HANDLE ASSEMBLIES FOR STENT GRAFT DELIVERY SYSTEMS AND ASSOCIATED SYSTEMS AND METHODS
Handle assemblies for stent graft delivery systems and associated methods are disclosed herein. In several embodiments, a handle assembly for a stent graft delivery system includes a movable pushing component configured to deliver a distal portion of the stent graft to an arterial target site. The assembly further includes a moveable pulling component configured to interface with the pushing component and provide a compression force to the distal portion of the stent graft. The stent graft comprises a helix angle and the pulling component is configured to move relative to the pushing component at a ratio corresponding to the helix angle.
The present application claims priority to each of the following U.S. Provisional Patent Applications:
(A) U.S. Provisional Patent Application No. 61/681,907, filed on Aug. 10, 2012, and entitled “Handle Assemblies for Stent Graft Delivery Systems and Associated Systems and Methods;” and
(B) U.S. Provisional Patent Application No. 61/799,591, filed Mar. 15, 2013, and entitled “Handle Assemblies for Stent Graft Delivery Systems and Associated Systems and Methods.”
Each of the foregoing applications is incorporated herein by reference in its entirety.
TECHNICAL FIELDThe present technology relates to treatment of abdominal aortic aneurysms. More particularly, the present technology relates to handle assemblies for stent graft delivery systems and associated systems and methods.
BACKGROUNDAn aneurysm is a dilation of a blood vessel of at least 1.5 times above its normal diameter. The dilated vessel forms a bulge known as an aneurysmal sac that can weaken vessel walls and eventually rupture. Aneurysms are most common in the arteries at the base of the brain (i.e., the Circle of Willis) and in the largest artery in the human body, the aorta. The abdominal aorta, spanning from the diaphragm to the aortoiliac bifurcation, is the most common site for aortic aneurysms. Such abdominal aortic aneurysms (AAAs) typically occur between the renal and iliac arteries, and are presently one of the leading causes of death in the United States.
The two primary treatments for AAAs are open surgical repair and endovascular aneurysm repair (EVAR). Surgical repair typically includes opening the dilated portion of the aorta, inserting a synthetic tube, and closing the aneurysmal sac around the tube. Such AAA surgical repairs are highly invasive, and are therefore associated with significant levels of morbidity and operative mortality. In addition, surgical repair is not a viable option for many patients due to their physical conditions.
Minimally invasive endovascular aneurysm repair (EVAR) treatments that implant stent grafts across aneurysmal regions of the aorta have been developed as an alternative or improvement to open surgery. EVAR typically includes inserting a delivery catheter into the femoral artery, guiding the catheter to the site of the aneurysm via X-ray visualization, and delivering a synthetic stent graft to the AAA via the catheter. The stent graft reinforces the weakened section of the aorta to prevent rupture of the aneurysm, and directs the flow of blood through the stent graft away from the aneurismal region. Accordingly, the stent graft causes blood flow to bypass the aneurysm and allows the aneurysm to shrink over time.
In some systems, braided stent grafts are delivered in an elongated state. Upon delivery from a delivery catheter, the stent graft will elastically shorten into its free state. In other words, the effective length of the stent graft changes as its diameter is forced smaller or larger. For example, a stent graft having a shallower, denser helix angle will result in a longer constrained length. Once the stent graft is removed from a constraining catheter, it can elastically return to its natural, free length.
Delivering a stent graft to an artery requires precise alignment of the distal edge of the stent graft relative to a target location in the destination artery. For example, a misplaced stent graft can block flow to a branching artery. Some stent graft delivery systems utilize one or more markers (e.g., radiopaque markers) to establish the alignment of the stent graft distal edge relative to the artery wall. However, the location of the radiopaque markers on the stent graft can move relative to an initial marker position because of the change in the stent graft's effective length upon delivery, as described above. Accordingly, the stent graft will be deployed, but a distal edge of the stent graft may miss the target point in the artery. Therefore, there exists a need for improved and reliable placement of stent grafts.
The present technology is directed toward handle assemblies for stent graft delivery systems and associated systems and methods. In several embodiments, for example, a handle assembly for a stent graft delivery system can include a movable pushing component configured to deliver a distal portion of the stent graft to an arterial target site, and a movable pulling component configured to interface with the pushing component and provide a compression force to the distal portion of the stent graft. The stent graft can include, for example, a helix angle and the pulling component may be configured to move relative to the pushing component at a ratio corresponding to the helix angle.
Certain specific details are set forth in the following description and in
In this application, the terms “distal” and “proximal” can reference a relative position of the portions of an implantable stent graft device and/or a delivery device with reference to an operator. Proximal refers to a position closer to the operator of the device, and distal refers to a position that is more distant from the operator of the device. Also, for purposes of this disclosure, the term “helix angle” refers to an angle between any helix and a longitudinal axis of the stent graft.
A handle assembly 110 at a proximal portion of the delivery system 100 can be used to controllably release the stent graft from the outer sheath 150. In several embodiments of the present technology, the handle assembly 110 is configured deliver the stent graft in a manner as to keep the initial marker positions relative to the arterial wall from changing upon final stent graft deployment. In several embodiments the stent graft can be delivered with a “push/pull” stroke of the handle assembly 110 during delivery. The proximal portion of the stent graft can be pushed out of the sheath 150 in a traditional manner, while simultaneously the distal end of the stent graft can be axially compressed. The net effect is that during the deployment of the stent graft, the pushing and pulling results in a net zero migration of the marker. There is a natural ratio between the amount of pull for every length of push. In various embodiments, different stent graft diameters, helix angles, and geometry may require different optimum push to pull ratios. In some embodiments, the handle assembly 110 can comprise a “double helix”, that provides for both unsheathing and resheathing a stent without having to swap handles.
As will be described in further detail below, the handle assembly 110 can incorporate various mechanisms to achieve the desired push to pull ratio. In several of the embodiments described below, these mechanisms maintain the axial position of the deployed portion of the stent graft by synchronizing the action of pulling back the sheath 150 simultaneous with pushing the stent graft forward. When the ratio of these actions are matched to or correspond to the helix angle of the braided stent graft, the deployed stent graft will be stationary relative to a destination artery target location.
The stent can be incrementally deployed/unsheathed with a “jackhammer” type motion. The incremental deployment provides the stent with an opportunity to gradually reshape. For example, the stent can comprise shape-memory material such as Nitinol. The stent can be straightened within the sheath for delivery, and then incrementally reshaped to its natural state upon deployment. The incremental reshaping allows a practitioner to partially deploy the stent, reposition the stent as necessary to best interface with the vasculature, and then fully deploy, allowing the stent to fully resume its natural state shape. A further example of this incremental deployment “jackhammer” feature is illustrated as a slider mechanism shown in
The handle assembly 1010 further includes a seal (e.g., a silicon disc) 1036 configured to block blood or other fluid from traveling into the handle assembly 1010. The seal 1036 accordingly can prevent contamination and/or malfunction of the handle assembly 1010. In further embodiments, the seal 1036 can comprise other biocompatible materials.
In some embodiments, the handle assemblies 1710 can deploy the stent graft using a lead screw to facilitate placement, and can accurately and smoothly deliver the stent graft without requiring an outer sheath or external screws on the handle assemblies 1710. In additional embodiments, the handle assemblies 1710 can, further include a tip-release screw configured to control the release of the stent tip. The handle assemblies 1710 may also include audio feedback during unsheathing (e.g., “clicks” upon rotation of one or more of the handle assembly rotation cuffs 1740 or other suitable audio feedback mechanisms). The handle assemblies 1710 can further include a disengageable anti-rotation feature for re-docking or ease of sheath withdrawal. Contrast can be delivered via a system internal to the handle assemblies 1710 or via an introducer sheath. In still further embodiments, contrast can be delivered via other systems or mechanisms. In some embodiments, the mechanics of the handle assemblies 1710 make them easy to disassemble, e.g., in 15 seconds or less.
In further aspects of the technology, stent graft delivery systems can be configured to continuously or simultaneously deploy and expand a stent graft at a treatment site, as opposed to the incremental deployment provided by the “jackhammer” type movement discussed above. In this embodiment, the exposure of the stent graft from the sheath is synchronized with a forced diametric expansion of the stent graft (i.e., the stent graft is expanded as it is exposed). As discussed in further detail below, in some embodiments the simultaneous deployment and expansion of the stent graft is expected to enhance a clinical operator's ease of use.
The handle assembly 1810 can include a housing 1812, two lead screws (identified individually as a first lead screw 1850a and a second lead screw 1850b, and referred to collectively as lead screws 1850) within the housing 1812. The first and second lead screws 1850a and 1850b can be configured to travel in opposite directions at a selected fixed ratio (e.g., a pre-selected fixed ratio) that reduces (e.g., minimizes) movement of the stent at a target site during unsheathing to compensate for the stent transforming from a constrained state to its original expanded state. As shown in
Referring back to
Clinical evidence has shown that a payout ratio of about 1.5:1 results in a fully appositioned device with clinically and therapeutically appropriate length and diameter. Payout ratios ranging from about 1:1 to about 2:1 have also been shown to provide acceptable stent deployment. In other embodiments, the payout ratio may be higher or lower depending upon various clinical and/or anatomical considerations. A desired payout ratio can be achieved by coursing the pitch frequency of the first engagement section relative to the pitch frequency of the second engagement section at a degree proportional with the desired payout ratio.
In addition, in further aspects of the technology, the handle assembly 1810 can include features that reduce the likelihood (e.g., prevent) unintentional or undesired rotation of the internal screw, which may occur when the rotating handle 2 of the handle assembly 1810 is turned by the operator. For example, one or both of the travel lead screws 1850 can include a slot or recess 1856 that travels along a spine in the forward handle 1 to avoid rotation of the travel lead screws 1850 as the rotating handle 2 is turned by the operator.
In operation, the handle assembly 1810 described with reference to
In some embodiments, a handle assembly configured in accordance with the present technology may include a communicating system to the paired device (e.g., via wire, RF link, magnetic link, etc.) to help ensure that speed and/or rate of change are uniform during initial through final treatment of the device function. This feature may be configured to be engaged/disengaged based upon the physician's/user's preference. One feature of this arrangement is to provide harmonization relating to the delivery of the intended implant during the procedure with more than one physician/user interfacing with the device(s).
ADDITIONAL EXAMPLES1. A handle assembly for a stent graft delivery system, the handle assembly comprising:
-
- a movable pushing component configured to deliver a distal portion of the stent graft to an arterial target site; and
- a moveable pulling component configured to interface with the pushing component and provide a compression force to the distal portion of the stent graft, wherein
- the stent graft comprises a helix angle, and
- the pulling component is configured to move relative to the pushing component at a ratio corresponding to the helix angle.
2. The handle assembly of example 1 wherein the pushing component comprises a first rack and pinion and the pulling component comprises a second rack and pinion configured to interface with the first rack and pinion.
3. The handle assembly of example 1 wherein the pushing component comprises a first lead screw coupled to a rotatable shaft and having a first thread pitch, and wherein the pulling component comprises a second lead screw coupled to the shaft and having a second thread pitch different from the first thread pitch.
4. The handle assembly of example 1, further comprising a lumen extending axially through the handle assembly and configured to carry contrast or other fluid.
5. A reverse deployment handle assembly for a stent graft delivery system, the handle assembly comprising:
-
- a movable delivery component configured to deliver a distal portion of the stent graft to an arterial target site, wherein the delivery component employs synchronized push and compression forces on the stent graft; and
- a rotation cuff on an exterior portion of the handle assembly, wherein the rotation cuff is interfaced with the delivery component and configured to activate the synchronized push and compressions forces.
6. The handle assembly of claim 5 wherein the rotation cuff is rotatably movable into one or more lockable positions configured to control incremental placement of the stent graft.
7. The handle assembly of claim 6 wherein the rotation cuff is configured to provide audio feedback upon placement into the lockable positions.
8. The handle assembly of claim 5, further comprising a lead screw coupled to the movable delivery component and configured to facilitate placement of the stent graft.
9. The handle assembly of claim 5, further comprising a lumen extending axially through the handle assembly and configured to carry contrast or other fluid.
10. A handle assembly for a stent graft delivery system, the handle assembly comprising:
-
- a threaded unsheathing screw;
- a threaded position compensating screw interfaced with the unsheathing screw; and
- a ratchet system configured to torque the unsheathing screw and the position compensating screw.
11. The handle assembly of claim 10 wherein the unsheathing screw comprises threads of a first pitch and the position compensating screw comprises threads of a second pitch, and wherein the second pitch is different from and opposing the first pitch.
12. The handle assembly of claim 10 wherein the handle assembly comprises ergonomic contours.
13. A stent graft delivery system, comprising:
-
- a handle for housing, advancing ,and unsheathing a stent graft, wherein the handle comprises an internal lead screw engaged with a first travel lead screw and a second travel lead screw,
- wherein the first travel lead screw is mechanically coupled to a sheath covering the stent graft, and wherein the second travel lead screw is mechanically coupled to the stent graft via a dilator,
- wherein the first travel lead screw and second travel lead screw have opposing pitch angles such that rotation of the internal lead screw causes longitudinal translation of the sheath and stent graft in opposing directions, and
- wherein the first travel lead screw and second travel lead screw have pitch frequencies that enable opposing longitudinal translation of the sheath and stent graft at a predetermined payout ratio.
14. A handle assembly for housing, advancing, and unsheathing a stent graft, the housing assembly comprising:
-
- a first travel lead screw configured to be mechanically coupled to a sheath covering the stent graft;
- a second travel lead screw configured to be mechanically coupled to the stent graft via a dilator; and
- an internal lead screw engaged with the first and second travel lead screws,
- wherein the first and second travel lead screws have opposing pitch angles such that rotation of the internal lead screw causes longitudinal translation of the sheath and stent graft in opposing directions, and
- wherein the first and second travel lead screws have pitch frequencies that enable opposing longitudinal translation of the sheath and stent graft at a predetermined payout ratio.
The handle assemblies shown and described herein offer several advantages over previous devices. For example, the handle assemblies provide for straightforward delivery of a stent graft to an artery while maintaining initial stent graft marker positions relative to a destination arterial wall. Embodiments employing opposing screws provide a user with the ability to deliver a stent graft at a high force with relatively little mechanical effort. This allows a user to exercise improved control over the delivery process. Further, the mechanisms disclosed herein provide effective push/pull motion while minimizing the number of parts, assembly time, and cost. The push/pull components allow the handle assemblies to maintain a low profile and minimize the overall bulk of the delivery device.
From the foregoing, it will be appreciated that specific embodiments of the technology have been described herein for purposes of illustration, but that various modifications may be made without deviating from the disclosure. Certain aspects of the new technology described in the context of particular embodiments may be combined or eliminated in other embodiments. Additionally, while advantages associated with certain embodiments of the new technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein.
Claims
1-14. (canceled)
15. A stent delivery system for deploying a stent, comprising:
- a handle for advancing and unsheathing a stent, wherein the handle comprises a dual-threaded internal lead screw configured to engage with a first lead screw and a second lead screw,
- wherein the first lead screw is coupled to a tubular enclosure covering the stent and the second lead screw is selectively coupleable to the stent via a dilator,
- wherein the first lead screw and second lead screw are of opposing handedness such that rotation of the internal lead screw causes longitudinal translation of the tubular enclosure and stent in opposite directions, and
- wherein the first lead screw and second lead screw have respective pitches that enable synchronized, opposing longitudinal translation of the tubular enclosure and stent at a predetermined payout ratio to deploy the stent.
16. The stent delivery system of claim 15 wherein the predetermined payout ratio is equal to a helix angle of the stent.
17. The stent delivery system of claim 15 wherein the predetermined payout ratio is configured to reduce the movement of the stent during unsheathing of the stent.
18. The stent delivery system of claim 17 wherein the predetermined payout ratio of first lead screw to second lead screw is between about 1:1 and 2:1.
19. The stent delivery system of claim 18 wherein the predetermined payout ratio of first lead screw to second lead screw is about 1.5:1.
20. The stent delivery system of claim 15 wherein the handle further comprises a slider mechanism configured to provide incremental stent deployment and reshaping.
21. The stent delivery system of claim 15 wherein the handle further comprises a tip-release slider.
22. The stent delivery system of claim 15 wherein the handle further comprises a cuff mechanism configured to provide incremental stent deployment.
23. The stent delivery system of claim 15 wherein the handle defines one or more lockable positions configured to control incremental stent deployment.
24. The stent delivery system of claim 23 wherein the handle further comprises audio feedback upon placement of the cuff mechanism into the one or more lockable positions.
25. The stent delivery system of claim 15 further comprising a lumen extending axially through the handle and configured to carry contrast or other fluid.
26. The stent delivery system of claim 15 further comprising a seal configured to block fluid from traveling into the handle.
27. The stent delivery system of claim 15 wherein the second lead screw is configured to be in mechanical communication with the stent via a dilator.
28. The stent delivery system of claim 27 wherein, upon rotation of the housing around a longitudinal axis, the first lead screw pulls the tubular enclosure in a proximal direction and the second lead screw pushes a proximal end of the stent in a distal direction to provide simultaneous advancement of the stent and retraction of the tubular enclosure.
29. The stent delivery system of claim 15 wherein the first and second lead screws have semi-circular cross-sections.
30. The stent delivery system of claim 15 wherein the handle comprises at least one keyway spline that engages an axial groove in the first lead screw or second lead screw.
31. The stent delivery system of claim 30 wherein the handle assembly comprises ergonomic contours.
32. A handle assembly for a stent graft delivery system, the handle assembly comprising:
- a movable pushing component configured to deliver a distal portion of the stent graft to an arterial target site; and
- a moveable pulling component configured to interface with the pushing component and provide a compression force to the distal portion of the stent graft,
- wherein the stent graft comprises a helix angle, and
- the pulling component is configured to move relative to the pushing component at a ratio corresponding to the helix angle.
33. The handle assembly of claim 32 wherein:
- the pushing component comprises a first lead screw coupled to a rotatable shaft and having a first thread pitch; and
- the pulling component comprises a second lead screw coupled to the shaft and having a second thread pitch different from the first thread pitch.
34. The handle assembly of claim 32 further comprising a lumen extending axially through the handle assembly and configured to carry contrast or other fluid.
35. A handle assembly for housing, advancing, and unsheathing a stent graft, the housing assembly comprising:
- a first travel lead screw configured to be mechanically coupled to a sheath covering the stent graft;
- a second travel lead screw configured to be mechanically coupled to the stent graft via a dilator; and
- an internal lead screw engaged with the first and second travel lead screws,
- wherein the first and second travel lead screws have opposing pitch angles such that rotation of the internal lead screw causes longitudinal translation of the sheath and stent graft in opposing directions, and
- wherein the first and second travel lead screws have pitch frequencies that enable opposing longitudinal translation of the sheath and stent graft at a predetermined payout ratio.
Type: Application
Filed: Aug 9, 2013
Publication Date: Feb 20, 2014
Inventors: Andrew H. Cragg (Edina, MN), John Logan (Plymouth, MN), George Tsai (Mission Viejo, CA), Nelson Quintana (Temecula, CA), Mahmood Dehdashtian (Costa Mesa, CA)
Application Number: 13/963,912
International Classification: A61F 2/966 (20060101);