One-motion handle for steerable catheters

Abstract

A control handle for a steerable catheter allows for precise manipulation of the distal catheter tip in a target organ or vessel using only one hand. The control handle can have a single articulation knob capable of both linear translation along the handle's axis and rotation about the handle's axis. These functions of the articulation knob actuate both the extension and retraction of the expandable member and bidirectional deflection of the distal catheter tip. The articulation knob functions consistently regardless of handle orientation, providing ergonomic movement that allows the user to comfortably maintain attention on procedural monitoring equipment. These improvements can lead to safer and faster procedure times for procedures such as diagnostics and cardiac ablation.

Description

[Technical Field]

[0001] The present disclosure relates generally to control handles for intravascular catheter systems, and more particularly, the present disclosure relates to an improved handle for a steerable catheter that can be operated with one hand. [Background technology]

[0002] Abnormal or irregular electrical signals in areas of cardiac tissue can disrupt normal heart rhythm. Cardiac arrhythmias result from irregular heartbeat cycles in which these electrical signals are not properly coordinated. Such conditions, including paroxysmal atrial fibrillation (PAF), are often treated either by disrupting the source of the signals or by severing the signal's conduction pathway through the pulmonary veins.

[0003] Many procedures require the use of multi-function catheters with tip mechanisms that can be steered or expanded and retracted. Many such procedures, such as diagnostic mapping and ablation, require a high level of precision. Ablation techniques are commonly used to stop or modify the propagation of unwanted electrical signals from one part of the heart to another. This process involves applying energy to tissue from an electrode, which disrupts the unwanted electrical pathway through the formation of a non-conductive lesion. The applied energy can be radiofrequency (RF), cryotherapy, irreversible electroporation (IRE), or other similar techniques. Successful patient outcomes often depend on precisely targeted isolation of pulmonary veins in the subject's left atrium to eliminate symptoms. The deployment of precision ablation assemblies into specialized catheters for deliverability and expanded configurations after delivery creates a continuing challenge to improve the control elements for these systems.

[0004] A typical catheter system usually involves an elongated, flexible catheter shaft extending from a proximal luer or control handle containing an actuation mechanism. Some of these catheters are capable of delivering a steerable tip to the heart or other tissues of the body for purposes of ablation, diagnosis, and other functions to assist in therapy. The use of a radially expanding device with RF electrodes to form circumferential lesions at or near the ostium of a pulmonary vein to treat atrial arrhythmias is disclosed in U.S. Patent Nos. 6,012,457 and 6,024,740, both to Lesh. Additionally, U.S. Patent Publication No. 2016 / 0175041 to Govari et al., assigned to the present applicant and incorporated herein by reference, utilizes a catheter with an expandable balloon having an electrode assembly disposed around its exterior so that atraumatic contact with the venous ostium can create a consistent, circumferential lesion surrounding the vein.

[0005] However, intravascular procedures using steerable catheters remain hampered by the difficulty experienced by users when attempting to steer the catheter tip to a precise tissue location. Even existing catheters with steerability and deflection control often have limited steering capabilities. This is especially true for procedures requiring fine movement control. Furthermore, existing designs often only allow deflection along a single plane, meaning users must rotate the entire device to access three-dimensional locations that are not parallel to the deflection plane. This combination of factors can make many procedures, such as aligning ablation electrodes, difficult and time-consuming. Uneven or incomplete ablation can lead to debris embolization or even treatment failure, and long fluoroscopy and procedure times can also lead to complications.

[0006] Additionally, attention to detail and knowledge of exactly how a particular instrument responds to inputs are critical to a successful procedure. The control member or handle is important for maneuverability and steering of the catheter shaft, both for passage through the aortic arch and for positioning for the ablation process. Often, there is a lever or rotating member on the handle that controls the tip, causing deflection. Slidable buttons or toggle mechanisms can also be used. Precision and comfort of the handle are important, as significant injury to the patient can occur if the catheter is redirected, deflected, or rotated in the wrong direction. Similarly, a physician having to repeatedly look away from the diagnostic tool to determine where their hands are positioned and which part of the handle needs to be actuated can add significant time to a surgical procedure.

[0007] Examples of several different handle mechanisms for control of catheters and catheter tips designed for electrophysiological mapping and / or ablation can be found in the art. U.S. Patent No. 5,944,690 to Falwell et al. discloses a steerable catheter control design that utilizes a slider mechanism to manipulate a control wire. However, depending on the position of the slider mechanism, the design may require an awkward twist of the hand to allow the thumb or another finger to further adjust the slider. A single slider may also lack the precision necessary for fine manipulation and adjustment of the catheter.

[0008] For ablation procedures, the geometry and size of pulmonary veins often require ablation diameters significantly larger than typical delivery catheters or sheaths. As a result, many circumferential ablation devices are required to have both a flexible, small profile for delivery within an outer catheter and a deployed, expanded configuration at the target site for precise ablation and diagnosis. Actuating this expansion often requires additional functionality, attachments, or devices connected to or delivered through the handle, complicating setup and requiring additional hands to operate. Similar capabilities are also needed to retract the device for retraction into the sheath or outer catheter upon completion of the procedure.

[0009] U.S. Patent Publication No. 2019 / 0083751 to Buesseler discloses a plunger- or slider-type actuation mechanism for a medical device having a deflectable distal region. The device utilizes pinching of a control wire as a means to secure or self-lock the mechanism, eliminating the need for a secondary locking mechanism and reducing operator fatigue. However, plunger-type mechanisms also have limited fine adjustment capabilities. Furthermore, these designs lack the ability for further expansion or deployment beyond tip manipulation.

[0010] U.S. Patent Publication No. 2016 / 0331932 to Davies et al. discloses a control handle for a steerable catheter that utilizes control wires articulated by one or more handle-mounted rotation knobs. Tensioning the wires causes distal deflection of the catheter tip. However, this design can have multiple knobs on both the proximal and distal ends of the handle, which can require multiple hands to operate in certain situations, while also lacking the ability to activate additional functions beyond steering the tip.

[0011] Different physicians may also have different preferences in how they prefer to hold the handle during a procedure. Conventional handles or systems may have various control surfaces that may be located proximally or distally on the handle, which requires the physician to significantly adapt based on personal preferences and / or particular hand dominance. Thus, these designs may not provide the necessary comfort for the user while manipulating and adjusting the handle. Summary of the Invention [Problem to be solved by the invention]

[0012] Therefore, there is a need for improved devices, systems, and methods for a control handle that allows for precise steering control of the deflectable tip while also being able to actuate additional tip functions, such as expanding and contracting the expandable member. It is also highly desirable that the ergonomics of the handle allow for articulation of these functions to be performed with one hand so as to avoid operator fatigue. [Means for solving the problem]

[0013] It is an object of the present invention to provide systems, devices, and methods that meet the above-mentioned needs. Generally, there is a particular need for precise control and actuation of catheters having mechanisms and devices capable of extension and retraction and multi-directional deflection. In many cases, a device capable of consistent performance during a procedure must be capable of actuation between a collapsed delivery state and a deployed, expanded state sized to deliver energy around the entire ostium or to detect cardiac signals for diagnostics over a significant area. While often mentioned in connection with cardiac ablation or diagnostic procedures as examples, many other potential applications for such control handles can be envisioned, with any intravascular procedure requiring remote actuation of an expandable member at a target site being a candidate.

[0014] A control handle for a catheter having a steerable tip can have an outer housing having a substantially tubular shape, a proximal end, and a distal end. An articulation knob for controlling functions of the catheter tip can be positioned near the distal end and configured to be rotatable about and linearly displaceable along the longitudinal axis of the handle's outer housing. The handle housing and knob can be sized so that all functions and movements of the knob can be comfortably performed with one hand, so that the user does not have to look down to reference the respective positions of the handle components or use another hand for manipulation during a procedure. Movably disposed within the outer housing can be a drive housing longitudinally coupled to the articulation knob. Movement of the drive housing can actuate a control member to initiate functions of the handle. The control member can include a component such as a control wire, a sliding lever, or a toggle.

[0015] In one embodiment, the catheter can have an electrode at its steerable tip to be used for ablation of tissue in or around the heart to form enhanced lesions as a treatment for disrupting undesired cardiac electrical signals. For example, one or more independently controlled electrodes can be disposed on the surface and evenly spaced around the circumference of an inflatable balloon. In another embodiment, the electrodes can be located on the exterior of a structure that can be configured to expand when deployed from the delivery catheter at the target site. In this configuration, the catheter can have one or more Luer fittings configured to receive fluid injection for irrigation of the ablation site and / or cooling of the tip electrode.

[0016] In another example, the catheter may have a tip that can be triggered to expand in radial size or change shape, for example, to perform electrophysiological mapping and imaging of healthy and unhealthy cardiac tissue. Such systems are also often capable of determining the velocity and direction of cardiac signals.

[0017] The articulation knob can be configured to impart first, second, and third linear displacements to the drive housing parallel to the longitudinal axis of the handle outer housing. In some cases, the first linear displacement of the drive housing activates a function of a first control member of the steerable tip, and the second linear displacement activates a function of a second control member. The first linear displacement can occur when the knob is rotated clockwise about the longitudinal axis, and the second linear displacement can occur opposite the first linear displacement when the knob is rotated counterclockwise. These opposing displacements tension control wires or cables coupled to the distal end of the catheter, angularly deflecting the steerable tip in opposite directions to direct fine movement of the tip at a target site in the vasculature.

[0018] A third linear displacement of the drive housing can occur when the articulation knob is translated a distal or proximal distance parallel to the longitudinal axis. Linear translation of the knob can be achieved independently of any rotation imparted to the knob. This movement can be configured to change the radial size of an expandable member at the distal tip of a steerable catheter, such as an ablation balloon system for treating arrhythmias or a diagnostic tool configured to record cardiac signals from tissue. This radial size can be actuated and controlled by an advancement mechanism coupled proximally to the drive housing and distally to the expandable element. Distal translation of the articulation knob can push the advancement mechanism distally to axially extend or lengthen the expandable element, reducing its corresponding radial size. Similar proximal linear translation of the knob can pull the advancement mechanism to axially shorten and expand the expandable element. To achieve this actuation, the advancement mechanism can be constructed from a tough yet flexible organic material, such as polyimide tubing.

[0019] The advancement mechanism can be an elongated tubular member and can have a hollow interior lumen that allows the advancement mechanism to be used for distal delivery of various auxiliary devices or therapies, such as guidewires, microcatheter-based systems, mapping catheters, or contrast agents.

[0020] In further examples, the situation can be reversed where linear translation of the articulation knob along the longitudinal axis actuates the steerable tip to angularly deflect in the opposite direction to direct fine motion control, and rotation of the articulation knob can be configured to control the radial size of the expandable element, thus allowing functionality to be tailored to the ergonomic preferences of a particular user or the ease of performing a particular procedure.

[0021] The articulation knob of the control handle can include a hub, a proximal end, and a distal opening through which the catheter body and any associated internal components, such as the advancement mechanism and control member, can pass to the exterior of the handle. The inner diameter of the knob hub can have at least one keyway machined or formed into its surface. Rotatably coupled to the articulation knob can be a barrel nut. The barrel nut can include one or more keys, a thrust collar, and an internal drive spline. The keyway in the knob hub can transmit torque to a key in the barrel nut, which can be longitudinally rotationally coupled to the drive housing via the threads of the thrust collar and drive spline, respectively. The thrust collar can act as a mechanical stop for transmitting linear displacement to the drive housing.

[0022] The drive housing can have a split piston carriage that can include a right flexure rack and a left flexure rack that are controllably movable relative to one another within the outer housing. Distal portions of the right and left flexure racks can form drive bolts with external threads configured to engage with the female drive spline threads of the barrel nut. A pinion gear engages with internal axial teeth of the right and left flexure racks and can rotate when there is relative movement between the racks. Clockwise rotation of the articulation knob can result in translation of the right flexure rack along a linear path relative to the left flexure rack in a first direction, tensioning a wire or other control element. Similarly, counterclockwise rotation of the knob can result in a second relative linear translation in a second direction opposite the first direction, tensioning the same or a different wire or control element.

[0023] Features such as relief notches or detents can be machined into various components of the handle, such as the knob, drive bolt, drive housing, or barrel nut, at various axial or clocking locations to serve as engagement points for selectively maintaining a particular tip deflection or radial size of the expandable element. Alternatively, elements can be used to create a friction lock to hold the position of the articulation knob relative to the handle to prevent unintended movement during a procedure. These elements can be rubber seals, grommets, or other common components known in the art. Thus, the knob assembly can be capable of maintaining specific angular and longitudinal positions to correspond to a desired discrete deflection or radial size of the expandable element.

[0024] In another example, the handle portion that controls the steerable catheter can include a deflection thumb knob that allows bidirectional deflection, a balloon disposed around or connected to the distal portion of the catheter body, a balloon advancement mechanism, and a luer fitting for balloon inflation and irrigation. An additional luer fitting can be located near the distal end of the handle portion with a lumen that extends through the handle, catheter body, advancement mechanism, and balloon and is in fluid communication with the distal-most tip of the catheter. This luer fitting and lumen can serve as an entry port for a guidewire or other small device, as well as provide irrigation and contrast injection distal to the balloon of the catheter.

[0025] Also provided is an exemplary method for controlling a steerable catheter with a control handle during an intracardiac procedure. The method may include any of the following steps, presented in any order. An example may include introducing a steerable catheter into the vascular system, the catheter including a catheter shaft having a proximal region, a deflectable distal region, and a control handle. The control handle may have an outer shell, a distal knob assembly capable of linear translation along and rotation about a longitudinal axis of the handle, and a drive assembly movably disposed in the outer shell. The drive assembly may have an inner housing, a distal drive bolt, and a split piston carriage threadably engaged with the distal knob assembly.

[0026] The distal knob assembly can be linearly displaced along the longitudinal axis to actuate expansion or retraction of an expandable element on the distal end of the steerable catheter. In embodiments, linearly displacing the knob proximally relative to the outer shell can increase the radial size of the expandable element, while corresponding distal displacement can decrease the radial size. Rotation of the distal knob assembly about the longitudinal axis can cause angular deflection of the steerable tip by actuating a control member, which can be coupled to a drive assembly. Clockwise rotation of the knob can deflect the tip in one direction, while corresponding counterclockwise rotation can deflect the tip in the opposite direction along the same plane.

[0027] Method steps involving rotation and translation of the distal knob assembly can occur independently of one another. For example, to facilitate delivery to a targeted site for ablation, the knob can be positioned so that the expandable element assumes a small radial size. Upon reaching a site just proximal to the target, the expandable element can be expanded through proximal translation of the knob to a desired larger radial size based on the size of the patient's ostium. Thus, an expandable element, such as an ablation balloon with independently controlled electrodes around its circumference, can be prepared for treatment without tip deflection or tissue contact. The desired radial size of the expandable element can then be maintained while final steering adjustments are made by rotating the knob to deflect the distal tip into place.

[0028] Additionally, the handle can be held in one hand while flexing and rotating the knob is performed with the thumb and fingers of the same hand. By not requiring the other hand, the user does not have to look away from the procedure to refer to the handle's position or orientation, allowing them to maintain their attention on the associated monitoring equipment for the procedure.

[0029] The method can further include including an internal physical stop or another similar method that limits the translational, rotational, or both translational and rotational movement of the knob assembly of the handle. Limits can be established so that the physician is aware of the absolute movement capabilities and performance of the catheter before and during the procedure. For example, knowing these limits can be advantageous in situations where tip deflection is out of plane at the physician's viewing angle. Intermediate axial positions of the knob can also be configured to correspond to discrete radial sizes of the expandable element so that the expandable element can conform to different anatomical shapes.

[0030] Another method for manipulating a distal tip of a catheter with only one hand can include positioning the catheter within a blood vessel. The catheter can have an elongate tubular member having a steerable distal tip and a control handle proximal to the elongate tubular member. The control handle can have an outer housing and a control knob configured for translational and rotational movement relative to the outer housing. Within the outer housing can be a control assembly coupled to the control knob such that linear displacement and angular rotation of the control knob actuates a control function at the distal tip of the catheter.

[0031] Actuation can occur through multiple methods, such as tensioning a control wire and / or using a post to exert an axial thrust load on a portion of the distal tip of the elongate tubular member. Once the tip is positioned proximal to the target location, the control knob can be linearly displaced along the longitudinal axis of the housing to expand and deploy the expandable element at the distal tip. Grooves or recesses can be configured in the handle to allow the control knob to maintain specific intermediate discrete angular or axial positions. The element can take many forms, such as a balloon with multiple independently controlled electrodes configured around its circumference for ablation of pulmonary veins. To further orient the tip, the control knob can be rotated clockwise to deflect the distal tip in a first direction or counterclockwise to deflect the tip in a second direction opposite the first direction.

[0032] Multiple independently controlled electrodes can be evenly spaced around the circumference of the expandable element. The expandable element can be manipulated to make circumferential line contact with the wall of the pulmonary vein, and tissue surrounding the line contact can be ablated by directing energy from an energy source, such as an RF generator, through conductors to the electrodes. A further step can involve using the control handle to orient the tip to isolate subsequent ablation locations during the procedure. Once ablation is complete, the handle control knob can be linearly displaced distally to collapse the expandable element to a smaller radial size, so that the expandable element can be reloaded into a sheath or outer catheter for extraction from the patient.

[0033] Additional steps in addition to those enumerated herein may be included as will be recognized and understood by one of ordinary skill in the art. The exemplary methods may be performed by the exemplary control handles disclosed herein, variations thereof, or alternatives thereof, as will be understood by one of ordinary skill in the art.

[0034] Other aspects and features of the present disclosure will become apparent from the following detailed description considered in conjunction with the accompanying figures. [Brief explanation of the drawings]

[0035] The above and further aspects of the present invention will be further discussed with reference to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in the various drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. The figures depict one or more implementations of devices of the present invention, by way of example only, and not by way of limitation. [Figure 1] FIG. 1 is a system level diagram of a control handle operable with one hand and capable of actuating multiple functions at the distal tip of a steerable catheter, according to an aspect of the present invention. [Figure 2] FIG. 1 is an isometric view of a control handle according to an aspect of the present invention. [Figure 3] 3 is a top view of the control handle of FIG. 2 in accordance with an embodiment of the present invention. [Figure 4] FIG. 3 is a side view of the control handle of FIG. 2 in accordance with an embodiment of the present invention. [Figure 5] 1 is an illustration of a control handle with the top portion of the outer housing removed, according to an aspect of the present invention. [Figure 6] 1 is an example of an expandable ablation balloon that can be both expanded and deflected by a control handle, according to an aspect of the present invention. [Figure 7] FIG. 10 is a cross-sectional side view of a control handle showing the handle interfacing with a drive housing, according to an aspect of the present invention. [Figure 8] FIG. 10 is a cross-sectional view from above of a control handle showing the handle interfacing with a drive housing, according to an aspect of the present invention. [Figure 9] FIG. 9 is an enlarged cross-sectional view of the cross-section from FIG. 8 showing the connection between the barrel nut and the piston carriage, according to an embodiment of the present invention. [Figure 10] 10 illustrates a drive housing and piston carriage of a control handle without an outer housing, articulation knob, or barrel nut, according to an aspect of the present invention. [Figure 11] FIG. 11 is a cross-sectional view from FIG. 10 just distal to the pinion, in accordance with an embodiment of the present invention. [Figure 12a] 10A-10C illustrate right and left flexure racks, respectively, in accordance with aspects of the present invention. [Figure 12b] 10A-10C illustrate right and left flexure racks, respectively, in accordance with aspects of the present invention. [Figure 13] 1 illustrates the lower half of the drive housing of the control handle, according to an aspect of the present invention. [Figure 14a] FIG. 10 is an isometric view of an articulation knob of a handle according to an aspect of the present invention. [Figure 14b] FIG. 10 is a cross-sectional view of an articulation knob according to an aspect of the present invention. [Figure 14c] FIG. 10 is a perspective view of an articulation knob from the proximal end, according to an aspect of the present invention. [Figure 15] FIG. 10 is an isometric view of a barrel nut of a handle according to an aspect of the present invention. [Figure 16] FIG. 1 is a cross-sectional view of a barrel nut according to an aspect of the present invention. [Figure 17a] 1A-1C illustrate an embodiment of an expandable ablation balloon as operated by an advancement mechanism in its delivery configuration and expanded deployed configuration, respectively, according to an aspect of the present invention. [Figure 17b] 1A-1C illustrate an embodiment of an expandable ablation balloon as operated by an advancement mechanism in its delivery configuration and expanded deployed configuration, respectively, according to an aspect of the present invention. [Figure 18] 1 illustrates a shaft of a steerable catheter according to an aspect of the present invention. [Figure 19] FIG. 19 is an enlarged cross-sectional view of the shaft of FIG. 18 showing some of the internal control elements, according to an embodiment of the present invention. [Figure 20a] 10A-10C are a series of cross-sectional views illustrating how different displacements and rotations of the articulation knob affect the function of the distal tip of the steerable catheter, according to aspects of the present invention. [Figure 20b] 10A-10C are a series of cross-sectional views illustrating how different displacements and rotations of the articulation knob affect the function of the distal tip of the steerable catheter, according to aspects of the present invention. [Figure 20c] 10A-10C are a series of cross-sectional views illustrating how different displacements and rotations of the articulation knob affect the function of the distal tip of the steerable catheter, according to aspects of the present invention. [Figure 20d] 10A-10C are a series of cross-sectional views illustrating how different displacements and rotations of the articulation knob affect the function of the distal tip of the steerable catheter, according to aspects of the present invention. [Figure 20e] 10A-10C are a series of cross-sectional views illustrating how different displacements and rotations of the articulation knob affect the function of the distal tip of the steerable catheter, according to aspects of the present invention. [Figure 20f] 10A-10C are a series of cross-sectional views illustrating how different displacements and rotations of the articulation knob affect the function of the distal tip of the steerable catheter, according to aspects of the present invention. [Figure 21] 1 illustrates an example of an expandable ablation balloon with independently controlled electrodes around its circumference for performing ablation of pulmonary veins, according to aspects of the present invention. [Figure 22] 1 is a flow chart outlining a method for using a control handle to operate a distal tip of a steerable catheter, according to an aspect of the present invention. [Figure 23] 1 is a flow chart outlining a method for using a control handle to operate a distal tip of a steerable catheter, according to an aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] Specific embodiments of the present invention will now be described in detail with reference to the drawings, where like reference numbers indicate functionally similar or identical elements. The drawings illustrate a control handle for a steerable catheter that can be operable with one hand to improve ergonomics for the operator while controlling the steerable and expandable functions of the catheter's distal tip. The control handle's articulation knob functions consistently regardless of handle orientation, providing ergonomic movement that allows the user to comfortably maintain attention on monitoring equipment while performing a procedure. These improvements can lead to safer and faster procedure times.

[0037] Although often referred to herein in connection with ablation procedures, it should be understood that the disclosed control handles can be applicable to catheters having activated tip mechanisms for a variety of procedures, such as mapping or diagnosis. Accessing various vessels within the vascular system, whether coronary, pulmonary, or cerebral, involves well-known procedural steps and the use of many conventional, commercially available accessory products. These products, such as angiographic materials, rotating hemostatic valves, and guidewires, are widely used in laboratories and medical procedures. When these products are used with the systems and methods of the present invention in the following description, their function and exact configuration will not be described in detail. While the description is often related to cardiac ablation therapy, the systems and methods may be used for other procedures and in other body passageways as well.

[0038] Steerable catheters or sheaths can be utilized to gain access to target locations within the body. Such devices can have control mechanisms for providing access to areas of the body through the vascular system using minimally invasive procedures. In some of these procedures, the tip of the catheter or sheath may be required to deflect in more than one direction to provide access. In other procedures, the tip may require expandable functionality at the target site.

[0039] Turning to the drawings, FIG. 1 illustrates a steerable control system or handle 100 for manipulating a medical device while performing an endovascular procedure. The medical device may include, by way of example, a catheter, sheath, introducer, or similar device. Such devices are often used for cardiac ablation, mapping, diagnostics, thrombectomy, and other procedures. The handle 100 may be coupled to a catheter shaft or sheath 27 to allow a user to orient and steer the shaft using the handle. The handle 100 may include an articulation knob 210 coupled to an outer shell or housing 110. The knob 210 may be independently rotated and linearly translated relative to the handle outer shell 110. The handle 100 may further include a connection for a catheter cable 30 coupled to a diagnostic hub of a function generator or navigation system for transmitting and / or receiving data during the procedure.

[0040] In some cases, the handle 100 can have one or more Luer fittings 40 for injecting fluid through the outer housing 110 using a syringe, pump, or other means. The fluid can be contrast, saline, or other solution and can be used for any of a number of purposes, depending on the procedure. These can include angiography, irrigation, cooling, or inflation of a balloon or other inflatable member.

[0041] In use, rotation of the articulation knob 210 in a first, clockwise direction relative to the outer housing 110 of the handle 100 can allow a user to deflect and steer the deflectable segment 26 of the catheter shaft 27. Similarly, rotation of the knob in a second, counterclockwise direction can allow deflection and steering in the opposite direction. In other embodiments, a bi-directionally steerable catheter is configured to deflect in two separate deflection directions that are out-of-plane with each other.

[0042] Linear deflection of the articulation knob 210 relative to the outer housing 110 of the handle 100 can control different functions of the catheter's steerable distal tip 50. For example, the degree of proximal or distal axial displacement can vary the radial size of the steerable tip's expandable element, which can be deployed from a smaller delivery configuration to an expanded, deployed state that may be necessary to perform a particular procedure. When the catheter tip 50 needs to be repositioned or at the end of a procedure, axial displacement in the opposite direction to that used to expand the element can be applied to return the element to a smaller size or profile for steerability.

[0043] 2-4 show different orientations of the control handle design. Referring to FIG. 2, the outer housing 110 of the control handle 100 can be generally tubular in shape. The catheter shaft 27 can extend through the distal end 113 of the handle 100. The articulation knob 210 can be located distal to the outer housing 110 so that when the handle is held in the palm of a hand, all of the knob's functions can be operated using the thumb and / or index finger of the same hand. The catheter shaft 27 can extend inside the outer housing 110 so that the shaft is not impacted by the knob and the knob is free to translate and rotate through its full range of motion. The proximal end 112 of the handle 100 can have additional attachments or passageways for other auxiliary devices necessary for the desired procedure or for additional fluid injection for irrigation and / or contrast media.

[0044] The elements visualized in the drawings can be described as tubular structures and are generally illustrated as substantially right cylindrical structures. However, as used herein, the terms "tubular" and "tube" are intended to be interpreted broadly. They are not meant to be limited to structures that are right cylindrical, i.e., strictly circular in cross section or of uniform cross section throughout their length.

[0045] The outer housing 110 of the handle 100 can be split in half for manufacturing and assembly, as seen in FIG. 4. The housing can have an upper shell 120 and a lower shell 130 that may or may not be equal in radial size and can be secured together within the enclosure by fasteners, a snap fit, adhesive, or other suitable means. The outer housing 110 can house all of the actuation of the handle's control functions so that there are no sharp edges or buttons to snag and the articulation knob 210 is the only movable control surface.

[0046] Referring to FIG. 5 , outer housing 110 provides a hollow shell to enclose drive housing 410, allowing linear translation of the drive housing therein along longitudinal axis 111. This view depicts the assembly with articulation knob 210 and the upper half of the outer housing removed, with drive housing 410 disposed within outer lower shell 130 and sharing longitudinal axis 111. The drive housing may be coupled axially to the articulation knob such that linear translation of the drive housing within the outer housing is directly driven by linear translation imparted to the articulation knob by the user. Catheter shaft 27 may be coupled proximally within a portion of drive housing 410 such that it is controlled by rotational and translational motion of handle 100. The handle may terminate at a proximal end 112 that can be used to interface with a cabled connector or additional Luer fitting for irrigation or contrast injection. Alternatively, proximal end 112 may have a secondary entry point for a guidewire or similar small diameter device.

[0047] The catheter's distal tip 50 can take many forms, depending on the needs of the procedure being performed. The handle 100 can be useful with any distal tip design that can expand and collapse, or change its shape configuration. In one embodiment, the tip can have an expandable cage or basket-like structure, or can be configured to monitor and map cardiac signals for diagnostic purposes. In another embodiment, the catheter can be adapted to deliver energy for cardiac ablation. The catheter's distal tip 50 in this embodiment can be an expandable balloon ablation system, as seen in FIG. 6 and described in the aforementioned U.S. Patent Publication No. 2016 / 0175041. In this embodiment, a compliant balloon 610 can be used to isolate pulmonary veins in the subject's left atrium. The balloon 610 can expand into a generally spherical or oval shape about the longitudinal axis 51 of the tip 50. The distal end 614 of the balloon can be atraumatically tapered into an extension collar 630 proximate the distal end of the balloon.

[0048] A lumen 622 can extend through the catheter shaft 27, the balloon 610, and the extension collar 630. The lumen 622 can provide distal access to the ablation site and can function as distal irrigation, contrast injection, and / or a delivery channel for guidewires and other small diameter devices. For example, a 0.050 inch lumen diameter can accommodate guidewires up to 0.035 inch while maintaining irrigation through the lumen 622 to prevent blood clotting.

[0049] The high torque shaft 27 can enable the steerable catheter tip 50 to have the deliverability and level fidelity needed for precise procedures. The shaft can transition distally to a steerable, deflectable tip segment 26 controlled by the handle 100. Inside the tip segment 26, not shown in FIG. 6, can be leads for the electrodes 616 and control elements for deflection of the tip 50.

[0050] Some or all of the catheter shaft 27 or tip 50 can also have additional features for deliverability and torque transmission, such as directional braiding or a selectively elastic polymer jacket. A high-torque shaft allows the plane of the deflected tip to rotate to facilitate precise positioning at the target site, such as the ostium of a pulmonary vein. Torque transmission capabilities are also useful when the catheter tip has a balloon with circumferential electrodes, but its shape may otherwise limit translation in certain directions when deployed. The stiffness and torque characteristics of the shaft 27 add smooth pushability, while the flexible compliance of the balloon 610 allows for atraumatic conformance of the balloon 610 with local tissue anatomy so that the circular alignment of the electrodes 616 can achieve proper contact with the venous ostium.

[0051] The outer surface of the balloon 610 can have multiple independently controlled electrodes 616 bonded to the surface of the balloon and circumferentially oriented to create a circular contact profile with the pulmonary vein ostium. The electrode shape can be selected to allow similar inter-electrode spacing axially across varying diameters of the expanded balloon between the proximal end 612 and the distal end 614. Each electrode can be gold-plated for electrical conductivity and perforated with individual holes to allow fluid flow from inside to outside the balloon. For example, heparinized saline can be delivered through the Luer fitting 40 of the handle 100 for irrigation flow.

[0052] The electrodes 616 can extend from the proximal end 612 to the distal end 614 of the balloon 610 in a flexible circuit. Having independently tensioning electrodes in this manner allows each electrode to have a conductor, such as a bifilar wire, routed through the catheter shaft 27 to independently deliver energy and act as a thermocouple to detect temperature at each electrode interface. Energy can be delivered using RF, cryogenics, IRE, or other similar techniques.

[0053] A cross-sectional side view of the handle from FIG. 3 is illustrated in FIG. 7. The articulation knob 210 may be axially secured to the drive housing 410, such as with a collar, retaining ring, or set screw, so that they translate as a pair. In the embodiment in FIG. 7, a thrust collar 314 can transmit pushing / pulling forces between the knob and the drive housing. When secured in this manner, when the knob is displaced distally or proximally along the longitudinal axis 111 relative to the outer housing 110, the same displacement is experienced by the drive housing. Alternatively, a portion of the articulation knob can extend proximally to be received within the drive housing, where it may be secured via a set screw or other means. The outer housing 110 may be configured to guide the linear displacement of the drive housing 410 while simultaneously restricting or limiting the total range of travel available to the drive housing. Because they may be coupled, this limit on the displacement of the drive housing 410 may also be experienced by the articulation knob 210.

[0054] Linear deflection of the articulation knob 210 of the handle 100 can be translated into expansion or retraction of the expandable element via movement of the drive housing 410 within the outer housing 110. Alternatively, linear deflection of the articulation knob 210 can be used to deflect the catheter tip in a direction related to the induced relative motion of the drive housing 410. Actuation of the expandable element from the control handle can provide procedural advantages and eliminate the need for a separate expansion mechanism incorporated into the handle for this purpose. For example, as seen in FIG. 6 , the proximal end 612 or distal end 614 of the balloon 610 can have an extension collar 630 that can be slidably disposed along the tip axis 51 and longitudinally coupled to the drive housing 410 within the handle 100. In this configuration, linear translation of the drive housing in a first direction can increase the radial size of the balloon, and translation of the drive housing in a second direction opposite the first direction can decrease the radial size of the balloon.

[0055] Rotation of the articulation knob 210 of the handle 100 can be translated into angular deflection of the catheter shaft 27 or expansion of an expandable member at the catheter tip 50 via relative motion of the drive housing 410 within the outer housing 110. A piston carriage 510 on the drive housing 410 can have an external thread alignment that is received within a barrel nut 310 with a corresponding internal thread alignment and is rotatably coupled to the articulation knob 210. The threads allow the knob 210 to linearly translate the piston carriage 510 on the drive housing 410 as the knob is rotated.

[0056] In one embodiment, piston carriage 510 can have multiple cooperatively engaging parts or assembled to form the carriage. As shown in the cross-sectional views of handle 100 in Figures 8 and 9, the carriage can have a right flexure rack half 530 and a left flexure rack half 540 that are linearly translatable along longitudinal axis 111 within drive housing 410. Distally, the piston carriage can have a bolt with a right half 520 and a left half 521, at least one of which can have external male threads 522.

[0057] In one embodiment, the threads 522 of the right flexure rack 530 of the piston carriage 510 are engaged with the helical drive threads 316 of the barrel nut 310. When the right flexure rack 530 and the left flexure rack 540 are constrained from rotating within the drive housing, the drive threads of the barrel nut can act linearly on the right flexure rack threads 522. As illustrated in FIG. 9 , rotation of the articulation knob 210 and the barrel nut 310 about the longitudinal axis 111 can cause corresponding linear translation of the right flexure rack 530 relative to the left flexure rack 540 within the drive housing 410 by driving the external threads 522 of the right flexure rack.

[0058] This rotation of articulation knob 210 and the resulting relative translation between the right and left halves 530, 540 of piston carriage 510 can be the mechanism for actuation of the aforementioned control member (not shown). Actuation of the control member can occur, for example, by tensioning a wire or compressing a toggle element.

[0059] The control members extend through the catheter shaft 27 and can cause deflection of the distal catheter tip 50. For example, proximal translation of the right flexure rack 530 relative to the left flexure rack 540 can tension a control wire or cable coupled to the distal end of the catheter, causing the steerable tip to angularly deflect in a first direction (relative to a start or neutral position). Similarly, distal translation of the right flexure rack 530 relative to the left flexure rack 540 can tension a second control wire or cable, causing the steerable tip to angularly deflect in a second direction opposite the first direction.

[0060] FIG. 10 shows the lower half 430 of the drive housing 410 in which the piston carriage 510 is disposed. Depending on the configuration, there are multiple ways to configure the relative motion of the right flexure rack 530 and left flexure rack 540 of the piston carriage 510 to provide separate and distinct tension forces to the aforementioned control members (not shown). In one configuration, the control wires may be directly coupled to the opposing halves of the piston carriage 510. In an alternative configuration, one of the wires may be directly coupled to the piston carriage, while the other wire is indirectly coupled to the piston carriage through a direction-reversing element, such as a pin or pulley (not shown). In this way, both wires are held taut, and relative motion of the right flexure rack 530 relative to the left flexure rack 540 in one direction applies tension to one of the control wires, while relative motion in the opposite direction applies tension to the other control wire. Equal and opposite translational motion between right flexure rack 530 and left flexure rack 540 may be maintained through the use of pinion gear 412 coupled to flexure rack teeth 541, as shown in cross section in FIG.

[0061] The coupling between the control member and the halves of the piston carriage 510 allows for relative motion to actuate the control member. In this sense, "direct coupling" means that the control wire forms an operative pair with one of the flexure racks, but is not necessarily attached to or integral with one of the flexure racks. "Indirect coupling" can mean that the wire forms an operative pair with (but is also not necessarily attached to) one of the flexure racks only after passing through an intermediate element, such as a pulley. The wire may be maintained within a sheath along most of its length, or with one or more strain relief methods employed to ensure that it is not subjected to excessive angulation or stress when coupled to the piston carriage 510.

[0062] Separate views of the right flexure rack 530 and the left flexure rack 540 are shown in FIGS. 12a and 12b, respectively. When mated together, the right drive bolt half 520 of the right flexure rack 530 and the left drive bolt half 521 of the left flexure rack 540 can form a cylindrical internal cavity 512 for a catheter sheath to extend through. From the cross-sectional view of FIG. 11, it can be seen that the pinion 412 can ensure no relative slippage between the right flexure rack 530 and the left flexure rack 540 by simultaneously engaging corresponding internal teeth 541 of both flexure racks. By metering the relative translation of the right and left flexure racks, the pinion teeth provide consistent and repeatable relative deflections for incremental rotations of the articulation knob 210. These deflections can be transmitted to a control member in the handle. A particular amount of angular rotation of articulation knob 210 can correspond to a particular amount of linear translation of right deflection rack 530 and therefore induce a particular angular deflection of catheter steerable tip 50. Pinion rotation ensures that tip deflection occurs in a smooth and reliable manner so that an experienced physician can comfortably operate and manipulate the catheter with the control handle without needing a visual reference check of the handle's orientation.

[0063] An exemplary exterior configuration of the lower half 430 of the drive housing 410 is illustrated in FIG. 13 . At least a portion of the lower drive housing half 430 can have longitudinal grooves or rails 436 formed therein that form tracks for guiding flexure of the right flexure rack 530 and the left flexure rack 540 of the piston carriage 510 and act as anti-rotation features therefor. The rails 436 can react to rotational torque generated from rotation of the articulation knob 210 so that movement of the flexure racks is linear along the longitudinal axis 111 of the handle. The lower drive housing half 430 can also have a pinion hub 432 to provide spindle location for the pinion 412. Additionally, a distally facing feature molded into the lower drive housing half 430 can form an end or physical stop 438 for proximal translation of the flexure racks 530, 540. Alternatively, length-adjustable physical stops can be installed to define the extreme range of travel of the flexure rack. The length can be adjustable by screws or through the use of shims. Any method, such as adhesive or a press fit, can be used to engage the physical stops with the rails 436 of the drive housing 410.

[0064] The linear displacement of the drive housing 410 itself can be controlled through the axial placement of a circumferential groove or thrust slot 434. The thrust slot can be sized to receive the collar 314 of the barrel nut 310 to provide transmission of the pushing / pulling force the user imparts to the knob 210 to the drive housing. Because the barrel nut 310 is of a fixed length, the longitudinal placement of the thrust slot can 434 can define the range of linear movement imparted to the articulation knob. For example, a more proximally located thrust slot 434 will place the barrel nut 310 closer to the proximal end 112 of the handle 100. This location allows for a greater length of travel for the drive housing 410 within the outer housing 110.

[0065] Representative illustrations of the articulation knob of the present design and its various features are shown in Figures 14a-c. The knob can be cylindrical or similarly shaped and can have raised, overmolded, or other contoured features on the exterior surface to provide a more secure grip with the thumb, or thumb and index finger, of the user's working hand. The knob 210 can be tapered at the distal end 113 for passage of the catheter shaft 27. The distal end 113 can be chamfered with a gentle edge radius to allow free translation and rotation of the knob while avoiding sharp corners that could twist or damage the shaft.

[0066] 14b and 14c, the interior of articulation knob 210 can have a knob hub 212 for interfacing with a barrel nut 310 or other component feature of handle 100. Rotation can be transferred from the knob to the barrel nut through one or more keyways 214 formed within the hub. The keyways can be tapered or square, and the length can vary based on the size of the hub and the torsional load to be transferred. Alternatively, knob hub 212 can be shrink-fit onto barrel nut 310.

[0067] 15 and 16 show perspective and cross-sectional views, respectively, of barrel nut 310. The barrel nut can be substantially tubular in shape and can have a distally reduced diameter for insertion into the interior of articulation knob 210. In one embodiment, barrel nut 310 has one or more outwardly extending keys 312 that cooperatively engage or fit within corresponding keyways 214 (see FIG. 14c ) of the articulation knob. Keys 312 can function as a retention mechanism to prevent relative angular motion and transfer torque between knob 210 and barrel nut 310. This couples barrel nut 310 to rotate with articulation knob 210. Thus, rotational and translational motion of knob 210 is transferred to barrel nut 310, and they can move as a single unit relative to outer housing 110 of handle 100.

[0068] Axially adjacent the proximal end 318 of barrel nut 310, thrust collar 314 mates with a circumferential slot 434 in the drive housing to transfer pushing / pulling forces between the knob and drive housing 410. Slot 434 and thrust collar 314 can lock the longitudinal translation of the articulation knob and drive housing while allowing free rotational movement of the knob.

[0069] Female drive spline threads 316 may be machined or formed into the interior surface of the barrel nut, as illustrated in the cross-sectional view of FIG. 16. When torque is transmitted from articulation knob 210 to barrel nut 310, spline threads 316 may engage drive bolt threads 522 on right flexure rack 530 or left flexure rack 540 of piston carriage 510 (see FIG. 10). Rotation of the spline thus drives relative linear displacement between right flexure rack 530 and left flexure rack 540.

[0070] Features may be formed or machined into the surface of knob hub 212 or barrel nut 310 to act as set points that are rotated to maintain a particular tip deflection corresponding to a particular amount of angular rotation as various clocking positions are engaged for articulation knob 210. These features, such as detents or axial relief notches or grooves, can selectively maintain a particular tip deflection and give the knob the ability to "click in," providing tactile feedback to the user when a particular discrete engagement point is reached.

[0071] Alternatively, a friction device such as a rubber grommet or O-ring may be used between barrel nut 310 and the inner surface of drive housing 410 to create a friction lock that increases rotational resistance and maintains articulation knob 210 in a desired rotational position relative to the shaft.

[0072] Many expandable elements utilized with steerable catheters require a separate actuation mechanism in addition to steering the control handle to actuate the expandable element between a collapsed delivery state within the delivery catheter or sheath and an expanded, deployed state at the target site. For example, the expandable ablation balloon 610 shown in FIG. 6 can be expanded to a deployed configuration to provide atraumatic alignment with the ostium of a pulmonary vein. An advantage of this design is that it combines balloon expansion and retraction with the steerable functionality of the control handle to control the radial size of the balloon without any additional auxiliary mechanisms.

[0073] To deliver the steerable catheter tip 50 with the expandable element or balloon 610 within a guide sheath or outer catheter to a target location, it may be necessary to first collapse the balloon 610 and any associated leads and electrodes to a smaller diameter. The collapsed diameter can conform to a common guide sheath of a specific inner diameter, such as 13.8F. The displacement function of the articulation knob 210 of the handle 100 can articulate the advancement mechanism 620, which can lengthen from its nominal, approximately spherical shape ( FIG. 17 b) to an elongated, football-like profile with a smaller radial size for delivery ( FIG. 17 a). This movement can be similar to a tubular bellows or expansion joint, whose diameter changes with the axial position of the corresponding end. In some cases, the advancement mechanism 620 can be glued to the distal end of the balloon 614 using adhesive or other suitable means. Alternatively, the distal end of the balloon 614 can be glued to a rigid extension collar 630 to provide a sturdy attachment point.

[0074] The advancement mechanism 620 can extend proximally the length of the catheter shaft 27 so as to be coupled to the drive housing 410 in the control handle 100. In this manner, the advancement mechanism 620 can telescopically operate with the catheter shaft 27 to provide the elongation necessary to move the distal end 614 of the balloon 610 distally and reduce the outer diameter of the balloon. The advancement mechanism can be a tube with an internal lumen 622 for guidewires and other small auxiliary devices, and a conduit to direct irrigation for cooling and prevention of blood clotting.

[0075] The advancement mechanism 620 can have sufficient column stiffness to smoothly transfer thrust loads to translate the distal end of the expandable member, while also having sufficient lateral flexibility for delivery to the target site through tortuous blood vessels. In one embodiment, the advancement mechanism can be constructed from a sturdy, chemically resistant polymeric material, such as flexible polyimide tubing. Alternatively, the advancement mechanism can be a tubular, coiled, or looped support structure covered with an outer jacket.

[0076] In one embodiment, the control elements for deflection of the distal tip can be a pair of control wires 29 that extend substantially along the length of the catheter shaft 27, as shown in Figure 18 and the corresponding close-up representation in Figure 19. As previously discussed, the wires 29 can be coupled proximally to right and left flexure racks 530, 540 of the piston carriage 510 within the drive housing 410. The control wires can be constructed of steel or a high molecular weight polymer with sufficient tensile strength to cause tip deflection when the articulation knob 210 is rotated about the handle axis 111.

[0077] Wires 29 may be bonded or crimped distally on either side of the cross or T-shaped member 28. Clockwise rotation of the articulation knob can tension a wire bonded to one side of the T-shaped member, causing the catheter sheath or shaft 27 to deflect in a first direction relative to a nominal starting position. Similarly, counterclockwise rotation of the knob can tension a second wire secured to the opposite side of the T-shaped member, causing the shaft to deflect in a second direction. A direction-reversing element, such as a pin or pulley, can be used in the handle to ensure both wires 29 remain tensioned regardless of which direction the knob is rotated.

[0078] 20a-20f are diagrammatic representations of a sequence of use for a control handle 100 of a steerable catheter having a distal expandable element as described herein. For illustrative purposes, the catheter is assumed to be configured with an expandable element such as an ablation balloon 610 as shown in FIGS. 17a and 17b. The figures feature a cross-sectional central portion of the outer housing 110 so that the movement of the components within the housing as a result of manipulation of the articulation knob 210 can be seen.

[0079] 20a shows the articulation knob 210, drive housing 410, and piston carriage 510 of the control handle 100 at the proximal-most limit of longitudinal travel. The right flexure rack 530 and left flexure rack 540 of the piston carriage 510 are axially aligned, and the drive bolt threads 522 of the right drive bolt half 520 are engaged with the internal threads of the barrel nut 310. The piston carriage can move along one or more extension pistons 542 within the housing. Arrows superimposed on the articulation knob indicate the directions of rotation and translation available for articulating the knob.

[0080] Distal linear translation of articulation knob 210 from the nominal start position of FIG. 20a is shown in FIG. 20b. Thrust collar 314 of barrel nut 310 can pull drive housing 410 distally such that right flexure rack 530 and left flexure rack 540 of piston carriage 510 also translate distally along one or more extension pistons 542. Distal translation of knob 210 can push advancement mechanism 620 and extension collar 630 downstream to reduce the radial size of balloon 610 (see FIG. 17a). Full distal extension of the knob can fully collapse the balloon for repositioning during a procedure or for resheathing for retraction from the patient.

[0081] Referring to FIG. 20c, the applied distal translation of articulation knob 210 can be maintained while independently rotating the knob about longitudinal axis 111. Rotation of knob 210 can also rotate barrel nut 310. The helical internal threads 316 of barrel nut 310 can engage and drive the external threads 522 on the right half of drive bolt 520, splitting and axially translating right and left flexure racks 530, 540. Right flexure rack 530 can be displaced proximally along expansion piston 542, as shown in FIG. 20d. Engagement of teeth 541 on both right and left flexure racks 530, 540 with pinion 412 can also cause corresponding distal translation of the left flexure rack. Control members or wires (not shown) connected to one or both of the right and left flexure racks can be tensioned by these translations, deflecting catheter shaft 27.

[0082] Figure 20e illustrates that the deflection exhibited by catheter shaft 27 can be maintained, as demonstrated by the continued axial misalignment of right and left flexure racks 530, 540, while the user translates articulation knob 210 proximally along longitudinal axis 111. Conversely to Figure 20b, proximal movement of the knob can pull advancement mechanism 620 and extension collar 630 proximally, increasing the radial size of the balloon (see Figure 17b) to begin or resume the ablation procedure.

[0083] When articulation knob 210 is manipulated to return to its original longitudinal starting position, the knob can be rotated in the opposite direction of the rotation applied in FIG. 20c. Rotation of the barrel nut can drive threads 522 of right flexure rack 530 to translate distally, rotating pinion 412 to return right flexure rack 530 and left flexure rack 540 of piston carriage 510 to longitudinal alignment, as shown in FIG. 20f. Rotation of the knob can also return catheter shaft 27 to its initial, undeflected state.

[0084] Alternatively, the linear translation of articulation knob 210 and the induced motion of right retraction rack 530 and left retraction rack 540 can be coupled to deflection of the catheter tip, in which case rotation of articulation knob 210 can be used to vary the radial size of the expandable element or balloon, or to activate and operate various diagnostic capabilities of the catheter.

[0085] The multi-electrode balloon 610 of FIG. 6 is shown in FIG. 21 performing an ablation treatment of a pulmonary vein 70 in the left atrium. The length of the electrodes 616 of the ablation balloon 610 can be selected to ensure contact with the target tissue wall 72 even when the catheter is not perfectly aligned with the ostium of the pulmonary vein 70. The multiple electrodes 616 can be positioned independently of one another. Functionally, this allows the amount of power delivered to each electrode to be separately controlled to improve the safety and quality of the lesions formed in the ablation zone 56. Leads from an energy source (not shown) can be shorted to the pads of the electrodes 616, where changes in voltage can be correlated to changes in temperature as the electrodes heat up via conductive heat transfer from the ablated tissue.

[0086] When deployed from the sheath or outer catheter 10, the balloon 610 can be expanded from its collapsed state to isolate the vein. Similar to the process previously described, the balloon can be expanded by translating the articulation knob 210 proximally to pull the advancement mechanism 620 and extension collar 630 at the balloon's distal end 614 toward its proximal end 612, increasing its diameter.

[0087] Ablation catheters with multi-function tips are often fitted with a miniature pump for irrigation. For example, heparinized normal saline from the pump can be delivered distally to the electrode pad 616 through a Luer fitting 40 in the handle 100, often with holes drilled to allow fluid flow from the interior to the exterior of the balloon 610. The irrigation flow 58 can enable tip functions such as balloon inflation and cooling of the ablation electrode 616 and the ablation-tissue interface at the ablation zone 56. The flow 58 also functions to move blood away from the treatment site to maintain uninterrupted access.

[0088] The lumen 622 of the advancement mechanism 620 may also be used for distal irrigation, contrast, or deployment of auxiliary devices. Such devices may include a guidewire or small diameter diagnostic catheter 60, as seen in FIGURE 21. The diagnostic catheter may be a hypotube structure that may be deployed from the lumen 622 into a distal hoop shape for stimulation and recording of signals within the atria of the heart.

[0089] 22 and 23 are each flow diagrams including method steps for performing a medical procedure using the control handles disclosed herein. The method steps may be implemented by any of the devices and / or apparatus described herein and may be performed in an order other than that listed.

[0090] Referring to method 2200 outlined in FIG. 22 , step 2210 involves introducing a catheter for an intracardiac procedure. The catheter can include a catheter shaft having a proximal region and a deflectable distal region, an expandable element or member proximate the distal end of the shaft, and a control handle. The control handle can include an outer shell, a drive assembly, and a distal knob assembly having an internal drive spline and capable of linear translation along and rotation about the longitudinal axis of the handle. Step 2220 involves movably disposing the drive assembly within the outer shell of the control handle such that the drive assembly can translate along the longitudinal axis of the handle. The drive assembly can include an inner housing, a distal drive bolt having external threads, and a split piston carriage.

[0091] At step 2230, the split piston carriage is engaged with the helical threads of the internal drive spline of the knob assembly such that at least a portion of the split piston carriage is movable relative to the drive housing. When engaged, rotation of the knob assembly results in linear translation of at least a portion of the piston carriage within the drive housing. At step 2240, the control handle is configured for single-handed operation, with the thumb and index finger capable of operating all possible functions of the handle without the need for visual reference.

[0092] Manipulation of the distal knob assembly of the control handle can actuate various functions of the steerable tip of the catheter. Step 2250 can involve configuring the distal knob assembly to longitudinally translate the drive assembly relative to the outer shell. This translation can actuate a change in the radial size of the expandable element at the distal end of the steerable catheter. Distal translation of the drive assembly can decrease the radial size, while proximal movement of the drive assembly can increase the radial size.

[0093] 22 and 2310, rotation of the distal knob assembly can angularly deflect the distal region of the catheter. In one embodiment, the deflection can be planar, such that clockwise rotation of the knob deflects the distal region in a first direction and counterclockwise rotation causes deflection in a second direction opposite the first direction.

[0094] Further referring to FIG. 23 , in step 2320, the linear translation of the drive assembly and distal knob assembly can be coupled independently of the rotation of the knob assembly. A particular linear translation of the drive assembly and knob assembly can then be maintained while rotating the knob to deflect and steer the distal region of the catheter. In step 2330, the distal knob assembly of the control handle can have limited overall translational and rotational movement. For example, a physical stop feature can be molded into the outer shell of the handle or a shim can be provided to limit the total proximal and distal travel available to the drive housing. The length of the externally threaded portion of the flexure rack can be selected to stop further knob rotation in the clockwise or counterclockwise direction, setting a design limit for catheter tip deflection. A groove or relief is configured to engage the knob assembly at various distances of translational movement so that the intermediate radial size of the expandable element can be affected. The intermediate size can be advantageous by allowing the expandable element to be sized to fit various features or geometries of the target vasculature. Those skilled in the art will appreciate other advantages of being able to set travel limits or adjust the size of the expandable element at the catheter tip in situ.

[0095] Step 2340 involves linearly translating the distal knob assembly to increase the radial size of the expandable element. This process can be useful for performing diagnostic, therapeutic, and / or other procedures. For example, without limitation, a cardiac ablation procedure can involve contacting tissue surrounding the ostium of a pulmonary vein with one or more electrodes at the catheter tip for delivery of energy. Energy from the one or more electrodes can then be used to ablate tissue and form scar tissue lesions in the treatment of PAF or other cardiac arrhythmias in step 2350. In other examples, energy can be used for imaging or mapping procedures.

[0096] Once the procedure is complete, it is often necessary to retract the deployed device into the sheath or outer catheter so that it can be safely removed from the patient. In step 2360, the distal knob assembly is linearly translated to reduce the radial size of the expandable element so that it can be retracted into the inner diameter of the sheath or outer catheter.

[0097] The present invention is not necessarily limited to the examples described, which may vary in configuration and details. The terms "distal" and "proximal" are used throughout the foregoing description and are intended to refer to a location and direction relative to the treating physician. Thus, "distal" or "distally" refers to a location away from or a direction away from the physician. Similarly, "proximal" or "proximally" refers to a location closer to or a direction toward the physician. Furthermore, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0098] As used herein, the terms "about" or "approximately" in connection with any numerical value or range of values ​​indicates a dimensional tolerance appropriate for allowing a portion of a component or a collection of components to function for its intended purpose as described herein. More specifically, "about" or "approximately" may refer to a range of values ​​of ±20% of the recited value; for example, "about 90%" may refer to a range of values ​​of 71% to 99%.

[0099] In describing exemplary embodiments, technical terminology is employed for the sake of clarity. Each term is intended to have its broadest meaning as understood by one of ordinary skill in the art and is intended to include all technical equivalents that operate in a similar manner to accomplish a similar purpose without departing from the scope and spirit of the present invention. It should also be understood that a reference to one or more steps of a method does not exclude the presence of additional method steps or intervening method steps between those explicitly identified steps. Some steps of a method may be performed in an order different from that described herein without departing from the scope of the disclosed technology. Similarly, it should also be understood that a reference to one or more components in a device or system does not exclude the presence of additional components or intervening components between those explicitly identified components. For the sake of clarity and conciseness, not all possible combinations have been listed; such modifications will often be apparent to those skilled in the art and are intended to be within the scope of the following claims.

[0100] [Embodiment] (1) A control handle for a catheter having a steerable tip, said control handle comprising: a tubular outer housing defining a longitudinal axis, a proximal end, and a distal end; an articulation knob adjacent the distal end of the tubular outer housing, the articulation knob rotatable about and linearly displaceable along the longitudinal axis of the tubular outer housing; a drive housing movably disposed within the tubular outer housing and coupled to the articulation knob, the drive housing comprising a split piston carriage and a pinion, the articulation knob comprising: imparting a first linear displacement to the drive housing when the articulation knob is rotated clockwise about the longitudinal axis of the tubular outer housing; when the articulation knob is rotated counterclockwise about the longitudinal axis of the tubular outer housing, it imparts a second linear displacement to the drive housing opposite to the first linear displacement; and a control handle configured to impart a third linear displacement to the drive housing when the articulation knob is linearly displaced a distance parallel to the longitudinal axis, the third linear displacement being configured to change the radial size of an expandable element on the distal end of the steerable catheter. (2) A control handle as described in embodiment 1, further comprising an advancement mechanism mechanically coupled distally to the expandable element and proximally to the drive housing. (3) A control handle as described in embodiment 2, wherein linear translation of the advancement mechanism causes a change in the radial size of the expandable element. (4) A control handle as described in embodiment 1, wherein the first linear displacement of the drive housing is configured to actuate a first control member of the steerable tip, and the second linear displacement of the drive housing is configured to actuate a second control member of the steerable tip. (5) A control handle as described in embodiment 4, wherein each of the first control member and the second control member comprises a control wire.

[0101] (6) The control handle of embodiment 1, wherein the expandable element comprises a balloon. (7) A control handle as described in embodiment 6, wherein the balloon is provided with a plurality of independently controlled electrodes equally spaced around the circumference of the balloon. (8) A control handle as described in embodiment 2, wherein the advancement mechanism comprises an elongated tubular member having an internal hollow lumen. (9) A control handle as described in embodiment 1, wherein the articulation knob further comprises a hub, a proximal end, a distal opening, and at least one keyway. (10) The control handle of embodiment 9, further comprising a barrel nut coupled to the articulation knob and rotatable about the longitudinal axis of the tubular outer housing, the barrel nut comprising one or more keys disposed at one end, a thrust collar at the other end, and a drive spline disposed inside the barrel nut.

[0102] (11) The control handle of claim 10, wherein the barrel nut is longitudinally coupled to the drive housing by the thrust collar, the thrust collar configured to linearly displace the drive housing when the articulation knob is linearly displaced about a longitudinal axis. (12) The control handle of claim 10, wherein the barrel nut is configured to be rotationally coupled to the articulation knob by the one or more keys. (13) The control handle of claim 10, wherein the drive spline is configured to engage threads of the split piston carriage to displace at least a portion of the piston carriage along a linear path when the articulation knob is rotated. (14) The control handle of embodiment 1, wherein the split piston carriage of the drive housing includes a drive bolt, a right flexure rack, and a left flexure rack. (15) A control handle as described in embodiment 14, wherein clockwise rotation of the articulation knob results in linear translation of the right flexure rack relative to the left flexure rack in a first direction.

[0103] (16) A control handle as described in embodiment 15, wherein counterclockwise rotation of the articulation knob results in linear translation of the right flexure rack relative to the left flexure rack in a second direction opposite the first direction. (17) The control handle of claim 15, further comprising a pinion coupled to the right flexure rack and the left flexure rack, the pinion rotating when the right flexure rack translates linearly relative to the left flexure rack. (18) The control handle of embodiment 1, wherein the articulation knob is linearly displaceable independently of being rotated about the longitudinal axis. (19) The control handle of embodiment 8, wherein the elongated tubular member of the advancement mechanism comprises a flexible polyimide tube. (20) The control handle of embodiment 1, further comprising a Luer fitting configured to receive fluid injection.

Claims

1. 1. A control handle for a catheter having a steerable tip, said control handle comprising: a tubular outer housing defining a longitudinal axis, a proximal end, and a distal end; an articulation knob adjacent the distal end of the tubular outer housing, the articulation knob rotatable about and linearly displaceable along the longitudinal axis of the tubular outer housing; a drive housing movably disposed within the tubular outer housing and coupled to the articulation knob, the drive housing comprising a split piston carriage and a pinion, the articulation knob comprising: imparting a first linear displacement to the drive housing when the articulation knob is rotated clockwise about the longitudinal axis of the tubular outer housing; when the articulation knob is rotated counterclockwise about the longitudinal axis of the tubular outer housing, it imparts a second linear displacement to the drive housing opposite to the first linear displacement; and the articulation knob, when linearly displaced a distance parallel to the longitudinal axis, is configured to impart a third linear displacement to the drive housing configured to vary a radial size of an expandable element on the distal end of the steerable catheter; the articulation knob further comprises a hub, a proximal end, a distal opening, and at least one keyway; the control handle further comprises a barrel nut coupled to the articulation knob and rotatable about the longitudinal axis of the tubular outer housing, the barrel nut comprising one or more keys disposed at one end, a thrust collar at the other end, and a drive spline disposed inside the barrel nut; the barrel nut is longitudinally coupled to the drive housing by the thrust collar, the thrust collar configured to linearly displace the drive housing when the articulation knob is linearly displaced about a longitudinal axis. Control handle.

2. The control handle of claim 1 , further comprising an advancement mechanism mechanically coupled distally to the expandable element and proximally to the drive housing.

3. The control handle of claim 2 , wherein linear translation in the advancement mechanism causes a change in the radial size of the expandable element.

4. 2. The control handle of claim 1, wherein the first linear displacement of the drive housing is configured to actuate a first control member of the steerable tip and the second linear displacement of the drive housing is configured to actuate a second control member of the steerable tip.

5. The control handle of claim 4 , wherein the first control member and the second control member each comprise a control wire.

6. The control handle of claim 1 , wherein the expandable element comprises a balloon.

7. The control handle of claim 6, wherein the balloon comprises a plurality of independently controlled electrodes equally spaced around the circumference of the balloon.

8. The control handle of claim 2 , wherein the advancement mechanism comprises an elongated tubular member having an internal hollow lumen.

9. The control handle of claim 1 , wherein the barrel nut is configured to be rotationally coupled to the articulation knob by the one or more keys.

10. 2. The control handle of claim 1, wherein the drive splines are configured to engage threads of the split piston carriage to displace at least a portion of the split piston carriage along a linear path when the articulation knob is rotated.

11. The control handle of claim 1 , wherein the split piston carriage of the drive housing comprises a drive bolt, a right flexure rack, and a left flexure rack.

12. The control handle of claim 11 , wherein clockwise rotation of the articulation knob effects linear translation of the right flexure rack relative to the left flexure rack in a first direction.

13. The control handle of claim 12 , wherein counterclockwise rotation of the articulation knob effects linear translation of the right flexure rack relative to the left flexure rack in a second direction opposite the first direction.

14. The control handle of claim 12 , further comprising a pinion coupled to the right flexure rack and the left flexure rack, the pinion rotating as the right flexure rack translates linearly relative to the left flexure rack.

15. The control handle of claim 1 , wherein the articulation knob is linearly displaceable independently of being rotated about the longitudinal axis.

16. The control handle of claim 8 , wherein the elongated tubular member of the advancement mechanism comprises a flexible polyimide tube.

17. The control handle of claim 1 , further comprising a luer fitting configured to receive a fluid injection.

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