Patent Application
20230181190
The present invention relates to a medical device for placing an implantable medical device at a predetermined site within a vessel of the human body, and more particularly, relates to a catheter-based deployment system for delivering an embolic device.
For many years, flexible catheters have been used to place various devices within the vessels of the human body. Such devices include dilation balloons, radiopaque fluids, liquid medications, and various types of occlusion devices such as balloons and embolic coils. Coils which are placed in vessels may take the form of helically wound coils, or alternatively, may take the form of randomly wound coils, coils wound within coils or other such coil configurations. Often, several coils are placed at a given location to occlude the flow of blood through the vessel, or aneurysm, by promoting thrombus formation at the particular site.
In the past, embolic coils have been placed within the distal end of a catheter. When the distal end of the catheter is properly positioned, the coil may then be pushed out of the end of the catheter with a pusher member to release the coil at the desired location. This procedure for placement of an 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 placed at the desired location.
Other coil deployment systems incorporate interlocking mechanisms on the coil. In such systems, the interlocking end on the embolic coil couples with a similar interlocking mechanism on a pusher assembly. In one example system, a control wire extends through the locking mechanism and secures the coil to the pusher assembly. When the embolic coil is pushed out of the end of the catheter for placement, the control wire is retracted, and the coil disengages from the pusher assembly. Such a deployment system is disclosed in U.S. Pat. No. 5,925,059, entitled “Detachable Embolic Coil Assembly.”
Another system includes a catheter with an expandable reaction chamber within the catheter lumen and a gripper at the distal end of the catheter that is lassoed around a headpiece of a coil. The reaction chamber has multiple chambers separated by a heat-dissolvable membrane. When the membrane is dissolve, the components from the chambers react and expand, causing the expandable gripper to deploy the coil. Such a coil positioning system is disclosed in U.S. Pat. No. 8,449,591, entitled “Chemically based vascular occlusion device deployment.”
Yet another coil deployment system is that of a catheter having a locking member with a Y-shaped hook holding a loop of the coil at the distal end of the catheter. When the Y-shaped hook is deployed out of the catheter sleeve, the hook opens and thus releases the loop and deploys the coil. Such coil deployment system is disclosed in U.S. Pat. No. 8,974,488, entitled “Delivery assembly for occlusion device using mechanical interlocking coupling mechanism.”
Still another system for placing an embolic coil within a vessel is that of a plunger device with an enlarged head within a catheter which can be pulled against tapered internal surfaces of the catheter, causing the gripper arms of the catheter to expand and release the coil at the end of the gripper arms. Such a procedure is disclosed in U.S. Pat. No. 10,034,670, entitled “Medical implant detachment mechanism and introducer assembly.”
Yet another coil deployment system incorporates a catheter having a pushrod with a flexible socket at the distal end holding a ball-tip of a coil. When the pushrod is advanced distally such that the flexible socket is outside of the catheter, the socket deforms to allow the ball-tip to be released and thereby deploy the coil. Such a coil positioning system is disclosed in U.S. Pat. No. 10,888,331, entitled “Active release of embolic coils.”
However, for at least some of the above systems, it can be difficult to positively and smoothly releasing the embolic coil. Applicants recognize that there is a need to securely hold the pull-wire in place until the embolic coil is ready to be deployed to avoid premature detachment, however, if the securement force is too high, the embolic coil may not be easily released. Thus, there is a need for alternative systems which accomplish these goals.
Thus, an example of an implantable medical device detachment system to place an implantable medical device, such as an embolic coil or a balloon, at a predetermined site within a vessel can include a generally hollow distal tube and an engagement system. The distal tube can include a proximal end, a distal end, an inner lumen with a first diameter therethrough, and a narrowed portion with a second diameter less than the first diameter. The narrowed portion can be positioned on at least a portion of the distal end of the distal tube. The engagement system can be slidably disposed within the inner lumen. The engagement system can include a detachment feature and a locking member. The detachment feature can be connected to the implantable medical device. The locking member can include a proximal portion extending through the proximal end of the distal tube. Further, the locking member can include a distal end that can interface with the narrowed portion of the distal tube and engage the detachment feature. The locking member can also be configured to deploy the implantable medical device engaged at the distal end of the distal tube. Therefore, when the locking member is engaged with the detachment feature and the detachment feature is connected to the implantable medical device, the locking member is in an engaged position, retaining the implantable medical device proximal to the tip of the catheter. When the proximal portion of the locking member is pulled proximally, the locking member is displaced from the detachment feature, thereby releasing the implantable medical device. The implantable medical device can be an embolic coil.
The narrowed portion of the distal tube can include one or more protrusions. In some examples, the one or more protrusions can approximately circumscribe the inner lumen.
The locking member of the engagement system can further include two or more appendages. The appendages can be configured to move between an engaged configuration and an open configuration, and further define a cavity between the two or more appendages. The cavity can be configured to fit at least a portion of the detachment feature when the locking member is in the engaged configuration.
The locking member can be configured to deploy the detachment feature from the cavity when the two or more appendages are in the open configuration. In some examples, this is accomplished because the locking member includes a flexible material. The two or more appendages are in the engaged configuration when the locking member interfaces with the narrowed portion of the distal tube, and in the open configuration when the locking member is displaced from the narrowed portion of the distal tube. In some examples, when the locking member is moved proximally in a way that the distal end of the locking member is displaced from the narrowed portion of the distal tube, the locking member is configured to deploy the implantable medical device engaged at the distal end of the distal tube.
The locking member can additionally include a knob at a distal end of each respective appendage. The cavity of the locking member can include a cavity width. Further, the knobs on each of the one or more appendages can define a knob width. In some examples, the cavity width can be larger than the knob width when in the engaged configuration. Further, the detachment feature can include a detachment feature width. The detachment feature width can be sized between the cavity width and the knob width in the engaged configuration. When in the open configuration, the locking member can have an open locking member width formed by the knobs of each of the one or more appendages. The open locking member width can be larger than the knob width in the engaged configuration. The detachment feature can have a detachment feature width that is sized less than the open locking member width when in the open configuration.
The detachment system can further include a distal stopped positioned at the distal end of the distal tube.
Another example of detachment system similar to the above can include the detachment feature engaging with the locking member, where the locking member can be configured to be in the engaged configuration when interfacing with the narrowed portion of the distal tube and in the open configuration when displaced from the narrowed portion of the distal tube, thereby deploying the implantable medical device connected to the detachment feature. Additionally, the locking member can be configured to be pulled proximally through the distal tube such that the locking member is displaced from the narrowed portion. In some examples, this is accomplished because the locking member includes a flexible material, such as nitinol.
A method of manufacturing an example detachment system as described above can include narrowed at least a portion of a distal tube and positioning an engagement system within the narrowed portion of the distal tube. The engagement system can include a detachment feature connected to an implantable medical device and a locking member. The locking member can include a proximal portion extending through the distal tube, and a distal end having two or more flexible appendages defining a cavity configured to fit at least a portion of the detachment feature. The distal end can be configured to interface with the narrowed portion of the distal tube, engage the detachment feature, and deploy the implantable medical device engaged at a distal end of the distal tube.
Narrowing the distal tube can include crimping the distal tube in such a way that decreases a diameter of an inner lumen of the distal tube. Alternatively, or in addition thereto, narrowing the distal tube can include positioning one or more protrusions within the distal tube in such a way that decreases a diameter of an inner lumen of the distal tube.
The method can additionally include securing the detachment feature within the cavity formed from the two or more flexible appendages of the locking member in an engaged configuration. Further, the method can also include releasing the detachment feature from the cavity formed from the two or more flexible appendages of the locking member in an open configuration.
In some examples, the method includes sliding the locking member proximally within the distal tube such that upon displacement of the locking member from the narrowed portion, the locking member transitions from the engaged configuration to the open configuration.
This invention is described with particularity in the appended claims. The above and further aspects of this invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
The drawing figures depict one or more implementations in accord with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements.
The following detailed description should be read with reference to the drawings, in which like elements in different drawings are identically numbered. The drawings, which are not necessarily to scale, depict selected examples and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several examples, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.
As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, “about” or “approximately” may refer to the range of values±10% of the recited value, e.g. “about 90%” may refer to the range of values from 81% to 99%. In addition, as used herein, the terms “patient,” “host,” “user,” and “subject” refer to any human or animal subject and are not intended to limit the systems or methods to human use, although use of the subject invention in a human patient represents a preferred embodiment. As well, the term “proximal” indicates a location closer to the operator whereas “distal” indicates a location further away to the operator or physician.
The figures illustrate a generally hollow or tubular structure according to the present invention. When used herein, the terms “tubular” and “tube” are to be construed broadly and are not limited to a structure that is a right cylinder or strictly circumferential in cross-section or of a uniform cross-section throughout its length. For example, the tubular structure or system is generally illustrated as a substantially right cylindrical structure. However, the tubular system may have a tapered or curved outer surface without departing from the scope of the present invention.
In a mechanical detachment system, a pull-wire holds the implantable medical device to the system and when the pull-wire with an engagement system described herein is translated in the proximal direction, the engagement system detaches the implant to the target location. It is crucial to hold the wire, engagement system, and implant in place until it is ready to be translated. Inability to hold the wire in place may cause a premature detachment of the implant. A detachment system with a reliably secured locking member and readily slidable detachment mechanism may avoid premature detachment as well as an overly high securement force required for deployment. The pull-wire may have a solid or hollow core along a majority of its length.
An example of a detachment system 10 of the present invention, as illustrated in
The detachment system 10 may include a medical device 12 which, in an example, takes the form of a helically wound embolic coil disposed at the distal end 304 of the distal tube 300. While the medical device 12 as is illustrated is shown as a helically wound coil, other types of embolic devices, such as filaments, braids, foams, expandable meshes and stents, could be delivered using the present deployment system and various other coil configurations could be delivered using this system. A coil may be relatively stiff and made of stainless steel or it may be soft and made of platinum. Extremely soft coils may be made with either a spiral shape or a more complex shape to promote deployment at the desired delivery location and to promote a higher packing density. The diameter of a coil is selected in consideration of the size of the aneurismal sac. Generally, the medical device 12 may be very small and thin, ranging in a variety of shapes and sizes. The medical device 12 may come in various random loop designs to conform to the aneurysm shape, and various deployments of the coil device may be used. A coil can vary in softness and in stiffness. The coil size can range from about twice the width of a human hair to less than one hair's width. The number of loops in a coil may vary. Platinum coils may be between 0.010 inches and 0.025 inches in diameter. A coil may vary from 1 to 60 centimeters in length, with some as long as 100 centimeters.
As shown in
The distal tube 300 can be made of a biocompatible material, such as stainless steel. The distal tube 300 can typically have a diameter of between about 0.010 inch and about 0.018 inch, a preferred tube having a diameter of approximately 0.0145 inch. These examples of tube size are suitable for delivering and deploying embolic coils to target locations, typically aneurysms, within the neurovasculature. Differently sized tubes 300 comprised of other materials may be useful for different applications and are within the scope of the present invention.
Although not depicted, in some examples, the distal tube 300 can be delivered to a subject using an outer catheter. The catheter size is selected in consideration of the size, shape, and directionality of the aneurysm or the body lumens the catheter must pass through to get to the treatment site. The catheter 2 may have a total usable length anywhere from 80 centimeters to 165 centimeters and a distal length of anywhere between 5 centimeters to 42 centimeters. The catheter 2 may have an inner diameter ID of anywhere between 0.015 and 0.025 inches. The outer diameter ID may also range in size and may narrowed at either its proximal end or distal end. The outer diameter may be 2.7 French or less.
The engagement system 400 can be slidably disposed within the inner lumen 308 of the distal tube 300. The engagement system 400 can include a detachment feature 130 connected to the implantable medical device and a locking member 140. The detachment feature 130 can be configured to fit inside the inner lumen 308 of the distal tube 300 and interface with the locking member 140. The detachment feature 130 can have a proximal coupling portion that is separate from the implantable medical device 12 such that the locking member 140 interfaces the proximal coupling portion of the detachment feature 130 within the inner lumen 108 of the distal tube 300 while the implantable medical device 12 remains distal and external of the distal tube 300.
As depicted in
The distal end 144 of the locking member 140, as shown in
As depicted in
As is apparent, there are numerous modifications of the preferred example described above which will be readily apparent to one skilled in the art, such as many variations and modifications of the embolic device including numerous coil winding configurations, or alternatively other types of embolic devices. Also, there are many possible variations in the materials and configurations of the release mechanism. These modifications would be apparent to those having ordinary skill in the art to which this invention relates and are intended to be within the scope of the claims which follow.
