Cardiac valve delivery devices and systems

A delivery device includes a central elongate structure, a sheath, a plurality of tethers extending through the central elongate structure configured to hold a cardiac valve, a cutting mechanism, a handle, and a control. The sheath is configured to slide over the central elongate structure. The cutting mechanism is configured to cut the tethers upon activation to release the cardiac valve. The handle is connected to the central elongate structure. The control on the handle is configured to activate the cutting mechanism.

FIELD

The present invention relates generally to the treatment of cardiac valve disorders, such as mitral valve replacement, using minimally invasive techniques. In particular, this application is directed towards devices for delivering and placing replacement mitral valves.

BACKGROUND

The mitral valve lies between the left atrium and the left ventricle of the heart. Various diseases can affect the function of the mitral valve, including degenerative mitral valve disease and mitral valve prolapse. These diseases can cause mitral stenosis, in which the valve fails to open fully and thereby obstructs blood flow, and/or mitral insufficiency, in which the mitral valve is incompetent and blood flows passively in the wrong direction.

Many patients with heart disease, such as problems with the mitral valve, are intolerant of the trauma associated with open-heart surgery. Age or advanced illness may have impaired the patient's ability to recover from the injury of an open-heart procedure. Additionally, the high costs associated with open-heart surgery and extra-corporeal perfusion can make such procedures prohibitive.

Patients in need of cardiac valve repair or cardiac valve replacement can be served by minimally invasive surgical techniques. In many minimally invasive procedures, small devices are manipulated within the patient's body under visualization from a live imaging source like ultrasound, fluoroscopy, or endoscopy. Minimally invasive cardiac procedures are inherently less traumatic than open procedures and may be performed without extra-corporeal perfusion, which carries a significant risk of procedural complications.

Prosthetic valve replacement procedures can be difficult, and various factors are generally taken into account when placing the valve. First, the prosthetic valve should be placed at the same or very nearly the same angle as the native valve. A valve that is off axis could cause turbulent blood flow and/or potential para-valvular leaks. Second, the prosthetic valve should ideally have concentricity. This means that the valve is placed in the same center as the native valve. An off center deployment or valve placement could affect the mechanism of neighboring valves or the heart's conductive system. Finally, the prosthetic valve should be at the proper depth within the patient's heart with respect to the location of the native valve, as otherwise, the prosthetic valve may interfere with the conductive nature of the heart as well.

A safe and efficient delivery system and method for replacement of a cardiac valve that addresses some or all of these concerns is described herein.

SUMMARY

In general, in one embodiment, a delivery device includes a central elongate structure, a sheath, a plurality of tethers extending through the central elongate structure, a cutting mechanism, a handle, and a control. The sheath is configured to slide over the central elongate structure. The cutting mechanism is configured to cut the tethers upon activation. The handle is connected to the central elongate structure. The control on the handle is configured to activate the cutting mechanism.

This and other embodiments can include one or more of the following features. The delivery device can further include an annular member including a plurality of pockets extending radially around the central elongate structure. Each of the tethers can include a feature on a distal end thereof configured to fit within a pocket of the plurality of pockets to hold the tether in place. A distal portion of the annular member can be configured to telescope relative to a proximal portion of the annular member. The delivery device can further include a second control on the handle configured to move the sheath proximally and distally over the central elongate structure. The cutting mechanism can include a resistive wire that is configured to be heated to cut the plurality of tethers. The delivery device can further include an o-ring configured to hold the plurality of tethers against the resistive wire. The resistive wire can be positioned within an annular member configured to hold distal ends of the plurality of tethers. The cutting mechanism can include a resistive plate that is configured to be heated to cut the plurality of tethers. The resistive plate can include a plurality of holes therethrough. Each tether can be configured to pass through a hole of the plurality of holes. The delivery device can further include an o-ring configured to hold the plurality of tethers against the resistive wire. The plurality of tethers can be made of polyether ether ketone or ultra-high molecular weight polyethylene. The cutting element can be a metallic ring or coil. The cutting element can be a resistive heating element. The resistive heating element can be configured to heat the plurality of tethers to a temperature of greater than 190° F. The cutting element can be a rotatable grinder. The cutting element can be a rotatable blade. The delivery device can further include a coiled spring configured to place tension on the plurality of tethers.

In general, in one embodiment, a method of delivering a prosthetic mitral valve includes: (1) extending a prosthetic delivery device into a heart with the prosthetic mitral valve collapsed within a sheath of the delivery device; (2) sliding the sheath to expose a first anchor of the prosthetic valve, thereby allowing the anchor to self-expand to an expanded annular configuration on a first side of the mitral valve annulus; (3) loosening a plurality of tethers of the delivery device so as to allow a second anchor to self-expand to an expanded annular configuration on a second side of the mitral valve annulus, the expansion of the proximal anchor causing the first anchor to move towards the second anchor and capture tissue of the mitral valve annulus between the proximal anchor and the distal anchor; (4) cutting the tethers with a cutting mechanism of the delivery device to release the tethers from the second anchor; and (5) removing the delivery device from the heart.

This and other embodiments can include one or more of the following features. The cutting mechanism can include a resistive heating element, and cutting the tethers can include heating the resistive heating element. Cutting the tethers can include heating the tethers to a temperature of greater than 190° F. to melt and sever the tethers. The tethers can be melted and severed in less than 1 minute.

DETAILED DESCRIPTION

The delivery devices described herein can be used to deliver and deploy a wide variety of replacement heart valves, such as prosthetic valves adapted to be minimally invasively delivered. Exemplary prosthetic valves that can be delivered and deployed include the expandable prosthetic valves described in U.S. patent application Ser. No. 14/677,320, filed Apr. 2, 2015, in U.S. Pat. No. 8,870,948, in International Patent Application No. PCT/US2016/032550, filed May 13, 2016, titled “REPLACEMENT MITRAL VALVES,” and in U.S. patent application Ser. No. 14/677,320, filed Apr. 2, 2015, titled “REPLACEMENT CARDIAC VALVES AND METHODS OF USE AND MANUFACTURE,” all of which are incorporated by reference herein. For example, the delivery devices herein are configured to be able to delivery and deploy a replacement heart valve, such as a mitral valve, that includes distal and proximal anchors.

FIGS. 1A-1Cshows an embodiment of an exemplary prosthetic valve replacement delivery device700. The delivery device700includes a device proximal end702and a device distal end704. As can be seen fromFIGS. 1A through 1C, the delivery device700has an elongated portion that terminates at a nosecone706at the device distal end704. The nosecone706is coupled to a central stem718, which is in turn coupled to a tether ends retainer720. The elongated portion includes an outer sheath712and an inner sheath716. The central stem718also couples to a series of tether/suture maintaining hypodermic tubes that are able to slide along the central stem718. The inner sheath716is configured to slide relative to the central stem718(extend and retract) to cover or expose certain retaining features of the delivery device, e.g., the tether ends retainer720(seeFIG. 1B), as well as aid with maintaining the prosthetic valve within the delivery device700prior to deployment. The device proximal end702includes a handle709for holding onto the delivery device.FIG. 1Bshows a close-up of the distal end of the delivery device700, where it is more apparent that the nosecone706is attached to the central stem718and the central stem718is coupled to a tether ends retainer720.FIG. 1Cshows a cross-sectional view of the delivery device700.

Referring toFIG. 2, tethers726aid with maintaining the prosthetic valve within the device700. Tethers726can be made, for example, of suture materials. The tethers726extend along and around the center stem718, and each tether726threads through a separate tubular structure782. The tether ends that couple to the tether retainer720can further include a feature, e.g., a sphere, for coupling the tether ends to the tether retainer720. The distal ends of the tethers can be configured to loop through the proximal end of the prosthetic valve. The distal ends of the tethers, once looped through the proximal end of the valve, can be maintained by the tether retainer720.

Another exemplary delivery device300is shown inFIGS. 3A-3B. The device300is similar to device700and includes central stem318coupled to a tether ends retainer120and a distal nosecone306. The central stem318also couples to a series of tether/suture maintaining hypodermic tubes382that are configured to slide along the central stem318. An inner sheath316is configured to slide inside an outer sheath312and relative to the central stem318(extend and retract) to cover or expose certain retaining features of the delivery device, e.g., the tether ends retainer120, as well as aid with maintaining the prosthetic valve within the delivery device300prior to deployment.

A close-up of the tether retainer120is shown inFIGS. 4A-4B. The tether retainer120includes a central channel111extending axially therethrough and series of tether pockets124extending around the outer circumference of the retainer120. The tether pockets124are configured to hold the features at the distal end of the tethers726. Thus, the tether pockets124can have shape that corresponds to the shape of the tether ends. For example, the pockets124can be spherical in shape so as to hold a spherical ball (from the distal end of a tether) therein. Further, an annular indent122can extend circumferentially around the tether retainer120. Two holes134a,bcan extend from the central channel111to the annular ring122. Moreover, the tether retainer120can include a groove166extending from each of the pockets124to the annular indent122and on to the distal end of the retainer120.

Referring toFIG. 4C-4D, a pair of conductive wires144a,b, e.g., copper wires, can extend through the inner diameter of the elongated portion or sheath of the delivery device, through the channel111, and through the holes134a,b. The conductive wires144a,bcan terminate in a resistive wire155, such as Nichrome, that sits within the annular ring122. Referring toFIG. 4D, a plurality of tethers726(only one is shown for clarity) can also extend through the inner diameter of the elongated portion of the delivery device and through the channel111. The tethers726can extend out the distal end of the retainer120and then extend back through the channel166in the outer diameter of the retainer120and over the resistive wire155. The distal ends of the tethers can be lodged within pockets to hold the ends in place, as described above. During use of the delivery device, an o-ring can be configured to sit over the resistive wire155within the annular ring122to hold the tethers thereon. When electricity is conducted through the wires144a,b, it will flow to the resistive wire155, which will heat up. The heat of the resistive wire155(against which the tethers sit) can cause the tethers to melt at the point of contact, thereby severing or cutting the distal ends of the tethers from the proximal ends of the tethers and allowing the delivery device to be removed from the valve while keeping the valve in place within the body (e.g., within the mitral valve annulus).

An exemplary method of loading tethers into the retainer120is shown inFIGS. 5A-5E. InFIG. 5A, the o-ring156can be moved to be positioned over the pockets124. InFIG. 5B, a tether726(e.g., a UHMWPE suture) with a distal end feature796(e.g., a 1.5 mm tantalum ball) can be threaded through the inner diameter of the delivery device, out the distal end of the retainer120, and positioned such that the distal end feature796is proximate to a pocket124. InFIG. 5C, the feature796has been positioned partially inside of the pocket124and underneath the o-ring156. InFIG. 5D, the feature796has been placed fully inside the pocket124. In this position, the tether726runs within the groove166and sits against the resistive wire155. InFIG. 5E, the o-ring156is moved into place within the annular indent122, which presses the tether726firmly against the resistive wire155. The o-ring156can also function to thermally and electrically insulate the resistive wire155from the blood stream.

In some embodiments, referring toFIG. 6, the retainer120can include a double loop of resistive wire155extending therearound within the annular indent122.

Referring toFIGS. 7A and 7B, in some embodiments, a tether retainer220can include a distal resistive plate277rather than a resistive wire. The plate277can include a plurality of holes278therein, such as around the circumference. Tethers726can be extended through the holes278, and the distal end of each tether can be placed in a pocket, as described above. To release the tethers, the resistive plate277can be heated, causing the portion of the tethers touching the walls of the plate277to melt and sever. As shown inFIG. 7B, an o-ring256can be used to insulate the plate from the blood stream and/or to maintain the sutures in contact with the plate277.

Referring toFIG. 8, in some embodiments, a distal portion891tether retainer820can be configured to telescope relative to the proximal portion881of the retainer820. Tethers826can extend along the length of the tether tubes882, over the distal end of the retainer820, and back into the pockets824. Further, the distal portion891can move distally relative to the proximal portion881to allow the ends896of the tethers826to be positioned in the pockets824and then can be moved proximally again to hold the ends of the tethers826in place. The distal portion891can advantageously help place pressure on the tethers826to push them against the resistive wire855. The distal portion891can further help isolate the resistive wire855from the blood during use to avoid shorting. An o-ring856can additionally shield the resistive wire855from the blood stream.

In some embodiments, the tether pockets can be designed or shaped so as to allow the distal ends of the tethers to be placed therein during loading of the valve on the delivery device, but can be designed so as to prevent the end of the tether from being removed during use.

In some embodiments, the retainers described herein can be made of polyether ether ketone (PEEK). In other embodiments, the retainers can be made of a ceramic, such as Macor.

The resistive heating element can be placed at various locations along the length of the device (i.e., it does not have to be part of the tether ends retainer and/or be located near the distal end of the shaft). For example,FIG. 9shows a device900with various locations for the heating element. The heating element, for example, can be in a distal position at the tether ends retainer (location991), mid-way along the shaft (location993), at the distal end of the handle (location995), or at the proximal end of the handle by the controls (location997). In any or all of the locations, a shield jacket (e.g., made of ceramic) can be used to separate the heating element from the rest of the device and/or the blood.

An exemplary device1000having a resistive heating element1111positioned along the mid-shaft is shown inFIGS. 10A-10C. The resistive heating element1111is thus positioned between the handle1009and the tether ends retainer1020. The resistive heating element1111can be, for example, a metallic cylindrical element with a plurality of notches, a notch coil, or a coil wire. Further, the heating element1111can be positioned circumferentially around the tether tubes1082. Cylindrical ceramic elements1099can be positioned around the heating element1111and can be used to electrically shield the heating element1111from the rest of the shaft. A seal can further be used to isolate the heating element from fluid (i.e., to avoid shorting the heating element1111). In some embodiments, the tether tubes1082can be actuated linearly (e.g., to move the tethers linearly) while the resistive heating element1111stays stationary. In other embodiments, the resistive heating element1111can move with the tubes1082(e.g., within a water tight housing). Because the resistive heating element1111is located along the mid-shaft rather than towards the distal end of the shaft, the heating element1111can advantageously be kept away from the heart during use of the device.

Another exemplary device1100is shown inFIGS. 11A-11B. The device1100includes a resistive cutting drum1101that is configured to be placed mid-way along the shaft that includes a resistive plate1177sandwiched by spacers1112a,b(to electrically isolate the plate1177). In some embodiments, the plate1177can further include a seal1144a,b(e.g., silicone) on one or both ends to prevent fluid from contacting the plate1177. The drum1101can further include a plurality of holes1078therein configured to allow the tethers to extend therethrough. In some embodiments, the resistive cutting drum1101can be configured to slide with the tether tubes1182to prevent having to move the tethers through the seals1144a,b.

Referring toFIGS. 12A-12G, the resistive heating element(s) described herein can be attached to the delivery devices described herein in a variety of ways. For example, the resistive element1201acan be wrapped or place directly against the tether tubes1292, as shown in FIG.12A. Alternatively, as shown inFIGS. 12B-12C, the resistive element1201bcan be wrapped around a large tube1288that then houses the smaller tether tubes therein. In some embodiments, referring toFIG. 12D, a slot1289can be formed in the outer diameter of the large tube1288to constrain the resistive element1201cand get it closer to direct contact with the tether tubes1292(i.e., to make it easier to heat the tethers therein). Further, as shown inFIGS. 12E-G, in some embodiments, a jacket assembly1212can be used to shield the heating element1201dfrom the rest of the catheter, and house wire junctions (e.g., in bores1221a,b).

In some embodiments, the voltage applied to the conductive wires of the resistive heating elements described herein can be between 2-3V and the current can be between 2-4A.

One or more shield elements (such as ceramic elements1099) can be used with any heating element described herein. The shield elements can help protect other elements of the delivery device while allowing a greater amount of power to be used to melt the tethers, thereby reducing the time that it takes to cut the tethers.

The tethers described herein for use with a resistive heating element can be a variety of materials that are subject to melting. For example, the tethers can be made of ultra-high molecular weight polyethylene.

In some embodiments, the heating elements used with the devices described herein can heat the tethers to a temperature of greater than 190° F., such as greater than 200° F., greater than 210° F., or greater than 220° F.

FIGS. 13A-15Dshow alternative mechanisms for cutting tethers that can be used in addition to or in place of the resistive heating elements described herein. For example,FIGS. 13A-13Bshow a grinding mechanism1313have a rotatable grinder1315. The rotatable grinder1315can be positioned so as to push the tethers1326slightly radially outwards when not in use. As a result, when the grinder1315rotates, it can rotate against the tethers1326so as to slice therethrough. As shown, the tethers1326can still be positioned within tether tubes1392, but the tether tubes1392can include a break therein at the rotatable grinder1315.

FIGS. 14A-14Bshow a razor mechanism1414that can include a plurality of radially extending arms1418(seeFIG. 14A;FIG. 14Bdoes not show the arms1418for clarity) extending in the space1490between hypotubes1492. The arms1418are designed to extend between each set of tethers1426until rotated. Once rotated, the arms1418can slice through the tethers1426(that extend out of the hypotubes1492).

FIGS. 15A-15Dshow a delivery device1500including a sheath1515, tether1526, and a tether ends retainer1520(as described above). Further, the delivery device1500can include a razor cutting mechanism1515that can include a coiled spring1520configured to clamp the tethers1526either between the coils or against an inner or outer shaft. The spring1520can have a variable diameter so as to hold the tethers1526taught at a set location. A blade1514extending from the exterior thereof (FIG. 15A) or in the interior thereof (FIGS. 15B-D) can then be configured to rotate to cut through the tether1526. In some embodiments, a spring actuator1551can be pulled back to unclamp the spring1520and release the tethers1526. The spring mechanism can advantageously hold a set tension on the tethers1526, which can aid in cutting of the tethers1526.

In some embodiments, the methods for melting or cutting tethers described herein can cause severing within less than 2 minutes, such as less than 1 minute, less than 45 seconds, less than 30 seconds, less than 20 seconds, or less than 10 seconds.

The tether cutting mechanisms described herein can be used with other embodiments of delivery devices in addition to the specific delivery devices described herein. For example, the tether cutting mechanisms can be used as a component in addition to or in place of any component of any of the delivery devices described in U.S. PCT Application No. PCT/US16/32546, titled “CARDIAC VALVE DELIVERY DEVICES AND SYSTEMS,” filed May 13, 2016, incorporated by reference herein.

The delivery devices described herein can advantageously be used to control the placement of the prosthetic valve at the mitral valve site, as described in U.S. PCT Application No. PCT/US16/32546, titled “CARDIAC VALVE DELIVERY DEVICES AND SYSTEMS,” filed May 13, 2016, incorporated by reference herein.

Although described herein for use with a mitral valve prosthetic, the delivery systems described herein can be used with a variety of different implantable devices, including stents or other valve prosthetics.