The present invention in general relates to medical devices and systems and in particular to percutaneous access device (PAD) or other implantable medical devices formed with chain mail.
Heart disease is one of the leading causes of death. Currently, medical science cannot reverse the damage done to the cardiac muscle by heart disease. One solution for such patients is a heart transplant. However, the number of cardiac patients in need of a heart transplant far exceeds the limited supply of donor hearts available.
The scarcity of human hearts available for transplant, as well as the logistics necessary to undertake heart transplant surgery, makes an implantable cardiac assist device a viable option for many heart patients. A blood pump can be surgically implanted in, or adjacent to the cardiovascular system to augment the pumping action of the heart. The blood pump is sometimes referred to as a mechanical auxiliary ventricle assist device, dynamic aortic patch, balloon pump, mechanical circulatory assist device, or a total mechanical heart. Alternatively, the blood pump can be inserted endovascularly.
Typically, the blood pump systems include a driveline that serves as a power and/or signal conduit between the blood pump internal to the patient and a controller/console external to the patient.
Often a percutaneous access device (PAD) can be surgically implanted in the body at the location in the skin where the driveline penetrates the skin to provide a through-the-skin coupling for connecting the supply tube to an extra-corporeal fluid pressure source. Alternatively, the fluid pressure source can be implanted wholly within the body, energized by electromagnetic means across intact skin, or energized by or chemical energy found within the body or some other means. Electrical leads from electrodes implanted in the myocardium are likewise brought out through the skin by means of the PAD. The aortic valve status or any cardiovascular parameter that is associated with this status can be employed to control the fluid pressure source to inflate and deflate the inflatable chamber in a predetermined synchronous relationship with the heart action.
The surface of the driveline, or of the optional PAD used in cardiac assist systems may have characteristics which promote the formation of a natural biologic seal between the skin and the device to form a barrier to microbial invasion into the body at the skin penetration site. Percutaneous access devices may also illustratively be used for other devices including peritoneal dialysis catheters, Steinman pin, Kirschner wires, and chronic indwelling venous access catheters that require skin penetration. More generally, medical appliances which are implanted so as to cross the skin surface and therefore violate the “barrier function” of the skin, may also illustratively be used for other medical purposes including peritoneal dialysis catheters and, chronic indwelling venous access catheters, neurologic prostheses, osseointegrated prostheses, drug pumps, and other treatments that require skin penetration.
A common problem associated with implantation of a PAD or other skin penetrating appliance is skin regeneration about the periphery of the appliance to form an immunoprotective seal against infection. New cell growth and maintenance is typically frustrated by the considerable mechanical forces exerted on the interfacial layer of cells. In order to facilitate skin regeneration about the exterior of the appliance, subject cells are often harvested and grown in culture onto appliance surfaces for several days prior to implantation in order to allow an interfacial cell layer to colonize appliance surfaces in advance of implantation. Unfortunately, cell culturing has met with limited acceptance owing to the need for a cell harvesting surgical procedure preceding the implantation procedure. Additionally, maintaining tissue culture integrity is also a complex and time-consuming task.
A related context in which cell growth is needed is wound healing, with DACRON® based random felt meshes have been used to promote cell regrowth in the vicinity of a wound, or to promote tissue anchorage by fibrous-scar-investment of a medical device crossing the skin surface. Such felts have uncontrolled pore sizes, some of which function as safe-haven microenviornments that harbor bacterial growth.
U.S. Pat. No. 7,704,225 to Kantrowitz solves many of these aforementioned problems by providing cell channeling contours, porous biodegradable polymers and the application of vacuum to promote cellular growth towards the surface the neck of a PAD. The facilitating of rapid cellular colonization of a PAD neck allows the subject to act as their own cell culture facility and as such affords more rapid stabilization of the PAD, and lower incidence of wound separation and infection.
The modular external interface 200 is secured and sealed to an outer layer of a patient's skin with a medical dressing. In a specific embodiment the medical dressing is a preform patterned and shaped to conform to the exterior of the modular external interface 200. In a specific embodiment the medical dressing preform may be in two halves (212214) that overlap. In a specific embodiment the medical dressing preform may be transparent. In a specific embodiment the medical dressing preform may be made of Tegaderm™ manufactured by Minnesota Mining and Manufacturing Company.
Despite the advances in PAD design and the securement of PAD to a subject's skin there continues to be a problem of disrupting the formation and maintaining of skin layers about the PAD with respect to flexible or pliable drivelines during the healing process. Infection at the site of PAD used with pliable and flexible drivelines continues to occur as the seal between the layers of skin and the bendable driveline tends to either not fully form or fails as the driveline flexes at the insertion site.
There is a continuing need for improved percutaneous access devices that minimize the disruptive forces to nascent layers of skin that are being formed during the healing process, as well as maintaining an infection preventive seal around flexible or pliable drivelines
A percutaneous access device (PAD) is provided that includes a chain mail collar formed from a plurality of intersecting ringlets formed of biocompatible materials, and a central aperture through the chain mail collar. The device may further include a sensor for measuring healing in vivo proximal to the chain mail collar. The plurality of intersecting ringlets may have a shape of planar circular, planar triangular, planar rectilinear, planar square, planar pentagonal, planar oval, planar hexagonal, three dimensionally kinked rectilinear, and three dimensionally kinked oval. The chain mail collar may be formed by three dimensional (3-D) printing.
A process is provided of repairing a hernia that includes inserting a chain mail sheet formed from a plurality of intersecting ringlets formed of biocompatible materials proximal to weakened or ruptured luminal area of a subject, and adhering the chain mail sheet as a reinforcement mesh across the weakened or ruptured luminal area. The chain mail sheet may be inserted laparoscopically and is collapsed for insertion into the patient and then unfurled at the weakened or ruptured luminal area. The process further includes creating a vacuum draw or hydrostatic draw through the chain mail sheet.
The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which like reference numerals refer to like parts throughout the several views, and wherein:
Embodiments of the invention provide percutaneous access devices (PAD) or other implantable medical devices formed with chain mail. The use of chain mail allows for a flexible PAD as used herein may include PAD used in cardiac assist systems that promote the formation of a natural biologic seal between the skin and the device to form a barrier to microbial invasion into the body. Percutaneous access devices may also illustratively be used for other devices including peritoneal dialysis catheters, Steinman pin, Kirschner wires, chronic indwelling venous access catheters that require skin penetration, and osseo-integrated percutaneous medical appliances.
Chain mail refers to sheets of material that are formed from ringlets linked together in a pattern. Unlike conventional chain mail that is only formed in two dimensional sheets, according to the present invention, chain mail is formed in elongated linear chains with occasional interlinks, two dimensional sheets, and in other configurations and combinations including three dimensional structures, pendant petals, elongated linear chains, combined fractal structures having a non-integer dimensionality intermediate between 1 and 3, and combinations thereof. Chain mail can also be formed of combinations of simpler structures to form higher-order structures.
A ringlet is readily formed in a variety of shapes besides the simple circular ringlet per
Ringlets are formed of a variety of biocompatible materials including those that are bio-retained as well as those that are biodegradable, and a combination thereof. Materials from which a ringlet are formed illustratively include titanium, alloys containing a majority by weight titanium, tungsten, and tantalum; stainless steel; polyurethane, fluorpolymers, perfluoropolymers, silicones, polylactides, biodegradable polymers, and non-biodegradable polymers. It is appreciated that a ringlet is readily provided with a surface coating or treatment. Surface coatings operative herein include any of the aforementioned polymeric materials from which ringlets are formed, antimicrobials, fibroblast adhesion promoters, fibroblast stimulation promoters, vascular growth factors, bioactive growth factors and a combination thereof. Surface treatments operative in the present invention include anodization of ringlets formed of metal, plasma surface roughening, chemical surface roughening, carbidization or anodization of ringlets formed of metal, and mechanical polishing. It is further appreciated that a facing layer of tiles can be added to thereto in a miniature form of that contemplated to protect spacecraft. https://newatlas.com/3d-print-space-fabric/49105. The facing tiles formed of any of the aforementioned substances and can be in the form of tiles, polymeric sheets, fabrics or combinations thereof.
In some inventive embodiments, chain mail of the present invention is formed by three dimensional printing. An exemplary processes of 3D printing with implant compatible metals is detailed in L. E. Murr et al. J. of Matls. Res.& Tech.; 2012, 1(1), 42-54; while such a process for biocompatible polymers is detailed in Q. Chen et al., ACS Appl. Mater. Interfaces 2017, 9(4), 4015-4023.
Embodiments of the inventive percutaneous access devices (PAD) or other implantable medical devices formed with chain mail may have ringlets formed of materials and metals suitable for medical use illustratively including titanium, tungsten, tantalum, or alloys in which any one of the aforementioned metals constitute the atomic percent majority of the alloy; and stainless steel. The individual ringlets may have diameters that are sized to favor attachment to the skin via fibroblast attachment. The additional layers of chain mail may be added to specific areas of a sheet of chain mail to provide additional reinforcement or to add three dimensional (3-D) features such as a lip that in some embodiments functions as an anchoring extension. The additional layers of chain mail may be joined to underlying layers of chain mail via entanglement of ringlets, spot welds, stitching, or adhesives. It is appreciated that 3-D printing machines may be used to form multidimensional shapes using chain mail patterns in the layers as a two-dimensional (2-D) sheet is extended to a 3-D sheet of chain mail. The chain mail may be treated with anti-microbial substances and substances that encourage fibroblast attachment and growth on the chain mail.
Embodiments of the chain mail may be made into collapsible forms that may then be inserted into a patient and then deployed or unfurled at a target site to minimize a required incision during a surgical procedure, such as through a laparoscopic or other minimally invasive medical procedure. Embodiments of chain mail mesh sheets may be used for hernia repairs as a reinforcement mesh in a weakened or ruptured area.
Referring now to the figures,
In some embodiments, a sensor 307 is provided either alone or in combination with a fiber 305. A sensor 307 illustratively including a thermocouple; a gas sensor such as oxygen, or sulfur; exudate biochemical such as electrolytes such as sodium, potassium, or chloride; small molecules such as urea, creatinine, fibrinogen, matrix metalloproteinases (MMPs); proteins such as tumour necrosis factor (TNFa) and C-reactive protein (CRP); and combinations thereof. The sensor 307 having leads extending external to the skin such as via a fiber 305 or monitored wirelessly.
An inventive chain mail collar is connected, in some inventive embodiments, to a vacuum source. A vacuum source may be any source operable for creating negative pressure in or around the device. A vacuum source illustratively includes a passive vacuum such as a vacuum tube or bottle, or an active vacuum source illustratively a mechanical pump, a syringe, or other vacuum source. A vacuum source optionally applies a continuous or intermittent negative pressure. The magnitude of the negative pressure is optionally adjustable, constant, or variable. In some embodiments an intermittent vacuum is used. Alternatively, a hydrodynamic draw agent is provided that draws fluid from the tissue surrounding along the chain mail ringlets or fibers woven therethrough. Without intending to be bound by a particular theory, capillary draw is believed to be operative in drawing exudate in a direction of the vacuum drawn to promote healing and stabilization of the chain mail collar. A hydrodynamic draw source illustratively includes a super absorbent polymer such as sodium polyacrylate, polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxymethylcellulose, polyvinyl alcohol copolymers, cross-linked polyethylene oxide, and starch grafted copolymer of polyacrylonitrile; high osmotic pressure compositions, such as water soluble salts; and capillary flow draw agents such as dry silica, or other dry hydrophilic powders such as cellulosic material.
It is increasingly common for catheters and percutaneous access such as peripherally inserted central catheters (PICC), skeletal guide wires, cardiac assist device lines, or other instruments to be kept in place for weeks or months. The increased time in which such devices are maintained across the skin increases the likelihood of instrument related infection. Another common implantable device that breaks the skin and may be a source of infection are blood pumps that may be surgically implanted in, or adjacent to the cardiovascular system to augment the pumping action of the heart. The blood pump is sometimes referred to as a mechanical auxiliary ventricle assist device, dynamic aortic patch, balloon pump, mechanical circulatory assist device, or a total mechanical heart. Alternatively, the blood pump can be inserted endovascularly. Typically, the blood pump systems include a driveline that serves as a power and/or signal conduit between the blood pump internal to the patient and a controller/console external to the patient. Additional external medical devices may illustratively include implantable pumps such as insulin pumps and colostomy bags. Such devices are well suited for use with an inventive chain mail collar 302 as shown in
For example,
As noted above, the chain mail collar 302 in some inventive embodiments is adhered to the driveline 220 with an adhesive. In a specific inventive embodiment, the chain mail collar 302 may be attached to the driveline 220 by sutures. In a specific embodiment the chain mail collar 302 may be locally heated to a temperature sufficient to melt an outer surface of the driveline 220 to the chain mail collar 302. In still other inventive embodiments as shown in
Patent documents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These documents and publications are incorporated herein by reference to the same extent as if each individual document or publication was specifically and individually incorporated herein by reference.
The foregoing description is illustrative of particular embodiments of the invention, but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the invention.
This application is a continuation-in-part of International Application No. PCT/US19/61423 filed 14 Nov. 2019, which in turn claims priority benefit of U.S. Provisional Application Ser. No. 62/767,048 filed 14 Nov. 2018 and 62/898,628 filed 11 Sep. 2019, and is also a continuation-in-part of International Application No. PCT/US20/60673 filed 16 Nov. 2020, which in turn claims priority benefit of U.S. Provisional Application Ser. No. 62/935,680 filed 15 Nov. 2019, the contents of the aforementioned priority documents are hereby incorporated by reference.
Number | Date | Country | |
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62898628 | Sep 2019 | US | |
62767048 | Nov 2018 | US | |
62935680 | Nov 2019 | US |
Number | Date | Country | |
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Parent | PCT/US2019/061423 | Nov 2019 | US |
Child | 17320607 | US | |
Parent | PCT/US2020/060673 | Nov 2020 | US |
Child | PCT/US2019/061423 | US |