WO2019074815A1

WO2019074815A1 - Force-distributing anchor system

Info

Publication number: WO2019074815A1
Application number: PCT/US2018/054801
Authority: WO
Inventors: Idan Tobis
Original assignee: 4Tech Inc.
Priority date: 2017-10-10
Filing date: 2018-10-08
Publication date: 2019-04-18

Abstract

A tension system (10) includes first, second, and third tissue anchors (20A, 20B, 20C) configured to be anchored to first, second, and third sites in a patient's body, respectively. The first tissue anchor (20A) is coupled to the third tissue anchor (20C) via a first superelastic force modulator (30A), and the second tissue anchor (20B) is coupled to the third tissue anchor (20C) via a second superelastic force modulator (30B). The first and the second superelastic force modulators (30A, 30B) are configured, in response to a force being applied to the third tissue anchor (20C) by tissue at the third site, to distribute the force in a predetermined ratio between the first and the second tissue anchors (20A, 20B), when the first, the second, and the third tissue anchors (20A, 20B, 20C) are anchored to the first, the second, and the third sites, respectively. Other embodiments are also described.

Description

FORCE-DISTRIBUTING ANCHOR SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from US Provisional Application 62/570,226, filed October 10, 2017, which is assigned to the assignee of the present application and is incorporated herein by reference.

FIELD OF THE APPLICATION

The present invention relates generally to tissue anchors, and specifically to tissue anchors for implantation at cardiac sites.

BACKGROUND OF THE APPLICATION

Tissue anchors are used for anchoring elements, such as pacemaker electrode leads or sutures, to tissue, such as bone or soft tissue. PCT Publication WO 2015/063580 to Gilmore et al, which is incorporated in its entirety herein by reference, describes a valve- tensioning implant that includes a first venous tissue anchor, which is configured to be implanted in a vein selected from the group of veins consisting of: a superior vena cava, an inferior vena cava, and a coronary sinus; exactly two atrial tissue anchors, which consist of second and third atrial tissue anchors; and a pulley system. The pulley system includes a pulley, which is connected to the second atrial tissue anchor; and a tether, which (a) is connected to the first venous tissue anchor and the third atrial tissue anchor, (b) is moveable through the pulley, and (c) has a length, measured between the first venous and the third atrial tissue anchors, of at least 30 mm.

US Patent 8,377,079 to Coe et al. describes methods and devices for regulating a restriction system. A restriction system is provided having a restriction device coupled to a port with a fluid disposed in the device, such that the restriction device is adapted to form a restriction in a pathway corresponding to an amount of fluid contained in the device, and a pressure adjustment unit in communication with the port and effective to maintain a substantially constant equilibrium pressure between the pressure adjustment unit and the restriction device. The pressure adjustment unit is configured to regulate an amount of fluid in the restriction device in response to a fluid pressure acting on the device. In one configuration, a constant force mechanism is provided is in the form of a nitinol spring that applies a constant force to a transfer mechanism. SUMMARY OF THE APPLICATION

Applications of the present invention provide a tension system for applying and distributing tension between first, second, and third sites in a patient's body. The tension system comprises first, second, and third tissue anchors configured to be anchored to the first, the second, and the third sites, respectively; and first and second superelastic force modulators. The first tissue anchor is coupled to the third tissue anchor via the first superelastic force modulator, and the second tissue anchor is coupled to the third tissue anchor via the second superelastic force modulator. The first and the second superelastic force modulators are configured, in response to a force being applied to the third tissue anchor by tissue at the third site, to distribute the force in a predetermined ratio between the first and the second tissue anchors, when the first, the second, and the third tissue anchors are anchored to the first, the second, and the third sites, respectively.

There is therefore provided, in accordance with an application of the present invention, a tension system for applying and distributing tension between first, second, and third sites in a patient's body, the tension system including:

first, second, and third tissue anchors configured to be anchored to the first, the second, and the third sites, respectively; and

first and second superelastic force modulators,

wherein the first tissue anchor is coupled to the third tissue anchor via the first superelastic force modulator, and the second tissue anchor is coupled to the third tissue anchor via the second superelastic force modulator, and

wherein the first and the second superelastic force modulators are configured, in response to a force being applied to the third tissue anchor by tissue at the third site, to distribute the force in a predetermined ratio between the first and the second tissue anchors, when the first, the second, and the third tissue anchors are anchored to the first, the second, and the third sites, respectively.

For some applications, the first and the second superelastic force modulators are configured to distribute the force equally between the first and the second tissue anchors. Alternatively, the first and the second superelastic force modulators are configured to distribute the force non-equally between the first and the second tissue anchors. For some applications, the first and the second superelastic force modulators include respective superelastic wires including respective non-straight portions. For some applications, the non-straight portions are coiled. Alternatively or additionally, for some applications, the non-straight portions are curved, such as sinusoidal. Alternatively, for some applications, the non-straight portions are zigzagged.

For any of the applications described above, the tension system may further include one or more tethers that couple the first tissue anchor to the third tissue anchor via the first superelastic force modulator, and the second tissue anchor to the third tissue anchor via the second superelastic force modulator. For some applications, the first and the second superelastic force modulators are coupled to each other via exactly one tether.

There is further provided, in accordance with an application of the present invention, a method for applying and distributing tension between first, second, and third sites in a patient's body, the method including:

anchoring first, second, and third tissue anchors of a tension system to the first, the second, and the third sites, respectively, wherein the first tissue anchor is coupled to the third tissue anchor via a first superelastic force modulator, and the second tissue anchor is coupled to the third tissue anchor via a second superelastic force modulator; and

moving the first, the second, and the third sites closer together by applying tension between the first, the second, and the third tissue anchors, such that the first and the second superelastic force modulators, in response to a force being applied to the third tissue anchor by tissue at the third site, distribute the force in a predetermined ratio between the first and the second tissue anchors.

For some applications, applying the tension includes applying the tension between the first, the second, and the third tissue anchors via one or more tethers that couple the first tissue anchor to the third tissue anchor via the first superelastic force modulator, and the second tissue anchor to the third tissue anchor via the second superelastic force modulator. For some applications, the first and the second superelastic force modulators are coupled to each other via exactly one tether.

For any of the applications described above, moving the first, the second, and the third sites closer together may include reducing a size of an atrioventricular valve orifice, such as the tricuspid valve orifice. For some applications, the first and the second sites are in a vicinity of the tricuspid valve, and the third site is in a vein selected from the group of veins consisting of: a superior vena cava, an inferior vena cava, and a coronary sinus.

The present invention will be more fully understood from the following detailed description of embodiments thereof, taken together with the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Figs. 1A-B are schematic illustrations of respective configurations of a tension system for applying and distributing tension between first, second, and third sites in a patient's body, in accordance with respective applications of the present invention;

Fig. 2 is a graph illustrating an exemplary stress-strain curve for a nitinol spring; and

Fig. 3 is a schematic illustration of the tension system of Fig. 1A applied to a tricuspid valve, in accordance with an application of the present invention.

DETAILED DESCRIPTION OF APPLICATIONS

Figs. 1A-B are schematic illustrations of a tension system 10 for applying and distributing tension between first, second, and third sites in a patient's body, in accordance with respective applications of the present invention. Tension system 10 comprises a first tissue anchor 20 A, a second tissue anchor 20B, and a third tissue anchor 20C configured to be anchored to the first, the second, and the third sites, respectively. For some applications, one or both of first and second tissue anchors 20A and 20B are configured to be anchored by penetrating tissue. Alternatively or additionally, for some applications, third tissue anchor 20C comprises a stent 44. For example, stent 44 may implement techniques described in above-mentioned PCT Publication WO 2015/063580 to Gilmore et al. and/or in PCT Publication WO 2014/141239 to Tobis et al, which is incorporated herein by reference, or in any of the other patent applications incorporated hereinbelow by reference. Alternatively, third tissue anchor 20C is configured to penetrate tissue, and may comprise one of the tissue anchors described herein with reference to Figs. 1A-B regarding first and second tissue anchors 20A and 20B.

Tension system 10 further comprises first and second superelastic force modulators 30A and 30B. First tissue anchor 20A is coupled to third tissue anchor 20C via first superelastic force modulator 3 OA, and second tissue anchor 20B is coupled to third tissue anchor 20C via second superelastic force modulator 30B. First and second superelastic force modulators 30A and 30B comprise a superelastic material, such as nitinol.

First and second superelastic force modulators 30A and 30B are configured, in response to a force being applied to third tissue anchor 20C by tissue at the third site, to distribute the force in a predetermined ratio between first and second tissue anchors 20A and 20B, when first, second, and third tissue anchors 20A, 20B, and 20C are anchored to the first, the second, and the third sites, respectively.

For some applications, first and second superelastic force modulators 30A and

30B are configured to distribute the force applied to third tissue anchor 20C equally between first and second tissue anchors 20A and 20B. For example, first and second superelastic force modulators 30A and 30B may be configured to have the same stress- strain curve. Because of this equal force distribution, first and second tissue anchors 20A and 20B each apply half of the force to their respective tissue implantation sites that would be applied if only a single tissue anchor were provided in place of first and second tissue anchors 20A and 20B. Furthermore, in the absence of first and second superelastic force modulators 30A and 30B, even if first and second tissue anchors 20A and 20B were still provided, generally only one of first and second tissue anchors 20A and 20B would bear most of the force applied by third tissue anchor 20C (unless pulley 400 is provided, as described hereinbelow).

In addition, for some applications, such as shown in the figures, first and second tissue anchors 20A and 20B are tissue-penetrating anchors that are implanted around the annulus of the right atrium using mechanical purchase, and third tissue anchor 20C comprises an intraluminal stent that is configured to be implanted in the superior vena cava, the inferior vena cava, or the coronary sinus and provide anchorage using friction only. Tension system 10 is arranged to apply relatively less force on the stent anchor than on one or both of the other tissue-penetrating anchors.

Still further, first and second superelastic force modulators 30A and 30B may serve to maintain the same force applied to the tissue at the first and second sites during the entire systolic cycle. Also, first and second superelastic force modulators 30A and 30B may serve to set a maximum force applied to the tissue at the first and second sites to a fixed value (e.g., 8 N), based on the stress-strain curves of first and second superelastic force modulators 30A and 30B.

Alternatively, first and second superelastic force modulators 30A and 30B are configured to distribute the force applied to third tissue anchor 20C non-equally between first and second tissue anchors 20A and 20B. For example, first and second superelastic force modulators 30A and 30B may be configured to have different stress-strain curves. For example, this configuration may be beneficial if one of first and second tissue anchors 20A and 20B is to be implanted in a region of tissue which is thicker or stronger than the site at which the other of first and second tissue anchors 20A and 20B is to be implanted.

For some applications, first and second superelastic force modulators 30A and

30B comprise respective first and second superelastic wires 40A and 40B, e.g., comprising as nitinol, which include respective first and second non-straight portions 42A and 42B. For some applications, non-straight portions 42A and 42B are coiled, such as shown in the figures. For other applications, non-straight portions 42A and 42B are curved, such as sinusoidal, or are zigzagged.

First and second superelastic force modulators 30A and 30B (e.g., first and second superelastic wires 40A and 40B) are configured to apply substantially constant forces to first and second tissue anchors 20A and 20B, respectively, when the force applied to the force modulators falls in a range of forces appropriate for applying tension between the tissue anchors. First and second superelastic force modulators 30A and 30B apply these constant forces because of the properties of the superelastic material of the modulators, e.g., nitinol. The stress-strain curves of first and second superelastic force modulators 30A and 30B include a stress plateau region such that the forces applied by the force modulators remain constant so long as the lengths (i.e., the strains) of first and second superelastic wires 40A and 40B remain within the stress plateau region, i.e., so long as the first and second superelastic force modulators 30A and 30B, during implantation or the application of tension, are not excessively stretched from their original, resting lengths.

For example, Fig. 2 illustrates an exemplary stress-strain curve 46 for a single nitinol spring, as is known in the art. As can be see, the curve includes an upper loading plateau 48A and a lower unloading plateau 48B.

In the inventive arrangement of first and second superelastic force modulators 30A and 30B in the present invention, the upper loading plateau 48A shown on the graph of Fig. 2 determines the force applied to the first and second tissue anchors 20A and 20B during initial tensioning of tension system 10. The lower unloading plateau 48B shown on the graph determines the force applied to first and second tissue anchors 20A and 20B during variations in the applied tension caused by the cardiac cycle. First and second superelastic force modulators 30A and 30B are configured to apply the desired forces to first and second tissue anchors 20A and 20B based on the lower unloading plateau 48B, because the initially applied tension will generally be released during the cardiac cycle. (As is known in the superelastic art, upon a partial release of the initially applied tension, the stress-strain curve of a superelastic spring shifts from the upper loading stress-strain curve to the lower unloading stress-strain curve, and remains on the lower unloading stress-strain curve.)

Typically, tension system 10 further comprises one or more tethers 50 that couple first tissue anchor 20A to third tissue anchor 20C via first superelastic force modulator 30A, and second tissue anchor 20B to third tissue anchor 20C via second superelastic force modulator 30B. For example, tethers 50 may include (a) a first tether 50A (e.g., exactly one first tether 50A) that couples first tissue anchor 20A to second tissue anchor 20B, and (b) a second tether 50B that couples first tether 50A to third tissue anchor 20C. Optionally, first tether 50A is coupled to second tether 50B by a pulley 400, such as described hereinbelow with reference to Figs. 1A-B and 2. Other arrangements of the one or more tethers 50 will be readily apparent to those of ordinary skill in the art who have read the present application, and are within the scope of the present invention. The one or more tethers 50 comprise respective elongate flexible elements, such as cords, sutures, or bands. The tethers are typically sufficiently flexible for twisting or bending but are inelastic against tension. Typically, the one or more tethers 50 have a high tensile strength, in order to enable the tethers to apply tension, as described herein.

Reference is made to Fig. 1A. For some applications, such as shown in Fig. 1A, tension system 10 comprises a tension system 110, and first and second tissue anchors 20A and 20B comprise respective first and second tissue anchors 120A and 120B, which comprise respective helical tissue-coupling elements 122A and 122B. For example, helical tissue-coupling elements 122 A and 122B may implement techniques described in above-mentioned PCT Publication WO 2015/063580 and/or PCT Publication WO 2015/193728 to Gilmore et al, which is incorporated herein by reference, or in any of the other patent applications incorporated hereinbelow by reference. Reference is made to Fig. IB. For other applications, such as shown in Fig. IB, tension system 10 comprises a tension system 210, and first and second tissue anchors 20A and 20B comprise respective first and second tissue anchors 220A and 220B. First and second tissue anchors 220A and 220B comprise respective elongate tissue-coupling portions 224A and 224B, and, optionally, respective flexible elongate tension members 226A and 226B, which are coupled to respective portions of tissue-coupling portions 224A and 224B. For example, first and second tissue anchors 220A and 220B may implement techniques described in PCT Publication WO 2016/087934 to Gilmore et al, PCT Publication WO 2016/189391 to Gilmore et al, PCT Application PCT/US 17/047442, filed August 17, 2017, and/or US Provisional Application 62/516,894, filed June 8, 2017, all of which assigned to the assignee of the present application and are incorporated herein by reference, or in any of the other patent applications incorporated hereinbelow by reference.

Alternatively, one or both of first and second tissue anchors 20A and 20B are not configured to penetrate tissue, and may comprise, for example, respective stents.

Reference is now made to Fig. 3, which is a schematic illustration of tension system 110, described hereinabove with reference to Fig. 1A, applied to a tricuspid valve 300 in a right atrium 302, in accordance with an application of the present invention. Tension system 210, described hereinabove with reference to Fig. IB, may be applied to tricuspid valve 300 in the same manner, mutatis mutandis. In this exemplary implantation, a first site 31 OA at which first tissue anchor 20A is anchored is an anteroposterior commissure 312, a second site 310B at which second tissue anchor 20B is anchored is a circumferential middle 314 of a septal leaflet 316, and a third site 3 IOC at which third tissue anchor 20C is anchored is an inferior vena cava 318. The tissue anchors may also be implanted, for example, at any of the combinations of sites described in above-mentioned WO 2015/063580.

During and/or after implantation of tissue anchors 20 A, 20B, and 20C, a size of a tricuspid orifice is reduced by applying tension between first, second, and third tissue anchors 20A, 20B, and 20C. As mentioned above, first and second superelastic force modulators 30A and 30B, in response to a force being applied to third tissue anchor 20C by tissue at third site 3 IOC, distribute the force in a predetermined ratio between first and second tissue anchors 20A and 20B. For some applications, first and second tissue anchors 20A and 20B are first implanted, and third tissue anchor 20C is subsequently implanted.

Repairing tricuspid valve 300 typically facilitates reduction of atrioventricular valve regurgitation by altering the geometry of the tricuspid valve and/or by altering the geometry of the wall of the right atrium. In some applications of the present invention, implantation of tension system 10 achieves bicuspidization of the tricuspid valve. For such applications, the anterior leaflet and the septal leaflet are typically drawn together to enhance coaptation.

Alternatively, tension system 10 is applied to a mitral valve, or another bodily location where it is desired to anchor into or behind tissue for purposes of moving three sites closer to one another.

Reference is made to Figs. 1A-B and 2. For some applications, tension system 10 further comprises a pulley 400, which is typically connected (e.g., permanently fixed) to third tissue anchor 20C, such as by second tether 50B. Typically, first tether 50A is connected (e.g., permanently fixed) to first and second tissue anchors 20A and 20B and is moveable through pulley 400. Pulley 400 is arranged so as to achieve a desired distribution and transfer of forces between the tissue anchors, such as described in above- mentioned PCT Publication WO 2015/063580. The pulley is arranged such that the maximum load applied when implanting the last of the tissue anchors (e.g., third tissue anchor 20C) is transferred between the other two tissue anchors that were earlier implanted (e.g., first and the second tissue anchors 20A and 20B).

As used in the present application, including in the claims, a "pulley" is an element that transfers force along a tether, changing a direction of the force without substantially changing a magnitude of the force, while the tether moves through the pulley. As used herein, a pulley need not comprise a wheel, as is common in conventional pulleys. For some applications, a wheel is not necessary because the movement required during the cardiac cycle is reciprocal (back-and-forth) in nature, and limited in magnitude, about a few millimeters in each direction. It is noted that at some time after implantation, tissue growth may inhibit or entirely obstruct the tether's movement through the pulley, thereby disabling the pulley's "pulley" functionality. As used in the present application, including the claims, the feature that the tether is moveable through the pulley characterizes the pulley system at least at the time of implantation, but not necessarily after implantation. It is noted that if the pulley functionality is disabled after implantation, such as because of tissue growth, first and second superelastic force modulators 30A and 30B nevertheless continue to distribute the force applied by third tissue anchor 20C between first and second tissue anchors 20A and 20B, as described hereinabove. Tissue growth on superelastic force modulators 30A and 30B typically does not materially interfere with the functionality of the superelastic force modulators.

Alternatively, tension system 10 does not comprise pulley 400.

The scope of the present invention includes embodiments described in the following applications, which are assigned to the assignee of the present application and are incorporated herein by reference. For some applications, techniques and apparatus described in one or more of the following applications are combined with techniques and apparatus described herein: US Patent 8,475,525 to Maisano et al.; US Patent 8,961,596 to Maisano et al.; US Patent 8,961,594 to Maisano et al; PCT Publication WO 2011/089601; PCT Publication WO 2013/179295; PCT Publication WO 2013/011502; US Patent 9,241,702 to Maisano et al; US Provisional Application 61/750,427, filed January 9, 2013; US Provisional Application 61/783,224, filed March 14, 2013; US Provisional Application 61/897,491, filed October 30, 2013; US Provisional Application 61/897,509, filed October 30, 2013; US Patent 9,307,980 to Gilmore et al.; PCT Publication WO 2014/108903; PCT Publication WO 2014/141239; US Provisional Application 62/014,397, filed June 19, 2014; PCT Publication WO 2015/063580; US Patent Application Publication 2015/0119936; US Provisional Application 62/086,269, filed December 2, 2014; US Provisional Application 62/131,636, filed March 11, 2015; US Provisional Application 62/167,660, filed May 28, 2015; PCT Publication WO 2015/193728; PCT Publication WO 2016/087934; US Patent Application Publication 2016/0242762; PCT Publication WO 2016/189391; US Patent Application Publication 2016/0262741; US Provisional Application 62/376,685, filed August 18, 2016; US Provisional Application 62/456,206, filed February 8, 2017; US Provisional Application 62/456,202, filed February 8, 2017; US Provisional Application 62/465,410, filed March 1, 2017; US Provisional Application 62/465,400, filed March 1, 2017; US Provisional Application 62/516,894, filed June 8, 2017; US Provisional Application 62/530,372, filed July 10, 2017; and PCT Publication WO 2018/035378.

Patents and patent application publications incorporated by reference in the present patent application are to be considered an integral part of the application except that to the extent any terms are defined in these incorporated patents and patent application publications in a manner that conflicts with the definitions made explicitly or implicitly in the present specification, only the definitions in the present specification should be considered.

It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description.

Claims

1. A tension system for applying and distributing tension between first, second, and third sites in a patient's body, the tension system comprising:

first and second superelastic force modulators,

2. The tension system according to Claim 1, wherein the first and the second superelastic force modulators are configured to distribute the force equally between the first and the second tissue anchors.

3. The tension system according to Claim 1, wherein the first and the second superelastic force modulators are configured to distribute the force non-equally between the first and the second tissue anchors.

4. The tension system according to Claim 1, wherein the first and the second superelastic force modulators comprise respective superelastic wires including respective non-straight portions.

5. The tension system according to Claim 4, wherein the non-straight portions are coiled.

6. The tension system according to Claim 4, wherein the non-straight portions are curved.

7. The tension system according to Claim 6, wherein the non-straight portions are sinusoidal.

8. The tension system according to Claim 4, wherein the non-straight portions are zigzagged.

9. The tension system according to any one of Claims 1 -8, further comprising one or more tethers that couple the first tissue anchor to the third tissue anchor via the first superelastic force modulator, and the second tissue anchor to the third tissue anchor via the second superelastic force modulator.

10. The tension system according to Claim 9, wherein the first and the second superelastic force modulators are coupled to each other via exactly one tether.

1 1. A method for applying and distributing tension between first, second, and third sites in a patient's body, the method comprising:

12. The method according to Claim 1 1 , wherein the first and the second superelastic force modulators are configured to distribute the force equally between the first and the second tissue anchors.

13. The method according to Claim 1 1 , wherein the first and the second superelastic force modulators are configured to distribute the force non-equally between the first and the second tissue anchors.

14. The method according to Claim 1 1 , wherein the first and the second superelastic force modulators comprise respective superelastic wires including respective non-straight portions.

15. The method according to Claim 14, wherein the non-straight portions are coiled.

16. The method according to Claim 14, wherein the non-straight portions are curved.

17. The method according to Claim 16, wherein the non-straight portions are sinusoidal.

18. The method according to Claim 14, wherein the non-straight portions are zigzagged.

19. The method according to any one of Claims 1 1-18, wherein applying the tension comprises applying the tension between the first, the second, and the third tissue anchors via one or more tethers that couple the first tissue anchor to the third tissue anchor via the first superelastic force modulator, and the second tissue anchor to the third tissue anchor via the second superelastic force modulator.

20. The method according to Claim 19, wherein the first and the second superelastic force modulators are coupled to each other via exactly one tether.

21. The method according to any one of Claims 1 1-18, wherein moving the first, the second, and the third sites closer together comprises reducing a size of an atrioventricular valve orifice.

22. The method according to Claim 21 , wherein reducing the size of the atrioventricular valve orifice comprises reducing the size of the tricuspid valve orifice.

23. The method according to Claim 22, wherein the first and the second sites are in a vicinity of the tricuspid valve, and the third site is in a vein selected from the group of veins consisting of: a superior vena cava, an inferior vena cava, and a coronary sinus.