Non-planar heating chamber detachment mechanism of an implantable vaso-occluding device delivery system

A delivery system for an implantable vaso-occluding device. A non-planar heating chamber is disposed proximate to a distal end of an advancing member. Protruding from an interior surface of the non-planar heating chamber is a detachment fiber made from a polymeric material and having a closed distal end. At least one heating element is disposed on the interior surface of the non-planar heating chamber to produce sufficient heat to sever the detachment fiber. An articulation point is established between the vaso-occluding device and the delivery system. The vaso-occluding device remains at all times substantially self-centered while being advanced.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention is directed to a delivery system for an implantable vaso-occluding device. In particular, the present invention relates to a non-planar heating chamber detachment mechanism using heat energy to release a detachment fiber securing the delivery system to the vaso-occluding device.

Description of Related Art

Embolization is a nonsurgical, minimally invasive procedure that selectively occludes (e.g., deliberately blocks) a blood vessel by purposely introducing an occluding device (e.g., an embolic coil) into the blood vessel. It is now commonplace to use catheter delivery systems for positioning and deploying such occluding devices, such as dilation balloons, stents and embolic coils, in the vasculature of the human body for treating endovascular diseases such as blocked arteries and aneurysms. Occluding devices are particularly useful in treating areas where traditional operational procedures are impossible or pose a great risk to the patient, for example in the treatment of aneurysms in intracranial blood vessels. Due to the delicate tissue surrounding intracranial blood vessels, especially for example brain tissue, it is very difficult and often risky to perform surgical procedures to treat defects of intracranial blood vessels.

Typically, these procedures involve inserting the distal end of a delivery catheter into the vasculature of a patient and guiding it through the vasculature to a predetermined delivery site. A vascular occlusion device, such as an embolic coil, is attached to the end of a delivery member which pushes the occlusion device through the catheter and out of the distal end of the catheter at a desired delivery site. Some of the problems that have been associated with these procedures relate to the accuracy of occlusion device placement. For example, the force employed to eject the occlusion device from the delivery catheter may cause the occlusion device to over shoot the predetermined site or dislodge previously deployed occlusion devices. Also, once the occlusion device is pushed out of the distal end of the catheter, the occlusion device cannot be retracted and may migrate to an undesired location. Often, retrieving and repositioning the occlusion device requires a separate procedure and has the potential to expose the patient to additional risk.

Once properly navigated through the vasculature of the patient to the target treatment site, the embolic coil is detached from its delivery system. Conventional forms of detachment have been used to sever the occluding device from its delivery system. Several known methods of detachment include electrical heating, mechanical interference or hydraulic and electrolytic detachment. Each of these conventional detachment mechanisms suffer from one or more disadvantages such as large stiff regions, inconsistent detachment of the occlusion device from its delivery system and/or extended detachment duration.

It is therefore desirable to develop an improved electrical heating detachment system and method for a vascular occluding device.

SUMMARY OF THE INVENTION

An aspect of the present invention relates to an improved electrically heated detachment system for an implantable vaso-occluding device that is reduced in size so that it may be used in the brain or other small target sites of the body to be treated.

While another aspect of the present invention is directed to an improved electrically heated detachment mechanism for an occluding device including a non-planar chamber for heating and releasing the detachment fiber.

Still a further aspect of the present invention is directed to a delivery system for an implantable vaso-occluding device, wherein the delivery system includes an advancing member having a distal end and an opposite proximal end. A non planar heating chamber is disposed proximate to the distal end of the advancing member, wherein the non-planar heating chamber has an interior surface facing away from the distal end of the advancing member and an opposite exterior surface facing the distal end of the advancing member. Protruding from the interior surface of the non-planar heating chamber is a detachment fiber made from a polymeric material and having a closed distal end. At least one heating element is disposed on the interior surface of the non-planar heating chamber to produce heat for releasing the detachment fiber.

Another aspect of the present invention is directed to a method for assembling a delivery system for an implantable vaso-occluding device as described in the preceding paragraph. The at least one heating element is positioned on the interior surface of the non-planar heating chamber. Then exterior surface of the non-planar heating chamber is secured to the distal end of the advancing member. One of two terminating free ends of the detachment fiber is threaded through a securing member disposed on the vaso-occluding device until the securing member reaches the closed distal end of the detachment fiber. The two terminating free ends of the detachment fiber along with the vaso-occluding device are secured to the distal end of the advancing member with the non-planar heating chamber disposed therebetween. The at least one heating element disposed on the interior surface of the non-planar heating chamber produces heat for releasing the detachment fiber.

While yet another aspect of the present invention relates to a method for positioning an implantable vaso-occluding device at a target site within a blood vessel using a delivery system as previously described above. Using a delivery catheter, the delivery system is introduced into the blood vessel. The delivery catheter is then advanced through the blood vessel to the target site. Once at the target site in the blood vessel, the advancing member is deployed to project the vaso-occluding device from the delivery catheter. The at least one heating element is energized by a power source to produce heat energy sufficient to sever the detachment fiber thereby freeing the vaso-occlusive device at the target site in the blood vessel. Lastly, the delivery catheter and the advancing member disposed therein are extracted from the blood vessel while maintaining the vaso-occlusive device located at the target site in the blood vessel.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is an exploded view of an implantable vaso-occluding device delivery system with a non-planar heat chamber detachment mechanism in accordance with the present invention. Delivery system100includes an advancing member or pusher10having a proximal end5and a distal end15. By way of illustrative example, the delivery system100illustrated in the figures and described herein is a catheter-based delivery system. An implantable vaso-occluding device60, such as an embolic coil is attached to the distal end15of advancing member10via a polymer detachment fiber45. It is to be noted, that the present inventive delivery system is not limited to that of an embolic coil and may be used with other implantable vaso-occluding devices.

Advancing member10is of sufficiently small diameter to fit within the lumen of the delivery catheter and preferably having sufficient columnar strength to transmit axial force distally while simultaneously be sufficiently flexible to navigate tortuous anatomies. The advancing member10may, but need not have, one or more of the following attributes: a hollow passageway; be electrically conductive; comprise composite layers or non-homogeneous material properties. Proximate the distal end15of the advancing member10is a non-planar heating chamber, bowl or dish20. By way of illustrative example, the heating chamber20illustrated in the figures has a parabolic shape. Any non-planar shape is contemplated and within the scope of the present invention such as, but not limited to, elliptical or conical in shape. When viewed from the distal end15of the advancing member10the heating chamber20forms a concave, bowl or non-planar dish shape. An interior surface of the heating chamber20faces away from the distal end15of the advancing member10, while its exterior surface faces the distal end15of the advancing member10. Substantially centered and protruding from the exterior surface of the bowl or non-planar dish of the heating chamber20is a cylindrical tube or neck25. Heating chamber20has a central opening23defined therein and extending longitudinally the entire length of neck25to form a passageway or channel therethrough. Extending radially outward from the central opening23of the heating chamber20is an enlarged non-planar collar40. The outer diameter of the non-planar collar40is greater than the outer diameter of neck25, while the outer diameter of the neck25is preferably sufficiently small to be received within an inner diameter of the distal end15of the advancing member10. Neck25may be secured within the advancing member in any number of ways including, but not limited to the following: a press-fit; mechanically (e.g., via mating threads); or via adhesive.

One or more boles or openings30may be defined longitudinally through the non-planar collar40for introducing/threading/weaving one or more electrical heater elements/wires50longitudinally therethrough the advancing member10backwards towards its proximal end5. In the exemplary embodiment illustrated in the figures, the non-planar collar40has five holes or openings30, but this may be varied, as desired, to include any number of openings. Multiple openings30allow the number and arrangement of the heating wires or elements50on the heating chamber20to be adapted or reconfigured. Alternatively, the openings30may be eliminated altogether or reduced in number whereby the heating wires/elements50may be permanently attached to or embedded in the interior surface of the heating chamber20. This is advantageous in that it allows for a greater number of heating elements without restriction of quantity of openings defined in the planar collar40. Furthermore, eliminating or reducing the number of openings defined in the planar collar40provides a greater undisturbed surface area to focus heat.

The number of heating wires/elements50may be selected, as desired, with at least one or more heating wires/elements50. Two electrical heating wires/elements50will generate heat at two different locations along the detachment fiber45. Three electrical heating wires/elements50produce heat at three different locations along the detachment fiber45, and so on. More than one heating wire/element50provides greater heat energy and/or the ability to provide heat energy at multiple locations at different times (e.g., for two detachment fibers45). Furthermore, more than one heating wire/element50also advantageously insures reliable embolic coil separation or detachment at the target site. Greater heat energy may be retained by reducing the opening angle the angle subtended by two radii drawn from the midpoint of the central opening23to the outer edge of the non-planar collar 180° separation from one another) and/or depth (i.e., distance from the midpoint of the central opening23to an outer edge of the non-planar collar40) of the non-planar heating chamber20.

Referring to the exemplary embodiment shown inFIG. 1, the respective free ends50aof a U-shaped heating wire/element50are received within two openings30(preferably two adjacent openings) defined longitudinally through the non-planar collar40. Free ends50aof the heating wire50preferably extend exterior of neck25through at least a portion, if not the complete longitudinal length, of the advancing member10towards its proximal end5and are electrically connected via electrical wires or leads to a power supply55providing electrical energy exciting the heating wire thereby producing heat. Preferably, the power supply is external to the human body; however, a battery (rechargeable or non-rechargeable) internal to the human body (e.g., disposed within the delivery system100itself) may alternatively be used. The type, location (external or internal to the human body), number of power supply may be varied, as desired, so long as energy is provided to excite the heating wire/element50thereby generating heat. Energy supplied to each of the heating wires/elements50may be substantially the same, or otherwise, may be varied, as desired, for each independent heating wire/element may be connected to respective different power supplies.

Advancing member10is secured to a vaso-occlusive device60(e.g., embolic coil) via a detachment fiber45, preferably made of a polymeric material such as polyethylene, polypropylene or any other relatively thinly extrudable polymer that is able to be melted by heat. The exemplary detachment fiber45illustrated is a U-shaped fiber having an enlarged closed distal end46secured or linked to the embolic coil60. For example, one of the free ends45aof the detachment fiber45is threaded through a securing member65(e.g., ring) disposed on the proximal end of the embolic coil60and secured therein by the enlarged closed end46. Free ends45aof the detachment fiber45extend back through the opening23and advancing member10towards its proximal end5, while the enlarged closed end46engages with thereby preventing its passage through the central opening23. The detachment fiber45may be secured within the passageway/lumen of advancing member10by mechanical means, friction or adhesive.

The non-planar shape of the hating chamber has numerous advantages, for instance: (i) providing an articulation point between the proximal end of the occluding device and the distal end of the delivery system (seeFIG. 5), (ii) self-centering at all times of the occluding device is maintained while being delivered/advanced through the tortuous human anatomy; and (iii) maintaining physical contact at all times between the detachment fiber and heating elements/wires so as to minimize energy required to detach the occluding device from the delivery system.

The present invention detachment mechanism for an implantable vaso-occluding device delivery system is suitable for treatment of a diverse array of medical disorders throughout the body. However, due to difficulties associated with treating disorders of the brain, the present inventive detachment system is particularly beneficial due to the minimized expended energy required to melt/sever the detachment fiber that minimizes damage to surrounding brain tissue.

In operation, the vaso-occluding device60to (e.g., embolic coil) is assembled/installed on the advancing member10. One of the free ends45aof the detachment fiber45is passed through the securing member65(e.g., ring) disposed proximate the proximal end of the embolic coil60. For instance, the detachment fiber45is threaded, looped, hooked or otherwise passes through the ring or other mechanical securing device65of the embolic coil60secured thereon by the enlarged closed end46. The free ends45aof the detachment fiber45are inserted into the opening23and through the advancing member10until its enlarged closed, end46rests in physical contact against without entering the opening23. The advancing member10and embolic coil60secured thereto together are introduced into a delivery catheter95. Once assembled, the delivery catheter95together with the advancing member and embolic coil is introduced into the body and traverses through the blood vessel to a target site. When the occluding device60reaches the target site within the body, the advancing member10is deployed to push the embolic coil60out from the delivery catheter95at the target site. The heating wire50is then energized by the power source55(either internal or external to the body) causing the detachment fiber45to melt or sever. The severed detachment fiber45allows the occluding device60to free itself from the advancing member10and remain positioned at the target site in the blood vessel. The delivery catheter95and advancing member10may then be withdrawn from the body while the embolic coil remains in place at the target site.

Every issued patent, pending patent application, publication, journal article, book or any other reference cited herein is each incorporated by reference in their entirety.