WO2016025860A1

WO2016025860A1 - Medical device with gear train

Info

Publication number: WO2016025860A1
Application number: PCT/US2015/045321
Authority: WO
Inventors: Taylor HEANUE; William E. Clem; Darius D. Eghbal; Ryan WHITAKER
Original assignee: Flexible Stenting Solutions, Inc.
Priority date: 2014-08-14
Filing date: 2015-08-14
Publication date: 2016-02-18
Also published as: WO2016025820A1; WO2016025896A1; WO2016025888A1

Abstract

A stent delivery system having the ability to recapture or reconstrain a partially deployed self-expanding stent may have a variable gap between a stent and a respective proximal or distal stop, which respective stop limits the axial travel of a stent lock interfacing with the stent, and supports it during. Including in the housing of a handle assembly a gear train that converts a known angle of rotation of an input knob about a first axis into a variable distance of translation of an output along a second axis perpendicular to the first enables the user to close the gap reliably. The mechanism described herein requires a known, repeatable step to close a gap that can vary in length that makes the variation in the gap "invisible" to the user.

Description

MEDICAL DEVICE WITH GEAR TRAIN

[01]. RELATED APPLICATIONS

[02]. This application is claims the benefit of priority of U.S. Provisional Patent Application No.62/070,138, Attorney Docket No. FSS5009USPSP, filed August 14, 2014, U.S. Provisional Patent Application No. 62/070,122, Attorney Docket No. FSS5010USPSP, filed August 14, 2014, and U.S. Provisional Patent Application No. 62/070,139, Attorney Docket No. FSS5011USPSP, filed August 14, 2014, the entirety of which applications, to the extent not inconsistent with this disclosure, are hereby incorporated by reference into this application.

[03]. BACKGROUND

[04]. 1. Technical Field

[05]. The invention relates to the field of medical devices, and more particularly medical devices or delivery systems thereof that have an elongated shaft which needs to be translated exactly a specific, but unknown distance with respect to a handle without using visual or tactile feedback to do so.

[06]. In some applications, the invention relates to systems for delivering a self-expandable intraluminal graft ("stents") for use within a body passageway or duct which are particularly useful for repairing blood vessels narrowed or occluded by disease.

[07]. 2. Related Devices and Methods

[08]. Transluminal prostheses have been widely used in the medical arts for implantation in blood vessels, biliary ducts, or other similar organs of the living body. These prostheses are commonly known as stents and are used to maintain, open, or dilate tubular structures. An example of a commonly used stent is given in U.S. Patent 4,733,665 filed by Palmaz on November 7, 1985, which is hereby incorporated herein by reference. Such stents are often referred to as balloon expandable stents. Typically the stent is made from a solid tube of stainless steel. Thereafter, a series of cuts are made in the wall of the stent. The stent has a first smaller diameter which permits the stent to be delivered through the human vasculature by being crimped onto a balloon catheter. The stent also has a second, expanded diameter, upon the application, by the balloon catheter, from the interior of the tubular shaped member of a radially, outwardly extending.

[09]. However, such stents are often impractical or use in some vessels such as the carotid artery or the superficial femoral artery. The carotid artery is easily accessible from the exterior of the human body, and is often visible by looking at ones’ neck. A patient having a balloon expandable stent made from stainless steel, or the like, placed in their carotid artery might be susceptible to severe injury through day-to-day activity. A sufficient force placed on the patient’s neck, such as by falling, could cause the stent to collapse resulting in injury to the patient. In order to prevent this and to address other shortcomings of balloon expandable stents, self-expanding stents were developed. Self-expanding stents act like springs and will recover to their expanded or implanted configuration after being crushed.

[10]. One type of self-expanding stent is disclosed in U.S. Patent 4,665,771, which stent has a radially and axially flexible, elastic tubular body with a predetermined diameter that is variable under axial movement of ends of the body relative to each other and which is composed of a plurality of individually rigid but flexible and elastic thread elements defining a radially self- expanding helix. This type of stent is known in the art as a "braided stent" and is so designated herein. Placement of such stents in a body vessel can be achieved by a device which comprise an outer catheter for holding the stent at its distal end, and an inner piston which pushes the stent forward once it is in position.

[11]. Other types of self-expanding stents use alloys such as Nitinol (Ni-Ti alloy) which have shape memory and/or superelastic characteristics in medical devices which are designed to be inserted into a patient's body. The shape memory characteristics allow the devices to be deformed to facilitate their insertion into a body lumen or cavity and then be heated within the body so that the device returns to its original shape. Superelastic characteristics on the other hand generally allow the metal to be deformed and restrained in the deformed condition to facilitate the insertion of the medical device containing the metal into a patient's body, with such deformation causing the phase transformation. Once within the body lumen the restraint on the superelastic member can be removed, thereby reducing the stress therein so that the superelastic member can return to its original un-deformed shape by the transformation back to the original phase, or close to it (as the implanted shape is designed to have some deformation to provide a force to prop open the vessel in which it is implanted).

[12]. Alloys having shape memory/superelastic characteristics generally have at least two phases. These phases are a martensitic phase, which has a relatively low tensile strength and which is stable at relatively low temperatures, and an austenitic phase, which has a relatively high tensile strength and which is stable at temperatures higher than the martensitic phase.

[13]. When stress is applied to a specimen of a metal such as Nitinol exhibiting superelastic characteristics at a temperature above which the austenite is stable (i.e. the temperature at which the transformation of martensitic phase to the austenite phase is complete), the specimen deforms elastically until it reaches a particular stress level where the alloy then undergoes a stress-induced phase transformation from the austenitic phase to the martensite phase. As the phase transformation proceeds, the alloy undergoes significant increases in strain but with little or no corresponding increases in stress. The strain increases while the stress remains essentially constant until the transformation of the austenite phase to the martensite phase is complete. Thereafter, further increase in stress is necessary to cause further deformation. The martensitic metal first deforms elastically upon the application of additional stress and then plastically with permanent residual deformation.

[14]. If the load on the specimen is removed before any permanent deformation has occurred, the martensitic specimen will elastically recover and transform back to the austenite phase. The reduction in stress first causes a decrease in strain. As stress reduction reaches the level at which the martensitic phase transforms back into the austenite phase, the stress level in the specimen will remain essentially constant (but substantially less than the constant stress level at which the austenite transforms to the martensite) until the transformation back to the austenite phase is complete, i.e. there is significant recovery in strain with only negligible corresponding stress reduction. After the transformation back to austenite is complete, further stress reduction results in elastic strain reduction. This ability to incur significant strain at relatively constant stress upon the application of a load and to recover from the deformation upon the removal of the load is commonly referred to as superelasticity or pseudoelasticity. It is this property of the material which makes it useful in manufacturing tube cut self-expanding stents. The prior art makes reference to the use of metal alloys having superelastic characteristics in medical devices which are intended to be inserted or otherwise used within a patient's body. See for example, U.S. Pat. No.4,665,905 (Jervis) and U.S. Pat. No.4,925,445 (Sakamoto et al.).

[15]. Designing delivery systems for delivering self-expanding stents has proven difficult.

One example of a prior art self-expanding stent delivery system is shown in U.S. Patent 4,580,568 issued to Gianturco on April 8, 1986. This reference discloses a delivery apparatus which uses a hollow sheath, like a catheter. The sheath is inserted into a body vessel and navigated therethrough so that its distal end is adjacent the target site. The stent is then compressed to a smaller diameter and load into the sheath at the sheath's proximal end. A cylindrical flat end pusher, having a diameter almost equal to the inside diameter of the sheath is inserted into the sheath behind the stent. The pusher is then used to push the stent from the proximal end of the sheath to the distal end of the sheath. Once the stent is at the distal end of the sheath, the sheath is pulled back, while the pusher remain stationary, thereby exposing the stent and expanding it within the vessel.

[16]. A conventional delivery system for a self-expanding stent is a so-called“pin and pull” system. The following is an example of a“pin and pull” system. The delivery system includes an outer sheath, which is an elongated tubular member having a distal end and a proximal end and a lumen therethrough. A typical outer sheath is made from an outer polymeric layer, an inner polymeric layer, and a braided reinforcing layer between the inner and outer layers. The reinforcing layer is more rigid than the inner and outer layers. It is this outer sheath which is “pulled” in the“pin & pull” system. The“pin & pull” system further includes an inner shaft located coaxially within the outer sheath. The shaft has a distal end, extending distal of the distal end of the sheath, and a proximal end, extending proximal of the proximal end of the sheath. It is this shaft which is“pinned” in the“pin & pull” system. A“pin & pull” system further has a structure to limit the distal motion of the self-expanding stent relative to the shaft. This“stent stopping” structure is located proximal to the distal end of the sheath. Lastly, a“pin & pull” system includes a self-expanding stent located within the sheath. The stent in its reduced diameter state for delivery makes frictional contact with the inner diameter of the outer sheath, more specifically, with the inner diameter of the inner layer of the outer sheath. The stent is located between the stop structure and the distal end of the sheath, with a portion of the shaft disposed coaxially within a lumen of the stent. The stent makes contact with the stop structure during deployment as the sheath is withdrawn and moves the stent with it (due to the frictional contact between the stent and the inner diameter of the sheath). The proximal motion of the proximal end of the stent is stopped as it comes into contact with the stop structure and the stop structure provides a counteracting force on the stent, equal and opposite to the frictional force from the sheath on the stent.

[17]. To deploy a stent from a“pin & pull” system, the system is navigated to the treatment location. Then the inner shaft, which extend proximal of the proximal end of the outer sheath is held fixed against the patient with one hand of the operator (physician). This action fixes the location of the inner shaft longitudinally with respect to the patient’s lumen being stented. This action is the“pin” step in the“pin & pull” system. The physician takes his or her other hand and pulls the outer sheath proximally (drawing some of it out of the patient toward the “pinning” hand) to expose and deploy the stent. This action is the“pull” step in the“pin & pull” system.

[18]. An early example of another“pin & pull” system is the Gianturco stent delivery system as described in U.S. Patent 4,580,568. In prior art delivery system, the outer sheath is a tube of a single material, and does not have a reinforcing structure within it. Also, the inner shaft is a tubular member which terminated immediately proximal to the reduced diameter stent at the distal end of the outer sheath. Deployment of the stent is accomplished by holding the inner shaft fixed with respect to the patient’s body and pulling back on the sheath to expose the stent, which expands upon removal of the radially restraining force, as illustrated in FIGS. 4 & 5 of U.S. Patent 4,580,569, which are incorporated herein by reference.

[19]. Many conventional self-expanding stents are designed to limit the stent foreshortening to an amount that is not appreciable (e.g., less than 10%). Stent foreshortening is a measure of change in length of the stent from the crimped or radially compressed state as when the stent is loaded on or in a delivery catheter to the expanded state. Percent foreshortening is typically defined as the change in stent length between the delivery catheter loaded condition (crimped) and the deployed diameter up to the maximum labeled diameter divided by the length of the stent in the delivery catheter loaded condition (crimped), multiplied by 100. Stents that foreshorten an appreciable amount (e.g., equal to or more than 10%) can be more difficult to deploy where intended when being deployed in a body lumen or cavity, such as a vessel, artery, vein, or duct. The distal end of the stent has a tendency to move in a proximal direction as the stent is being deployed in the body lumen or cavity. Foreshortening may lead to a stent being placed in an incorrect or suboptimal location. Delivery systems that can compensate for stent foreshortening would have many advantages over delivery systems that do not.

[20]. When a self-expanding stent is deployed in the vessel in an unintended location, an additional stent may be required to cover the full length of the disease portion of the vessel, and some stent overlap may occur. Obviously, the ability to reposition a stent to correctly deploy it in the intended location is preferred. Often, repositioning a stent requires that the stent first be reconstrained within the outer tubular member of the delivery system (often referred to as a “sheath”). To reconstrain a stent, the outer tubular member is pushed distally to slide over the stent and radially compress it back to its crimped diameter. To resist the axial force of the sheath on the stent due to friction, the proximal end of the stent which is still in the sheath is typically restrained from distal motion relative to the sheath and inner member.

A prior art delivery system that permits reconstraining of the partially deployed stent to allow the physician to reposition the delivery system and re-initiate the deployment process. The delivery system includes a stent lock that interfaces with the proximal portion of the stent. The stent lock is positioned about the inner shaft,“floats” around the inner shaft, and can linearly translate between a distal stop and a proximal stop and can also rotate in either direction about the inner shaft. The distance between the distal stop and the proximal stop should be at least equal to the maximum anticipated foreshortening for the stent to be delivered. The distance between the distal stop and the proximal stop may preferably be greater than that to be assured to not over constrain the system, due to movement of the inner shaft relative to the patient’s body. The proximal stop can either be fixed on the inner shaft, or can be a separate tubular member positioned about the inner shaft. Operating this system to fully deploy a stent or to reconstrain (if desired) a partially deployed stent requires additional steps than the standard “pin & pull” process of many commercially available delivery systems for self-expandable stents for the peripheral vasculature. Specifically, because the stent lock is“floating” between the distal and proximal stops there may be a longitudinal gap between the stent lock and either stop. To ensure that the proximal end of the stent is axially supported to counteract forces on the stent during deployment or reconstraining, the“gap” must be closed prior to retracting or advancing the sheath over the stent. Because this gap is within the sheath and within the body, it cannot be directly seen visually, and the length cannot be determined. Seeing it on the fluoroscope is not always easily accomplished either. Accordingly, this“gap management” requires interpreting tactile sensation that the stent lock is in contact with one of the stops (whichever one is needed to counteract the force to be applied to the stent via the sheath). The change in tactile sensation is not great and therefore can easily be missed. Accordingly, an opportunity exists to improve repeatability and user success with a system having this“gap” that needs to be closed prior to deployment or reconstraining.

[21]. This disclosure describes a user interface that removes the need to see or feel the“fact” that the gap has closed. The mechanism described herein requires a known, repeatable step to close a gap that can vary in length that makes the variation in the gap“invisible” to the user.

[22]. SUMMARY OF THE INVENTION

[23]. This disclosure describes a gear train converting a known angle of rotation of an input about a first axis into a variable distance of translation of an output along a second axis perpendicular to the first.

[24]. This disclosure describes a gear train able to convert a known angle of rotation about a central Z axis of an input gear into a linear translation of an output rack (which is selectively fixedly coupled to an elongated shaft) in a direction on the Y axis, the distance of which translation is limited by resistance to translation in that direction above a predetermined force or a maximum permitted distance, whichever occurs first.

[25]. This disclosure describes a gear train able to convert a known angle of clock wise rotation about a central Z axis of an input gear into a translation of an output rack (which is selectively fixedly coupled to an elongated shaft) in a distal direction on the Y axis, the distance of which translation is limited by resistance to translation in that direction above a predetermined force or a maximum permitted distance, whichever occurs first. [26]. This disclosure describes a gear train able to convert a known angle of counter- clockwise rotation about a central Z axis of an input gear into a translation of an output rack (which is selectively fixedly coupled to an elongated shaft) in a proximal direction on the Y axis, the distance of which translation is limited by resistance to translation in that direction above a predetermined force or a maximum permitted distance, whichever occurs first.

[27]. This disclosure describes a gear train able to convert a known angle of rotation in a first direction about a central Z axis of an input gear into a translation of an output rack (which is selectively fixedly coupled to an elongated shaft) in a first direction on the Y axis, the distance of which translation is limited by resistance to translation in that first direction above a predetermined force or a maximum permitted distance, whichever occurs first, and this gear train then can convert an equal angle of rotation in the opposite direction about a central Z axis of an input gear into a translation of an output rack (which is selectively fixedly coupled to an elongated shaft) in the opposite direction on the Y axis, the distance of which translation is limited by resistance to translation in that direction above a predetermined force or a maximum permitted distance, whichever occurs first.

[28]. This disclosure describes a gear train able to convert 180 degrees of rotation about a central Z axis of an input gear into a linear translation of an output rack (which is selectively fixedly coupled to an elongated shaft) in a direction on the Y axis, the distance of which translation is limited by resistance to translation in that direction above a predetermined force or a maximum permitted distance, whichever occurs first.

[29]. This disclosure describes a gear train able to convert 180 degrees of clock wise rotation about a central Z axis of an input gear into a translation of an output rack (which is selectively fixedly coupled to an elongated shaft) in a distal direction on the Y axis, the distance of which translation is limited by resistance to translation in that direction above a predetermined force or a maximum permitted distance, whichever occurs first.

[30]. This disclosure describes a gear train able to convert 180 degrees of counter-clockwise rotation about a central Z axis of an input gear into a translation of an output rack (which is selectively fixedly coupled to an elongated shaft) in a proximal direction on the Y axis, the distance of which translation is limited by resistance to translation in that direction above a predetermined force or a maximum permitted distance, whichever occurs first.

[31]. This disclosure describes a gear train able to convert 180 degrees of rotation in a first direction about a central Z axis of an input gear into a translation of an output rack (which is selectively fixedly coupled to an elongated shaft) in a first direction on the Y axis, the distance of which translation is limited by resistance to translation in that first direction above a predetermined force or a maximum permitted distance, whichever occurs first, and this gear train then can convert 180 degrees of rotation in the opposite direction about a central Z axis of an input gear into a translation of an output rack (which is selectively fixedly coupled to an elongated shaft) in the opposite direction on the Y axis, the distance of which translation is limited by resistance to translation in that direction above a predetermined force or a maximum permitted distance, whichever occurs first.

[32]. This disclosure describes a medical device including a shaft connected to the rack of any of the above described gear trains and an input knob coupled to the ring gear of the same gear train, such that rotation of the input knob about a Z axis transmits force through the gear train resulting in translation of the shaft in along a Y axis.

[33]. These and other features, benefits, and advantages of the present invention will be made apparent with reference to the following detailed description, appended claims, and accompanying figures, wherein like reference numerals refer to structures that are either the same structures, or perform the same functions as other structures, across the several views.

[34]. BRIEF DESCRIPTION OF THE FIGURES:

[35]. The figures are merely exemplary and are not meant to limit the present invention.

[36]. FIG.1 is a side view schematic of an idealized gear train.

[37]. FIG. 2 illustrates a side view of an enlarged partial detail of an embodiment of the interface between the first (upper) spur gear and the second (lower) spur gear, such as those idealized in FIG.1.

[38]. FIG.3 illustrates a top view of the idealized gear train of FIG.1. [39]. FIG. 4 illustrates a top view of an enlarged partial detail of an embodiment of the interface between the internal ring gear and the first (upper) spur gear, such as those idealized in FIG.3.

[40]. FIG. 5 illustrates a top view of an enlarged partial detail of an embodiment of the interface between the rack and the second (lower) pinion gear, such as those idealized in FIG.3.

[41]. FIG. 6 illustrates a central vertical cross-section of an embodiment of the interfacing top and bottom surfaces of the first (upper) and second (lower) idealized gears in contact with one another.

[42]. FIG. 7 illustrates a perspective view of another embodiment of the upper spur gear idealized in FIG.2.

[43]. FIG. 8 illustrates a perspective view of another embodiment of the lower spur gear idealized in FIG.2 that would interface with the upper spur gear of FIG.7.

[44]. FIG. 9 is a perspective view of an embodiment of the coupling between a shaft and the rack, such as the one idealized in FIGS.1 and 3.

[45]. FIG.10 is the same perspective view of only the rack of FIG.9.

[46]. FIG. 11 is a cross-sectional view of an embodiment of a gear train, such as the one idealized in FIG.3, and its carrier, along the view line P-P of FIG.3.

[47]. FIG. 12 illustrates a top view of the bottom half of an embodiment of the housing in which an embodiment of the rack is in its proximal most position.

[48]. FIG. 13 is a top view of the bottom half of the housing and rack of FIG. 12, but with the rack in its distal most position.

[49]. FIG.14A illustrates a top view of an input knob.

[50]. FIG.14B illustrates a side view of the input knob of FIG.14A

[51]. FIG. 15 a back, transverse cross sectional view of an embodiment of the housing with an input knob, the gear train, and the shaft coupled to the rack.

[52]. FIG.16 illustrates a top view of a portion of the top the housing with an input knob for embodiments where the input knob does not need to translate.

[53]. FIG. 17 illustrates a self-expanding stent delivery system including a gear train consistent with the present invention. [54]. FIGS. 18 A– 24A form a series of top views of a handle with a gear train consistent with the present invention being used to partially deploy a stent (by retracting the sheath) in figures 18A-21A and reconstrain the stent (by advancing the sheath) in figures 21A-24A

[55]. FIGS. 18B– 24B are a series of corresponding top views of the distal tip of the same device.

[56]. FIG. 25 is a schematic of a stent that has an appreciably longer length in its crimped state, in its crimped state.

[57]. FIG. 26 is a schematic of a stent that has an appreciably shorter length in its maximum designed expanded state, in its maximum designed expanded state.

[58]. FIGS. 27A-D are illustrations of closing the gap before deploying, deploying, closing the gap before reconstraining, and reconstraining using a delivery system without a mechanism to“manage” (close) the gap.

[59]. FIGS. 28A-D are illustrations of closing the gap before deploying, deploying, closing the gap before reconstraining, and reconstraining using a delivery system with a mechanism to “manage” (close) the gap. The gear trains described within are variations of one such mechanism to“manage” (close) the gap.

[60]. DETAILED DESCRIPTION

[61]. FIG. 1 is side view schematic of a gear train 10. Gear train 10 has an internal annular gear 12, also referred to as an internal ring gear 12, which has a central axis W. Ring gear 12 has a pitch circle of radius R_A. Gear train 10 has a first spur gear, also called a pinion gear 14. First spur gear 14 has a pitch circle of radius R_B about a central axis T. Central axis T and central axis W are parallel, and are, in this figure, are parallel to the“Z” axis. The pitch circle of first spur gear 14 is tangent to the pitch circle of ring gear 12. When the teeth of each of the ring gear and first spur gear are engaged, they rotate in the same direction about their respective central axes. First spur gear 14 extends below internal ring gear 12. First spur gear 12 is above second spur gear 16, and is in contact with second spur gear 16. A bias force providing structure 18 is illustrated below second spur gear 16, and provides a force against spur gear 14 to bias it into contact with spur gear 12. The interface of the two spur gears provides a clutch that is torque limited. When the torque transmitted from one spur gear to the other spur gear is less than or equal to a set value, the gears rotate with the same angular velocity. When the torque transmitted from one spur gear to the other spur gear exceeds the set value, the clutch releases and the two gears do not rotate with the same angular velocity. The set value is set by a known compression of the spring (which is one embodiment of a bias force providing structure 18).

[62]. Second spur gear 16 has a pitch circle of radius R_C about its central axis, which is the same as axis T. The pitch circle of second spur gear 16 is tangent to the pitch“line” of linear gear 22, also known as a rack 22. When internal ring gear 12 rotates about axis W, rack 22 linearly translates parallel to the“Y” axis in or out of the page (depending on whether the internal ring gear rotates counter-clockwise or clockwise). Bias force providing structure 18 exerts an equal and opposite force on the“ground” 20.

[63]. FIG. 2 is an enlargement of detail A of FIG.1, showing a side view of an embodiment of the clutch interface between upper gear 24 and lower gear 26. As illustrated the interface has peaks 28 and valleys 30.

[64]. FIG.3 is a top view schematic of the gear train 10. Bias providing force 18 and ground 20 are not shown for ease of understanding the other aspects of the gear train. Detail B of FIG. 3 may be seen in FIG. 4 and detail C of FIG.3 may be seen in FIG.5, and cross-sectional view P-P may be seen in FIG.11.

[65]. FIG.4 illustrates an enlarged detail of a top view of embodiments of idealized gears 12 and 14 with teeth. Internal ring gear 32 has teeth 36 which are illustrated engaged with teeth 38 of upper spur gear 34.

[66]. FIG. 5 illustrates an enlarged detail of a top view of embodiments of idealized gear 16 and rack 22 with teeth. Second spur gear 40 has teeth 46 which are engaged with teeth 48 of rack 44.

[67]. FIG. 6 illustrates embodiments of gears 14 and 16 (idealized without teeth, but just cylinders at the pitch circles) with one configuration for the clutch interface. In this embodiment, upper spur gear 50 interfaces with lower spur gear 52 along mating frusto-conical surfaces. Upper gear 50 has a larger diameter cylindrical recess in its top surface and a smaller diameter cylindrical through-hole aligned with the central axis T (not shown). The larger diameter recess permits a fastener (not shown) to capture annular surface 54 and prevent upward motion in the“Z” direction. Typically to reduce the torque exerted by such a fastener, the cylindrical wall 56 of the recess is dimensioned larger than the fastener. The shank of the fastener extends through the smaller diameter through hole defined by cylindrical wall 57. The bottom surface 58 of upper gear 50 is a frusto-conical surface, tapering from the lowest point to where it intersects the cylindrical wall 57. Lower spur gear 52 has a through hole of the same diameter, defined by cylindrical wall 62. The top surface 60 of the lower gear 52 is a frusto- conical surface tapering from the pitch circle to the highest point where it intersects with cylindrical wall 62. Bottom surface 58 and top surface 60 are mating surfaces, which are held in contact with one another through the force from the bias force providing member 18 and, in any opposing force from the fastener on annular surface 54.

[68]. FIG. 7 illustrates a perspective view including the bottom surface of another embodiment of the upper spur gear 14, as illustrated in FIG. 2. Here the surface geometry resulting in the top portion of“peak” 28 from FIG. 2 can been seen, point 28A corresponds to the point on the OD of the upper spur gear at peak 28 when mating, as well as point 30A which corresponds to the point on the outer diameter of the lower spur gear at valley 30 when mating.

[69]. FIG. 8 illustrates a perspective view including the top surface of another embodiment of the lower spur gear 16, as illustrated in FIG. 2. Lower spur gear 16 has a lower cylindrical portion with teeth (not shown—still shown as a cylinder at the pitch circle radius) 40 and an upper cylindrical portion of smaller diameter (the same outer diameter as upper spur gear 14 in FIG. 7) with a top circular fluted surface with the bottom portion of“peak” 28 from FIG. 2 visible as point 28B and the bottom portion of“valley” 30 from FIG. 2 visible as point 30B on the outer diameter.

[70]. FIG.9 illustrates the coupling between shaft 64 with central longitudinal axis M and an embodiment of rack 22. As illustrated, the proximal end of shaft 64 is surrounding by coupling flag 66, which is fixedly secured to shaft 64 by adhesive or other means known to those of skill in the art. Coupling flag 66 sits in a mating recess in rack 44 to ensure orientation remains accurate as well as being fastened to the bottom of rack 44. [71]. FIG. 10 illustrates the mating recess 68 in rack 44 and optional through hole 69 for a fastener.

[72]. FIG.11 illustrates a vertical cross-sectional view along the view line P-P of FIG.3, but also includes a carrier not illustrated in FIG. 3. Assembly 100 includes an embodiment 70 of internal ring gear 12. Internal ring gear 70 includes additional structure, but retains a pitch circle for teeth to engage the first spur gear 72. The pitch circle of internal ring gear 70 has a radius marked as R_A about central axis T. Embodiment 70 has curved surfaces 86 which limit the Z and X motion of assembly 100 within a housing (not shown). Assembly 100 includes an embodiment 72 of upper spur gear 14. Upper spur gear 72 has a pitch circle of radius B marked as R_B. The pitch circle of upper spur gear 72 is tangent to the pitch circle of internal ring gear 70 (not visible, but directly behind the spur gear in the same vertical plane with central axis T. Upper spur gear 72 is in contact with an embodiment 74 of lower spur gear 16, with mating surfaces such as those illustrated in FIGS.7 & 8. Lower spur gear has a pitch circle of radius C which is marked as R_C. An embodiment 76 of a bias force providing structure 18 is a coil spring. Spring 76 is compressed between a bottom surface of lower spur gear 74 and an upward facing surface of carrier 78, which is a form of relative ground 20, by the engagement of fastener 80 and carrier 78. Such fixed attachment may be through press fit in section 82, screw threads along section 82 or other fastening means known to one of skill in the art. Lower spur gear 74 is partially surrounded by carrier 78 in a recess 90. Lower spur gear’s engagement with rack 22 is not shown here, but is best seen in FIG. 3. Carrier 20 may slide within a housing and the bottom surface 84 of runners may contact the internal surface of the housing to form another relative ground (i.e., the housing may be moved in the environment relative to absolute “ground”, since a preferred housing is the handle of a medical device).

[73]. FIG. 12 illustrates a top view of the bottom half of an embodiment of the housing 102 in which an embodiment of rack 44 with teeth 48 is in its proximal most position. Central longitudinal axis M of the shaft (not shown) is illustrated to show the line of travel. A space between the distal end of rack 44 and the distal end of receiving groove in bottom half 102 of the housing is marked as having the a length“G”. [74]. FIG. 13 is a top view of the bottom half of the housing and rack of FIG. 12, but with rack 44 in its distal most position, after having traveled the length“G”, creating a space between the proximal end of rack 44 and the proximal end of the receiving groove in bottom half 102 of the housing. The length of the space in the line of travel is marked with a“G” in the figure.

[75]. FIG. 14A illustrates a top view of an input knob 94 with a raised portion 96 for gripping and an arrow indicator 98 visible on a top surface of cylindrical portion 104. By applying a torque to knob 94, it may be turned clockwise, shown by arrow 106, or counterclockwise, shown by arrow 108, about central axis W.

[76]. FIG.14B illustrates a side view of the input knob of FIG.14A. Raised portion 96 rises above cylindrical portion 104. Additional features may be added to assist in connecting it to the internal ring gear, as it may be desirable to have the input knob be outside of a housing that encompasses a gear train consistent with the present invention.

[77]. FIG. 15 illustrates a back view and partial transverse cross-section of a housing assembly 110 including a gear train and rack of the present invention. Housing assembly, in this embodiment includes top shell 101 and bottom shell 102. Top shell 101 has an elongated opening parallel to a longitudinal axis of housing assembly (parallel to the Y axis). Input knob 108 is connected to a small diameter portion extending in the Z direction through the opening in top shell from the internal ring gear 70. Bottom shell 102 is attached to top shell 101 to provide a housing that a user may grasp and use as a handle. Components of the gear train are shown without a carrier for ease of illustration and understanding. (Carrier 20 is illustrated with some of these components in FIG. 11) The X-Z plane of the illustrated cross section includes central axis W of ring gear 70 and central axis T of spur gears 72 and 74 and shows the perpendicular central longitudinal axis M of shaft 64, which rack 44 translates parallel to.

[78]. FIG. 16 illustrates a top view of an input knob above a housing containing a gear train consistent with the present invention. The input knob is coupled to the internal ring gear through a hole in the housing. In this embodiment, the input knob (and the circular gears of the gear train do not translate with respect to the housing. Any slot need for translation of other portions of the medical devices may be located elsewhere on the housing, for example, distally of the input knob for the gear train. [79]. FIG. 17 illustrates a“pin and pull” self-expanding stent delivery system. A guide wire 340 is shown extending proximally from the proximal end of handle 322. The distal end of guide wire 340 is shown extending distally from the distal end of a distal tip 346 attached (or a part of) first shaft 326. The sheath or outer member 328 extends distally from a Y-connector and has a distal end 344 in contact with distal tip 346. A self-expanding stent 350 is located within the lumen of sheath 328 near distal end 344. An optional third shaft 342 is illustrated with a distal end located proximally of stent 350. Self-expanding stent 350 is in contact with the inner walls of sheath 328. A ring 348, which acts as a proximal stop for self-expanding stent 350, is attached to shaft 326. When sheath 328 is withdrawn proximally, friction between the stent 350 and the shaft 328 tends to pull the stent 350 proximally. Ring 348 mechanically interferes with the stent 350 and prevents it from moving past ring 348.

[80]. Figures 18A-24B illustrate snapshots in the operation of an embodiment of a medical device consistent with the present invention. The“A” figures illustrate the position of the input knob in handle assembly and the overall motion that the knob is in the process. The“B” figures illustrate the corresponding state of parts of the distal portion of delivery system and the self- expanding stent in the vessel (body lumen).

[81]. In operation, a self-expanding stent delivery system 200 might come“out of the box” with the input knob 94 at the distal end of a slot 202 and oriented with the arrow indicator 204 pointing distally. See FIG.18A. This may correspond to a distal end configuration as shown in FIG. 18B. The distal end 206 of the sheath 208 may surround at least a portion of the distal tip 210 (dilator) of the inner shaft 212. The stent 214 may be at a reduced (crimped or compressed) diameter within the lumen of sheath 208 near distal end 206 of sheath 208. In FIGS.18B, stent 214 is illustrated smaller than the inner diameter of sheath 208 for ease of visualization. However, typically, self-expanding stents 214 are in contact with the inner diameter of sheath 208.

[82]. After insertion of the distal portion into the patient with stent 214 positioned in the vasculature at the intended location for deployment, any“gap” between stent lock 216 and proximal stop 218 is closed by in-line translation distally of the inner shaft 212 until proximal stop 218, which is in fixed longitudinal relation to inner shaft 212, comes in contact with the proximal end of stent lock 216. See FUG, 19A, Closing the gap is also known as managing the gap. In the illustrated embodiment, gap management prior to deployment is accomplished by rotating input knob 94 clockwise (when viewed from the top) 180 degrees until arrow indicator 204 is pointing proximally. See FIGS, 19A (ending with the position in FIG. 20A). For embodiments of the medical device which have a gear train according to the present invention coupled to the input knob, this clockwise rotation through 180 degrees linearly translates inner shaft 212, which is longitudinally fixedly coupled to the rack (e.g., as in FIGS. 9 and 15), to close any gap less than or equal to the maximum designed distance. After proximal stop 218 is in contact with the proximal end of stent lock 216, the“sheath” 208 is retracted by applying a force in the proximal direction to input knob 94, which linearly translates the“sheath” 208 proximally any distance less than or equal to the slot length in the handle assembly. See FIG. 20A. After the distal end of the radially compressed stent 214 is exposed, the exposed portion of the stent radially expands and makes contact with the vessel wall. See. FIG. 20B. As the stent radially expands, the length of the expanded portion of the stent decreases, which is called “foreshortening.” Because the distal end is in contact with the vessel wall with greater friction than in the sheath, it does not move relative to the patient, and if the inner shaft has been held in fixed longitudinal relation with the patient, then the proximal end of the stent moves distally within the sheath, which results in the stent lock translating distally. See FIG. 20B. (Note, the stent lock may also rotate in one and then the other direction about the longitudinal axis of the inner shaft, depending on the stent geometry.) As the sheath is further retracted, more and more of the stent is exposed, expands, and foreshortens. See FIG. 21B. If the physician decides that the stent is not in an optimal position longitudinally in the vessel, as long as the sheath still contains the portion of the stent interfacing with the stent lock, the deployment may be stopped and reversed to“reconstrain” the stent. (FIGS. 22A– 24A, 22B– 24B) This may alternatively called“recapturing” the stent. After stopping the deployment, see FIG. 21A, 21B, which entails removing the proximal force on the input knob, the next step is to support the stent lock 216 on the distal end, so that it can counter the distal forces placed on the stent by the friction between the distally moving sheath as it is advanced. If there is a gap between the distal stop 220 and the stent lock 216, it may be closed or managed by in-line translation of the inner shaft 212 proximally to bring to the distal stop 220 in contact with the stent lock 216. In the illustrated embodiment, the gap may be managed (closed) preferably by rotating the input knob counter- clockwise 180 degrees until the arrow indicator is pointing distally. See FIG.22A, ending in the position illustrated in FIG. 23A. For embodiments of the medical device which have a gear train according to the present invention coupled to the input knob, this counter-clockwise rotation (as viewed from above) through 180 degrees linearly translates the inner shaft proximally, which is longitudinally fixedly coupled to the rack, to close any gap less than or equal to the maximum designed distance. See FIG. 22B. After the arrow indicator on the input knob is pointing distally, a distal force applied to the input knob, which is longitudinally fixedly coupled to a proximal portion of the sheath, linearly translates the input knob to the distal end of the slot in the handle assembly. See FIGS. 23A, 24A and 23B, 24B. The delivery system may then be repositioned longitudinally with in the vessel and the deployment process re-initiated, beginning, of course, with managing the gap by rotating the input knob to point in the direction of the desired sheath movement. See FIG. 19A. To completely deploy the stent the sheath is retracted past the stent lock, whereupon the stent disengages from the stent lock and can completely expand in the vessel.

[83]. FIGS. 25 and 26 are schematics of a crimped diameter and an expanded diameter, respectively, of a stent 214 that appreciable changes dimension with a change from delivery diameter (crimped) to deployed diameter. The circular objects 230 are radiopaque to assist physicians in seeing the distal and proximal ends of the stent on the fluoroscope during a procedure.

[84]. FIGS. 27A through 27D illustrate a method of using a modified“pin and pull” stent delivery and reconstraining system 240. The modification from FIG.17 is that the distal portion looks instead like the“B” series of figures in FIGS. 18-24. After stent delivery and reconstraining system 240 has been introduced to the vasculature, preferably through an introducer 242, outer member or sheath 208 is held stationary with respect to the patient with a user’s first hand (resting against the patient, typically a leg for femoral arterial access sites), and the user’s second hand grips the luer valve or other proximal end of inner member 212 and moves it distally with respect to sheath 208 until the proximal stop 218 (see FIGS.18B, 19B) is in contact with the proximal end of stent lock 216. Because this gap between the initial configuration (FIG. 18B) and the desired supportive position for deployment (FIG. 19B) is within sheath 208 and within the patient’s vasculature, it cannot be seen. Thus the user must move inner member or shaft 212 until he or she feels resistance, and concludes that the distal end of the proximal stop 216 (e.g., pusher tube in fixed relationship to inner member or ring fixedly mounted on inner member) is in contact and will support the stent lock, to resist stent 214 from moving proximally, during deployment. In FIG. 27B, the user then pins the inner member to the patient, and pulls sheath 208 proximally to expose stent 214 (See FIGS. 20B). As stent 214 has radiopaque markers, if the image on the fluoroscope shows that the placement of stent 214 is not as the user desires, the user can stop deploying and begin recapture or reconstraining (see FIG. 21B), if stent 214 still interfaces with stent lock 216 in the lumen of sheath 208. To begin recapture, the axial gap between distal stop 220 and stent lock 216 must be closed to permit distal stop 220 to support stent lock 216 as sheath 208 is being advanced distally. To do this, as illustrated in FIG. 27C, a user grips shaft 212 and pulls it proximally. Then the distal end is configured as in FIG. 22B. The user may now begin reconstraining by advancing sheath 208. Due to column strength characteristics of the system, a user may successfully advance sheath 208 by moving a somewhat tacky, flexible and resilient polymer member 244 (sometimes known as a grip) along the stationary sheath 208 and then deforming grip 244 around sheath 208 closer to introducer 242 to advance sheath 208 without buckling to reconstrain stent 214 (FIGS. 23B, 24B). It should be noted that a third hand is needed to pin inner member 212 to the patient or even supply a bit of“back tension” to inner member 212 to support stent 214 during reconstraining. To deploy the stent in the desired location, the steps must be repeated.

[85]. FIGS.28A-D illustrate the steps of FIGS.18A, B through 24A, B, as a user would grip the parts of handle assembly 250 of delivery system 200 after advancing it into the patient’s vasculature via introducer 242.

[86]. Ways of longitudinally constraining stents are known in the art and may include features fixedly attached to third shaft or features able to rotate and slide with respect to third shaft. Such features permit the proximal end of stent to be pulled on or held in position, permitting second shaft to be advanced distally“recapturing” a partially deployed stent.

[87]. It is with these“recapturable” stent delivery systems that the gear train described herein would have a significant use.

[88]. Aspects of the present invention have been described herein with reference to certain exemplary or preferred embodiments. These embodiments are offered as merely illustrative, not limiting, of the scope of the present invention. Certain alterations or modifications which are possible include the substitution of selected features from one embodiment to another, the combination of selected features from more than one embodiment, and the elimination of certain features of described embodiments. Other alterations or modifications may be apparent to those skilled in the art in light of instant disclosure without departing from the spirit or scope of the present invention, which is defined solely with reference to the following appended claims.

Claims

1. An intraluminal medical device comprising:

an elongate shaft having a proximal end and a distal end and a central longitudinal axis; a housing coupled to the proximal end of the elongate shaft; and

a gear train at least partially within the housing, the gear train including:

an internal ring gear of pitch circle radius A about a central axis, which axis is perpendicular to the central longitudinal axis of the proximal end of the elongate shaft;

a first spur gear, the first spur gear having a pitch circle radius B about a second axis parallel to the central axis of the internal ring gear, and a bottom surface, the pitch circle of the first spur gear tangent to the pitch circle of the internal ring gear;

a second spur gear having a pitch circle radius C about the second axis, and a top surface, wherein the top surface of the second spur gear is in contact with, and stationary relative to, the bottom surface of the first spur gear when a torque applied to one of the first and second spur gears is below a predetermined value; and

a translatable elongate rack disposed parallel to the central longitudinal axis of the elongate shaft, wherein the rack’s teeth are engaged with the second spur gear and the rack is fixedly coupled to a proximal portion of the elongate shaft,

2. The intraluminal medical device of claim 1, further comprising:

a second elongate shaft having a proximal end and a distal end, a lumen therethrough, and a central longitudinal axis,

wherein the first elongate shaft is at least partially disposed within the lumen of the second elongate shaft, and the proximal end of the second elongate shaft is distal to the proximal end of the first elongate shaft, the proximal portion of the second elongate shaft is disposed within the housing.

3. The intraluminal medical device of claim 2, wherein the proximal end of the second elongate shaft is fixed with respect to the central axis of the internal ring gear.

4. The intraluminal medical device of claim 1, further comprising:

an input knob coupled to the internal ring gear.

5. The intraluminal medical device of claim above, further comprising an arrow on the input knob.

6. The intraluminal medical device of claim 1, further comprising:

a spring biasing the second spur gear into contact with the first spur gear.