NL2020410B1 - Stent delivery system - Google Patents

Abstract

A system (100) for delivering a stent (10) to a predetermined stent position (Xs) in a target vessel (V 1) . The stent (10) is wrapped around an inflatable balloon (20) With a guide channel (21). A guide Wire (31) for entering into the target vessel (V 1) passes through the guide channel (21) for guiding the stent (10) into the target vessel (V 1). An anchor Wire (32) determines an anchor position (Xa) relative to a branching position (Xb) of the target vessel (V 1). An anchor port (42) for guiding the anchor Wire (32) determines the anchor position (Xa) relative to the stent position (Xs). The anchor port (42) is configured to determine an exit direction (D) at Which the anchor Wire (32) exits the anchor port (42) at transvers angle (6) With respect to the guide channel (21).

Description

TECHNICAL FIELD AND BACKGROUND

The present disclosure relates to stent delivery, in particular a system for delivering a stent to an obstruction or lesion in a vessel at or near a branching, e.g. to facilitate percutaneous coronary intervention (PCI) of ostial coronary lesions.

Accurate deployment of stents in ostial lesions needs precision in placement which is often difficult using traditional angiographic imaging. For example, the aorto-ostial orifice edge may appear out of plane to the angiographic orifice. To improve placement, Kern et al. [Catheterization and Cardiovascular Interventions 68:901-906 (2006)] describe the so-called anchor tail wire or Szabo technique for positioning a stent in an ostial stenosis. According to the technique a second (anchor) wire is passed through the last cell or strut of a stent. Using mechanical based placement instead of angiographic based positioning, may improve accuracy. Also, the anchor wire fixation may reduce influence of patient induced movement such as breathing during placement. Unfortunately, the known technique involves stent manipulation which may cause disrupted stent struts and increase the possibility of stent dislodgement.

US 6,682,556 Bl discloses a dilatation catheter having an inflation balloon and a catheter shaft with an inflation channel. A first guidewire channel is disposed along the dilatation catheter and has a distal exit at the distal end of the catheter shaft. A second guidewire channel is disposed along the dilatation catheter and has a distal exit attached along the inflation balloon. Guidewires are slidably disposed within the first and second guidewire channels. An oblique ended expandable stent is disposed about the inflation balloon and used to treat bifurcated and side branched arteries and ostial lesions. In the devices of the prior art, the second guidewire channel extends in the same direction as the first guidewire channel which causes the guidewire to exit the channel also in that direction. Unfortunately, this may not provide optimal placement for various topologies of side branches. For example, medical guide wires have a certain stiffness which can make them difficult to bend.

There is a need for improvement in stent delivery allowing accurate placement for different vessel topologies.

SUMMARY

Aspects of the present disclosure provide a system for delivering a stent to a predetermined stent position in a target vessel at or near a branching position, e.g. where the target vessel branches from a lumen (larger cavity) or second vessel (bifurcation). The system typically comprises an inflatable balloon. A guide channel may traverse through or along with the balloon e.g. along a length of the balloon. The stent typically comprising an extendable frame, e.g. mesh, which can be wrapped around the balloon. The system comprises a guide wire which is intended to be guided into the target vessel. The guide wire can pass through the guide channel for guiding the inflatable balloon with the stent along the guide wire into the target vessel. The system also comprises an anchor wire to determine an anchor position relative to the branching position, e.g. wherein the anchor wire abuts an edge of the branching position at the cavity wall and/or second vessel. The system comprises an anchor port for guiding the anchor wire there through. The exit of the anchor port may determine the anchor position e.g. relative to the stent position. The anchor port is configured to determine an exit direction at which the anchor wire exits the anchor port, e.g. depending on a direction which the exit faces.

Preferably, as described herein, the anchor port is configured to provide the exit direction at an angle which is transverse to a length of the guide channel. For example, the anchor port allows the anchor wire to exit the port at directions with an angle close to ninety degrees (perpendicular) to the guide channel. It will be appreciated that allowing or controlling an exit direction of the anchor wire transverse to the guide channel (which is inline with the target vessel) may allow more precise positioning wherein the anchor wire can abut the lumen wall or second vessel very close to branching point even if the angle is perpendicular and even for very stiff types of anchor wire. For example, if the anchor wire is only allowed to exit the anchor port in a direction parallel or nearly parallel to the guide channel, the anchor wire may need a considerable bending radius to conform with the side channel. This bent piece of anchor wire may cause unpredictable positioning of the stent depending on the force applied to the bent wire which typically has a certain stiffness to provide the anchoring function (otherwise, if the wire, is too floppy this may reduce its anchoring and/or steering capability).

Preferably, the anchor port is rotatable e.g. meaning that the exit direction can be adjusted freely or in a controlled manner. For example, the anchor port can be connected to an anchor port line which may allow remote (mechanical) control over the direction by applying torque to the line. Alternatively, or in addition, the anchor port can be connected with a flexible connection allowing free or partially free reorientation of the exit direction. The anchor port typically comprises a closed loop such as a ring or tube with the anchor wire running there through. The anchor port can be a ring or tube which determines the exit direction. By setting the rotation axis at or near the exit point of the anchor wire, the exit position can be maintained while rotating. By maintaining the anchor near an edge of the stent, the edge can be placed close to the branching. Using an optional sleeve, may provide a means for holding the anchor port, either directly or by wrapping the anchor port line. The sleeve may additionally or alternatively also prevent or delay inflation of a part of the balloon, e.g. by partially wrapping the balloon with the sleeve.

BRIEF DESCRIPTION OF DRAWINGS

These and other features, aspects, and advantages of the apparatus, systems and methods of the present disclosure will become better understood from the following description, appended claims, and accompanying drawing wherein:

FIGs 1A schematically illustrates a stent delivery system inserted in a target vessel near a branching with a second vessel;

FIG IB is similar to FIG 1A except the balloon is inflated to extend the stent and force open the target vessel;

FIGs 2A-2C schematically illustrate embodiments with a ring shaped anchor port;

FIGs 3A-3C schematically illustrate embodiments with a tube shaped anchor port;

DESCRIPTION OF EMBODIMENTS

Terminology used for describing particular embodiments is not intended to be limiting of the invention. As used herein, the singular forms a, an and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term and/or includes any and all combinations of one or more of the associated listed items. It will be understood that the terms comprises and/or comprising specify the presence of stated features but do not preclude the presence or addition of one or more other features. It will be further understood that when a connection between structures or components is described, this connection may be established directly or through intermediate structures or components unless specified otherwise.

The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. In the drawings, the absolute and relative sizes of systems, components, layers, and regions may be exaggerated for clarity.

Embodiments may be described with reference to schematic and/or crosssection illustrations of possibly idealized embodiments and intermediate structures of the invention. In the description and drawings, like numbers refer to like elements throughout. Relative terms as well as derivatives thereof should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the system be constructed or operated in a particular orientation unless stated otherwise.

FIGs 1A and IB schematically illustrate various aspects of a stent delivery system 100. Examples of various anchor ports and their connections are illustrated in FIGs 2A-2C (ring shaped) and FIGs 3A-3C (tube shaped)

Typically, the system 100 comprises an inflatable balloon 20 and a stent 10 with an extendable frame 11 wrapped around the balloon 20. In use, the balloon is inflated which extends the mesh 10 to force open the obstruction. The balloon can then be deflated and retracted leaving the stent to keep the target vessel open. The inflatable balloon 20 may accommodate a guide channel 21, e.g. going through the balloon as shown, or along a side of the balloon (not shown). A guide wire 31 for entering into the target vessel VI can pass through the guide channel 21. This may allow guiding the inflatable balloon 20 with the stent 10 along or with the guide wire 31 into the target vessel VI.

As described herein, the obstruction V0 can be adjacent or near a branching of the target vessel VI, e.g. ostial lesion. For example, the target vessel VI branches from a second vessel V2, as shown in the figures. However, the system can also be applied in other types of branching. For example, the target vessel VI may branch from a larger cavity or lumen (not shown), e.g. at or near an aorto-ostial position. In any case the branching may provide opportunity to use a second guidewire or anchor wire for controlling the stent position relative to the branching position Xb, e.g.

corner edge where the target vessel VI starts to branch. For example, as shown, the anchor wire 32 may enter into the second vessel V2 to determine an anchor position Xa of the anchor wire 32 relative to a branching position Xb of the branching with second vessel V2. Alternatively, the anchor wire may enter or remain in a lumen or cavity from which the target vessel branches to determine the anchor position of the anchor wire relative to that branching position (not shown).

In the embodiment shown, an anchor port 42 guides the anchor wire 32 there through. The anchor port 42 may have its exit at a specific position. This may determine the anchor position Xa relative to the stent position Xs. The anchor port 42 may also determine an exit direction D at which the anchor wire 32 exits the anchor port 42. For example, the direction D is indicated in the figure by the direction of the corresponding dash-dotted arrow.

In some embodiments, the anchor port 42 is configured to provide the exit direction D at an angle Θ which is transverse to a length L of the guide channel 21. For example, the transverse angle Θ may be at least fortyfive degrees, at least sixty degrees, or at least seventy degrees, e.g. up to eighty or even ninety degrees with respect to the length L of the guide channel 21 or target vessel VI. The higher the possible angle, the better may the guidewire abut the branching e.g. with the second vessel V2.

In some embodiments, the anchor port 42 may be rotatable or otherwise adjustable with respect to an exit direction of the anchor wire 32 determined by the anchor port 42. This may allow further adaptability in the adjusting the direction of the anchor wire 32, either in transverse directions or otherwise. In some embodiments, the exit direction D is remotely controllable. In one embodiment, the anchor port 42 is connected to an anchor port line 41. In a further embodiment, the anchor port line 41 can be configured to remotely control reorientation AD of the exit direction of the anchor port 42. For example, the exit direction of the anchor port 42 is controllable by rotating the anchor port line 41 as illustrated in the embodiments of FIG 2 A. For example, the anchor port 42 is rotated by rotating the anchor port line 41 around its length, e.g. using an external torque device. Alternatively, or in combination with the remote control, the anchor port 42 can be connected with a rotatable connection, e.g. a unidirectional or preferably a multi-directional or flexible hinge allowing free or partially free reorientation AD of the exit direction D at a fixed anchor position Xa. This is illustrated e.g. by the connection 43 in the embodiments of FIGs 2B or 2C.

Typically, the anchor port 42 comprises a (closed) loop such as a ring, e.g. illustrated in the embodiments of FIGs 2A-2C, or tube, e.g. illustrated in the embodiments of FIGs 3A-3C. Preferably, the anchor wire 32 runs slidable or freely through the loop so its length with respect to the port can be adjusted. Alternatively, it may be envisaged to fixate the anchor wire 32 to the anchor port or provide an appreciable resistance. In some embodiments, the anchor wire 32 may comprise a stop e.g. local widening, which may prevent the anchor wire 32 from completely slipping out of the anchor port 42. When using a loop as anchor port, the exit direction D is typically transverse or perpendicular to a circumference of the loop, e.g. transverse to the opening or exit surface of the ring or tube, or in line with the length of the tube.

Preferably, the anchor port 42 is configured to maintain the anchor position Xa, e.g. the exit point of the anchor wire 32, while allowing adjustment of the exit direction D. In one embodiment, the anchor port 42 is rotatable around an axis in plane with an exit surface of the anchor port 42. For example, the anchor ring is rotatable around an axis in plane with the ring or the anchor tube is rotatable around an axis in plane with its exit surface or exit point of the anchor wire 32 from the anchor port 42, e.g. an aft of the tube rotates around the exit opening maintaining a position of the opening. By rotating the anchor port around its exit surface, the position of the exit surface can be maintained to provide a fixed anchor port position while allowing rotation e.g. to match an angle of the branching e.g. between the target vessel and the second vessel. For example, the exit surface does not or hardly changes position while rotating, e.g. the exit surface or point where the anchor wire exits the anchor port stays at the same position within a margin of one millimeter or less while rotating.

Alternatively, or in addition to an anchor port being rotatable, it may also provide some freedom for allowing a range of different angles for the anchor wire to exit from the anchor port. This is particularly applicable in case the anchor port is ring shaped, e.g. when the ring is relatively thin compared to a difference between the ring’s inner diameter and the anchor wire’s outer diameter. On the other hand, the ring should be kept as small as possible, e.g. to fit in a catheter. So the anchor ring is preferably thinner than half a millimeter, more preferably less than 0.2 mm or even less than 0.1 mm. For example, in one embodiment, the ring is formed of a (stainless) steel wire with a thickness of 0.08 millimeter.

Preferably, the exit of the anchor port 42 is disposed adjacent the stent 10, e.g. at or near the proximal part lOp of the stent 10, although further separation is possible. For example, the exit is typically positioned within a distance of less than two millimeter, or less than one millimeter from the edge. The closer the anchor position to the edge, the closer the stent may placed directly adjacent the branching position . It may also be envisaged for some cases to extend the anchor port slightly, e.g. less than one millimeter, over the edge of the stent 10. This would result in the stent slightly protruding into the second vessel or lumen if desired.

In some embodiments, the system comprises an anchor sleeve 50. which may be configured for (directly or indirectly) holding the anchor port 42 relative to the stent 10 e.g. for maintaining the anchor position Xa relative to the stent position Xs while inflating the inflatable balloon 20. For example, an anchor port line 41, as described earlier can be wrapped by the anchor sleeve 50. This may provide a reliable connection and optionally allow controlling the anchor port position relative to the stent, e.g. by adjusting a length of the anchor port line 41. Alternatively, the anchor port can be connected elsewhere, though preferably not directly to the stent as explained earlier with reference to the traditional Szabo technique. For example, in some embodiments, as illustrated in FIGs 2B and 3B, the anchor port 42 can be part of the anchor sleeve, e.g. directly connected thereto, or through flexible connection 43, and/or integrated with the sleeve. Alternatively, the anchor port 42 may also be connected to the balloon, as illustrated in FIGs 2C and 3C.

In some embodiments, the system comprises an anchor sleeve 50 wrapped around a part of the inflatable balloon 20. Preferably, the anchor sleeve 50 is configured to at least partly prevent or delay the inflating of the inflatable balloon 20 at the part wrapped by the anchor sleeve 50. For example, the anchor sleeve 50 comprises an elastic material providing an elastic force at least partially counteracting inflation of the inflatable balloon 20 at the wrapped part 20p. In particular, the elastic force may be configured to delay the inflating of the inflatable balloon 20 at the part 20p wrapped by the anchor sleeve 50 compared to another, e.g. distal, part 20d of the inflatable balloon 20 at the other side of the stent 10, not wrapped by the anchor sleeve 50. In an optional synergetic combination, the sleeve can also function to hold the anchor port. For example, as shown, the anchor port line 41 can be wrapped by the anchor sleeve 50 together with the part of the inflatable balloon 20.

For example, in the embodiment shown in FIGs 1A and IB, the anchor sleeve 50 is wrapped around a proximal part 20p of the inflatable balloon 20. On the one hand the sleeve may hold the anchor port 42 relative to a proximal part lOp of the stent 10 for maintaining the anchor position Xa relative to the proximal stent position Xs while inflating the inflatable balloon 20. Furthermore, the sleeve may at least partly preventing the inflating of the inflatable balloon 20 at the proximal part 20p wrapped by the anchor sleeve 50. By covering a part of the balloon to delay deployment of the balloon thereat, the other part (e.g. distal part 20d) may be expanded (slightly) earlier when inflating the balloon. This may prevent the stent 10 from being inadvertently moved away from the anchor wire 32, e.g. further into the target vessel VI, when inflating the balloon. Accordingly, a further improved in placement accuracy and reproducibility may be achieved.

Extending the anchor port 42 e.g. aft of the exit, as a rotatably tube instead of a ring, may further facilitate anchor wire manipulation. For example, an axial direction along the tube length may force a direction at which the anchor wire 32 exits the tube. Examples of tube shaped anchor ports are e.g. illustrated in FIGs 3A-3C. The tube shaped anchor port 42 comprises an inner tube diameter 42D and an inner tube length 42L, wherein the inner tube diameter 42D is typically smaller than twice the inner tube length 42L. In other words, the tube length is greater than the tube radius (=half the tube diameter), e.g. the tube length is more than the tube radius by a factor one-and-half, two, two-and-half, or more. Conversely, the ring shaped anchor ports as illustrated e.g. in FIGs 2A-2C may typically have a ring thickness smaller than the ring radius. Preferably, the anchor port 42, e.g. ring or tube, has an inner diameter less than twice a thickness of the anchor wire 32, preferably less than one and half time the thickness, e.g. between a factor 1 - 1.2 times the wire thickness.

Typically, medical guide wires such as the guide wire and/or anchor wire may have thickness or diameter between a quarter millimeter and two millimeters, more typically between half a millimeter and one-andhalf millimeter. Also typically, the wires can be relatively stiff e.g. making it hard to bend the anchor wire over a small radius. For example, the stiffness of the anchor wire can be quantified by its flexural modulus as explained e.g. by Harrison et al. in J Endovasc Ther. 2011 Dec;186:797-801. (doi: 10.1583/11-3592.1). For example, the relatively stiff anchor wire may have a flexural modulus of at least one Giga Pascal (GPa), typically more than 5 GPa, or more than 10 GPa, e.g. between 20 - 200 GPa.

Although the system is described herein with certain configurations, it may also be embodied as a kit of parts. For example, the kit may include the inflatable balloon 20 with the guide channel 21, the stent 10 (typically wrapped around the balloon), the guide wire 31 (typically through the guide channel 21), the anchor port 42 for guiding and directing the anchor wire 32 and possibly the anchor wire 32 through the anchor port 42. In some embodiments, the kit may also include the anchor sleeve 50 and/or the anchor port line 41, possibly held by the sleeve.

The system 100 as described herein, may be used for delivering a stent 10 to a predetermined stent position in a target vessel VI, e.g. artery. For example, the intended stent position may be predetermined by determining the position and/or extent of an obstruction V0 or lesion to be stented in the target vessel. For example the obstruction V0 may be determined by imaging. Typically the obstruction comprises a local narrowing of the vessel which may be forced open by the stent 10. While the obstruction V0 is shown here on different sides of the target vessel, the obstruction can also be on one side, either on the side of the second vessel V2, opposite thereof, and/or sideways therefrom. Also, the obstruction V0 is shown here distally from the second vessel V2 which is where the system as shown may be best applicable. However, the obstruction may also be proximal to the second vessel V2 in which case the guide wire may be disposed at a distal side of the stent 10. Of course, instead of a second vessel, the system can be applied to any type of branching where there is a nearby edge to abut the anchor wire such as a cavity wall at a corner of the cavity with the target vessel.

For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. For example, while synergetic in combination, the sleeve wrapping the balloon may also provide separate benefit in stent placement irrespective of the specific features such as the orientation of the anchor port or the presence of an anchor port line as described.. In interpreting the appended claims, it should be understood that the word comprising does not exclude the presence of other elements or acts than those listed in a given claim; the word a or an preceding an element does not exclude the presence of a plurality of such elements; any reference signs in the claims do not limit their scope; several means” may be represented by the same or different item(s) or implemented structure or function; any of the disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise. Where one claim refers to another claim, this may indicate synergetic advantage achieved by the combination of their respective features. But the mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot also be used to advantage. The present embodiments may thus include all working combinations of the claims wherein each claim can in principle refer to any preceding claim unless clearly excluded by context.

Claims (15)

CONCLUSIONS A system (100) for placing a stent (10) at a predetermined stent position (Xs) in a destination vessel (VI) adjacent to a branch position (Xb) where the destination vessel (V1) branches off from a lumen or second vessel ( V2) comprising the system (100) - an inflatable balloon (20) with a guide channel (21); - the stent (10) comprising an extendable frame (11) wrapped around the inflatable balloon (20); - a guide wire (31) for entering the destination vessel (VI), the guide wire (31) passing through the guide channel (21) for guiding the inflatable balloon (20) with the stent (10) along the guide wire ( 31) in the destination vessel (V1); - an anchor wire (32) for determining an anchor position (Xa) of the anchor wire (32) relative to the branch position (Xb); and - an anchor port (42) for guiding the anchor wire (32) therethrough and determining the anchor position (Xa) relative to the stent position (Xs), wherein the anchor port (42) is configured to determine an exit direction (D) wherein the anchor wire (32) exits from the anchor port (42), characterized in that the anchor port (42) is configured to provide the exit direction (D) at an angle (Θ) that is transverse to a longitudinal direction ( L) of the guidance channel (21). The system of claim 1, wherein the anchor port (42) is rotatable. The system according to claim 1 or 2, wherein the exit direction (D) can be operated remotely. The system of any preceding claim, wherein the anchor port (42) is connected to an anchor port line (41) configured to remotely control the exit direction (D) of the anchor port (42). The system of any preceding claim, wherein the exit direction (D) of the anchor port (42) is operable by rotating an anchor port line (41) connected to the anchor port (42). The system according to any of the preceding claims, wherein the anchor port (42) is connected to via a flexible connection (43) that allows at least partially free reorientation (AD) of the anchor port (42) and its exit direction (D). The system according to any of the preceding claims, wherein the anchor port (42) comprises a closed loop, the anchor wire (32) passing through the loop, the exit direction (D) being transverse to a circumference of the loop. The system according to any of the preceding claims, wherein the anchor port (42) is configured to maintain an exit point of the guide wire (31) while the exit direction (D) of the guide wire (31) is rotated. The system of any preceding claim, wherein the anchor port (42) is rotatable about an axis through an exit point of the anchor wire (32) from the anchor port (42). The system of any preceding claim, wherein the anchor port (42) comprises a rotatable tube extending from the anchor port (42) at the rear of an exit point of the anchor wire (32), the tube being rotatable about an axis through the exit point. The system of any one of the preceding claims, wherein the anchor port (42) is configured to provide an exit point for the anchor wire (32) immediately adjacent a proximal portion (10p) of the stent (10). The system of any one of the preceding claims comprising an anchor string (50), wherein the anchor sleeve (50) is configured to hold the anchor port (42) relative to the stent (10) for maintaining the anchor position (Xa) relative to the stent position (Xs) while the inflatable balloon (20) is inflated. The system of any preceding claim, wherein anchor port (42) is connected to an anchor port line (41) held by an anchor sleeve (50) wrapped around the anchor port line (41). The system of any preceding claim wherein a portion (20p) of the inflatable balloon (20) is enveloped by a sleeve, the sleeve configured to at least partially prevent or delay inflation of the inflatable balloon (20) at the position of the wrapped portion compared to another portion of the inflatable balloon (20) on the other side of the stent (10). A package of components for building the system according to any one of the preceding claims. 1/3