Patent Application
20170196673
The present disclosure relates generally to implantable medical devices, and more specifically, to a medical device that contains at least one region that can be selectively degraded by electrolytic corrosion.
A variety of medical devices have been developed for implantation within an anatomy or body (e.g., a human body). Many such devices are implantable within a body lumen (e.g., the vasculature and/or gastrointestinal tract (“GI tract”) of a human body). For instance, devices like stents, grafts, and stent-grafts may be implanted within the vasculature and/or GI tract of a human body to reinforce, replace, and/or bridge a damaged, unhealthy, or otherwise diseased portion of a body lumen. These devices may thus, in certain instances, guide blood and/or other fluids through a lumen defined by a cylindrical interior surface. During implantation, it is often necessary to anchor such devices in place, so that they will not migrate away from a damaged or diseased portion of the anatomy they are intended to repair.
Once deployed to the desired position within a patient, the ongoing efficacy of implantable devices can often depend on their ability to remain in an approximately fixed position relative to the surrounding tissue. For example, an occlusion device implanted to occlude or close an aperture should maintain its proper position relative to the tissue surrounding the aperture, or it may fail to close the aperture. Similarly, a stent graft device deployed in the location of a stricture should remain in the location of the lumen stricture to create or enlarge an open passageway for fluid flow.
In addition, it may be desirable for the medical device to be removed once the intended therapy or treatment is completed. Removal of such devices may be difficult due to tissue growth into and around the medical device. Thus, there exists a need in the art for a medical device that can be used in intraluminal or transluminal applications for the fully intended term of therapy and which can be removed with minimal trauma to the surrounding tissue and to the patient and without invasive or endoscopic procedures.
One embodiment relates to an implantable device that has a cathode region, a sacrificial anode region, and an antenna region. The implantable device may include at least one predetermined failure region susceptible to electrolytic degradation. Electrolytic degradation of the anode region and/or the predetermined failure region transforms the implantable device from a first configuration to a second configuration. The electrolytic degradation is initiated by the formation of an electrolytic cell that is formed when the antenna region remotely receives energy from an external transmitter device. In one embodiment, selective electrolytic corrosion by the formation of an electrolytic cell may be used to adjust the medical device from a first configuration to a second configuration. As one example, electrolytic degradation may be used to adjust the diameter of an implanted medical device, such as, for example, an adjustable diameter stent. As another example, the first configuration may be an anchored configuration where the medical device is anchored to a lumen and the second configuration may be a non-anchored configuration. Once de-anchored from the lumen, the device may be non-invasively removed, such as by passage through the digestive tract.
A second embodiment relates to an implantable device that has a cathode region, a sacrificial anode region, and a piezoelectric receiver region. A bridge rectifier may be used to increase power transfer efficiency. Electrolytic degradation of the sacrificial anode region transforms the implantable device from a first configuration to a second configuration. Electrolytic degradation is initiated upon the formation of an electrolytic cell, which is formed when the piezoelectric receiver region receives acoustic energy from an external transmitter device and converts the acoustic energy to electrical energy. In one embodiment, selective electrolytic corrosion by the formation of an electrolytic cell may be used to adjust a medical device from a first configuration to a second configuration. As one example, electrolytic degradation may be used to adjust the diameter of an implanted medical device, such as, for example, an adjustable diameter stent. As another example, the first configuration may be an anchored configuration where the medical device is anchored to a lumen and the second configuration is a non-anchored configuration. Once de-anchored from the lumen, the device may be non-invasively removed, such as by passage through the digestive tract.
A third embodiment relates to a method for remotely reconfiguring a device from a first configuration to a second configuration by receiving electrical energy from an external transmitter device to form an electrolytic cell. The formation of the electrolytic cell causes electrolytic degradation of a sacrificial anode region in the device. The implantable device may include at least one predetermined failure region susceptible to electrolytic degradation. For example, a region may be made susceptible to electrolytic degradation by making it thinner than surrounding regions or by insulating surrounding regions and leaving the susceptible region uninsulated.
A fourth embodiment relates to an implantable device that includes a cathode region and a sacrificial anode region. An electrolytic cell is formed between the cathode region and the sacrificial anode region when an antenna region remotely receives energy from an external transmitter device. A rectification circuit may be positioned adjacent to the antenna region to convert the electrical energy to direct current voltage. The formation of the electrolytic cell induces electrochemical corrosion of the anode region, which transforms the device from a first configuration to a second configuration. In one embodiment, the implantable device has a first configuration as a vascular filter where emboli blocking elements are positioned in the blood stream, and a second configuration as a stent where the emboli blocking elements are removed from the bloodstream after embolic protection is no longer required.
A fifth embodiment relates to an implantable device that includes a cathode region and a sacrificial anode region. An electrolytic cell is formed between the cathode region and the sacrificial anode region when an antenna region remotely receives energy from an external transmitter device. A rectification circuit may be positioned remotely, e.g., adjacent to the antenna region, to convert the electrical energy to direct current voltage. The formation of the electrolytic cell induces electrochemical corrosion of the anode region, which transforms the device from a first configuration to a second configuration. In one embodiment, the implantable device has a first configuration as a tissue defect closure device, which effectively and securely closes a defect, such as an atrial septal defect or ventricular septal defect, and a second configuration where the structure of the defect closure device is compromised, thereby transforming the mechanical properties of the device from rigid (as implanted) to soft and conformable (e.g., after sufficient tissue ingrowth has occurred) to maintain the device in position. In this manner, the device may work acutely to close the defect, then, at the discretion of a clinician, for example, be transformed to a pliable, conformable, long-term implant that does not abrade or irritate the host tissue with which it is in contact
A sixth embodiment relates to an implantable device fabricated wholly or in part from a material, which would naturally dissolve in the body absent a current impressed upon it. The device may include at least one dissolvable region, an anode region, and an antenna region. The antenna region remotely receives energy from an external transmitter device. The energy is used to maintain the dissolvable region of the device at a negative voltage potential with respect to the anode region. When the medical device is no longer needed, the supply of energy is discontinued and corrosion begins to dissolve the dissolvable region(s). In at least one embodiment, the medical device completely dissolves. Alternatively, the medical device is dissolved to a point where it can be naturally expelled by the body.
A seventh embodiment relates to an implantable device that includes a cathode region and an antenna region. The frame of the device has an electrically conductive, corrosion resistant core and an electrochemically degradable outer surface. An electrolytic cell is formed between the cathode region and the frame (which acts as the anode of the electrolytic cell) when energy is remotely received by the antenna region from an external transmitter device. The formation of the electrolytic cell degrades the outer surface of the frame, thereby compromising the structural integrity of the frame. As a result, a structurally stiff frame or frame member may thereby be transformed from a rigid device into a flexible or conformable structural element.
The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments, and together with the description serve to explain the principles of the disclosure.
Persons skilled in the art will readily appreciate that various aspects of the present disclosure can be realized by any number of methods and apparatus configured to perform the intended functions. It should also be noted that the accompanying figures referred to herein are not necessarily drawn to scale, but may be exaggerated to illustrate various aspects of the present disclosure, and in that regard, the drawing figures should not be construed as limiting.
The present invention is directed to implantable medical devices that contain at least one region that is selectively degradable by electrolytic corrosion. The electrolytic corrosion is initiated by the formation of an electrolytic cell that can be activated wirelessly at a designated point in time. Additionally, the medical device can incorporate one or more section(s) or region(s) therein that are designed to be predisposed to structural failure. The medical device may contain a cathode region, an anode region that will undergo degradation, and an antenna region. Electrolytic degradation of the anode region may cause, for example, a de-anchoring of the medical device, a reconfiguration of the medical device from a first configuration to a second configuration, or it may precipitate the absorption of the medical device. Alternatively, electrolytic protection may be employed to preserve an implanted device until such a time that its corrosion and subsequent absorption is desired. It is to be appreciated that the terms electrolytic protection, cathodic protection, and impressed current cathodic protection as used herein refer to the application of a voltage potential to a structure in order to inhibit corrosion of the structure.
In one embodiment, selective electrolytic corrosion by the formation of an electrolytic cell may be used to adjust the medical device from a first configuration to a second configuration. As one example, electrolytic degradation may be used to adjust the diameter of an implanted medical device, such as, for example, an adjustable diameter stent. The stent may be any conventional tubular or radially expandable stent having a generally flexible frame and an opening extending therethrough. The frame of the stent may be formed of one or more elongate member (e.g., a wire) that has been helically wrapped into a tubular form. Additionally, the stent may be covered or partially covered with a cover material. It is to be appreciated that cover materials may be chosen and configured so as to confine and trap any degradation products produced during the degradation process. Stents described herein may be used in a wide variety of different anatomies, implant sites (e.g., body lumens, organs, cavities, and the like) and types of implementations.
Turning to
In the embodiment depicted in
When the stent 10 is energized, corrosion occurs over the uninsulated and/or exposed anode surfaces. Therefore, it is desirable to expose only the sections or regions in which degradation and mechanical failure are intended to occur. Limiting the area of the exposed anode region also serves to accelerate the degradation of the targeted, sacrificial region. In this manner energy wirelessly provided to the antenna (i.e., constraining member 12) from an external source creates an electrolytic cell and induces electrochemical corrosion at the exposed, sacrificial anode region 14. The antenna is activated remotely, and does need not to be in direct physical contact with the energy source.
Energy is provided until the sacrificial region 14 has corroded to an extent that the sacrificial region 14 breaks and releases the stent 10 from its constrained configuration to an expanded configuration. The degradation and subsequent release of the constraining member 12 permits the stent 10 to expand to its full (or substantially full) diameter (D) (e.g., second configuration) without the use of any invasive techniques. The fully expanded configuration of the stent 10 may anchor the medical device in a lumen. Alternatively, the expansion of the stent may cause anchors (not illustrated) affixed to the stent to engage with the lumen wall to anchor the stent therein. The expansion of the stent may be initiated in order to increase blood flow or to compensate for stenosis in the stent or lumen.
In another embodiment depicted in
In some embodiments, the frame 20 of a stent may act as the receiving antenna.
In another exemplary embodiment, the sacrificial anode region may act as a link that holds a scissor or accordion structure in a retracted or extended position. Turning to
In a further exemplary embodiment, the formation of an electrolytic cell may be used to de-anchor a medical device from a lumen.
The degradation of the narrowed or uninsulated sacrificial anode region 36 of the anchor wings 32 causes the anchor wings 32 to fail in that once the narrow region 36 is electrochemically degraded and breaks, the anchor wings 32 are no longer able to apply the anchoring spring force necessary to hold the medical device 30 in the lumen 34. As a result, the medical device 30 is de-anchored from the lumen 34. Such a de-anchoring of the medical device 30 permits the medical device 30 to be non-invasively removed, such as via passage through the digestive tract. It is to be appreciated that regions susceptible to electrolytic degradation may also be created by electrically insulating a positively charged section(s) of the circuit with the exception of the regions, which are intended to degrade. A combination of narrowing and selective insulation may be used to predispose section(s) of the anchor wings 32 to electrochemical degradation.
In yet another embodiment, electrolytic degradation may be used to transform a medical device having one purpose into a second medical device having a second purpose. As one non-limiting example, an embolic filter may be electrochemically degraded and transformed into a stent-graft in situ.
In another embodiment, a medical device may be rendered conformable through the electrochemical degradation of a portion of the medical device. One non-limiting embodiment is depicted generally in
The conductive, corrosion-resistant core facilitates an extensive electrolytic degradation of the outer surface as it will continue to maintain electrical conductivity of the device via the electrically conductive (corrosion-resistant) core, even after a section or sections of the outer surface have been completely eroded. In such an embodiment, the core may be thin, flexible, and able to maintain an electrical connection between sections of the device, but is not able to contribute significantly to the device's strength or stiffness. The outer material, in contrast, maintains the strength and stiffness of the device until the material is degraded.
Still referring to
A second, non-limiting example of rendering a medical device conformable is depicted generally in
The occluder 70 may be covered in whole or in part with a biocompatible material, such as, for example, expanded polytetrafluoroethylene (ePTFE). The occluder 70 may be implanted in a body, and, after a period of time, the occluder 70 may become ingrown and/or covered with tissue. After a sufficient ingrowth of tissue, the frame 74 of the occluder 70 is no longer needed, as the ingrown tissue will hold the occluder 70 and covering material in place. At any time, particularly after tissue ingrowth into the occluder 70, energy may be transmitted to the occluder frame 74 from a remote energy source to erode the thinned areas 72 and compromise the occluder frame 74. Compromising the frame 74 reduces the chance of long-term abrasion during the cardiac cycle. As shown in
In a further embodiment, a medical device may be formed of an electrochemically degrading material such that the entirety of the medical device is degraded or substantially degraded when an electrolytic cell is formed. For instance, the elements forming the medical device may be tapered and/or otherwise designed so that the degradation of the medical device proceeds in a predictable and orderly manner such that a complete dissolution of the medical device or a nearly complete dissolution of the medical device occurs. Any portion of the medical device that is not completely dissolved may be passed through the digestive tract. As described above, a corrosion-resistant component may be embedded or otherwise incorporated in the medical device to maintain electrical connection between disparate elements of the degrading structure until complete or sufficient dissolution of the target sections has been accomplished.
In yet another embodiment, a voltage may be maintained on a medical device in order to prevent its degradation until a time when the medical device is no longer needed. Once the medical device has served its purpose, the voltage potential is removed and the medical device begins degrading. In at least one embodiment, the medical device dissolves completely.
It is to be noted that although the inventions described above are with reference to specific medical devices (e.g., stent devices, occluders, and embolic filters), it is to be appreciated that any medical device that contains a cathode, an anode region, is capable of receiving a wireless transmission from an external transmitter device, and contains at least one region that may be subjected to electrolytic degradation may be used and is considered to be within the purview of the invention. The devices described herein are exemplary in nature and are not meant to be limiting.
The invention of this application has been described above both generically and with regard to specific embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments without departing from the scope of the disclosure. Thus, it is intended that the embodiments cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
| Number | Date | Country | |
|---|---|---|---|
| 62277713 | Jan 2016 | US |
