FLOW DIVERSION DEVICE
A flow diversion device for the treatment of intracranial aneurysms and other medical conditions is disclosed. The flow diversion device may include a generally tubular wire stent frame formed from a plurality of zig-zag shaped wire elements that are coupled together. The device further includes a base layer of graft material coupled to the wire stent frame and surrounding at least a portion thereof, the wire stent frame maintaining the base layer in an open condition. In some embodiments, the base layer may be formed of porous graft material having a plurality of pores formed thereon to provide a passageway for a small blood flow to maintain the long term patency of important small side branches, while also reducing blood flow to the aneurysm to promote occlusion and avoid potential rupture.
This application is a nonprovisional of and claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 62/088,379, filed Dec. 5, 2014, the disclosure of which is incorporated by reference herein in its entirety.TECHNICAL FIELD
The field of the present disclosure relates generally to medical devices, and in particular, to flow diversion devices that may be used for treatment of wide-neck and fusiform aneurysms.BACKGROUND
Flow diversion devices, such as the Pipeline embolization device, the Surpass flow diverter, and the Silk flow diverter, are stent-like devices composed of tightly-braided, thin wire elements typically used for the treatment of intracranial aneurysms. These devices are employed endovascularly to treat aneurysms by diverting blood flow away from the aneurysm to induce aneurysm thrombosis, which helps prevent rupture of the aneurysm and may eventually result in the gradual shrinkage and occlusion of the aneurysm. In addition, when used for fusiform aneurysms (i.e., aneurysms with no definable neck), the flow diversion device may promote reconstruction of a smooth endothelial covered channel in continuation with the parent artery. While the flow diversion device directs blood away from the aneurysm, the thin-wire braided design allows modest through-flow of blood to maintain the patency of important small arterial side branches adjacent to the treated aneurysm.
Large intracranial aneurysms (which range in diameter from 10-25 mm) and particularly giant intracranial aneurysms (those greater than 25 mm in diameter) frequently have a wide-neck (dome-to-neck diameter ratio of less than 2) or are fusiform. Typically, large and giant aneurysms have poor occlusion, rupture and survival rates regardless of the form of therapy (e.g., open brain surgery or other endovascular techniques) used to treat them. The use of finely braided stent devices to divert blood flow away from aneurysms has yielded promising treatment results compared to open surgery and other conventional endovascular techniques, such as coil embolization with or without the assistance of an endovascular stent or balloon remodeling.
With reference to the drawings, this section describes particular embodiments and their detailed construction and operation. The embodiments described herein are set forth by way of illustration only and not limitation. The described features, structures, characteristics, and methods of operation may be combined in any suitable manner in one or more embodiments. In view of the disclosure herein, those skilled in the art will recognize that the various embodiments can be practiced without one or more of the specific details or with other methods, components, materials, or the like. For the sake of clarity and conciseness, certain aspects of components or steps of certain embodiments are presented without undue detail where such detail would be apparent to those skilled in the art in light of the teachings herein and/or where such detail would obfuscate an understanding of more pertinent aspects of the embodiments.
The present inventor has recognized some disadvantages relating to current flow diversion devices. For example, one disadvantage is that the very fine braids in the wire mesh tube of current devices make it challenging to deliver the device intracranially, usually requiring larger diameter and stiffer microcatheters to advance the collapsed stent device to the target region of the affected artery. In some circumstances, these large bore, stiffer microcatheters may be unstable and lead to inadvertent displacement of the flow diversion device into the aneurysm cavity. Moreover, once in place, the construction of such stent devices may make their expansion somewhat difficult, which may cause undesired effects, such as: (1) leading to blockage of normal blood flow to part of the brain, thereby threatening a stroke, and (2) creating undesirable space between the outer surface of the stent and the blood vessel interior or intima, thereby permitting side branches to create an endoleak, which may result in the undesirable maintenance of flow into the aneurysm cavity.
Another disadvantage of such current flow diversion devices is that positional instability of the device during deployment may cause the device to unexpectedly kick back into the aneurysm. In addition, such current devices may also create a large metal burden for the treated artery, which may increase the risk for thromboembolic events and require prolonged therapy or treatment.
As further described in detail below, certain embodiments described herein may be capable of achieving various advantages, including one or more of the following: (1) providing a flow diversion device with a streamlined design to simplify endovascular introduction and decrease forces placed on the delivery catheter; (2) providing such a flow diversion device constructed to promote expansion of the device once in position for improved flow; and (3) providing a flow diversion device that effectively diverts blood away from an aneurysm while maintaining sufficient blood flow to maintain patency of arterial side branches adjacent the aneurysm treatment site. Additional aspects and advantages will be apparent from the following detailed description of example embodiments, which proceeds with reference to the accompanying drawings.
With particular reference to
In some embodiments, the wire elements 105 may be coupled together, such as via a welding process, in a staggered or alternating pattern at one or more sites to create an “open cell” design capable of following sharp curves in blood vessels without kinking. For example, with particular reference to
In some embodiments, the flow diversion device 100 may use or include few wire elements 105 to minimize resistance while the device 100 is advanced to a target site. In addition, the diameter of each of these wire elements 105 is selected to ensure each wire element 105 possesses sufficient expansive force once the flow diversion device 100 is deployed at the target site, thereby decreasing the chance of incomplete expansion, and in turn, avoiding a dangerous blockage of blood flow. For example, in one embodiment, the diameter of each wire element 105 may be equal to or less than 0.005 inches to create a flow diversion device 100 with sufficient stiffness, flexibility, and proper expansile forces to help ensure that the flow diversion device 100 is securely fixed to the target vessel site to cover the neck of an aneurysm or provide a flow pathway through a fusiform aneurysm as further described with particular reference to
With reference to
In some embodiments, the perforations/pores 140 may be designed and cut on the base layer 135 such that the perforations/pores 140 enlarge or change shape with increased flow demand. For example, the perforations/pores 140 may be half-circle incisions or slits, in a similar pattern as is typically found in a flag. As the blood flow against the base layer 135 increases, the half-circle incisions allow a flap of graft fabric to fold away (relative to the direction of blood flow) and prevent excess billowing of the base layer 135 (which might result in its tearing or dislodgement). Preferably, in the absence of any special characteristics of the perforations/pores 140, the porous graft material of the base layer 135, nonetheless, provides flow diversion by greatly inhibiting flow into an aneurysm sac, causing its gradual shrinkage and occlusion, while still providing diminished but sufficient flow to maintain patency of side branches.
As illustrated in
With particular reference to
With particular reference to
In use, the stent-like body (with a closed cell design) comprised of the welded wire elements 205 make the filter self-centering within the interior vena cava. In addition, the perforated graft material of the base layer 215 is positioned to accommodate blood flow and otherwise trap thromboemboli from the pelvis and/or lower extremities that could otherwise cause a fatal pulmonary embolus if it reached the lungs. Such an IVC filter 200 may be advantageous since PTE (pulmonary thromboemboli) is currently the third leading cause of death in the United States.
In cases of extremely tortuous great vessel anatomy of the thoracic aortic arch (such as in the elderly and hypertensive), proximal access within the innominate or left common carotid artery could be established with a stiffer (e.g., ALZ) 7-F coronary guiding catheter, and then an approximately 2.8-F delivery microcatheter can be guided through the high-grade ICA stenosis over a 0.014″ wire. This wire may then be removed and replaced with the anchor-filter device that would then be deployed in the upper cervical ICA. Here it would stabilize the working wire and then permit easier, more rapid catheterizations in thoracic arch tortuous anatomy by means of a bi- or tri-axial catheter system, and may potentially also be useful to prevent distal grumous embolization during angioplasty and stenting of stenotic coronary bypass grafts. Once debris are captured at the conclusion of PTA and stenting, the filter device is re-captured by advancing an approximately 2.8 F recovery catheter over the working wire (which was used to also introduce PTA balloon catheters and stent devices) and collapsing the filter.
In still other embodiments, with reference to
The proximal end 415 of the wire mesh frame comprising wire elements 405 is mounted to a flexible hypotube 420 having an inner diameter of approximately 0.014″ or any other inner diameter suitable to allow the injection of particles (e.g., Biospheres, polyvinyl alcohol particles, Y90Therasphere particles) for radioembolization. In the case of radioembolization, backflow of the injected particles from the intra-arterial point of embolization may cause the particles to flow into a vital collateral channel serving the small bowel or stomach (e.g., the right gastric artery—in this case the radioactive Y90 particles could induce a nonhealing ulcer of the gastric mucosa). To avoid such problematic backflow, the proximal end 415 of the wire mesh stent has a conical shape and the perforations 425 on the graft material of the base layer 410 are appropriately sized to allow antegrade flow within the target vessel 430, but not to allow the backflow of injected particles, thus avoiding nontarget embolization into more proximal branch or collateral vessels. As illustrated in
The flow diversion device 500 includes an ultra-thin base layer 535 of graft material, such as polytetrafluoroethylene (PTFE), or other suitable graft fabric that surrounds at least a portion of the stent frame 510, with the base layer 535 including a plurality of perforations/pores 540 formed thereon to help control blood flow to the treatment site. Preferably, the base layer 535 is positioned on a substantially central portion of the stent frame 510, leaving the proximal and distal ends 525, 530 free of the base layer 535. As is explained in additional detail below, the base layer 535 inhibits or reduces blood flow therethrough due to the relatively small size of the perforations 540, but the openness of the stent frame 510 and the proximal and distal ends 525, 530 allows for increased blood flow to large side branches 600 that may be adjacent the treatment site of the aneurysm 555. In some embodiments, a portion of the boundary 545 of the base layer 535 may include radiopaque markers/material 550 to allow an operator to precisely place the stent frame 510 at a particular treatment site and to ensure that blood flow away is directed away from the aneurysm 555 while also directing sufficient blood flow to large side branches adjacent the aneurysm 555 as further described in detail below with reference to
In some embodiments, the flow diversion device 500 may include an anchor stent 560 attached to a guidewire 565 and extending forwardly from the distal end 530 of the stent frame 510. With reference to
In one example deployment process, the guidewire 590 is held stationary while the catheter 580 is retracted, with the anchor stent 560 helping retain the flow diversion device 500 in position at the target site. With reference to
When the treatment is complete and the flow diversion device 500 is ready for removal, the flow diversion device 500 may be resheathed by advancing the catheter 580 toward the proximal end 525 of the stent frame 510. As the catheter 580 moves forward, the flow diversion device 500 collapses into the catheter 580. Once the entire device 500 is sheathed in the catheter 580, the catheter 580, together with the device 500, may be removed.
It is intended that subject matter disclosed in any one portion herein can be combined with the subject matter of one or more other portions herein as long as such combinations are not mutually exclusive or inoperable. In addition, many variations, enhancements and modifications of the concepts described herein are possible.
The terms and descriptions used above are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations can be made to the details of the above-described embodiments without departing from the underlying principles of the invention.
21. A flow diversion device comprising:
- a tubular wire stent frame formed from a plurality of wire elements, each wire element in the plurality of wire elements having a zig-zag pattern shape, wherein adjacent wire elements form a plurality of junctions, and wherein a first set of the plurality of junctions are coupled together and a second set of the plurality of junctions are not coupled together; and
- a base layer attached to the wire stent frame and surrounding at least a central portion of the tubular wire stent, the base layer formed of a porous graft material and having a plurality of perforations formed therethrough in a predetermined spaced-apart pattern.
22. The flow diversion device of claim 21, wherein the plurality of perforations are incisions.
23. The flow diversion device of claim 22, wherein the incisions are half-circles.
24. The flow diversion device of claim 21, wherein the plurality of junctions formed between adjacent wire elements are alternately coupled.
25. The flow diversion device of claim 21, wherein the plurality of junctions are formed along a radial direction of the tubular wire stent frame.
26. The flow diversion device of claim 21, where a distal portion and a proximal portion of the tubular wire stent frame are free of the base layer.
27. The flow diversion device of claim 26, wherein the plurality of wire elements form a plurality of diamond shapes along the longitudinal direction of the tubular wire stent frame, and wherein at least 1½ diamonds of the distal portion and the proximal portion of the tubular wire stent frame are free of the base layer.
28. The flow diversion device of claim 21, wherein the wire stent frame supports the base layer in an open condition, and wherein the plurality of perforations prevent excess billowing of the base layer in the open condition while blood flows through the flow diversion device.
29. The flow diversion device of claim 21, further comprising a jacket attached to and surrounding the base layer.
30. The flow diversion device of claim 21, wherein a proximal end and a distal end of the wire stent frame further comprise a radiopaque marker.
31. A flow diversion device comprising:
- a tubular wire stent frame formed from a plurality of wire elements, each wire element in the plurality of wire elements having a zig-zag pattern; and
- a base layer attached to the wire stent frame and surrounding at least a portion thereof, the base layer formed or porous graft material having a plurality of perforations formed therethrough,
- wherein the wire stent frame supports the base layer in an open condition, and
- wherein the plurality of perforations prevent excess billowing of the base layer in the open condition while blood flows through the flow diversion device.
32. The flow diversion device of claim 31, wherein the plurality of wire elements form a plurality of diamond shapes along the longitudinal direction of the tubular wire stent frame, and wherein at least 1½ diamonds of the distal portion and the proximal portion of the tubular wire stent frame are free of the base layer.
33. The flow diversion device of claim 31, wherein the plurality of perforations are incisions.
34. The flow diversion device of claim 33, wherein the incisions are half-circles.
35. The flow diversion device of claim 31, further comprising an anchor stent attached to the wire stent frame.
36. The flow diversion device of claim 35, wherein the anchor stent is attached to a guidewire and extends from a distal end of the wire stent frame.
37. The flow diversion device of claim 36, wherein the anchor stent further comprises a plurality of wire elements, each wire element in the plurality of wire elements having a zig-zag pattern, and a plurality of connector struts that couple the plurality of wire elements to the guidewire.
38. The flow diversion device of claim 37, wherein the anchor stent further comprises a plurality of radiopaque markers on an end opposite the connector struts.
Filed: Jul 9, 2018
Publication Date: Feb 14, 2019
Inventor: GEORGE P. TEITELBAUM
Application Number: 16/029,939