TECHNICAL FIELD

The disclosure relates to embolic coils, as well as related methods and devices.

BACKGROUND

Therapeutic vascular occlusions (embolizations) are used to prevent or treat pathological conditions in situ. Embolic coils can be used to occlude vessels in a variety of medical applications. Delivery of embolic coils (e.g., through a catheter) can depend on the size and/or shape of the coils. Some embolic coils include fibers that can, for example, enhance thrombosis at a treatment site.

SUMMARY

In some systems, fibered coils can be placed in delivery catheters with fiber bundles oriented to facilitate delivery of the coil out of the catheter. In some coils, the distribution of the fiber bundles along the coil varies such that fiber bundle density, and thus column strength, is higher near the point at which deployment force is applied to the coil.

In one aspect, a system includes a catheter having a delivery end; and an embolic coil at least partially disposed within the catheter. The embolic coil includes a coil wire having an end fitting configured to releasably couple to an end fitting of a delivery wire, and a fiber bundle contacting the catheter, the fiber bundle having a first bundle end being attached to the coil wire and a second bundle end opposite the first bundle end. The fiber bundle is disposed such that a distance from the first bundle end to the delivery end of the catheter is less than a distance from the second bundle end to the delivery end of the catheter.

In some embodiments, the embolic coil comprises multiple fiber bundles contacting the catheter, each fiber bundle having first and second bundle ends, the first bundle end being attached to the coil wire, the second bundle end opposite the first bundle end, the fiber bundle being disposed such that a distance from the first bundle end of a specific fiber bundle to the delivery end of the catheter is less than a distance from the second bundle end of the specific fiber bundle to the delivery end of the catheter. In some cases, more fiber bundles are attached to a first half of the coil than are attached to a second half of the coil.

In some embodiments, the coil is disposed in the catheter such that the second half of the coil is between the first half of the coil and the delivery end of the catheter.

In some embodiments, spacing between adjacent fiber bundles increases with increasing distance from the end fitting of the coil wire.

In some embodiments, the fiber bundles are disposed in at least one group and the spacing between adjacent fiber bundles is constant within each group of the at least one group.

In some embodiments, each fiber bundle is attached to the coil wire at an attachment point and a first attachment point is circumferentially spaced apart from a second attachment point. In some cases, the attachment point of each fiber bundle is circumferentially spaced apart from the attachment points of adjacent fiber bundles.

In some embodiments, the fiber bundle comprises polyethylene terephthalate or nylon.

In some embodiments, wherein the coil wire has a diameter from 0.0075 inch to 0.015 inch.

In some embodiments, wherein the fiber bundle has a length from 0.025 inch to 0.125 inch.

In some embodiments, the coil wire comprises a metal.

In some embodiments, the system also includes a lubricant disposed within the catheter. In some cases, the lubricant is disposed on the fiber bundle.

In some embodiments, an inner surface of the catheter includes a material selected from the group consisting of polypropylene, polytetrafluoroethylene (PTFE), fluoroethylene polymer (FEP), low-density polyethylene (LDPE), high-density polyethylene (HDPE), nylon, Teflon®, and acrylic.

In one aspect, a coil includes: a coil wire having a first end, and opposite second end, and a midpoint located halfway between the first end and the second end; and multiple fiber bundles attached to the coil wire. More fiber bundles are attached to the coil wire between the first end and the midpoint than are attached to the coil wire between the second end and the midpoint. The coil is an embolic coil.

In some embodiments, spacing between adjacent fiber bundles increases with increasing distance from the first end of the coil.

In some embodiments, the fiber bundles are disposed in at least one group and the spacing between adjacent fiber bundles is constant within each group of the at least one group.

In some embodiments, the coil also includes a end fitting attached to the first end of the coil wire, the end fitting configured to releasably couple the embolic coil to a mating end fitting of a delivery wire.

In some embodiments, a proximal end of the coil wire is configured to provide an opposable surface configured for engagement of a pusher element.

In one aspect, a system includes: a catheter having a delivery end; a delivery wire with an end fitting; and an embolic coil disposed within the catheter, the embolic coil having a first half and a second half, the second half disposed between the first half and the delivery end of the catheter, the embolic coil including a coil wire and multiple fiber bundles contacting the catheter, the coil wire having an end fitting configured to releasably couple to the end fitting of the delivery wire and each fiber bundle extending from a first bundle end attached to the coil wire to a second bundle end opposite the first bundle end. A majority of the fiber bundles are angled such that a distance from the first bundle end of a specific fiber bundle to the delivery end of the catheter is less than a distance from the second bundle end of the specific fiber bundle to the delivery end of the catheter. More fiber bundles are attached to the first half of the embolic coil than are attached to a second half of the coil.

In some embodiments, spacing between adjacent fiber bundles increases with increasing distance from the end fitting of the coil wire.

In some embodiments, the fiber bundles are disposed in groups and the spacing between adjacent fiber bundles is constant within each group.

In some embodiments, each fiber bundle is attached to the coil wire at an attachment point and a first attachment point is circumferentially spaced apart from a second attachment point. In some cases, the attachment point of each fiber bundle is circumferentially spaced apart from the attachment points of adjacent fiber bundles.

In one aspect, a method includes: advancing a delivery sheath over a distal end of an embolic coil while applying tension to the embolic coil via a retaining device that is attached to the distal end of the embolic coil.

In some embodiments, the method also includes engaging fiber bundles extending from a first bundle end attached to the coil wire to a second bundle end with the sheath such that, for a majority of the fiber bundles, a distance from the first bundle end of a specific fiber bundle to a proximal end fitting of the embolic coil is greater than a distance from the second bundle end of the specific fiber bundle to the end fitting of the embolic coil. In some cases, the method also includes stopping advancement of the sheath after the distal end of the coil emerges from a delivery end of the sheath and before any of the fiber bundles emerge from the delivery end of the sheath. In some cases, the method also includes detaching the retaining device from the distal end of the coil. In some cases, the method also includes refining the distal end of the coil. In some cases, the method also includes withdrawing the distal end of the coil into the sheath.

In some embodiments, the method also includes stopping advancement of the catheter over the embolic coil before a proximal end of the coil enters the sheath. In some cases, the method also includes engaging an end fitting of a delivery wire with a proximal end fitting of the coil.

In some embodiments, the coils can exhibit relatively little friction during deployment.

In certain embodiments, the coils exhibit relatively high column strength near the point of application of deployment force at the proximal end of the coil.

Other features and advantages will be apparent from the description, drawings, and claims.

