Heart occlusion devices

The present invention is specifically directed to a heart occlusion device with a self-centering mechanism. The heart occlusion device includes two separate uniquely shaped wires 12, 14, each forming shapes that mirror the respective wire's shapes. Each wire forms half-discs or quarter-discs that together form a distal disc and a proximal disc. In other versions, the device includes four separate wires, each mirroring its neighboring wire and forming a proximal and a distal quarter-disc. In the versions with four wires, the quarter-discs of each wire together form proximal and distal discs. The distal disc and proximal disc are separated by a self-centering waist. The proximal disc is attached to a hub comprising a screw mechanism. A similar hub is optional on the distal disc. The discs further include coverings which form a sealant to occlude an aperture in a tissue. The wires forming the discs have a shape-memory capability such that they can be collapsed and distorted in a catheter during delivery but resume and maintain their intended shape after delivery.

FIELD OF THE INVENTION

The present invention is directed to a medical device and particularly to a device for closing congenital cardiac defects. The present invention is specifically directed to a heart occlusion device with a self-centering mechanism.

DESCRIPTION OF THE PRIOR ART

A specific example of one such heart defect is a PFO. A PFO, illustrated inFIG. 1at6A, is a persistent, one-way, usually flap-like opening in the wall between the right atrium2and left atrium3of the heart1. Because left atrial (LA) pressure is normally higher than right atrial (RA) pressure, the flap usually stays closed. Under certain conditions, however, right atrial pressure can exceed left atrial pressure, creating the possibility that blood could pass from the right atrium2to the left atrium3, and blood clots could enter the systemic circulation. It is desirable that this circumstance be eliminated.

The foramen ovale6A serves a desired purpose when a fetus is gestating in utero. Because blood is oxygenated through the umbilical chord and not through the developing lungs, the circulatory system of the fetal heart allows the blood to flow through the foramen ovale as a physiologic conduit for right-to-left shunting. After birth, with the establishment of pulmonary circulation, the increased left atrial blood flow and pressure results in functional closure of the foramen ovale. This functional closure is subsequently followed by anatomical closure of the two over-lapping layers of tissue: septum primum8and septum secundum9. However, a PFO has been shown to persist in a number of adults.

The presence of a PFO defect is generally considered to have no therapeutic consequence in otherwise healthy adults. Paradoxical embolism via a PFO defect is considered in the diagnosis for patients who have suffered a stroke or transient ischemic attack (TIA) in the presence of a PFO and without another identified cause of ischemic stroke. While there is currently no definitive proof of a cause-effect relationship, many studies have confirmed a strong association between the presence of a PFO defect and the risk for paradoxical embolism or stroke. In addition, there is significant evidence that patients with a PFO defect who have had a cerebral vascular event are at increased risk for future, recurrent cerebrovascular events.

Accordingly, patients at such an increased risk are considered for prophylactic medical therapy to reduce the risk of a recurrent embolic event. These patients are commonly treated with oral anticoagulants, which potentially have adverse side effects, such as hemorrhaging, hematoma, and interactions with a variety of other drugs. The use of these drugs can alter a person's recovery and necessitate adjustments in a person's daily living pattern.

In certain cases, such as when anticoagulation is contraindicated, surgery may be necessary or desirable to close a PFO defect. The surgery would typically include suturing a PFO closed by attaching septum secundum to septum primum. This sutured attachment can be accomplished using either an interrupted or a continuous stitch and is a common way a surgeon shuts a PFO under direct visualization.

Umbrella devices and a variety of other similar mechanical closure devices, developed initially for percutaneous closure of atrial septal defects (ASDs), have been used in some instances to close PFOs. These devices potentially allow patients to avoid the side effects often associated with anticoagulation therapies and the risks of invasive surgery. However, umbrella devices and the like that are designed for ASDs are not optimally suited for use as PFO closure devices.

Currently available septal closure devices present drawbacks, including technically complex implantation procedures. Additionally, there are not insignificant complications due to thrombus, fractures of the components, conduction system disturbances, perforations of heart tissue, and residual leaks. Many devices have high septal profile and include large masses of foreign material, which may lead to unfavorable body adaptation of a device. Given that ASD devices are designed to occlude holes, many lack anatomic conformability to the flap-like anatomy of PFOs. The flap-like opening of the PFO is complex, and devices with a central post or devices that are self-centering may not close the defect completely, an outcome that is highly desired when closing a PFO defect. Hence, a device with a waist which can conform to the defect will have much higher chance of completely closing the defect. Even if an occlusive seal is formed, the device may be deployed in the heart on an angle, leaving some components insecurely seated against the septum and, thereby, risking thrombus formation due to hemodynamic disturbances. Finally, some septal closure devices are complex to manufacture, which may result in inconsistent product performance.

Devices for occluding other heart defects, e.g., ASD, VSD, PDA, also have drawbacks. For example, currently available devices tend to be either self-centering or non-self-centering and may not properly conform to the intra-cardiac anatomy. Both of these characteristics have distinct advantages and disadvantages. The non-self centering device may not close the defect completely and may need to be over-sized significantly. This type of device is usually not available for larger defects. Further, the self-centering device, if not sized properly, may cause injury to the heart.

Some have sharp edges, which may damage the heart causing potentially clinical problems.

Some devices contain too much nitinol/metal, which may cause untoward reaction in the patient and hence can be of concern for implanting physicians and patients.

Some currently marketed devices have numerous model numbers (several available sizes), making it difficult and uneconomical for hospitals and markets to invest in starting a congenital and structural heart interventional program.

The present invention is designed to address these and other deficiencies of prior art aperture closure devices.

SUMMARY OF THE INVENTION

The present invention is directed to a heart occlusion device with a self-centering mechanism comprising two separate, uniquely-shaped wires wherein each wire is shaped into two semi-circular designs to form two half-discs by the memory-shaping capability of the wires, a self-centering waist area formed between the two semi-circular designs, and a covering over the each of the two semi-circular designs, wherein the covering is a sealant from the heart occlusion.

More specifically, the present invention is directed to a device for occluding an aperture in tissue comprising a first flexible wire and a second flexible wire, wherein each of the first and second wires is comprised of a shape memory properties, and wherein each of the first and second wires is shaped into first and second generally semi-circular forms such that the first semicircular form of the first wire opposes the first semicircular form of the second wire to form a first disc and the second semicircular form of the first wire opposes the second semicircular form of the second wire to form a second disc wherein further each of the first and second discs is separated by a self-centering waist formed from two sections of the first wire and two sections of the second wire; and a sealed covering over each of the first and second discs, wherein the covering provides a seal to occlude the aperture.

The present invention is also directed to a device for occluding an aperture in a heart tissue comprising a first flexible wire and a second flexible wire. Each of the first and second wires is comprised of a shape memory property. Further, each of the first and second wires is shaped into first and second generally semi-circular forms such that the first semicircular form of the first wire opposes the first semicircular form of the second wire to form a first disc and the second semicircular form of the first wire opposes the second semicircular form of the second wire to form a second disc. Each of the first and second discs is separated by a self-centering waist formed from two sections of the first wire and two sections of the second wire, and wherein the two sections of the first wire and two sections of the second wire create an outward radial force to maintain the self-centering configuration of the device. Each of the first and second wires has a first and second end and wherein each of the first and second ends of the first and second wires is connected to a hub, wherein the hub further comprises a delivery attachment mechanism for attachment to a deployment cable. The device also includes a sealed covering over each of the first and second discs, wherein the covering provides a seal to occlude the aperture wherein the coverings comprise a flexible, biocompatible material capable of promoting tissue growth and/or act as a sealant.

The present invention is also directed to a method for inserting the occluder device described above into an aperture defect in a heart to prevent the flow of blood therethrough. The method comprises:a. attaching the occluder device to a removable deployment cable,b. placing the occluding device within a flexible delivery catheter having an open channel,c. feeding the catheter into a blood vessel and advancing the catheter via the blood vessel system to the aperture defect in the heart,d. advancing the catheter through the aperture defect,e. withdrawing the catheter from the occluder device such that the first disc of the occluder device expands on one side of the aperture defect,f. further withdrawing the catheter from the occluder device such that the second disc of the occluder device expands of the other side of the aperture defect, such that the waist of the occluder device expands by memory retention within the aperture defect to self-center the occluder device,g. further withdrawing the catheter from the blood vessel; andh. removing the deployment cable from the hub.
Advantages:

The device of the present invention has many advantages:Lower Profile: The occluder device of the present invention has a lower profile than available devices,Conformable: The device is flexible and conformable to the patient anatomy, specifically the hole that is being closed. There are no sharp edges. The device is soft and hence less traumatic to the atrial tissue.Self-Centering on Demand: Because of the unique way the two discs are connected, the device has self-centering characteristics. The uniqueness of this device is in the self-centering mechanism. The waist of the device is made of four wires. The wires will have the capability to conform to the shape and size of the defect in the organ—a characteristic not seen in prior art devices. Therefore, the self-centering of the device is dependent upon the size and the shape of the defect. The wires will have enough radial force to maintain the self-centering configuration but will not be strong enough to press against the defect edges in a manner that exacerbates the defect. The device is fully repositionable and retrievable after deployment.Custom Fit: The device has the further ability to be custom-fit within the defect with balloon-expansion of the waist. Because of the self-expanding nature of the waist, this will not be needed in most cases. However, in cases in which custom expansion is needed (oval defects, tunnel defects), the waist size can be increased to conform to the defect by the balloon catheter expansion. A balloon may be inserted through a hollow screw attachment on the device's delivery hub and delivery cable. The expansion will be possible before the release of the device, which will increase the margin of safety.Fewer Sizes: The expandable waist requires fewer sizes to close a wider variety of differently-sized defects. Thus, a single device may offer physicians the ability to implant devices in several different sizes.The device will be less thrombogenic as the discs will be covered with ePTFE. The ePTFE has been time-tested and found to be least thrombogenic. There is the ability to close defects up to 42 mm with very mild modifications.Security: There will be the opportunity to remain tethered to the implanted device before releasing it, which is an extra security feature.
Uses:

The device of the present invention should be appropriate for an ASD (atrial septal defect), PFO (patent foramen ovale), VSD (ventricular septal defect), and PDA (patent ductus arteriosus) with minor modifications.

An important use of the device will also be in closure of an aperture in a left atrial appendage. The device can be modified to conform to the atrial appendage anatomy. The discs are modified so that the device is not extruded out with the heartbeats. Yet, the device is still soft enough to form adequate closure.

The discs can also be modified so that they become compatible for closure of veins and arteries. For this use, the connecting waist will become equivalent (or near equivalent) to the diameter of the discs. Other important uses will be in closure of coronary artery fistulas, arteriovenous fistulas, arteriovenous malformations, etc.

The objects and advantages of the invention will appear more fully from the following detailed description of the preferred embodiment of the invention made in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a device for occluding an aperture within body tissue. One skilled in the art will recognize that the device and methods of the present invention may be used to treat other anatomical conditions in addition to those specifically discussed herein. As such, the invention should not be considered limited in applicability to any particular anatomical condition.

FIG. 1illustrates a human heart1, having a right atrium2, a left atrium3, a right ventricle4, and a left ventricle5. Shown are various anatomical anomalies6A,6B, and6C. The atrial septum7includes septum primum8and septum secundum9. The anatomy of the septum7varies widely within the population. In some people, the septum primum8extends to and overlaps with the septum secundum9. The septum primum8may be quite thin. When a PFO is present, blood could travel through the passage6A between septum primum8and septum secundum9(referred to as “the PFO tunnel”). Additionally or alternatively, the presence of an ASD could permit blood to travel through an aperture in the septal tissue, such as that schematically illustrated by aperture6B. A VSD is similar to an ASD, except that an aperture6C exists in the septum between the left and right ventricle of the heart.

PDA results from defects in the ductus arteriosus. The human blood circulation comprises a systemic circuit and a pulmonary circuit. In the embryonic phase of human development, the two circuits are joined to one another by the ductus arteriosus. The ductus connects the aorta (circulation to the body) to the pulmonary artery (pulmonary circuit). In normal development of an infant, this ductus closes after birth. If development is defective, it can happen that the ductus does not close, and as a result the two blood circuits are still joined even after birth.

Unless specifically described otherwise, “aperture”6will refer to the specific heart defects described above, including PFO6A, ASD6B, VSD6C, and PDA among others.

As used herein, “distal” refers to the direction away from a catheter insertion location and “proximal” refers to the direction nearer the insertion location.

As used herein, “memory” or “shape memory” refers to a property of materials to resume and maintain an intended shape despite being distorted for periods of time, such as during storage or during the process of delivery in vivo.

Referring now toFIGS. 2-5, the occluder device10of the present invention comprises two separate uniquely shaped memory wires12,14. The wire can be formed of biocompatible metals or polymers, such as bioresorbable polymers, shape memory polymers, shape memory metal alloys, biocompatible metals, bioresorbable metals, or combinations thereof. Specific examples include but are not limited to iron, magnesium, stainless steel, nitinol, or combinations of these and similar materials. A preferred metal for the present invention is a nitinol alloy. Nitinol (an acronym for Nickel Titanium Naval Ordnance Laboratory) is a family of intermetallic materials, which contain a nearly equal mixture of nickel (55 wt. %) and titanium. Other elements can be added to adjust or “tune” the material properties. Nitinol exhibits unique behavior, specifically, a well defined “shape memory” and super elasticity. In general, any biocompatible material with a memory capability can be used with the present invention. The thermal shape memory and/or superelastic properties of shape memory polymers and alloys permit the occluder10to resume and maintain its intended shape in vivo despite being distorted during the delivery process. In certain embodiments, the memory may also assist in pressing an aperture, such as a PFO tunnel, closed. The diameter or thickness of the wire depends on the size and type of the device, i.e., the larger the device, the larger the diameter of the wire. In general, wire having a diameter between about 0.2 mm and 0.8 mm can be used.

As shown inFIGS. 2-5, each wire12or14forms a shape which mirrors that of the respective wire14or12. Specifically, each wire12,14forms a distal semi-circle or half-disc12A14A in addition to two proximal quarter-circles or quarter-discs12B,12B′ or14B,14B′. The two proximal quarter-circles of each wire together form proximal semi-circles or half-discs12B,12B′ or14B,14B′. The two distal semi-circles of each respective wire12A,14A together comprise a distal circle or distal disc16of the occluder10. The four proximal quarter-circles12B,12B′,14B,14B′, which form a “four-leaf clover” configuration, comprise a proximal circle or proximal disc18of the occluder10.

The proximal semi-circle12B,12B′ or14B,14B′ of each wire is connected to the distal semi-circle12A or14A by waist portions12C,14C. As shown inFIG. 2, there are two waist portions12C,14C per wire. The four waist portions (two from each wire)12C,14C together comprise a restricted area or waist20of the occluder device10. The distance between the waist portions, both within the same wire and from wire to wire, determines the size of the waist20. The size of the waist20is dependent on the particular application and the size of the occluder device10. The resiliency and memory of the waist portions12C,14C and capacity to expand radially serves as a self-centering mechanism of the occluder device10in apertures6.

The Hub30:

The two half-discs are not attached or joined to each other except at the junction of the delivery attachment mechanism or hub30. The ends12D,14D of wires12,14will be welded or otherwise connected to the hub30.

According to some embodiments of the present invention, the distal disc16and/or proximal disc18may include membranous coverings24A and24B illustrated inFIGS. 6 and 7. The membranous coverings24A and24B ensure more complete coverage of aperture6and promote encapsulation and endothelialization of tissue, thereby further encouraging anatomical closure of the tissue and improving closure rate. The coverings24A and24B also help stabilize the occluder device10.

The membranous coverings24A and24B may be formed of any flexible, biocompatible material capable of promoting tissue growth and/or act as a sealant, including but not limited to DACRON®, polyester fabrics, Teflon-based materials, ePTFE, polyurethanes, metallic materials, polyvinyl alcohol (PVA), extracellular matrix (ECM) or other bioengineered materials, synthetic bioabsorbable polymeric materials, other natural materials (e.g. collagen), or combinations of the foregoing materials. For example, the membranous coverings24A and24B may be formed of a thin metallic film or foil, e.g. a nitinol film or foil, as described in U.S. Pat. No. 7,335,426 (the entirety of which is incorporated herein by reference). The preferred material is Poly(tetrafluoroethene) (ePTFE) as it combines several important features such as thickness and the ability to stretch. Loops may also be stitched to the membranous coverings24A and24B to securely fasten the coverings to occluder10. The coverings may alternatively be glued, welded or otherwise attached to the occluder10via the wires12,14.

As illustrated inFIGS. 2-7, the diameters of the distal disc16and proximal disc18are generally 5-8 mm larger than the diameter of the connecting waist20. For example, if the diameter of the connecting waist20is 4 mm, the diameters of the discs16,18are generally about 9 mm each. Because of the flexibility in the waist20, a 12 mm waist device will be able to be placed in a 6 mm to 12 mm defect. For larger waists20or larger devices, the diameter of the disc size will increase proportionately.

It is within the scope of the present invention to envision occluder devices available in 7 or more sizes, specifically waist size having the following diameters for different-sized apertures6: 6 mm, 12 mm, 18 mm, 24 mm, 30 mm, 36 mm, and 42 mm.

In general, the occluder10may be inserted into an aperture6to prevent the flow of blood therethrough. As a non-limiting example, the occluder10may extend through a PFO6A or an ASD6B such that the distal disc16is located in the left atrium3and the proximal disc18is located in the right atrium2(as shown in the heart1inFIG. 1). The closure of apertures in these and other tissues, as well as other types of apertures, will become apparent as described below.

Referring now toFIGS. 8-10, the occluder device10is attached to a deployment cable34which is removably attached to the occluder device10at the hub30. As illustrated inFIG. 10, one method of releasably attaching the deployment cable34to the hub30is by threaded engagement utilizing a screw end36which engages unseen female threads within the hub30. Other known means of attachment can be used to releasably connect the deployment cable34to the hub30.

When the deployment cable34is engaged with the hub30, as illustrated inFIGS. 8 and 9, the occluder device10is initially housed within a flexible delivery catheter40having an open channel42. Reference is made toFIG. 8which illustrates the occluder device10in which the distal disc16is expanded, due to the memory expansion of the wires12and14, and housed within the open channel42of the delivery catheter40. During the initial stages of placement of the occluder device10, both the distal disc16and proximal disc18as well as the coverings24A and24B are housed within the open channel42of the delivery catheter40. In this manner, the catheter40is fed into the blood vessel through an already placed sheath and advanced via the blood vessel system to a defect in the heart

Once the delivery catheter40traverses the aperture that needs to be occluded, e.g., a hole in the heart, the device10will be partially advanced from the catheter40as illustrated inFIG. 8. As the device10leaves the catheter40, the distal disc16, which includes the covering24A, begins to expand on the distal side of the aperture. Due to the memory capabilities of the wires12and14, the occluder device10begins to return to its normal shape such that the distal disc16expands on distal side of the aperture in the heart. Once the distal disc16is completely out of the catheter opening42, as show inFIG. 9, it16and the attached covering24A become fully expanded. The catheter40is further withdrawn to expose the waist20which then begins to emerge and expand due to the memory shape of the wires12and14. Advantageously, the waist20is designed to expand such that each of the wires forming the waist20are urged against the aperture in the heart causing a custom fit device of the occluder10within the aperture. As the catheter40is further withdrawn, the proximal disc18and the covering24B begin their process of expansion on the proximal side of the aperture. When the proximal disc18is fully delivered from the catheter40, it will expand and effectively form a seal over the aperture. The distal disc16and proximal disc18are secured in place by the action of the wires in the waist20urging against the aperture. At this stage, as shown inFIG. 10, the deployment cable34is removed from the hub30and the catheter40and the deployment cable34are removed from the body. The occluder device10is left in the heart at the region of the aperture. Over several months, skin tissue and other membranous structures will bind to the occluder device10thereby permanently locking the occluder device10to the specific area in the heart.

The two wires12,14function to form round discs16,18on each side of the tissue. The discs16,18maintain the circular shape because of the memory capability of the wires12,14. The coverings24A,24B will stabilize the discs and will act to completely occlude the defect.

The wires12,14at the waist portions12C,14C will be separated enough at the waist20to make the occluder device10self-centering. Due to the conformity of this design, the occluder device10should self-center within commonly (round, oval) shaped septal defects as the waist20can adjust to any type of opening.

If a larger-diameter waist20is required, the waist20has the capability to expand (only if needed) to a larger size with the help of a balloon. In this manner, a center channel50extends through the deployment cable34, the hub30, and the screw end36. A balloon (not shown) is urged through the center channel50after the occluder device has been removed from the catheter40and expanded. The balloon is placed within the waist20and expanded. The waist20is dilatable, i.e., expandable, when gentle pressure of the balloon is applied. The dilation will expand the waist portions12C,14C. Once the desired diameter is reached, the balloon is deflated and removed by withdrawal through the center channel50. Once the occluder device10appears stable, the device10is separated from the deployment cable34as discussed above. In the majority of cases, balloon dilation will not be required.

In order to increase stability in the occluder device10and to avoid significant crimping of the waist20or the proximal or distal discs18,16, the waist20can be encircled by one or more restriction wires60,62as illustrated inFIG. 11. The restriction wires60,62can be made of the same wire material as the wires12and14, or the may be of a different material, such as plastic wire, fish line, etc. The restriction wires60,62may be welded or otherwise connected to the waist portions12C,14C. The purpose of the restriction wires60or62is also to restrict the circumference of the waist20if necessary. Although one restriction wire60is generally suitable, a second restriction wire62can also be incorporated to further improve stability.

Alternative Embodiments

Reference is now made toFIGS. 12-15for alternative embodiments of the occluder device10of the present invention. Unless otherwise noted, the same reference numbers will be applied to similar structures in each embodiment.

Reference is made toFIGS. 12A and 12Bfor an alternative embodiment of the occluder device100. The occluder device100in this embodiment is designed for PDA procedures. This embodiment is similar to previously described embodiments except that it is comprised of four wires112,114,116,118rather than two wires. In this case, each wire forms a mirror image of each of its neighboring wires. For example, wire112mirrors wire114as well as wire118, etc. Each of the four wires112,114,116,118forms a proximal quarter-disc112B,114B,116B,118B and a distal quarter-disc112A,114A,116A,118A. The proximal quarter-discs112B,114B,116B,118B together form a proximal disc111in a “four-leaf clover” configuration, and the distal quarter-discs112A,114A,116A,118A together form a distal disc110also in a “four-leaf clover” configuration. This embodiment also differs from previously-described embodiments in that the waist20is comprised of a single portion of each of the four wires112,114,116,118. This embodiment further differs from previously-described embodiments in that it comprises a second hub119with a screw mechanism. The second hub119connects to the distal disc110by distal ends112E,114E (116E,118E behind112E,114E inFIG. 12B) of each of the four wires112,114,116,118, just as proximal ends112D,114D (116D,118D behind112D,114D inFIG. 12B) connect to the proximal hub30. The wires112,114,116,118may be connected to the hubs30,119by welding or other means known in the art. The length of the waist20will be anywhere from 4-8 mm. In addition, the distal disc110is typically 4-8 mm larger than the waist20. However, the proximal disc111is generally 1-3 mm, preferably 2 mm, larger than the waist20diameter. Hence, the diameter of the distal disc110is larger than the diameter of the proximal disc111.

Reference is now made toFIG. 13for a second alternative embodiment of the occluder device120. This embodiment, like the embodiment shown inFIGS. 12A and 12B, uses four wires112,114,116,118and two hubs30,119. It is designed to close apertures in large arteries and veins. In occluder device120, the distal and proximal discs122and124are modified so that they are compatible with closure of veins and arteries. For this use, the connecting waist20is equivalent or near equivalent to the diameter of each of the discs122,124. The diameter of the waist20will be 1 mm smaller than the discs122,124. The length of the waist will be 4-8 mm. This embodiment can be used in the closure of coronary artery fistulas, arteriovenous fistulas, and arteriovenous malformations.

Reference is made toFIG. 14for a third alternative embodiment of the occluder device130. The importance of the occluder device130will be in the closure of the left atrial appendage. The device130is modified to conform to the atrial appendage anatomy. The distal disc132is modified so that the device130is not extruded out with the heartbeats. For the left atrial appendage occluder device130, the memory wire structure of the distal disc132is woven to form anywhere from 2 to 8 protuberances or hooks136. Upon inserting the device10in an aperture in the left atrial appendage of the heart, the hooks136grip the outer portion of the left atrium heart tissue and thereby assist in keeping the device130from extruding out of the left atrial appendage with contraction of the heart. The proximal disc134is typically flat and similar to the disc formed by the proximal discs18inFIGS. 2-7. The proximal disc134abuts the inner atrial wall of the heart. Typically, the waist20will be about 4-8 mm in diameter. The length of the waist may range from 4 to 16 mm.

Reference is made toFIG. 15for a fourth alternative embodiment of the occluder device140. Occluder device140is intended occlude perimembranous ventricular septal (“PVS”) defects. This embodiment, like the embodiment shown inFIGS. 12A and 12B, uses four wires112,114,116,118and two hubs30,119. The occluder device140is different from other embodiments in that two of the four wires form truncated distal-quarter discs, with the effect that the distal disc142substantially misses half of the disc. Therefore, the device140has approximately 1.5 discs as opposed to two discs. The half distal disc142is also significantly longer than the proximal disc144. Typically, the distal disc142will be 6-8 mm in diameter. In addition, the distal disc142converges or curves inwards at143, i.e., it is angled to contact the ventricular septum when the device140is inserted in the PVS defect. (See below for details.) The lower edge of the proximal disc (opposite to the long distal disc) will be 3-4 mm larger than the waist and the other half of the proximal disc will be 2-3 mm larger than the waist. The discs can also be modified to be of different shapes in the same device. Alternatively, the disc angle may be created by a straight distal disc142angled with respect to the plane perpendicular to the waist20in a slant fashion.

Other embodiments may comprise any combinations of the embodiments described explicitly herein. It is understood that the invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces such modified forms thereof as come within the scope of the following claims.