Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
1999-02-22
2001-01-30
Dawson, Glenn K. (Department: 3763)
Surgery
Instruments
Internal pressure applicator
C606S001000, C606S151000, C606S213000
Reexamination Certificate
active
06179857
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an embolic coil which may be placed at a preselected location within a vessel of the human body, and more particularly, relates to an embolic coil which is stretch resistant but which may be modified to vary the stiffness, or flexibility, of the coil.
2. Description of the Prior Art
For many years flexible catheters have been used to place various devices within the vessels of the human body. Such devices include dilatation balloons, radiopaque fluids, liquid medications and various types of occlusion devices such as balloons and embolic coils. Examples of such catheter devices are disclosed in U.S. Pat. No. 5,108,407, entitled “Method And Apparatus For Placement Of An Embolic Coil”; U.S. Pat. No. 5,122,136, entitled, “Endovascular Electrolytically Detachable Guidewire Tip For The Electroformation Of Thrombus In Arteries, Veins, Aneurysms, Vascular Malformations And Arteriovenous Fistulas.” These patents disclose devices for delivering embolic coils to preselected position within vessel of the human body in order to treat aneurysms or alternatively to occlude the blood vessel at the particular location.
Coils which are placed in vessels may take the form of helically wound coils, or alternatively, may be random wound coils, coils wound within other coils or many other such coil configurations. Examples of various coil configurations are disclosed in U.S. Pat. No. 5,334,210, entitled, “Vascular Occlusion Assembly; U.S. Pat. No. 5,382,259, entitled, “Vasoocclusion Coil With Attached Tubular Woven Or Braided Fibrous Coverings.” Embolic coils are generally formed of a radiopaque metallic materials, such as platinum, gold, tungsten or alloys of these metals. Often times several coils are placed at a given location in order to occlude the flow of blood through the vessel by promoting thrombus formation at the particular location.
In the past, the proximal end of embolic coils have been placed within the distal end of the catheter and when the distal end of the catheter is properly positioned the coil may then be pushed out of the end of the catheter with, for example a guidewire, to release the coil at the desired location. This procedure of placement of the embolic coil is conducted under fluoroscopic visualization such that the movement of the coil through the vasculature of the body may be monitored and the coil may be placed in the desired location. With these placements systems there is very little control over the exact placement of the coil since the coil may be ejected to a position some distance beyond the end of the catheter. As is apparent, with these latter systems, when the coil has been released from the catheter it is difficult, if not impossible, to retrieve the coil or to reposition the coil.
Numerous procedures have been developed to enable more accurate positioning of coils within a vessel. Still another such procedure involves the use of a glue or solder for attaching the embolic coil to a guidewire which, is in turn, placed within a flexible catheter for positioning the coil within the vessel at a preselected position. Once the coil is at the desired position, the coil is restrained by the catheter and the guidewire is pulled from the proximal end of the catheter to thereby cause the coil to be detached from the guidewire and released from the catheter system. Such a coil positioning system is disclosed in U.S. Pat. No. 5,263,964, entitled, “Coaxial Traction Detachment Apparatus And Method.”
Another coil positioning system utilizes a catheter having a socket at the distal end of the catheter for retaining a ball which is bonded to the proximal end of the coil. The ball, which is larger in diameter than the outside diameter of the coil, is placed in a socket within the lumen at the distal end of the catheter and the catheter is then moved into a vessel in order to place the coil at a desired position. Once the position is reached, a pusher wire with a piston at the end thereof is pushed distally from the proximal end of the catheter to thereby push the ball out of the socket in order to thereby release the coil at the desired position. Such a system is disclosed in U.S. Pat. No. 5,350,397, entitled, “Axially Detachable Embolic Coil Assembly.” One problem with this type of coil placement system which utilizes a pusher wire which extends through the entire length of the catheter and which is sufficiently stiff to push an attachment ball out of engagement with the socket at the distal end of the catheter is that the pusher wire inherently causes the catheter to be too stiff with the result that it is very difficult to guide the catheter through the vasculature of the body.
Another method for placing an embolic coil is that of utilizing a heat releasable adhesive bond for retaining the coil at the distal end of the catheter. One such system uses laser energy which is transmitted through a fiber optic cable in order to apply heat to the adhesive bond in order to release the coil from the end of the catheter. Such a method is disclosed in U.S. Pat. No. 5,108,407, entitled, “Method And Apparatus For Placement Of An Embolic Coil.” Such a system also suffers from the problem of having a separate element which extends throughout the length of the catheter with the resulting stiffness of the catheter.
Still another method for placing an embolic coil is disclosed in co-pending U.S. patent application Ser. No. 09/177,848, entitled “Embolic Coil Hydraulic Deployment System,” filed on Oct. 21, 1998 and assigned to the same assignee as the present patent application. This patent application discloses the use of fluid pressure which is applied to the distal tip of the catheter for expanding the lumen in order to release the embolic coil.
Various embolic coil designs have been proposed for use with coil deployment systems such as the stretch resistant vaso-occlusive coil disclosed in U.S. Pat. No. 5,853,418, entitled “Stretch Resistant Vaso-occlusive Coils,” which discloses a helically wound coil having a polymeric stretch resisting member extending through the lumen of the coil and fixedly attached to both the distal end and the proximal end of the coil. While the stretch resisting member prevents the coil from being stretched during use, this member which extends throughout the length of the coil tends to significantly reduce the flexibility of the coil. This reduced flexibility may present problems because in order to place vaso-occlusive coils into a desired location it is very important that the coil be very flexible.
SUMMARY OF THE INVENTION
The present invention is directed toward a vascular occlusive coil which may be placed at a preselected site within the vasculature and which exhibits the property of being stretch resistant while at the same time being very flexible. The coil may also be modified to vary the stiffness of the coil while at the same time retaining the stretch resistant characteristics of the coil. These and other features result in a vaso-occlusive coil which overcomes problems associated with prior embolic coils.
Accordingly, the present invention is directed toward a vaso-occlusive device for placement within the vasculature and includes an elongated helically wound coil having a proximal end, a distal end and a lumen extending therethrough. The coil is preferably formed of a plurality of turns of wire having a diameter of between about 0.0002 and 0.008 inches and the coil has an overall diameter of between about 0.006 and 0.055 inches. Substantially all of the turns from the proximal end of the coil to the distal end of the coil are spot welded to adjacent turns such that the spot welded joints between adjacent turns form a straight line which extends in a direction parallel to the longitudinal axis of the lumen of the coil. Also, the terms may be connected by other methods, such as by glueing or attachment by wrapping with thread.
In accordance with another aspect of the present invention, substantially all of the turns from the proximal end of the coil to the dist
Diaz Roberto
Jones Donald K.
Naglreiter Brett E.
Collins Henry W.
Cordis Corporation
Dawson Glenn K.
Maynard Jennifer
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