A microtube guide has a microtube combined with a free-floating and removable core. The microtube is generally hollow with a tube shaft and a distal ring, the tube shaft and the distal ring formed from flexible plastic. The distal ring is conformable to the core and straightenable for insertion into a patient's body, and deploys when the core is withdrawn to form a loop. The core is received by the microtube and is configured to advance into the distal ring to cause a diameter of the distal ring to expand, retract, or straighten. The core comprises a tapered segment that tapers in outer diameter from the diameter of the main core wire to a smaller diameter. A distal end segment of microtubing is frictionally affixed to the tapered segment.

BACKGROUND AND SUMMARY

Guidewires, tiny wires designed to navigate vessels within the body, are used in a vast array of medical procedures. After a guidewire is advanced to its desired treatment site, the guidewire acts as a guide that larger catheters can rapidly follow for advancement to the treatment site.

Often in cardiovascular procedures, multiple different types of guidewires are required to perform the desired task. The guidewires are used to navigate medical devices such as catheters and other medical devices in and out of vascular areas and other body regions. The end location and the specific medical device determines what type of guidewire is best suited for the task. The present transcatheter aortic valve replacement (TAVR) procedure requires the exchange of guidewires 6 to 7 times during the course of the operation. With this new hybrid device, the guidewire exchange during the TAVR procedure can be reduced to two exchanges in most cases. This change in procedure will result in a significant reduction in operating time and some savings in material costs. The reduction in operating time should have a positive safety effect and a substantial cost savings result.

The unique construction of the device according to the present disclosure allows it to act as multiple different types of guidewires all in one device. Most currently-used guidewires are constructed of a solid wire or fixed core or slightly-movable core wrapped with wire. These wires have a set flexural strength (flexural modulus) that may vary in different segments of the wire, but the flexural strength at any one segment of the guidewire cannot be changed or adjusted after manufacture or during use in a patient.

A microtube guide according to the present disclosure is a unique “hybrid” concept that uses a microcatheter as the outer component of the guide and a free and movable central core as the inner component of the guide. The distal end of the microcatheter is closed, not open as in a typical catheter. The design of the distal end may vary as needed for different vascular procedures.

The central core of the microtube guide may be tapered for a portion of its distal end, and by adjusting the depth of core insertion into the microcatheter, the stiffness of that segment of the guide may be adjusted. The depth of core insertion or retraction can also be used to change the configuration of the microcatheter guide.

Because the central core drives the stiffness of the guide, cores can be exchanged for other cores having different stiffness, distal taper, or even core wire shape—all with the same outer tube (microcatheter). The core exchange can even be done during the procedure while the outer component of the guide is in the patient. The guide of the present disclosure thus provides the capability of changing wire support during a procedure without having to exchange the device.

Being able to adjust the depth of the unique core can change the configuration of the microtube guide. The shape of the distal end of the central core can be formed as desired by the thermoset process of the polyimide or other manufacturing processes. Advancing or retracting the core can vary this shape of the distal end. Exchanging the core for a stiff or softer, long taper or short taper, distal end can also change the guide's distal configuration or transport performance of the desired device.

In addition, having the outer surface of the device being a smooth microcatheter construction and not a wire wrapped core (as are most of our present guidewires) is be less traumatic to the human tissues. In use with heart TAVR procedures, this characteristic should help prevent wire perforations of the heart or other cardiac or vascular damage.

In some embodiments, these “hybrid” devices will be constructed of a polyimide (or similar substance) microcatheter with or without braid as an internal component. Unlike currently-used microcatheters, the distal end will not be open to the patient. The size (OD) will vary upon the device application—coronary, peripheral, structural heart, cerebral, etc. The inner core is a PTFE coated stainless steel wire or nitinol in one embodiment.

Adjustment collars of the microtube may be used to hold the core position within the microtube, as discussed herein.

DETAILED DESCRIPTION

FIG. 1depicts a microtube guide100comprising a microtube101combined with a free-floating and removable core102according to the present disclosure. The microtube101is a hollow microcatheter, formed from plastic in one embodiment. A proximal opening107of the microtube101receives the core102, which slides within the microtube101to advance and retract in the direction indicated by directional arrow120.

The microtube101comprises a generally straight main shaft103that is hollow to receive the core102. The microtube101further comprises an expandable distal loop105. The distal loop105is disposed at a distal end106of the microtube101. The distal end106of the microtube is closed in the illustrated embodiment, and not open like typical microcatheters.

The guide further comprises a proximal core end104, which in the illustrated embodiment is a section of microcatheter tubing that is fixed to the core102. The outer diameter of the proximal end is generally the same as the outer diameter of the microtube101. When the guide is initially being fed into a patient's vessels, the core102may be fully advanced within the microtube101, i.e., such that there is not an exposed section of core102as is shown inFIG. 2. The proximal core end104being formed from microcatheter tubing of the same diameter as the microtube101provides a smooth, gap-free (or minimal gap) outer surface of the guide100when the guide is being fed into the patient.

The main shaft103of the microtube101is formed from kink-resistant, thin-walled, semi-rigid plastic tube that is 0.035 inches in outer diameter and 0.028 inches in inner diameter in one embodiment. In other embodiments, the main shaft103is formed with braided steel within the plastic of the guidetube (polyimide braid, for example).

In one embodiment, the distal loop105is slightly larger in cross-sectional diameter than the main shaft103, and formed from kink-resistant, semi-rigid plastic tubing that is the range of 0.045-0.054 inches in outer diameter. A transition portion (not shown) between the main shaft103and the distal loop105transitions the main shaft103to the distal loop105in one embodiment. In this regard, the main shaft103may be fused to the distal loop105at the transition portion.

The distal loop105being larger in diameter than the main shaft103helps to prevent excessive forward advancement of the valve delivery system (not shown) that delivers the replacement valve. In addition, the distal loop105being larger in diameter may simplify forming of the microtube101. In this regard, the main shaft103may be fit within and be frictionally received by the distal loop105prior to fusing of the main shaft103to the distal loop105.

The distal loop105is softer than the main shaft103, and when not acted upon by an external catheter (not shown) or the core102, the distal loop forms a loop as shown. In the illustrated embodiment, the body of the distal loop makes about one and one half loops. An outer diameter of the distal loop in this configuration may be about 3.0 centimeters.

When the core102is advanced such that its tip122(shown in dashed line) enters the distal loop105, the tip122contacts an inner surface123of the distal loop105and causes the diameter of the distal loop105to increase. By advancing or retracting the core102, the size of the distal loop105may be enlarged or decreased. Further, the distal loop105may fully straighten upon advancement of the core102as well.

AlthoughFIG. 1illustrates a distal loop105that extends downwardly from the guide, in other embodiments, the loop may be disposed horizontally to the microtube101, i.e., perpendicular to the microtube101, or otherwise oriented differently.

FIG. 2depicts an enlarged view of an exemplary core102according to an embodiment of the present disclosure. The core102is advanced through the proximal opening107(FIG. 1) of the microtube101.

The core102comprises a main shaft110and a tapered distal end111. The main shaft110and the distal end111are formed from flexible polytetrafluoroethylene (PTFE) coated stainless steel in one embodiment. In this embodiment, the distal end111is smaller in diameter than the main shaft110and tapers from the diameter of the main shaft110to a distal tip112. The distal tip112is received by the proximal opening107(FIG. 1) of the microtube101(FIG. 1) and advances into the distal loop105(FIG. 1) of the microtube101.

As discussed above with respect toFIG. 1, the core102further comprises a proximal core end104that is a section of microcatheter tubing fixed to the main shaft110of the core102. An adjustment section113of the core102is disposed adjacent to the proximal core end104. In the illustrated embodiment, the adjustment section113is shown as textured (e.g., etched). The texture in the adjustment section may help the core102grip the inside of the microtube101(FIG. 1).

FIG. 3depicts the guide100ofFIG. 1, showing an exposed section121of the main shaft110of the core102between the microtube101and the proximal core end104of the guide100. The proximal core end104is fixed to the main shaft110of the core102, and the core102is received by and slides within the microtube101. In a method for operating the guide100, the user (not shown) advances the core102within the microtube101until the core102expands the distal loop105to the desired diameter. When the core102has been advanced as desired, the exposed section121of core102will be a length “L” as indicated inFIG. 3. At this point, a collar130(FIG. 4) of the same length “L” may be placed onto the exposed section121, fitting over the core102between a lower end135of the proximal core end104and the proximal opening107. The collar130serves to fix the core102within the microtube101such that it cannot advance further into the microtube101.

FIG. 4depicts an enlarged view of an exemplary collar130as discussed above with respect toFIG. 3. The collar130comprises a generally semi-cylindrical (“C”-shaped) section of microtubing of a length “L,” with a slit131that is sized so that the collar130can fit over the main shaft110(FIG. 3) of the core102(FIG. 3). The collar130further comprises a proximal collar end132and a distal collar end133. When the collar130is installed on the guide100(FIG. 3), the proximal collar end132is adjacent to and contacts the lower end135(FIG. 3) of the proximal core end104(FIG. 3), and the distal collar end133is adjacent to and contacts the proximal opening107(FIG. 3) of the microtube101(FIG. 3). The collar130may be any of various lengths “L,” which lengths are determined by the lengths desired for the user to get the desired advancement of the core102within the microtube101. Thus multiple collar lengths are available depending on the length desired by the user.

FIG. 5depicts a partial view of the guide100with the collar130installed on the guide100to temporarily fix the length of the core102(shown in dashed line) that is advanced within the microtube101. The collar130has an outer diameter that is generally the same as the microtube101and the proximal core end104of the core120, such that when the collar130is installed, the outer surfaces of the proximal core end104, the collar130, and the microtube101are generally flush.

In an exemplary operation of the guide100, the core102may initially be fully advanced into the microtube101such that the microtube101is generally straight, with no looped distal end. In this configuration, the lower end135of the proximal core end104is adjacent to and contacts the proximal opening107of the microtube101. Two users (not shown) may be required to hold the guide100during installation and use due to the length of the guide100. One user typically holds the proximal core end104of the core102while the other user maneuvers the distal end of the guide100into the patient. When the guide102is used in a TAVR procedure, for example, after the distal end of the microtube101crosses the valve, the person holding the proximal core end104may hold it steady while the other person advances the microtube101slightly to deploy the distal end105into a loop as discussed herein. When the distal end105is deployed as desired, a collar130of the desired length “L” can be installed in the now-exposed space between the lower end135of the proximal core end104and the proximal opening107of the microtube101.

In other embodiments, the microtube (not shown) may not have a distal ring. Rather, the microtube may conform to a shape and stiffness of a core (not shown) that has some other shape.

FIG. 6depicts an alternative embodiment of a microtube guide600according to the present disclosure. The microtube guide600comprises a microtube601combined with a free-floating and removable core602. The microtube601is a hollow microcatheter, formed from plastic in one embodiment. Further, in one embodiment, the outer diameter of the microtube601is substantially 0.035 inches and the inner diameter of the microtube601is 0.028 inches.

A proximal opening607of the microtube601receives the core602, which slides within the microtube601to advance and retract in the direction indicated by directional arrow620. In one embodiment, the core602has an outer diameter of 0.026 inches, slightly smaller than the inner diameter of the microtube601, a difference of 0.002 inches from the I.D. of the microtube601.

The microtube601comprises a generally straight main shaft603that is hollow to receive the core602. The dashed line within the microtube601represents the core602sliding within the microtube601.

The microtube601further comprises an expandable distal loop605. The distal loop605is disposed near a distal end608of the microtube601. Although the distal loop605is shown as a loop inFIG. 6, in use on a patient, the distal loop605may be looped as shown or substantially straight, as further discussed herein. The distal end608of the microtube is closed in the illustrated embodiment, and not open like typical microcatheters.

The guide600further comprises a proximal core end604, which in the illustrated embodiment is a section of microcatheter tubing that is fixed to the core602. The outer diameter of the proximal end604is generally the same as the outer diameter of the microtube601. When the guide is initially being fed into a patient's vessels, the core602may be fully advanced within the microtube601, i.e., such that there is not an exposed section of core602as is shown inFIG. 6. The proximal core end604being formed from microcatheter tubing of the same diameter as the microtube601provides a smooth, gap-free outer surface of the guide600when the guide is being fed into the patient.

The microtubing in the area of the distal loop605is softer than that of the main shaft603, and when not acted upon by an external catheter (not shown) or the core602, the distal loop forms a loop as shown. In the illustrated embodiment, the body of the distal loop605makes about one and one half loops, or approximately 540 degrees. An outer diameter of the distal loop in this configuration may be about 3.0 centimeters.

When the core602is advanced such that its tip622(shown in dashed line) enters the distal loop605, the tip622contacts an inner surface (not shown) of the distal loop605and causes the diameter of the distal loop605to increase. By advancing or retracting the core602, the size of the distal loop605may be enlarged or decreased. Further, the distal loop605may fully straighten upon advancement of the core602as well.

The distal end of the microcatheter is set in at least a 360 degree loop. The diameter of the distal loop is determined by the procedure it is designed for. The distal loop for TAVR will be in the range of 2 to 3 cm in diameter.

A distal tip606is disposed at the distal end608of the microtube601. The distal tip606is not hollow like the microtube601, but rather is solid, with no central lumen. The distal tip606of the microcatheter's loop605is softer than the microtube601to be atraumatic and more flexible. The distal tip606is between 1.0 cm and 1.5 cm long in one embodiment.

In one embodiment, the microtube601is a thermoset polymer that retains its shape and recoil even through multiple tasks and prolonged exposure to body temperature. The device of the illustrated embodiment is constructed of polyimide that is reinforced with a stainless steel braid. The stainless steel braid helps prevent the microcatheter from kinking in tortuous vascular areas. In one embodiment, the polyimide is impregnated with PTFE granules to create a low coefficient of friction.

FIG. 7depicts an exemplary embodiment of the core602ofFIG. 6removed from the microtube601. The unique core602controls the performance and shape of the microcatheter600(FIG. 6). The core602can change the configuration of the distal end of the microcatheter600from the full loop to a slight curve to substantially straight. The shape control is determined by adjusting the depth of the core602in the distal loop605(FIG. 6), as further discussed herein.

The main shaft704of the core602comprises PTFE-coated stainless steel wire 0.026″ in outer diameter, in one embodiment. A tapered segment703of the core602is disposed near a distal end708of the core602. The tapered segment703extends between the main shaft704and the distal end portion706, and is shown in further detail inFIG. 7A. The tapered segment703is tapered specifically for control of the microcatheter. The tapering allows that area of the guide to be more flexible, by allowing controlled expansion of the distal loop (and support), without completely straightening it.

The distal end segment706of the core602is disposed at the distal end708of the core602. The distal end segment706comprises polyimide with stainless steel braid microcatheter (0.026″ outside diameter). In this regard, the very distal end of the core consists of a short segment of microcatheter over the stainless steel wire's tip e.g., slid over the tapered portion703and held in place frictionally, in one embodiment.

The distal end segment706of the core602is constructed of the same material as the larger, outer microcatheter itself, but with an outer diameter just less the inner diameter of the outer microcatheter. The outer diameter of the distal end segment706is substantially uniform along its length. The configuration of the distal end segment706allows a gradual transition of the inner core wire's force on the outer microcatheter to prevent a kinking point in the outer microcatheter.

The distal end segment706also provides a contact area with very low friction for interaction of the microtube601(FIG. 6) with the core602. The low friction is a result of the distal end portion706being formed from the same material as the microtube, which is polyimide with PTFE granules in one embodiment.

On a proximal end701of the core wire is fixed a segment of microcatheter that is substantially identical to the body of the microcatheter. This segment of microcatheter serves as a control handle for setting the depth of the core wire within the outer microcatheter, as further discussed herein.

FIG. 7Ais an enlarged partial view of the core602ofFIG. 7, taken along detail line A ofFIG. 7. The tapered segment703tapers from about 0.026 in outer diameter at its proximal end711to about 0.013 inches in outer diameter at its distal end712, over a distance of about 2.5 cm, in one embodiment.

The distal end segment706is frictionally fit over the tapered segment703in the illustrated embodiment. In this regard, the inner diameter of the distal end segment706is only slightly larger than the outer diameter of the distal end712of the tapered segment703. In one embodiment, the inner diameter of the distal end segment706is 0.018″ and its outer diameter is 0.026″. The distal end segment706can therefore slide over the tapered segment703(which has an O.D. of 0.013 inches at its distal end) until it stops. As shown inFIG. 7A, there is an overlap portion713of the core602where the distal end712of the tapered segment703is within the distal end segment706, shown in dashed lines in the figure. In one embodiment, the distal end segment706is about 1 cm long.

The taper of the tapered segment703results in less rigidity of the core602at the distal end of the core. Without the gradual tapering of the tapered segment, the distal end of the core may be stiff enough that it could fold over the microcatheter. The distal end segment706at the very distal end of the core602helps to transition the stiffness on the distal end. With this configuration, if the microcatheter is pushed against a wall, it should not fold over and kink on itself. The result is that the distal loop605(FIG. 6) gradually and uniformly expands and contracts.

In one embodiment, the tapering of the tapered segment703is formed by grinding, such that the main shaft704of the ore and the tapered segment703are unitary. Further, in one embodiment the distal end of the tapered segment703does not have a PTFE coating and is thus not slick, thus allowing it to frictionally adhere to the distal end segment706. In other embodiments, adhesives may be used to adhere the distal end segment706to the tapered segment703.

FIG. 8depicts a prior art method of performing a transcatheter aortic valve replacement. In step801, a user places closures (such as Proglide closures), sheath, J wire, and right Judkins catheter into the femoral artery and aorta of a patient. In step802, the user exchanges the J wire for a Lunderquist wire and places the valve delivery sheath into the aorta.

In step803, the user places an AL-1 catheter over the Lunderquist wire, and advances the AL-1 catheter over the aortic arch using a J wire. In step804, the user exchanges the J wire for a straight tip wire for crossing the aortic valve with an AL-1 catheter.

In step805, the user exchanges the straight tip wire for a long J wire and removes the AL-1 catheter. In step806, the user advances the pigtail catheter over the long J wire into the left ventricle. In step807, the user exchanges the long J wire through the pigtail catheter for a valve delivery wire and removes the pigtail catheter.

In step808, the user positions the transcatheter aortic valve into the area of the aortic valve annulus and deploys the valve. In step809, the user exchanges the valve delivery wire for a J wire for vascular closure. The valve delivery wire is a relatively large stiff wire and vascular closure cannot be performed over such a wire.

FIG. 9depicts a method of performing a transcatheter aortic valve replacement using the device disclosed herein, according to an exemplary embodiment of the present disclosure. In step901of the exemplary method, the user places vascular closures (such as Proglide closures), sheath, J wire, and right coronary catheter into the femoral artery and aorta.

In step902of the method, the user exchanges the J wire through the right catheter for a microcatheter wire in its straight or slightly curved distal tip configuration, and removes the right catheter.

In step903of the method, the user advances the valve delivery sheath over the microcatheter wire into the patient's aorta. In step904of the method, the user places an AL-1 catheter over the microcatheter wire and advances it to just above the aortic valve. In step905of the method, the user then taps the microcatheter wire against the aortic valve until the wire crosses the valve into the left ventricle.

In step906, the user holds the proximal end of the microcatheter core stationary and advances the microcatheter into the patient's ventricle, allowing the distal end of the microcatheter to become circular as it enters the ventricle.

In step907, the user removes the AL-1 catheter over the microcatheter wire. In step908, the user advances the transcatheter valve delivery system over the microcatheter wire and into position in the aortic valve annulus. In step909, the user deploys the valve and the removes the valve delivery system over the microcatheter wire.

In step910, the user performs standard vascular closure with the microcatheter wire. With the device according to the present disclosure, the user can close over the microcatheter/valve delivery wire, by causing the microcatheter wire to become substantially straight. Being able to close over the microcatheter wire results in one less wire exchange in the closure operation.

Further the method900results in several fewer wire exchanges than the method800ofFIG. 8.

The terms “first,” “second,” and the like are used herein to describe various features or elements, but these features or elements should not be limited by these terms. These terms are used only to distinguish one feature or element from another feature or element. Thus, a first feature or element discussed below could be termed a second feature or element, and similarly, a second feature or element discussed below could be termed a first feature or element without departing from the teachings of the present disclosure. Further, the presence of a “first” or “second” feature or element (or the like) does not imply the presence of any additional such feature or element.

This disclosure may be provided in other specific forms and embodiments without departing from the essential characteristics as described herein. The embodiments described are to be considered in all aspects as illustrative only and not restrictive in any manner.