Patent Description:
Angioplasty is the technique of mechanically widening a narrowed or obstructed blood vessel, typically as a result of atherosclerosis. Angioplasty has come to include all manner of vascular interventions typically performed in a minimally invasive or percutaneous method.

Angioplasty guidewires may be used to guide stent catheters, for example, drug coated stents and/or bioabsorbable scaffolds to keep the vessels open following the procedure and/or to stretch stenoses more open.

In the current art, an empty and collapsed balloon placed at a distal tip of a catheter. The catheter riding on the guide wire, known as a balloon catheter, is passed into the narrowed locations and then the balloon is inflated to a fixed size using water pressures some <NUM> to <NUM> times normal blood pressure (<NUM> to <NUM> atmospheres). The balloon crushes the fatty deposits, opening up the blood vessel for improved flow, and the balloon is then collapsed and withdrawn.

An issue with the current art, is that the blood vessel is often totally occluded and quite seriously misshapen by the obstructions in the blood vessel. Insertion of a leading guidewire (e.g. <NUM> (<NUM>") and even thinner distal tip) is a mandatory step required in order to cross an obstructed coronary or peripheral vessel. Guidewire insertion is followed by balloon passage through the atherosclerotic lesion and subsequent dilatation. The guidewire takes a position within the lumen that defines a default/uncontrolled location of the distal tip (e.g. the site of least resistance) but this is not always the center of the lumen and/or the site of vessel occlusion needed for plaque penetration. Thus a balloon or micro-catheter led guidewire fails to be properly centered within the blood vessel. <CIT> discloses such vascular catheter with an expandable member.

According to one aspect of the present invention there is provided a microcatheter for insertion within a vessel as set forth in the appended claims.

The materials, methods, and examples provided herein are illustrative only and not intended to be limiting.

The invention is herein described, by way of example only, with reference to the accompanying drawings <NUM> to <NUM>, and 34A to 34D.

With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in order to provide what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. <FIG>, <FIG>, and <FIG>, as well as the corresponding passages of this description do not relate to embodiments of the claimed invention, but are for illustrative purposes only.

An aspect of some embodiments of the invention relates to a microcatheter having a deployment element at about the microcatheter tip, the deployment element is arranged to reversibly elastically expand at the microcatheter tip. Optionally, the deployment element is right at the tip, for example, overlapping the tip. Alternatively, the deployment element is distal (e.g., past) the tip. Alternatively, the deployment element is proximal to the tip. For example, using the distal end of the microcatheter as '<NUM>' reference, the deployment element is located, for example, at <NUM>, or about +/-<NUM> away from the tip (proximally or distally), or about +/-<NUM> away, or about +/-<NUM> away, or about +/-<NUM> away, or about +/-<NUM> away, or about +-<NUM> away, or about +/- <NUM> away, or about +/- <NUM> away, or other smaller, intermediate or larger distances away.

In an exemplary embodiment of the invention, the deployment element is arranged to substantially center the distal tip relative to the blood vessel. Optionally, the center is not symmetrical, for example, some deviation to either direction is tolerated. Optionally, the deployment element positions the distal tip within about the central <NUM>% of the blood vessel diameter, or about the central <NUM>% of the vessel diameter, or about <NUM>% of the vessel diameter, or about <NUM>% of the vessel diameter. Alternatively, in some embodiments, the deployment element is arranged to position the distal tip away from the center and towards the vessel wall, for example, to pierce lesions on the vessel wall.

In an exemplary embodiment of the invention, the deployment element is relatively long and arranged into one or more ribs. Optionally or additionally, the deployment element has relatively few contact points with the vessel wall. For example, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or other intermediate or larger number of contact points. Potentially, the combination of the long element and the few contact points allow for the deployment element to adjust to an uneven vessel wall surface, while potentially maintaining the centered and/or parallel position of the distal tip.

In an exemplary embodiment of the invention, the deployment element is changed from a collapsed state to an expanded state by relative motion of an outer tube and an inner tube. Optionally, the diameter of the deployment element is no larger than the outer diameter of an outer tube of the microcatheter. Optionally or additionally, the expanded state comprise an expansion outwards (e.g., towards the vessel wall) of the deployment element.

In an exemplary embodiment of the invention, the deployment element is adapted to push against the vessel wall with a force. Optionally, the force provides support for the distal tip of the microcatheter. For example, the distal tip is supported so that a guidewire can be pushed through a lumen in the microcatheter. Optionally, the force applied is enough to maintain the position of the distal tip while allowing insertion of the guidewire into an occlusion in the vessel. Not necessarily limiting examples of occlusions include plaques (e.g., extending inwardsly from the vessel wall), emboli (e.g., originating upstream that got stuck in the vessel), thrombus (e.g., clots formed inside the vessel lumen). Optionally or additionally, the applied force is not strong enough to damage the vessel wall.

In an exemplary embodiment of the invention, the deployment element stabilizes the distal tip of the microcatheter. Optionally, the distal tip of the microcatheter is stabilized when the guidewire and/or catheter tube is pushed through the lumen of the microcatheter. Optionally or additionally, the distal tip of the microcatheter is stabilized as the microcatheter tube and/or guidewire are pushed into the lesion in the blood vessel.

In an exemplary embodiment of the invention, the deployment element is disposed so that one or more lumens of the microcatheter are patent. Optionally, the deployment element is disposed at least partially along the outer circumference of the microcatheter.

In an exemplary embodiment of the invention, the deployment element is arranged to position and/or maintain the microcatheter tip parallel to the vessel wall.

In an exemplary embodiment of the invention, the deployment element is reversibly moved between the collapsed and expanded states multiple times. For example, when advancing through blood vessels.

In an exemplary embodiment of the invention, the deployment element comprises one or more resilient members in a resilient elastic structure that uses the resilience to press outwardly against the vessel walls.

According to the invention, the micro catheter comprises two tubes, an internal tube housing the guidewire, and an external tube for sliding through the blood vessel. Optionally, the outer tube is flexible. In an exemplary embodiment of the invention, a deployable element extends outwardly from the distal end of the microcatheter as will be explained. Optionally, a handle is placed at the proximal end of the guidewire for user control, for example, to deploy the deployable element.

In an exemplary embodiment of the invention, the shaping of the structure allows for even pressure in all directions of the vessel. The structure may be made of a shape memory material that can be shaped for the specific vessel prior to deployment, for example, for the coronary arteries, for the small vessels of the brain. The shape memory material may have a plateau deformation property. The material used may be a nickel titanium alloy such as nitinol. Nitinol is characterized by shape memory and superelasticity, and the nickel and titanium are present in roughly equal atomic percentages.

An aspect of some embodiments of the invention relates to a microcatheter with a deployment element on the microcatheter, the deployment element not being located within a lumen of the microcatheter. In an exemplary embodiment of the invention, the deployment element is sized and/or positioned to secure the microcatheter approximately in the middle of the vessel (e.g., blood vessel).

In an exemplary embodiment of the invention, the deployment element is exteriorly located relative to the lumens of the inner and/or outer tubes. Optionally, the deployment element is disposed along the outer surface of the microcatheter. Potentially, the lumens are free for other uses, for example, for insertion of guidewires, fluid delivery.

In an exemplary embodiment of the invention, at least a portion of the microcatheter tip can be displaced relative to the deployed deployment element, the displacement occurring while the deployment element maintains the position of a distal end of the microcatheter. Optionally, the inner tube of the microcatheter is displaced, for example, proximally and/or distally in an axial direction.

In an exemplary embodiment of the invention, the deployment element is deployed or retracted by lateral displacement of an inner tube relative to an outer tube. Optionally, the axial length change between the tubes is translated into changes in radial diameter of the deployment element. Optionally or additionally, the relative positions between the inner and outer tubes are lockable, for example, by a handle.

In an exemplary embodiment of the invention, the expansion in radial diameter is by a factor of about 2X, about 3X, about 4X, about 5X, about 6X, about 7X, about 8X, or other smaller, intermediate or larger expansion ratios. For example, in the compressed state, the outer diameter of the deployment element can be about <NUM>, and the outer diameter in the deployed state can be about <NUM>.

In an exemplary embodiment of the invention, the deployment element is located proximally to the tip of the microcatheter and does not deploy past the catheter tip. Alternative or additionally, the deployment element is angled in a proximal direction (e.g., away from the tip). Potentially, the location of the deployment element in the collapsed and/or expanded states allowed the microcatheter to be placed in close proximity to a lesion in the blood vessel.

An aspect of some embodiments - not according to the claimed invention and provided for illustration purposes only - relates to a method of traversing blood vessels using the microcatheter having the exteriorly located deployment device. Optionally, the vessels are tortuous, for example, the method allows passing through branch vessels having an angle (measured from the axis of the microcatheter distal end when moving forward) of, for example, greater than about <NUM> degrees, or greater than about <NUM> degrees, or greater than about <NUM> degrees, or other smaller, intermediate or larger angles. Not necessarily limiting examples of tortuous blood vessels include; coronary arteries, small arteries of the brain. Not necessarily limiting examples of the turning radius possible using the method include; about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or other smaller, intermediate or larger values.

In an exemplary embodiment - not according to the claimed invention and provided for illustration purposes only, the method comprises advancing the microcatheter having the deployment element at the distal end thereof across the torous anatomy. Optionally, the inner tube is advanced over a guidewire and across the tight turn. Optionally or additionally, the outer tube is advanced over the guidewire and around the tight vessel junction.

In an exemplary embodiment - not according to the claimed invention and provided for illustration purposes only, the method further comprises deploying the deployment element to secure the distal end of the microcatheter distally to the difficult anatomical location. For example, by relative motion of the inner and outer catheters.

In an exemplary embodiment - not according to the claimed invention and provided for illustration purposes only, the method further comprises advancing an outer sheath over the microcatheter and across the tortuous anatomy. Potentially, the outer sheath is passable around the tight turn due to the secured distal position of the microcatheter.

The principles and operation of an apparatus and method (not being claimed) according to the present invention may be better understood with reference to the drawings and accompanying description.

Reference is now made to <FIG>, which is a simplified schematic diagram showing a flexible micro-catheter <NUM> which consists of two main elements: a substantially elongate inner tube <NUM> and a distal deploying element <NUM>, in accordance with an exemplary embodiment of the invention. Optionally, the deploying element <NUM> is a resilient frame and/or a pre-shaped element in general which is preformed to frame a body lumen that it is intended to be used with. Optionally, these two elements are rigidly connected from two parts. Alternatively may be produced as an integrated single component. For example a laser may be used to cut around the tip of a nitinol tube to form the deployment element. A heat treatment process may be used to shape the tip to set it in its deployed state.

In an exemplary embodiment of the invention, the distal deploying element is made of a super-elastic material with shape memory, and/or a super-elastic material having a plateau deformation property, for example, Nitinol. In an exemplary embodiment of the invention, the shape memory is used to allow fold down of the deployment element after use.

In an exemplary embodiment of the invention, the tube and/or deployment element are placed and surround a guide wire, for example, the distal tip of the guidewire.

In an exemplary embodiment of the invention, the flexible micro-catheter <NUM> is used for passing through a vessel and/or for penetrating occlusions. The deployment element <NUM>, at the distal tip, may lead and support the guidewire while passing through the vessel, and enable the guidewire to pass occlusions, for example, occlusions that extend inwardly from the wall of the vessel, or occlusions that formed elsewhere and got trapped in the vessel.

In an exemplary embodiment of the invention, the deployment element has a structure in which one or more outwardly pressing ribs extend against the wall of the vessel. The rib or ribs are shaped as will be discussed in greater detail below, to apply pressure around the walls of the vessel. Optionally, even pressure is applied to the walls. In some embodiments, the ribs are part of a loop design or a helix, or the like.

<FIG> is a simplified schematic diagram of an embodiment of deployment element <NUM>, not forming part of the invention. <FIG> are side and front schematic views of the deployment element <NUM> of <FIG>. As shown, in some embodiments, the deployment element consists of three bars <NUM> which are connected with struts <NUM> arranged as a circumferential loop. The result is a blunt loop/circular like geometry which is therefore not harmful or traumatic for the vessel. In some embodiments, the round shape both presses evenly on the walls of the vessels and/or holds the guidewire rigidly at its center. More or less than three of the connecting bars <NUM> may be used in embodiments, for example, <NUM>, <NUM>, <NUM>, or other smaller, intermediate or larger numbers. Optionally, struts <NUM> are a single continuous rib formed into a loop around the circumference of the guidewire at the radius of the vessel. Optionally, the bars hold the vertices of the loop that are proximal to the guidewire.

A potential advantage of the design of <FIG>, is that the design permits a relatively short element that still has a substantial deployment ratio, and thus can be positioned near the occlusion.

<FIG> is a simplified schematic diagram which shows an external tube <NUM>. In <FIG> the external tube is shown alone. As further detailed in <FIG>, the external tube is assembled over inner flexible tube <NUM> carrying deployment element <NUM>. The external tube <NUM> is preferably made of conventional medical catheter materials, not necessarily limiting examples include; PTFE, PET, Polyurethane, Polypropylene, Polyamide, Polyethylene, Silicone, and may include reinforcing elements such as metallic coils, and/or radio-opaque elements such as gold/tungsten markers, barium- sulfate particles.

<FIG> is a simplified schematic diagram which shows the centralizing device in its deployed configuration in which the inner tube and guidewire are inside the outer tube and the deployment tip is deployed externally at the distal end, in accordance with some embodiments of the invention.

In some embodiments, the device is operated at its proximal end by forward driving button <NUM>, which is rigidly connected to flexible inner tube <NUM>, relative to handle <NUM>. In some embodiments, handle <NUM> is rigidly connected to external tube <NUM>, so that forward movement of button <NUM> pushes forward the inner tube in relation to the outer tube and deploys the deployment element <NUM>.

In some embodiments, when button <NUM> is retained backwards, as shown in <FIG>, inner tube <NUM> does not extend outwardly of the distal end of the outer tube and deployment element <NUM> (not shown) is collapsed and held within external tube <NUM>.

<FIG> is a simplified schematic exploded diagram which shows deployment element <NUM> at its constrained collapsed configuration, in accordance with some embodiments of the invention.

In some embodiments, elastic deformations of deployment element <NUM> occur in between its deployed configuration as shown in <FIG> and its constrained configuration as shown in <FIG>.

In an exemplary embodiment of the invention, distal element <NUM> is optimized in the sense that its critical points are designed to utilize the maximal elastically properties of a shape memory material such as Nitinol, potentially enabling a maximal deployment ratio, with minimal longitudinal dimensions, and maximal deployment force.

Without being bound to theory, the above-mentioned optimization is based on a formula which calculates the maximal strain (epsilon) in between an unconstrained and a constrained geometry having radii of curvature R1 and R2 respectively. Even if the theory is incorrect, this does not preclude some embodiments of the invention from working as described. <MAT> wherein," H" is the height of the strut along its longitudinal (bending) dimension.

Referring again to <FIG> the element <NUM> may be considered in segments A, B, C and D having radii of curvatures: R1a, R1b, R1c, R1d, respectively. The same element is shown in <FIG> in the constrained geometry having radii of curvatures: R2a, R2b, R2c=• , R2d=• , respectively. When calculating critical segments A, B, C & D within the distal element's <NUM> unconstrained geometry as per <FIG> and constrained geometry as per <FIG>, and given heights of Ha, Hb, He & Hd respectively, the use of elastic elements to form the structure of deployable element <NUM> becomes optimal over merely tensioned elements as the critical segments may have an <NUM>% strain. Such a strain is normally considered as the maximal elastic strain of a Nitinol or like shape memory substance.

Optionally, deployable element <NUM> has thin bars <NUM> which have small He and Hd dimensions, relative to the loop's width, that is the Ha & Hb dimensions. In such a case of thin bars the deployment force is determined by the nature of the loop. Moreover, when the loop is made of Nitinol and is designed for elastic deployment having <NUM>%-<NUM>% strains - using the formula specified above - then the loop is able to centerline the guide wire even if it is deployed inside a non-circular (pathological) tissue, such as an artery, with a plaque that renders it non-circular. Without being bound to theory, this phenomena occurs due to the plateau property of the Nitinol which applies substantially the same forces over the range of <NUM>%-<NUM>% strain. The plateau property potentially enables the loop to adapt itself to the shape of a vessel wall independently of the level of the irregular geometry of the wall. A potential advantage is that the guidewire is directed by averaging the lumen's (pathological) geometry.

<FIG> is a simplified schematic diagram which shows how the device directs guide wire <NUM> towards the center occlusion <NUM> which blocks or dramatically reduces the blood flow inside vessel <NUM>, in accordance with an exemplary embodiment of the invention.

As mentioned, in some embodiments, the device tip is made of Nitinol, which is substantially elastically deformed with a relatively constant force, as per the plateau property of Nitinol discussed above. Thus, the device tip boundaries in effect sense and adjust themselves to the vessel pathological morphology, which may be substantially irregular, and thus automatically direct guide wire <NUM> towards the center of the lumen of the vessel <NUM>.

In contrast, a balloon, which centralizes the guide wire by reconstructing the vessel, may not direct the guide wire towards the vessel lumen's true center. Both the centralizing property as described hereinabove, which is independent of the vessel's morphology, and the device's loop like blunt design dramatically reduce the risk of perforating the vessel's wall. The device of the present embodiments also enables the user (e.g., surgeon, interventional cardiologist, interventional radiologist) to apply larger forces to pass guide wire <NUM> through occlusion <NUM>. The vector of the force may be more accurately along the center line as well.

<FIG> are simplified drawings of elements of the microcatheter with an exterior positioned deployment element, in accordance with the claimed invention. <FIG> is an assembled microcatheter <NUM> using the components of <FIG>, in accordance with an exemplary embodiment of the invention.

The microcatheter <NUM> comprises an inner tube <NUM>, an outer tube <NUM>, and a deployment element <NUM>. The axial displacement of inner tube <NUM> relative to outer tube <NUM> deploys deployment element <NUM>.

The inner tube <NUM> comprises a distal tip <NUM>. Optionally, tip <NUM> is shaped for piercing of a lesion (e.g., thrombus, embolus, plaque, atheroma), for example, by being tapered and/or conical. Optionally, tip <NUM> is shaped to be flush against a guidewire extending out through lumen <NUM> (e.g., without a gap between the guidewire and tip <NUM>).

The tip <NUM> forms a flange <NUM> around at least a portion of the exterior circumference of tube <NUM>. Alternatively, flange <NUM> is a separate element from tip <NUM> (e.g., tip is flush with tube <NUM>).

The inner tube <NUM> comprises a lumen <NUM> sized for accepting a guidewire. The caliber of the guidewire is, for example, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or other smaller, intermediate or larger diameters. Optionally, there is more than one lumen, for example, a second lumen for injection of contrast.

The outer tube <NUM> comprises a lumen <NUM> sized for insertion of inner tube <NUM> therein.

An external diameter of outer tube <NUM> forms a flange <NUM> relative to the surface of inner tube <NUM> (e.g., when inner tube <NUM> is inserted in lumen <NUM>).

Axial displacement of inner tube <NUM> relative to outer tube <NUM> increases or decreases the distance between flanges <NUM> and <NUM>. The inner tube <NUM> is moved and outer tube <NUM> remains stationary. Alternatively, outer tube <NUM> is moved and inner tube <NUM> remains stationary. Alternatively, both inner tube <NUM> and outer tube <NUM> are moved.

The inner tube <NUM> and/or outer tube <NUM> are produced from available materials, not necessarily limiting examples include; nylon, polyimide, polyamide, PTFE, metals (e.g., metallic multi helix tubes) and/or combinations of polymers with metallic reinforcement (e.g., polymer made tube having metallic braining wire reinforcement therein, metallic multi-helix tubes having a polymeric coating thereof. Optionally, inner tube <NUM> and/or outer tube <NUM> are coated with a hydrophilic coating (e.g., hydrophilic polysaccharide), for example, to enable low friction of the device against the vessel walls. Potentially, the low friction reduces or prevents trauma to the vessel wall.

The distal portion of inner tube <NUM> and/or outer tube <NUM> are made from a relatively more flexible material than the rest of the catheter, for example, the most distal <NUM>, or <NUM>, or <NUM>, or <NUM>, or other smaller, intermediate or larger sizes. Potentially, the flexible distal tip provides for navigation through tight turns in the blood vessels, for example, as described herein.

A deployment element, for example, helix <NUM> (e.g., one or more helixes can be used) is disposed along the outer surface of inner tube <NUM>, between flange <NUM> and flange <NUM>. Optionally, helix <NUM> comprises reinforced edges <NUM> (e.g., proximal and/or distal) for positioning against flanges <NUM> and/or <NUM>. Optionally, helix <NUM> is flush with the surface of outer tube <NUM> and/or at least some of distal tip <NUM>.

The helix <NUM> is secured to outer tube <NUM> (e.g., at flange <NUM>), for example, by glue, friction, crimping or other methods. The helix <NUM> is not secured to inner tube <NUM>, for example, able to slide over the exterior of tube <NUM>.

A potential advantage of the externally positioned deployment element is freeing up the inner lumens of the tubes. Another potential advantage is that the outer diameter of the microcatheter is not larger with the deployment element than without the deployment element (e.g., when deployment element is not deployed). Potentially, the presence of the helix (or other deployment element on the catheter) does not interfere with passing the microcatheter through the vascular.

<FIG> is an exemplary method of operation using the deployment element at the tip of the microcatheter, in accordance with an exemplary embodiment of the invention. The method is not meant to be necessarily limiting, as some boxes are optional and some boxes can be repeated in different orders. Furthermore, different deployment elements can be used.

At <NUM>, the deployment element is expanded to secure the position of the distal end of the microcatheter in the vessel, in accordance with an exemplary embodiment of the invention. Optionally, the deployment element is expanded by relative motion of the inner and outer tubes, for example, as described with reference to <FIG>-C (e.g., using the handle). Alternatively, the deployment element is expanded by retraction of an outer encasing sheath, for example, as described with reference to <FIG>.

In an exemplary embodiment of the invention, the deployment element is expanded when inside a vessel in near proximity to a lesion, for example, as described with reference to <FIG>.

Optionally, at <NUM>, the guidewire is pushed into the lesion, in accordance with an exemplary embodiment of the invention. In an exemplary embodiment of the invention, the deployment element secures the position of the end of the microcatheter as the guidewire is being pushed into the lesion. Optionally, the guidewire is pushed parallel to the vessel wall, the parallel position provided by the deployment element. Optionally or additionally, the guidewire is pushed into the central part of the lesion, the piercing position provided by the deployment element.

Further details of piercing the lesion with the guidewire are provided, for example, with reference to <FIG>.

Optionally, at <NUM>, the inner tube of the microcatheter is pushed into the lesions, in accordance with an exemplary embodiment of the invention. Optionally, as in <NUM>, the deployment element provides one or more functions during the piercing, for example, stability, centering and/or parallel positioning.

Optionally, the outer tube is retracted before pushing the inner tube, for example, as described with reference to <FIG>.

Further details of piercing the lesion with the inner tube are provided, for example, with reference to <FIG>.

Optionally, at <NUM>, an outer encasing sheath is pushed over the proximal end of the microcatheter towards the distal end. Optionally, the sheath is pushed across tight turns in the vessels. Further details of pushing the sheath over the guidewire are provided, for example, with reference to <FIG>.

At <NUM>, the deployment element is retracted, in accordance with an exemplary embodiment of the invention. Optionally, retraction of the element is performed by relatively motion of the inner and outer tube. Alternatively of additionally, retraction is performed by encasing the deployment element in a sheath.

Optionally, at <NUM>, one or more of <NUM>, <NUM>, <NUM>, <NUM>, <NUM> are repeated.

In some embodiments, <NUM> and <NUM> are repeatable, for example, the deployment element can be expanded and retracted repeatedly.

In some embodiments, the method is used to pierce through a lesion, for example, using <NUM>, <NUM>, optionally using <NUM> and <NUM>. The method can be repeated (<NUM>) to pierce through other lesions.

In some embodiments, the method is used to pass a catheter through tortuous blood vessels, for example, using <NUM>, <NUM>, <NUM> and repeating (<NUM>) as necessary to pass all the tight turns to reach the target tissue.

<FIG> is a diagram of microcatheter <NUM> inside vessel <NUM> having a vessel blocking lesion <NUM> (e.g., thrombus, embolus, plaque). The microcatheter <NUM> has been threaded over a guidewire <NUM>.

The helix <NUM> is located proximally to a distal tip of catheter <NUM>, for example, about <NUM> away, about <NUM> away, about <NUM> away, about <NUM> way, or other smaller, intermediate or larger distances. A potential advantage of the proximal location of the deployment element is that guidewire <NUM> can be positioned close to lesion <NUM>, for example, without interference from the deployment element.

<FIG> is a diagram of microcatheter <NUM> with the deployment element (e.g. helix <NUM>) having been deployed.

The helix <NUM> has been compressed and/or deformed by reducing the axial distance between flange <NUM> of inner tube <NUM> and flange <NUM> of outer tube <NUM>. Helix <NUM> is biased and/or shaped so that reduction in the axial length is translated into expansion and/or an increase in the radial dimension.

The ratio of compression of helix <NUM> in an axial direction to the corresponding expansion in the radial direction is, for example, about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or about <NUM>:<NUM>, or other smaller, intermediate or larger ratios are used.

The microcatheter <NUM> (e.g., deployed helix <NUM>) provides distal support to guidewire <NUM>. Optionally, the support allows for pushing of guidewire <NUM> inside lesion <NUM> (e.g., by an operator from outside the body). Potentially, the risk of guidewire <NUM> moving and perforating the vessel wall is reduced or prevented. Potentially, the risk of guidewire <NUM> inserted into lesion <NUM> at an angle, with a projection towards the vessel wall, is reduced or prevented.

<FIG> is blown up picture of helix <NUM>. The helix <NUM> is made up of a shape memory metal, for example, Nitinol.

One or more radio-opaque markers <NUM> and/or <NUM> are positioned within helix <NUM>. Some not necessarily limiting examples of radio-opaque markers include; gold, tungsten, platinum, (e.g., within struts <NUM>). Optionally, markers <NUM> and/or <NUM> are placed within struts <NUM>, for example, inside a pre-cut hole, for example, by using a laser to melt the front and back edges to a bigger caliber so that the markers are geometrically locked inside the hold. Optionally, markers <NUM> and/or <NUM> are embedded within struts <NUM> at the location which will experience the larger deformation, for example, approximately the middle of struts <NUM>. Potentially, markers <NUM> and/or <NUM> are used to help estimate the radial expansion diameter of helix <NUM>.

The deployed helix <NUM> is sized and/or shaped to approximately center microcatheter <NUM> inside vessel <NUM>, for example, helix <NUM> expands approximately equally around the circumference of microcatheter <NUM>. In an exemplary embodiment of the invention, helix <NUM> expands to a total diameter of about <NUM>, or about <NUM>, or about <NUM>, or about <NUM>, or about <NUM>, or other smaller, intermediate or larger diameters.

In an exemplary embodiment of the invention, helix <NUM> comprises at least one strut <NUM> compressible in an axial direction, for example, <NUM>, <NUM>, <NUM>, or other intermediate or larger numbers of struts are used. Optionally, struts <NUM> are arranged approximately equally spaced apart around the circumference of inner tube <NUM>. Optionally, struts <NUM> have a relatively long pitch, for example, one tip of strut relative to another completes no more than about <NUM> degree (e.g., turn relative to circumferential surface of inner tube <NUM>), or no more than about <NUM> degrees, or <NUM> degrees, or <NUM> degrees (e.g., half a turn), or <NUM> degrees, or <NUM> turn, or <NUM> turns, or <NUM> turns, or other smaller, intermediate or larger number of turns. In an exemplary embodiment of the invention, the axial length of helix <NUM> is, for example, about <NUM>, or about <NUM>, or about <NUM>, or about <NUM>, or about <NUM>, or other smaller, intermediate or larger sizes.

In an exemplary embodiment of the invention, the combination of the long pitch with relatively long axial length allows for precise deployment, for example, relatively long axial movement is transmitted to small amounts of deployment. For example, axial compression of the device by about <NUM>, or about <NUM> or about <NUM>, translates into a radial expansion to a diameter of about <NUM>, or about <NUM>, or about <NUM>, or other combinations of compression and expansion are possible. In an exemplary embodiment of the invention, the control in deployment allows the application of sufficient force by the expansion element to the vessel wall to anchor the microcatheter in placed without damaging the vessel wall.

<FIG> is a simplified diagram of guidewire <NUM> piercing atheroma <NUM> and helix <NUM> in the retracted state, in accordance with an exemplary embodiment of the invention. Optionally, <FIG> follows <FIG> in a possible sequence.

In an exemplary embodiment of the invention, helix <NUM> is retractable back to the predeployment state. Optionally, axially displacing outer tube <NUM> in a proximal direction retracts helix <NUM> from the expanded state (e.g., <FIG>).

<FIG> is a simplified diagram of inner tube <NUM> piercing lesion <NUM>, in accordance with an exemplary embodiment of the invention. Optionally, <FIG> follows <FIG> in a possible sequence.

In an exemplary embodiment of the invention, inner tube <NUM> is axially displaced in a distal direction towards atheroma <NUM>. Tip <NUM> is advanced into atheroma <NUM> and optionally through atheroma <NUM>. Potentially, inner tube <NUM> is advanced through atheroma <NUM>, for example, useful in performing procedures distally to atheroma <NUM>.

A potential advantage of attaching helix <NUM> to outer tube <NUM> but not to inner tube <NUM> is to allow for movement of inner tube <NUM> that is not hindered by helix <NUM>. For example, tube <NUM> is advanced within atheroma <NUM>.

In some embodiments, inner tube <NUM> is advanced through atheroma <NUM> while helix <NUM> is held outside of atheroma <NUM>. Alternatively or additionally, tube <NUM> is advanced through atheroma <NUM> together with helix <NUM> (e.g., at the same time or after tube <NUM>). Potentially, helix <NUM> is used to perform other procedures distal to atheroma <NUM>.

Optionally, helix <NUM> is expanded inside atheroma <NUM>. Potentially, expansion of helix <NUM> expands the lumen through atheroma <NUM>, for example, expanding the vessel lumen to allow adequate blood flow through atheroma <NUM> to prevent ischemia of downstream tissues.

<FIG> is a simplified diagram of a deployment element comprising one or more bars 402A-B, in accordance with some embodiments of the invention. Bars 402A-B are shown in the retracted state. In some embodiments, the bars are arranged circumferentially around the inner tube, for example, approximately equally spaced apart. <FIG> is a simplified diagram of the bars 402A-B of <FIG> in the expanded state. In some embodiments, an axially directed force at the tips of the bars is translated into a radial expansion, for example, the formation of one or more curves in the bars. Potentially, the use of bars achieves the highest ratio of axial compression to radial expansion.

<FIG> is a simplified diagram of a deployment element comprising a braid <NUM>, in accordance with some embodiments of the invention. Braid <NUM> is shown in the retracted state. In some embodiments, braid <NUM> comprises a plurality of wires braided together. In some embodiments, braid <NUM> is a sleeve encircling at least some of the outer circumference of the inner tube of the microcatheter. <FIG> shows braid <NUM> in the expanded state. In some embodiments, an axially directed force at the edges of the braid is translated into a radial expansion. Potentially, the use of braids reduces or prevents trauma to the vessel wall by distributing the applied force over a relatively larger surface area.

Optionally, bars 402A-B and/or braid <NUM> are made out of a memory material, for example, Nitinol.

<FIG>-C are simple diagrams of an optional handle <NUM> for use with the microcatheter having the external deployment element, in accordance with some embodiments of the invention. In some embodiments, handle allows for precise control over the axial distance between the inner and outer tubes, for example, precise to within about, or about <NUM>, or about <NUM>, or about <NUM>, or about <NUM>, or about <NUM>, or other smaller, intermediate or larger dimensions. In some embodiments, control over the axial distance provides control of the radial expansion of the deployment element, for example, according to the ratios as described herein.

In some embodiments, handle <NUM> is connected to an inner tube <NUM> of the microcatheter, for example, handle <NUM> is rigidly attached to inner tube <NUM>. Holding handle <NUM> still maintains the position of inner tube <NUM>.

In some embodiments, a button <NUM> controls the axial displacement of an external tube <NUM>. Optionally, turning button <NUM> urges external tube <NUM> forward or backwards. In some embodiments, the forward force of external tube <NUM> applies an axial force on the deployment element (e.g., against the flange of the inner tube). In some embodiments, turning button <NUM> radially expands and/or deforms the deployment element.

In some embodiments, a user output (e.g., progress indicator <NUM>) visually displays the amount of expansion of the deployment element. For example, the button and the indicator are calibrated so that turning of the button moves a bar, indicating the percent and/or distance of deployment. Other user outputs are possible, for example, an electronic screen and/or audio output (e.g., recorded message).

In some embodiments, axially displacing button <NUM> displaces outer tube <NUM>. Optionally, the displacements are directly corresponding. For example, moving button <NUM> from a standard position (e.g., <FIG>) to an axially retracted position (e.g., <FIG>) axially moves outer tube <NUM> in a proximal axial movement relative to inner tube <NUM>. Optionally, the axial movement of button <NUM> axially displaces the displacement element, for example, as shown with reference to <FIG> (e.g., standard position) and <FIG> (e.g., axially retracted). In some embodiments, button can be moved no more than about <NUM>, or about <NUM>, or about <NUM>, or about <NUM>, or about <NUM>, or other smaller, intermediate or larger distances.

In some embodiments, a second button and/or button <NUM> lock the relative position of outer tube <NUM> and inner tube <NUM>. Optionally or additionally, the position of the guidewire is locked.

Optionally, a luer is assembled on the distal end of the microcatheter (e.g., inner tube <NUM>), for example, to allow injection of fluids such as contrast.

Some potential advantages of the handle include; ability to deploy the element and control the microcatheter using one hand, visual feedback on the deployment, prevention of over-retraction of the outer catheter.

<FIG> are simple diagrams of some distal tips for the inner tube of the microcatheter, in accordance with some embodiments of the invention.

<FIG> shows an inner tube tip having a cone shaped surface <NUM> at the distal tip and an adjoining cone shaped surface <NUM> slightly proximally thereof (e.g., diameters from distal tip; narrow, increasing in diameter, narrowing again). Potentially, the cone shaped surfaces <NUM> and/or <NUM> allow the distal tip of the inner tube to slide in and out of the atheroma.

In some embodiments, the cone shaped surface <NUM> is sufficiently steep to act as a flange to prevent the deployment element (e.g., helix) from sliding off and/or to act as a stop to allow the helix to expand.

In some embodiments, the inner diameter of the lumen of the internal tube <NUM> decreases in near proximity to the tip. The decrease in diameter is, for example, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, or other smaller, intermediate or larger percentages. The length of the decrease is, for example, about <NUM> from the most distal tip, or about <NUM>, or about <NUM>, or other smaller, intermediate or larger lengths. In some embodiments, the decrease in diameter is shaped and/or sized to provide for geometric continuity of the outer tube over the guidewire. Potentially, the continuity helps the outer tube tip slide into the atheroma more easily.

<FIG> is a simple diagram of an angular distal tip <NUM> of the internal tube, in accordance with some embodiments of the invention. The angle of tip <NUM> relative to the long axis of the proximal portion of the internal tube is, for example, about <NUM> degrees, or about <NUM> degrees, or about <NUM> degrees, or other smaller, intermediate or larger angles. Potentially, the angular tip supports directing the guidewire in a curved (e.g., bifurcating) vessel anatomy. Another potential advantage of the angular tip is helping to direct a guide wire into the sub-intima tissue, for example, in a re-entry or re-canalization vascular procedure.

<FIG> is a simplified diagram of a distal tip of the inner tube having one or more helical grooves <NUM>, in accordance with some embodiments of the invention. Potentially, grooves <NUM> allow for a screw-like penetration of the atheroma and/or forward motion inside the atheroma.

Other shapes of distal tips are possible, for example, convex, concave and/or combinations of the shapes described and/or other shapes. The selection of a suitable distal tip depends on, for example, the anatomy of the blood vessel and/or the makeup of the lesion.

In some embodiments, the tips of <FIG> are made from biocompatible materials, not necessarily limiting example include; polymers, metal, silicon (optionally mixed with radio-opaque powder such as tungsten particles).

<FIG> is a method of treating a patient (e.g., human or other mammals) using the microcatheter with deployment element, in accordance with an exemplary embodiment of the invention. The method is not necessarily limited to the devices described herein, as other devices can be used. The method is also not necessarily limited to the boxes described below, as some boxes are optional and other orders of boxes are also possible.

Optionally, at box <NUM>, a patient is selected for treatment with the microcatheter having the deployment device, in accordance with an exemplary embodiment of the invention. The selecting is done, for example, by the treating physician, for example, by the neurointerventional radiologist, interventional cardiologist, or others performing procedures.

In some embodiments, the patient is selected for treatment based on a lesion blocking blood flow through a blood vessel. Not necessarily limiting examples of lesions include; embolus, thrombus, atheroma. In some embodiments, the size of the blood vessel is no more than, for example, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or other smaller, intermediate or larger sizes. Not necessarily limiting examples of blood vessels include; coronary arteries, brain blood vessels. Alternatively or additionally, the patient is selected for treatment using the microcatheter based on tortuous anatomy, in which case the microcatheter is used to traverse the anatomy to reach the target.

Optionally, at box <NUM>, the microcatheter having the deployment device is inserted into the body of the patient, in accordance with an exemplary embodiment of the invention. Optionally, the arterial system is accessed. Alternatively, the venous system is accessed. Some not necessarily limiting examples of access sites include; femoral artery/vein, radial artery, jugular vein.

Optionally, at box <NUM>, the microcatheter with the deployment device is used to traverse tortuous anatomy, (e.g., as found in the blood vessels of the brain), in accordance with an exemplary embodiment of the invention. For example, as described in the section "EXEMPLARY METHODS OF TRAVERSING TORTUOUS VESSELS".

Alternatively or additionally, the microcatheter is used to provide fine movements, for example, when in close proximity to the lesion, for example, as described in the section "EXEMPLARY METHOD OF TRAVERSING A VESSEL".

At box <NUM>, the deployment device is deployed and the guidewire and/or microcatheter tip (e.g., inner tube) is placed in near proximity to the lesion, in accordance with an exemplary embodiment of the invention. For example, as described with reference to <FIG>. For example, no more than about <NUM> away, or <NUM> away, or <NUM> away, or <NUM> away, or <NUM> away, or <NUM> away, or other smaller, intermediate or larger distances. For example, the device as in <FIG> is used. For example, the device as in <FIG> is used.

Optionally, the deployed device positions the guidewire and/or inner microcatheter tube approximately in the center of the vessel. Optionally or additionally, the guidewire and/or microcatheter inner tube are positioned parallel to the long axis of the blood vessel. Optionally or additionally, the force applied against the vessel walls by the deployment device provides anchoring of at least some of the microcatheter (e.g., outer tube). For example, natural movements of the operator do not displace the deployment device in the vessel.

In some embodiments, deployment occurs by applying an axial compression force to the deployment element, for example, by pushing the outer tube with respect to the inner tube. The force radially expands and/or deforms the element to the deployed configuration. Alternatively, in some embodiments, deployment occurs by removal of an outer encasing sheath. Optionally, a device is used to assist with the deployment, for example, the handle as described with reference to <FIG>.

Optionally, at box <NUM>, the lesion is pierced with the guidewire, in accordance with an exemplary embodiment of the invention. For example, as described with reference to <FIG>.

Optionally, at box <NUM>, the microcatheter (e.g., inner tube) is inserted into the lesion. For example, as described with reference to <FIG>. Optionally or additionally, the deployment element is inserted into the lesion and optionally expanded in the lesions, for example, as described with reference to <FIG>.

Optionally, at box <NUM>, one or more ablation techniques are used, in accordance with some embodiments of the invention. Optionally, one or more therapeutics are injected. For example, injection occurs proximal to the lesion, inside the lesion and/or outside the lesion.

One major obstacle is the initial penetration into the occlusion, which may take place through the occlusion's cortex. When using the deployable element, additional ablation techniques may be used through a carefully centered internal lumen to ease the initial, and potentially also the ongoing, penetration into the occlusion.

The ablation technique may be applied using chemical/pharmacological means (e.g. by injecting a proteolytic material), or electrical means, or ultra-sonic means.

<FIG> is a simplified diagram showing the microcatheter injecting one or more therapeutic substances <NUM> in the blood vessel, in accordance with some embodiments of the invention. In some embodiments, the device, when suitably centered, can be used to deliver plaque-directed local pharmacologic treatments, for example, aimed at priming and/or softening the 'proximal fibrous cap' in order to facilitate a wire crossing through the proximal segment of the lesion. Pharmacologic agents that can be delivered and provide for plaque modification include: <NUM>) collagenous matrix degradation agent (i.e. collagenase), <NUM>) microvessel producers (e.g. thrombolytic agents, contrast injection, angiogenic growth factors used as either proteins or gene-based angiogenic promoters such as vascular endothelial growth factors, hypoxia inducing factors, nitrous oxide, angiopoietin, leptin, etc.).

Alternatively, in some embodiments, the microcatheter injects materials for vessel embolization (e.g., liver chemoembolization using particles, coil embolization to seal a GI bleed). In a some embodiments, the force exerted by the deployment device against the blood vessel wall is sufficient to prevent or reduce sliding backwards of the catheter tip during the embolization procedure, for example, due to momentum of the discharged materials. In some embodiments, the deployment device is secured inside the blood vessel so that kick back from release of the materials does not cause inaccurate positioning. Potentially, non-target embolization complications are reduced or prevented.

Alternatively or additionally, other ablation techniques are used, for example, radiofrequency ablation, for example, as described with reference to <FIG>.

Optionally, at <NUM>, feedback about the deployment and/or procedure is obtained.

Optionally, feedback is obtained about the extent of the expansion of the deployment device. Not necessarily limiting examples include; from the visual indicator on the handle (e.g., <FIG>), using fluoroscopy from the radio-opaque markers (e.g., <FIG>).

In some embodiments, the expansion element is used as feedback. Optionally, in such embodiments, the expansion element is made out of a memory metal (e.g., nitinol) and is formed into the helix in the natural and/or unconstrained, and/or expands with a predefined force. Optionally, the expansion element is attached to both inner and outer tubes. Optionally, applying tension to the expansion element compresses the element for the delivery configuration, for example, by proximally pulling the outer tube relative to the inner tube. In some embodiments, once in position, the expansion element is allowed to expand to the predefined configuration (e.g., helix), for example, by releasing the tension. In some embodiments, the amount of expansion of the expansion element relative to the total possible expansion is used as the feedback, for example, by looking at the visual output on the handle, and/or using the ratio of the radial expansion to axial compression ratio.

Optionally, at <NUM>, one or more boxes are repeated, in accordance with some embodiments of the invention. Optionally, one or more of <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and/or <NUM> are repeated, for example, to treat a second (or more) lesion in the blood vessels.

Optionally, one or more boxes are repeated with adjustments. For example, injection of agents to soften the plaque (e.g., as in <NUM>) is performed before insertion of the guidewire into the lesion (e.g., as in <NUM>). For example, if on feedback (e.g., as in <NUM>) the hole through the lesion by the guidewire (e.g., as in <NUM>) is not sufficiently large, the microcatheter can be inserted into the lesion (e.g., as in <NUM>).

<FIG> are views of a deployment device <NUM> shaped for placing a distal tip <NUM> of the microcatheter in near proximity to the lesion, in accordance with an exemplary embodiment of the invention. <FIG> is an isometric view, <FIG> is a face on view and <FIG> is a side view. Optionally distal tip <NUM> comprises an inner tube of the microcatheter. Optionally, the inner tube comprises at least one lumen sized for a guidewire <NUM> to pass therethrough.

In an exemplary embodiment of the invention, device <NUM> comprises of at least one deployment member attached to tip <NUM>, for example, two loops 608A-B, or <NUM> loops, or other intermediate or larger number of loops. Loops 608A-B comprise of at least a segment for positioning against the vessel wall, for example, a curved surface sized and/or shaped to fit against the vessel wall.

In an exemplary embodiment of the invention, a planar surface of loops 608A-B is positioned at an angle towards tip <NUM>. The angle of the plane of loops 608A-B relative to the surface of tip <NUM> is, for example, about <NUM> degrees to about <NUM> degrees, or about <NUM> degrees, or about <NUM> degrees, or about <NUM> degrees, or about <NUM> degrees. Potentially, the angle prevents or reduces interference of loops 608A-B with the plaque and allows positioning of the tip in close proximity to the plaque. In practice, the angle prevents or reduces back movement of tip <NUM>, as back movement is resisted by the angled loops.

In an exemplary embodiment of the invention, loops 608A-B are made out of a memory material, for example, Nitinol. Optionally, loops 608A-B are made out of wires, for example, Nitinol wires.

In an exemplary embodiment of the invention, loops 608A-B are deployed by an outer sheath or external tube, for example, the sheath encasing the tip <NUM> and loops 608A-B is moved proximally relative to the encased loops 608A-B. Optionally or additionally, loops 608A-B are retracted by moving the encasing sheath distally to the position encasing tip <NUM> and loops 608A-B.

In an exemplary embodiment of the invention, nitinol wires 608A-B are attached to the inner tube (e.g., tip <NUM>). Optionally, the inner tube comprises a plurality of lumens, and wires 608A-B are attached inside the lumens, for example, by using an adhesive. Alternatively, wires 608A-B are attached to tip <NUM>, not necessarily limiting examples include; heating the internal tube and melting the tube over the Nitinol wires 608A-B, using a shrinking tube which is assembled over the wires and attaches wires 608A-B once the shrinking tube has been heated and shrunk. A potential advantage of attaching the wires to the tip is that the wires are torqued when the loop is shrunk, for example, as opposed to reacting with bending strains. Without being bound to the theory, bending stresses tend to be non-homogenous in nature, for example, relatively higher and/or concentrated in certain locations, which potentially lead to earlier failure of the structure. In contrast, torque beam and/or struts tend to develop homogenous internal stresses along the structure. The distribution of the external load may allow for the structure to be able to resist higher loads.

In some embodiments, the internal tube (including tip <NUM>) is made out of a relatively flexible material (e.g., compared to metal), for example, polymer.

<FIG> illustrate another embodiment of the deployment device using loops as described with reference to <FIG>, loops 610A-B being angled in a forward direction (e.g., distally and/or towards the lesion). <FIG> is an isometric view, <FIG> is a face on view and <FIG> is a side view.

In some embodiments, the planar surface of loops 610A-B having an angle relative to the surface of guidewire <NUM> ranging from <NUM> to <NUM> degrees, for example, about <NUM> degrees, about <NUM> degrees, about <NUM> degrees, about <NUM> degrees, about <NUM> degrees, or other smaller, intermediate or larger angles.

Potentially, the forward angling loops prevent or reduce forward motion of the microcatheter tip towards the lesion, for example, preventing inadvertent dislodging of the lesion.

Reference is now made to <FIG> which is a simplified schematic diagram illustrating an alternative configuration of the deployment element <NUM>, in accordance with some embodiments of the invention. In the case of <FIG> the deployment element comprises a distal tip made up of a single helical length <NUM>. Operation is the same as for the device of <FIG> and <FIG> illustrates the deployed geometry.

Reference is now made to <FIG> which is a simplified schematic diagram illustrating an alternative configuration of the deployment element <NUM>, in accordance with some embodiments of the invention. In the case of <FIG> the deployment element comprises a distal tip made up of three fins or petals <NUM> which in the deployed state open out into a tripod configuration. Operation is the same as for the device of <FIG> and <FIG> illustrates the deployed geometry.

It is noted that guide wire <NUM> may pass longitudinally through the whole lumen. Alternatively the wire may pass through a side slit through the external tube and into the flexible inner tube, thus enabling the use of a relatively shorter guide wire.

<FIG> are four simplified diagrams that demonstrate a tool according to a some embodiments of the invention, which consists of two flexible tubes, one being assembled over the other, and wherein the tubes enable self-driving of the tool through a blood vessel to clear the blood vessel of plaque during an angioplasty. An external flexible tube <NUM> comprises external deployment element <NUM>. An internal deployment element <NUM> comprises internal deployment element <NUM>.

As shown in <FIG> initially external deploying element <NUM> is opened while afterwards internal flexible tube <NUM> is driven forward, and the distal deploying element <NUM> is deployed (<FIG>). At this point, external or proximal deploying element <NUM> is shrunk into its external tube <NUM>. Then the proximal flexible element is driven forward and deployed at a new forward position immediately behind the forward position reached by the distal deploying element <NUM>, as shown in <FIG>.

Finally distal deployable element <NUM> is shrunk into its internal tube, and the cycle is repeated with the tool advancing forward.

Optionally, the above stages can be repeated over and over to drive the tool longitudinally along the blood vessel. Optionally a proximal handle may be provided to sequentially switch between the above stages automatically.

Optionally, one of the two deploying elements, either the proximal or the distal element, comprises a balloon.

A potential advantage of such a two-deploying-element mechanism is to direct/drive a guidewire through a substantially long occlusion, such as the kinds that are typically encountered in the peripheral vessels and peripheral angioplasty.

Reference is now made to <FIG>, which is a simplified diagram showing a variation of the tool, in accordance with some embodiments. An elongate continuous external tube <NUM> has either a cone-like distal tip <NUM> and/or a screw tip with threads <NUM>. Potentially, the tips enable better accessibility through the blood vessel to approach and subsequently pass through into the occlusion.

<FIG> is a simplified schematic diagram showing a guide wire <NUM> with a deployment element according to the present embodiment and also including an internal electrode <NUM> for treating the cortex using a magnetic or RF field. The deployable elements and the associated elongate body are covered by the electrical isolation of the external tube <NUM>, and the tube and the electrodes are combined with an electrical power source, for example an RF power source. In use, an electrical ablating field is generated in between the deployable element and the guide wire. The electrical field may be confined or substantially confined inside the boundaries of the deployable element, and may be mostly concentrated at the centered guide wire tip.

Reference is now made to <FIG> which is an alternative embodiment of the guide wire of <FIG>. In <FIG>, a double electrode guide wire may be used following centering by the deployable element. In that case the guidewire's electrodes <NUM>, <NUM>, are connected with the electrical power source and the electrical ablation occurs only at the guidewire's distal tip <NUM>. Again the field is confined by the deployment element and is effective in deploying against the cortex at the beginning of the occlusion.

The deployment element may be sold separately from the microcatheter, for example as a kit or a set. Optionally, many different deployment elements are available, for example, different expansion sizes (e.g., for different diameter vessels), different lengths and/or number of contact points (e.g., for irregular vessels).

In one example, the kit comprises: a deployment element at the end of a long wire or catheter for insertion through a lumen into the vasculature, for example, as described with reference to <FIG>, <FIG>, and/or 33A. Optionally, different shapes of the deployment element are available, for example, as described with reference to <FIG>. Optionally or additionally, the deployment element is sold with a handle for expansion and retraction, for example, as described with reference to <FIG> and/or <NUM>. Optionally or additionally, special catheters (having the lumen) having ends with different features are also sold, for example, as described with reference to <FIG>, and/or 14B.

In another example, the kit comprises: different types of deployment elements adapted to be placed around the outer portion of the inner tube, for example, as shown in <FIG>, <FIG>. Optionally or additionally, the kit comprises the inner tube (e.g., <FIG>), optionally different ends are available for the inner tube (e.g., <FIG>_. Optionally or additionally, the kit comprises the outer tube (e.g., <FIG>). Optionally or additionally, the kit comprises the control handle (e.g., <FIG>). EXEMPLARY METHODS OF TRAVERSING TORTUOUS VESSELS - not according to the claimed invention and provided for illustration purposes only <FIG> illustrate a possible sequence of a method of using the microcatheter having the distal deployment device to navigate tortuous vessels (e.g., brain arterial vasculature), in accordance with an exemplary embodiment of the invention. Optionally, the microcatheter is used to help pass an outer catheter (e.g., encasing sheath) through the challenging anatomy. Some not necessarily limiting examples of procedure requiring traversing through challenging anatomy include; interventional neuroradiology procedures, liver vessel embolization, GI bleeding control).

<FIG> is a simplified diagram of vessel anatomy to help understand why passing an outer catheter <NUM> over a guidewire <NUM> is difficult or impossible. Passing catheter <NUM> over a microcatheter positioned over guidewire <NUM> is also difficult or impossible. Note guidewire <NUM> is positioned in a highly curved branch vessel <NUM> off main vessel <NUM>. In practice, the problem is that the user of a flexible and/or floppy microcatheter (e.g., which is capable of passing through the vessel curvature) may not provide sufficient rigidity to allow outer catheter <NUM> to pass over the microcatheter. For example, the microcatheter tends to retract upon sliding outer catheter <NUM> thereon. Alternatively, the use of a microcatheter that is rigid enough to let catheter <NUM> slide over without retracting may be too rigid to pass through the vessel curvature.

<FIG> illustrates the use of the microcatheter to help traverse curved branch vessel <NUM>. For example, using microcatheter <NUM> as described with reference to <FIG>. Microcatheter <NUM> is shown with tip <NUM> of inner tube <NUM> having been threaded over guidewire <NUM> and positioned in branch vessel <NUM>. External tube <NUM> and/or helix <NUM> are in main vessel <NUM>.

Optionally, at least a distal end of inner tube <NUM> is made out of a material sufficiently flexible and/or floppy to navigate tight turns (e.g., branch of vessels <NUM> and <NUM>). For example, the most distal <NUM>, or <NUM>, or <NUM>, or <NUM>, or other smaller, intermediate or longer lengths. Optionally or additionally, at least a distal end of outer tube <NUM> is made of a similar material. Not necessarily limiting examples of materials include; nylon, soft Pbax.

<FIG> illustrates helix <NUM> (e.g., or other deployment device) having been pushed into branch vessel <NUM>. Catheter <NUM> is positioned in main vessel <NUM>.

In some embodiments, <FIG> follows in sequence after <FIG>, that is, first inner tube <NUM> is pushed around the curve into vessel <NUM>, followed by helix <NUM> and outer tube <NUM>. Alternatively, <FIG> does not follow <FIG> (e.g., the process of <FIG> is omitted). For example, tip <NUM> (of the inner tube), helix <NUM> and outer tube <NUM> are all pushed together around the curve and into vessel <NUM>. The ability to skip over the method of <FIG> depends, for example, on the preference of the physician in performing the procedure and/or on the flexibility of the materials used in the microcatheter.

<FIG> illustrates the deployment of the deployment device (e.g., helix <NUM>) inside branch vessel <NUM>. In an exemplary embodiment of the invention, deployed helix <NUM> anchors within branch vessel <NUM>, providing sufficient support to advance catheter <NUM> over outer tube <NUM> and from main vessel <NUM> into branch vessel <NUM>. In some embodiments, some tension is applied to outer tube <NUM> and/or inner tube <NUM>, for example, from outside the body of the patient, for example, by the handle. Potentially, the tension helps to prevent deformation of the microcatheter as sheath <NUM> is passed over.

In an exemplary embodiment of the invention, helix <NUM> has a sufficiently low cross sectional area (when in the expanded state) relative to the blood vessel to prevent significant reduction in blood flow to downstream tissues. For example, helix <NUM> blocks no more than about <NUM>% of blood flow, or about <NUM>% of blood flow, or about <NUM>% of blood flow, or about <NUM>% of blood flow, or other smaller, intermediate or larger flow percentages. Potentially, deploying helix <NUM> does not cause dangerous ischemia to the tissues, for example, to the brain during neuro-radiology procedures. Alternatively, in some embodiments, helix <NUM> has a sufficiently high cross sectional area relative to the blood vessel to significantly reduce blood flow. Potentially, the reduction in blood flow is desirable, for example, in embolization procedures, for example, to prevent escape of the embolization materials to healthy tissues.

Reference is now made to <FIG>, which is a simplified schematic diagram illustrating another technique for use with some embodiments, in which a resilient guide wire <NUM> is positioned inside a curved vessel, such as a blood vessel, near an occlusion. As shown the guide wire follows the maximal curved pathway on the vessel's wall, since the guide wire is intrinsically straight and the resilience attempts to restore the guidewire to its intrinsic straight shape. Thus the distal end of the guidewire tends to try to contact the vessel's wall, with the inherent risk of damaging the epithelium or even perforating the vessel's wall.

Reference is now made to <FIG>, a simplified schematic diagram, in which an alternative micro catheter <NUM> based on a flexible tube is shown, in accordance with some embodiments. Optionally, deployment head <NUM> is located at the distal tip of the micro-catheter <NUM>. As shown in <FIG>, when using flexible tube micro-catheter <NUM>, deployment head <NUM> centers the guidewire. Potentially, reducing the risk of harming or even perforating the vessel wall.

Reference is now made to <FIG>, which is a simplified schematic diagram showing an alternative centering device in which a deployable element <NUM> is opened at an angle relative to an elongate tube <NUM> within blood vessel <NUM>, in accordance with some embodiments. A potential advantage, is that despite the steep angle of the guide wire, using the deployment element, it is still able to approach occlusion <NUM> while centered in the vessel.

For simplicity, the above description relates to the vascular field and to angioplasty and like procedures, including peripheral angioplasty. However the same centering technique may be used in other medical procedures involving threading a device through a tube, for example balloon eustachain tuboplasty, fallopian tuboplasty, etc. and others.

Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

Claim 1:
A microcatheter (<NUM>) for insertion within a vessel comprising:
a first, inner, tube (<NUM>) sized and shaped for surrounding at least a portion of guidewire (<NUM>) and having a first flange (<NUM>) at a distal side thereof;
a second, outer, tube (<NUM>) at least partially disposed around said inner tube (<NUM>), said outer tube (<NUM>) being slidingly associated with said inner tube (<NUM>) and having a second flange (<NUM>) at a distal side thereof, such that axial displacement of inner said tube (<NUM>) relative to said outer tube (<NUM>) increases or decreases the distance between said first and second flanges (<NUM>, <NUM>);
a deployment element (<NUM>) comprising a helix, and disposed along the outer surface of said inner tube (<NUM>), and around at least a portion of an exterior of a distal end of the microcatheter (<NUM>) between said first flange (<NUM>) and said second flange (<NUM>) and including edges for positioning against said flanges, wherein said deployment element (<NUM>) is not secured to said inner tube (<NUM>);
said deployment element (<NUM>) being configured for repeated and reversible expansion and collapsing radially, increase in radial dimension of said deployment element (<NUM>) due to reduction in axial length of said deployment element (<NUM>), said reduction in axial length due to reducing an axial distance between said first and said second flanges (<NUM>, <NUM>), said microcatheter (<NUM>) being arranged to allow forward pushing of said guidewire while said deployment element (<NUM>) is expanded; and
said expanded deployment element (<NUM>) contacts the wall of said vessel so that at least part of said inner tube (<NUM>) and said portion of the distal end of the microcatheter (<NUM>) are radially positioned approximately in the middle of said vessel and
wherein said deployment element (<NUM>) has a cross sectional area in said expanded state that is small enough so as not to block more than <NUM>% of blood flow in said vessel.