WO2016025896A1 - Medical device with single-input, multiple-output control knob - Google Patents

Abstract

A stent delivery system has a single-input, multiple-output control knob. A self-expanding stent delivery system with multiple co-axial shafts for deploying and optionally reconstraining partially deployed stents has a single control knob that can be rotated a fixed amount and translated to hold one of the multiple shafts fixed while the other is being translated, to lock out unintended motion in the system, and to close a gap that may exist between a support for the stent and a stent-lock.

Description

MEDICAL DEVICE WITH SINGLE-INPUT, MULTIPLE-OUTPUT CONTROL KNOB [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 two shafts, one partially within the other, which shafts need to move with respect to one another.

[06]. 2. Related Devices and Methods

[07]. Transluminal prostheses have been widely used in the medical arts for implantation in blood vessels, biliary ducts, or other similar lumens 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 in its entirety 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 force.

[08]. However, such stents are often impractical for 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 one’s neck. A patient having a balloon expandable stent made from stainless steel, or the like, placed in his or her 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.

[09]. 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.

[10]. 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 that 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“memorized” 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).

[11]. 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. [12]. 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.

[13]. 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.).

[14]. A now 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 proximal 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.

[15]. To deploy a stent from a“pin & pull” system, the system is navigated to the treatment location. Then the inner shaft, which extends proximal of the proximal end of the outer sheath is held fixed against the patient with one hand of the operator (medical professional). This action fixes the location of the inner shaft along a longitudinal axis of 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 unconstrain, expose, and deploy the stent. This action is the“pull” step in the“pin & pull” system.

[16]. An early example of another“pin & pull” system is the Gianturco stent delivery system as described in U.S. Patent 4,580,568 issued April 8, 1986. In this prior art delivery system, the outer sheath is a tube of a single material, which does not have a reinforcing structure within it. 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 or inner shaft is then used to push the stent from the proximal end of the sheath to the distal end of the 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 4,580,568, which are incorporated herein by reference.

[17]. 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 nominal deployed diameter (i.e., the labeled diameter which the stent is intended to have when deployed, i.e., a“10 mm stent” has a nominal deployed diameter of 10 mm.) 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 axially 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. And, in conditions where the distal end is stationary with respect to the vessel wall, the proximal end of the stent will move distally as a function of the foreshortening upon expansion. Thus 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.

[18]. 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 diseased 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 number of delivery system designs provide features to restrain the proximal end of the stent from distal motion, see, e.g., U.S. Patent Application Serial No. 12/573,527, Attorney docket number FSS5004USNP, filed October 5, 2009, and Serial No. 13/494,567, Attorney docket number FSS5004USCIP, filed June 12, 2012, and European Patent Publication No. 0696442 A2, and U.S. Patent Publication No.2007/0233224 A1.

[19]. SUMMARY OF THE INVENTION

[20]. This disclosure describes a multiple shaft linear translation control system with a single input and multiple outputs. A first shaft with a proximal and distal end and a length therebetween, and a second shaft with a proximal and distal end, a length therebetween, and a lumen therethrough are separately controlled by different devices which are controlled by a single input motion. A length of the first shaft is within the lumen of the second shaft, but a length remains longitudinally outside of the first shaft. In operation the second shaft needs to be held stationary relative to a frame and the first linearly translated with respect to the second shaft. In operation the first shaft needs to be held stationary relative to the frame and the second shaft linearly translated with respect to the first shaft. In operation the desired linear translation of the second shaft is at least a magnitude greater than the desired linear translation of the first shaft. A first device (gear train with torque limited clutch, described in more detail in concurrently filed PCT International Patent Application, attorney docket number FSS5009WOPCT, which is hereby incorporated by reference in its entirety) is coupled to the first shaft and a second device (simple rigid mechanical connection of sheath to“slider”) is coupled to the second shaft. A third device (rack decoupler, described in more detail in concurrently filed PCT International Patent Application, attorney docket number FSS5010WOPCT) enables the first and second device to be controlled by the same input motion. In some embodiments, the first, second, and third device are all controlled by the same input motion. In some embodiments the third device is controlled by a separate input motion. A fourth device (lock bar and one or more lock plates, described in concurrently filed PCT International Patent Application, attorney docket number FSS5008WOPCT) prevents the second sheath from being linearly translated in at least one direction accidently. In some embodiments the first, second, and fourth device are all controlled by the same input motion. In some embodiments, the first, second, third, and fourth device are all controlled by the same input motion.

[21]. One aspect of the present invention is a control knob having an internal ring gear of pitch circle radius A about a central axis, a first detent spaced at radius B about the central axis and facing in a first of the two possible directions defined by the central axis, a second detent spaced at radius B about the central axis and at a fixed angle from the first detent, and facing in the same direction as the first detent, an arcuate cam spaced at radius B about the central axis along the fixed arc between the first and second detents, wherein the cam faces in the same direction as the first and second detents, a first surface substantially in a first plane with the central axis or parallel to the central axis, the first surface for unlocking a lock mechanism to permit motion in a first direction perpendicular to the central axis, and a second surface substantially in a second plane with the central axis or parallel to the central axis for unlocking a lock mechanism to permit motion is a second direction perpendicular to the central axis, opposite the first.

[22]. Another aspect of the present invention is a stent delivery system including two or more elongated co-axial shafts having a central longitudinal axis, a handle assembly including a housing defining an elongated slot parallel to the central longitudinal axis of the one or more elongated co-axial shafts, a stent radially compressed in the lumen of an outer shaft of the two or more elongated co-axial shafts, the stent surrounding a length of an inner shaft of the two or more elongated co-axial shafts, a control knob rotatably and translatably coupled to the handle assembly and extending through the elongated slot defined by the housing. The control knob includes an external portion disposed external to the housing to be gripped, rotated, and translated by a user; and an internal portion disposed internal to the housing including an arcuate cam, an internal ring gear, and one or more lock plate actuators, wherein the control knob is operatively coupled to at least two of the two or more elongated co-axial shafts.

[23]. 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.

[24]. BRIEF DESCRIPTION OF THE FIGURES:

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

[26]. FIG.1 is a bottom view of a first embodiment of a control knob.

[27]. FIG.2 is a bottom view of a second embodiment of a control knob.

[28]. FIG.3 is a top view of a handle corresponding to a medical device with the first control knob.

[29]. FIG. 4 is a bottom view of an embodiment of a control knob in position with the structures of the four devices with which it interfaces and a lock bar to show relative position within a handle.

[30]. FIG.5 illustrates the parts shown in FIG.4 in a different configuration

[31]. FIG.6 illustrates the parts shown in FIG.4 in a second different configuration

[32]. FIG.7 illustrates the parts shown in FIG.4 in a third different configuration

[33]. FIG.8 illustrates the parts shown in FIG.4 in a fourth different configuration

[34]. FIG.9 illustrates the parts shown in FIG.4 in a fifth different configuration

[35]. FIG.10 illustrates the parts shown in FIG.4 in a sixth different configuration

[36]. DETAILED DESCRIPTION

[37]. FIG.1 is a bottom view of a first embodiment 10 of a control knob. With respect to this figure, increasing Z values are“into the page” and decreasing Z values are“out of the page” thus when a surface or structure is described as projecting or extending downward, the surface is “closer” to the viewer. Control knob 10 includes a vertical surface 12 extending downward from control knob 10 and facing in the negative Y direction (proximal). Face 12 is designed to contact a surface of a first locking plate, with reference to the incorporated application describing the same, and move it out of contact with the lock bar, permitting motion in a the positive direction along the Y axis (distally). Control knob 10 has a second vertical face 14 extending downward from control knob 10 and facing in the negative Y direction (proximally). Face 14 is designed to contact a surface of a second locking plate, with reference to the incorporated application describing the same, and move it out of contact with the lock bar, permitting motion in the negative direction along the Y axis (proximally).

[38]. As illustrated in FIG. 1, control knob 10 has a first detent 16 at a first radius from the center C of the control knob. The first detent 16 is a concave surface facing downward. Control knob 10 has a second detent 18 at the same radius as the first detent. The second detent faces the same way as the first detent. The first and second detents receive the top surface of the pin that pushes on the rockbar, referring to the incorporated application describing the same. The first and second detents are separated by 180 degrees. The bottom surface of the control knob 10 gradually extends down from detent 16 gradually along a ramp and then is planar and then rises gradually up a ramp to detent 18 along the arc 20 at the first radius. Arc 20 is the path that the top surface of the pin slides along as control knob rotates 180 degrees.

[39]. As illustrated in FIG.1, control knob 10 has an internal ring gear 10 that extends below the surface of arc 22. Internal ring gear 22 has two voids, of which A is the midpoint of one, and point B is the midpoint of the other, where there are no teeth or only partial teeth. These voids permit the upper spur gear to rotate when the control knob does not rotate, without releasing the torque limited clutch, with reference to the incorporated application describing these features.

[40]. As illustrated in FIG. 1, ring 24 projects downward from control knob 10 to form a connector for the rigid structure connecting the control knob and the sheath.

[41]. FIG. 2 is a bottom view of a second embodiment 26 of a control knob. The second embodiment is the same as the first embodiment except there are no voids on the internal ring gear. Teeth 28 are evenly distributed about internal ring gear 22. Thus when the knob does not rotate, but linearly translates to retract or advance the sheath, the upper spur gear does not move, and the torque-limited clutch releases to prevent the lower spur gear from rotating (as the rack is held stationary with respect to the handle while the sheath is linearly translated in either direction). This slipping of the clutch between the upper and lower spur gears can be felt and heard by users holding the knob and linearly translating it as clicking and vibration in the knob.

[42]. FIG. 3 is a top view of a handle 30 corresponding to a medical device with the first control knob. Top portion 32 of control knob 10 is shown in its distal most direction with the arrow indicator pointing distilling indicating that it can be moved only in a distal direction (which of course it can’t as there is no more room in the slot or handle to do so). From the distal end 36 of handle 30 extends a shaft 40. In some embodiments, shaft 40 may be a stationary third shaft. In some embodiments, shaft 40 may be a sheath which contains the constrained stent. Proximal end 38 of handle and elongated slot aligned with the central longitudinal axis of shaft 40 may been seen in FIG.3.

[43]. The remaining figures illustrate snap shots in a series of steps in using the control knob 10.

[44]. FIG. 4 is a bottom view of an embodiment of a control knob in position with the structures of the four devices with which it interfaces and a lock bar to show relative position within a handle. FIG. 4 shows a bottom view of a control knob 10 such as the one mounted in handle 30. Knob 10 interfaces with pin 42 and lock plate 44 and holds lock plate 44 in a position out of contact with lock bar 52. Lock plate 46 is locked on lock bar 52. Lock bar 52 has a distal end 48 and a proximal end 50. Knob 10 also interface with upper spur gear 46, shown here as a pitch circle. In this position, only distal motion along lock bar 52 is possible. Pin 42 is in detent 16 and spur gear 46 is in the void adjacent to point A on control knob 10.

[45]. FIGS 5-10 are the same bottom views of the parts shown in FIG. 4, but illustrate the rotation or linear translation of control knob 10 and the change in orientation of the other parts as a typical process of using this to partially deploy, then recontrain a stent. FIG. 10 is not a next step, but just illustrates the state of the parts once the stent has been fully deployed from the stent delivery system.

[46]. 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

[47]. CLAIMS

[48]. 1. A stent delivery system comprising:

two or more elongated co-axial shafts having a central longitudinal axis; a handle assembly including a housing defining an elongated slot parallel to the central longitudinal axis of the one or more elongated co-axial shafts;

a stent compressed in the lumen of an outer shaft of the two or more elongated co-axial shafts, the stent surrounding a length of an inner shaft of the two or more elongated co-axial shafts;

a control knob rotatably and translatably coupled to the handle assembly and extending through the elongated slot defined by the housing, the control knob comprising:

an external portion disposed external to the housing to be gripped, rotated, and translated by a user; and

an internal portion disposed internal to the housing including an arcuate cam, an internal ring gear, and one or more lock plate actuators, wherein the control knob is operatively coupled to at least two of the two or more elongated co-axial shafts.