Auto lock for catheter handle

The present invention is a catheter actuation handle for deflecting a distal end of a tubular catheter body, the handle including an auto-locking mechanism. The handle comprises upper and lower grip portions, an actuator, and an auto-locking mechanism. The auto-locking mechanism is adapted to hold a deflected distal end of the catheter in place without input from the operator. When the distal end of the catheter is deflected from its zero position, it typically will seek a return to its zero position, and as a result exerts a force on the actuator. The auto-locking mechanism acts by providing a second force that resists this force from the distal end and holds the distal end in place. As a result, the operator does not need to maintain contact with the buttons to maintain the distal end in a set position once placed there by actuating the actuator.

BACKGROUND OF THE INVENTION

a. Field of the Invention

The instant invention relates to catheters and sheaths and methods of using catheters and sheaths. In particular, the instant invention relates to steerable catheter or sheath control handles and methods of manufacturing and using such handles.

b. Background Art

Catheters that have flexible tubular bodies with deflectable distal ends and control handles for controlling distal end deflection are used for many noninvasive medical procedures. For example, catheters having conductive electrodes along the distal ends of their bodies are commonly used for intra-cardiac electrophysiology studies. The distal portion of such a catheter is typically placed into the heart to monitor and/or record the intra-cardiac electrical signals during electrophysiology studies or during intra-cardiac mapping. The orientation or configuration of the catheter distal end is controlled via an actuator located on a handle outside of the body, and the electrodes conduct cardiac electrical signals to appropriate monitoring and recording devices that are operatively connected at the handle of the catheter.

Typically, these catheters include a generally cylindrical electrically nonconductive body. The main body includes a flexible tube constructed from polyurethane, nylon or other electrically non-conductive flexible material. The main body further includes braided steel wires or other non-metallic fibers in its wall as reinforcing elements. Each electrode has a relatively fine electrically conductive wire attached thereto and extending through the main body of the catheter. The conductive wire extends from the distal end to a proximal end where electrical connectors such as plugs or jacks are provided to be plugged into a corresponding socket provided in a recording or monitoring device.

The distal portion of the main body is selectively deformed into a variety of curved configurations using the actuator. The actuator is commonly internally linked to the distal portion of the catheter by at least one actuation wire. Some catheters employ a single actuation wire, which is pulled (i.e., placed in tension) by the actuator in order to cause the distal portion of the main body to deform. Other catheters have at least two actuation wires, where the actuation of one wire (i.e., placing one wire in tension) results in the other wire going slack (i.e., the wire does not carry a compressive load). In such catheters, where the actuation wires are not adapted to carry compressive loads (i.e., the actuation wires are only meant to be placed in tension), the actuation wires are commonly called pull or tension wires.

To deform the distal end of the catheter into a variety of configurations, a more recent catheter design employs a pair of actuation wires that are adapted such that one of the actuation wires carries a compressive force when the other actuation wire carries a tensile force. In such catheters, where the actuation wires are adapted to carry both compressive and tension loads, the actuation wires are commonly called push/pull or tension/compression wires and the corresponding catheter actuators are called push-pull actuators. U.S. Pat. No. 5,861,024 to Rashidi, which issued Jan. 19, 1999, is representative of a push-pull actuator of this type, and the details thereof are incorporated herein by reference.

While many of the existing catheter actuators provide precise operation and good flexibility in movement of the distal portion of the body, the existing actuators often offer a range of distal portion displacement that is less than desirable. In other words, the amount of push/pull of the actuation wires (i.e., the steering travel) is often inadequate for the medical procedure being performed. The inadequacy of the steering travel typically results from the generally limited size of the actuator body, which is usually sized for receipt and manipulation between the thumb and index finger of a user's hand. Accordingly, a need exists to provide an improved actuating assembly for a catheter that increases the amount of steering travel associated with the actuator.

Similarly, once the distal portion has reached a desired position, the physician must either hold the catheter and the actuator in position to keep the distal portion in the desired position, or the handle of the catheter requires the physician to take a conscious step to maintain the distal portion of the catheter at the desired position. Accordingly, a need exists to provide an improved catheter and actuating assembly for a catheter that automatically holds the distal end of the catheter in the desired position. There is also a need in the art for a method of manufacturing and using such a catheter.

BRIEF SUMMARY OF THE INVENTION

The present invention is a catheter actuation handle for deflecting a distal end of a tubular catheter body, the handle including an auto-locking mechanism. The handle includes a grip portion, an actuator, and an auto-locking mechanism. The auto-locking mechanism is adapted to hold a deflected distal end of the catheter in place without input from the operator. As a result, the operator does not need to maintain contact with the buttons to maintain the distal end in a set position once placed there by actuating the actuator.

The auto-locking mechanism can include one or more washers, a bushing, a screw, and a base for receiving the screw. The one or more washers can be the same or different.

The bushing can be constructed of a polymer, a metal, stainless steel, or brass. The screw can be any type of screw, bolt, or connection means, including, preferably, a hex-head screw.

The auto-locking mechanism can further include a tensioning member. The tensioning member can be a Belleville washer or a spring.

The auto-locking mechanism can be a grip activated locking mechanism, or a friction wheel.

The vertical load path of the auto-locking mechanism can exclude the gripping portions or body of the catheter handle.

The present invention also includes a catheter system including a catheter with a catheter shaft with proximal and distal portions, a handle with an actuator and an auto-locking mechanism attached to the proximal portion of the catheter. The handle is adapted to hold the actuator in a position set by an operator. The catheter system can also include a second actuator and a second auto-locking mechanism.

The aspects, features, details, utilities, and advantages of the present invention will be apparent from reading the following description and claims, and from reviewing the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is an isometric view of the catheter10of the present invention. Throughout this specification, the term catheter is meant to include, without limitation, catheters, sheaths, and similar medical devices. As shown inFIG. 1, the catheter10can include an elongated flexible generally cylindrical hollow body12and an ergonomically shaped actuation handle14coupled to a proximal end16of the body12. The actuation handle14is adapted to control the deflection of a deflectable distal end18of the body12.

In one embodiment, as taught in U.S. patent application Ser. No. 11/170,550 to Dudney et al., which was filed on Jun. 28, 2005 and is hereby incorporated in its entirety into this application, the catheter10is advantageous for several reasons. First, the actuation handle14has a novel rack and pinion actuation mechanism that provides significantly increased steering travel of the distal end18of the body12, as compared to prior art actuation handles. Second, the actuation mechanism is configured such that it does not compress the actuation wires. Third, the actuation mechanism is configured such that the actuation force perceived by a user is minimized and generally constant over the full range of displacement, as compared to prior art actuation mechanisms. Fourth, when the body12includes three actuation wires extending through the body12from the distal end18to the actuation handle14, the handle has a second actuation mechanism that is configured to actuate the third actuation wire.

As shown inFIG. 1, the actuation handle14can include a first actuator20, upper and lower buttons22a,22bof a second actuator, upper and lower grip portions24a,24b, an electrical plug26at the proximal end of the handle14, and a strain relief28at the distal end of the handle14. The upper and lower grip portions24a,24bdefine a space29that extends laterally through the grip portions24a,24b. The first actuator20is pivotally coupled to the grip portions24a,24band resides in the space29. The first actuator20may pivotally displace laterally relative to the grip portions24a,24bthrough the space29. Such pivotal displacement of the first actuator20allows a user to bi-directionally deflect the distal end18of the body12.

The upper and lower buttons22a,22bof the second actuator22are slideably coupled to their respective grip portions24a,24bin such a manner that they may slideably displace along their respective grip portions24a,24bin a direction that is generally parallel to the longitudinal axis of the handle14. Such slideable displacement of the buttons22a,22bof the second actuator22allows a user to deflect the distal end18of the body12in a third direction. For example, as indicated inFIG. 1, in one embodiment where the distal end18forms a loop or lariat, the first actuator20causes the distal end18to deflect bi-directionally right or left, and the buttons22a,22bof the second actuator22cause the distal end18to increase or decrease the diameter of its loop or lariat. In another embodiment, as taught in U.S. patent application Ser. No. 10/784,511 to Rashidi, which was filed on Feb. 23, 2004 and is incorporated by reference in its entirety into this application, the first actuator20causes the distal end18to bi-directionally loop and to increase or decrease the extent to which the distal end18loops. The buttons22a,22bof the second actuator22cause the loop or lariat formed by the distal end18to nod or deflect.

As illustrated inFIG. 1, the distal end18of the body12can include a plurality of spaced electrodes30. Each electrode30is connected to a fine electrical conductor wire that extends to the electrical plug26through the body12, the strain relief28, and the handle14. The electrical plug26is adapted to be connected to a device, such as a recording, monitoring, or RF ablation device. While a variety of material can be used to construct body12, it is typically constructed of polyurethane, nylon or any suitable electrically non-conductive material. The body12serves as at least a portion of the blood contacting segment of the catheter10and is vascularly inserted into a patient by methods and means well known in the art.

The actuation wires can be any of the actuation wire types known in the art. They can be pull or tension wires (i.e., the actuation wires are not adapted to support a compressive load). They can also be configured such that the actuation wires are pull/push or tension/compression wires (is., the actuation wires are adapted to support a compressive load). Thus, in the context of the first and second actuation wires, when one actuation wire is placed in tension, the other actuation wire will carry a compressive load. The actuation wires can be formed from a super elastic Nitinol wire or another suitable material. Detailed discussion regarding the configuration of the body12and its three actuation wires is provided in the aforementioned incorporated U.S. patent and patent application.

For a detailed discussion of one embodiment of the handle14of the subject invention, reference is now made toFIG. 2, which is an isometric view of the handle14with the upper and lower grip portions24a,24bseparated and the first actuation mechanism40exploded to better illustrate its various components. As shown inFIG. 2, the grip portions24a,24bof the handle14are adapted to matingly couple with each other and serve as an enclosure and mounting base for the first and second actuation mechanisms40,42and the auto-locking mechanism,54. The first actuation mechanism40is mounted in a distal portion of the handle14, and the second actuation mechanism42is mounted in a proximal portion of the handle14. The electrical plug26is mounted in a proximal end assembly46that serves as the proximal end of the handle14.

As illustrated inFIG. 2, the first actuation mechanism40includes the first actuator20, a gear assembly48with a cover50, first and second control arms52a,52b, and an auto-locking mechanism54. The auto-locking mechanism54can assume any one of numerous formats, but is adapted to hold the distal end of the catheter in place without conscious and/or actual input from the operator, depending on the embodiment.

In catheter operation, the operator will manipulate one or more of the first or second actuators20,22, causing the distal end18to deflect from the original position as manufactured, or its zero position. Typically, the distal end18of the catheter is naturally biased to return toward its zero position, and accordingly exerts a pressure on the first or second actuators20,22through the actuation wires to return towards the zero position. In prior art devices this pressure must be counteracted by the operator, either by holding the actuator(s) in place, or by manually setting a locking mechanism before or during the procedure. In the present invention, the auto-locking mechanism automatically retains the distal end in the deflected state set by the operator with no input from the operator, freeing the operator to perform other tasks.

As illustrated inFIG. 2, the auto-locking mechanism54pivotally couples the first actuator20to the lower grip portion24band can include one or more washers56, a bushing58and a screw60, e.g., a hex-head screw, for attaching the auto-locking mechanism54as an integral unit to a pivot base62on the lower grip portion24b. As shown inFIG. 2, each washer56can be a different size.

For a detailed discussion of the gear assembly48, reference is now made toFIG. 3, which is an exploded isometric view of the gear assembly48. As shown inFIG. 3, the gear assembly48includes a frame64, first and second pinion gears66a,66b, first and second wire blocks68a,68b, and the cover50. The frame64includes a face plate70, a base or floor71, and first and second stationary gear racks72a,72b. The first and second stationary gear racks72a,72bare fixed to the lateral sides of the base71of the frame64and oriented such that their respective teeth sides74a,74bface each other and are generally parallel to the longitudinal centerline of the frame64. The face plate70is aligned with the longitudinal centerline of the frame64, positioned between the two stationary gear racks72a,72b, and generally perpendicular to the base71of the frame64. Each vertical side or face75a,75bof the faceplate70is generally planar.

As indicated inFIG. 3, each wire block68a,68bincludes a movable gear rack76a,76b, a generally planar vertically oriented face77a,77b, and a hole78a,78b. Each movable gear rack76a,76bextends downwardly from its respective wire block68a,68band has teeth80a,80bon one side and a generally planar vertical face77a,77bon the other. The moveable gear racks76a,76bare oriented such that they are generally parallel to each other, their teeth80a,80bface away from each other, and their planar faces77a,77bface each other in a generally parallel arrangement.

Each hole78a,78bis adapted to receive a proximal end of one of the first and second actuation wires. For example, as illustrated inFIG. 4, which is a top plan view of a first embodiment of the first actuation mechanism40mounted in the proximal portion of the lower grip portion24b, the first and second actuation wires81a,81bare received in their respective holes78a,78bupon exiting the proximal end16of the body12.

As shown inFIG. 4, the actuator20is pivotally mounted to the lower grip portion24bvia the pivot assembly54. The first actuation assembly40is located distal to the actuator20and proximal to the to the strain relief28. In one embodiment, the first actuator20includes a position indicator point82on its most distal edge and first and second openings84a,84bthat are located on opposite lateral sides of the actuator20.

As indicated inFIG. 4, a proximal end of a control arm52a,52bresides in each opening84a,84b. In a first embodiment of the first actuation mechanism48, as depicted inFIG. 4, the openings84a,84bare arcuate slots84a,84bthat are substantially longer in length than the diameter of the control arm52a,52b.

As illustrated inFIG. 5, which is an enlarged plan view of the gear assembly48with the top portions of the wire blocks68a,68bremoved to better illustrate the gearing arrangement, a distal end of a control arm52a,52bresides in a hole86a,86bin each pinion gear66a,66b. In one embodiment, each hole86a,86bis positioned at the axial center of its respective pinion gear66a,66b. In another embodiment, as depicted inFIG. 5, each hole86a,86bis offset from the axial center of its respective pinion gear66a,66b.

As shown inFIG. 6, which is a bottom plan view of the handle14with the lower grip portion24bremoved to reveal portions of the first and second actuation mechanisms40,42, each control arm52a,52bextends between its respective points of connection with a hole86a,86bof a pinion66a,66band an opening84a,84bin the first actuator20. Thus, as will be understood fromFIGS. 4-6, the control arms52a,52bserve as linkages to transmit the motion of the first actuator20to the pinions66a,66b.

As illustrated inFIG. 5, each pinion gear66a,66bis positioned between, and engaged with, a stationary gear rack72a,72band a moveable gear rack76a,76b. A generally planar back77a,77bof each moveable gear rack76a,76bslideably abuts against a respective generally planar face75a,75bof the faceplate70.

As shown inFIG. 5, in one embodiment, where the hole86a,86bin each pinion66a,66bis offset from the pinion's axial center, when the pinion66a,66bis positioned at the most distal end of the stationary gear rack72,72b, the hole86a,86bwill be located immediately adjacent, and slightly distal to, the most distal tooth88a,88bof the respective stationary gear rack72a,72b. In one embodiment, to prevent the pinions66a,66bfrom over traveling relative to the gear racks72a,72b,76a,76b, a blank toothless section90a,90bexists along the circumference of each pinion66a,66bnext to the pinion's hole86a,86b.

As shown inFIGS. 5 and 6, an arcuate slot92a,92bexists between each pair of gear racks72a,72b,76a,76bin a base or floor portion71of the frame64. Each arcuate slot92a,92bserves as a pathway through which the distal portion of each control arm52a,52bmay pass as the respective pinion gear66a,66bdisplaces along the stationary gear rack72a,72b. The arcuate configuration of the arcuate slots92a,92ballows the distal parts of each control arm52a,52bto follow the sinusoidal displacement of the holes86a,86bwhen the pinions66a,66bdisplace along the stationary gear racks72a,72b.

Because the holes86a,86bare offset from the axial centers of the pinions66a,66b, a mechanical advantage is created as compared to a configuration where the holes86a,86bare centered at the axial centers of the pinions66a,66b. The mechanical advantage results in an actuation force, as perceived by a user, that is less than and more constant than the actuation forces required to operate prior art catheters.

The operation of the first embodiment of the first actuation mechanism40, wherein the each opening84a,84bis an arcuate slot84a,84b, will now be described while referencingFIGS. 4-6. As indicated inFIGS. 4-6, when the first actuation mechanism40is in a neutral pivotal position (i.e., when the wire blocks68a,68bare both in their most proximal positions and the position indicator point82is facing distally and is generally aligned with the longitudinal centerline of the lower grip portion24b, as depicted inFIG. 4), the proximal end of each control arm52a,52bis in the most distal portion of its respective arcuate slot84a,84b. This configuration of the first embodiment of the first actuation mechanism40is advantageous where the actuation wires81a,81bare tension or pull type actuation wires. More specifically, it is advantageous where the actuation wires81a,81bare only to be placed in tension and never to be compressed, thereby avoiding buckling of the actuation wires81a,81b.

For example, as can be understood fromFIGS. 4-6, when the first actuator20is pivoted in a first direction (e.g., counterclockwiseFIG. 4), the proximal end of the first control arm52ais engaged by the distal end of the first arcuate slot84aand the first control arm52ais pulled proximally. This causes the distal end of the first control arm52ato cause the first pinion gear66ato displace proximally along the corresponding stationary gear rack72a. The rotation of the first pinion gear66acauses the corresponding moveable gear rack76ato be driven proximally. As can be understood fromFIG. 4, this causes the corresponding wire block68ato place the first actuation wire81ain tension as the wire block68aproximally displaces.

While pivoting the actuator20in the first direction causes the first wire block68ato act on the first actuation wire81a, such a movement, generally speaking, has no impact on the second wire block68bor the second actuation wire81b. This is because a counter clockwise rotation of the actuator20simply causes the second arcuate slot84bto slide along the proximal end of the control arm52bwithout the proximal end of the second arcuate slot84bencountering the proximal end of the control arm52b. As a result, the first actuator20does not distally drive the second control arm52band the second wire block68bis not caused to distally displace. Accordingly, the second actuation wire81bis not placed in tension or compression when the actuator20is pivoted in the first direction (i.e., counterclockwise). In other words, the second actuation wire81bis allowed to relax and move freely.

In one embodiment, when the actuator20is pivoted back to the neutral pivotal position depicted inFIG. 4, the proximal end of the first arcuate slot84adoes not encounter the proximal end of the first control arm52a. As a result, the first actuator20does not drive the first wire block68aand its corresponding actuation wire52adistally back into the neutral position. Instead, the tension that the deflected distal end18exerts on the first actuation wire52acauses the wire52aand its corresponding block52ato return to the neutral position.

Continuing the example, as can be understood fromFIGS. 4-6, when the first actuator20is pivoted in a second direction (is., clockwise inFIG. 4), the proximal end of the second control arm52bis engaged by the distal end of the second arcuate slot84band the second control arm52bis pulled proximally. This causes the distal end of the second control arm52bto cause the second pinion gear66bto displace proximally along the corresponding stationary gear rack72b. The rotation of the second pinion gear66bcauses the corresponding moveable gear rack76bto be driven proximally. As can be understood fromFIG. 4, this causes the corresponding wire block68bto place the second actuation wire81bin tension as the wire block68bproximally displaces.

While pivoting the actuator20in the second direction causes the second wire block68bto act on the second actuation wire81b, such a movement, generally speaking, has no impact on the first wire block68aor the first actuation wire81a. This is because a clockwise rotation of the actuator20simply causes the first arcuate slot84ato slide along the proximal end of the control arm52awithout the proximal end of the first arcuate slot84aencountering the proximal end of the control arm52a. As a result, the first actuator20does not distally drive the first control arm52aand the first wire block68ais not caused to distally displace. Accordingly, the first actuation wire81ais not placed in tension or compression when the actuator20is pivoted in the second direction (i.e., clockwise). In other words, the first actuation wire81ais allowed to relax and move freely.

In one embodiment, when the actuator20is pivoted back to the neutral pivotal position depicted inFIG. 4, the proximal end of the second arcuate slot84bdoes not encounter the proximal end of the second control arm52b. As a result, the first actuator20does not drive the second wire block68band its corresponding actuation wire52bdistally back into the neutral position. Instead, the tension that the deflected distal end18exerts on the second actuation wire52bcauses the wire52band its corresponding block52bto return to the neutral position.

As can be understood fromFIGS. 4 and 5, because of the gearing arrangement, the proximal linear displacement of a moveable gear rack76a,76band, as a result, its corresponding actuation wire81a,81bis generally twice the proximal linear displacement of the corresponding pinion gear66a,66b. This is because the proximal displacement of a moveable gear rack76,76bis the sum of a pinion gear's linear proximal displacement along a stationary gear rack72a,72bplus the pinion gear's rotational displacement.

For a discussion of a second embodiment of the first actuation mechanism40, reference is now made toFIGS. 7-9.FIGS. 7-9are, respectively, the same views depicted inFIGS. 4-6, except of the second embodiment of the first actuation mechanism40. Generally speaking, the features of the first and second embodiments of the first actuation mechanism40are the same, except as provided in the following discussion.

As shown inFIG. 7, unlike the arcuate slots84a,84bof the first embodiment of the actuation mechanism40(as discussed in reference toFIGS. 4-6), the openings84a,84bof the second embodiment are circular holes84a,84bwith diameters generally equal to the diameter of the control arms52a,52b. As indicated inFIG. 7, a proximal end of a control arm52a,52bresides in each circular opening84a,84b.

As can be understood fromFIGS. 7-9, in the second embodiment of the actuation mechanism40, when the first actuation mechanism40is in a neutral pivotal position (i.e., the position indicator point82is facing distally and generally aligned with the longitudinal centerline of the lower grip portion24b, as depicted inFIG. 7), each pinion66a,66bis positioned approximately midway along both of the lengths of its respective stationary gear rack72a,72band moveable gear rack76a,76b. This arrangement allows the control arms52a,52bto oppositely and equally move relative to each other when the actuator20is pivoted. This movement is brought about in the second embodiment of the first actuation mechanism40because, unlike the arcuate slots84a,84bof the first embodiment, the circular openings84a,84bof the second embodiment prevent displacement between the proximal ends of the control arms52a,52band the actuator20. The configuration of the second embodiment of the first actuation mechanism40is advantageous where the actuation wires81a,81bare pull/push or tension/compression type actuation wires.

For example, as can be understood fromFIGS. 7-9, when the first actuator20is pivoted in a first direction (e.g., counterclockwise inFIG. 7), the proximal end of the first control arm52ais pulled proximally by the first circular opening84a, and the proximal end of the second control arm52bis pushed distally by the second circular opening84b. Accordingly, the distal end of the first control arm52apulls the first pinion gear66aproximally along its corresponding stationary gear rack72a, and the distal end of the second control arm52bpushes the second pinion gear66bdistally along its corresponding stationary gear rack72b. The rotation of the first pinion gear66aproximally drives its corresponding moveable gear rack76a, and the rotation of the second pinion gear66bdistally drives its corresponding moveable gear rack76b. As can be understood fromFIG. 7, this causes the first wire block68ato place the first actuation wire81ain tension as the wire block68aproximally displaces. Also, this causes the second wire block68bto push (i.e., compress) the second actuation wire81bdistally as the second wire block68bdistally displaces.

As can be understood fromFIGS. 7-9, pivoting the first actuator20in a second direction (i.e., clockwise) reverses the movement of the control arms52a,52b. Accordingly, the second wire block68bmoves proximally (i.e., the second actuation wire81bis placed into tension), and first wire block68amoves distally (i.e., the first actuation wire81ais compressed or released).

For a detailed discussion of one embodiment of the second actuation mechanism42, reference is now made toFIG. 10, which is an isometric view of the handle14with the upper and lower grip portions24a,24bseparated and the second actuation mechanism42exploded to better illustrate its various components. As shown inFIG. 10, the second actuation mechanism42is mounted in a proximal portion of the handle14and includes a second actuator100with upper and lower arms102a,102b, the upper and lower buttons22a,22bof the second actuator100, a pivot assembly104, upper and lower pins106a,106b, a lever108, and a slide block110.

As illustrated inFIG. 10, the actuation handle14can include a second actuation mechanism22with upper and lower buttons22a,22b. The second actuation mechanism includes a second actuator100that is generally U-shaped. The second actuator's arms102a,102bare generally vertically aligned and offset from each other in a parallel arrangement to form a gap103through which the proximal portion of the first actuator20displaces. The lower arm102bslideably resides in a longitudinal slot or groove113in the lower grip portion24b. Similarly, the upper arm102aslideably resides in a longitudinal slot or groove in the upper grip portion24a.

As shown inFIG. 10, each arm102a,102bincludes a head112a,112bwith a pinhole114a,114bfor receiving a pin106a,106b. The upper head112aextends through a longitudinal slot115in the upper grip portion24ato couple to the upper button22a. Similarly, the lower head112bextends through a longitudinal slot in the lower grip portion24bto couple to the lower button22b. The lower head112bresides in a seat117in the lower button22band is coupled thereto via the pin106b. Likewise, the upper head112aresides in a seat in the upper button22aand is coupled thereto via the pin106a. Because each button22a,22bis coupled to an arm102a,102bof the second actuator100, the buttons22a,22bare slaved together.

As indicated inFIG. 10, the heads112a,112bare slideably displaceable within their respective longitudinal slots115. Thus, when a user slides the buttons22a,22blongitudinally relative to the grip portions24a,24bto actuate the second actuation assembly42, the arms102a,102band heads112a,112bslideably displace in their respective slots113,115.

As shown inFIG. 10, the lever108is pivotally coupled to a pivot base118in the lower grip portion24bvia the pivot assembly104. The pivot assembly104includes a series of washers120(including a Belleville spring washer to compensate for compression set or material creep during the catheter's shelf life), and a hex-head screw124for securing the pivot assembly104to the pivot base118as one integral unit. When the hex-head screw124is properly tightened, the pivot assembly104is configured such that it acts as an auto-locking mechanism54by providing a tension drag feature that holds the lever108in place although the user has released the buttons22a,22b. As a result, the user does not need to maintain contact with the buttons22a,22bto maintain the distal end18in a set position once placed there by the user actuating the second actuation mechanism42.

As illustrated inFIG. 10, in one embodiment, the lever108is generally semicircular such that it has a generally linear edge119and a generally arcuate edge121extending between the first and second ends of the linear edge119. The linear edge119is adjacent the pivot assembly104and faces generally distally. In one embodiment, the radius of the arcuate edge121is generally equal to the distance between the arcuate edge121and the axis of the pivot assembly104. The arcuate edge121faces generally proximally.

For further discussion of the components of the second actuation mechanism42, reference is now made toFIG. 11, which is a top plan view of the second actuation mechanism42mounted in the lower grip portion24bwith the upper grip portion24aremoved. As indicated inFIG. 11, a bottom end of the slide block110is slideably received in a lower groove or slot128in the lower grip portion24b. Similarly, a top end of the slide block110is slideably received in an upper groove or slot in the upper grip portion24a. The slots128are generally parallel to the longitudinal axis of the handle14.

As illustrated inFIG. 11, a third actuation wire129extends from the distal end18of the body12and into the handle14to couple the slide block110. In one embodiment, the third actuation wire129also serves as an electrical wire leading from one or more electrodes30in the distal tip18to the electrical plug26in the proximal end of the handle14. In doing so, the third actuation wire129passes through, and couples to, the slide block110.

As shown inFIG. 11, a threaded rod130extends between a proximal side of the slide block110and a clevis132pivotally attached to a first end of the lever108via a pin109. The threads on the threaded rod130allow the distance between the clevis132and the slide block110to be adjusted. Thus, the initial actuation wire position relative to the lever108can be adjusted via the threaded rod130.

As indicated inFIG. 11, an arm134extends from the proximal end of the second actuator100in a direction opposite from the slide block110. A link136is pivotally coupled to an end of the arm134via a pin138. A cable140is coupled to the link136and extends to and around the arcuate side121of the lever108to couple to the lever108via an attachment feature142(e.g., a screw, bolt, pin, etc.). The arcuate side121of the lever108is grooved or slotted to receive the cable140. The cable140and arcuate side121of the lever108operate together like a belt and pulley such that a moment arm between the cable140and the pivotable lever108remains constant as the lever108pivots.

As can be understood fromFIG. 11, when actuating the third actuation wire129to cause the distal end18of the body12to deflect, a user displaces a button22a,22bdistally, which causes the U-shaped second actuator100to displace distally. As a result, the arm134pulls the cable140distally, thereby causing the lever108to pivot in a counterclockwise direction about the pivot assembly104. This pivoting movement causes the clevis132to pull the slide block110in a proximal direction. The proximal movement of the slide block110places the third actuation wire129into tension (i.e., it pulls the third actuation wire129), which causes the distal end18of the body12to deflect.

Increasingly deflecting the distal end of the body12requires an increasing force. Thus, during the initial stages of distal end deflection of the body12, the force needed to pull the third actuation wire129is lower than at the final stages of distal end deflection. The increasing force needed to further increase the deflection of the distal end of the body12is addressed by the configuration between the clevis132and the lever108. Specifically, the configuration between the clevis132and the lever108is such that the moment arm changes as the lever108pivots.

The moment arm length between the clevis132and the pivot assembly104of the lever108is greatest during the initial stages of distal tip deflection (i.e., when the pin109is at its most distal position). Because of the configuration between the clevis132and the lever108, the length of the moment arm decreases as the distal end18is increasingly deflected (i.e., the pin109moves proximally). Consequently, the mechanical advantage at the buttons22a,22bis the least when the actuation wire tension is low (i.e., during the initial stages of distal end deflection) and the most when the actuation wire tension is high (i.e., during the last stages of distal end deflection approaching full deflection).

As can be understood fromFIG. 11, to allow the deflected distal end18to return to its non-deflected configuration, a user proximally displaces a button22a,22b, which causes the U-shaped second actuator100to proximally displace. This provides slack in the cable140, which allows the lever108to pivot clockwise as the spring force stored in the deflected distal end18acts to distally pull the third actuation wire129and, as a result, the slide block10as the distal end18springs back into a non-deflected configuration.

In use, the body12of the catheter10is inserted into the patient in a manner well known in the art. An operator grasps the handle14and manipulates the first actuator20between his thumb and finger. Advantageously, the first actuator20protrudes from each side of the handle14to allow for such ease of movement and manipulation. The first actuator20is moved relative to the handle14, which causes the first and second actuation wires78a,78bto be displaced via the first actuation mechanism40. As a result, the distal end18of the body12deflects.

To deflect the distal end18of the body12in another manner, the user distally slides the buttons22a,22bwith a thumb or finger. This causes the third action wire129to displace via the second actuation mechanism42. As a result, the distal end18of the body12deflects in manner different from the deflection brought about by the actuation of the first actuation mechanism40. For example, the displacement of the third action wire129may bring about a deflection of the distal end into any curvilinear shape, such as a loop, a spiral, or into an s shape. In addition, the distal end may be preformed into any curvilinear shape, including a loop, a spiral, or an s-shape, and the displacement of the third action wire may bring about a widening or narrowing of the curvilinear shape. Likewise, the first and second action wires78a,78bcan bring about a deflection in a first plane, and the third action wire129may bring about a deflection in a second plane, e.g., a plane perpendicular to the first plane.

In another embodiment, as illustrated inFIG. 2, an auto-locking mechanism54pivotally couples the first actuator20to the lower grip portion24band can include one or more washers56, a bushing58and a screw60, e.g., a hex-head screw, for attaching the auto-locking mechanism54as an integral unit to a pivot base62on the lower grip portion24b. As shown inFIG. 2, each washer56can be the same or different.

As will be appreciated by one of ordinary skill in the art, the bushing58can be constructed of any of a number of materials, including commonly available polymers, e.g., PEEK, polysulfone, etc., metals, e.g., stainless steel, brass, etc., or other materials. The washers56can be any commonly available form, including flat washers or wave washers and constructed of stainless steel, brass, or a polymeric material. The screw60can be any type of screw, bolt, or connection means, including, preferably, a hex-head screw. The pivot base62can be constructed of the same or different materials as the lower grip portion24b. The pivot base62can be constructed integrally with the lower grip portion24b, or it can be a separate piece that is glued, welded or otherwise attached to lower grip portion24b.

As shown inFIGS. 2,12and12A, in operation a washer56is optionally placed on the landing62a. The actuator20is then placed over the pivot base62and onto the washer56or the landing62a. An optional washer56can be placed on the actuator20. The bushing58is threaded through the washers56, actuator20, and pivot base62. A hex-head screw60is then threaded through the bushing58, the washers56, the actuator20, and is tightened into the pivot base62. It is preferable that the bushing58fit closely over the pivot base62so as to prevent excessive lateral motion between the bushing58and the pivot base62during rotational motion of the actuator20. Likewise, it is preferable that the actuator20fit closely over the bushing58to prevent lateral motion between the bushing58and the actuator20during rotational motion of the actuator20.

The screw60will be tightened during manufacturing to create a tension T. T is determined by considering several factors, and will vary from application to application, but must be a sufficient tension to counteract the distal end's bias towards its zero position. At the same time, if T is too large the operator will be forced to exert great pressure to actuate the catheter, which is undesirable. Typical commercially available catheters today require 2-10 pounds of thumb force from the operator on the actuation handle to deflect the distal end in a desired direction. For example, a catheter may require 3 pounds of thumb force. In such a case, depending on the catheter construction, the deflected distal end18may exert 2-3 pounds of force towards its neutral or zero position. Accordingly, the tension T is set sufficiently large to counteract that force, e.g., 3 or more pounds. The tension T can also be increased as necessary to give the catheter operation a desirable level of thumb force for the operator, as increasing the tension T will increase the thumb force required to operate the catheter. Once the screw60has been tightened to create the desired tension T, the screw60can be permanently or semi-permanently fixed in place by application of a locking fluid.

The bushing58can have notches58acut in its bottom portion that are designed to mate with slats62b. The slats62bare located in the space between the pivot point62and the landing62a. When the notches58aare joined to the slats62bthe bushing58is engaged such that the bushing58will have little rotation relative to the lower grip portion24b, and as such the actuator20will have reduced “slack” to be taken up by the operator before the distal end will deflect in the desired direction. In a preferred embodiment, the bottom of the bushing58can have cross hatching or other patterns cut onto its outer surface to facilitate mating with, or bonding to the inside of the landing62a.

As shown inFIGS. 12B and 12C, the auto-locking mechanism can further include a tensioning member200. For example, as shown inFIG. 12B, a Belleville washer202can be placed between the bushing58and the actuator20. As shown inFIG. 12C, a Belleville washer204can be placed between the landing62aand the actuator20.

In operation, the components of the auto-locking mechanism may swell or shrink due to excessive heat or cold. The tensioning member200will operate to either take up the slack, or to provide room for expansion, while at the same time maintaining a constant tension T. This advantageously ensures that the operator will experience the same desirable level of thumb force to operate the actuators as set during manufacturing. Such a tensioning member could be a Belleville washer as shown inFIGS. 12B,12C, or another tensioning apparatus. In addition to the locations shown inFIGS. 12A-12C, above, the tensioning member200can be placed at any other point in the auto-locking mechanism54where it will provide for a constant tension.

For example, as shown inFIG. 13A, a tensioning member such as a spring210can be placed in a gap between landing62aand pivot point62. The bushing58can slip over the pivot point62and rest an optional washer56that rests on the spring210. As with a Belleville washer, the spring can be located in a variety of locations, so long as it provides for a relatively constant tension T on the actuator20to keep a constant thumb force for moving and automatically locking the actuator20. As shown inFIG. 13B, the spring212can be located between washer56and actuator20, or as shown inFIG. 13C, the spring214can be located between the screw60and the bushing58.

FIG. 14depicts another variation of the invention, in which a bushing224includes notches224acut in its bottom portion that are designed to mate with slats62b. The slats62bare located in the space between the pivot point62and the landing62a. When the notches224aare joined to the slats62bthe bushing224is engaged such that the bushing224will have little rotation relative to the lower grip portion24b, and as such the actuator220will have reduced “slack” to be taken up by the operator before the distal end will deflect in the desired direction. In a preferred embodiment, the bottom of the bushing224can have cross hatching or other patterns cut onto its outer surface to facilitate mating with, or bonding to the inside of the landing62a. The bushing224can be epoxied to the pivot point62and/or the landing62a.

The bushing224can be constructed from any material, especially a durable polymer, a stainless steel, or brass. Ideally the material selected will be sufficiently durable to endure long periods of sitting under compression tension, and also have a low frictional range allowing ready movement between the bushing224and the actuator components.

The bushing224may also have a D-shaped top surface232. The bushing includes a bushing landing surface234that rests on the landing62a. The bushing landing surface234and the sides of the bushing224may be polished, e.g., to 8 microns, to maintain cycle durability. The actuator220includes an integral actuation washer portion222. The actuator220is slid over the bushing224. A D-shaped washer226is then mated with the D-shaped top surface232. A washer228rests between on the D-shaped washer226. A nut230is then attached to threaded surface236and tightened to a tension T, e.g., 5-6 pounds of force, and a drop of thread lock is added.

In this aspect of the invention, the vertical load path advantageously runs only from bushing224, its landing234, through actuator220to D-shaped washer226, optional washer228, and nut230. In particular, the load path does not include the polycarbonate upper or lower grip portions24a,24b, and thus does not place a long term stress on these portions.

As shown inFIG. 15, the washer228may be replaced by a tensioning member such as a Belleville washer240. Likewise, as shown inFIGS. 15A,15B, a tensioning member such as a spring242or244may be employed. As detailed above, the tensioning member will operate to either take up the slack, or to provide room for expansion, while at the same time maintaining a constant tension T. In addition to the locations shown inFIGS. 15-15C, above, the tensioning member can be placed at any other point in the auto-locking mechanism54where it will provide for a constant tension.

As shown inFIG. 16, an actuator250can include a post258designed to attach to upper and lower grip portions24a,24bby sliding over or otherwise attaching to pivot base62on lower grip portion24band pivot base262on upper grip portion24a. Actuator250includes a first post252attached to a spring256, e.g., a tension spring or extension spring. The spring256is attached to a second post254, which is attached to lower grip portion24b. In operation, as the actuator250is pivoted on post258, the distal end18of the catheter is deflected, and will exert a force F toward returning to the distal end's zero point. The spring256, actuator250, post252, and post254are placed such that the spring is at its longest when the actuator is at its middle point. When the actuator250is pivoted away from its middle point, the length between posts252,254is shortened, thus shortening the spring256. Thus, to return to the actuator250's middle point, a force F1must be exerted to lengthen the spring256. This force F1will oppose the force F, and preferably exceed the force F. That is, the force F generated by the distal end18seeks to return the distal end18to its zero point, and thus return the actuator250to its middle point. The Force F1generated by the spring256seeks to move the actuator further to the left or right of its middle point, and thus move the distal end to the left or right. As a result, the spring256acts as a tensioning member200in the auto-locking mechanism. As is known to one or ordinary skill in the art, the motion of the actuator250, spring256, and posts252,254may be aided by means of gears placed in relation to the post to lengthen or shorten the distance between the posts252,254during motion of the actuator250.

The actuator of the present invention may assume numerous physical formats, and is not limited to an actuator of the shape shown in the drawings. For example, the actuator20could assume a T-shape, or could be round. As shown inFIG. 17, an actuator280can include a post288designed to attach to upper and lower grip portions24a,24bby sliding over or otherwise attaching to pivot base62on-lower grip portion24band pivot base262on upper grip portion24a. The actuator280may have depressible levers284,282, which must be depressed by the operator in order for actuator280to pivot. The levers284,282are connected to a locking mechanism inside the actuator20that must be released before rotational motion is possible.

As shown inFIG. 18, a rotatable post290may be in frictional contact with actuator292on post294. In operation, as the actuator292is pivoted on post294, the distal end18of the catheter is deflected, and will exert a force F toward returning to the distal end's zero point. The rotatable post290must overcome a force F2, e.g., a frictional force, to rotate. Accordingly, the force F2counteracts, and preferably exceeds, the force F exerted by the distal end18. As a result, the rotatable post290acts as a tensioning member200in the auto-locking mechanism.

Although embodiments of this invention have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention. The actuator of the present invention may assume numerous physical formats, and is not limited to an actuator of the shape shown in the drawings. For example, the actuator20could assume a T-shape, or could be round.