proximal region222, the connected side232, the distal end230, and a beveled lead-in910at the proximal end of the distal end230.

Referring toFIG.9B, the proximal end of the disconnected region can be moved distally to increase the stiffness of the inner tube104in a specific region, generally the most proximal part of this distal, flexible region.

In certain preferred embodiments, it is beneficial that the inner tube104can sustain compression to generate bending of the outer tube102at the distal end back to straight after being curved and even to bend beyond straight in the other (or opposite) direction. In order to sustain compression, it is beneficial that the disconnected side234be separated from the connected side232at or near substantially the center or midpoint of the tubing. Depending on the width of the slot226separating the disconnected side234from the connected side232, the location of the slot can be offset from the midpoint but this is dependent on the wall thickness of the inner tube104and the angle of the slotting. In a preferred embodiment, interference exists between the disconnected side234and the connected side232such that the disconnected side and force transmitting member cannot move substantially inward, a situation that would have negative effects of obstructing the lumen, restricting fluid flow therethrough, trapping stylets or other catheters that need to move longitudinally therein, or buckling sufficiently to prevent application of longitudinal compression forces on the connected side232.FIG.10Aillustrates a lateral cross-sectional view an inner tube104nested inside an outer tube102and separated from the outer tube104by a radial gap1002in the flexible region of a steerable microcatheter wherein the inner tube104is separated by a split or gap226into two approximately or substantially equal parts, a connected side232and a disconnected side234, approximately (or substantially) at the midline or centerline of the cross-section.

FIG.10Billustrates a lateral cross-sectional view an inner tube104nested inside an outer tube102and separated from the outer tube104by a radial gap1002in the flexible region of a steerable microcatheter wherein the inner tube104is separated by a split or gap226into two substantially unequal parts, a connected side232and a disconnected side234, substantially offset from the midline or centerline of the cross-section.

Referring toFIGS.10A and10B, the disconnected side734is retained in close proximity to the outer tube702by its stiffness and its inability to deform such that the edges of the disconnected side734can pass beyond the edges of the connected side732and thus the two sides732and734are retained radially displaced from centerline. If the gap726were too large or either side732,734were small enough to fit within the edges of the other side, then displacement of one side toward the centerline and confounding of the off-center orientation of the connected side732or734would occur leading to buckling of the connected side732in compression and inability to straighten out a bent steerable microcatheter. Another problem might be loss of torqueability and predictability of the direction of bending. Both embodiments shown inFIGS.10A and10Bmaintain circumferential and radial orientation of the inner tube connected side732relative to the disconnected side734and promote high precision deflection of the distal tip. The structures illustrated inFIGS.10A and10Bare preferably configured with a minimum area moment of inertia in the bending direction while maintaining sufficient cross section as to allow for steering, pushability and torqueability.

In preferred embodiments, the radial gap1002is minimized and is retained between about 0.0005 to 0.002 inches when the steerable microcatheter is about 0.035 inches in outside diameter. Furthermore, the split or gap726should be as minimal as possible and in preferred embodiments can range from about 0.0005 inches to about 0.003 inches with a gap of about 0.0005 to 0.02 inches being most preferable.

FIG.11illustrates a side, partial breakaway view of the distal end of a steerable microcatheter1100as well as a portion of the intermediate region. The steerable microcatheter1100comprises the inner tube104, the coiled intermediate outer tube108, the distal outer coil1102, the backbone1104, the polymeric outer coating106, and the distal coil spaces1110.

The polymeric outer coating106can extend the entire length of the steerable microcatheter1100(or100) or it can extend only over a portion of the length and can correspond to certain sections such as the proximal section, one or more intermediate section108, the distal region1102, or a combination thereof. The polymeric outer region can comprise an elastomer such as, but not limited to, Hytrel, PET, polyimide, Pebax, polyurethane, silicone rubber, or the like, and can be coated with an additional anti-friction coating such as, but not limited to, silicone oil, silicone grease or gel, hydrophilic hydrogel, fluoropolymer, polyimide, or the like.

The distal coil1102is affixed, at its proximal end, to the distal end of the intermediate coil108. The inner tube104is affixed to the distal coil1102such that most or nearly all the distal coil is controlled in expansion and contraction by the inner tube104. The distal coil1102comprises the spaces1110which can range in magnitude from 0.0005 inches to about 0.020 inches or greater. In the illustrated embodiment, the coil spaces1110are about equal in width to the coil element diameter. The coil element diameters can range from about 0.0005 inches to about 0.010 inches and preferentially ranges from about 0.001 inches to about 0.007 inches in diameter. The coil materials can comprise materials such as, but not limited to, nitinol, polyimide, stainless steel, titanium, cobalt nickel alloy, or the like. The coil materials beneficially comprise material properties of low malleability and high spring hardness. The distal coil1102can be fabricated from flat or round wire.

Referring toFIGS.11and2, the backbone1104is located on the side234of the steerable microcatheter1100where the inner tube104is disconnected from more proximal structures. Thus, axially oriented forces transmitted through the connected side232cause the spring coil1102to compress or expand longitudinally with more freedom and less restriction on the connected side232, as imposed by the backbone1104, than on the disconnected side234. This results in an asymmetric force loading on the distal end and causes the distal end to deflect away from the longitudinal axis under control from the proximal end of the steerable microcatheter1100.

FIG.12illustrates the distal end of a steerable microcatheter1200comprising the inner tube104further comprising the longitudinal slot226, the proximal-to-distal-intermediate outer tube108, the polymeric fluid barrier covering118, the slip layer106, a distal outer tube1202further comprising a plurality of lateral gaps1210, a radiopaque marker1212, and a backbone1208.

Referring toFIG.12, the distal outer tube1202can be fabricated as a tube comprising the slots1210or gaps that are imparted by way of EDM, wire EDM, laser cutting, photochemical etching, conventional machining, or the like. The proximal end of the distal outer tube1202is affixed to the distal end of the intermediate outer tube108. The distal end of the distal outer tube1202is affixed to distal end of the inner tube104substantially distal to the distal end of the longitudinal slot226to prevent rotational and lateral relative movement at that point. The backbone1208forces asymmetric lengthening and compression of the gaps1210thus generating a lateral bend or curve out of the longitudinal axis in the distal outer tube1202when the inner tube is tensioned relative to the outer tube. The radiopaque marker1212is a cylindrical thin walled band, illustrated swaged into a circumferential groove at the distal end of the system.

FIG.13Aillustrates a side view of the inner tube1300of a steerable microcatheter. The inner tube1300comprises a proximal tube1302, a distal bendable region1304, further comprising a longitudinal slot1306, a distal end tube1308, a central lumen1310, a plurality of flex enhancing cutouts1316. Inner tube1300may also comprise an optional intermediate hyperflexible region1320which is detailed inFIG.13B.

The flex enhancing cutouts1316can be disposed to open into the longitudinal slot1306or they can be disposed to open (not shown) to the exterior of the tube and not communicate with the longitudinal slot1306, or be a combination thereof. The hyperflexible region1320can extend from about adjacent to the proximal end of the longitudinal slot1306to a region about 5, 10, 15, 20, or even 50-cm from the distal end of the inner tube1300.

FIG.13Billustrates a magnified view of the hyperflexible region1320further comprising slots1322and1324oriented in at least two different directions.

Referring toFIG.13B, the slots1324and1322are radially offset from each other, and, as illustrated, are oriented orthogonally to each other. Each slot1324and1322may comprise one of a pair of slots coming in from the lateral direction to end in a central connector region (bridge1314) that is not substantially favorable in bending to any particular direction and is still able to transmit compressive force, tensile force, and torque about the primary longitudinal axis. Thus the inner tube1300can bend around relatively sharp radii and still allow for inner tube movement relative to the outer tube to generate steering functionality. In the illustrated embodiment, the slots1322and1324arranged in repeat patterns of first1322and then1324, after which the pattern repeats. This pattern could be modified to allow two or more of the same orientation slots to be grouped together. Furthermore, patterns could be applied that are oriented at other angles, for example 45 degrees, to the slots1324and1322, thus providing additional or different flexibility.

FIG.13Cillustrates a lateral cross sectional view of inner tube1300at slot1322, showing the lumen1310, the bridge material1314, and the slot1323. The bridge material1314is preferably integral to the tubing1402and is formed by material being removed by laser cutting, EDM, or the like. The cross-sectional area of the bridge material needs to be sufficient to prevent failure, or preferably even yield when the outer tube1400is placed in tension or compression. For example, with stainless steel, which can have a tensile strength of, for example, 200,000-PSI, the cross sectional area will need to be sufficient to prevent yield or failure with a tension of, for example, 1 pound of force. Of course safety factors, usually 1.5 or higher, are always important, especially since the bridge material1314will also undergo torsion when the tube is bent or flexed.

FIG.14illustrates a side view of an outer tube1400further comprising a base tube1402having a lumen1420(not shown), a distal steering flex region1404further comprising a series of uniformly oriented slots1408, and at least a first intermediate region1406further comprising a series of cutaways or slots1410,1412,1414, and1416.

Referring toFIG.14, the slots1410,1412,1414, and1416are arranged in a repeating sequence of 4 differently oriented slots extending the length of outer tube sufficient to allow for hyperflexibility. The hyperflexible region can comprise these slot patterns or the slot sequence and patterns comprising a repeating sequence of 2 (two) differently oriented slots extending the length of outer tube which are the same as those shown inFIG.13B(every other slot pair oriented radially 90° about the tube relative to an adjacent slot pair). The hyperflexible region can begin just proximal to the proximal end of the steering region1404and extend from 5 to 50 cm, or more, proximal to the proximal end of the bending region1404. The number, spacing, and width of the lateral cuts can be pre-determined to allow for bending to a radius of curvature sufficient to track through specific vessels. Examples of some of the most tortuous vessels include the carotid siphon in the neck, which can have radii of curvature as small as 0.5-cm or less.

Further referring toFIG.14, the distal steering region1404comprises a series of partial lateral cuts that can be terminated with a “T” or they can have no longitudinal component. The longitudinal component, which forms a “T” or an “H”, depending on your point of view, helps to distribute stresses and minimizes the risk of yield when the device is curved. The device curves by allowing the slots1408, in the steering region, to close or open, thus the steering occurs in one plane lateral to the longitudinal axis of the microcatheter. The width and number of partial lateral cuts in the steering region1404can be pre-determined to allow for bending through a certain minimum radius.

Thus, as described in relation toFIGS.13A and14, the steerable catheter comprises an outer tube having an outer tube wall, proximal end, a distal end and a lumen extending through the outer tube. The outer tube may be characterized by a distal segment, a proximal segment and a middle segment located between the distal segment and the proximal segment; and an inner tube having an outer tube wall, proximal end, a distal end and a lumen extending through the inner tube. The inner tube may also be characterized by a distal segment, a proximal segment and a middle segment located between the distal segment and the proximal segment. The inner tube is disposed within the outer tube such that the inner tube distal segment is disposed within the outer tube distal segment, the inner tube middle segment is disposed within the outer tube middle segment, and said inner tube proximal segment is disposed within the outer tube proximal segment. The inner tube is longitudinally fixed to the outer tube near the distal end of the outer tube, near the distal end of the outer tube distal segment. A hub is affixed to the proximal end of the inner tube and outer tube, and is operable to tension or compress the inner tube relative to the outer tube (or vice versa) to cause bending of the outer tube distal segment. To provide steering functionality, the outer tube has a first plurality of laterally oriented slots extending partway through the outer tube distal segment, wherein said first plurality of laterally oriented slits are aligned on one circumferential side of the outer tube thereby defining a spine running along a side of the tube opposite the slots and the inner tube wall has a longitudinal slot that divides the inner tube distal segment along a longitudinal axis. To provide extra flexibility to the structure in the middle segment, while maintaining column strength and tensile strength, the outer tube middle segment has a second plurality of laterally aligned slots extending partway through the outer tube, said second plurality of laterally aligned slots being non-aligned circumferentially, and the inner tube middle segment has a third plurality of laterally aligned slots extending partway through the inner tube, said second plurality of laterally aligned slots being non-aligned circumferentially. The longitudinal slot of the inner tube divides the tube into two axially oriented parts which are connected at the distal end of the inner tube, and one of said axially oriented parts includes a plurality of flex enhancing cutouts dispersed axially along said axially oriented part. The cutouts may be dispersed axially along an inner portion of said axially oriented part. The second plurality of slots are arranged in longitudinally aligned pairs, in a repeating pattern of a four differently oriented slots, or longitudinally aligned and radially dispersed pairs of slots, dispersed along the outer tube middle segment. The third plurality of slots (on the inner tube) are arranged in pairs, in a repeating pattern with a first pair of slots radially offset from a second pair of slots.

The hub can include an internal lumen capable of receiving a jack-screw traveler element or other actuator and preventing said jack-screw traveler element or actuator from rotating about the longitudinal axis of the hub, wherein the inner tube is constrained not move relative to the hub; a knob or other control mechanism configured for engagement with the jackscrew traveler element or actuator; and wherein the jack-screw traveler element or actuator affixed to the proximal end of the one of the outer tube or the inner tube, wherein the jack-screw traveler element or actuator comprises a traveler thread on at least a portion of a surface, and further wherein the inner tube can tensioned or compressed relative to the outer tube in response to movement of the jack-screw traveler, or wherein the outer tube can tensioned or compressed relative to the inner tube in response to movement of the jack-screw traveler.

Preferably, the slots in the middle segment of each tube are arranged to enhance flexibility in the middle segment of the microcatheter while avoiding a preferential off-axis bending, so that the middle segment will bend in any direction without preference to a particular bending direction or resistance to a particular bending direction. This may be accomplished by locating the pairs of slots1322,1323(and resultant bridges1314) in the inner tube middle segment relative to slots1412(or pairs of slots) in the outer tube middle segment such that slot pairs in the inner tube are radially displaced from slots, or slot pairs, in the outer tube. In other words, the plurality of laterally oriented slots in the outer tube middle segment defines a bridge portion of the outer tube middle segment and is longitudinally aligned with one of the pairs of laterally oriented slots in the inner tube middle segment which define bridges in the inner tube middle segment, and disposed outer tube middle segment such that the bridge portion is circumferentially displaced from the bridge portions of the inner tube middle segment.

In some embodiments, instead of having the inner tube or rod cut into a control rod and a keeper or stay, the stay or keeper can be eliminated and the inner tube or rod separated into two or more control rods that can be affixed to the apparatus at a point distal to the bendable region. The proximal ends of the control rods extend all the way into the hub and are affixed to separate actuators, which can be jackscrews, hydraulic actuators, pneumatic actuators, magnetic actuators, or the like. Since the distal end of the device can have various bending characteristics and symmetry, it is beneficial that each control rod have a separate actuator that can move at different axial distances given a single control input by the user. For example, two jackscrews can comprise different thread pitches to accommodate off-center motion at the distal bendable region. Thus a push-pull force balance is applied to the distal end to enhance the amount of flexural modulus and increase the bending forces that can be generated by the system. Control rods that are not used or actuated at the proximal end can serve as keepers or stays to maintain the radial position of the control rods in an off-center configuration.

The embodiments presented herein describe a system that does not use pull wires. No side lumens are required in either the outer tube or the inner tube. Such side lumens, as found in certain prior art catheters, require extensive cross-sectional area be used to surround the side lumens and take away from the potential area for the central lumen since the outside extent of the catheter is limited. The use of pull wires requires such as those in certain prior art catheters, retaining these structures along one side of the outer tube may be difficult or impossible. Side lumens or channels are necessary to retain a pull wire or control rod in the correct location so as to provide correct off center forces to bend the distal end. The side lumens are also necessary to keep the control rod or pull wires out of the central lumen which needs to remain open and substantially circular. The system disclosed herein, however, retains a high degree of column strength, maximum torqueability, the largest possible central lumen, and a very strong control and steering function or capability. Furthermore, the side lumens or channels are necessary to maintain spatial (rotational orientation) for the articulating distal end of the device. Without the side lumens or channels permitting axial slidability but generating radial retention, the pull wires or pushrods would be free to migrate around within the central lumen of the device and could bend the device in an unwanted direction. Long microcatheters with relatively small cross-sectional areas are highly subject to torque and rotational misalignment and some method must be employed to retain the correct circumferential location of the articulating apparatus. It is possible, however to divide the central lumen into one or more channels thus forming a dual lumen microcatheter, a tri-lumen microcatheter, a quad lumen microcatheter, or the like.

Furthermore, a pull-wire as used in prior art devices is incapable of generating compression against the distal end of the device so a pull-wire could not, under compression, move or articulate the distal end of the device. The pull-wire, under tension, can move or articulate the distal end and would require some sort of counterforce such as an opposing pull-wire, shape memory metal, or spring return biasing to move the distal end in the reverse direction.

However, a tubular or cylindrical (substantially no lumen) central control device can maintain its structure in compression, maintain circumferential location within the outer cylindrical, axially elongate tube, maintain precise control, maintain sufficient tensile strength to exert forces, and maintain a central lumen larger than any other type of steerable device. The resistance to buckling occurs even when the inner tube is slotted longitudinally because the inner tube is constrained within the outer tube using very tight tolerances that will not let the inner tube bend out of its straight orientation, even under compression.

The present inventions may be embodied in other specific forms without departing from its spirit or essential characteristics. These devices lend themselves to motorized control and robotic control. The motorized or robotic control can be wholly exercised by a human operator, partially by the human operator and artificial intelligence (AI), or wholly by AI. The motorized system can be powered using linear actuators, stepper motor systems, pneumatics, hydraulics, magnetic couplings, and the like. Feedback can comprise fluoroscopic imaging systems, ultrasound imaging systems, magnetic resonance imaging systems, PET scans, X-ray based imaging such as fluoroscopy, and the like. Angiograms can be taken to help create roadmaps for catheter advancement. A catheter system such as this can generally be controlled using a longitudinal axis actuator, a rotary axis actuator, and a deflection actuator. Fine adjust systems can piggyback off of coarse system placement actuators and guides. The longitudinal axis travel can range from about 5-cm up to about 300-cm or more.

While the preferred embodiments of the devices and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the inventions. The elements of the various embodiments may be incorporated into each of the other species to obtain the benefits of those elements in combination with such other species, and the various beneficial features may be employed in embodiments alone or in combination with each other. Other embodiments and configurations may be devised without departing from the spirit of the inventions and the scope of the appended claims.