The present disclosure relates generally to medical devices, and particularly, to endoluminal prostheses with induction triggered anchors and systems for deploying such prostheses and methods for the manufacture and use of the same for repair of damaged vessels, ducts, or other physiological pathways.
Various interventions have been provided for weakened, aneurysmal, dissected or ruptured vessels, including surgical interventions and endovascular interventions. Endovascular interventions generally include inserting an endoluminal device or prosthesis such as a stent or stent graft into the damaged or diseased body lumen to provide support for the lumen, and to exclude damaged portions thereof. Such prosthetic devices are typically positioned at the point of treatment or target site by navigation through the vessel, and possibly other connected branch vessels, until the point of treatment is reached. This navigation may require the device to be able to move axially through the vessel(s) prior to deployment, while still maintaining the ability to exert an outward force on the interior wall once deployed.
In the field of aortic interventions, endoluminal devices are placed in vessels to address and correct diseased tissue resulting from atherosclerotic plaques, aneurysm or weakening of body vessel walls, and arterial dissection. In the case of atherosclerosis, plaque buildup results in narrowing of the vessel which may lead to reduced or blocked blood flow within the body vessel. Endoluminal device for atherosclerosis acts to radially expand the narrowed area of the body vessel to restore normal blood flow. In the case of an aneurysm, a weakening of the body vessel wall results in ballooning of the body vessel which can eventually lead to rupture and subsequent blood loss. In some cases, the aneurysmal sac may include plaque. Endoluminal device for aneurysms acts to seal off the weakened area of the body vessel to reduce the likelihood of the body vessel rupture. In the case of arterial dissection, a section of the innermost layer of the arterial wall is torn or damaged, allowing blood to enter false lumen divided by the flap between the inner and outer layers of the body vessel. The growth of the false lumen may eventually lead to complete occlusion of the actual artery lumen. Endoluminal device for dissection healing would reappose the dissection flap against the body vessel wall to close it off and restore blood flow through the true lumen.
Aortic aneurysms and dissection in certain regions are challenging to medically treat. For example, when such conditions occur in the ascending aorta, it has been challenging to implant endoluminal devices because there has been minimal means of securely anchoring such device in the region, which is already highly weakened and malformed from extreme enlargement. To further complicate the matter, the proximity to the aortic valve wall and large pulsatile pressure from the heart may result in device migration and/or endoleaks. A better device is needed to treat this area of the body, as well as other areas of the body.
In order to address issues surrounding treatment of aortic aneurysms, embodiments of stents and stent grafts are disclosed below.
In one example, a device is disclosed having a stent frame made up of a single stent unattached to any graft material, where the stent frame is expandable from a compressed position to an expanded position. The device may include at least one anchor element coupled to the stent frame, the anchor element may include a thermal activatable material, the anchor element having a first configuration disposed about an anchor axis and configured to pierce a wall of a separate medical device and a body tissue wall, and a second configuration in response to a temperature rise in the anchor element to draw the body tissue wall closer to the wall of the separate medical device, wherein the anchor axis defined in the first configuration is substantially perpendicular to the longitudinal axis, and wherein, in response to said temperature rise, the anchor element maintains alignment substantially with the anchor axis to inhibit tearing of the pierced body tissue wall by the anchor element. The device may be used to repair endoleaks that develop between the separate medical device and the body tissue wall.
In another example, a medical device having a longitudinal axis, the medical device is disclosed. The medical device may have a stent frame comprising a plurality of single stent portions unattached to any graft material and arrange in series along a common longitudinal axis, the stent frame expandable from a compressed position to an expanded position. The medical device may further each of the plurality of single stent portions linked to at least one other of the plurality of single stent portions with an inter-stent link, the at least one inter-stent link comprising a flexible material. Further, the medical device may include at least one anchor element coupled to the stent frame, the anchor element comprising a thermal activatable material, the anchor element having a first configuration disposed about an anchor axis and configured to pierce a body tissue wall, and a second configuration in response to a temperature rise in the anchor element to draw the body tissue wall closer to the wall of the separate medical device, wherein the anchor axis defined in the first configuration is substantially perpendicular to the longitudinal axis, and in response to said temperature rise, the anchor element maintains alignment substantially with the anchor axis to inhibit tearing of the pierced body tissue wall by the anchor element.
In another example, a medical device disposed about a longitudinal axis including a device body and at least one anchor element. The anchor element is coupled to the device body, and includes a thermal activatable material. The anchor element includes a first configuration and a second configuration. In the first configuration, the anchor element is disposed about an anchor axis and configured to pierce a body tissue wall. In the second configuration, in response to a temperature rise in the anchor element, the anchor element is configured to draw the pierced body tissue wall closer to the device body. The anchor axis is defined in the first configuration and is substantially perpendicular to the longitudinal axis. In response to said temperature rise, the anchor element maintains alignment substantially with the anchor axis to inhibit tearing of the pierced body tissue wall by the anchor element.
In another example, a delivery system for deployment of a prosthesis within a body vessel is provided. The system includes an outer sheath and a prosthesis. The outer sheath is coaxially disposed over an inner cannula, and the outer sheath and the inner cannula define a retention region. The prosthesis includes a prosthesis body resiliently movable between a radially compressed configuration and a radially expanded configuration, and a plurality of thermal activatable anchor elements coupled along the body. The thermal activatable anchor elements include a delivery configuration when the prosthesis is in the radially compressed configuration. When the prosthesis is in the radially expanded configuration, the thermal activatable anchor elements include a first deployed configuration and a second deployed configuration. The prosthesis is disposed along the retention region and retained in the radially compressed configuration by the outer sheath. With retraction of the outer sheath, the prosthesis is movable to the radially expanded configuration and the thermal activatable anchor elements are resiliently movable from the delivery configuration to the first deployed configuration to pierce a body tissue wall of a body vessel. In response to an increase in temperature of the thermal activatable anchor elements in the first deployed configuration, the thermal activatable anchor elements are movable to a second deployed configuration to bring the prosthesis body and the pierced body tissue wall relatively closer to one another.
In yet another example, a delivery system for deployment of a prosthesis within a body vessel in a step-wise manner is described. The delivery system may include a magnetically shielded outer sheath coaxially disposed over an inner cannula, the outer sheath and the inner cannula defining a retention region. The magnetically shielded outer sheath may consist of a magnetic shielding material. The prosthesis may include a prosthesis body resiliently movable between a radially compressed configuration and a radially expanded configuration, and a plurality of thermal activatable anchor elements coupled along the body, the thermal activatable anchor elements including a delivery configuration when the prosthesis is in the radially compressed configuration, and, when the prosthesis is in the radially expanded configuration, the thermal activatable anchor elements include a first deployed configuration and a second deployed configuration, where the prosthesis is disposed along the retention region and retained in the radially compressed configuration by the outer sheath, wherein, with retraction of the magnetically shielded outer sheath, the prosthesis is movable to the radially expanded configuration and the thermal activatable anchor elements are resiliently movable from the delivery configuration to the first deployed configuration to pierce a body tissue wall of a body vessel. In response to an increase in temperature of the thermal activatable anchor elements in the first deployed configuration, the thermal activatable anchor elements are movable to a second deployed configuration to bring the prosthesis body and the pierced body tissue wall relatively closer to one another.
In another example, a method of deploying a prosthesis within a body vessel is provided. The method includes one or more of the following steps. A step includes introducing a prosthesis into a body vessel at a treatment site. The prosthesis includes a prosthesis body and a plurality of anchor elements coupled along the prosthesis body. A step includes radially expanding the prosthesis within the body vessel such that the anchor elements are in a first deployed configuration for piercing a wall of the body vessel at the treatment site. A step includes heating the anchor elements of the radially expanded prosthesis with an inductive heating source for moving the anchor elements from the first deployed configuration to a second deployed configuration where at least a portion of the anchor elements have an enlarged configuration along an abluminal side of the pierced body vessel such that the prosthesis and the pierced body vessel wall are moved relatively closer to one another.
Other devices, systems, methods, features and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be within the scope of the invention, and be encompassed by the following claims.
The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views.
Medical devices for implantation within a human or animal body for repair of damaged vessels, ducts, or other physiological pathways are provided. The medical devices include at least one active anchor element for fully piercing the vessel wall. The active anchor element is retractable to pull the tissue radially inward by progressively coiling or looping the anchor wire tip upon localized heating of the anchors, such as, for example, by induced heat triggering. The potential hemorrhage in piercings by the anchor elements may be inhibited by a covering or coating of SIS or other hemorrhaging inhibiting substance or material along the medical device. To this end, the active anchor elements may be capable of safely reshaping an aneurysmal site and/or pull-back a detached outer tissue layer or dissection flap of the aorta to the tunica intima. Other body vessel, duct or pathway diseases or reshaping are possible. A delivery system for such medical device may also be provided. The delivery system may include a retractable outer sheath to cover the anchor elements during delivery within the body. Balloon membranes may be a part of the system for selective expansion and targeted radial pressure of the anchor elements outward during piercing. An induction device used with such medical devices may also be provided to provide localized thermal energy to the active anchor elements for facilitating the transformation for pulling the tissue relatively closer with the medical device. By having the balloon(s) be a part of the system, the physician may more quickly pierce the tissue with inflation of the balloon(s) within the medical device in vivo for the application of the localized heating in less steps and less time, thereby improving the procedure time and avoiding delays for healing.
In the present application, the term “proximal end” is used when referring to that end of a medical device closest to the heart after placement in the human body of the patient, and may also be referred to as inflow end (the end that receives fluid first), and the term “distal end” is used when referring to that end opposite the proximal end, or the one farther from the heart after its placement, and may also be referred to as the outflow end (that end from which fluid exits).
Medical device 10 may be any device that is introduced temporarily or permanently into the body for the prophylaxis or therapy of a medical condition. For example, such medical devices may include, but are not limited to; endovascular grafts, stent grafts, bifurcated stent grafts or assembly of a multicomponent prosthesis, stents, meshes, vascular grafts, stent-graft composites, filters (for example, vena cava filters), vascular implants, tissue scaffolds, myocardial plugs, valves (for example, venous valves), various types of dressings, endoluminal prostheses, vascular supports, or other known biocompatible devices.
Now looking more closely at the drawings,
It is understood from the figures that the medical device 10 may have a plurality of anchor elements 20.
In one example, the anchor tip 40 may have a dull tip configured for penetrating the body tissue wall and less likely to pierce unintended body tissues after piercing through the relevant body tissue wall. At least a partial number of anchor elements 20 may have the same anchor length AL. The anchor length AL may be selected based on the profile and relative dimensions of the diseased body vessel. It is contemplated that at least a partial number of anchor elements 20 have different lengths (see, for example,
The anchor element 20 comprises a thermal activatable material, such as, for example, a shape memory material, such that the anchor element may include multiple configurations for delivery and deployment. In one example, the thermal activatable material anchor element has two defined geometries for deployment. The anchor element may have delivery configuration. In the delivery configuration, the anchor element 20 may be positioned in a manner to reduce the overall profile of the medical device, which is shown in
The anchor element 20 made of a thermal activatable wire material may be biased into a straight elongated geometry having a first cross-sectional area 43 and shape in a first deployment configuration at a first temperature range, as shown in
At a second temperature, greater than the first temperature range, such as provided by localized temperature increase within the anchor element 20 either from external to the body or inside the vessel, the anchor element 20 changes from its biased configuration to a second deployment configuration, as shown in
In the second deployment configuration, the anchor element 20 includes an enlarged portion 45 having a second cross-sectional area 46 and shape. The transformation of the anchor element shape between the first and second deployment configurations places the anchor tip 40 and the enlarged portion 45 relatively closer to the device body 12. The enlarged portion 45 may be spaced from the base 42 by a distance of body vessel wall W thickness. For example, in response to a temperature rise in the anchor element 20, during the transformation to the second deployment configuration, the enlarged portion 45 of the anchor element 20 draws the pierced body tissue wall W closer to the device body 12, as shown, for example, in
The enlarged portion 45 may be formed into a variety of shapes.
When considering the various arrangements, the anchor elements 20 may have a common first and second deployment configuration size and shape. In another example, at least one anchor element 20 may have a different first deployment configuration and/or second deployment configuration size and shape relative to other anchor elements. For example, a portion of the anchor elements 20 may not be made of the thermal activatable material and thus may only have the delivery configuration and the first deployment configuration. In another example, the shape and position of the enlarged portion 45 may vary across the anchor members 20 depending on their relative location along the body vessel wall, when such differences may be beneficial for enhanced anchoring capability.
As discussed above, the thermal activatable material, such as, for example, a shape memory material may be use for the anchor elements 20. The shape memory material may be at least one of a metal, a metal alloy, a nickel titanium alloy, and a shape memory polymer. Shape memory alloys have the desirable property of becoming rigid, that is, returning to a remembered state, when heated above a transition temperature. A shape memory alloy suitable for the present invention is Ni—Ti available under the more commonly known name Nitinol. When this material is heated above the transition temperature, the material undergoes a phase transformation from martensite to austenite, such that material returns to its remembered state. The transition temperature is dependent on the relative proportions of the alloying elements Ni and Ti and the optional inclusion of alloying additives. In one embodiment, the anchor element is made from Nitinol with a austenite start temperature (As) and austenite finish temperature (Af), for example, 104° F. to 176° F. (40° C. to 80° C.) that is higher than normal body temperature of humans, which is about 98.6° F. Thus, when the medical device 10 is deployed in a body vessel and exposed to normal body temperature, the anchor element 20 will be maintained in its first deployment configuration state. When heated, such as with inductive heating, the alloy of the anchor element 20 will transform to austenite, that is, the remembered state, into one of the shapes disclosed above for the second deployment configuration. When the inductive heating source is removed, the anchor element 20 is allowed to cool to transform the material to martensite which is more ductile than austenite, with the anchor element 20 maintaining the general shape of its austenite state.
As generally understood by those skilled in the art, martensite start temperature refers to the temperature at which a phase transformation to martensite begins upon cooling for a nickel-titanium shape memory alloy, and martensite finish temperature refers to the temperature at which the phase transformation to martensite concludes. Austenite start temperature (As) refers to the temperature at which a phase transformation to austenite begins upon heating for a nickel-titanium shape memory alloy, and austenite finish temperature (Af) refers to the temperature at which the phase transformation to austenite concludes.
The thermal activatable material, such as, for example, a shape memory material alloy, may be cold worked into desired anchor element shapes (e.g., shapes associated with the second deployment configuration described above) by, for example, drawing, rolling, or another forming method. Mandrels with posts may be used for the various coil and/or looped patterns described herein. The cold working typically involves several forming passes in combination with interpass annealing treatments at temperatures in the range of from about 600° C. to about 800° C. The interpass annealing treatments soften the material between cold work passes, which typically impart 30-40% deformation to the material. Machining operations, such as, for example, drilling, cylindrical centerless grinding, or laser cutting may also be employed to fabricate the desired component (e.g., the sharp or dull tipped anchors). A heat treatment may be employed to impart a “memory” of a desired high temperature shape and to optimize the shape memory/superelastic and mechanical properties of the anchor element. The number, duration and the temperature of the heat treatments may affect the transformation temperatures. Typically, heat treatment temperatures of 400° C. to 550° C. may be appropriate to set the final shape and to optimize the properties.
Anchor elements 20 may be may be made of shape memory alloys, such as, for example, ferromagnetic materials, that respond to changes in magnetic field. Anchor elements made from a ferromagnetic shape memory effect transforms from the martensite phase where the anchor elements are in the first deployment configuration to the austenite phase where the anchor elements are in the second deployment configuration when exposed to an external magnetic field. The term “ferromagnetic” as used herein is a broad term and is used in its ordinary sense and includes, without limitation, any material that easily magnetizes, such as a material having atoms that orient their electron spins to conform to an external magnetic field. Ferromagnetic materials include permanent magnets, which may be magnetized through a variety of modes, and materials, such as metals, that are attracted to permanent magnets. Ferromagnetic materials also include electromagnetic materials that are capable of being activated by an electromagnetic transmitter, such as one located external to patient. Ferromagnetic materials may include one or more polymer-bonded magnets, wherein magnetic particles are bound within a polymer matrix, such as a biocompatible polymer. The magnetic materials can comprise isotropic and/or anisotropic materials, such as for example NdFeB (neodymium-iron-boron), SmCo (samarium-cobalt), ferrite and/or AlNiCo (aluminum-nickel-cobalt) particles. Examples of ferromagnetic shape memory alloys include Fe—C, Fe—Pd, Fe—Mn—Si, Co—Mn, Fe—Co—Ni—Ti, Ni—Mn—Ga, Ni2MnGa, Co—Ni—Al, and the like. Certain of these shape memory materials may also change shape in response to changes in temperature. Thus, the shape of such materials can be adjusted by exposure to a magnetic field, by changing the temperature of the material, or both.
In one example, the system 100 includes at least one inflatable balloon membrane 130 disposed at the proximal region of the inner cannula 106 to define one or more balloons. A dual-balloon device configuration will be described in detail, and it is understood that additional balloons may be similarly applied to the system for more accurate targeting. One such balloon device having four balloons that may be utilized is described in U.S. Patent Application Publ. 2008/0103443 to Kabrick et al. filed Oct. 26, 2007, assigned to Cook Incorporated, which is incorporated herein in its entirety.
In one example shown in
Inflation fluid may be introduced into the inflation lumens 138, 142, such as, for example, distal ends 150, 152 of respective inflation lumens 138, 142. The inflation fluid traverses through the inflation lumens 138, 142 and exits the respective side ports 136, 140 to fill the corresponding balloon membranes 130, 132. The independent expansion and variable radial cross-sectional areas of the first balloon 130 and the second balloon 132 permits relative positioning of the catheter body within the body vessel, such as, for example, shown in
With reference to
Outlet ports (two outlet ports 180, 182 shown) are disposed on the wall of the handle body 158. One or both outlet ports 180, 182 may be fluidly coupled with the fluid reservoir 162 via a fluid outlet passage (two outlet passages 184, 186 shown) defined within the handle body 158. The outlet ports 180, 182 may be configured for fluidly coupling the respective inflation lumens 138, 142 to the corresponding fluid outlet passages 184, 186.
The fluid reservoir 162 may include a first chamber 190 and a second chamber 192 separated from another via a piston 194 in slidably sealable contact along the inner walls 196 of the fluid reservoir 162. The first chamber 190 is in fluid communication with the first balloon 130 via the first fluid outlet passage 184, the first outlet port 180, the first inflation lumen 138 and the first inflation side port 136. The second chamber 192 is in fluid communication with the second balloon 132 via the second fluid outlet passage 186, the second outlet port 182, the second inflation lumen 142 and the second inflation port 140. Slidable movement of the piston 194 within the inflation fluid reservoir 162 selectively increases or decreases fluid volumes of the respective first and second chambers 190, 192. In one example, the piston 194 is coupled to an operable lever 200 externally disposed relative to the handle body 158. The operable lever 200 may be slidably disposed within an elongated slot 201 formed in the handle body 158. The walls defining the slot 201 guide the movement of the lever 200.
In an example when the first and second balloons 130, 132 have a common volume and/or expansion cross-sectional area and the first and second chambers 190, 192 have a common volume, the operable lever 200 moved in the proximal direction operably moves the piston 194 within the fluid reservoir 162 in the proximal direction P to reduce the volume of the first chamber 190, which increases the cross-sectional area of expansion of the first balloon 130, and to increase the volume of the second chamber 192, which reduces the cross-sectional area of expansion of or deflates the second balloon 132. The lever 200 at this proximal position brings the catheter body 102 away from the body vessel center eccentrically to a first side of the body vessel wall, as shown in
In one example, the at least one balloon is disposed proximal to the loaded medical device, such as shown in the illustrations in
The at least one balloon may be at least partially disposed within the loaded medical device, as shown in
The induction device 250 may include a handheld or portable body 252 for grasping the device and a trigger switch 254 for selectively activating and deactivating an electromagnetic field (EMF) energy. The EMF energy may be focused to provide directional heating to the active anchor elements 20 of the medical device 10. Housed within the body is an electromagnetic field energy (EMF) generator 260 to generate the EMF energy field that penetrates the body of the patient and induces a current within the active anchor element 20 to a treatment site within a patient to perform the medical procedure. The EMF generator 260 may include an electrically conductive coil. The induced current within the anchor elements 20 is suitable to heat the active anchor element and cause the thermal activatable material to transform from the first deployment configuration to the second deployment configuration.
An electrical controller 262 may be housed within the body 252. The controller 262 may be in electrical communication with the trigger switch 254, a power supply 264, and the EMF generator 260. The controller 262 may generally include a processor and a memory. The memory may retrievably store one or more algorithms, data, predefined relationships between different induction device parameters, preprogrammed models, such as in the form of lookup tables and/or maps, or any other information that may be accessed by the controller and relevant to the operation of the induction device. The body housing of the controller 262 may be an enclosed structure that is configured to house circuitry and/or various circuit elements that measure the EMF energy and determine when the EMF energy reaches a predetermined level. The circuits may be hardware and/or analog circuits comprised of analog components that perform analog operations. In one example, at least some of the circuits may include digital circuitry, such as microprocessors, microcontrollers, integrated circuits, digital hardware logic, or other similar types of digital circuits configured to perform digital operations and/or execute software to perform energy measurement and timing operations. Switching circuitry may be included in the controller 262 and configured to pulsate the EMF generator 260. Pulsating the EMF generator 260 may provide better control of the thermal energy being delivered and the induced current heating the active anchor elements 20. The anchor elements 20 may be selectively heated using short pulses of EMF energy having an on and off period between each cycle. The energy pulses provide segmented heating.
Blocking and matching circuitry may be included with the controller 262. The matching circuitry may be configured to match the impedance of the output load and the output impedance of the EMF generator 260. The blocking circuitry may be configured to prevent direct current and/or low frequency components of the EMF energy from being communicated to the output. The controller 262 may also include energy measurement circuitry and/or logic to determine an amount of energy and to compare with a threshold energy level, so that the energy may be cut off or ramped up. The controller 262 may include power circuitry to control for power the circuitry and the generator. The power circuity electrically coupled to the power supply 264, such as a 120 volt AC source, a step down transformer and AC modulator 270. The power circuity may include a battery power source 272 that may be operably coupled to the circuitry and/or the 120 volt AC source for charging. A heat sink 274 may be provided to regulate heating of the induction device. An insulator 275 may be provided at the tip of the induction device to inhibit electrical energy of the induction device from direct contact to the patient's body.
The controller 262 may measure the EMF energy being delivered to the treatment site and determine when the EMF energy reaches a predetermined level. When the EMF energy reaches the predetermined energy level, the controller 262 may inhibit further EMF energy from being delivered to the medical device. The predetermined EMF energy level may be a selected amount of energy to be delivered to the treatment site for performing the medical procedure. When more than the predetermined EMF energy level is delivered, harm or injury may be caused to the patient, such as burning of tissue at the treatment site. Alternatively, when less that the predetermined EMF energy level is delivered, the medical procedure may be unsatisfactorily performed, such as by failing to pull the tissue relatively closer to the implanted medical device. As such, the controller 262 may be and/or provide a control and safety mechanism for the EMF generator.
The device housing body 252 may include an indicator 280, and the controller 262 may include an indication circuitry configured to output an indication of EMF energy being supplied to the medical device 10. In one example embodiment, the indication circuitry includes a light emitting diode (LED) or liquid crystal displace (LCD) that outputs a light signal or is “on” when the EMF signals are being sent and does not output a light signal or is “off” when EMF energy is not being supplied. In alternative example embodiments, the indication circuitry may include circuitry in addition to or other than an LED, such as speaker or a display device that outputs an audio and/or a visual signal to indicate whether EMF energy is being supplied to the medical device. The indication circuitry may be useful to and/or used by an operator of the EFM generator, which may identify when to cease application of the EMF energy (e.g., by removing finger off of trigger switch) by observing the indication, such as when the LED turns from “on” to “off.”
The term “graft” describes an object, device, or structure that is joined or that is capable of being joined to a body part to enhance, repair, or replace a portion or a function of that body part. Grafts that can be used to repair body vessels include, for example, films, coatings, or sheets of material that are formed or adapted to conform to the body vessel that is being enhanced, repaired, or replaced. The graft material may include a biocompatible synthetic or biomaterial. Examples of suitable synthetic materials include fabrics, woven and nonwoven materials, and porous and nonporous sheet materials. Other synthetic graft materials include biocompatible materials such as polyester, polytetrafluoroethylene (“PTFE”), polyurethane (“PU”), fluorinated ethylene propylene (“FEP”) and the like. Examples of suitable biocompatible materials include, for example, pericardial tissue and extracellular matrix materials (“ECMM”) such as SIS.
Other synthetic materials, such as biocompatible synthetic materials, may be used for the graft material. Synthetic materials may include polymers such as, for example, poly(urethanes), poly(siloxanes) or silicones, poly(ethylene), poly(vinyl pyrrolidone), poly(2-hydroxy ethyl methacrylate), poly(N-vinyl pyrrolidone), poly(methyl methacrylate), poly(vinyl alcohol), poly(acrylic acid), polyacrylamide, poly(ethylene-co-vinyl acetate), poly(ethylene glycol), poly(methacrylic acid), polylactides (“PLA”), polyglycolides (“PGA”), poly(lactide-co-glycolid-es) (“PLGA”), polyanhydrides, polyorthoesters or any other similar synthetic polymers that may be developed that are biocompatible. Biocompatible synthetic polymers also may include copolymers, blends, or any other combinations of the forgoing materials either together or with other polymers generally. The use of these polymers will depend on given applications and specifications required. Suitable polymer material may include, for example, polyester such as DACRON™, polyetherurethanes such as THORALON® from Thoratec Corporation (Pleasanton, Calif.), or polyethylene terephthalate (“PET”).
In addition, materials that are not inherently biocompatible may be subjected to surface modifications in order to render the materials biocompatible. Examples of surface modifications include graft polymerization of biocompatible polymers from the material surface, coating of the surface with a crosslinked biocompatible polymer, chemical modification with biocompatible functional groups, and immobilization of a compatibilizing agent such as heparin or other substances. Thus, any polymer that may be formed into a porous sheet can be used to make a graft material, provided the final porous material is biocompatible. Polymers that can be formed into a porous sheet include polyolefins, polyacrylonitrile, nylons, polyaramids and polysulfones, in addition to polyesters, fluorinated polymers, polysiloxanes and polyurethanes as listed above. Preferably the porous sheet is made of one or more polymers that do not require treatment or modification to be biocompatible.
The graft material, the coating, or one class of materials for electrospinning may also include extracellular matrix materials. The “extracellular matrix” is typically a collagen-rich substance that is found in between cells in animal tissue and serves as a structural element in tissues. Such an extracellular matrix is preferably a complex mixture of polysaccharides and proteins secreted by cells. The extracellular matrix can be isolated and treated in a variety of ways. Following isolation and treatment, it is referred to as an “extracellular matrix material,” or ECMM. ECMMs may be isolated from submucosa (including small intestine submucosa), stomach submucosa, urinary bladder submucosa, tissue mucosa, renal capsule, dura mater, liver basement membrane, pericardium or other tissues.
The stent or support frame structures may be any device or structure that provides or is configured to provide rigidity, expansion force, or support to a body part, for example, a diseased, damaged, or otherwise compromised body lumen. Such stent frame structure may include any suitable biocompatible material, including, but not limited to fabrics, metals, plastics, and the like. Examples of suitable materials include metals such as stainless steel and nitinol, and plastics such as PET, PTFE and polyurethane. The stent frame structure may be “expandable,” that is, it may be capable of being expanded to a larger-dimension configuration. The stent frame structure may expand by virtue of its own resilience (i.e., self-expanding), upon the application of an external force (i.e., balloon-expandable), or by a combination of both. In one example, the stent frame structure may have one or more self-expanding portions and one or more balloon-expandable portions. The stent struts, also referred to herein as portions, that are interconnected to one another represents specific configurations of a wire member that comprises a basic structural component of the stent. As used herein, the term “wire” refers to any filamentary member, including, but not limited to, drawn wire and filaments that have been laser cut from a cannula. For example, the stent architecture with the intricate mating elements that form the interlocking joints may lend itself to being manufacture from a metal cannula laser cut to the desired pattern as described. The shape, size, and dimensions of the stent structure may vary. The size of these components and the overall stent structure is determined primarily by the diameter of the vessel lumen at the intended implant site, as well as the desired length of the overall stent device. The stent structure and/or ring structures may have a common cross-sectional area along the body or may vary to have different cross-sectional areas.
In
A delivery system without a balloon may be removed and another balloon catheter may be positioned within the expanded medical device. Alternatively, the system 102 with the balloon(s), such as described above, may be repositioned or the position maintained within the expanded medical device 10. Inflation fluid may be introduced to the balloons 130, 132 for selectively expanding at least one of the inflatable balloons to apply targeted radial pressure within the expanded medical device 10 and potentially expand the medical device beyond its nominal expanded diameter such that the relevant anchor elements 20 pierce the aortic aneuryzed wall 309. The piercing action may allow the anchor tips to extend beyond the aortic aneuryzed wall 309 to the abluminal side 310 of the ascending aorta 304.
In
As shown in
In
In
A therapeutically effective amount of a bioactive agent may be applied to the anchor elements and/or graft covering of the medical device for facilitating treatment. For example, the bioactive agent may be selected to treat indications such as atherosclerosis, renal dialysis fistulae stenosis, or vascular graft stenosis. A coating of a graft material including a bioactive agent may be useful when performing procedures such as coronary artery angioplasty, renal artery angioplasty, or carotid artery surgery. Also for example, a bioactive agent such as a growth factor may be selected to promote ingrowth of tissue from the interior wall of a body vessel. An anti-angiogenic or antineoplastic bioactive agent such as paclitaxel, sirolimus or a rapamycin analog, such as zotarolimus, everolimus, biolimus, or a metalloproteinase inhibitor such as batimastaat may be included to mitigate or prevent undesired conditions in the vessel wall, such as restenosis. Many other types of bioactive agents also may be included in the solution. Just some examples of the large range of bioactive materials which can be applied to the medical device for treating targeted diseases or issues include but are not limited to: paclitaxel, heparin, azathioprine or azathioprine sodium; basiliximab; cyclosporin or cyclosporine (cyclosporin A); daclizumab (dacliximab); glatiramer or glatiramer acetate; muromonab-CD3; mycophenolate, mycophenolate mofetil (MMF), mycophenolate morpholinoethyl or mycophenolic acid; tacrolimus (FK506), anhydrous tacrolimus or tacrolimus monohydrate; sirolimus; interferon alfa-2a, recombinant (rIFN-A or IFLrA); antilymphocyte immunoglobulin (ALG), antithymocyte immunoglobulin (ATG), antilymphocyte serum, antithymocyte serum, lymphocytic antiserum or thymitic antiserum; brequinar or brequinar sodium; cyclophosphamide, cyclophosphamide monohydrate or anhydrous cyclophosphamide; dactinomycin, actinomycin C, actinomycin D or meractinomycin; daunorubicin, daunorubicin hydrochloride, daunomycin hydrochloride or rubidomycin hydrochloride; doxorubicin, doxorubicin hydrochloride, adriamycin or adriamycin hydrochloride; fluorouracil; gusperimus or gusperimus hydrochloride; inolimomab; leflunomide; mercaptopurine, mercaptopurine monohydrate, purinethiol or anhydrous mercaptopurine; methotrexate, methotrexate sodium, methotrexate disodium, alpha-methopterin or amethopterin; mustine, mustine hydrochloride, chlormethine hydrochloride, chlorethazine hydrochloride, mechlorethamine hydrochloride or nitrogen mustard (mustine); mizoribine; vinblastine, vinblastine sulfate or vincaleukoblastine sulphate; a pharmacologically or physiologically acceptable salt of any of the foregoing; or a pharmacologically or physiologically acceptable mixture of any two or more of the foregoing. These bioactive agents have effects known in the art including as thrombolytics, vasodilators, antihypertensive agents, antimicrobials or antibiotics, antimitotics, antiproliferatives, antisecretory agents, non-steroidal anti-inflammatory drugs, immunosuppressive agents, growth factors and growth factor antagonists, antitumor and/or chemotherapeutic agents, antipolymerases, antiviral agents, photodynamic therapy agents, antibody targeted therapy agents, prodrugs, sex hormones, free radical scavengers, antioxidants, biologic agents, radiotherapeutic agents, radiopaque agents and radiolabelled agents.
It is understood that any of the methods of use and treatment with the medical device described herein may include a medical device without a graft covering. The medical device 10 with the active anchor elements 20 may be used to reinforce the weakened and enlarged body vessel. In some examples, after implantation of the medical device with the active anchor elements, the implanted device may also have use in providing radial scaffolding for a secondary device to attach to. The implanted device may then be used to provide suitable anchorage for secondary endografts or other devices. Other body vessel, duct or pathway diseases or reshaping are possible.
With respect to an alternative embodiment of the medical device similar to that described above, but without a graft covering, the bare mesh stent of
A type 1 endoleak may be defined as an incomplete sealing of the landing zone of an endovascular device to the arterial wall in the EVAR. When a type 1 endoleak is present, the aneurysm sac may be continually filled with arterial blood flow and thereby systemic pressure in the aneurysm sac is not reduced. Significant pressure within the aneurysm sac increases the risk of sac rupture and therefore typically requires an immediate repair. An illustration of examples of different type 1 endoleaks is provided in
Current treatment options of type I endoleak include balloon molding, placement of extension cuffs and/or Palmaz stents. If there is a continual endoleak, then coil or glue embolization of the endoleak tract in the aneurysm sac may be performed and, typically as a last resort, open conversion may be practiced. However, while some current treatment options may have more success than others, the current treatment methods may lack precise control of the outcome and may fail prevent a future endoleak caused by enlargement of the aneurysm sac or by device migration. The contributing factors to a type 1 endoleak may include (1) challenging anatomy of the landing zone (e.g. short neck, tortuosity, large neck diameter, or thrombus), (2) device migration, as well as (3) subsequent sac enlargement after EVAR. However, multiple factors can complicate the determination of risk of endoleak development and restrict the patient population that would otherwise benefit from EVAR. A bare mesh stent 500, such as shown in
As shown in the
Referring to
The bare mesh stent delivery system may be constructed, and function, in substantially the same way as discussed for the delivery system of
A sequence of steps for inserting the bare mesh stent 500 into a previously installed AAA device 510 to repair a type 1 endoleak repair is shown in
Next, as shown in
As illustrated in
In another implementation, rather than waiting until after insertion of a standard AAA device and repairing any noted endoleaks by positioning a bare mesh stent 500 at an affected end of the AAA device, a multi-section bare mesh stent may be used to pre-condition an arterial lumen prior to even inserting an AAA device. In this manner, the regions of the lumen important to properly fit with the ends of the AAA device may be formed to a shape and condition more suitable to avoiding endoleak issues.
The success of an EVAR device is based in part upon its ability to maintain a proximal seal to the aortic wall to divert the arterial pressure from the aneurysm sac to the device during the lifetime of the patient with no need for re-intervention. The sealing of an EVAR device, such as an AAA stent graft, against the aortic wall relies on the geometry of seal interface and force interaction from the aortic wall and the device. Compromise at the sealing interface will result in type 1 endoleak and cause continual growth of aneurysm sac and the risk of aortic rupture may increase. In order to manage such risk, there are several geometric parameters; such as neck diameter, length and angulation of an aorta, that may be treated. One fairly common feature of aneurysm sac enlargement tends to be the shape and size of the sealing region in the aorta neck. Therefore an alternative way for treating and maintaining control of an aneurysm sac may include the ability to reshape the aorta, for example at the neck region, to maintain it at a smaller diameter and reduce the angulation prior to installation of an AAA device.
The multi-section bare mesh stent 600 of
As with the anchor elements 20, 504 described above, unlike conventional anchors, the branched anchor elements 604 of the multi-section bare mesh stent 600 can pierce a lumen wall at the deployment site through pressure applied with expandable balloon(s). Furthermore, these anchor elements retract the penetrated lumen wall by progressively coiling-up from the tip of the anchor wire upon exposure to induction heating via an induction device positioned outside the body. This “pierce-n-pull” ability allows reconstruction/reshaping of the challenging lumen geometry to a less-hostile vessel, thus potentially significantly expanding the patient population treatable by EVAR, as well as potentially reducing the risk of long term complications associated with sac enlargement and endotension.
As illustrated in
Once the anchor elements 604 have pierced the wall of the aorta, induction heating is applied and the wires will begin to close the gap between the aorta wall to the bare mesh stent through coiling as described previously. When the complete coiling of the anchor elements 604 has been achieved and the profile of the aorta wall to be re-shaped has been successfully covered by the mesh stent, the expanded balloon can be deflated and extracted, leaving the inherent radial retraction force of the multi-section bare mesh stent to reshape the aorta, resulting in diameter reduction and reduced angulation of previously highly angulated aorta. The installed mesh stent may also now act as preventative measure against future endoleaks, endotension and aneurysm sac enlargement. Additionally, the mesh stent can also act as anchoring platform for the subsequent endovascular device deployed at the site.
The above-embodiments have been focused on ways of using an artificial lumen into a damaged portion of an aorta. Typical T/EVAR devices work on a principal of diverting the arterial pressure from the aneurismal sac to the artificial lumen in the device constructed from tubular polyethylene terephthalate (PET) or polytetrafluoroethylene (PTFE) graft supported by a series of metallic stents. The fabric allows instant relief of arterial pressure and this feature is the key in preventing aneurismal sac growth and rupture as long as the sealing zone is maintained. The placement of the T/EVAR to divert the arterial pressure from the aneurismal region, however, can significantly disrupt the normal perfusion to the vital organs leading to ischemia. In order to work around this issue, current T/EVAR devices may be made with fenestrations and branches to allow perfusion of major and visceral arteries (i.e., subclavian, superior mesenteric, celiac and renal arteries). Nevertheless, these devices do not fully retain the normal perfusion of the smaller arteries that supplies blood to the spinal cord. While the reduced blood supply to the spinal cord is possible via subclavian and hypogastric arteries, a significant bypass of spinal arteries due to a large aneurysm repair can lead to spinal cord ischemia. Accordingly, another embodiment of a medical device able to repair an aneurism without the use of a graft, and thus may reduce or eliminate numerous ischemic complications typically associated with T/EVAR devices, is described herein.
As shown in
As illustrated in
In addition to providing secure anchorage and being able to reshape the aorta vessel wall as described with to prior embodiments, the centipede stent 700 is intended to be deployed in a stepwise manner to restore and reinforce the existing aortic tissue to carry the arterial pressure by the stent within the vessel. Illustrated in
As noted previously, the centipede stent is a series of self-expandable endoluminal stents connected at peaks by stretchable inter-stent locks 706 with anchor elements 704, such as the nitonol or other shape memory metal wires described previously, attached on the surface of the stent portions. The centipede stent 700 may be constructed of any desired length based on the amount of the aorta needing treatment. As with the prior stent graft and bare stent embodiments, the anchor elements 704 of the centipede stent 700 are initially folded down within a delivery device 730, as illustrated in
The centipede stent 700 may be deployed in an aorta in a step-wise manner. By implementing stepwise deployment, gradually drawing in the vessel wall in a manner akin to a zipper, even a highly tortuous aneurysm sac may be reshaped to a diameter largely defined by the inward radial force of the stent elements and their diameters without damaging the tissue.
Regional induction triggering the coiling and retraction of the exposed anchor elements 704 on the first portion is shown in
After the inductive heating is applied and the anchor elements 704 have coiled such that the aorta vessel wall W is held against the exposed portion of the stent 700, the balloon may be deflated and retracted so that the inward radial force of the portion of the stent draws in the aorta wall to a more desirable diameter. The process of
As described with respect to
Referring to
To clarify the use of and to hereby provide notice to the public, the phrases “at least one of <A>, <B>, . . . and <N>” or “at least one of <A>, <B>, <N>, or combinations thereof” or “<A>, <B>, . . . and/or <N>” are defined by the Applicant in the broadest sense, superseding any other implied definitions hereinbefore or hereinafter unless expressly asserted by the Applicant to the contrary, to mean one or more elements selected from the group comprising A, B, . . . and N. In other words, the phrases mean any combination of one or more of the elements A, B, . . . or N including any one element alone or the one element in combination with one or more of the other elements which may also include, in combination, additional elements not listed.
Embodiments have been disclosed of a single bare mesh device with anchor elements responsive to inductive heating that may be used to repair endoleaks in previously installed EVAR devices, such as AAA stents. Additional embodiments have been disclosed devices having multiple bare mesh stent portions linked by rigid material inter-stent locks that may be used to pre-shape a lumen, such as an arterial lumen, to allow subsequent insertion of an EVAR device and help prevent future endoleaks. Yet other embodiments have been shown of a stent device. referred to herein as a caterpillar stent, having multiple stent portions linked by flexible material inter-stent locks that, used in combination with a magnetically shielded delivery system, may be installed in a step-wise fashion to re-shape and strengthen an arterial lumen without the need for any graft material.
The method of deploying the caterpillar stent may include introducing the caterpillar stent into a body vessel at a treatment site in the magnetically shielded sheath, the caterpillar stent including a prosthesis body, and a plurality of anchor elements coupled along the prosthesis body. The magnetically shielded sheath may be retracted to only expose a first portion of the caterpillar stent. The process may next include radially expanding only the first portion of the caterpillar stent within the body vessel such that the anchor elements are in a first deployed configuration for piercing a wall of the body vessel at the treatment site. The anchor elements of the radially expanded first portion of the prosthesis may then be heated with an inductive heating source for moving the anchor elements from the first deployed configuration to a second deployed configuration where at least a portion of the anchor elements have an enlarged configuration along an abluminal side of the pierced body vessel such that the prosthesis and the pierced body vessel wall are moved relatively closer to one another. The magnetically shielded sheath may then be further retracted to expose a second portion of the prosthesis connected with the first portion. The second portion only is then radially expanded within the body vessel such that the anchor elements are in the first deployed configuration for piercing the wall of the body vessel at the treatment site. The anchor elements of the radially expanded second portion of the prosthesis are then heated with the inductive heating source for moving the anchor elements of the radially expanded second portion from the first deployed configuration to the second deployed configuration. The process is then repeated for as many times as necessary to install the remaining portions of the caterpillar stent.
The method may further include applying radial pressure with the radially expanded prosthesis to the first portion prior to the heating step of the first portion such that the anchor elements of the first portion pierce the body vessel wall. Additionally, the introducing step of the method may include introducing a balloon catheter with the caterpillar stent loaded on the balloon catheter into the body vessel at the treatment site, the balloon catheter having an inner cannula, and at least one inflatable balloon at a proximal end of the inner cannula, where the applying radial pressure step for the first portion of the caterpillar stent includes selectively expanding the at least one inflatable balloon to apply the radial pressure within the radially expanded first portion of the prosthesis so that the anchor elements pierce the body vessel wall. The heating step for the first portion of the caterpillar stent occurs while maintaining the selective expansion of at least one inflatable balloon within the caterpillar stent and while the second portion of the caterpillar stent remains shielded beneath the magnetically shielded sheath.
The at least one inflatable balloon may include a first balloon and a second balloon disposed in a longitudinal side-by-side relationship, where the applying radial pressure step includes selectively expanding at least one of the first and second balloons to apply the radial pressure with the radially expanded portion of the caterpillar stent such that the caterpillar stent is eccentrically positioned relative to the body vessel. Also, each of the anchor elements in the first deployed configuration may be disposed about an anchor axis, and in response to the heating step each of the anchor elements may maintain alignment substantially with the anchor axis to inhibit tearing of the pierced body tissue wall.
While various embodiments of the invention have been described, the invention is not to be restricted except in light of the attached claims and their equivalents. Moreover, the advantages described herein are not necessarily the only advantages of the invention and it is not necessarily expected that every embodiment of the invention will achieve all of the advantages described.
This application is a continuation-in-part of U.S. patent application Ser. No. 15/581,980 filed Apr. 28, 2017, pending, the entirety of which is hereby incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
Parent | 15581980 | Apr 2017 | US |
Child | 16054546 | US |