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Methods and apparatus for endovascularly replacing a patient's heart valve

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Methods and apparatus for endovascularly replacing a patient's heart valve


Methods for endovascularly replacing a patient's heart valve. In some embodiments, the method includes the steps of endovascularly delivering a replacement valve and an anchor to a vicinity of the heart valve, the anchor having a braid, and expanding the braid to a deployed configuration against the patient's tissue. The braid may be fabricated from a single strand of wire and/or may comprise at least one turn feature.

Browse recent Sadra Medical, Inc. patents - Los Gatos, CA, US
Inventors: Ulrich R. Haug, Hans F. Valencia, Robert A. Geshlider, Tom Saul, Amr Salahieh, Dwight P. Morejohn
USPTO Applicaton #: #20120330409 - Class: 623 219 (USPTO) - 12/27/12 - Class 623 
Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor > Heart Valve >Flexible Leaflet >Supported By Frame >Trileaflet

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The Patent Description & Claims data below is from USPTO Patent Application 20120330409, Methods and apparatus for endovascularly replacing a patient's heart valve.

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CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 12/028,452 Filed Feb. 8, 2008, which is a continuation of U.S. application Ser. No. 10/893,143 filed Jul. 15, 2004, now U.S. Pat. No. 7,329,279; which application is a continuation-in-part of U.S. application Ser. No. 10/746,280, filed Dec. 23, 2003. These applications are incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

Heart valve surgery is used to repair or replace diseased heart valves. Valve surgery is an open-heart procedure conducted under general anesthesia. An incision is made through the patient\'s sternum (sternotomy), and the patient\'s heart is stopped while blood flow is rerouted through a heart-lung bypass machine.

Valve replacement may be indicated when there is a narrowing of the native heart valve, commonly referred to as stenosis, or when the native valve leaks or regurgitates. When replacing the valve, the native valve is excised and replaced with either a biologic or a mechanical valve. Mechanical valves require lifelong anticoagulant medication to prevent blood clot formation, and clicking of the valve often may be heard through the chest. Biologic tissue valves typically do not require such medication. Tissue valves may be obtained from cadavers or may be porcine or bovine, and are commonly attached to synthetic rings that are secured to the patient\'s heart.

Valve replacement surgery is a highly invasive operation with significant concomitant risk. Risks include bleeding, infection, stroke, heart attack, arrhythmia, renal failure, adverse reactions to the anesthesia medications, as well as sudden death. Two to five percent of patients die during surgery.

Post-surgery, patients temporarily may be confused due to emboli and other factors associated with the heart-lung machine. The first 2-3 days following surgery are spent in an intensive care unit where heart functions can be closely monitored. The average hospital stay is between 1 to 2 weeks, with several more weeks to months required for complete recovery.

In recent years, advancements in minimally invasive surgery and interventional cardiology have encouraged some investigators to pursue percutaneous replacement of the aortic heart valve. See, e.g., U.S. Pat. No. 6,168,614. In many of these procedures, the replacement valve is deployed across the native diseased valve to permanently hold the valve open, thereby alleviating a need to excise the native valve and to position the replacement valve in place of the native valve.

In the endovascular aortic valve replacement procedure, accurate placement of aortic valves relative to coronary ostia and the mitral valve is critical. Some self-expanding valve anchors have had very poor accuracy in deployment, however. In a typical deployment procedure, the proximal end of the stent is not released from the delivery system until accurate placement is verified by fluoroscopy. The stent often jumps to another position once released, making it impossible to know where the ends of the stent will be after release with respect to the native valve, the coronary ostia and the mitral valve.

Also, visualization of the way the new valve is functioning prior to final deployment is very desirable. Due to the jumping action of some self-expanding anchors, and because the replacement valve is often not fully functional before final deployment, visualization of valve function and position prior to final and irreversible deployment is often impossible with these systems.

Another drawback of prior art self-expanding replacement heart valve systems is their relative lack of radial strength. In order for self-expanding systems to be easily delivered through a delivery sheath, the metal needs to flex and bend inside the delivery catheter without being plastically deformed. Expandable stent designs suitable for endovascular delivery for other purposes may not have sufficient radial strength to serve as replacement heart valve anchors. For example, there are many commercial arterial stent systems that apply adequate radial force against the artery wall to treat atherosclerosis and that can collapse to a small enough of a diameter to fit inside a delivery catheter without plastically deforming. However when the stent has a valve fastened inside it, and that valve must reside within the heart, as is the case in aortic valve replacement, the anchoring of the stent to vessel walls takes significantly more radial force, especially during diastole. The force to hold back arterial pressure and prevent blood from going back inside the ventricle during diastole will be directly transferred to the stent/vessel wall interface. Therefore, the amount of radial force required to keep the self-expanding stent/valve in contact with the vessel wall and not sliding is much higher than in stents that do not have valves inside of them. Moreover, a self-expanding stent without sufficient radial force will end up dilating and contracting with each heartbeat, thereby distorting the valve, affecting its function and possibly causing it to migrate and dislodge completely. Simply increasing strut thickness of the self-expanding stent is not a good solution as it increases profile and/or a risk of plastic deformation of the self-expanding stent.

In view of drawbacks associated with previously known techniques for endovascularly replacing a heart valve, it would be desirable to provide methods and apparatus that overcome those drawbacks.

SUMMARY

OF THE INVENTION

One aspect of the present invention provides methods for replacing a native aortic valve. Such methods involve endovascularly delivering a replacement valve and an anchor having an expandable braid. Delivery is preferably made to a site within the native aortic valve. Delivery is preferably made by actively foreshortening the anchor to radially expand the anchor to an expanded shape to secure the anchor at the anchor site. In some embodiments, the methods further include the step of locking the anchor in an expanded shape. In some embodiments, the methods include expanding a first step region of the anchor to a first diameter and a second region of the anchor to a second diameter larger than the first diameter.

In some embodiments, the foreshortening step of the methods herein comprises actively foreshortening the anchor to radially expand the anchor to an expanded shape to secure the anchor at the anchor site while avoiding interference with a mitral valve. In some embodiments, the foreshortening step comprises actively foreshortening the anchor to radially expand the anchor to a radially symmetrical expanded shape, a bilaterally symmetrical expanded shape or an asymmetrical expanded shape.

In some embodiments, the anchor is allowed to self-expand prior to the foreshortening step. In some embodiments, the foreshortening step comprises applying a proximally directed force on a deployment system interface at a proximal end or a distal end of the anchor. In some embodiments, the foreshortening step comprises applying a distally directed force on a deployment system interface at a proximal end of the anchor.

Incorporation By Reference

All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

FIGS. 1A and 1B are schematic top views of an anchor and valve apparatus in accordance with the present invention. FIG. 1 illustrates the apparatus in a collapsed delivery configuration within a delivery system. FIG. 1B illustrates the apparatus in an expanded configuration partially deployed from the delivery system.

FIGS. 2A-2F are schematic isometric views detailing an anchor of the apparatus of FIG. 1 in the collapsed delivery configuration and the expanded deployed configuration, as well as the full apparatus in the deployed configuration.

FIG. 3 is a schematic top view of an apparatus for fabricating braided anchors in accordance with the present invention.

FIGS. 4A-4D are schematic top views illustrating a method of using the apparatus of FIG. 3 to fabricate a braided anchor of the present invention.

FIGS. 5A-5O are schematic detail views illustrating features of braid cells at an anchor edge.

FIGS. 6A-6E illustrate further features of braid cells at an anchor edge.

FIGS. 7A-7J are schematic detail views terminations for one or more wire strands forming anchors of the present invention.

FIGS. 8A and 8B are schematic side views of alternative embodiments of the anchor portion of the apparatus of the present invention.

FIGS. 9A-9E are schematic side views of further alternative embodiments of the of the anchor portion of the apparatus of the present invention.

FIGS. 10A-10D are schematic views of different weave configurations.

FIGS. 11A-11E are schematic side views of various braided anchor configurations.

FIGS. 12A-12E are schematic side views of a deployment process.

FIGS. 13A and 13B illustrate a braided anchor in the heart.

FIGS. 14A and 14B illustrate a bilaterally symmetrical anchor and an asymmetric anchor, respectively.

DETAILED DESCRIPTION

OF THE INVENTION

The present invention relates to a delivery system, apparatus and methods for endovascularly delivering and deploying an aortic prosthesis within a patient\'s native heart valve, referred to here out as replacing a patients heart valve. The delivery system includes a sheath assembly and a guide wire for placing the apparatus endovascularly within a patient and a user control allowing manipulation of the aortic prosthesis. The apparatus includes an anchor and a replacement valve. The anchor includes an expandable braid. In preferred embodiments, the expandable braid includes closed edges. The replacement valve is adapted to be secured within the anchor, and as such, be delivered endovascularly to patient\'s heart to replace the patient\'s native heart valve. More preferably, the apparatus and methods of the present invention contemplate the replacement of a patient\'s aortic valve.

FIGS. 1A and 1B illustrate one embodiment of a delivery system and apparatus in accordance with the present invention is described. As illustrated by FIG. 1A, apparatus 10 may be collapsed for delivery within a delivery system 100. Delivery system 100 includes a guidewire 102, a nosecone 104, control tubes 106 coupled to a multi-lumen shaft 108, an external sheath 110 having a proximal handle 111, and a control handle 120. Delivery system 100 further comprises distal region control wires (not shown), which pass through one or more lumens of shaft 108 and are reversibly coupled to posts 32 of anchor 30 for manipulating a distal region of apparatus 10. The delivery system also comprises proximal region control wires 112 that pass through one or more lumens of shaft 108 and control tubes 106 (also known as fingers) to reversibly couple the control tubes to a proximal region of anchor 30. The control wires may comprise, for example, strands of suture, or metal or polymer wires.

Control handle 120 is coupled to multi-lumen shaft 108. A knob 122 disposed in slot 123 is coupled to the distal region control wires for controlling movement of the distal region of apparatus 10. Likewise, a knob 124 disposed in slot 125 is coupled to proximal region control wires 112 for control of the proximal region of apparatus 10. Handle 120 may also have a knob 126 for, e.g., decoupling the proximal and/or distal region control wires from apparatus 10, or for performing other control functions.

Apparatus 10 has an anchor 30 and a replacement valve 20. Anchor 30 preferably comprises a braid. Such braid can have closed ends at either or both its ends. Replacement valve 20 is preferably coupled to the anchor along posts 32. Post 32 therefore, may function as valve support and may be adapted to support the replacement valve within the anchor. In the embodiment shown, there are three posts, corresponding to the valve\'s three commissure points. The posts can be attached to braid portion of anchor 30. The posts can be attached to the braid\'s distal end, as shown in FIG. 2A, central region, or proximal end. Replacement valve 20 can be composed of a synthetic material and/or may be derived from animal tissue. Replacement valve 20 is preferably configured to be secured within anchor 30.

Anchor 30 has also a plurality of buckles 34 attached to its proximal region, one for each post 32. Posts 32 and buckles 34 form a two-part locking mechanism for maintaining anchor 30 in a deployed or expanded configuration (e.g., as illustrated in FIGS. 1B, 2B and 2C).

In this embodiment, anchor 30 is formed from collapsible and expandable wire braid. Anchor braid 30 is preferably self-expanding and is preferably formed from a material such as Nitinol, cobalt-chromium steel or stainless steel wire using one or more strands of wire. While the illustrated embodiment is formed from a single strand of wire, in other embodiments may benefit from a wire braid formed of 2-20 wires, more preferably 3-15 wires, or more preferably 4-10 wires.

Delivery and deployment of braided anchor 30 is similar to the delivery and deployment of the anchors described in U.S. patent application Ser. No. 10/746,280 filed Dec. 23, 2003, the disclosure of which is incorporated herein by reference. Specifically, in one embodiment described below, during deployment braided anchor 30 is actively foreshortened by proximally retracting the distal region control wires relative to control tubes 106 to expand and lock the anchor in place. In some embodiments, foreshortening expands anchor 30 to a radially symmetrical, bilaterally symmetrical, or asymmetrical expanded shape (as further described below). The foreshortening step can include expanding a first region of the anchor to a first diameter and a second region of the anchor to a second diameter larger than the first diameter. A third region may also be expanded to a diameter larger than the first diameter. The expansion of various regions of the anchor (e.g., the distal region) can be especially useful in locating the aortic valve and centering the anchor within it. Preferably, the secured anchor does not interfere with the mitral valve or the ostias. In some embodiments, the anchor is allowed to self expand prior to the foreshortening step.

As seen in FIG. 1, after endovascular delivery through sheath 110 to the vicinity of the patient\'s native valve (such as the aortic valve), apparatus 10 may be expanded from the collapsed delivery configuration of FIG. 1A to the expanded deployed configuration of FIG. 1B using delivery system 100. To deploy apparatus 10, external sheath 110 may be retracted relative to apparatus 10 by proximally retracting sheath handle 111 relative to control handle 120. Sheath 110 is thereby removed from the exterior of apparatus 10, permitting the anchor 30 to self-expand. In preferred embodiments, anchor 30 includes sheathing features as depicted in FIGS. 5B thru 5M or FIG. 6, 7A, or 7D adapted to reduce sheathing force. Sheathing force is defined as the force required to push the sheath distally over the anchor or the force required to pull the anchor proximally into the sheath (as for purposes of retrieving the anchor). For example, if anchor braid 30 is composed of a shape memory material, it may self-expand to or toward its “at-rest” configuration. This “at rest” configuration of the braid can be, for example its expanded configuration, a collapsed configuration, or a partially expanded configuration between the collapsed configuration and the expanded configuration. In preferred embodiments, the anchor\'s at-rest configuration is between the collapsed configuration and the expanded configuration. Depending on the “at rest” diameter of the braid and the diameter of the patient\'s anatomy at the chosen deployment location, the anchor may or may not self-expand to come into contact with the diameter of the patient\'s anatomy at that location.

In its collapsed configuration, anchor 30 preferably has a collapsed delivery diameter between about 3 to 30 Fr, or more preferably 6 to 28 Fr, or more preferably 12 to 24 Fr. In some embodiments, anchor 30 in its collapsed configuration will have a length ranging from about 5 to about 170, more preferably from about 10 to about 160, more preferably from about 15 to about 150, more preferably from about 20 to about 140 mm, or more preferably from about 25 mm to about 130.

Similarly, in its expanded configuration, anchor 30 preferable has a diameter ranging between about 10 to about 36 mm, or more preferably from about 24 to about 33 mm, or more preferably from about 24 to about 30 mm. In some embodiments, anchor 30 in its expanded configuration will have a length ranging from about 1 to about 50, more preferably from about 2 to about 40, more preferably from about 5 to about 30, or more preferably from about 7 to about 20 mm.

Overall, the ratio of deployed to collapsed/sheathed lengths is preferably between about 0.05 and 0.5, more preferably about 0.1 to 0.35, or more preferably about 0.15 to 0.25. In any of the embodiments herein, anchor 30 in its expanded configuration preferably has a radial crush strength that maintains the anchor substantially undeformed in response to a pressure of up to 0.5 atm directed substantially radially inward toward the central axis, or more preferably up to 2 atm directed substantially radially inward toward the central axis. In addition, in any of the embodiments herein, the anchor has an axial spring constant of between about 10 to 250 g/cm, more preferably between about 20 to 200 g/cm, or more preferably between about 40 to 160 g/cm. In addition, in any of the embodiments herein, the anchor is preferably adapted to support the replacement valve at the anchor site in response to a differential pressure of up to 120 mm Hg, more preferably up to 240 mm Hg, or more preferably up to 320 mm Hg.

These parameters are not intended to be limiting. Additional parameters within the scope of the present invention will be apparent to those of skill in the art.

As seen in FIG. 1B, anchor 30 may be expanded to a fully deployed configuration from a partial deployed configuration (e.g., self-expanded configuration) by actively foreshortening anchor 30 during endovascular deployment. As described in more detail in U.S. patent application Ser. No. 10/746,280, the distal region of anchor 30 may be pulled proximally via a proximally directed force applied to posts 32 via a distal deployment system interface. The distal deployment system interface is adapted to expand radially during application of a proximally directed force on the distal end of the anchor. In some embodiments, foreshortening of the apparatus involves applying a proximally directed force on a deployment system interface at the distal end of the anchor. In other embodiments, foreshortening of the apparatus involves applying a distally directed force on a deployment system interface at the proximal end of the anchor. More preferably, proximally or distally directed forces on the deployment system interface do not diametrically constrain the opposite end of the anchor--distal or proximal end, respectively. When a proximally directed force is applied on the deployment system interface, it is preferably applied without passing any portion of a deployment system through a center opening of the replacement valve.

The distal deployment system interface may include control wires that are controlled, e.g., by control knob 122 of control handle 120. Similarly, the proximal regions of anchor 30 may be pushed distally via a proximal deployment system interface at the proximal end of the anchor. The proximal deployment system interface is adapted to permit deployment system to apply a distally directed force to the proximal end of anchor 30 through, e.g., fingers 106, which are controlled by, e.g., Control knob 124 of control handle 120. The proximal deployment system interface may be further adapted to expand radially during application of a distally directed force on the proximal end of the anchor. Preferably, the proximal deployment system interface is adapted to permit deployment system to apply a distally directed force on the proximal end of the anchor system through a plurality of deployment system fingers or tubes 106. Such expansion optionally may be assisted via inflation of a balloon catheter (not shown) reversibly disposed within apparatus 10, as described in U.S. application Ser. No. 10/746,280.

Once anchor 30 is fully deployed, posts 32 and buckles 34 of anchor 30 may be used to lock and maintain the anchor in the deployed configuration. In one embodiment, the control wires attached to posts 32 are threaded through buckles 34 so that the proximally directed force exerted on posts 32 by the control wires during deployment pulls the proximal locking end of posts 32 toward and through buckles 34. Such lock optionally may be selectively reversible to allow for repositioning and/or retrieval of apparatus 10 during or post-deployment. Apparatus 10 may be repositioned or retrieved from the patient until the two-part locking mechanism of posts 32 and buckles 34 of anchor 30 have been actuated. When the lock is selectively reversible, the apparatus may be repositioned and/or retrieved as desired, e.g., even after actuation of the two-part locking mechanism. Once again, further details of this and other anchor locking structures may be found in U.S. patent application Ser. No. 10/746,280. Locking mechanisms used herein may also include a plurality of levels of locking wherein each level of locking results in a different amount of expansion. For example, the proximal end of the post can have multiple configurations for locking within the buckle wherein each configuration results in a different amount of anchor expansion.



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stats Patent Info
Application #
US 20120330409 A1
Publish Date
12/27/2012
Document #
13591680
File Date
08/22/2012
USPTO Class
623/219
Other USPTO Classes
International Class
61F2/24
Drawings
24



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