This application is a partial continuation of patent application 11/473,971 filed on 23/6/2006, and the application 11/473,971 is a partial continuation of patent application 10/804,993 filed on 19/3/2004.
[ background of the invention ]
Various intracardiac repair devices are widely used in various medical procedures. For example, some intravascular devices, such as catheters and guidewires, are commonly used to simply deliver a fluid or other medical device to a particular location within a patient's vasculature, such as an alternate coronary artery. In addition, more complex devices are often employed in the treatment of particular ailments, such as devices used to remove vascular emboli or treat septal defects and the like.
In some cases, it may be desirable to occlude a patient's blood vessel, such as to prevent blood flow through an artery into a tumor or other wound site. Currently, this is usually accomplished only by inserting coil springs, such as Ivalon pellets (a commercial name for vasoocclusive pellets) and short sections, at the desired location within the vessel. These "embolic agents" will accumulate in the vessel and often float downstream of the site of release prior to occluding the vessel. This process often limits its utility, in part, due to the inability to accurately place the embolic agent. These embolic agents are rarely used as intra-cardiac occlusion devices.
The physician may need to temporarily occlude the septal defect until the patient is sufficiently stable to undergo open heart surgery and use a balloon catheter similar to that disclosed in U.S. patent 4,836,204 to Landymore et al. When such a catheter is used, a deployable balloon is provided at the distal end of the catheter. When the catheter is guided to the desired site, the balloon is deployed by the fluid until it substantially fills the vessel and is contained therein. Resins such as acrylonitrile harden within the bladder and may be used to permanently fix the size and shape of the bladder. The balloon can then be detached from the catheter tip and left in place. If the balloon is not full, it will not be adequately contained in the septal defect and may rotate and loosen from the septal wall, thereby releasing into the blood flow from either the right or left ventricular chambers. Overfilling of the balloon, which may result in rupture of the balloon and release of resin into the patient's bloodstream, is also undesirable.
Representative examples have been proposed in the past using mechanical embolization devices, filters and traps, as disclosed in U.S. patent 3,874,388 to King et al (hereinafter the '388 patent), U.S. patent 5,334,217 to Das (hereinafter the' 217 patent), U.S. patent 4,917,089 to Sideris (hereinafter the '089 patent), and U.S. patent 5,108,420 to Marks (hereinafter the' 420 patent). The devices of the '388,' 217, '089, and' 420 patents are typically preloaded into an introducer or delivery catheter and are not generally loadable by the physician during the procedure. During deployment of these devices, it is difficult, if not impossible, to retrieve them back into the delivery catheter, thereby limiting the effectiveness of these devices.
Obviously, the size of these devices is inherently limited by the device structure and shape. When an occluding device is used, as in the above-mentioned '089,' 388, '217 or' 420 patents (tamponade heads occluding septal defects), the device is compressed and thus increases the chance of sloughing as the size of the defect increases. These devices must therefore have a large retention skirt on each side of the defect. The location of the septal defect often dictates the size of the retention skirt. In septal defects of the membranous type, it is difficult, if not impossible, to effectively fix the position of the '388,' 217, '089, or' 420 devices without at least partially occluding the aorta. As such, the manufacturing of these disclosed devices is quite expensive and time consuming. Accordingly, there is a need to provide a compact device that is resilient and retractable into a delivery system without increasing the overall thickness of the device. The desired device can also be manufactured with a relatively small retention skirt so that it can be placed in a membranous-type septal defect without occluding the aorta.
In the case of a ventricular septal defect, if the central diameter of the occluding component exerts excessive pressure on the septum, it may cause cardiac occlusion, and if the retention skirt is too large, it may interfere with the opening and closing of the aortic valve. A certain stiffness is required to keep the current devices in the anti-hypertensive position, which makes the devices more difficult to deliver. Thus, there is a need for a small, easily delivered device that can be shaped to fit in the retention but not block the aorta or aortic valve, and which conforms to the tissue adjacent the conduction path without excessive pressure.
In the case of PDA, a small device that can be loaded with a 4f (french) catheter could potentially treat premature PDA infants. Surgical treatment is currently used for these patients because the anatomical dimensions of the PDA make it unsuitable to block the PDA with a coil.
Likewise, the shapes of prior art devices (e.g., square, triangular, pentagonal, hexagonal, and octagonal) require a large contact area with corners extending to the free wall of the atrium. Each atrial contraction (about 10 million times per day), the inner wire in prior art devices such as that described in the Das' 217 patent is bent, which results in fatigue failure of the structure in about thirty percent of all cases. The sharp corners of these devices have resulted in a high percentage of heart perforations and have therefore exited the market. Furthermore, the aforementioned devices require 14-16F (French) introduction catheters and are therefore not likely to be used for the treatment of congenital heart defects in children.
It would therefore be advantageous to provide a reliable occluding device that is both easily deployed through a 4F-7F catheter and accurately placed in a vessel or organ. It is also desirable to provide a small device that is retrievable for deployment in an organ within a patient.
A reliable small-sized intracardiac occlusion device is described in us patent 5,846,261 to Kotula et al, which is useful for treating, for example, Ventricular Septal Defects (VSDs), atrial septal defects (hereinafter ASDs), and patent ductus arteriosus (hereinafter PDAs). When these intravascular devices are made of a resilient metal fabric, a plurality of resilient strands exhibiting memory characteristics may be provided, with the resilient material being made from a wire formed by braiding. The fabrics are then deformed into a shape substantially conforming to the molding surface of the molding assembly, and the fabrics in contact with the surface of the molding assembly are heat treated at an elevated temperature. The heat treatment time and temperature are selected to substantially place the fabric in its deformed state. Upon heat treatment, the fabric is removed from the contacting mold components and will substantially retain its shape in the deformed state. The fabric thus treated defines the deployed state of the medical device, and the fabric can be placed in a duct in the patient's body through a catheter.
Embodiments of the Kotula et al invention may provide medical devices with specific shapes, and medical devices made according to the invention may address the medical needs and surgical methods described above. The device has a deployed compact configuration and may include a female clip that gathers and retains the end of the woven metal fabric to prevent it from unraveling and that is attached to the end of a delivery device or guidewire so that the device may be restored after deployment. In use, the guide catheter is placed and advanced into the patient such that the distal end of the catheter is adjacent to the site to be treated to treat the physiological condition. A preselected medical device made according to the Kotula et al invention has a pre-set shape and is then collapsed by longitudinal stretching and inserted into the lumen of a catheter. The device is advanced through the catheter and extends from its distal end, and due to its memory characteristics, the device tends to return substantially to its deployed, relaxed state near the treatment site. The clamp is then released allowing the guide wire or delivery catheter to be released and withdrawn.
According to a first embodiment, a typical elongate medical device has a tubular middle portion and a pair of deployed diameter portions, one at either end of the middle portion. The length of the intermediate portion is similar to the wall in which the thickness of the defect to be occluded is formed. The center of at least one of the deployed diameter portions may be concentric with or offset from the center of the intermediate portion, thereby occluding various septal defects including ventricular septal defects of the membranous type while providing a retention skirt of sufficient size to reliably occlude an abnormal opening in the septum. As described above, the ends of each braid of the device are clamped together with a clamp. The clip can be recessed into the deployed diameter portion of the device, thereby reducing the overall length of the device and creating a small occlusion.
In another embodiment of the Kotula et al invention described in the' 261 patent, the medical device is generally bell-shaped, having an elongated body, a tapered first end, and a larger flange second end. The second end has a fabric disc oriented generally perpendicular to the axis of the conduit in which it is disposed. The clamps holding the ends of the braided strands together are recessed toward the center of the "bell" to provide a compact device having a reduced overall height dimension.
The device described in the' 261 patent to Kotula et al is capable of blocking abnormal openings in blood organs, depending on the weft (pick) size of the fabric, and also on the number of strands of wire used in the fabric. However, the practical limitation is exactly how many strands of wire can be braided. For example, if 72 spools are used on the weaving machine, the size of the weft yarn woven out would be such that it would have to be long enough to allow the formation of a full thrombus and the total occlusion of blood flow through the device. Even with the 144-spool, blood flow is not immediately occluded. If the size of the weft yarn is effectively halved by doubling the number of spools on the braiding machine to 288, blocking will occur in real time when the medical device is placed at an abnormal opening. However, such a knitting machine is not practical due to size and cost considerations.
As a method for reducing the time required to complete a total occlusion, the Kotula et al' 261 patent proposes the concept of filling a medical device with an occluding fiber or occluding fabric, such as a polyester fabric. Such occlusive fibrous materials or fabrics are typically sewn manually in the field, greatly increasing the manufacturing cost of the medical device. Perhaps more importantly, the incorporation of polyester fibers or fabrics within the device prevents the ability to reduce the effective diameter of the device by stretching prior to loading the device into the lumen of a delivery catheter. It should be appreciated that the delivery catheter can only be used with younger patients after it has been reduced in size.
Accordingly, there is a need for a method of forming a collapsible medical device for occluding an abnormal opening in a blood organ that provides rapid occlusion after delivery and placement and does not require the addition of an occluding fabric placed inside the medical device as in the prior art.
Another limitation of the bell-shaped occlusion device described in the Kotula et al' 261 patent is related to its use in occluding Patent Ductus Arteriosus (PDA). The diameter and length of this conduit between the pulmonary artery and the aorta is variable and is not always perpendicular to the connecting vessels. The design of the bell-shaped occlusion device is such that the edge at one end of the device is located on the side of the aorta where the pressure is higher, and can extend into the aorta when the conduit is not perpendicular to the aortic wall. The bell-shaped design also does not ideally accommodate changes in the length and path of the tubing and may cause the device to be partially extruded outside the PDA. Yet another limitation is that the device must be delivered from the more difficult to reach side of the PDA pulmonary artery because the arterial cannula size is larger than the femoral artery in younger patients. For infants, the design of the PDA occluding component requires a small profile through which the 4F catheter can be passed so that premature infants can be delivered intravenously, while premature infants weighing more than 1.5-2 kg are delivered by the arterial approach. The PDA closed vein approach has the advantage that infants weighing as little as 1 kg can be treated. The advantage of the arterial delivery method for slightly larger premature infants is that angiography and device implantation can be performed through the common entry point of the femoral artery.
There is also a need for an improved occlusion device (occluding component) for closing a PDA having: improved security of placement; improved degree of accommodation for diameter, length and pathway variations; minimal intrusion into the pulmonary and aortic flows; and it is easier to arrange from the aorta side via the femoral artery inlet, in addition to the pulmonary artery inlet described above.
In treating damage or disease to a heart valve, such as the left atrioventricular or aortic valve, surgical repair or replacement with tissue or a mechanical valve is often required. These valves typically have a structural cuff surrounding the valve on the bottom. The surgeon sutures tissue to the structural cuff adjacent the bottom of the valve with sutures to hold the valve in place. For a number of reasons, sutures may accidentally come loose from weakened tissue or the suture breaks or is undesirably sutured. In any event, this loosening of the connective tissue from the structural cuff of the valve creates interstitial holes (perivalvular leaks, PVL) along the structural cuff, resulting in valve leaks and valve dysfunction due to backflow of blood and a drop in blood pressure between the ventricle and the atrium. These open areas may be circular, oval or half-moon shaped and must be surgically or otherwise closed. There is currently no ideal method for sealing these leaks other than surgery. Physicians have attempted to install the device described in the' 261 patent to Kotula et al, but the device is not ideal for use with valvular leaks of varying sizes and shapes. In the approach of blocking the PVL through the percutaneous transluminal pathway, one of the most time consuming aspects is to position the blocking device in the hole along the cuff of the valve structure.
Since current devices are not easily handled, it is preferable to deliver the device over a guide wire, which can be more easily guided across the leak prior to placement of the device. Another approach is to set the device with an easy to handle tip cannula.
Thus, there is a further need for a method of percutaneously treating paravalvular leaks by employing an improved occlusion device that is easily advanced through a guide wire or easily manipulated sheath into the small catheter of a delivery system and that can readily accommodate the shape and size of the various leak conduits characteristic of such valve leak pathologies without interfering with the function of the valve leaflets.
The present invention provides a solution to the problems of the prior art, represented by the' 261 patent to Kotula et al, which is easy to manufacture.
[ detailed description ] embodiments
The present invention provides percutaneous, catheter-guided occlusion devices for occluding abnormal openings in a patient, such as Atrial Septal Defects (ASDs), Ventricular Septal Defects (VSDs), Patent Ductus Arteriosus (PDAs), and Patent Foramen Ovale (PFO), among others. And may be used to construct a flow restrictor or aneurysm bridge or other type of occluding component for placement in the vascular system. In the manufacture of the medical device by the method of the invention, a planar or tubular metal fabric is provided. Such flat and tubular fabrics are made up of a large number of strands of metal filaments having a predetermined mutual orientation between the filaments. The tubular fabric has strands that define two substantially parallel, generally helical sets, with one set of strands having an opposite "hand", i.e. direction of rotation, to the other. This tubular fabric is also known in the textile industry as tubular braid.
The pitch of the wire strands (i.e. the angle defined between a turn of wire and the axis of the fabric, pitch) and the weft of the fabric (i.e. the number of wires per inch spanned, pick) as well as other factors such as the number of wires used in the tubular fabric and their diameter are critical to determining the performance of the device. For example, the greater the pick and pitch of the fabric, and therefore the greater the density of the strands of wire in the fabric, the stiffer the device for a given wire diameter. The high density of wires also provides a device with a greater surface area of wire, which generally increases the tendency of the device to be used in a vessel to occlude the vessel. This thrombosis can be enhanced, for example, by coating with thrombolytic agents, or attenuated, for example, by coating with unstable antithrombotic compounds. When a tubular fabric is used to construct the device of the Kotula' 261 patent, a tubular fabric having a diameter of about 4mm, a draft of about 50 degrees, and a fill yarn of about 74 (per linear inch) may be suitable for use in fabricating a device capable of blocking an abnormal opening having an inner diameter of about 2mm to 4 mm. However, the blockage is not formed in real time.
Planar metal fabrics are the more common fabrics and may be shaped as planar woven layers, knitted layers, and the like. There are typically two sets of wires in a fabric, with one set of strands oriented at an angle relative to the other, e.g., generally perpendicular to each other (with a draft of about 45 degrees). As noted above, the weft yarns and pitch of the fabric (or, in the case of a knitted fabric, such as a plain or double knit, the pitch and pattern of the knit) can be selected to optimize the desired properties of the resulting medical device.
The wire strands of the planar or tubular metal fabric are preferably made of a so-called shape memory alloy. Such alloys tend to have a temperature that causes a phase change such that the material has a preferred configuration that can be fixed by heating the material above a particular transition temperature to cause a change in the phase of the material. When the alloy cools down, the alloy will "remember" its shape during the heat treatment and will tend to assume this configuration unless limited thereto.
Without any intentional limitation, suitable wire strand materials may be selected from the group consisting of: a cobalt-based low thermal expansion alloy known in the art as ELGELOY; nickel-based high temperature high strength "superalloys" under the name HASTELLOY, a trade name under the name haynes international corporation; nickel-based heat treatable alloys sold under the trade name INCOLOY by International Nickel corporation, and many different grades of stainless steel. An important factor in selecting a suitable wire strand material is that the wire maintains a suitable degree of deformation caused by the molding surface (described below) when subjected to a predetermined heat treatment.
In a preferred embodiment, the wire strands are made of a shape memory alloy NiTi (known as NiTinol, nickel titanium alloy), which is an approximately stoichiometric alloy of nickel and titanium, and may also include minor amounts of other metals to achieve the desired properties. The processing requirements and compositional variations of NiTi alloy compositions are well known in the art and therefore will not be discussed in detail herein. The use of the shape memory alloy NiTi in a guide wire, as discussed in U.S. patent nos. 5,067,489 (inventor Lind) and 4,991,602 (inventor Amplatz et al), is incorporated herein by reference. Such NiTi alloys are at least partially preferred because they are commercially available and the handling of such alloys is more known than other known shape memory alloys. NiTi alloys are also extremely elastic, and can be said to be "superelastic" or "pseudoelastic" (pseudoelastic). This resiliency allows the device of the present invention to return to its pre-set deployed configuration during use.
Rather than having a single woven layer, a medical device formed in accordance with the present invention suitably laminates multiple layers of appropriately sized tubular or planar metal fabric sheets relative to one another and is inserted into the same mold where the fabric layers are deformed to substantially conform to the shape of the interior cavity of the mold. The shape of the lumen may allow the plurality of metallic fabric layers to be substantially deformed into the desired shape of the medical device. The wire ends of the tubular or planar fabric layers should be fastened to prevent the metal fabric from unraveling. Clamps or welds, as described below, may be employed to secure the ends of the wire strands. The present invention is advantageous in that it can be manufactured by separately heat treating the inner and outer fabric layers and then inserting one or more inner layers into the outer layers.
It is further contemplated that the inner and outer woven layers may be heat set to different geometries and then assembled with one layer in another, or may be heat set together to different geometries. In this case, the weave pitch of one fabric may be selected to be different from that of the other fabric if the wire ends of all the layers are joined together at each end. In other words, the ends of the multi-layered wire are joined together at one end of the device only, while the other end has a separate layer end joint, one end joint floating at the device end relative to the other. This allows the braid pitch to be the same for all layers and accommodates the length changes that occur when two different shapes are compressed (axially stretched) for delivery. It is also contemplated that one layer may be attached to another layer at selected points in the middle of the device by, for example, stitching, rather than being connected together at the ends of multiple layers of braided wires. When different layers have different shapes and different compressed axis lengths, the shorter axis length end may be connected to one or both ends of the longer length of fabric by an elastic member. For further explanation, fig. 12a-12f will depict several embodiments having different shapes and connections.
In the case of a tubular fabric, a mold may be placed in the fabric cavity prior to insertion into the mold so as to further define the molding surface. If the ends of the tubular metal fabric have been secured by clamping or welding, the module may be inserted into the lumen by manually moving the strands of the braided layer apart and inserting the module into the lumen of the innermost layer of tubular fabric. By using such a module, the size and shape of the finished medical device can be controlled to a relatively precise degree, while ensuring that the fabric conforms to the interior cavity of the mold.
The module may alternatively be made of a material that allows the module to be broken or removed from the interior of the metal fabric. For example, the modules may be made of a material that is brittle and brittle. Once this material is heat treated to contact the mold cavity and the mold pieces, the mold pieces are broken into small pieces that can be easily removed from the metal fabric. For example, if the material is glass, the mold and metal fabric can be struck against a hard surface to break the glass. These glass fragments can then be removed from the metal fabric casing.
Alternatively, the modules may be made of a material that can be chemically dissolved or decomposed with a chemical agent that does not substantially affect the characteristics of the wire strands. For example, the module may be made of a plastic resin that is resistant to high temperatures but can be dissolved by a suitable organic solvent. In this case, the fabric and the mold conform to the shape of the mold cavity and the mold due to the heat treatment, and then the mold and the metal fabric may be immersed in the solvent. Once the mold is substantially dissolved, the metal fabric can be removed from the solvent.
Care is taken to ensure that the materials chosen to make the modules are capable of undergoing heat treatment until at least the multiple fabric layers set without losing their shape. For example, the mold may be made of a material having a melting point higher than the temperature required to shape the strands of metal filaments but lower than the melting point of the strands forming the metal fabric layer. The mold and the layers of metal fabric that ultimately make up the medical device are then heat treated to set the metal material and the temperature can be raised to substantially completely melt the molded component, thereby removing the mold from the metal fabric. Those skilled in the art will appreciate that the shape of the mold cavity and the molded components may be varied in order to produce the medical device having a predetermined size and shape.
It will be appreciated that a particular module of a particular shape may produce a particular shape and that other modules having different shaped configurations may be used if desired. If more complex shapes are required, the mould and die may include additional parts including cam arrangements, but if simpler shapes are to be made, fewer parts of the die are required. The number of parts and the shape of those parts in a given mold is almost entirely determined by the shape of the desired medical device that substantially conforms to the metal fabric.
For example, when the layers of the tubular fabric are in their relaxed configuration, the metal strands making up the tubular fabric have a first predetermined relative orientation with respect to each other. When the tubular fabric is compressed along its axis, the fabric layer tends to splay outwardly from its axis, conforming to the shape of the mould. Upon such deformation, the relative orientation of the metal strands of the metal braid will change. The outside and inside metal fabrics generally conform to the surface shape of the mold cavity when the mold is assembled. The medical device has a pre-adjusted deployed configuration and a collapsed configuration that allows the medical device to be passed through a catheter or other similar delivery device. The shape of the woven layer substantially determines the deployed configuration when deformed to substantially conform to the molding surface of the mold.
Once the tubular or planar metal braid is properly positioned within the preselected mold and the metal braid is substantially conformed to the molding surface of the mold cavity, the braid is subjected to a heating process while remaining in contact with the molding surface. Heat treating a metal fabric comprising a plurality of layers of metal wire strands substantially sets the shapes of the metal wire strands from which they are braided to reoriented relative positions when the braid conforms to the molding surface. When the medical device is removed from the mold, the braid can maintain the surface shape of the mold cavity, thereby defining the desired shape of the medical device. This heat treatment depends to a large extent on the material of which the metal wire strands of the metal braid are made, but the time and temperature of the heat treatment should be selected so as to substantially bring the fabric layer into their deformed state, i.e. with the metal wire strands therein in their reoriented relative configuration, and with the braid generally conforming to the molding surface.
After heat treatment, the device is removed from the molding surface in contact therewith and will substantially retain its shape in the deformed state. If a molded component is used, the molded component may be removed as described above.
The time and temperature of the heat treatment vary greatly depending on the material used to make the wire strand. As mentioned above, a preferred class of materials from which the wire strands are made are shape memory alloys, with NiTinol Nitinol being the most preferred. If NiTinol is used to make the braided wire strands, the wire strands tend to be very elastic when the metal is in its austenitic phase; such excellent elastic phase states are often considered to be superelastic or pseudoelastic phases. By heating NiTinol above a certain phase transition temperature, the crystalline structure of the NiTinol metal will tend to "set" the shape of the fabric layer and the associated configuration of the wire strands in the positions they were in when heat treated.
Suitable heat treatments to set the nitinol into the desired shape are well known in the art. For example, a helically coiled NiTinol coil may be used in many medical devices, such as coils made to attach generally around the distal end of a guide wire and other medical devices known in the art. The use of NiTinol in these devices is well known and will not be described herein in detail in relation to the heat treatment parameters of the preferred NiTinol fabrics of the present invention.
In short, although it is known to maintain the NiTinol fabric at 500-. The heat treatment time is longer at lower temperatures and shorter at higher temperatures. These parameters may be varied as needed to accommodate variations in the exact composition of the NiTinol, the preheating of the NiTinol, the desired NiTinol characteristics in the final product, and other factors known to those of ordinary skill in the art.
Heating NiTinol with the application of an electric current is also known in the art, except by means of convection heating or similar methods. In the present invention this can be achieved by, for example, attaching electrodes to the opposite ends of the metal braid. To achieve the desired heat treatment, resistance heating may heat the wire to the desired heat treatment temperature, thus eliminating the need to heat the entire die to the desired heat treatment temperature. The materials, modules and methods required for molding tubular or planar metal fabric medical devices are further described in U.S. patent nos. 5,725,552, 5,944,738 and 5,846,261, which are assigned to the same assignee as the present invention and the disclosures of which are incorporated herein by reference.
Once the device is formed having the preselected shape, the device can be used to treat a physiological condition in a patient. A medical device suitable for treating a disease is selected substantially in accordance with one of the embodiments described below. After selection of the appropriate medical device, a catheter or other delivery device can be placed in the patient's body duct, with the distal end of the delivery device positioned adjacent to the desired treatment, such as in close proximity to the shunt of the abnormal opening in the diseased tissue (or even within it).
The delivery device (not shown) may have any suitable shape, but desirably comprises an elongated flexible metal rod or hypotube (balloon expandable guide tube), or a wire braided polymer tube having a threaded distal end that engages a threaded hole formed in the clip of the medical device. The delivery device may be used to push the medical device through the lumen of the catheter/cannula for deployment in a conduit within the patient. The delivery device may still accommodate the medical device as it is deployed from the distal end of the catheter. Once the medical device is properly positioned at the shunt of the abnormal opening, the shaft of the delivery device may be rotated about its axis to release the medical device from the delivery device.
In one embodiment of the occluding component, the delivery catheter and catheter/sheath may receive a coaxial guidewire that slides through the device, end clamp and central lumen of the delivery catheter to assist in guiding the delivery device and outer catheter/sheath to the desired site. The guide wire may be independently delivered through the vasculature and across the target treatment site, or may extend partially to the distal end of the delivery device and catheter/cannula and be advanced with the delivery device and catheter/cannula while the guide wire is manipulated to guide the occluding component to the desired site. In another embodiment, a steerable catheter/sheath facilitates placement of the delivery device and occluding component.
If it is determined that the medical device is not properly positioned at the shunt, the surgical personnel can retract the device to reposition the device relative to the abnormal opening by attaching the medical device to the delivery device. A threaded clamp attached to the medical device allows the operator to control in a manner that causes the medical device to open at the distal end of the catheter. When the medical device leaves the catheter, it will tend to resiliently return to the preferred deployed shape, which is set upon heat treatment of the fabric. When the device springs back to this shape, it tends to react against the distal end of the catheter, effectively pushing itself forward over the tip of the catheter. This spring action can lead to incorrect positioning of the device if the position of the device within the conduit is critical, such as must be placed in a shunt between two vessels. Because the threaded clamp enables the operator to continue to hold the medical device during deployment, the elastic action of the instrument can be controlled by the operator to ensure proper placement during deployment.
The medical device may be collapsed to its reduced diameter configuration and inserted into the lumen of a catheter. The collapsed configuration of the device may be any shape suitable for easy passage through the catheter lumen and proper deployment outside the distal end of the catheter. For example, the ASD occluding device may have a relatively elongated collapsed configuration in which the device is elongated along its axis. This collapsed configuration is typically achieved simply by elongating the device along its axis, for example by grasping the clamp by hand and pulling it apart, which causes the expanded diameter portion of the device to collapse inwardly toward the axis of the device. The PDA occluding device may also be manipulated in the same manner to collapse the device into a collapsed configuration insertable into a catheter by applying tension along the axis of the device. In this regard, these devices resemble "chinese handcuffs" which contract in diameter under axial tension.
If the device is to be used to permanently occlude a conduit in a patient, the operator may simply withdraw the catheter and remove it from the patient. This leaves the medical device deployed in the patient's vascular system to occlude a vessel or other conduit in the patient. In some circumstances, the medical device may be connected to the delivery system in a manner that secures the device to the distal end of the delivery device. Prior to removal of the catheter in the system, it may be necessary to separate the medical device from the medical device in the delivery device and remove the catheter and delivery device.
While the device may spring back to its original deployed configuration, i.e., the shape prior to being collapsed for passage through the catheter, it should be understood that the device may not always return fully to that shape. For example. It may be desirable for the device to have a deployed configuration with a maximum outer diameter that is at least as large as, and preferably larger than, the inner diameter of the lumen of the abnormal opening in which the device is used. If such a device is deployed within a smaller lumen vessel or abnormal orifice, engagement with the lumen will restrict the device from fully returning to its deployed configuration. However, because the device engages the inner wall of the lumen to accommodate the device, the device may be properly deployed.
When the device is used in a patient, thrombi tend to accumulate on the surface of the wire. Because the multilayer structure of the present invention provides a higher density of wires and smaller flow channels between the wires, the total surface area and resistance to blood flow of the wires will increase, thereby increasing the thrombogenicity of the device and allowing it to occlude the vessel in which it is used relatively quickly. It is believed that an occluding device constructed with an outermost 4mm diameter tubular fabric having a strand diameter of about 0.004 inches, a fill yarn of about 40 degrees, a pitch of at least about 30 degrees, and an inner tubular fabric having a strand diameter of about 0.001 inches, a fill yarn, and a pitch that is the same provides sufficient surface area to substantially occlude an abnormal opening or vessel having an inner diameter of about 2-4mm in a very short period of time of less than 5 minutes. A third or fourth layer of concentrically disposed braid may be added if necessary to increase the occlusion speed of the device. In addition, coating the wires of the device with a thrombogenic coating aids in the rate of occlusion.
Referring now to the drawings, embodiments of the medical device of the present invention will be discussed next. Fig. 1-4 illustrate a first preferred embodiment of a medical device 10 of the present invention for compensating for an Atrial Septal Defect (ASD). Referring to fig. 1-4, the instrument 10 is greatly enlarged to show the layers that make up the device. The ASD device is in its relaxed, unstretched state with the two aligned disks 12 and 14 joined together by a short intermediate cylindrical portion 16 (fig. 3). The purpose of this is that the device 10 may also be well suited for occluding a patent foramen ovale (PFO for short) defect as is known in the art. Those skilled in the art will appreciate that devices of this configuration may also be suitable for closure of ductal tracts during ostial defect fontan's. ASD is a congenital abnormality of the atrial septum characterized by a loss of the atrial septum structure. Shunts may occur in the atrial septum that allow flow communication between the right atrium and the left atrium of the heart. In larger defects, with significant left-to-right shunting through the defect, the right atrium and right ventricle volume overload, this increased volume is ejected into the pulmonary vascular bed of low resistance.
Pulmonary vascular occlusive disease and pulmonary arterial hypertension (atrial hypertension) develop in adulthood. A two-hole ASD patient with significant shunting (as determined by a ratio of pulmonary to systemic blood flow greater than 1.5) is ideally subjected to surgery at 2-5 years of age or at a later time of diagnosis. With the advent of two-dimensional echocardiography and Doppler (Doppler) color flow mapping, the precise anatomical anatomy of the defect can be visualized. The size of the defect as determined by balloon measurements corresponds to the selected size of the ASD device 10 used.
The device 10, shown in its free or relaxed state in figures 1 and 2, is adapted for deployment in a shunt site including an ASD or PFO. For purposes of example, the above-mentioned' 261 patent to Kotula describes how to use the device 10 during ASD closure, and reference may be made thereto if further information is needed. Turning first to the structural features of the instrument 10, the ASD occluding component is sized proportionally to the site of the shunt to be occluded. In the relaxed orientation, the shape of the metal fabric is: the two disks 12 and 14 are axially aligned and connected together by a short cylindrical section 16. The length of the cylindrical section 16 when not stretched is preferably approximately the thickness of the atrial septum, which ranges between 3 and 5 mm. The proximal and distal disks 12, 14 preferably have an outer diameter sufficiently larger than the shunt site to prevent migration of the device. The proximal disc 14 has a relatively flat configuration, while the distal disc 12 is preferably cupped proximally and slightly overlaps the proximal disc 14. In this manner, the resilient action of the device 10 will cause the periphery 18 of the distal disc to substantially engage the side wall of the septum and, as such, the outer edge of the proximal disc 14 will substantially engage the opposite side wall of the septum. The perimeter 18 of the disc 12 and the perimeter of the disc 14 may interact to form a larger radius outer edge than shown in fig. 1 to relieve pressure on the tissue adjacent the device.
The device 10 of the present invention includes an outer woven layer 20, a first inner layer 22, and possibly an optional third or innermost layer 24, thereby significantly increasing the density of the fabric without unduly increasing the stiffness of the device or exhibiting the ability to reduce the outer diameter when stretched longitudinally. Multiple inner layers may be used, if desired.
The ends of the tubular metal fabric device 10 are welded or clamped together with clamps 26 to avoid fraying. The ends of all layers may be brought together and fastened with two clamps, one at each end or with separate clamps at each end of each layer. Of course these ends may be secured together by other methods known to those skilled in the art of choice. A clamp 26 that ties the multiple layers of metal strands together at one end also serves to connect the instrument to a delivery system. In the embodiment shown in fig. 1, the clamp 26 is generally cylindrical and has a recess (not shown) for receiving the end of the metal fabric to substantially prevent the wires making up the woven fabric from moving relative to each other. The clamp 26 also has a threaded bore 28. The threaded bore is adapted to receive and engage a threaded distal end of a delivery device, such as a push wire.
The ASD occlusion device 10 of this embodiment of the invention may advantageously be manufactured according to the method described above. The outer layer 20 of the device 10 is preferably made of NiTinol wire having a diameter of 0.004-0.008 inches, but may be made of smaller or larger diameter strands as well. The weaving of the wire mesh including the outer layer may be performed by using a Maypole weaving machine (braider) having 72 wire guides (wire carrier) with a shielding angle (shield angle) of about 64 degrees and 28 picks per inch. Braided layers 22 and 24 each comprise 144 strands of NiTinol wire having a diameter in the range of 0.001 inch to 0.002 inch, braided at the same pitch. The stiffness of the ASD device 100 may be increased or decreased by varying the wire size, shielding angle, weft ratio, and number of wire guides or heat treatment processes. One of ordinary skill in the art will appreciate from the foregoing discussion that the shape of the mold cavity must conform to the shape of the desired ASD device. Likewise, it should be understood that some desired configurations may require some portion of the lumen to be convex. Fig. 3 illustrates the ASD instrument 10 in a slightly longitudinally stretched condition. The distance separating the distal and proximal disks 12 and 14 is preferably equal to or slightly less than the length of the cylindrical section 16. The cup-shaped profile of each disc 12 and 14 ensures adequate contact between the outer edge of the respective disc 12 and 14 and the atrial septum. With proper placement, a new endocardial layer of endothelial cells forms on the occluding device 10, thereby reducing the chance of bacterial endocarditis and thromboembolism.
The distance separating the disks 12 and 14 of the occluding device 10 can be increased to adapt the occluding device to other vessels in the patient with the unique advantages of a vaso-occlusive device in use. The device 10 generally includes a tubular intermediate portion 16 and a pair of flared diameter portions 12 and 14. The flared diameter portions are generally located at either end of the tubular intermediate portion. The relative sizes of the tubular intermediate portion 16 and the flared diameter portions 12-14 can be varied as desired. The medical device may be used as a vaso-occlusive device to substantially prevent blood flow through a patient's blood vessel. When the device 10 is deployed within a patient's vessel, it is positioned within the vessel such that its longitudinal axis substantially coincides with the axis of the vessel segment into which it is inserted. It is desirable to use a dumbbell shape to limit the ability of the vasoocclusive device to rotate an angle relative to the axis of the vessel to ensure that it remains in substantially the same position as the surgical personnel place it in the vessel.
For relatively firm engagement with the vessel lumen, the maximum diameter of the deployed diameter portions 12-14 should be selected to be at least as large as, and preferably slightly larger than, the diameter of the vessel lumen in which the device is deployed. When deployed within a patient's vessel, the vasoocclusive device will engage the lumen at two spaced apart locations. It is desirable that the length of the device along its axis be longer than its maximum diameter, which will substantially prevent rotation of the vasoocclusive device 10 in the lumen through an angle about its axis, substantially preventing the device from moving in the blood flow through the vessel and tumbling along the vessel.
The relative dimensions of the generally tubular intermediate portion 16 and the deployed diameter portions 12-14 of the vasoocclusive device can be varied as desired for any particular application by appropriate selection of the mold used during the thermal treatment setting of the device. For example, the outer diameter of intermediate portion 16 may range between about 1/4 to about 1/3 of the maximum diameter of the deployed diameter portion, and the length of intermediate portion 16 may be about 20% to about 50% of the overall length of device 10. While these dimensions are appropriate if the device is used only to occlude a vessel wall vessel, it should be understood that these dimensions may be varied if the device is used in other applications, such as a ventricular septal defect occlusion (VSD).
The aspect ratio of the device 10 shown in this embodiment (i.e., the ratio of the length of the device to its maximum diameter or width) is desirably at least about 1.0, preferably in the range of about 1.0 to about 3.0, and a particularly preferred aspect ratio is about 2.0. Having a larger aspect ratio will tend to prevent the device 10 from rotating generally perpendicular to its axis, which is known as end-over-end roll. As long as the outer diameter of the deployed diameter portions 12-14 of the device 10 is large enough to allow the device to rest fairly firmly against the lumen of the conduit in which it is deployed, the device cannot roll over, which helps to keep the device properly deployed for positioning in the vasculature of the patient or other conduit within the patient. Alternatively, having the natural relaxed diameter of the deployed diameter portions 12-14 significantly larger than the lumen of the vessel in which the device is deployed should also be sufficient to wedge the device in place in the vessel without undue concern for the aspect ratio of the device.
Referring now to fig. 5-7, there is shown a device 100 suitable for occluding a Patent Ductus Arteriosus (PDA). PDA is in fact a disease in which two blood vessels: the aorta and the pulmonary arteries, which adjoin the heart, have a shunt site between their respective lumens. Blood can flow directly between these two vessels through the shunt site, resulting in heart failure and pulmonary vascular disease. The PDA device 100 has a generally bell-shaped body 102 and an outwardly flared forward end 104. The bell-shaped body 102 is adapted to be positioned within the aorta to help secure the body of the device in the shunt site. The size of the body 102 and end 104 may be varied during manufacture as needed to accommodate different sized shunt sites. For example, the body 102 generally has a diameter of about 10mm along its substantially elongated middle portion and a length of about 25mm along its axis. In such a medical device 100, the bottom of the body may flare generally radially outward to an outer diameter equal to the outer diameter of the front end 104, and the outer diameter of the front end 104 may be on the order of about 20mm in diameter.
The base 106 needs to flare relatively quickly outward to define a shoulder 108 that tapers radially outward from the body 102. When device 100 is deployed in a vessel, shoulder 108 will be in close proximity to the periphery of the lumen to be treated with high pressure. The front end 104 remains within the vessel and pushes the bottom of the body 102 open to ensure that the shoulder 108 engages the wall of the vessel to prevent the device from moving within the shunt site.
PDA blocking device 100 of an embodiment of the present invention can be advantageously manufactured in the manner described above by deforming multiple layers 110, 112 and 114 (fig. 7) of generally concentrically oriented tubular metallic fabric to conform to the molding surface of the mold, and heat treating the fabric layers to place the fabric layers in their deformed state. With continued reference to the larger enlarged view in fig. 7, the outer layer 110 includes a frame (frame) that defines the outer shape of the medical device 100. It is preferably made of 72 or 144 braided strands having a diameter in the range of about 0.003 to about 0.008 inches. The slope of the fabric may vary. Within this frame is a layer 112 which forms an outer jacket (outer liner). It may also prove advantageous to incorporate the third layer 114 as an inner liner. The jacket and liner may be braided using 144 strands of shape memory wire having a diameter of 0.001 to 0.002 inches. The slope of the weave in layers 112 and 114 may be the same. As mentioned above, the ends 116 and 118 of the fabric layer should be secured to prevent the fabric from loosening. In the preferred embodiment, at each end 116 and 118 of the tubular braid forming the occluding device 100, a clamp 120 is used to tie the respective ends of the wire strands together. Alternatively, the ends of the wire strands of the outer fabric layer may be secured using a different clamp than that used to secure the ends of each inner layer wire strand. It will be appreciated that other suitable fixing means may be attached to the ends in other ways, for example by welding, soldering, brazing, using a biocompatible adhesive material or in any other suitable way. One or both of the clamps 120 of the outer layer may include threaded holes 122 (not shown) for attaching the apparatus 100 to a delivery system. In the embodiment shown, the clamp 120 is generally cylindrical and has a crimped recess to receive the ends of the strands of wire to substantially prevent the wires from moving relative to each other.
When using raw NiTi fabric, which strands will tend to return to their unwoven configuration, fabric layers 110, 112 and 14 can be released fairly quickly unless the ends of the braid lengths cut to form the device are constrained relative to each other. The clamps 120 effectively prevent the layers of fabric from loosening at either end. Although soldering and brazing of NiTi alloys has proven to be rather difficult, the ends may be welded together, for example by spot welding with a laser welder. When cutting a fabric comprising a plurality of layers 110, 112 and 114 to the desired size, care should be taken to ensure that the fabric layers do not come loose. For example, in the case of a tubular fabric made of NiTi alloy, each of these strands will tend to return to their heat set configuration unless constrained. If the fabric is heat treated to set the strands in the fabric structure, they will tend to remain in the braided shape and only the ends will be worn. However, it may be more economical to form the fabric without heat treating the fabric, as the fabric would again be heat treated when forming the medical device.
Once the fabric is compressed to conform to the walls defining the interior of the mold, the fabric layer may be subjected to a heat treatment as described above. When the mold is reopened, the fabric will substantially retain its deformed, compressed configuration. The resulting device 100 may be collapsed, for example by pushing the clamps 120 away from each other in a substantially axial direction, which will tend to collapse the device 100 toward its axis. The collapsed device may then be coupled to a delivery device, such as an elongated flexible pusher wire, and passed through a delivery catheter for deployment at a predetermined location within the patient. The scheme for blocking the PDA using the resulting device is the same as that described in the Kotula' 261 patent and need not be repeated here.
Since the number of metal wire strands is significantly increased in the composite multilayer structure, the introduction of a sewn-in polyester material is no longer required to reduce the time required to establish a full occlusion of the PDA. This not only reduces the cost of manufacture, but also facilitates loading of the resulting device into a reduced size French delivery catheter. The reduced size of the French catheter means that younger patients can be treated, which has great benefits.
Figures 8-10 show various arrangements of vascular plugs. These plugs are ideally suited for the treatment of various arteriovenous malformations and hemangiomas. These plugs may also be used to block blood flow to a tumor or wound site. These plugs may also be used to block fluid flow through a portion of a body vessel in conjunction with treatment of other medical conditions.
Each of the embodiments shown in fig. 8-10 has a multi-layer woven structure 150, i.e., two or more layers of fabric. When the multi-layer braid is in a tubular shape, a pair of end clamps 152 and 154 are provided to prevent the multi-layer braid structure from loosening. It will be appreciated by those skilled in the art that if the fabric is bag-shaped, as opposed to having a tubular shape, only one end clamp is required.
The embodiment shown in fig. 8 has a cylindrical wall 155 with two end faces 156 and 158 at opposite ends of the wall. Generally, when the device is in the deployed configuration as shown in FIG. 8, the cylindrical wall abuts the vessel wall in which the device is deployed to remain in place. Two end faces 156 and 158 prevent fluid flow through the device.
In certain treatment conditions, it may be desirable to increase the number of end faces to improve the ability of the device to prevent fluid flow through the device. Figures 9 and 10 show how this can be achieved.
The device shown in fig. 9 also has a cylindrical wall 155, a proximal face 156 and a distal face 158. The embodiment of fig. 9 is further provided with an intermediate clamp 160 that clamps the intermediate portion of the multi-layer woven material. Thus, the cylindrical wall is divided into two sections 155a and 155b, and two further end faces 162 and 164 are formed. When the device of fig. 9 is deployed, the two segments 155a and 155b of the cylindrical wall 155 remain against the vessel wall to hold the device in place, and liquid must flow through the device across all of the end faces (i.e., end faces 156, 158, 162, and 164). Providing additional end surfaces 162 and 164 to reduce flow may result in faster clotting.
Fig. 10 shows the same basic structure as fig. 9, the main difference being that the application of the intermediate clamp 160 results in the two segments 155a and 155b being bulbous rather than cylindrical. The widest portions of the two segments 155a and 155b remain engaged with the vessel wall after deployment and hold the device in place. Although the end faces are curved, the structure still has four end faces (156, 158, 162, and 164) as opposed to the plane shown in fig. 9.
The intermediate clamp 160 may be made of any suitable material. The suture proved to be effective. The two end clamps 152 and 154 are preferably made of a radiopaque material to facilitate their visualization, for example, with a fluoroscope. The intermediate clamp can also be made of this material. In addition, adding more intermediate clamps may further increase the number of end faces. For example, if two intermediate clamps are used, a total of six end faces will be included. Two more end faces may be provided for each additional clamp.
Furthermore, when the multi-layer braided structure (or at least one layer thereof) is made of a superelastic or shape-memory material, it is possible to eliminate the intermediate clamp and use the mold instead to give the device a shape when the device is fully deployed and in its deployed, pre-adjusted configuration (e.g., the shape shown in FIG. 8). Of course, all of these embodiments, including the ones shown in fig. 8-10, can be deformed to a smaller cross-sectional size for delivery through a catheter.
Fig. 11a-11d show another modified embodiment for treating Patent Ductus Arteriosus (PDA). The dimensions given below relate to a typical range of dimensions for PDA baby tubes and are not intended as limitations. The PDA occlusion device 200 of this embodiment of the present invention may preferably be manufactured according to the method described above, i.e., deforming the multiple layers 210 and 212 of tubular metal fabric, generally concentrically oriented, to conform to the molding surface of the mold, and heat treating the braid to substantially place the braid in its deformed state. At least two of the braided layers in the device have the same molded shape. The damming device 200 has two disks 202, 204, one at each end, the outer portions of which extend from a diameter C to a diameter B, tapering toward the center of the device at an angle F in the range of 20-40 degrees, preferably 30 degrees. Each disk has a central portion 206 perpendicular to the central axis of the device 200 and extending outwardly to a diameter C, wherein C has a diameter in the range of 3-6 mm. Each disc is a mirror image of another disc having an outer diameter B in the range of 9-12 mm. The disk has a thin disk-like wall that is substantially slightly larger than the thickness of the two layers formed back-to-back, in the range of 0.005-0.010 inches, preferably 0.007 inches, or 0.014 inches of double wall (4 layers) thickness.
The device 200 comprises a central cylindrical portion 214 of diameter C in the range of 2-6 mm. The length of the cylindrical central section a is in the range of 2-8 mm. Between the disks at each end and the central cylindrical portion is a very small diameter E in the range of 1-2mm, preferably 1mm (or tightly bound wires in a group). The ratio of the large disk diameter B to the small diameter E is 6: 12.
This high ratio allows the tray to conform (pivot) to a wide range of wall angles relative to the axis of the PDA. This correspondence is shown in the 4 embodiments of fig. 11c-11 f. Fig. 11c shows the discs 202, 204 relatively parallel but at a substantial angle to the central section or device axis. The central section is elongated due to the smaller tubing than expected, and the elongation already includes the elongated tubing between the disks. In fig. 11d, the non-parallel disks conform to the wall of the aorta and the central section is again elongated to conform to the conduit between the disks. Figure 11e illustrates a device positioned within the heart valve perimeter VSD. The device in this case showed conformity with the thin film on the top of the defect and with the thicker septum at the bottom of the defect. The central section is fully expanded to shorten the distance between the disks to aid in the clamping force and filling the defect. Figure 11f shows a device positioned through a ventricular septal fissure. The central section 214 of the device is elongated to fill the slit and the disc conforms to the medial wall.
The ratios of diameters B to E and C to E as defined in fig. 11a allow the disks and central cylindrical portion to articulate at an angle to the axis of the device with diameter E and more readily conform to the variability of the vascular tract and tissue irregularities over the disk contact area. The diameter C is chosen to be slightly larger (10-20%) than the desired tubing to provide anchoring to the device. If the tube is longer than expected, the central portion may be stretched to accommodate the longer length. The disks are separated at the outermost point by a distance D in the range of 1-3mm, preferably 1 mm. In a section (C) perpendicular to the central axis of the device, the distance G between the inner surfaces of each disc is set in the range of 3-7mm, preferably 5 mm. The difference between the distances G and a provides variability in tubing length and consistency to irregular surfaces, as well as acting like a spring to apply a clamping force on each disk to the vessel to hold the device in place.
With continued reference to the larger magnification of FIG. 11a, the outer layer 210 includes a frame that defines the outer shape of the medical device 200. Preferably formed of 72 braided strands having a diameter of 0.001 to about 0.005 inch, preferably 0.0015 inch. The inclination of the weave is in the range 45-70 degrees, preferably 60 degrees. An inner layer 212 having the same shape as the outer layer 210 is within the frame. The inner layer is preferably braided using 144-strand shape memory wire having a diameter of about 0.001-0.003 inches, preferably 0.0015 inches. The weave slopes of the layers 210 and 212 are preferably the same, but may be different without departing from the scope of the present invention. As noted above, the ends 216 and 218 of each woven layer should be secured to prevent the fabric from unraveling. In a preferred embodiment, a clamp 220 made of platinum-iridium or stainless steel is used to tie the ends of the strands that form the two ends 216 and 218 of the tubular braid of the occluding device 220 together. The clamp 220 is preferably positioned outwardly from the disc as shown in fig. 11a, but may alternatively be recessed a fraction of the disc surface, however complete recess of the clamp requires grooves in the central portion end wall and the disc wall that can accommodate the length of the clamp. Alternatively, a different clamp may be used to secure the ends of the metal strands of the outer braid than the clamp securing the ends of the inner metal strands. It should be understood that other suitable fastening means may be attached to the tip in other manners, such as welding, soldering, brazing, using a biocompatible attachment material, or other suitable manners. One or both of the clamps 220 may include threaded holes 222 for connecting the apparatus 100 to a conveyor system (not shown). In the illustrated embodiment, the clamp 220 is generally cylindrical and has crimping grooves that receive the ends of the strands of wire so that the wires are substantially prevented from moving relative to each other.
When untreated NiTi fabric is used, its strands tend to return to their unwoven configuration, and the braided layers 210 and 212 may quickly unravel unless the ends of the braided layer length severed to form the device may be restrained relative to each other. The clips 220 are used to prevent the braid ends from unraveling. Although soldering or brazing NiTi alloys have proven to be rather difficult, the ends can be welded together by spot welding using, for example, a laser welder. When cutting the fabric comprising the multiple layers 210 and 212 to achieve the desired dimensions, care should be taken to ensure that the woven layers do not unravel. For example, in the case of a tubular fabric formed of a NiTi alloy, the individual strands tend to return to their heat-set configuration unless constrained. If the fabric is heat treated to set the braid configuration of the strands, they tend to maintain the braid shape and only the ends will fray. It may be more economical to simply form the fabric without heat treatment, however, because the fabric is again heat treated in forming the medical device.
In one embodiment of a blocking member (not shown) designed to be advanced within a guide wire, clamp 220 comprises two concentric rings, wherein the braided wire is constrained between the rings by using the methods described above or by swaging an outer ring over the wire and an inner ring. The inner ring in the clamp 220 serves to provide a central lumen for a sliding channel of guide wire. The tread clamp may use internal threads (inner ring) or external threads (outer ring), provided that a guide wire conduit is present.
Once the fabric is compressed into conformity with the walls defining the interior of the mould, the woven layer may be heat treated as described above. When the mold is reopened, the fabric generally maintains its compressed, deformed configuration. The resulting device 200 is contracted axially, for example, by forcing the clamps axially apart from each other. The collapsed device is then connected to a delivery device, such as an elongated flexible pusher wire, and passed through a delivery catheter for deployment at a predetermined site within the patient. The protocol for blocking the PDA using the resulting device is the same as that described in the Kotula' 261 patent, and need not be repeated here.
Fig. 12a-12f show another alternative embodiment. Various designs incorporate the advantageous features, size ranges, weave options, etc. of the previous embodiments, except as specifically noted. In fig. 12a, the disks 202 'and 204' are made of a single layer folded upon itself, with the central portion being a double layer. In this case, the slope of the inner layer must be increased relative to the outer layer so that both layers have the same length of contraction. This gives the designer flexibility to have disk portions with different characteristics relative to the central portion of the device. Fig. 12f shows an embodiment where the design is reversed, with the double layers in the disc portion back to back, as shown, and the single layer in the central portion, or with the layers in the central portion having different shapes.
Figure 12b shows a design variation where multiple layers of fabric have one end of the wire ends connected with a common clamp, but a free floating clamp is provided at the other end of the inner layer and separate from the clamps of the outer layer. In this design, one degree of freedom is to have different compressed braid lengths so that the pitch can be varied as desired. If desired, the inner layer may also follow the shape of the outer layer throughout with different slopes between the layers.
In the embodiment of fig. 12c, the inner layer 212 is suspended with stitched joints between the layers, and the end clamps of each layer are independent of each other.
In fig. 12d, the inner layer 212 has separate end clamps as in fig. 12c, but the layers are not joined by stitching, with the layers 210 and 212 having their end clamps joined by an elastic member such as one made of silicone rubber. Fig. 12e is similar to fig. 12d, except that the joint may be non-elastomeric, such as a suture or wire, and may optionally be attached over only one set of end clamps. All of the embodiments shown in fig. 12a-12f have a smaller diameter E than diameters B and C to maintain their connection advantages. Fig. 11a defines diameters A, B, C and E. As shown in fig. 12a-12f, it is contemplated that various optional features may be combined herein in any desired manner for any of the embodiments described.
Figures 13a-13f illustrate various embodiments for treating paravalvular leakage (PVL). Figure 13a shows the suturing of the artificial mitral valve 232 into the patient. The three striped line regions 234, 236 and 238 along the valve cuff represent open areas where tissue is pulled from the cuff due to weaker tissue or damaged or loosened sutures. These open areas short-circuit the valve blood flow and lead to cardiac dysfunction and hypotension. As shown in fig. 13a-13f, the present invention is designed here to close/block these PVLs.
The PVL damming device 100 of this embodiment of the present invention may advantageously be manufactured according to the method described above, i.e. by deforming a plurality of layers 310, 312 of generally concentrically oriented tubular metal fabric to conform to the molding surface of the mold, and heat treating the braid to set it substantially in its deformed state. Referring next to the larger enlarged view of fig. 13b-I, outer layer 310 includes a frame that defines the outer shape of medical device 300. Preferably 144-braid strands having a diameter in the range of 0.0015 to 0.0035 inches, preferably 0.002 inches. The slope of the weave may be in the range 45-70 degrees, preferably 60 degrees. The inner layer 312 is located within the frame. The addition of a third layer 314 (not shown) as the innermost layer has proven effective. The inner layer may be braided with 144 strands of shape memory alloy wire having a diameter of 0.001-0.002 inches, preferably 0.0015 inches. The weave slopes of layers 310 and 312 are preferably the same. As noted above, the ends 316 and 318 of the braid should be secured to prevent unraveling of the braid. In the preferred embodiment, a clamp 320 is used to tie the ends of the wire strands together at each end 316 and 318 of the tubular braid forming the occluding device 300. Alternatively, the jig for fixing the distal ends of the metal strands of the outer braid is different from the jig for fixing the distal ends of the respective inner-layer metal strands. It should be understood that other suitable fastening means may be used to attach the ends in other ways, such as welding, soldering, brazing, using a biocompatible attachment material, or other suitable means. One or both of the clamps 320 of the outer layer may include threaded holes 322 for connecting the device 300 to a transfer system (not shown). In the illustrated embodiment, the clamp 320 is generally cylindrical and has crimping grooves that receive the ends of the strands of wire so that the wires are substantially prevented from moving relative to each other.
When untreated NiTi fabric is used, its strands tend to return to their unwoven configuration, and the braided layers 310 and 312 may quickly unravel unless the ends of the braided layer length severed to form the device may be restrained relative to each other. The clips 320 are used to prevent the ends of the braid from loosening. Although soldering or brazing NiTi alloys have proven to be rather difficult, the ends can be welded together by spot welding using, for example, a laser welder. When cutting the fabric comprising the multiple layers 310 and 312 to achieve the desired dimensions, care should be taken to ensure that the woven layers do not unravel. For example, in the case of a tubular fabric formed of a NiTi alloy, the individual strands tend to return to their heat-set configuration unless constrained. If the fabric is heat treated to set the braid configuration of the strands, they tend to maintain the braid shape and only the ends will fray. It may be more economical to simply form the fabric without heat treatment, however, because the fabric is again heat treated to form the medical device.
Because PVL openings come in a variety of shapes, it is expected that many sizes and shapes of obstruction means may be required to close these weep holes. It is also important to safely position the stopper to prevent biasing of the device or formation of a plug. As shown in fig. 13b-I, the device 300 is formed from two layers of identical shape. Fig. 13b-II are plan views of the device 300, while fig. 13b-III are end views thereof. This particular design is intended to block an opening that is somewhat oblong in shape. If desired, radiopaque markers 330 can be placed on either the narrow or wide sides of the elongated shape to aid the physician in positioning the device. These markers may be radiopaque platinum or iridium markers attached to the fabric in a manner that does not interfere with the fabric's contraction or self-expansion. An oblong shape may conform to a more circular or longer shape because of the small diameter of the wire. Fig. 13c shows a crescent-shaped blocking element 324, and fig. 13d shows a circular blocking element 326. In figure 13e, one edge of the device interface with the cuff 240 is shaped to fit the shape of the cuff, while the other edge of the device interface with the tissue 242 has a shape that is more adapted to the thickness of the tissue at the interface. For illustrative purposes, figure 13b shows the dimensions of oblong blocking members, which are similar to other shapes of applications. All dimensions are in millimeters (mm), i.e., a-6, B-2, C-10, D-6, E-6, F-9, G-7, H-2.
Figure 13f shows a preferred clamp 320 for the device 300, intended to be compatible with guidewire delivery of the occluding component. In this design, the clamp 320 must have a central channel 328 through which the guide wire can slide. Thus, the clamp 320 can be made with an inner ring 330 having an inner diameter (about 0.002-0.004 inches) slightly larger than the diameter of the guide wire. The clamp also has an outer ring 332 large enough to accommodate the ends of the braided wire between the two rings. The outer ring may be forged to press the outer ring against the wires and the inner ring, or the wire ends and rings may be joined by welding, brazing, soldering or bonding or other known methods. At least one of the clamps is threaded on the outside of the outer ring or the inside of the inner ring of the clamp. If internal threads are used, the inner ring must be enlarged to accommodate the externally threaded delivery device, which has an internal cavity sized to guide the wire through the threaded fixture.
A guidewire delivery system is particularly useful in the delivery of PVL occlusive members. One of the most difficult aspects in this situation is to deliver the device through the defect near the valve cuff. Due to the turbulent flow of blood within the valve region, it is preferable to have a small surface and steerable guide wire first pass through the defect and then advance the delivery device and catheter over the guide wire. Alternatively, a guide wire may be provided through the catheter and delivery device and to guide the tubing of the system through the vasculature. In accessing the valve defect, the guide wire may be independently maneuvered through the defect, and the catheter and delivery device are then advanced over the guide wire.
A method of treating a peripheral leak of a valve may comprise the steps of: (1) advancing a guide wire through the vasculature in the body and across the valve orifice; (2) advancing a catheter containing an occluding component connected to a delivery device over a guide wire until the distal end of the catheter crosses the valve orifice; (3) deploying the distal portion (distal to lumbar) of the occluding component by manipulating the delivery device to extend the distal portion of the occluding component out of the distal end of the catheter, causing the distal portion to self-deploy to its predetermined shape; (4) drawing the catheter and delivery device together until the deployed portion of the occluding component contacts tissue adjacent one side of the opening; (5) withdrawing the proximal catheter relative to the delivery device to expose the remaining proximal portion of the occluding component while allowing the delivery device to be pushed distally as the occluding component self-deploys and contacts tissue on the other side of the proximal opening; (6) disconnecting the delivery device from the occluding component once the device is properly positioned to occlude the opening; and (7) removing the delivery device and catheter from the body.
Another method of treating a peripheral leak of a valve is similar to that described above, but includes the steps of: a guide wire is advanced through the vasculature by a catheter of a predetermined shape or manoeuvrability to facilitate passage of the conduit through the opening of the valve peripheral leak. Optional additional steps include: the catheter is withdrawn after crossing the side leakage opening and before delivery of the occluding component.
Another embodiment of the occluding component is a variation of the device shown in figures 12a-12f and the occluding device 400 shown in figures 14a-14c is constructed of a flexible and conformable outer fabric 410 that encloses a space 430 of the desired predetermined shape with two or more side-by-side braided tubular members 412a, b, c that share a braided wire end fitting at least at one end. As shown in fig. 14b and 14c, the plurality of fabrics need not be concentrically arranged. This arrangement moves medial braids 412 relative to one another to fill the available space of unknown size and shape, such as an oblong, crescent, or oval lumen shape. This is accomplished by selecting a heat-set fabric 412 having a diameter large enough to exert pressure on the outer tubular fabric, forcing it against the wall of the lumen in which the device is installed. To share the wire end clamps, the inner tubular fabric walls must be forced against each other at the ends and formed into a crescent to fit in a looped fashion over the wire end clamps on clamp 420 as shown in FIG. 14 a. The proximal clamp 420 on the wire end 418 constitutes a suture (not shown) that is attached to the delivery catheter. The proximal clamp 420 may or may not clamp the inner fabric end closest to the wire end. Preferably, the clamp 420 is attached to the proximal ends of the wires of the fabric 412 by a tether or elastic member so that the length of the fabric changes based on the change in shape of the device 400 in the lumen. The outer fabric of this embodiment may be a NiTinol 144 strand braided wire having a diameter of between 0.001 and 0.002 inches. The inner side of the fabric can be woven by using Nitinol wire with the diameter of 0.001-0.003 inch in a 72 or 36-ply method. An alternative method of delivery over a guide wire is practiced by wire end clamp 420, the double loop design described above.
In another embodiment 500 shown in fig. 15, outer fabric 510 is pre-shaped into a shape 530 defining a specific volume. A smaller diameter, pre-beaded tubular fabric 512 is contained within the outer fabric and shares a common outer fabric wire distal clamp coaxially. The inner smaller fabric 512 is much longer than the outer fabric 510 and when the fabric 512 is used to completely fill the volume shape, it is designed to meander into the outer fabric's volume-defining shape 530 and help conform the outer fabric to the shape of the lumen in which it is located. The distal wire end clamp 520 on the wire end 516 is preferably a two-part clamp with an inner and outer ring that clamps the braided wire between the rings. The proximal braided wire end clip 522 is of similar construction, but the outer ring is threaded to mate with threads on the delivery catheter 540 for selectively connecting the device to the delivery catheter. In this embodiment, a portion of the inner fabric remains within the delivery catheter when the outer fabric is fully deployed. To enable balanced delivery of the inner tubular fabric 512 into the volume 530, the push wire 528 within the delivery catheter 540 acts as a proximal wire end clamp 523 against the fabric 512 to push the fabric completely out of the delivery catheter. Push wire 528 may optionally have a threaded end to engage the threads of wire end clamp 523. The delivery catheter 540 may be advanced through the cannula to the treatment site. The high density of wires in volume 530 helps to quickly stop bleeding while maintaining a low profile during delivery. The spherical body of the bead chain is inserted into the aforementioned volume with the spherical body resting against the spherical body and then against the outer fabric, and thereby loads the surface of the outer fabric against the lumen wall to be blocked. For this embodiment, the outer fabric should be soft and conformable. The most suitable is 144 strands of Nitinol wire with a diameter of 0.001-0.002 inches. The inner fabric can be woven with Nitinol wire of 0.001-0.003 inch diameter in 72 or 36 ply. The outer and inner fabrics may be heat treated to set the desired volumetric shape and the desired bead chain shape as described above. Wire end clamps 520 and 523 can be in a double loop configuration, as described in another embodiment previously described, to configure the device for delivery over a guidewire.
The method of occluding a body lumen comprises the steps of: (1) providing an occluding component comprising at least a first self-expandable braided tubular layer defining a preset volume shape, and a second braided component longer than the first braided component in a contracted delivery configuration, said second braided component being coaxially attached at one end to an end of the first braided component and having a repeating preset volume, said preset volume occupying a shape substantially less than the predetermined shape of the first braided component, thereby enabling both the first and second braided components to be contracted and elongated to a smaller profile for delivery through a catheter and having a self-expandable preset volume for occupying an occluding space in a body lumen; (2) advancing the distal end of the delivery catheter containing the occluding component and the delivery device to the body lumen; (3) advancing the distal end of the occluding component out of the catheter causing the first braided layer of the occluding component to self-deploy within the lumen; advancing the distal end of the second braiding element within the volume occupied by the first braiding element until the entire self-expanding second braiding element is contained within said volume; (4) disconnecting the transfer device from the stopper; (5) the catheter and delivery device are removed from the body. An optional additional step of the above method is to deliver the occluding component, delivery device and catheter over the guidewire and remove the guidewire from the lumen before the first braided layer is self-deployed.
In another implementation, shown in figures 16a-16d, primarily for ventricular septal defects VSDs, the central diameter of the device may be relaxed in its flattened or inverted portion around its circumference to relieve pressure on the cardiac conduction bundle of his on the septal muscle portion to prevent cardiac block (figure 16 a). In addition, the device has only one occluding flange 600 (right ventricle) with a small diameter E, and the flange 602 at the opposite end (left ventricle) can be relaxed in diameter to prevent interference with the aortic valve. It is expected that a single occluding flange 600 will reduce the pressure of the conducting bundle of hessian, helping to prevent heart block, and that the lack of occlusion on the left ventricular side will better prevent the device from shifting due to elevated arterial blood pressure (fig. 16b and 16 c). Another embodiment to widen the diameter of the lv flange 602 to prevent interference with the aortic valve is to move the lv flange off axis to the center of the device so that the flange is moved off the valve as shown in fig. 16 d. A further variant is also envisaged in which the engagement of the flanges is eliminated, as shown in figure 16 d.
Although the PDA is shown in size, it is contemplated that the shape or variations of this device may be used in other occlusion applications, such as ASD, VSD, PFO or other similar abnormalities. The central portion may alternatively have a barrel-shaped, spherical or cylindrical outer surface with straight or tapered end walls. The central portion may be bellows-shaped to further accommodate variations in the length of the conduit, may be biconic with a center point at the maximum diameter, or any other shape desired. Similarly, the disks need not be inwardly angled, but this is preferred. The disks are preformed in a non-parallel manner and one disk may be of a different size than the other. While two layers are preferred, it is also contemplated that additional layers (3, 4 or more) may be used to fabricate the device. Likewise, the layers may have the same number of weft yarns and the same wire diameter, or may be varied in any order and manner to suit a particular application. In the preferred embodiment, the occlusion is relatively quick and small compared to the prior art, with improved retention and improved consistency due to the small pore size and large surface area created by the large number of wires in the multilayer, to accommodate various vascular conduits with minimal interference with the natural blood flow. The reduced profile of the device is small enough to allow delivery of the device through a 4f (french) catheter or cannula. The device 200 may also be symmetrical so that it can be delivered by a catheter from the pulmonary or aortic side, as selected by the physician. The venous closure PDA method has the advantage that infants weighing as little as 1 kg can be treated. An advantage of arterial delivery methods for slightly larger premature infants is that angiography and device implantation can be performed through the common entry point of the femoral artery.
By significantly increasing the number of metal strands in the composite multilayer structure, the need to incorporate a sewn-in polyester material is eliminated, thereby reducing the total time required to occlude PDA, VSD, ASD, PFO, PVL, or other vascular sites. This not only reduces the cost of manufacture, but also facilitates loading of the resulting occluding device into a reduced French size delivery catheter. The smaller size of the French delivery catheter means the ability to treat smaller vessels, which is a major advantage. The occluding components provided by the present invention are also more flexible, easily tracked, and more adaptable to occlusion of various defect geometries, while having improved gripping and reduced invasion into either defect side of the vasculature. Tracking over a guide wire provides delivery options for difficult to reach anatomical sites. Because of the symmetry of the device, some embodiments may be delivered from either the ventricular side or the atrial side of the defect.
The present invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments as required. However, it should be understood that the invention can be carried out by a variety of different devices and that various changes can be made without departing from the scope of the invention. For example, the selection of one embodiment can be readily applied to other embodiments. While many of the embodiments are shown as being fabricated with two layers of fabric, more layers may be added in any of the embodiments without departing from the scope of the invention if desired for a particular application.