Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent structure
Reexamination Certificate
1996-06-21
2001-02-20
Thaler, Michael H. (Department: 3731)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent structure
C623S017120, C606S198000, C606S108000
Reexamination Certificate
active
06190402
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates broadly to an insitu formable and self-forming intravascular flow modifier (IFM) and/or stent and the delivery and deployment of the IFM to a defect in a vessel. More particularly, the invention relates to an IFM that may be deployed in previously inaccessible vessels to current generation IFMs or stents due to the nearly linear pre-deployed configuration of the IFM and a method for controlling the final placement and deployed configuration of the IFM within a pre-selected segment of the vessel. The present invention is particularly suited but not limited to use as an intracranial IFM and method for deploying the IFM in a vessel.
2. Description of the Related Art
Most related art devices cannot be deployed in intracranial vessels. Even the devices having a pre-deployed configuration with a substantially reduced diameter compared to their respective deployed configuration are typically too large and too stiff to navigate the tight turn of the carotid artery and other small vessels of the body with torturous turns.
U.S. Pat. No. 4,512,338 issued to Balko et al. discloses a process of deploying a memory metal coil across a defect in a vessel. The coil is elongated prior to deployment and warmed within the vessel to substantially revert back to its original coil form.
None of the related art, including Balko et al., discloses IFM or a stent having the radial strength associated with multiple coils within one another with the capability of deploying the IFM or stent with a deployed configuration variably controlled by the relative movement of the strand forming the IFM or stent and a catheter through which the strand extends.
A need exists for an IFM, a catheter and IFM assembly, and a method for deploying the IFM which can provide a coil-in-coil IFS of various deployed configurations in previously inaccessible vessels according to the judgement of the physician at the time of deployment.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an IFM, a catheter and IFM assembly, and a method for deploying the IFM that overcomes the limitations and disadvantages of the related art.
An advantage of the present invention is its simple design that is nevertheless capable of providing an IFM that may be readily deployed in various configurations according to the specific vessel defect to alter the flow dynamics of the vessel, to keep an embolus deployed in a wide neck aneurysm in the aneurysm, or to support and strengthen the vessel.
Another advantage is that the IFM can access vessels through a unique catheter assembly and associated technique for delivering the IFM in a manner previously unavailable in the related art.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and other advantages of the invention will be realized and attained by the IFM, the catheter and IFM assembly, and the method for deploying the IFM particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages in accordance with the purpose of the invention, as embodied and broadly described, the invention comprises an outer layer formed of a strand, which is configured as a longitudinally oriented coil of adjacent helical loops extending between a first end and a second end of the outer layer. The outer layer is secured in the vessel by at least some of the helical loops pressing against a portion of the interior surface of the vessel. The invention also includes an inner layer formed of a strand, which is configured as a longitudinally oriented coil of adjacent helical loops extending between a first end and a second end of the inner layer. At least a portion of the outer layer surrounds at least a portion of the inner layer so that at least some of the loops of the outer layer overlap and contact at least some of the loops of the inner layer.
Preferably, the strand of the outer layer and the inner layer is a continuous strand, which is more preferably formed of or coated by a biocompatible material. Preferably, the strands of the outer and inner layers are formed of a high shape memory alloy, such as Nitinol alloy. The strand of the outer layer and the strand of the inner layer preferably have a circular, oval, rectangle, or triangular cross-section.
In one embodiment of the invention, the second end of the outer layer is anchored proximal to the first end of the inner layer. The second end of the outer layer preferably joins the first end of the inner layer. In another embodiment of the invention, the first end of the outer layer attaches to the second end of the inner layer so that the continuous strand forms a loop.
The first end of the outer layer and the second end of the inner layer may include means for inhibiting the wire strand from penetrating through the interior surface of the vessel, such as a loop on the ends. The first end of the outer layer and the second end of the inner layer are preferably distal ends relative to an insertion point into the vessel. The second end of the outer layer and the first end of the inner layer are preferably proximal ends relative to an insertion point into the vessel. Alternatively, the respective ends of the outer and inner layers may be reversed relative to the insertion point into the vessel depending upon the method used to deploy the IFM.
The preferred helical loops of the outer and inner layers are substantially circular. Both the helical loops of the outer and inner layers wind in a predetermined direction. Preferably, the rotation of the helical loops of the outer and inner layers is in the same direction but with the helical loops of the outer layer having a alpha helix and the helical loops of the inner layer having a beta helix. Of course, the outer layer may have the beta helix and the inner layer may have the alpha helix. Preferably, the number of helical loops of the outer layer is N, where N is at least two, and the number of the helical loops of the inner layer is M, where M is at least two.
In another embodiment of the invention, the outer layer is divided into at least a first end portion, a middle portion, and second end portion along the longitudinally oriented coil. The first end, middle, and second end portions each have a pitch. The pitch of the middle portion may be smaller than the pitch of the first end and second end portions. Alternatively, the pitch of the middle portion may be larger than the pitch of the first end and second end portions. The pitch of the first and second end portions preferably provides a gap between the helical loops of between 3 and 7 mm (0.118 and 0.276 inches), while the pitch of the middle portion preferably provides a gap between the helical loops of between 0.5 and 3 mm (0.020 and 0.118 inches).
The diameter of the wire strand of the first end and second end portions of the outer layer may be smaller than the diameter of the wire strand of the middle portion. A preferred diameter of the wire strand of the outer layer is no greater than 0.020 inches. A more preferred diameter of the wire strand of the outer layer is between 0.00025 and 0.006 inches. The diameter of the wire strand of the outer layer comprising the first end and second end portions is more preferably between 0.001 and 0.002 inches, and the diameter of the wire strand comprising the middle portion is more preferably between 0.003 and 0.004 inches.
As with the outer layer, the inner layer may be divided into at least a first end portion, a middle portion, and a second end portion along the longitudinally oriented coil. The pitch of the middle portion may be smaller than the pitch of the first end and second end portions. Alternatively, the pitch of the middle portion may be larger than the pitch of the first end and second end portions. The pitch of the first and second end portions preferably provides a gap betw
Horton Joseph A.
Vincent Diana Joan
Fulwider Patton Lee & Utecht LLP
MUSC Foundation for Research Development
Thaler Michael H.
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