DESC:ATRIAL SEPTAL OCCLUDER DEVICE
TECHNICAL FIELD
[0001] The present invention generally relates to intravascular devices for treating certain medical conditions and, more particularly, relates to intravascular occlusion devices for treating Atrial Septal Defects (ASD) and other related cardiovascular defects treatment. The devices made in accordance with the invention are particularly well suited for delivery through a catheter or the like to a remote location in a patient's vascular system or in analogous vessels within a patient's body. The invention relates to a Atrial Septal Occluder Device with a middle segment comprising of four discs.
BACKGROUND OF THE INVENTION
[0002] A wide variety of intravascular devices are used in various medical procedures. Certain intravascular devices, such as catheters and guide wires, are generally used simply to deliver fluids or other medical devices to specific locations within a patient's body, such as a selective site within the vascular system. Other, frequently more complex, devices are used in treating specific conditions, such as devices used in removing vascular occlusions or for treating septal defects and the like.
[0003] In certain circumstances, it may be necessary to occlude a patient's vessel, such as to stop blood flow through a vessel (artery or vein) or inside a defect in the heart to block or reduce blood flow to a site. Presently, this is commonly accomplished simply by inserting, for example, compressible nitinol-based plugs (eg. Amplatzer ASD occluder).
[0004] When using these devices to occlude an ASD, the pressure and therefore the chance of dislodgment of the device increase with the square of the size of the communication. Consequently, these devices have to have a very large retention skirt. Often times, the position, size, shape or anatomic plane of the ASD dictates the size of the retention skirt.
[0005] Additionally, the shape of the existing ASD occulder devices (for example squares, triangles, pentagons, hexagons and octagons and circular) require a larger contact area, having corners which extend to the free wall of the atria. Each time the atria contracts (approximately 100,000 times per day), internal wires within such devices are bent creating structural fatigue fractures in up to 30 percent of all cases.
[0006] The main problem of even the most recent devices is their propensity to protrude through the defect while being implanted. Further some of the existing devices have a shorter right atrial (RA) disc resulting in right to left embolization which could be life threatening. Furthermore, the previous devices require a French 14-16 introducing catheter, making it impossible to treat children affected with congenital defects with these devices.
[0007] There is accordingly a need for a versatile ASD occluder which may be made with a relatively small retention skirt. Further, there is a need to for a reliable embolization device which is both easy to deploy through a 6-7 French catheter and which can be accurately placed in a vessel. It would also be desirable to provide a recoverable device for deployment in a vessel in a patient's body which is both economical and yields consistent, reproducible results.
SUMMARY OF THE INVENTION
[0008] The present invention provides a reliable intravascular occlusion device which may be formed to treat, for example, Atrial Septal Defects (hereinafter ASD) and Patent Ductus Arteriosus (hereinafter PDA).
[0009] Atrial Septal Occluder Device (100) with a middle segment (110) comprising of at least four discs (110-140) wherein the middle segment (110) comprises of a right atrial disc (120), a right atrial lip (130), a left atrial disc (140) and a left atrial lip (150) for preventing embolization in the patient. The Atrial Septal Occluder Device (100) is made of resilient metal fabric with is stable and soft wherein the soft nature of the device (100) provides force of anchoring centripetal i.e., at the middle part of the defect which eliminates the erosion caused by the discs (110-140) touching the vital structures. The device (100) is constructed in a wide range of sizes ranging from a minimum of 4mm to any size depending on the size of the defect. The middle segment (110) is made of 3 sizes with various dimensions within fits wide range of morphologies and anatomic variations of the defects. The length of the middle segment (110) avoids the protruding of the device through the defect and thereby enables easy deployment of the device (100).
[00010] The most important characteristic of the device is its versatility and ease of deployment with stability and softness with potentially low or no risk of erosion. When forming these intravascular devices from a resilient metal fabric a plurality of resilient strands is provided, with the wires being formed by braiding to create a resilient material which can be heat treated to substantially set a desired shape. This braided fabric is then deformed to generally conform to a molding surface of a molding element and the braided fabric is heat treated in contact with the surface of the molding element at an elevated temperature. The time and temperature of the heat treatment is selected to substantially set the braided fabric in its deformed state. After the heat treatment, the fabric is removed from contact with the molding element and will substantially retain its shape in the deformed state. The braided fabric so treated defines an expanded state of a medical device which can be deployed through a catheter into a channel in a patient's body.
[00011] Further embodiments of the present invention also provide specific shapes for medical devices which may be made in accordance with the present invention to address predetermined medical procedures. Such devices of the invention are formed of a braided metal fabric and have an expanded configuration and a collapsed configuration. In use, a guide catheter can be positioned in a channel in a patient's body and advanced to position the distal end of the catheter adjacent a treatment site for treating a physiological condition.
[00012] A medical device, formed in a predetermined shape, and made in accordance with the process outlined above, can be collapsed and inserted into the lumen of the catheter. The device is urged through the catheter and out the distal end, whereupon, due to its memory property it will tend to substantially returns to its expanded state adjacent the treatment site. In accordance with a first of these embodiments, a generally elongate medical device has a generally tubular middle portion and a pair of expanded diameter portions, with one expanded diameter portion positioned at either end of the middle portion. In another embodiment, the medical device is generally hamburger shaped with multiple indentations in the middle segment. The middle and two ends are further covered with a fabric to prevent blood flow through the device.
BRIEF DESCRIPTION OF DRAWINGS
[00013] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[00014] FIG. 1 illustrates the graphical representation of the Atrial Septal Occluder Device (100) with a middle segment (110) comprising of at least four discs (110-140) wherein the middle segment (110) comprises of a right atrial disc (120), a right atrial lip (130), a left atrial disc (140) and a left atrial lip (150). The middle segment is unique with three different groves providing anchor, stability and versatility to close a variation of defect sizes and morphology.
[00015] FIG. 2A-2D illustrate embodiments of versatile atrial septal occluder devices, in accordance with the teachings of the present invention;
[00016] FIG. 5 illustrate methods for delivering the versatile atrial septal occluder devices of the present invention to occlude atrial septal defects.
DETAILED DESCRIPTION
[00017] The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment and are not intended to limit the scope thereof.
[00018] FIG. 1 illustrates the graphical representation of the Atrial Septal Occluder Device (100) with a middle segment (110) comprising of at least four discs (110-140) wherein the middle segment (110) comprises of a right atrial disc (120), a right atrial lip (130), a left atrial disc (140) and a left atrial lip (150). The middle segment is unique with three different groves providing anchor, stability, and versatility to close a variation of defect sizes and morphology.
[00019] The Atrial Septal Occluder Device (100) is made of resilient metal fabric with is stable and soft wherein the soft nature of the device (100) provides force of anchoring centripetal i.e., at the middle part of the defect which eliminates the risk of erosion caused by the discs (110-140) touching the vital structures. The device (100) is constructed in a wide range of sizes ranging from a minimum of 4mm to any size depending on the size of the defect. The middle segment (110) of each device is made of further 3 size variations with various dimensions within fits wide range of morphologies and anatomic variations of the defects. The length of the middle segment when stretched during deployment (110) avoids protrusion of the device through the defect and thereby enables easy deployment of the device (100).
[00020] Figures 2A to 2C are illustrations of various configurations for a versatile atrial septal occluder (VASO) device in accordance with the teachings of the present invention.
[00021] Figure 3A illustrates a profile of a first embodiment of the VASO device viewed from the left atrial (LA) disc side on the left.
[00022] Figure 3B illustrates a profile of the first embodiment of the VASO device viewed from the right atrial (LA) disc side on the right. The right atrial side (Figure 3B) shows the hub for attachment and detachment of the delivery system.
[00023] Figure 3C illustrates the first embodiment in a stretch configuration, exposing the middle segment of the VASO device with 3 grooves for anchoring on to the atrial septal margin. This is one of the unique features of the invention which makes the VASO device versatile as an anchoring mechanism. The middle disc has a U-shaped grove and either end has a deeper groove that is symmetrical on either side in this version.
[00024] Figure 3D illustrates the unstretched or natural profile of the first embodiment of the VASO device.
[00025] Figure 4A illustrates a second embodiment of the VASO device with a second configuration. The illustration in Figure 2D shows the profile of the VASO device from the RA side.
[00026] Figure 4B illustrates the second embodiment of the VASO device from the LA side.
[00027] Figure 4C illustrates the second embodiment of the VASO device in its unstretched or natural configuration.
[00028] Figure 4D illustrates the second embodiment of the VASO in a stretched configuration. It can be observed that compared the to the first embodiment, the groove or indentation within the central disc is shallower in the second embodiment, and the depth of the LA side groove or indentation is also shallower in the second embodiment.
[00029] Figure 5A illustrates a third embodiment of the VASO device with a third configuration. The illustration in Figure 4A shows the disc profile of the VASO device from the LA side.
[00030] Figure 5B illustrates the third embodiment of the VASO device in a stretched configuration. In this embodiment, the central disc is small and does not have a detectable groove or indentation. Grooves are however provided on either side of the middle disc. The third embodiment of the VASO device has been configured to be specifically suitable for closing complex patent foramen ovale (PFO).
[00031] Figure 5C illustrates a fourth third embodiment of the VASO device in a stretched configuration. Here the RA disc side is without a groove and connected directly to the RA disc. The LA side has a groove or indentation.
[00032] Figure 5D illustrates a stretched profile of another embodiment of the VASO device – wherein the central disc is larger with deeper groves on either ends.
[00033] The device of the present invention (including according to any of the embodiments described above and / or illustrated in the accompanying figures) provides a percutaneous catheter directed intravascular occlusion device for use in shunts in patients' bodies, such as vascular channels, urinary tracts, biliary ducts and the like. In forming a medical device via the method of the invention, a metal fabric based on Nitinol is provided. The fabric is formed of a plurality of wire strands having a predetermined relative orientation between the strands. Figures 2A and 2B illustrate examples of metal fabrics which are configured and braided to be suitable for use in the method of the invention.
[00034] Uses of Nitinol based products are now well established. The time and temperature of the heat treatment of Nitinol can vary greatly depending upon the material used in forming the wire strands. The nitinol used in making the wire strands of the fabric, the wire strands are very elastic when the metal is in its austenitic phase. This very elastic phase is frequently referred to as a "superelastic" or "pseudoelastic" phase. By heating the nitinol above a certain phase transition temperature, the crystal structure of the nitinol metal when in its austenitic phase can be set. This will tend to "set" the shape of the fabric and the relative configuration of the wire strands in the positions in which they are held during the heat treatment.
[00035] Suitable heat treatments of nitinol wire to set a desired shape are well known in the art. A wide body of knowledge exists for forming nitinol in such medical devices, so there is no need to go into great detail here on the parameters of a heat treatment for the nitinol fabric preferred for use in the present invention.
[00036] Holding a nitinol fabric at about 500"C to about 550"C for a period of about 1 to about 30 minutes, depending on the softness or harness of the device to be made, will tend to set the fabric in its deformed state, i.e. wherein it conforms to the molding surface of the molding element. At lower temperatures the heat treatment time will tend to be greater (e.g. about one hour at about 350"C) and at higher temperatures the time will tend to be shorter (e.g. about 30 seconds at about 900"C). These parameters can be varied as necessary to accommodate variations in the exact composition of the nitinol, prior heat treatment of the nitinol, the desired properties of the nitinol in the finished article, and other factors which will be well known to those skilled in this field.
[00037] After the heat treatment, the fabric is removed from contact with the molding element and will substantially retain its shape in a deformed state. Various shape modifications in different versions of the device are illustrated through the figures as described.
[00038] The relative sizes of the tubular middle section and the expanded diameter portions can be varied as desired. In this particular embodiment, the medical device is intended to be used as a vascular occlusion device to substantially stop the flow of blood through a patient's blood vessel. When the device is deployed within a patient's heart or blood vessel, as detailed below, it will be positioned within the vessel such that its axis generally coincides with the axis of the vessel. The dumbbell-shape of the present device is intended to limit the ability of the vascular occlusion device to turn at an angle with respect to the axis of the blood vessel to ensure that it remains in substantially the same position in which the operator deploys it within the vessel.
[00039] When it is deployed within the patient's heart or vessel, the vascular occlusion device will engage the lumen at spaced-apart locations based on the anatomic variation of the vessel or defect and the device self-configures the defect or vessel. . The device is desirably longer along its axis than the dimension of its greatest diameter. This will substantially prevent the VASO device from turning within the lumen at an angle to its axis, essentially preventing the device from becoming dislodged and tumbling along the vessel with blood flowing through the vessel.
[00040] The relative sizes of the generally tubular middle portion VASO and expanded diameter portion can be varied as desired for any particular application. For example, the outer diameter of the middle portion may range between about one quarter and about one third of the maximum diameter of the expanded diameter portions and the length of the middle portion may comprise about 30% to about 70% of the overall length of the device. Although these dimensions are suitable if the VASO device is to be used solely for occluding a vascular vessel, it is to be understood that these dimensions may be varied if the device is to be used in other applications, such as where the device is intended to be used simply as a flow restricting device with a central predetermined defect (Fenestrated VASO) rather than to substantially occlude the entire heart defect or vessel, where the device is deployed in a different channel in a patient's body.
[00041] When the device is deployed in a patient's vessel, thrombi will tend to collect on the surface of the wires. By having a greater wire density, the total surface area of the wires will be increased, increasing the thrombotic activity of the device and permitting it to relatively rapidly occlude the vessel or heart defect in which it is deployed. It is believed that forming the VASO device with stitched or coated membranous fabric inside will accelerate the occlusion rate. If it is desired to increase the rate at which the VASO device occludes the vessel or heart defect in which it is deployed, any of a wide variety of known thrombotic agents or fabric can be applied to the device.
[00042] The delivery device (not shown) can take any suitable shape, but desirably comprises an elongated, flexible braded shaft having such a recess at its distal end. The delivery device can be used to push the VASO device through its lumen. Once the proper position of the device 80 in the shunt is confirmed, the shaft of the delivery device can be rotated about its axis to unscrew the clamp 90 from the recess in the delivery means.
[00043] By keeping the VASO device attached to the delivery system means, the operator could still retract the device for repositioning if it is determined that the device is not properly positioned in the first attempt. This threaded attachment will also allow the operator to control the manner in which the device is deployed out of the distal end of the catheter. One of the major advantages of the design is that the versatile central disc design allows the LA disc to be positioned deep into the LA so that on pulling the disc to the septum the LA disc does not button hole through the defect as is the case with current devices in use.
[00044] As explained below, when the device exits the catheter, it will tend to resiliently return to a preferred expanded shape which is set when the fabric is heat treated. When the device springs back into this shape, it may tend to act against the distal end of the catheter, effectively urging itself forward beyond the end of the catheter. This spring action could conceivably result in improper positioning of the device if the location of the device within a channel is critical, such as where it is being positioned in a shunt between two vessels. Since the threaded clamp 90 can enable the operator to maintain a hold on the device during deployment, the spring action of the device can be controlled and the operator can control the deployment to ensure proper positioning.
[00045] Pulmonary vascular occlusive disease and pulmonary atrial hypertension develops in some patients with ASD. Regardless of age it is more common in Women. Patients with secundum ASD with a significant shunt (defined as a pulmonary blood flow to systemic blood flow ratio of greater than 1.5) are operated upon ideally at five years of age or whenever a diagnosis is made in later years. At the time of deployment of the device the pulmonary pressure and blood flow is usually calculated. If the PA pressure is elevated then a device with central hole to act as a pop off valve is needed. A fenestrated versatile atrial septal occluder (FVASO) device will be preferred in such instances. The FVASO occlusion device of this embodiment of the invention can advantageously be made in accordance with the method outlined before with a fenestration created by baiding adaptation to create a fenestration varying from 4mm to 12mm.
[00046] Those skilled in the art will recognize from the preceding discussion that the cavities of the mold must be shaped consistent with the desired shape of the VASO device. Also, it will be recognized that certain desired configurations may require that portions of the cavities be cammed. Figures 2C, 3D, 4B, 4C and 4D illustrate the VASO device with variations in the central disc and its modifications.
[00047] Figure 6 illustrates a catheter inserted through patient’s vein and advanced through the inferior vena cava and entering the defect between the two upper chambers of the heart called the Atrial Septal Defect (ASD). The catheter tip is placed in the left atria which will be used to deploy the VASO device using a delivery system to which the device is connected in a detachable fashion.
[00048] Figures 7A and 7B respectively illustrate a VASO device (according to the present invention) being advanced through a catheter delivery system. The red lines indicates margins of the hole in the heart located between the two upper chambers of the heart (Atrial Septal Defect or ASD). The device is precisely placed through a percutaneous catheter in patients diagnosed with ASD.
[00049] Figure 8 illustrates the VASO device according to the present invention after successful deployment, seated across the ASD after release from the delivery system. The device is re-conformed and precisely placed between the left and right atria snugging the inter atrial septum after release of the device closing the hole completely. The VASO device according to the claimed invention offers multiple advantages over the prior art , including the following:
[00050] A unique feature of the VASO device is its versatility. The device fits into varying anatomic and morphological variations of the atrial septal defect self-configuring itself to the anatomy. This is due to two specific factors unique to the device. The flexibility of the middle segment attributed to its special treatment and configuration, and the variations in the depth of the groves in the middle segment. This has been designed with variable depths from 5mm, 7mm, and 9mm from the LA disc to the RA disc respectively.
[00051] As a result of the configuration of the VAASO device, the clamping force is centered around the 'middle disc' so that the risk of erosion from the edges of the disc rubbing on the neighboring structures is avoided along with the softness of the wires used. Additionally, the variation in the profile of the central disc with 3 different sized groves (or variable size groves) help the anchoring of the device to variation in the defect morphology. The added length provided by the composite central body also provides extra length to the device so during deployment the device will not protrude back through the defect during deployment. Additionally, having same size discs on either end reduces further the risk of device embolization. The profile of the device makes it deliverable to smaller sheaths comparable to other deices currently available. The device design with variable middle segment makes the device versatile in closing a range of defect sizes with a single device. This means that different morphologies (like spiral defects, ASD tunnels, double septums Etc. can be closed by the device without the risk of embolization. The LA and RA discs are the same size, making device migration to either chambers less likely. The VASO device has the anchoring force in the middle segment that on the discs as in the case of existing devices. This is expected to substantially reduce or eliminate the risk of erosion of adjacent structures by the disc. This is a major disadvantage of currently available devices. The VASO device is easily retrievable to the special mechanical property of flexibility and compressibility. As the VASO device can be used to close ASD of wide ranges with varying disc diameters, the need for changing and using multiple devices before selecting the right size device and associated complications can be completely reduced by the special design of this device.
[00052] The VASO device middle and two ends are covered with a fabric or have special coating to prevent blood flow through the device and also allow tissue in-growth. The VASO device can be recaptured and redeployed ensuring accurate placement. The VASO device can be used to treat multiple fenestrated atrial septal defects.
[00053] While a preferred embodiment of the present invention has been described, it should be understood that various changes, adaptations and modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims.
,CLAIMS:I/We Claim:
1. Atrial Septal Occluder Device (100), comprising:
Atrial Septal Occluder Device (100) with a middle segment (110) comprising of at least four discs (110-140) wherein the middle segment (110) comprises of a right atrial disc (120), a right atrial lip (130), a left atrial disc (140) and a left atrial lip (150) for preventing embolization in the patient.
2. The Atrial Septal Occluder Device as claimed in claim 1 wherein the middle segment is unique with three different groves providing anchor, stability, and versatility to close a variation of defect sizes and morphology.
3. The Atrial Septal Occluder Device as claimed in claim 1 wherein the device (100) is made of resilient metal fabric with is stable and soft wherein the soft nature of the device (100) provides force of anchoring centripetal i.e., at the middle part of the defect which eliminates the erosion caused by the discs (110-140) touching the vital structures.
4. The Atrial Septal Occluder Device as claimed in claim 1 wherein device (100) is constructed in a wide range of sizes ranging from a minimum of 4mm to any size depending on the size of the defect.
5. The Atrial Septal Occluder Device as claimed in claim 1 wherein the middle segment (110) is made of 3 sizes with various dimensions within fits wide range of morphologies and anatomic variations of the defects.
6. The Atrial Septal Occluder Device as claimed in claim 1 wherein the length of the middle segment (110) avoids the protruding of the device through the defect and thereby enables versatility and ease of deployment with stability and softness with potentially low or no risk of erosion.
7. The Atrial Septal Occluder Device as claimed in claim 1 wherein intravascular device (100) formed from the resilient metal fabric with a plurality of resilient strands with the wires being formed by braiding to create a resilient material which can be heat treated to substantially set a desired shape.
8. The Atrial Septal Occluder Device as claimed in claim 6 wherein the braided fabric is deformed to conform to a molding surface of a molding element and the braided fabric is heat treated in contact with the surface of the molding element at an elevated temperature wherein the time and temperature of the heat treatment is selected to substantially set the braided fabric in its deformed state.
9. The Atrial Septal Occluder Device as claimed in claim 1 wherein the device (100) is formed in a predetermined shape and can be collapsed and inserted into the lumen of the catheter.
10. The Atrial Septal Occluder Device as claimed in claim 8 wherein the device (100) is urged through the catheter and out the distal end, whereupon, due to its memory property it will tend to substantially returns to its expanded state adjacent the treatment site.
11. The Atrial Septal Occluder Device as claimed in claim 1 wherein the device (100) is subject to fenestration at the middle of the device to achieve a fenestrated Atrial Septal Occluder Device.