# Patent

## Title
Apparatus and method for deployment of a therapeutic device using a catheter

## Abstract

The apparatus for deployment of an intravascular therapeutic device, includes an elongated, flexible pusher member and a therapeutic device connected to a severable portion of a first connector member mounted to the flexible pusher member with an elongated second connector member connected to the therapeutic device. The first connector member or second connector member may be capable of being broken by heat, and a heat source is provided for heating and breaking the first connector member or the second connector member to release the therapeutic device.

## Background
CROSS REFERENCES TO RELATED APPLICATIONS
This is a continuation of application Ser. No. 12/814,397 filed 11 Jun. 2010, now U.S. Pat. No. 8,298,256, which is a continuation of application Ser. No. 11/726,074 filed 21 Mar. 2007, now U.S. Pat. No. 7,740,637, which is a continuation-in-part of application Ser. No. 11/020,936, filed 22 Dec. 2004, now U.S. Pat. No. 7,198,613, which is a continuation of application Ser. No. 10/290,777, filed 7 Nov. 2002, now U.S. Pat. No. 6,966,892, which is a continuation of application Ser. No. 09/501,466, filed 9 Feb. 2000, now U.S. Pat. No. 6,478,773.


FIELD OF THE INVENTION
This invention relates generally to devices for intravascular interventional therapeutic treatment or vascular surgery for treatment of defects in the vasculature, and more particularly concerns a system and method for delivering intravascular interventional devices, such as for treatment of aneurysms.
BACKGROUND OF THE INVENTION
Vascular interventional devices such as vasoocclusive devices are typically placed within the vasculature of the human body by use of a catheter. Vascular interventional devices such as stents can be placed within an occluded vessel to facilitate blood flow through the vessel, and vasoocclusive devices are typically either placed within a blood vessel to block the flow of blood through the vessel by forming an embolus, or are placed within an aneurysm stemming from the vessel to form an embolus within the aneurysm. Stents can have a wide variety of configurations, but generally need to be placed and then released at a desired location within a blood vessel. Vasoocclusive devices used for these procedures can also have a wide variety of configurations, and aneurysms have been treated with external surgically placed clips, detachable vasoocclusive balloons and embolus generating vasoocclusive devices such as one or more vasoocclusive coils.
The delivery of such vasoocclusive devices have typically been accomplished by a variety of means, including via a catheter in which the device is pushed through an opening at the distal end of the catheter by a pusher to deploy the device. The vasoocclusive devices can be produced in such a way that they will pass through the lumen of a catheter in a linear shape and take on a complex shape as originally formed after being deployed into the area to be treated, such as an aneurysm.
One conventional releasable balloon catheter used to embolize vascular lesions has a tube portion made of a material such as a hydrophilic polymer, located between the catheter and the balloon, that can be melted by heating the tube, or can be dissolved in the blood when heated, and electrodes are provided for heating the tube. Another conventional technique for separating a balloon from a balloon catheter involves the melting and breaking of a connecting member between the balloon and the catheter body, when power is supplied to electrodes provided for heating the connecting member. When the connecting member is heated to temperatures of about 70° C. and slight tension is applied, the balloon can be separated from the main catheter body.
An implant delivery assembly is also known that is used for delivery of implants such as embolic coils, utilizing a shape memory decoupling mechanism activated when exposed to body temperature. A cooling solution is flushed through the catheter during introduction and placement of the implant in order to prevent premature release of the implant prior to the time that the implant is to be released. Another implant delivery assembly includes an electrical heating system for heating the coupling mechanism to a temperature at which the shape memory material returns to its original shape, to deploy the implant.
Another device is known in which a device to be implanted is detached by application of a high-frequency current which melts and severs a resin that is used to retain the device to be implanted until the device is to be deployed. In another known device, an electrolytically severable link is dissolved by activation of a power source electrically coupled to the electrolytically severable link to detach the device to be implanted.
In another conventional technique, a conductive guidewire delivers a high frequency current through the guidewire to melt and sever a joint to detach an implanted device from the guidewire. The patient is grounded during the procedure, and current is introduced via the guidewire, rather than with a two way current path.
Such devices that release the interventional device by melting or dissolving the intermediate section between the catheter tip and implanted device may cause thermal damage of surrounding tissues during detachment that can cause embolization in the bloodstream, and may also potentially release undesirable particles of materials into the bloodstream that can also cause embolization in the bloodstream. There is therefore a need for a precise method of deploying therapeutic interventional devices without compromising the position of the implant, without causing thermal damage to surrounding tissues, and without releasing undesirable particles of materials into the bloodstream and risking the formation of emboli in the bloodstream. The present invention meets these and other needs.
SUMMARY OF THE INVENTION
Briefly, and in general terms, the present invention provides for an apparatus for deployment of an intravascular therapeutic device, such as a vasoocclusive device, a microcoil, at least one electrode, a stent, or a coated coil, for example, using an elongated, flexible pusher member. The therapeutic device is connected to a first connector member mounted to the flexible pusher member with an elongated second connector member connected between the first connector member and the therapeutic device. At least one of the first and second connector members includes a severable portion that is capable of being severed, such as by melting or degradation, by heat. A heat source is provided for heating and breaking the severable portion of the first or second connector member to release the therapeutic device. The first connector member may be formed from a molded thermoplastic material, such as high density polyethylene, and the elongated second connector member may be a connector fiber, or a ribbon, for example. The elongated second connector member may also be formed from a thermoplastic material, such as high density polyethylene. The heat source is advantageously contained substantially within the pusher member, which provides a sufficient amount of thermal insulation to eliminate the potential for thermal damage to surrounding tissues during detachment of the therapeutic device. Since the severable first connecting member is heated and broken at a location fully contained within the pusher member, the potential for releasing undesirable particles of materials into the bloodstream and consequent embolization in the bloodstream is virtually eliminated.
The invention accordingly provides for an apparatus for release and deployment of a therapeutic device within the vasculature of a patient, the apparatus including an elongated, flexible pusher member having an interior lumen, a first connector member mounted to the elongated, flexible pusher member. In one aspect, the first connector member may have a severable portion capable of being broken by heating disposed within the elongated, flexible pusher member. An elongated second connector member is connected to the therapeutic device and detachably connected to the first connector member. The elongated second connector member thereby connects the therapeutic device to the pusher member for placement of the therapeutic device within the vasculature, and in one aspect, the elongated second connector member may have a severable portion capable of being broken by heating disposed within the elongated, flexible pusher member.
In one aspect, a heat source may be disposed in the interior lumen of the pusher member adjacent to the first connector member for heating the severable portion of the first connector member to cause the severable portion of the first connector member to break and release the elongated second connector member for detaching and deploying the therapeutic device from the flexible pusher member when a desired placement of the therapeutic device within the vasculature is achieved.
In another aspect, the first connector member may be formed from a molded thermoplastic, such as high density polyethylene, for example. The first connector member may be molded in the form of a rod extending across the interior diameter of the interior lumen of the pusher member, a post, a ring, or other similar suitable configurations. In another aspect, the heat source may include an electrical resistance heat source coil. Alternatively, the heat source may include an induction ring, and may be included in the first connector member, for severing the elongated second connector member. A control unit is typically connected to the heat source to supply electrical current to the heat source. The flexible pusher member typically includes a heat insulating shaft having an entry port communicating with the interior lumen of the pusher member, and the heat source is disposed in the interior lumen of the pusher member adjacent to the entry port. The flexible pusher member has a distal tip, and in one aspect, the heat source may be spaced apart from the distal tip of the flexible pusher member.
In other aspects, the elongated second connector member may be a connector fiber, or may be a ribbon. The therapeutic device may be a vasoocclusive device, a microcoil, at least one electrode, a stent, or a coated coil, for example.
These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings, which illustrate by way of example the features of the invention.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top sectional view of a first embodiment of the apparatus for release and deployment of a therapeutic device.
FIG. 2 is a side sectional view of the apparatus of FIG. 1.
FIG. 3 is a top sectional view of a second embodiment of the apparatus for release and deployment of a therapeutic device.
FIG. 4 is a top sectional view of a third embodiment of the apparatus for release and deployment of a therapeutic device.
FIG. 5 is a side sectional view of the apparatus of FIG. 1, illustrating release of the therapeutic device.
FIG. 6 is a side sectional view of the apparatus of FIG. 3, illustrating release of the therapeutic device.
FIG. 7 is a side sectional view of the apparatus of FIG. 4, illustrating release of the therapeutic device.
FIG. 8 is a top sectional view of a fourth embodiment of the apparatus for release and deployment of a therapeutic device.
FIG. 9 is a side sectional view of the apparatus of FIG. 8.
FIG. 10 is a side sectional view of the apparatus of FIG. 8, illustrating release of the therapeutic device.



DETAILED DESCRIPTION OF THE INVENTION
While vasoocclusive devices have conventionally been delivered to a portion of a patient's vasculature to be treated through a delivery catheter by means of a pusher device, such conventional methods can involve separation of the vasoocclusive device from the pusher device in ways that result in injury to the vasculature, such as by causing thermal damage of surrounding tissues during detachment that can cause embolization in the bloodstream, or by release of undesirable particles of materials into the bloodstream that can cause embolization in the bloodstream.
With reference to FIGS. 1-10, the invention provides for an apparatus 40 including an elongated, flexible pusher member 42 for release and deployment of a therapeutic device 44 such as a vasoocclusive device, which may for example be a microcoil, only a portion of which is shown, within the vasculature of a patient, through a delivery catheter 46. The therapeutic device may alternatively be one or more electrodes, a stent, a coated coil, or the like, for example. The pusher member has a shaft 47 that provides a measure of thermal insulation to an interior lumen 48, as will be further explained below. The shaft of the pusher member typically has an outer diameter of approximately 0.015′′, and an inside diameter of approximately 0.007, and can be formed from polyethylene terephthalate (PET) tubing.
In a first embodiment illustrated in FIGS. 1, 2 and 5, the pusher member has a portion 50 with an entry port 52 in communication with the interior lumen, and a plug 54 at the distal end 56 of the pusher member, typically secured within the distal end of the pusher member by adhesive, such as a cyanoacrylate adhesive, for example.
A first connector member 58 is mounted to the elongated, flexible pusher member, and has a severable portion 60 disposed within the elongated, flexible pusher member that is capable of being broken by heating. The first connector member is typically formed from a molded thermoplastic material, such as high density polyethylene. In the first embodiment, the first connector member may be molded in the form of a rod 61 extending across and connected between opposing sides of the interior diameter of the interior lumen of the pusher member, as is shown in FIGS. 1 and 2.
In a second embodiment illustrated in FIGS. 3 and 6, in which the same elements from the first embodiment are shown with the same reference numbers, the first connector member may have the configuration of a post 62 connected at one end to the pusher member and having a free end with an enlarged portion 63 larger than the entry port, and having a severable portion 64 that is capable of being broken by heating, typically formed from a molded thermoplastic material, such as high density polyethylene, as is shown in FIG. 3.
In a third embodiment illustrated in FIGS. 4 and 7, in which the same elements from the first embodiment are shown with the same reference numbers, the first connector member may have the configuration of a ring 65 connected to the pusher member and having a severable portion 67, that is capable of being broken by heating, typically formed from a molded thermoplastic material, such as high density polyethylene, as is shown in FIG. 4, for example.
In each embodiment, the therapeutic device includes an elongated second connector member 66 connected to the therapeutic device, such as by being looped through an end coil 68 of a microcoil therapeutic device, for example. The elongated second connector member may alternatively be tied or bonded to the therapeutic device, such as by heat bonding, or by an adhesive such as a cyanoacrylate adhesive, for example. The elongated second connector member is typically looped around the first connector member when the first connector member is a rod or post, or through the first connector member, when the first connector member is a ring. The elongated second connector member may be a connector fiber, or a ribbon, that may be made of polyethylene, or another suitable fiber material, for example. In a presently preferred embodiment, the elongated second connector member is formed of polyethylene, and is typically about 0.015 to 0.030 inches in diameter, although the elongated second connector member can be as thin as about 0.0005 inches in diameter, and can be formed from a variety of thermoplastic materials with high tensile strength. The elongated second connector member may also optionally be formed of a suitable high tensile strength material, for example.
In the foregoing embodiments, a heat source such as a resistive heat source coil 70 is disposed in the interior lumen of the pusher member adjacent to the severable portion of the first connector member for heating the severable portion of the first connector member to cause the severable portion of the first connector member to break and release the elongated second connector member, to thereby detach and deploy the therapeutic device from the flexible pusher member when a desired placement of the therapeutic device within the vasculature is achieved. The heat source may be spaced apart from the distal end of the pusher member. The heat source is connected by electrical connectors 72 to a control unit 74 which supplies electrical current to the resistive heat source coil to cause the severable connector member to break and release the therapeutic device. Alternatively, the heat source may deliver heat to the severable connector member by other means, such as thermo-mechanical, electromagnetic or RF energy, for example. The lumen of the pusher member advantageously provides an insulative space and wall thickness to contain the heating of the severable connector member to avoid thermal damage to surrounding tissues, and to help contain pieces of the severable connector member that may be formed during heating of the severable connector member to deploy the therapeutic device. The therapeutic device is thus detachably connected to the first connector member by the elongated second connector member, for placement of the therapeutic device within the vasculature.
In a fourth embodiment illustrated in FIGS. 8-10, in which the same elements from the first embodiment are shown with the same reference numbers, the first connector member has the form of a ring 76 mounted to the elongated, flexible pusher member. In the fourth embodiment, the first connector member is preferably an induction ring providing a heat source disposed in the interior lumen of the pusher member, and having a narrow, thin edge portion or blade 78, that can be heated. The blade is positioned to be in contact with the elongated second connector member 66, such as a fiber or ribbon that will melt when heated sufficiently, as explained above. The second connector member is connected to the therapeutic device, so that when the blade of the induction ring is heated, such as by electrical current from electrical connectors 72 connected to a control unit 74, as explained above, the first connector member will sever the second connector member, to release the therapeutic device.
It will be apparent from the foregoing that while particular forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.

## Claims

1. An apparatus for release and deployment of a therapeutic device within the vasculature of a patient, comprising:
an elongated, flexible pusher member having an interior lumen;
a first connector member mounted to said elongated, flexible pusher member, said first connector member including an induction ring disposed in the interior lumen of the pusher member, said induction ring having an edge portion configured to be heated;
an elongated second connector member connected to a therapeutic device and detachably connected to the first connector member, said elongated second connector member thereby connecting the therapeutic device to the pusher member for placement of the therapeutic device within the vasculature, said second connector member having a severable portion configured to be broken by heating disposed within said elongated, flexible pusher member, said severable portion of said second connector member being positioned in contact with said edge portion of said induction ring for heating said severable portion of said second connector member to cause said severable portion of said second connector member to break and release the elongated second connector member for detaching and deploying the therapeutic device from the flexible pusher member when a desired placement of the therapeutic device within the vasculature is achieved.

2. The apparatus of claim 1, further comprising a control unit, and wherein said induction ring is connected by electrical connectors to the control unit which supplies electrical current to the induction ring.

3. The apparatus of claim 1, wherein said flexible pusher member comprises a heat insulating shaft.

4. The apparatus of claim 1, wherein said pusher member includes an entry port communicating with said interior lumen of said pusher member, and said induction ring is disposed in the interior lumen of the pusher member adjacent to said entry port.

5. The apparatus of claim 1, wherein said elongated second connector member is a connector fiber.

6. The apparatus of claim 1, wherein said elongated second connector member comprises a ribbon.

7. The apparatus of claim 1, wherein said flexible pusher member has a distal tip, and the induction ring is spaced apart from said distal tip of said flexible pusher member.

8. The apparatus of claim 1, wherein said therapeutic device is a vasoocclusive device.

9. The apparatus of claim 1, wherein said therapeutic device comprises a microcoil.