Catheter steering systems with an overcenter assist mechanism and a locking mechanism

Abstract

A steering system (1) for manipulation of a distal end of a catheter (10), including catheters used for removal of objects, such as kidney stones, is disclosed. The steering system includes an overcenter assist mechanism (32). The steering system can include a locking mechanism (50).

Description

[0001] Attorney Ref: 125270.00051

[0002] CATHETER STEERING SYSTEMS WITH AN OVERCENTER ASSIST

[0003] MECHANISM AND A LOCKING MECHANISM

[0004] Inventor

[0005] Brian Y. Tachibana

[0006] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051

[0007] FIELD

[0008] The present inventions relate to steering systems for manipulating a distal end of a catheter, including catheters used for removal of objects, such as kidney stones. More particularly, the systems can include a steering mechanism, the operation of which causes bending of the distal end of the catheter, and an overcenter assist mechanism operably engaged with the steering mechanism for assisting operation of the steering mechanism by a user. The steering systems can also include a locking mechanism to lock in place the steering mechanism.

[0009] BACKGROUND

[0010] Kidney stones are a common medical problem that negatively impacts millions of individuals worldwide. Kidney stones include one or more solid masses of material that are usually made of crystals and form in parts of the urinary tract including in the bladder, the ureter, and / or the kidney. Kidney stones range in size from small (less than about 1 cm) to large (more than 4 cm) and may cause significant pain to the individual and damage to the kidney. The recommended treatment for removal of kidney stones varies according to numerous factors including the size of the kidney stones, the number of kidney stones, and the location of the kidney stones. The most common treatments for kidney stones are shock wave lithotripsy (ultrasound waves used to fracture the stones), ureteroscopy (fracture and removal of the stones using an endoscope that is introduced through the bladder), and percutaneous nephrolithotomy (fracture and removal of the stones using an endoscope that is introduced through a sheath placed through the patient's back into the kidney).

[0011] The large kidney stones are usually removed through percutaneous nephrolithotomy or nephrolithotripsy. In these procedures, a small incision is made through the patient's back adjacent to the kidney and a sheath is passed into the kidney to accommodate a larger endoscope used to fracture and remove stones. The stone may be removed directly through a tube or may be broken up

[0012] 1

[0013] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 into small fragments while still in the patient's body and then removed via a vacuum or other known methods.

[0014] There are numerous drawbacks associated with nephrolithotomy, nephrolithotripsy, and other invasive surgeries requiring an incision in the skin. Namely, such surgical techniques may require significantly more anesthesia administered to the patient, the surgeries are more complicated and pose a higher risk of infection and complications for the patient, and the surgeries require a substantial incision in the patient, which may leave a scar. Additionally, given the invasiveness of the procedure, percutaneous procedures are usually not preferred for smaller kidney stones (e.g., less than 1 cm).

[0015] Kidney stones can be treated using less invasive techniques including ureteroscopy. In ureteroscopy, the surgeon inserts an ureteroscope into the urethra, and traverses it through the bladder and into the ureter or kidney to provide direct visualization of the kidney stone. The surgeon then removes the kidney stone using a basket device if the kidney stone is small enough to pass through the urinary tract without difficulty. If the kidney stone is too large to pass through, the surgeon fractures the kidney stone into smaller pieces using a laser or other breaking device. A laser lithotripsy device is inserted through the ureteroscope and is used to fragmentize larger kidney stones into smaller pieces. After breaking the kidney stone into smaller pieces, the surgeon removes the laser or breaking device and inserts a basket or an extraction catheter to capture the kidney stone fragments under the direct visualization of the ureteroscope. Upon retrieving some of the kidney stone fragments, the surgeon removes the basket from the patient and empties the kidney stone fragments therefrom. This process is repeated until clinically significant kidney stones and kidney stone fragments are broken up and removed from the body.

[0016] It should be apparent that this process is extremely time consuming, costly, and inefficient because the surgeon is required to insert and remove the scope and basket into and out of the patient many times to completely remove the kidney stones and kidney stone fragments. Using a basket removal device to capture kidney stones or kidney stone fragments suffers from other drawbacks in

[0017] 2

[0018] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 that the basket is difficult to position adjacent the kidney stone fragments and maneuver in a manner that effectively retrieves the fragments. The training required for such a procedure is not insignificant and the basket removal technique can be difficult for even the most skilled surgeons. The extraction of the kidney stone or fragments can also be performed by suction, through a vacuum lumen of an extraction catheter. The distal end of the catheter is placed proximate to the stone or fragments, and suction is applied through a lumen.

[0019] Maneuvering the distal end of the catheter for reaching and removing the kidney stone is performed by a steering mechanism on the proximal, handle portion of the catheter. For ease of use, handle devices can have a steering lever that is easily operable by a surgeon with a use of his or her finger, typically a thumb. The rotation or pushing / pulling of the steering lever causes wires extending along a length of the catheter to bend or deflect the distal end of the catheter. Regardless of the ease in which these steering mechanisms can be used, surgeons are susceptible to hand fatigue due to the extended amount of time required to operate the kidney stone catheters. Thus, there is an unmet need for new steering mechanisms that cause less hand fatigue for surgeons and that are more easily operable.

[0020] SUMMARY

[0021] In accordance with one aspect of the inventions, a steering mechanism for a catheter assembly is provided. The steering mechanism includes a steering lever the operation of which manipulates a distal end of a catheter, and an overcenter assist mechanism operably engaged with the steering lever for assisting user movement of the steering lever. The overcenter assist mechanism can include a spring such that the spring has a greater stored energy when the steering lever is in a home position than when the steering lever is in operating positions away from the home position. The overcenter assist mechanism can be operably disengaged from the steering lever. The steering mechanism can additionally comprise a gear interface, wherein the steering lever rotationally operates the gear interface in a clockwise and counterclockwise direction. The

[0022] 3

[0023] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 overcenter assist mechanism can comprise a rotary pinion having gears operably engaged with the gear interface. The spring can be coupled at one end to the rotary pinion, such that the spring is configured to apply rotational force, via the rotary pinion, to the gear interface when the steering lever is moved off the home position. The steering mechanism can additionally comprise a rotary damper for decelerating the movement of the rotary pinion. The steering mechanism can additionally comprise a locking mechanism for locking the steering lever in place. The locking mechanism can include a lever cap from which the steering lever extends; a first disk fixedly interlocked with the lever cap, the first disk confining the degree at which the lever cap can rotate; and a second disk disposed between the lever cap and the first disk. The second disk can be configured to be engaged with the lever cap at a first position, such that in the first position the second disk can rotate in unison with the lever cap and the first disk, and disengaged from the lever cap to allow the second disk to rotate independently from the lever cap between the first position and a second position, and engaged with the lever cap at the second position, such that in the second position the steering lever becomes locked in place. The steering lever has a home position, where the distal end of the catheter is not manipulated, and operating positions where the distal end of the catheter is manipulated. In the home position the second disk is engaged to the lever cap at the first position to allow the lever cap, the first disk, and the second disk to rotate in unison to the operating positions. In at least one of the operating positions a user can engage the second disk to the lever cap at the second position by moving the second disk relative to the lever cap so as to lock the steering lever in place. The second disk can comprise a knob extending from an opening in the lever cap for allowing a user to rotate the second disk between the first and second positions. The lever cap can include a first indentation at the first position and a second indentation at the second position for engaging with a detent of the second disk. The steering mechanism can additionally include a wave spring or disk spring positioned between the first disk and the second disk. The wave spring or disk spring can engage the second disk against the lever cap to allow rotation in unison of the lever cap, the first

[0024] 4

[0025] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 disk, and the second disk. The wave spring or disk spring can allow the second disk to disengage from the lever cap so that the second disk can be rotated relative to the lever cap and the first disk between the first and second positions. The second disk can include a stop flange for abutting against a projection of a casing housing the second disk to prevent rotation of the lever cap, the first disk, and the second disk. The catheter can include at least two steering wires extending along a length of the catheter and in operating engagement with the steering lever, such that the movement of the steering lever manipulates the distal end of the catheter.

[0026] In accordance with another aspect of the inventions, a steering mechanism for a catheter assembly is provided. The steering mechanism comprising a steering lever the operation of which manipulates a distal end of a catheter, and a locking mechanism for locking the steering lever in place. The locking mechanism can comprise a lever cap from which the steering lever extends, a first disk fixedly interlocked with the lever cap, the first disk confining the degree at which the lever cap can rotate, and a second disk disposed between the lever cap and the first disk. The second disk can be configured to be engaged with the lever cap at a first position, such that in the first position the second disk can rotate in unison with the lever cap and the first disk, and disengaged from the lever cap to allow the second disk to rotate independently from the lever cap between the first position and a second position, and engaged with the lever cap at the second position, such that in the second position the steering lever becomes locked in place. The steering lever has a home position, where the distal end of the catheter is not manipulated, and operating positions where the distal end of the catheter is manipulated. In the home position the second disk is engaged to the lever cap at the first position to allow the lever cap, the first disk, and the second disk to rotate in unison to the operating positions. In at least one of the operating positions a user can engage the second disk to the lever cap at the second position by moving the second disk relative to the lever cap so as to lock the steering lever in place. The second disk can comprise a knob extending from an opening in the lever cap for allowing a user to rotate the

[0027] 5

[0028] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 second disk between the first and second positions. The lever cap can include a first indentation at the first position and a second indentation at the second position for engaging with a detent of the second disk. The steering mechanism can additionally include a wave spring or disk spring positioned between the first disk and the second disk. The wave spring or disk spring can engage the second disk against the lever cap to allow rotation in unison of the lever cap, the first disk, and the second disk. The wave spring or disk spring can allow the second disk to disengage from the lever cap so that the second disk can be rotated relative to the lever cap and the first disk between the first and second positions. The second disk can include a stop flange for abutting against a projection of a casing housing the second disk to prevent rotation of the lever cap, the first disk, and the second disk.

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Aspects of the present inventions will be described in detail with reference to the accompanying drawings:

[0031] Figure 1 is a partial schematic illustration of an embodiment of a steering mechanism from which a catheter extends.

[0032] Figure 2A is an embodiment of the steering mechanism with an overcenter assist mechanism.

[0033] Figure 2B is an exploded view of Figure 2A illustrating an embodiment of the components of the overcenter assist mechanism.

[0034] Figure 2C is a partial cross-section of Figure 2A illustrating an embodiment of the overcenter assist mechanism.

[0035] Figures 3, 4, 5, and 6 illustrate various exemplary components of an embodiment of the overcenter assist mechanism.

[0036] Figure 7A is an embodiment of the steering mechanism with an overcenter assist mechanism.

[0037] Figure 7B is an exploded view of Figure 7A illustrating an embodiment of the components of the overcenter assist mechanism.

[0038] 6

[0039] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051

[0040] Figures 8A and 8B illustrate two different positions of a steering lever and the overcenter assist mechanism according to an embodiment of the inventions.

[0041] Figure 9 is a graph illustrating the newtons of force (N) applied (vertical axis) versus degree of rotation of a steering lever (horizontal axis) without an overcenter assist mechanism versus a steering lever with an overcenter assist mechanism of an embodiment of the inventions.

[0042] Figure 10A is an embodiment of a steering mechanism with a lock mechanism.

[0043] Figure 10B is an embodiment of various exemplary components of the lock mechanism.

[0044] Figures 11 A, 11 B, and 11 C illustrate various exemplary components of an embodiment of the lock mechanism.

[0045] Figures 12A, 12B, 12C, and 12D illustrate the relationship between two disk components of one embodiment of the lock mechanism.

[0046] Figure 13 is a cutout perspective view of a casing of a handle used to manipulate a catheter illustrating the disk components of Figures 12A-12D when the lock mechanism is in a locked position.

[0047] Figures 14A, 14B, and 14C are front views of the steering and lock mechanisms in accordance with one embodiment of the inventions.

[0048] Figures 15A, 15B, and 15C are cutout rear views corresponding to Figures 14A, 14B, and 14C, respectively, showing the working mechanics of the lock mechanism in accordance with one embodiment of the inventions.

[0049] DESCRIPTION

[0050] Disclosed herein are steering systems and mechanisms to assist in navigation of insertable medical devices, such as endoscopes, minimally invasive treatment devices, and catheters. The catheter can be of any type and for any use, including catheters used for the guided removal of objects in vivo. The catheter can be configured to traverse compact and tortuous areas, such as the urinary tract, and used to fracture and remove debris, including kidney stones,

[0051] 7

[0052] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 such as by application of laser pulses and aspiration through a vacuum lumen of the catheter.

[0053] Figure 1 illustrates an embodiment of a treatment system 1 including a catheter assembly. In one preferred embodiment, the catheter assembly is a type used to treat kidney stones including, for example, to fragment and remove kidney stones. The system 1 includes a handle mechanism 12 from which a catheter portion 10 extends or to which the catheter 10 can be connected. The handle mechanism 12 allows the physician to hold and operate the catheter 10. The handle mechanism 12 can include features and mechanisms that allow a physician to operate and control various components and functions of the system, including, for example, a camera, a laser system, application of vacuum pressure, the amount of vacuum pressure, application of irrigation, the flow rate of irrigation, and the maneuverability of the catheter 10. For example, in the embodiments, the handle mechanism 12 can be configured to provide and control modes of operation, including irrigation and suction through irrigation and vacuum lumens of the catheter 10. The catheter 10 can include various ports and lumens, including a vacuum lumen and an irrigation lumen running along the length of the catheter 10. The system 1 can also include a camera (digital visualization and lighting, e.g., video chip and LED) positioned at an end, distal face, or a distal portion of the catheter 10 for providing real time imaging to the physician. The handle mechanism 12 can include mechanical and electronic controls that allow the physician to adjust the amount of negative pressure, regulate the discharge of the irrigation fluid, and steer the catheter through tortuous anatomical passageways via the use of components such as spools, wheels and / or levers attached to cables or pull wires. The system 1 can be coupled to a control unit. The control unit can be used to operate various functions of the system 1 . For example, the control unit can be used to operate the camera or the laser for fragmenting kidney stones.

[0054] The handle mechanism 12 includes a steering mechanism 14. The steering mechanism 14 is operable by a physician through manipulation (e.g., pushing / pulling or rotational movement) of a steering lever 16. The steering lever

[0055] 8

[0056] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051

[0057] 16 can operate any number of cables or pull wires, two of which are shown by way of example as cables 18 and 20. The steering lever 16 can effectively control the length and / or movement of the cables 18 and 20 that extend along a length of the catheter 10 and are anchored or secured to a distal end segment of the catheter 10. In one embodiment, the steering lever 16 can be operational plus / minus about 40 to 45 degrees. That is, the steering lever 16 can be pushed or rotated (about an axis) clockwise from its “home” or neutral position (where the distal end of the catheter 10 is not in a manipulated posture) to about 40 to 45 degrees to bend the distal end of the catheter 10. The steering lever 16 can be pulled or rotated counterclockwise about 40 to 45 degrees in the opposite direction starting from the “home” or neutral position to manipulate the distal end of the catheter 10 in a opposite direction. A rotation of about 40 to 45 degrees can be mechanically translated to the distal end of the catheter 10 bending or bowing approximately plus / minus 270 degrees. The degree of the movement of the steering lever 16, and in turn the degree to which the distal end segment of the catheter 10 can curve, can be designed to vary depending on the end use of the device. In one embodiment, the steering lever 16 can be operational plus / minus 25 degrees to plus / minus 65 degrees. The manipulation of the distal end of the catheter 10 allows the physician to appropriately guide the catheter 10 through tortuous anatomy and to place the distal end of the catheter 10 in line with a kidney stone during lasering and removal. The steering lever 16 is designed to be manipulated by a physician’s finger(s), preferably his or her thumb, thus making it easy for the physician to co-operate the remaining functional features incorporated into the handle mechanism 12 with his or her other fingers (e.g., a trigger mechanism for controlling vacuum (or suction), air flow, and / or irrigation).

[0058] Figures 2A, 2B, and 2C show a base or casing 22 for housing components including the steering mechanism 14. The casing 22 can be, for example, part of the handle mechanism 12. A gear interface 24, secured within the casing 22, is connected to the steering lever 16 and can be rotated clockwise and counterclockwise with the movement of the steering lever 16 (see Figures 8A

[0059] 9

[0060] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 and 8B for the connection of the lever 16 to the gear interface 24). A pair of spools 26 are disposed within cylindrical indentations 28 of the gear interface 24. A cable (e.g., cable 18 of Figure 1 ) can be connected to and wound around one of the spools 26 and another cable (e.g., cable 20 of Figure 1 ) can be connected to and wound around the other of the spools 26. The rotation of the spools 26 by the gear interface 24 causes one of the cables (e.g., cables 18 or 20) to be retracted, creating a tension, and the other cable (e.g., cables 18 or 20) to be released, creating a slack. The particular cable that is retracted and the one released depends on the direction of rotation of the gear interface 24. The retraction of the cable pulls the distal end of the catheter 10, causing the distal end of the catheter 10 to bend or bow toward the direction of the cable to which tension is applied. An end cap 30 secures the gear interface 24 and the spools 26 in the casing 22, while allowing the gear interface 24 and the spools 26 to properly rotate.

[0061] The steering mechanism 14 includes an overcenter assist mechanism 32. The overcenter mechanism 32 can be any mechanism that provides instability over its center position -- that is, at the steering lever’s 16 “home” or neutral position the overcenter mechanism 32 would have the maximum stored energy. As the steering lever 16 is moved off the “home” or neutral position, the overcenter mechanism 32 provides force assistance to the steering lever 16. Accordingly, when the overcenter mechanism 32 is at the center position, the steering lever 16 has the most resistance and it, with the gear interface 24, needs to move or rotate either clockwise or counterclockwise. In one embodiment, the components of the overcenter assist mechanism 32 can include, for example, a mechanism mount 34, a rotary damper 36, a rotary pinion 38 for rotationally interfacing with the gear interface 24, and an extension spring 40. A pin 42 can be inserted into a pin hole 38H (see figure 5) of the rotary pinion 38 for securing one end of the extension spring 40 to the rotary pinion 38. An end cap 44 secures the rotary damper 36 and the rotary pinion 38 against an upper face of the mechanism mount 34. End cap screws 44S can be used to screw the end cap 44 to the casing 22.

[0062] 10

[0063] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051

[0064] Figures 3, 4, 5, and 6 illustrate exemplary embodiments of the end cap 44, the rotary damper 36, the rotary pinion 38, and the mechanism mount 34. The end cap 44 includes eyelets 44E for receiving the end cap screws 44S for securing the end cap 44 to the casing 22. The underside of the end cap 44, facing the rotary damper 36, can have a space or cavity 44C that can have the same general shape as the rotary damper 36 for allowing the rotary damper 36 to fittingly sit within the cavity 44C of the end cap 44. A pair of bosses 44B extend out from the cavity 44C for connecting the end cap 44 to the rotary damper 36 by being inserted into eyelets 36E of the rotary damper 36. The end cap 44 can also include a notch or cut out segment 44N in which a part of the mechanism mount 34 can be inserted and secured. The rotary damper 36 can be any type of damping device that includes a mechanism for decelerating the movement of the rotary pinion 38 by damping the rotational movement through increased friction or resistance to rotation. The rotary damper 36 includes a cylindrical middle body portion 36B that houses the damping components. A set of extension wings 36W can extend from the middle body portion 41 and can include the eyelets 36E for receiving the pair of bosses 44B of the end cap 44. The rotary damper 36 can also include a non-cylindrical lug 36L for being inserted into a reciprocal opening 380 (e.g., non-cylindrical opening matching the shape of the lug 36L) of the rotary pinion 38 so as to allow the rotary damper 36 to operably engage with the rotary pinion 38 to dampen the movement of the rotary pinion 38. Gears 38G can extend around less than half of the perimeter of the rotary pinion 38 for operably engaging the gear interface 24. The number of gears 38G is relative to the degree to which the gear interface 24 is intended to be rotated by the steering lever 16. The pin hole 38H is configured to receive the pin 42 for securing an end of the spring 40 to the rotary pinion 38. The mechanism mount 34 includes a base 34B having a cutout 34C in which the rotary pinion 38 can sit and can be generally shaped in the same configuration as the rotary pinion 38. An arm or a beam 34A extends orthogonally out from the base 34B. A flange 34F extends outward from the arm 34A for insertion into the notch 44N of the end cap 44 for aligning of the mechanism mount 34 against the end cap 44. A groove 34G

[0065] 11

[0066] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 extends along an outer side of the arm 34A in which the spring 40 can sit. The spring 40, connected at one end to the rotary pinion 38, can extend through an opening 340 of the base 34B and be placed in and along the groove 34G to be secured at its opposing end to a crossbar or ledge 34L extending across the groove 34G. The orthogonal extension of the beam 34A relative to the base 34B not only allows efficient use of space in the handle 12 or casing 22, but also provides the possibility of including any number of spring 40 connection points along the groove 34G so that the force that the spring 40 applies to the rotary pinion 38 can be adjusted as desired.

[0067] Figures 7A and 7B illustrate another embodiment of the overcenter assist mechanism 32, which is generally similar to that of Figures 2A-2C, but for the end cap 44 being eliminated. The mounting mechanism 34 can function as an end cap, securing the rotary damper 36 and the rotary pinion 38 against the inner side of the casing 22.

[0068] Figure 8A and 8B illustrate the operation of the overcenter assist mechanism 32. The center position C can be seen in Figure 8B and not Figure 8A because the spring 40 is positioned over the center position C in Figure 8A. In Figure 8A, the steering lever 16 is in its home / neutral position and can, for example, be pushed up to 40 to 45 degrees clockwise or pulled in an opposite direction up to 40 to 45 degrees counterclockwise (as in Figure 8B). This clockwise and counterclockwise rotation applies tensions to the control cables (e.g., cables 18 and 20 of Figure 1 ), causing the distal end of the catheter 10 to be pulled by the cables. The spring 40 is coupled at one end to the rotary pinion 38 by the pin 42. The spring 40 is coupled on its opposite end 40E to the mechanism mount 34, or alternatively, it can be coupled to an internal connection member of the handle or casing 22. In the “home” or neutral position, the spring 40 extends through the center position C and is exerting a force by wanting to rotate the gear interface 24. The resistance against spring expansion or extension is at its highest when the spring 40 extends through the center position C. The counteracting forces between the gear interface 24 and rotary pinion 38 should be of a sufficient degree to prevent the overcenter assist mechanism 32

[0069] 12

[0070] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 from unintentionally moving the gear interface 24. The pitch (distance between each gear) and pressure angles (shape of the gears) should provide sufficient frictional force to prevent the rotary pinion 38 from moving the gear interface 24 without the assistance of the user.

[0071] Figure 8B illustrates the position of the components after the physician has applied pressure (e.g., with his or her thumb) on the steering lever 16 causing the rotary pinion 38 to move the gear interface 24. When the initial pressure is applied, release of the force of the spring 40, brought about through the extension of the spring 40, causes the overcenter assist mechanism 32 to provide force assistance to the steering lever 16. The extended spring 40 has a high degree of stored energy, thus a lesser amount of force by the physician is required to move the steering lever 16 beyond the center point position. The extension of the spring 40 applies rotational force to the gear interface 24, thereby pushing the steering lever 16 towards the same direction as the application of the initial pressure by the physician to the steering lever 16. Accordingly, the overcenter assist mechanism 32 assists the physician in operating the steering lever 16 to both its end limits, thereby alleviating thumb fatigue that the physician experiences in operating the device.

[0072] An overcenter assist mechanism 32 can be defined as having three pivot points where the distance between two sets of points if fixed while a distance between one of the sets will vary. Referring to Figure 8B, the three pivot points include point A, which is the connection point of the end of the spring 40 to the rotary pinion 38, point A’, which is the connection point of the other end of the spring 40 to the mechanism mount 34 (or casing 22), and point C, which is the center position. The distance between A-C and A’-C is fixed, while the spring distance, which is the distance between spring end points A-A’ will vary during operation.

[0073] In one embodiment, an “on / off” switch for overcenter assist mechanism 26 can be provided, thus giving the physician the option of using it. The switch can, for example, be a mechanism for engaging and disengaging the spring 34 from it connection point or the rotary pinion 38 from the gear interface 24.

[0074] 13

[0075] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051

[0076] The graph of Figure 9 is a comparison of the force necessary to move the steering lever 16 with the overcenter assist mechanism 32 (plot A) compared to the force necessary to move the steering lever 16 without the overcenter assist mechanism 32 (plot B). The vertical axis is the force. Two points have been marked as 8 Newtons and 12 Newtons only for illustrative purposes. The horizontal axis is the allowable degree of rotation of the steering lever 16 - from the “home” position (center vertical line) to the end positions on either side of the line, the end points of the plots equating to plus / minus 45 degrees. The overcenter assist mechanism 32 lowers the maximum user force required at full deflection compared to an unassisted device. The overcenter assist mechanism 32 also flattens the force profile through the full range of motion by slightly raising the forces near the neutral position and lowering both ends of the maximum defection forces. The steering mechanism 14 provides a balanced mechanical force so that the overall assistance never exceeds the force required to drive the catheter 10 in the desired direction. By keeping the force below this threshold, the physician gains full control of the catheter’s position with the benefit of a force reduction.

[0077] Figures 10A and 10B are another embodiment of the steering mechanism 14, which includes a positional locking mechanism 50. The locking mechanism 50 can be used alone or in combination of any of the embodiments of the overcenter assist mechanism 32. The steering mechanism 14 can include the steering lever 16 that extends out from a lever cap 52. The lever cap 52 can be attached over an opening 220 of the casing 22, through which the lever cap 52 can be fixedly interlocked with a limiting disk 54. The limiting disk 54 is configured to rotate clockwise and counterclockwise with the corresponding rotation of the lever cap 52, in response to the back-and-forth movement of the lever 16. A stop disk 56 is placed between the inner side of the casing 22 and the limiting disk 54. The stop disk 56 is configured to both rotate in unison with the lever cap 52 and the limiting ring 54, and to independently rotate relative to the lever cap 52 and the limiting disk 54 for locking the lever 16 in place. A wave spring or disk spring 58 is positioned between the limiting disk 54 and the stop

[0078] 14

[0079] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 disk 56 to allow the stop disk 56 to rotate in unison with and independently of the lever cap 52 and the limiting disk 54. The wave spring or disk spring 58 can include a circular or non-circular ring body having an uneven surface to provide, on one hand, the required bias to fixedly engage the stop disk 56 with the lever cap 22 so as to provide the unison rotational function and, on the other hand, the required compression to allow the stop disk 56 to be rotated by a physician relative to and independently from the lever cap 22 and the limiting disk 54. The lever cap 52 includes an opening 520 through which the stop disk 56 can be connected to an ergonomic cap 60. The back-and-forth actuation of the ergonomic cap 60 by a physician causes the stop disk 56 to disengage and fixedly reengage with the lever cap 52 between the lever cap’s 52 / lever’s 16 unlocked position and the lever cap’s 52 / lever’s 16 locked position. In essence, the stop disk 56 and disk spring 58 act like a clutch system and the ergonomic cap 60 as its gear stick, the operation of which switches the position of the stop disk 56 relative to the lever cap 52 and the limiting disk 54 for switching modes of operation between a neutral function (where the lever 16 can be freely actuated) and a locked function (where the lever 16 is locked in place).

[0080] Figures 11 A, 11 B, 11 C are perspective views of the limiting disk 54, the stop disk 56, and the lever cap 52. The limiting disk 54 can have a generally circular body 54B having a pair of opposing wing-shaped extensions 54W protruding from the rim of the circular body 54B. The wing-shaped extensions 54W are configured to abut against a pair of spaced apart projections 22P of the casing 22 (see figure 13) so as to confine the degree at which the limiting disk 54 can be rotated within the casing 22. The degree of rotation of the limiting disk 54 is correlated to the extent to which the steering lever 16 is designed to be actuated (or the chosen degree of bending of the distal end of the catheter 10). The circular body 54B fixedly interlocks against an inner side of the lever cap 52, with a set of the limiting disk’s 54 peripheral protrusions 54P (more clearly illustrated in Figures 12A-12D) being received by reciprocal peripheral grooves 52G on the inner side of the lever cap 52 so as to aid the limiting disk 54 from not rotating with respect to the lever cap 52. The limiting disk 54 can also include a

[0081] 15

[0082] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 central male extension 54E for coupling (e.g., by friction fit) to a female counterpart 52F of the lever cap 52 so as to provide a sturdier connection. The stop disk 56 includes a locking knob 56K that is configured to extend out from the lever cap’s 52 opening 520 to be coupled to the ergonomic cap 60. The stop disk 56 further includes a pair of detents 56D that are configured to be removable engaged with a first pair of indentations 521-1 , that can represent the lever cap’s 52 / lever’s 16 unlocked position, and a second pair of indentation 52I-2, that can represent the level cap’s 52 / lever’s 16 locked position. The actuation of the ergonomic cap 60 / locking knob 56K in a first rotational direction caused the detents 56D to disengage from the indentations 521-1 and snap-fit into indentations 52I-2. The driving of the ergonomic cap 60 / locking knob 56K in an opposing rotational direction causes the detents 56D to disengage from the indentations 52I-2 and snap-fit into indentations 521-1. Any practical number of indentations can be provided between indentations 521 -1 and 521-2 to provide the locking mechanism 50 with additional locking positions. The stop disk 56 further includes a stop flange 56F that is configured to extend out of an arc shaped opening 540 of the limiting disk 54. The stop flange 56F can translate, back-and-forth, along the arch shaped opening 540 and is confined within the opening 540. The actuation of the cap 60 / locking knob 56K for traversing the detents 56D between the first and second set of indentations 521-1 and 52I-2 translates to the rotational movement of the stop flange 56F from one end of the arc shaped opening 540 to an opposing end of the arc shaped opening 540. As will be explained below, the abutment of the stop flange 56F against the projection 22P of the casing 22 causes the lever 16 to lock in place.

[0083] Figures 12A, 12B, 12C, and 12D illustrate the kinematic relationship between limiting disk 54 and the stop disk 56. The stop disk 56 is rotatably disposed within a circular space of the limiting disk 54, with the stop flange 56F extending through the arc shaped opening 540. The movement of the stop disk 56 within respect to the limiting disk 54 is confined by the span of the arc shaped opening 540. The movement of the detents 56D between indentations 521-1 and 52I-2 of the lever cap 52 translates to the movement of the stop flange 56F along

[0084] 16

[0085] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 the span of the arc shaped opening 540, between the position shown in Figures 12A / 12C and the position in Figures 12B / 12D. When the detents 56D are engaged with indentations 521-1 , the stop flange 56F is at one end of the arc shaped opening 540 as shown in 12A / 12C, and the limiting disk 54 is not restricted from rotating between projections 22P (see Figures 15A and 15B). When the detents 56D are engaged with indentation 52I-2, the stop flange 56F is rotated to the opposing end of the arc shaped opening 540 as shown in Figures 12B / 12D, and the limiting disk 54 is restricted from rotating between projections 22P because the stop flange 56F is abutted against the projection 22P (see Figures 13 and 15C).

[0086] Referring to Figure 13, the limiting disk 54 and the stop disk 56 are shown positioned within the casing 22 in the locked position. Abutment of the stop flange 56F against the projection 22P prevents the limiting disk 54 and the lever cap 52 from rotating in the direction of the arrow. The positioning of the stop flange 56F at the opposing end of the arc shaped opening 540 allows the limiting disk 54 to freely rotate in the direction of the arrow and in between the projections 22P. The lever 16 is pressed down from its “home” or neutral position causing the distal tip of the catheter 10 to bend or curve. To hold the position of the catheter 10, the ergonomic cap 60 / locking knob 56K is pushed to force the detents 56D of the stop disk 56 to be released from the indentations 521-1 and snap-fit into indentations 52I-2 of the lever cap 52. Thus, the stop flange 56F is moved from one end arc shaped opening 540, wherein the limiting disk 54 is free to rotate between projections 22P, to the other end of the arc shaped opening 540, where the abutment of the stop flange 56F against the projection 22P prevents the limiting disk 54 from rotating. The lever 16 is locked in place until the ergonomic cap 60 / locking knob 56K is pressed to release the detents 56D of the stop disk 56 from indentations 52I-2 of the lever cap 52. Once the detents 56D are moved back to the indentations 521-1 , the limiting disk 54 has its full intended range of motion, which again is limited to the extent that the wingshaped extensions 54W can rotate between casing’s 22 projections 22P.

[0087] 17

[0088] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051

[0089] Figures 14A, 14B, 14C, 15A, 15B, and 15C best illustrate the operation of the locking mechanisms 50. Figure 15A is the rear view of Figure 14A with the lever 16 in the “home” or neutral position (e.g., the midway point between the terminal positions of the lever 16) and free to move up and down. In this position, the detents 56D of the stop disk 56 are engaged with indentations 52I-I of the lever cap 52 and the stop flange 56F is positioned at one end of the arc shaped opening 540 of the limiting disk 54, which permits the lever cap 52, the limiting disk 54, and the stop disk 56 to rotate clockwise and counterclockwise in unison in response to the user movement of the lever 16. The casing projections 22P confine the rotation of the limiting disk 54, thus affording the lever 16 a first terminal position at, for example, a plus 40 to 45 degree angle from the “home” or neutral position, and a second terminal position at a minus 40-45 degree angle from the “home” or neutral position. Figure 15B is the rear view of Figure 14B, illustrating the lever 16 in a down position (but not completely at the lever’s 16 terminal position as a space can be seen between the wing-shaped extensions 54W of the limiting disk 54 and the casing projection 22P). In the down position, the stop flange 56F of the stop disk 56 is positioned at one end of the arc shaped opening 540 and at a distance from the casing projection 22P, thus allowing unison rotation of the components. Figure 14C shows the ergonomic cap 60 (and locking knob 56K of the stop disk 56) pushed from an up position to a down position. The detents 56D of the stop disk 56 are disengaged from indentations 521-1 of the lever cap 52, and the stop disk 56 is rotated independently from the lever cap 52 and the limiting disk 56, until the detents 56D of the stop disk 56 snap-fit into indentations 52I-2 of the lever cap 52. The stop disk 56 again becomes fixedly connected to the lever cap 52 and is incapable of rotating independently from the lever cap 52 and the limiting disk 54. As shown in Figure 15C, in this position, the stop flange 56F of the stop disk 56 abuts against casing projection 22P, thus preventing any clockwise rotation (from the perspective of Figure 15C) of the lever cap 52, the limiting ring 54, and the stop disk 56, thus locking the lever 16 in place. It can be readily understood that switching the order of the indentations, where indentation 52I-2 is the “home” or neutral position and

[0090] 18

[0091] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 indentation 521-1 is the lever lock position can allow the lever 16 to be locked when in the up position. In this configuration, the ergonomic cap 60 / locking knob 56 are pushed upwards and not down as shown in Figure 14C.

[0092] When the detents 56D of the stop disk 56 engage indentations 521-1 and 52I-2 an audible “click” may be heard, notifying the physician that the steering lever 16 is in the home / neutral or locked position. The position of the ergonomic cap 60 can also be used as a visual indicator that the steering lever 16 is in the unlocked or locked position. In the locked position, the physician can hold, without any movement, the distal curvature of the catheter or, otherwise, the physician can rest should the physician be experiencing hand fatigue. In one embodiment, the steering mechanism 14 can have two pairs of detents / depressions, one pair being at the terminal rotational capability of the steering lever 16 - for example at the plus 40-45 degree mark and the minus 40- 45 degree mark. This allows the physician to lock the steering mechanism 14 at or about the maximum degree of contortion of the catheter’s distal end segment. In one embodiment, an additional pair of detent / depression can be positioned between the “home” or neutral position and the terminal rotational capability of the steering lever 16, for example at about the half-way mark of 22.5 degrees. This allows the physical to lock the lever 16 at about the half-way mark.

[0093] The singular forms “a,” “an,” and “the” are intended to include the plural forms and plural is intended to include singular, unless the context clearly indicates otherwise.

[0094] The terms “first, “second,” and the like are used simply to distinguish one feature or element from another feature or element and are not intended to define any order of the components, the type of components, or the function of the components. Thus, a first feature or element discussed herein could be termed a second feature or element, and similarly, a second feature or element discussed herein could be termed a first feature or element. For example, “a first disk” and “a second disk” does not connote any particular order of the positioning of the devices or type of devices, but is merely used to distinguish one device over another device. Moreover, when a claim refers to a “first element,” this

[0095] 19

[0096] 1102663313\1\AMERICAS Attorney Docket No. 125270.00051 should not be construed to imply or exclude the presence of a second element within the scope of the same claim.

[0097] The terms “about,” “approximately,” “substantially,” and “generally” are used to represent an amount, value, or degree, that is close to the stated amount, value, or degree, while still performing the same desired function or achieving the same result.

[0098] It is understood that this disclosure, in many respects, is only illustrative of the numerous alternative device embodiments of the present inventions. Changes may be made in the details, particularly in matters of arrangement of various components and addition of parts without exceeding the scope of the various embodiments of the inventions. Those skilled in the art will appreciate that the example embodiments and descriptions thereof are merely illustrative of the inventions as a whole. While several principles of the inventions are made clear in the example embodiments described above, those skilled in the art will appreciate that modifications of the structure, arrangement, elements, and uses may be within the scope of the practice of the inventions, and otherwise, which are particularly adapted to specific environments and operative requirements without departing from the scope of the inventions. In addition, while certain features and elements have been described in connection with particular embodiments, those skilled in the art will appreciate that those features and elements can be combined with the other embodiments disclosed herein.

[0099] 20

[0100] 1102663313\1\AMERICAS

Claims

Attorney Docket No. 125270.00051What is claimed is:1 . A steering mechanism for a catheter assembly, comprising: a steering lever the operation of which manipulates a distal end of a catheter; and an overcenter assist mechanism operably engaged with the steering lever for assisting user movement of the steering lever.

2. The steering mechanism of claim 1 , wherein the overcenter assist mechanism comprises a spring such that the spring has a greater stored energy when the steering lever is in a home position than when the steering lever is in operating positions away from the home position.

3. The steering mechanism of claims 1 and 2, wherein the overcenter assist mechanism can be operably disengaged from the steering lever.

4. The steering mechanism of claims 1 to 3, additionally comprising a gear interface, wherein the steering lever rotationally operates the gear interface in a clockwise and counterclockwise direction.

5. The steering mechanism of claim 4, wherein the overcenter assist mechanism comprises a rotary pinion having gears operably engaged with the gear interface and the spring is coupled at one end to the rotary pinion, such that the spring is configured to apply rotational force, via the rotary pinion, to the gear interface when the steering lever is moved off the home position.

6. The steering mechanism of claim 5, additionally comprising a rotary damper for decelerating the movement of the rotary pinion.211102663313\1\AMERICASAttorney Docket No. 125270.000517. The steering mechanism of claims 1 to 6, additionally comprising a locking mechanism for locking the steering lever in place.

8. The steering mechanism of claim to 7, wherein the locking mechanism comprises: a lever cap from which the steering lever extends; a first disk fixedly interlocked with the lever cap, the first disk confining the degree at which the lever cap can rotate; and a second disk disposed between the lever cap and the first disk, the second disk configured to be engaged with the lever cap at a first position, such that in the first position the second disk can rotate in unison with the lever cap and the first disk, and disengaged from the lever cap to allow the second disk to rotate independently from the lever cap between the first position and a second position; and engaged with the lever cap at the second position, such that in the second position the steering lever becomes locked in place.

9. The steering mechanism of claim 8, wherein the steering lever has a home position, where the distal end of the catheter is not manipulated, and operating positions where the distal end of the catheter is manipulated, such that in the home position the second disk is engaged to the lever cap at the first position to allow the lever cap, the first disk, and the second disk to rotate in unison to the operating positions, and in at least one of the operating positions a user can engage the second disk to the lever cap at the second position by moving the second disk relative to the lever cap so as to lock the steering lever in place.

10. The steering mechanism of claims 8 and 9, wherein the second disk comprises a knob extending from an opening in the lever cap for allowing a user to rotate the second disk between the first and second positions.221102663313\1\AMERICASAttorney Docket No. 125270.0005111 . The steering mechanism of claims 8 to 10, wherein the lever cap includes a first indentation at the first position and a second indentation at the second position for engaging with a detent of the second disk.

12. The steering mechanism of claims 8 to 11 , additionally including a wave spring or disk spring positioned between the first disk and the second disk, wherein the wave spring or disk spring engages the second disk against the lever cap to allow unison rotation of the lever cap, the first disk, and the second disk; and allows the second disk to disengage from the lever cap so that the second disk can be rotated relative to the lever cap and the first disk between the first and second positions.

13. The steering mechanism of claims 8 to 12, wherein the second disk includes a stop flange for abutting against a projection of a casing housing the second disk to prevent rotation of the lever cap, the first disk, and the second disk.

14. The steering mechanism of claims 1 to 13, wherein the catheter comprises at least two steering wires extending along a length of the catheter and in operating engagement with the steering lever, such that the movement of the steering lever manipulates the distal end of the catheter.

15. A steering mechanism for a catheter assembly, comprising: a steering lever the operation of which manipulates a distal end of a catheter; and a locking mechanism for locking the steering lever in place.

16. The steering mechanism of claim 15, wherein the locking mechanism comprises: a lever cap from which the steering lever extends;231102663313\1\AMERICASAttorney Docket No. 125270.00051 a first disk fixedly interlocked with the lever cap, the first disk confining the degree at which the lever cap can rotate; and a second disk disposed between the lever cap and the first disk, the second disk configured to be engaged with the lever cap at a first position, such that in the first position the second disk can rotate in unison with the lever cap and the first disk, and disengaged from the lever cap to allow the second disk to rotate independently from the lever cap between the first position and a second position; and engaged with the lever cap at the second position, such that in the second position the steering lever becomes locked in place.

17. The steering mechanism of claim 16, wherein the steering lever has a home position, where the distal end of the catheter is not manipulated, and operating positions where the distal end of the catheter is manipulated, such that in the home position the second disk is engaged to the lever cap at the first position to allow the lever cap, the first disk, and the second disk to rotate in unison to the operating positions, and in at least one of the operating positions a user can engage the second disk to the lever cap at the second position by moving the second disk relative to the lever cap so as to lock the steering lever in place.

18. The steering mechanism of claims 16 and 17, wherein the second disk comprises a knob extending from an opening in the lever cap for allowing a user to rotate the second disk between the first and second positions.

19. The steering mechanism of claims 16 to 18, wherein the lever cap includes a first indentation at the first position and a second indentation at the second position for engaging with a detent of the second disk.241102663313\1\AMERICASAttorney Docket No. 125270.0005120. The steering mechanism of claims 16 to 19, additionally including a wave spring or disk spring positioned between the first disk and the second disk, wherein the wave spring or disk spring engages the second disk against the lever cap to allow unison rotation of the lever cap, the first disk, and the second disk; and allows the second disk to disengage from the lever cap so that the second disk can be rotated relative to the lever cap and the first disk between the first and second positions.21 . The steering mechanism of claims 16 to 20, wherein the second disk includes a stop flange for abutting against a projection of a casing housing the second disk to prevent rotation of the lever cap, the first disk, and the second disk.251102663313\1\AMERICAS

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