The present technology relates generally to devices and methods for providing protection against emboli entering the aortic arch vessels (e.g., the brachiocephalic, left common carotid and left subclavian arteries) as well as the downstream vessels branching from the aorta (e.g., the celiac, mesenteric, renal, gonadal and iliac arteries). Many embodiments of the technology relate to protecting patients from emboli created or dislodged by the passage and deployment of transaortic devices, such as Transcatheter Aortic Valve Replacement (“TAVR”) devices, catheters or cannulae.
Procedures involving the placement and delivery of catheters and devices retrograde through the aorta to the heart have led to a growing concern for the potential of neurological complications, such as stroke, and other organ infarction due to emboli created or released by the deployment and use of transaortic devices, transmitral device, catheters, cannulae or other therapeutic devices. Emboli may include calcified plaques, artheromatous fragments, thrombus, fat globules, air or gas bubbles, clumps of bacteria or other foreign material, tissue remnants or tumor cells. The emboli may travel to downstream vessels and cause infarction (i.e., tissue death caused by a local lack of oxygen due to obstruction of the tissue's blood supply).
Embolic material can be created or released during therapeutic procedures because of mechanical trauma, such as abrasion, bumping, bending, torqueing, dilation or expansion of the often atherosclerotic walls of the aorta, calcified heart valves, or other diseased or thrombus containing structures of the cardiovascular system. Other potential causes of emboli may include the physiological stress induced by the procedure and aggravation of underlying conditions such as valve disease, atrial fibrillation and structural heart defects leading to the incidental release of thrombus. Air emboli or particulates released from the device are also potential sources of emboli.
Devices to protect patients from emboli have been proposed or introduced with limited success. Such existing devices are generally placed percutaneously with a catheter through the radial, brachial or subclavian artery, or through the femoral artery to the aortic arch under fluoroscopic guidance. Many existing devices, however, have drawbacks such as merely deflecting or diverting embolic matter as opposed to effectively capturing and retaining emboli, traumatizing the vessel wall, and several other drawbacks explained in more detail below. Accordingly, there is a need for devices and methods that address one or more of these deficiencies.
The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments of the present technology, and, together with the general description given above and the detailed description given below, serve to explain the features of the present technology.
Specific details of several embodiments of the technology are described below with reference to
With regard to the terms “distal” and “proximal” within this description, unless otherwise specified, the terms can reference a relative position of the portions of an embolic protection device and/or an associated delivery device with reference to an operator and/or a location in the vasculature. For example, proximal can refer to a position closer to the operator of the device or an incision into the vasculature, and distal can refer to a position that is more distant from the operator of the device or further from the incision along the vasculature. For ease of reference, throughout this disclosure identical reference numbers are used to identify similar or analogous components or features, but the use of the same reference number does not imply that the parts should be construed to be identical. Indeed, in many examples described herein, identically numbered parts of individual embodiments are distinct in structure and/or function. The headings provided herein are for convenience only.
With regard to anatomical terminology, most patients have three arteries branching off the aortic arch: the brachiocephalic artery ostium, left common carotid artery ostium, and left subclavian artery ostium. However, in a minority of patients, the left common carotid artery ostium and the left subclavian artery ostium may be merged such that the patient effectively only has two arteries branching from the aortic arch.
Systems, devices and methods provided herein for protecting against emboli entering the aortic arch vessels and/or other downstream vessels branching from the aorta in accordance with several embodiments of the technology are generally used during minimally invasive cardiac procedures. In one embodiment, the embolic protection device has a low-profile configuration (i.e., undeployed) for delivery through the vasculature and an expanded configuration (i.e., deployed) for temporary placement within a patient's arterial system. The embolic protection device may include a filter portion comprising a mesh configured to allow sufficient blood flow through the vasculature while retaining emboli for eventual removal from the patient. In some embodiments, the embolic protection device may further include a proximal portion attached to or integrated with the filter portion, and the proximal portion extends proximally (e.g., downstream) from the filter portion. In the expanded configuration, the filter portion can have a first filter section with a first cross-sectional dimension configured to anchor the embolic protection device at least within the ascending aorta at a location distal to the brachiocephalic artery ostium. The first filter section can have a length and cross-sectional dimension configured to cover the ostia of the aortic arch vessels in a manner that prevents emboli from entering the aortic arch vessels while allowing sufficient blood flow through the ostia. In selected embodiments, the filter may also include a tapered second filter section extending proximally from the first filter section. The tapered second filter section, for example, may start tapering from the first filter section at a point along the length of the device near or downstream of the left subclavian artery ostium. The filter may include one or more layers of self-expanding meshes (e.g., braided material), and the proximal portion may extend proximally (e.g., downstream) from the second filter section of the filter to an extracorporeal location.
Several embodiments of the technology include devices and methods wherein at least a portion of emboli in the bloodstream are deflected from entering a branch vessel of the aorta, and then captured within a space between the embolic protection device and the therapeutic device downstream of the aortic arch. Several embodiments, for example, continue to capture and deflect emboli in the blood stream through the descending aorta.
As shown in
The mesh layer of the filter portion 12 may comprise a braided mesh of filaments (e.g., wires, threads, sutures, fibers, etc.) that have been configured to form a porous fabric or structure for collecting and retaining emboli while simultaneously allowing passage of filtered blood through the vasculature, as shown in cut-away areas C1 and C2 of
Referring to
As illustrated in
The second filter section 16 extends proximally from the transition region 15 to the proximal end 12b of the filter portion 12. When deployed, a second filter section 16 may have a second cross-sectional dimension D2 (
The length of the second section 16 can be selected such that, when deployed, the proximal zone 12b of the filter portion 12 may be located within the descending aorta DA or at any point along the aorta downstream of the left subclavian ostium 34a (e.g., the thoracic aorta, the abdominal aorta, the iliac branch, or the femoral artery). In some embodiments, the second section 16 of the filter portion 12 may have a length that extends from the transition region 15 to an inner diameter of an access site introducer sheath and/or an extracorporeal location 24.
Referring to
As shown in
Optionally, the embolic protection device may be constructed to elute or deliver of one or more beneficial drug(s) and/or other bioactive substances into the blood or the surrounding tissue. In some embodiments, one or more eluting filament(s) may be interwoven into the mesh to provide for the delivery of drugs, bioactive agents or materials with a mild inflammatory response as disclosed herein. The interwoven filaments may be woven into the mesh structure after heat treating (as discussed below) to avoid damage to the interwoven filaments by the heat treatment process.
Optionally, the device may be coated with various polymers to enhance its performance, fixation and/or biocompatibility. Optionally, the device may incorporate cells and/or other biologic material to promote sealing, reduction of leak or healing.
In any of the above embodiments, the device may include a drug or bioactive agent to enhance the performance and/or healing of the device, including: an antiplatelet agent, including but not limited to aspirin, glycoprotein IIb/IIIa receptor inhibitors (including, abciximab, eptifibatide, tirofiban, lamifiban, fradafiban, cromafiban, toxifiban, XV454, lefradafiban, klerval, lotrafiban, orbofiban, and xemilofiban), dipyridamole, apo-dipyridamole, persantine, prostacyclin, ticlopidine, clopidogrel, cromafiban, cilostazol, and nitric oxide.
In any of the above embodiments, the device may include an anticoagulant such as heparin, low molecular weight heparin, hirudin, warfarin, bivalirudin, hirudin, argatroban, forskolin, ximelagatran, vapiprost, prostacyclin and prostacyclin analogues, dextran, synthetic antithrombin, Vasoflux, argatroban, efegatran, tick anticoagulant peptide, Ppack, HMG-CoA reductase inhibitors, and thromboxane A2 receptor inhibitors.
Access to the ascending aorta or other vessels of the heart can be accomplished through the patient's vasculature in a percutaneous manner. By percutaneous it is meant that a location of the vasculature remote from the heart is accessed through the skin, typically using a surgical cut down procedure or a minimally invasive procedure, such as using needle access through, for example, the Seldinger technique. The ability to percutaneously access the remote vasculature is well-known and described in the patent and medical literature. Once percutaneous access is achieved (for example, through the femoral or iliac arteries), the interventional tools and supporting catheter(s) may be advanced to the heart intravascularly and positioned within the aorta in a variety of manners, as described herein.
After the distal zone 70a of the delivery catheter 70 is at a target location in the ascending aorta at a location distal of the brachiocephalic artery ostium 30a, the guidewire 68 and obturator 74 are removed proximally (e.g., downstream) through the lumen of the delivery catheter 70. Next, the sheath 73 is retracted proximally and an exposed portion of the EPD 10 expands (
As shown in
After completing the interventional procedure, the interventional catheter is removed in a proximal (e.g., downstream) direction through the lumen of the EPD 10 and then the EPD is removed from the patient.
The filter portion 12 includes at least one mesh material or layer. In selected embodiments, the mesh may comprise a braided material of filaments (e.g., wires, threads, sutures, fibers, etc.) configured to form a porous fabric or structure. The filter portion may include two or more layers of mesh materials. In some embodiments, braid filaments of varying diameters may be combined in the same layer or portions of the layer to impart different characteristics including, e.g., stiffness, elasticity, structure, radial force, pore size, embolic filtering ability, and/or other features. For example, in the embodiment shown in
The filaments of the braided mesh can be arranged in a generally axially elongated configuration when the EPD 10 is within the delivery catheter or the retrieval catheter. Certain embodiments of the filaments have a filament braid angle “a” from about 5 to 45 degrees with respect to the longitudinal axis of the device such that the filaments are angled toward the longitudinal dimension of the EPD 10. In the expanded or deployed configuration, the braid angle a of the filaments can be from 45 to about 85 degrees with respect to the longitudinal axis of the device. The expanded braided mesh can conform to or otherwise contact the vessels without folds along the longitudinal axis. The cross-sectional dimension of the mesh in the expanded state can be from 5 mm to 50 mm, or from 10 mm to 40 mm in selected embodiments. The diameters of the braided mesh within the delivery catheter and within the retrieval catheter be from 2 mm to 15 mm, or from 5 mm to 10 mm in more specific applications.
The mesh can be constructed using metals, polymers, composites, and/or biologic materials. Polymer materials can include Dacron, polyester, polypropylene, nylon, Teflon, PTFE, ePTFE, TFE, PET, TPE, PLA silicone, polyurethane, polyethylene, ABS, polycarbonate, styrene, polyimide, PEBAX, Hytrel, poly vinyl chloride, HDPE, LDPE, PEEK, rubber, latex, or other suitable polymers. Other materials known in the art of elastic implants can also be used. Metal materials can include, but are not limited to, nickel-titanium alloys (e.g. Nitinol), platinum, cobalt-chrome alloys, 35N LT, Elgiloy, stainless steel, tungsten or titanium. In certain embodiments, metal filaments may be highly polished or surface treated to further improve their hemocompatibility. In some embodiments, it is desirable that the mesh be constructed solely from metallic materials without the inclusion of any polymer materials, i.e., polymer free. In these embodiments and others, it is desirable that the entirety of the embolic protection device be made of metallic materials free of any polymer materials. It is believed that the exclusion of polymer materials in some embodiments may decrease the likelihood of thrombus formation on device surfaces, and it is further believed that the exclusion of polymers and the sole use of metallic components can provide an embolic protection device with a thinner profile that can be delivered with a smaller catheter as compared to devices having polymeric components.
The terms “formed,” “preformed” and “fabricated” may include the use of molds or tools that are designed to impart a shape, geometry, bend, curve, slit, serration, scallop, void, hole in the elastic, superelastic, or shape memory material or materials used in the components of the embolic protection device, including the mesh. These molds or tools may impart such features at prescribed temperatures or heat treatments.
For braided portions, components, or elements, the braiding process can be carried out by automated machine fabrication or can also be performed by hand. For some embodiments, the braiding process can be carried out by the braiding apparatus and process described in U.S. Pat. Publication No. 8,261,648, filed Oct. 17, 2011 and entitled “Braiding Mechanism and Methods of Use” by Marchand et al., which is herein incorporated by reference in its entirety. In some embodiments, a braiding mechanism may be utilized that comprises a disc defining a plane and a circumferential edge, a mandrel extending from a center of the disc and generally perpendicular to the plane of the disc, and a plurality of actuators positioned circumferentially around the edge of the disc. A plurality of filaments are loaded on the mandrel such that each filament extends radially toward the circumferential edge of the disc and each filament contacts the disc at a point of engagement on the circumferential edge, which is spaced apart a discrete distance from adjacent points of engagement. The point at which each filament engages the circumferential edge of the disc is separated by a distance “d” from the points at which each immediately adjacent filament engages the circumferential edge of the disc. The disc and a plurality of catch mechanisms are configured to move relative to one another to rotate a first subset of filaments relative to a second subset of filaments to interweave the filaments. The first subset of the plurality of filaments is engaged by the actuators, and the plurality of actuators is operated to move the engaged filaments in a generally radial direction to a position beyond the circumferential edge of the disc. The disc is then rotated a first direction by a circumferential distance, thereby rotating a second subset of filaments a discrete distance and crossing the filaments of the first subset over the filaments of the second subset. The actuators are operated again to move the first subset of filaments to a radial position on the circumferential edge of the disc, wherein each filament in the first subset is released to engage the circumferential edge of the disc at a circumferential distance from its previous point of engagement.
The filter portion can have one or more braids along its whole length or only a portion of its length. In several embodiments, the filter portion has only a single mesh layer, but in other embodiments the filter portion has a plurality of the same or different layers of mesh material.
The filtering braid 102 can have small pores that filter and/or retain the emboli. The filtering braid 102, for example, can be a braid with an average effective pore size between about 0.05 mm and about 0.25 mm. The ratio of the effective pore size of the structural braid 100 to the filtering braid 102 can be between about 1.5 and 6. The difference between the effective pore size of the structural braid 100 and the effective pore size of the filtering braid 102 can be between about 0.100 and 0.800 mm. The effective pore size can be determined by measuring more than about 5 pores around the periphery of the EPD 10 where the pores tend to reach a maximum and averaging the numbers.
The filtering braid 102 and the structural braid 100 may have different braid counts. In some embodiments, the braided filament count for the filtering braid 102 is greater than 290 filaments per inch. In one embodiment, the braided filament count for the filtering braid 102 is between about 360 to about 780 filaments per inch, or in further embodiments between about 144 to about 290 filaments per inch. In one embodiment, the braided filament count for the structural braid 100 is between about 72 and about 144 filaments per inch, or in other embodiments between about 72 and about 162 filaments per inch. In some embodiments, the device 100 may include polymer filaments or fabric within the braid(s) 100, 102 or between layers of braids.
The filtering braid 102 and the structural braid 100 may also be comprised of braided filaments having different diameters. For example, in some embodiments, the filtering braid 102 comprises filaments having an average diameter less than 0.04 mm, and the structural braid 100 can have filaments with an average diameter from about 0.07 mm to about 0.20 mm. In other embodiments, the filtering braid 102 comprises filaments having an average diameter of 0.025 mm. In addition, the ratio of the average diameters of the filaments of the structural braid 100 to the average diameters of the filaments of the filtering braid 102 can be from 2:1 to 12:1. In some embodiments, the thickness of the filaments of the structural braid 100 are less that about 0.5 mm. For example, the structural braid 100 may be fabricated from wires or filaments having diameters ranging from about 0.015 mm to about 0.25 mm. In some embodiments, the thickness of the braid filaments of the filtering braid 102 are less that about 0.25 mm. In further embodiments, the structural braid 100 and/or the filtering braid 102 can comprise braids having mixed filament diameters (e.g., thickness).
In the embodiment shown in
The braid angle a of the structural braid 100 can be approximately the same as the braid angle a of the filtering braid 102 at corresponding points along the length of the device. In one embodiment, the braid angles of the structural braid 100 and the filtering braid 102 can vary together along the length L of the filter. For example, the filter can have a first region R1 with a first braid angle α1 and a second region R2 with a second braid angle α2 that is different than α1. Within the first region R1, the structural braid 100 and the filtering braid 102 both have approximately the first braid angle α1. Within the second region R2, the structural braid 100 and the filtering braid can both have approximately the second braid angle α2, which is different than the first braid angle α1. Although the embodiment shown in
In embodiments with multiple layers of braids, the layers or some of the layers can be held at one or more ends by a common connecting member or hub, while the other end is a free end that is not held by a connecting member or hub. The free ends of the braid layers enable the layers to have different lengths without bunching of the layers upon collapse for delivery or retraction by a catheter because the layers can move relative to each other to accommodate compression into a contracted state. The characteristics of the structural layer or braid material can remain constant as the braid continues around the everted portion at an edge 104, or it can be formed with two or more braiding techniques so that the braiding on the inside for the inner layer 100b is different than the braiding on the outside for the external layer 100a. For example, the braiding can change to provide differing braid angles or pore sizes.
From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the scope of the invention. Accordingly, the invention is not limited except as by the appended claims.
The present application claims priority to U.S. Provisional Application No. 61/566,531, filed Dec. 2, 2011, entitled “EMBOLIC PROTECTION DEVICES AND METHODS,” and U.S. Provisional Application No. 61/646,833, filed May 14, 2012, entitled “EMBOLIC PROTECTION DEVICES AND METHODS,” the full disclosures of which are incorporated herein by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US12/67479 | 11/30/2012 | WO | 00 | 6/3/2014 |
Number | Date | Country | |
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61566531 | Dec 2011 | US | |
61646833 | May 2012 | US |