1. Technical Field
This application relates to a device for preventing clot migration from the left atrial appendage of the heart.
2. Background of Related Art
The atrial appendage is a small muscular pouch or cavity attached to the atrium of the heart. The left atrial appendage (LAA) is connected to the wall of the left atrium between the mitral valve and the left pulmonary vein. In proper functioning, the left atrial appendage contracts with the rest of the left atrium during a heart cycle, ensuring regular flow of blood.
Atrial fibrillation is the irregular and randomized contraction of the atrium working independently of the ventricles. This resulting rapid and chaotic heartbeat produces irregular and turbulent blood flow in the vascular system, resulting in the left atrial appendage not contracting regularly with the left atrium. Consequently, the blood can become stagnant and pool in the appendage, resulting in blood clot formation in the appendage. If the blood clot enters the left ventricle it can enter the cerebral vascular system and cause embolic stroke, resulting in disability and even death.
One approach to treatment is the administration of medications to break up the blood clots. However, these blood thinning medications are expensive, increase the risk of bleeding and could have adverse side effects. Another approach is to perform invasive surgery to close off the appendage to contain the blood clot within the appendage. Such invasive open heart surgery is time consuming, traumatic to the patient, increases patient risk and recovery time, and increases costs as extended hospital stays are required.
It is therefore recognized that a minimally invasive approach to closing off the appendage to prevent the migration of blood clots into the ventricle and cranial circulation would be beneficial. These devices, however, need to meet several criteria.
Such minimally invasive devices need to be collapsible to a small enough dimension to enable delivery through a small incision while being expandable to a sufficiently large dimension with sufficient stability to ensure sealing of the appendage is maintained. These devices also need to be atraumatic. Further, the size of the appendage can vary among patients and therefore the devices need to be expandable to the appropriate size to close off the appendage.
There have been several attempts in the prior art to provide minimally invasive appendage closure devices. For example, in U.S. Pat. No. 6,488,689, a capture loop or clip is placed around the appendage to hold the appendage closed. These devices can be traumatic to the vascular structure. The Amplatzer occluder marketed by AGA Medical, provides for stent like expansion within a balloon. However, the diameter of expansion is not controllable and the collapsed configuration is relatively large, disadvantageously increasing the profile for insertion. In U.S. Pat. No. 6,152,144, an occluding member having an outer rim and a thin mesh barrier to provide a seal is placed at the opening of the appendage. Radially extending shape memory members extend from the shaft to anchor the device. An expandable anchoring member is also disclosed. In another embodiment, an occlusive coil having a random configuration is placed in the appendage to induce clot. U.S. Pat. Nos. 6,551,303 and 6,652,555 disclose a membrane placed across the ostium of the atrial appendage to prevent blood from entering. Various mechanisms such as shape memory prongs, anchors, springs and struts function to retain the membrane. These devices, however, suffer from various deficiencies.
Therefore, there is a need for an improved device for the left atrial appendage which will effectively block blood clot migration from the appendage, remain securely retained within the appendage, and have a reduced delivery profile to minimize the surgical incision and facilitate passage through the vascular system to the appendage.
The present invention overcomes the problems and deficiencies of the prior art. The present invention provides a device for placement in the left atrial appendage of a patient comprising a retention member and a material positioned within the retention member and unattached thereto. The retention member has a first elongated configuration for delivery and a second expanded configuration for placement within the left atrial appendage. The material is configured to float within the retention member in the expanded configuration of the retention member and cause blot clot within the appendage. The retention member has at least one appendage wall engagement member to secure the retention member to the appendage.
In some embodiments, in the second configuration, the retention member moves toward a shape memory position.
In one embodiment, the material comprises a mesh. In another embodiment, the material comprises a plurality of fibers. In another embodiment, the material comprises a plurality of ribbons. Combinations of these materials or use of other materials is also contemplated.
The present invention also provides in another aspect a device for placement in the left atrial appendage comprising a tube laser cut to form a series of struts, the tube having a first elongated configuration for delivery and a second configuration for placement. In the second configuration, the tube has an expanded configuration and the struts extend outwardly so that a distal region of the struts has a greater dimension than a proximal region and the struts define a space therebetween. A material is positioned within a region defined by the struts and unattached thereto for floating movement in the space between the struts, the material causing blood clots within the appendage.
In one embodiment, the material comprises a mesh. In another embodiment, the material comprises a plurality of fibers. In another embodiment, the material comprises a plurality of ribbons. Combinations of these materials or use of other materials is also contemplated.
In another aspect, a method for blocking blot clot migration from a left atrial appendage is also provided comprising the steps of inserting into the left atrial appendage a sheath containing a retention member having a plurality of struts in a reduced profile position, exposing the retention member from the sheath to enable it to expand to engage a wall of the left atrial appendage, subsequently inserting a material in situ within a space between the plurality of struts to enable the material to float within the space, and withdrawing the sheath to leave the retention member in the left atrial appendage so the material floats within the space defined by the plurality of struts to cause blood clots in the appendage.
Preferably, the retention member has a plurality of shape memory struts and the step of exposing the retention member enables the struts to move toward a shape memorized position.
Preferred embodiment(s) of the present disclosure are described herein with reference to the drawings wherein:
Referring now in detail to the drawings where like reference numerals identify similar or like components throughout the several views, the present invention provides a device for blocking blood clot migration from the left atrial appendage (“LAA”). The device can be inserted minimally invasively. The device includes a retention (securement) member and material unattached to the retention member and movably positioned therein to cause blood clots after a period of time. The retention member provides for attachment to the appendage wall as well as a retention structure to retain within the appendage the various embodiments of the blood clotting material described below.
With initial reference to
The mesh is not shown in
Turning to
The struts 17 can be interconnected by interconnecting struts 17a, 17b that curve outwardly away from the central axis then inwardly toward each other to form a V-shaped end portion with hook 14. The connecting struts 17a, 17b are joined to connecting struts of adjacent struts at region 25 at a distal portion. Thus, a closed geometric shape 33 is formed which can be substantially oval, substantially diamond shaped, or other shapes. A fewer or greater number of closed shapes can be formed. That is, the struts 17 preferably divide at region 19 into two connecting struts 17a, 17b, angling away from each other, and then join at region 25, extending distally, then angle away from each other at struts 17c, 17d to join an adjacent interconnecting strut (17c or 17d) terminating in hooks 14. Thus, in one embodiment, the thickness of the connecting strut 17a, 17b is about half the thickness of the strut 17 proximal of the bifurcation and about half the thickness of the region 25. The interconnecting struts 17 help to provide a retention structure to restrain the floating material positioned inside component 12. Thus, the configuration and spacing of the struts 17 prevent the mesh (or other material) from migrating out of the appendage, while enabling free floating movement within the appendage. The interconnecting struts 17 also stiffen the device to enhance retention and increase the radial force. They also provide a more symmetric and uniform deployment. The hooks 14 are configured to engage the appendage wall for maintaining the position of the device 10. The struts are preferably flared and create a distal opening and a space between the struts. For clarity, not all the identical parts are labeled throughout the drawings. It should be appreciated that materials other than Nitinol or shape memory are also contemplated.
The hooks 14 preferably extend substantially perpendicular from the strut and can be formed by torquing the struts so the hooks bend out of the plane. Preferably, a first set of hooks is larger than a second set of hooks, although hooks of the same size are also contemplated. Preferably, when formed in a laser cut tube, the larger hooks are formed so that they occupy a region equivalent to the transverse dimension of two adjacent struts. Preferably, three smaller hooks and three larger hooks are provided in alternating arrangement in the embodiment utilizing six struts. The smaller hooks are preferably spaced axially with respect to each other and axially inwardly with respect to the larger hooks as in the filter hooks of U.S. Pat. No. 7,704,266 to minimize the collapsed profile (transverse dimension) of the filter when collapsed for insertion. The penetrating tips 14a (
Each of the hooks 14 can have a series of teeth 14c to engage the appendage wall to provide additional retention to prevent movement of the device 10. A heel 14d can be provided which extends past the hook 14 to function as a stop to prevent the device from going through the wall. The angle of the heel 14d in the smaller hooks is preferably less than the angle in the larger hooks to provide room for nesting of the hooks as shown in
In an alternate embodiment, the struts 17′ terminate in blunt tips with the radial force of the struts maintaining the position of the device. This is shown for example in
The retention (securement) member 12 is maintained in a substantially straightened softer martensitic configuration within the delivery catheter or sheath 50 for delivery as shown in
As shown in
The device 10 in the embodiment of
The mesh 30 can be delivered within the retention member 12 such that in the collapsed position of the retention member 12, the mesh 30 is contained and compressed therein. After delivery, it would expand within the space of the retention member 12, i.e. within the space between the struts 17, since the struts expand when exposed from the delivery catheter.
In an alternate embodiment, the retention member 12 would be placed within the appendage first, and then once in place, the mesh 30 would be delivered through the spaces between the struts 17 for placement within the retention member 12.
The mesh 30 can be rolled up or folded for delivery. It can be one uniform piece or composed of two or more pieces of mesh.
In an alternate embodiment, instead of the mesh floating within the space between the struts, the material to induce blood clotting can be in the form of unorganized fibers as shown in
The fibers 120, like the aforedescribed mesh, are unattached to the retention member 112 and are floating, and preferably free floating, within the space defined by the struts 117 of the retention member 112, causing blood clots in the same manner as described above with respect to the floating mesh of
In an alternate embodiment of
The ribbons 215, like the aforedescribed mesh, are unattached to the retention member 212 and float within the space defined by the struts 217 of the retention member 212, and, preferably free float, causing blood clots in the same manner as described above with respect to the floating mesh of
The mesh (or other clot material such as ribbons or fibers) can be inserted with the retention member in a collapsed (compressed) state within the collapsed retention member or alternatively, if desired, can be delivered in situ within the opening between the struts in an already placed retention member. Such subsequent delivery could reduce the transverse dimension of the device in the collapsed position for delivery. The clot material can be inserted with the same catheter as the delivery catheter for the retention member or inserted by another catheter.
The method of placement of the device of the present invention will now be described for closing a left atrial appendage in conjunction with the embodiment of
A pusher 51 is advanced distally from a proximal end of the catheter 50 to advance the device 10 from the catheter 50 as shown in
In some embodiments, the retention member 12 will be positioned at the opening to the left atrial appendage B and be substantially flush with the opening. That is, the proximal retrieval hook would be positioned at the opening. Alternatively, a portion of the retention member 12 may extend proximally past the opening into the atrium as shown for example in
After placement within the appendage as shown in
As can be appreciated, the material described in the embodiments herein preferably free floats within the struts of the retention member, causing the blood to clot which then prevents migration of thrombus from the appendage into the atrium and left ventricle. The clot material floating within the retention member is preferably thrombogenic.
Note the material inside the retention member could be made of various materials, including, but not limited to, pericardium, SIS, PET, PTFE, etc.
In the alternate embodiment of
As can be appreciated, although described for use in the left atrial appendage of the heart, the device can also be used in other conduits such as blood vessels, ureters of fistulas.
While the above description contains many specifics, those specifics should not be construed as limitations on the scope of the disclosure, but merely as exemplifications of preferred embodiments thereof. For example, other materials can be contained or within the retention member to function to cause blood clot to block clot migration from the left atrial appendage. Those skilled in the art will envision many other possible variations that are within the scope and spirit of the disclosure as defined by the claims appended hereto.
This application is a continuation of application Ser. No. 13/008,990 filed Jan. 19, 2011, which claims priority from provisional application Ser. No. 61/337,972, filed Feb. 12, 2010. The entire contents of each of these applications are incorporated herein by reference.
Number | Date | Country | |
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61337972 | Feb 2010 | US |
Number | Date | Country | |
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Parent | 13008990 | Jan 2011 | US |
Child | 14967233 | US |