Patent Application
20180147078
The present disclosure relates generally to medical device assemblies. More specifically, the disclosure relates to an assembly and method(s) for delivering a multi-segment device, including but not limited to a stent, to a body vessel in order to treat a disease.
Various implantable medical devices can be deployed within the lumen of a body vessel using minimally-invasive transcatheter techniques. Such devices can include an expandable frame configured for implantation in the lumen of a body vessel, such as an artery, a vein, or another body cavity. Minimally invasive techniques and instruments for placement of intraluminal medical devices have been developed to treat and repair undesirable conditions by implantation of the medical devices within body vessels. Intraluminal medical devices can be introduced to a point of treatment within a body vessel using a delivery catheter device passed through the blood vessels communicating between a remote introductory location and the implantation site, and released from the delivery catheter device at the point of treatment within the body vessel. Intraluminal medical devices can be deployed in a vessel at a point of treatment, the delivery device withdrawn from the vessel, and the medical device retained within the vessel to provide sustained improvement in vascular function or to increase vessel patency. Implantable medical devices can desirably comprise features that secure the implantable device within the body vessel upon deployment.
In certain circumstances, including in the treatment of disease conditions which present clinical situations in which a vessel of a patient needs to be artificially supported to maintain an open passageway through which fluids, such as blood, can flow, a certain region of a blood vessel may benefit from being kept open while still allowing flexibility during treatment. For example, blood flow through an artery can be impeded due to a build-up of cholesterol on the interior wall of the vessel. Also, vessel walls can be weakened be a variety of conditions, such as aneurysms.
Intraluminal support frames, sometimes referred to as stents, can provide an artificial mechanism to support a body vessel. Stents are typically tubular-shaped members that are placed in the lumen of the vessel and, once deployed, exert a radially-outward directed force onto the vessel wall to provide the desired support. Stents are typically positioned at the point of treatment or target site by navigation through the vessel, and possibly other connected vessels, until the point of treatment is reached. This navigation may require the stent to be able to move axially through the vessel(s) prior to deployment, while still maintaining the ability to exert an outward force on the interior wall once deployed. Accordingly, stents typically have radially unexpanded and expanded configurations. In the unexpanded configuration, the stent has a relatively small diameter that allows it to move axially through the vessel. In the expanded configuration, the stent has a relatively large diameter that allows it to exert an outward force on the interior wall of the lumen, thereby providing the desired support to the vessel.
In the case in which extra flexibility is desired, a segmented medical device such as a segmented stent may be employed. A segmented medical device may be delivered as a single interconnected unit, with its several separable members detaching from one another at the time of implantation in order to provide both the support of the conventional stent due to the radial stiffness of each segment and the increased flexibility that arises from separation of the portions.
Although the separable, segmented device may have advantages, the delivery of such a device is not trivial. Because of the longitudinal sliding freedom of the segments of such devices, alignment of the portions can be compromised if the delivery apparatus is not designed to compensate for positional changes that occur under normal delivery circumstances.
As such, it has been a challenge to develop a delivery assembly that allows for reliable delivery of a segmented medical device in such a way that maintains substantially uniform spacing between the segments of the device.
The invention may include any of the following embodiments in various combinations and may also include any other aspect described below in the written description or in the attached drawings. This disclosure provides a medical device assembly and methods for delivery of a multi-segment medical device.
In one embodiment, a delivery assembly is provided. The assembly may include a balloon catheter. The balloon catheter may include a catheter body having a first end and extending distally to a second end, the catheter body including a lumen therein. The balloon catheter may also have an expandable balloon disposed circumferentially about the catheter body, the balloon having a proximal portion with a proximal end and a distal portion with a distal end, the proximal end being disposed distal the first end and the distal end being disposed proximal the second end of the catheter body. The assembly may have a retention member disposed at the distal portion of the balloon for allowing an expansion profile of the balloon. The assembly may have a medical implant having a tubular body comprising a plurality of detachable segments, the medical implant being movable between a collapsed configuration and an expanded configuration, the medical implant being disposed about the balloon.
In another embodiment, a delivery assembly is provided. The assembly may include a balloon catheter. The balloon catheter may include a catheter body having a first end and extending distally to a second end, the catheter body including a lumen therein. The balloon catheter may also have an expandable balloon disposed circumferentially about the catheter body, the balloon having a proximal portion with a proximal end and a distal portion with a distal end, the proximal end being disposed distal the first end and the distal end being disposed proximal the second end of the catheter body. The assembly may have a retention member disposed at the distal portion of the balloon for allowing an expansion profile of the balloon. The retention member may be conical and be made of a biocompatible elastomer. The assembly may have a medical implant having a tubular body comprising a plurality of detachable segments, the medical implant being movable between a collapsed configuration and an expanded configuration, the medical implant being disposed about the balloon. The implant may be a segmented stent.
In another embodiment, a method is described. The method may include introducing a delivery assembly to a site to be treated. The assembly may include a balloon catheter. The balloon catheter may include a catheter body having a first end and extending distally to a second end, the catheter body including a lumen therein. The balloon catheter may also have an expandable balloon disposed circumferentially about the catheter body, the balloon having a proximal portion with a proximal end and a distal portion with a distal end, the proximal end being disposed distal the first end and the distal end being disposed proximal the second end of the catheter body. The assembly may have a retention member disposed at the distal portion of the balloon for allowing an expansion profile of the balloon. The assembly may have a medical implant having a tubular body comprising a plurality of detachable segments, the medical implant being movable between a collapsed configuration and an expanded configuration, the medical implant being disposed about the balloon. The method may include expanding the proximal portion free of the retention member by introducing an inflation fluid through the inflation lumen and into the interior of the expandable balloon. The method may include continuing to add the inflation fluid such that the distal portion constrained by the retention member which expands radially after the retention member expands radially first. The method may include contracting the expandable balloon to deploy the medical implant to the target location.
Various additional features and embodiments will become apparent with the following description. The present disclosure may be better understood by referencing the accompanying figures.
The present disclosure will now be described more fully with reference to the accompanying figures, which show various embodiments. The accompanying figures are provided for general understanding of various embodiments and method steps. However, this disclosure may be embodied in many different forms. These figures should not be construed as limiting, and they are not necessarily to scale. The following definitions will be used in this application.
“About” or “substantially” mean that two given quantities (e.g. lengths, areas or volumes) are within 10%, preferably within 5%, more preferably within 1%. For example, a first quantity of length can be within 10% of a second length quantity.
“Adjacent” referred to herein is near, near to, or in close proximity with.
“Longitudinally” and derivatives thereof will be understood to mean along the longitudinal axis of the device or device assembly.
The terms “proximal” and “distal” and derivatives thereof will be understood in the frame of reference of a physician using the device. Thus, proximal refers to locations closer to the physician and distal refers to the locations farther away from the physician (e.g., deeper in the patient's vasculature).
The term “biocompatible” refers to a material that is substantially non-toxic in the in vivo environment of its intended use, and that is not substantially rejected by the patient's physiological system (i.e., is non-antigenic).
As used herein, the term “body vessel” means any body passage lumen that conducts fluid, including but not limited to blood vessels, esophageal, intestinal, biliary, urethral and ureteral passages.
The architecture of a segmented stent may allow for segments of the stent to remain coupled for structural stability during loading and during delivery to a target site, and to uncouple during radial expansion whereby the segments are at least one of longitudinally or circumferentially movable relative to one another after disengagement. Particularly, mating elements forming the interlocking joints described herein that couple adjacent segments in an interlocking relationship and which disengage during expansion of the implant may be provided. For example, stents with these interlocking joints have provided suitable resistance to various mechanical loading from the vessels, such as axial loads (such as compression and tensile, especially resistance to longitudinal stretching), bending loads (such as longitudinal bending), and torque loads. Torque loading and axial loading may occur especially during maneuvering and orienting the stent to the target site. Torque loading and axial loading may also occur during balloon inflation due to uneven expansion of the balloon 50, thereby causing a phenomenon known as “dog-boning,” as shown by region 62 of
Uneven expansion of the balloon 50, such as under conditions that give rise to dog-boning, can lead to deformation of the fully-expanded device.
Turning now to
In order to modulate or adjust the inflation profile of an expandable balloon of an assembly for delivery and implantation of a segmented device, a retention member 10 as shown in
The retention member 10 is preferably made of a resilient material, one that will resist expansion as the balloon inflates to a certain point, and then finally expands as the remainder of the balloon has filled with an inflation fluid. The retention member may be made of a biocompatible material, such as a biocompatible elastomer, including for example a rubber or a polymer. The retention member 10 may have a radial force resistance to being radially expanded equal to, or greater than, the medical implant crimped over the balloon, such that it expands last when the balloon is inflated.
In one embodiment, the retention member 10 may be a separate component formed independently from the remainder of the delivery assembly. The retention member 10 may then be attached to the assembly such as with an adhesive. In another embodiment, the retention member may be placed over the distal portion of the balloon and may remain in place due to its elasticity, or its tendency to produce an inward radial force. In certain embodiments, the balloon 50 may have a textured surface such that the retention member does not slide off of the balloon. Such a textured surface may include surface roughening or microbristles.
In another embodiment, the retention member may be unitary with the balloon. One example of a unitary retention member is, for example, a coating applied to the outer surface of the distal portion of a balloon. The coating could be applied by any conventional method, such as spray coating or dip coating, and may be made of the same material as the balloon or a different material. In another embodiment, the unitary retention member may be a thickened balloon wall, as will be described in accordance with the description of
As depicted in
A number of luminal configurations for the balloon catheter 22 are possible. One lumen design is shown in
In another embodiment, the lumen configuration of a catheter assembly in accordance with another embodiment of the present invention is illustrated. In this embodiment, inflation lumen 233 extends further into the interior of balloon 250, with a side port 235 providing fluid communication between the lumen of the inflation catheter and the interior of the balloon. The inflation lumen also includes a closed end 234 such that fluid can only be injected through the side port 235. In a related embodiment, the closed end 234 may be located distal the distal end of balloon 250.
The balloon 50 of a catheter assembly may be fluid-tight so as to avoid leaking of inflation fluid. Typically, the inner surfaces of the balloon 50 is sealably attached to the catheter shaft 23 to prevent leakage of fluid. Means of sealing the balloons may include, for example, heat sealing, using an adhesive to form the seal, forced convection heating, radio frequency heating, ultrasonic welding, and laser bonding. Shrink tubing can be used as a manufacturing aid to compress and fuse the balloon to the catheter shaft defining either of the wire guide lumen 43 and the inflation lumen 33. If the catheter shaft 23 has an outer coating, the balloon 50 can be bonded to the coating or directly to the catheter shaft.
Optionally, the delivery assembly can include radiopaque material to provide a means for locating the multiple-balloon catheter within a body vessel. For example, the catheter shaft 23 can include one or more marker bands annularly disposed around the outside of the catheter shaft within the balloon 50. If desired, radiopaque bands can be added to the catheter shaft. Radiopaque marker bands can be used by a clinician to fluoroscopically view and locate the distal portion of the multiple-balloon catheter at a point of treatment within a body vessel. The radiopaque material can comprise any suitable opacifying agent.
In some embodiments, the delivery assembly may not have an outer sheath covering the balloon 50 and the implant 60 crimped over the balloon. Such an arrangement may be advantageous as it reduces the profile of the delivery assembly. In other embodiments, an outer sheath may surround the delivery assembly, which may be as depicted in
In some embodiments, the medical implant to be delivered may be a segmented stent.
The stent 410 includes a plurality of stent segments coupled together by a plurality of interlocking joints 430. In one example, the axial stent segments comprise one or more ring structures 412 disposed axially relative to one another along a longitudinal axis L. The stent 410 is defined as a tubular body defining a lumen disposed about the longitudinal axis L between a first stent end (not shown) and a second stent end 420. The tubular body includes an exterior surface to contact the body vessel wall and an opposite, interior surface facing the lumen. Adjacent ring structures 412 (for example, a first ring structure 412A and a second ring structure 412B) may be coupled to one another by the interlocking joints 430. Also shown is that adjacent ring structures 412 may be interconnected by a plurality of tie bars.
The ring structure 412 has a substantially circular ring shape comprising an undulating arrangement of interconnected unit stent struts 418. The undulating arrangement may be also defined also as a serpentine or zigzag pattern. The stent struts 418 may be connected to one another at opposite joints to define a first series of apices disposed axially opposite and circumferentially offset to a second series of apices. The stent segments of the stent 410 may be comprised of ring structures 412, axial stent members, or combination of the two. Depending on the location of the axial stent member or ring structure 412, the tie bars and/or interlocking joints 430 may be omitted from the corresponding inner apices and/or outer apices. For example, when the axial stent member or ring structure 412 is disposed along the outermost extreme axial ends of the stent 410, the outer apices may not include any tie bar or interlocking joint. Further, depending on the environment and length of the point of treatment, a single ring structure 412 may be used along the end of the stent 410, rather than the axial stent member comprising of two or more ring structures 412.
First step 100 is illustrated in
In a second step 101, inflation fluid has begun to flow into the interior of the balloon 50 to create a partially-inflated balloon having partially expanded or inflated proximal portion 56. Inflation at the proximal portion 51 is possible because proximal portion 51 is free from a constraining member, whereas distal portion 52 is held radially contracted by retention member 10. Similarly, the proximal-most portion of radially expandable device 60 has begun to radially expand because of the radial expansion of proximal portion 51 of the balloon.
In a third step 102, illustrated in
It will be appreciated that any balloon, assembly, and catheter design as disclosed herein may be employed to affect the method of
It should be understood that the foregoing relates to exemplary embodiments of the disclosure and that modifications may be made without departing from the spirit and scope of the disclosure as set forth in the following claims. While the disclosure has been described with respect to certain embodiments it will be appreciated that modifications and changes may be made by those skilled in the art without departing from the spirit of the disclosure.
| Number | Date | Country | |
|---|---|---|---|
| 62427876 | Nov 2016 | US |
