Patent Publication Number: US-2022218306-A1

Title: Handle assembly for transesophageal echocardiography

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to the imaging of the organs of a patient using transesophageal echocardiography (TEE), and the control of the TEE probe via pull cables located in its handle. For example, some embodiments of the present disclosure are suited for controlling the position, orientation, and flexion of a TEE gastroscope probe. 
     BACKGROUND 
     Observing the condition and function of a patient&#39;s heart can be a difficult and dangerous procedure. Echocardiography can mitigate risk of injury to the patient by using ultrasonic imaging techniques. In an echocardiogram, a physician uses an ultrasonic probe comprising one or more ultrasonic transducers to obtain images of various angles of the patient&#39;s heart. The ultrasonic transducers emit ultrasonic energy in the form of ultrasonic waves to create an image of the heart. Ultrasonic waves are partially reflected by discontinuities arising from tissue structures, red blood cells, and other features of interest. Echoes, or the reflected ultrasonic waves, are received by the ultrasonic transducer and transmitted to a signal processor. The signal processor processes the received ultrasound echoes to produce an image of the heart near the location where the ultrasonic transducer is placed. 
     One common echocardiography procedure is a transthoracic echocardiogram (TTE), which involves placing an ultrasonic probe on the chest or abdomen of a patient to obtain images of various angles of the patient&#39;s heart. Although TTE is a relatively non-invasive procedure, the ultrasonic waves must travel through several layers of tissue and bone to reach the heart, and the echoes must travel back through the same tissue and bone to reach the ultrasonic transducer. These thick layers of tissue and bone can weaken the strength of the echoes and degrade the quality of the image obtained. 
     Transesophageal echocardiography (TEE) involves obtaining an ultrasonic image of the heart using a TEE probe positioned within the patient&#39;s esophagus. TEE probes also use ultrasonic waves to obtain an image of a patient&#39;s heart. Transesophageal echocardiography can be advantageous because the heart is located near the esophagus, which can result in higher quality images. To obtain an image using a TEE probe, a physician inserts a gastroscope including an ultrasonic transducer into the patient&#39;s esophagus and guides the ultrasonic transducer to an area near the heart. The physician manipulates a distal portion of the gastroscope within the patient&#39;s esophagus to guide the ultrasonic transducer into place, and to maintain contact with the esophagus wall to facilitate the transmission and reception of the ultrasonic waves. 
     It is to be appreciated that such commonly used TEE handles have numerous drawbacks, including cost, durability, reliability, ergonomics, electrical grounding, and otherwise. The handle portion of a conventional TEE probe comprises multiple complex machined parts and assemblies that may require highly precise manufacturing tolerances, expensive materials, and substantial assembly time and labor. For example, the brake assembly may include up to four separate pieces working in conjunction with one another. Articulation of current TEE probes involves a stainless steel pull wire system driven by a nested rack and pinion system made of hardened beryllium copper. These metal components may cause electrical isolation issues. Left/Right and Anterior/Posterior Control wheels are attached to respective pinion shafts and provide user inputs to drive the system. Pinions, racks, housings, and related components are all metallic, as are the outside user handles, and potentially the patient contact handles for the control housing. All internal structures are electrically grounded, while metal handles are electrically isolated from internal structures via a complicated set of static and dynamic overlapping isolating components that provide adequate electrical creepage and clearance throughout the entire range of positions the articulation mechanism can provide. Further isolation is achieved via a distal plastic isolation member attached to the main rack and pinion housing via a dovetail engagement. The distal isolator is prone to failure due to its complicated attachment to the metal housing. 
     SUMMARY 
     Disclosed is a transesophageal echocardiography (TEE) probe mid-handle assembly. The TEE probe mid-handle assembly includes improved and simplified components, and has particular, but not exclusive, utility for the control of TEE probes for imaging of the human heart. 
     Embodiments of the present disclosure provide an improved mid-handle assembly for a transesophageal echocardiography (TEE) probe for generating images of an organ that has improved cost and manufacturability properties. The TEE probe mid-handle assembly provides a non-metal design for TEE probe articulation that translates a user&#39;s turn of a control knob into linear articular pulls of the catheter. The assembly may include a molded plastic containment frame, which electrically isolates any internal components from metal exterior components, if present. The assembly may also include one or more floating drive shafts for translating knob rotation to pull elements, and one or more non-metallic pull elements in communication with the drive shaft or shafts. The TEE mid-handle assembly will accomplish TEE gastroscope articulation and electrical isolation from grounded structures in a more direct and reliable manner by eliminating the traditional rack and pinions and utilizing a nonmetallic method of translating rotational user control to linearly pull articulation control cables. In addition, a nonmetallic molded control knob, cam, and distal isolator may be employed to nest and capture a pair of articulation control shafts, which has the benefit of naturally isolating the articulation assembly from an external metallic handle, if present. 
     In an example, the TEE probe can include simplified mechanisms, such as friction belts, timing ladders, pulley cables, timing belts, and tape drives, that replace the rack and pinion system to couple the control knobs to the pull cables that steer the imaging element. In some embodiments, the brake assembly has been simplified and may be a monolithic brake switch (i.e., formed as a single piece). In some embodiments, machined metal components have been replaced with molded plastic components having less precise manufacturing tolerances and improved electrical isolation properties. In some embodiments, multi-part assemblies and enclosures have been replaced by assemblies with a smaller part count, fewer assembly steps, fewer failure points, lighter weight, and improved ease of operation. 
     In an exemplary embodiment, the transesophageal echocardiography (TEE) probe comprises a containment frame, a first control input located external to the containment frame, a first shaft located internal to the containment frame and coupled to the first control input, a first elongated flexible member comprising a first end and a second end, wherein the first elongated flexible member is wrapped around the first shaft, a first pull cable attachment coupled to the first end of the first elongated flexible member, a second pull cable attachment coupled to the second end of the first elongated flexible member, a first pull cable attached to the first pull cable attachment, and a second pull cable attached to the second pull cable attachment, wherein, when the first control input is actuated, the first shaft is rotated such that the first and second ends of the first elongated flexible member move linearly, causing one of the first or second pull cable to move in a first direction and causing the other of the first or second pull cable to move in an opposite, second direction, and wherein a distal portion of a gastroscope coupled to the first and second pull cables is flexed according to movements of the first and second pull cables. 
     In some embodiments, the TEE probe further comprises a second control input located external to the containment frame, a second shaft located internal to the containment frame and coupled to the second control input, a second elongated flexible member comprising a first end and a second end, wherein the second elongated flexible member is wrapped around the second shaft, a third pull cable attachment coupled to the first end of the second elongated flexible member, a fourth pull cable attachment coupled to the second end of the second elongated flexible member, a third pull cable attached to the third pull cable attachment, and a fourth pull cable attached to the fourth pull cable attachment, wherein, when the second control input is rotated, the second shaft is rotated such that the first and second ends of the second elongated flexible member move linearly, causing one of the third or fourth pull cable to move in the first direction, and causing the other of the third or fourth pull cable to move in the opposite, second direction, and wherein the distal portion of the gastroscope coupled to the third and fourth pull cables is flexed according to movements of the third and fourth pull cables. 
     In some embodiments, the TEE probe further comprises a monolithic brake switch that, when rotated into a first position, applies a resistance to rotation of the first and second shafts and, when rotated into a second position, permits the first and second shafts to rotate without the resistance. In some embodiments, at least one of the control inputs, shafts, elongated flexible members, brake switch, or containment frame is nonconductive. In some, at least one of the control inputs, shafts, brake switch, or containment frame is made of molded plastic. In some embodiments, the first and second elongated flexible members are made of elastomeric compounds molded over nylon reinforcement members. In some embodiments, the first control input directs anterior and posterior flexion of the distal portion of the gastroscope, and the second control input directs left/right flexion of the gastroscope. In some embodiments, the first and second elongated flexible members are friction belts. In some embodiments, the first and second shafts comprise gears or pinions, and the first and second elongated flexible members are timing ladder belts interfacing with the gears or pinions. In some embodiments, the first shaft and second shaft each comprise a socket, and wherein the first elongated flexible member is a pulley cable anchored to the first shaft by a swaged ball or screw attachment fitting into the socket in the first shaft, and wherein the second elongated flexible member is a pulley cable anchored to the second shaft by a swaged ball or screw attachment fitting into the socket in the second shaft. In some embodiments, the first and second shafts comprise gears or pinions, and wherein the first and second elongated flexible members are timing belts interfacing with the gears or pinions. In some embodiments, the first and second shafts comprise gears or pinions, and the first and second elongated flexible members are drive tapes interfacing with the gears or pinions. 
     In some embodiments the pull cable attachments are formed directly into the elongated flexible members. In some embodiments, the pull cable attachments each include a threaded tensioning mechanism. In some embodiments, the TEE probe further comprises an outer handle casing. In some embodiments wherein the first and second shafts are coaxial. In some embodiments, the TEE hand further comprises a floating, nonrotating interior shaft affixed to the containment frame and situated between the first and second shafts to limit cross-coupling of motion between the first and second shafts. 
     In an exemplary embodiment, a method for transesophageal echocardiography (TEE) comprises controlling flexion of a distal portion of a gastroscope of a TEE probe, based on actuation of a control input of the TEE probe, wherein the TEE probe comprises the gastroscope, a containment frame, a handle assembly coupled to the gastroscope and comprising the control input, a shaft coupled to the control input, an elongated flexible member comprising a first end and a second end, the elongated flexible member wrapped around the shaft, a first pull cable attachment attached to the first end of the elongated flexible member, and a second pull cable attachment attached to the second end of the first elongated flexible member, a first pull cable attached to the first pull cable attachment and the distal portion of the gastroscope; and a second pull cable attached to the second pull cable attachment and the distal portion of the gastroscope, wherein controlling flexion includes: rotating the shaft coupled to the control input, in response to actuation of the control input, linearly moving, in response rotating the shaft, the first pull cable attachment and the second pull cable attachment, linearly moving, in response to corresponding movements of the first pull cable attachment and the second pull cable attachment, the first pull cable and the second pull cable to cause the flexion of the distal portion of the gastroscope, and applying a resistance to rotation of the shaft, in response to rotation of a brake switch of the handle assembly into a first position, and permitting rotation of the shaft without the resistance, in response to the rotation of the brake switch to a second position. In some embodiments, at least one of the brake switch, the control input, the shaft, the elongated flexible member, the containment frame, the first pull cable attachment, or the second pull cable attachment are made of molded plastic. 
     In an exemplary embodiment, a TEE probe comprises a gastroscope and a handle assembly coupled to the gastroscope and comprising a control input, a shaft coupled to the control input, an elongated flexible member wrapped around the shaft, the elongated flexible member comprising a first end and an opposite, second end, wherein the elongated flexible member comprises at least one of a friction belt, a timing ladder, a pulley cable, a timing belt, or a drive tape, a first pull cable attachment and a second pull cable attachment respectively attached to the first end and the second end of the elongated flexible member, and a monolithic brake switch configured to selectively apply resistance to rotation of the shaft, a first pull cable attached to the first pull cable attachment and a distal portion of the gastroscope, and a second pull cable attached to the second pull cable attachment and the distal portion of the gastroscope for each elongated flexible member, wherein, when the control input is actuated, the shaft rotates such that the first and second pull cable attachments move linearly and such that the first and second pull cables correspondingly move linearly to flex the distal portion of the gastroscope, and wherein the monolithic brake switch, when rotated into a first position, applies the resistance to the rotation of the shaft and, when rotated into a second position, permits the shaft to rotate without the resistance, and wherein at least one of the brake switch, the control input, the shaft, the elongated flexible member, the first pull cable attachment, or the second pull cable attachment are made of molded plastic. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. A more extensive presentation of features, details, utilities, and advantages of the TEE probe handle assembly, as defined in the claims, is provided in the following written description of various embodiments of the disclosure and illustrated in the accompanying drawings. 
     Additional aspects, features, and advantages of the present disclosure will become apparent from the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments of the present disclosure will be described with reference to the accompanying drawings, of which: 
         FIG. 1  depicts a diagrammatic view of a transesophageal echocardiography (TEE) ultrasonic imaging system, according to at least one embodiment of the present disclosure. 
         FIG. 2  is a side elevation view of a TEE probe, according to at least one embodiment of the present disclosure. 
         FIG. 3  is a diagrammatic view of the handle portion of the TEE probe of  FIG. 2 , according to at least one embodiment of the present disclosure. 
         FIG. 4  depicts a translucent isometric view of the interior mechanism of a conventional TEE mid-handle assembly. 
         FIG. 5A  is a side elevation view of a lateral side of a distal portion of a TEE probe, illustrating anterior and posterior flexion of the distal portion, according to at least one embodiment of the present disclosure. 
         FIG. 5B  is a side elevation view of a front side of the distal portion of the TEE probe of  FIG. 5A , illustrating left and right flexion of the distal portion, according to at least one embodiment of the present disclosure. 
         FIG. 5C  is a side elevation view of the front side of the distal portion of the TEE probe of  FIG. 5A , illustrating counterclockwise rotation, clockwise rotation, advanced and withdrawn positioning of the distal portion, according to at least one embodiment of the present disclosure. 
         FIG. 5D  is an isometric view of the distal portion of the TEE probe of  FIG. 5A , illustrating increasing and decreasing multi-plane angles of an ultrasonic transducer, according to at least one embodiment of the present disclosure. 
         FIG. 6  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates friction belts according to at least one embodiment of the present disclosure. 
         FIG. 7  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates friction belts according to at least one embodiment of the present disclosure. 
         FIG. 8  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates timing ladders according to at least one embodiment of the present disclosure. 
         FIG. 9  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates pulley cables according to at least one embodiment of the present disclosure. 
         FIG. 10  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates pulley cables according to at least one embodiment of the present disclosure. 
         FIG. 11  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates pulley cables according to at least one embodiment of the present disclosure. 
         FIG. 12  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates pulley cables according to at least one embodiment of the present disclosure. 
         FIG. 13  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates timing belts according to at least one embodiment of the present disclosure. 
         FIG. 14 a    is an isometric view of a portion of the mid-handle mechanism of a conventional TEE probe that uses a rack and pinion mechanism to transfer motion from the control wheels to the pull cables. 
         FIG. 14 b    is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates timing belts according to at least one embodiment of the present disclosure. 
         FIG. 15  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates timing belts according to at least one embodiment of the present disclosure. 
         FIG. 16  is an isometric view of a tape drive according to at least one embodiment of the present disclosure. 
         FIG. 17  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates timing belts according to at least one embodiment of the present disclosure. 
         FIG. 18  is a detail view of an example pull cable attachment assembly according to at least one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It is nevertheless understood that no limitation to the scope of the disclosure is intended. Any alterations and further modifications to the described devices, systems, and methods, and any further application of the principles of the present disclosure are fully contemplated and included within the present disclosure as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one embodiment may be combined with the features, components, and/or steps described with respect to other embodiments of the present disclosure. For the sake of brevity, however, the numerous iterations of these combinations will not be described separately. 
       FIG. 1  depicts a diagrammatic view of an ultrasonic imaging system  100  according to an embodiment of the present disclosure. In some embodiments, the ultrasonic imaging system includes a TEE probe. Referring to the embodiment of  FIG. 1 , the TEE probe  110  includes a gastroscope  130  in communication with a handle  120 , and the handle  120  is in communication with a console  180 , that may include a housing  182 , processor  184 , memory  186 , and display  188 . The processor  184 , memory  186  and display  188  may be integral to the console or may be removable or otherwise separate. The memory may include either or both of random access memory (RAM) and long-term storage including but not limited to a hard disk drive (HDD), solid state disk (SSD), CD-ROM, flash drive, or other related technologies. 
     An ultrasound transducer array  135  disposed at a distal portion of the gastroscope  130  may obtain ultrasonic imaging data and transmit the ultrasonic imaging data to the console  180 , via communication lines extending through the gastroscope  130 , the handle  120 , and a cable extending between the TEE probe  110  and the console  180 . Additionally, the gastroscope  130  and the ultrasound transducer array  135  may receive control data from the console  180  via the handle  120 , or may receive control inputs directly from control surfaces on the handle  120 , to control various aspects of a TEE scan, such as one or more firing sequences of an ultrasonic transducer array, and the movement or flexion of the distal portion of the gastroscope  130 . 
     In some embodiments, the gastroscope  130  transmits the ultrasonic imaging data to the console  180  through the handle  120 . The handle  120  may also include electronic components to modulate or process the ultrasonic imaging data being transmitted to the console  180 . 
       FIG. 2  is a side elevation view of a TEE probe, and depicts a TEE probe  210 , including a gastroscope  130 , a handle  120 , a console interface cable  270 , and a connector  175 . A TEE handle  120  is permanently connected to the gastroscope at a probe interface connection  155  through which continuous pull cables, power wires, signal wires, and other supporting hardware may be routed. The handle  120  is also permanently connected to the console interface cable  270  at a console interface cable connection  275 , through which continuous power wires, signal wires, and other supporting hardware may be routed. A distal end of the cable  270  is coupled to the handle  120  at the console interface cable connection  270 . A proximal end of the cable  270  is coupled to the connector  175 . The connector  175  can be removably, mechanically coupled to the housing  182  of the console  180  to facilitate signal communication between the console  180 , handle  120 , and/or the transducer array  135 . The connector  175  can be referenced as a patient interface module (PIM) in some embodiments. The TEE probe  210  comprises an integral unit wherein the gastroscope  130  and console interface cable  270  are permanently fixed to the handle  20  at the permanent connections  155 ,  275  by adhesives, screws, welds, or other attachments which are not readily separated by a physician or user. 
     The term “permanent” may be used to refer broadly to a mode of coupling or attachment that is not configured or designed for regular detachment and reattachment. Thus, although two coupled components can be physically separated, this disclosure may refer to the coupling or attachment as permanent when the components are not detached in the ordinary medical usage of the device. The terms coupled, coupling, coupled to, or connected, are used to refer broadly to any combination, attachment, or connection. This disclosure may refer to two components as coupled, even though they are permanently fixed to one another, or integrally formed as a single unit. Coupled, as used in this disclosure, contemplates direct and indirect modes of coupling or attachment, and modes of coupling or attachment that are removable. Two components may be referred to as coupled to one another even though they do not directly contact one another, or there are one or more conjoining components between the two components. Removable, separable, or detachable may be used to refer to a mode of coupling or attachment that is configured to be separated and reattached in the normal course of use of a device or system, such as before, during, or after a medical procedure. 
     The gastroscope  130  includes an elongate body  237 , a proximal portion  232 , and a distal portion  239  comprising a probe tip  240 . The probe tip  240  can include the ultrasound transducer array  135  ( FIG. 1 ). The elongate body  237  may be flexible such that it may be guided through the esophagus of the patient by operation of the movement controls  223 ,  225  coupled to the handle  120 . The movement controls  223  and  225  are control inputs to the gastroscope, and may take the form of wheels, knobs, dials, sliders, levers, or other related mechanical inputs. The device&#39;s response to actuation of the control inputs may enable a physician to control movement of the distal portion  239  of the gastroscope  130 . Controlling movement of the distal portion  239  of the gastroscope  130  can aid the physician to guide the gastroscope  130  through the physiology of the patient to the desired imaging location. A rigid or fixed configuration of a gastroscope could injure the patient, and may be unsuitable for ultrasonic imaging, which demands accurate placement and sufficient contact with the patient&#39;s physiology to obtain ultrasonic images. The exemplary handle  120  of  FIG. 2  also includes a beam-steering control  227  that may affect the geometry of an ultrasonic imaging beam. 
       FIG. 3  is a diagrammatic view of the handle portion of the TEE probe of  FIG. 2 . The gastroscope  130  includes first and second pull cables  333 ,  335  that are mechanically connected to first and second movement controls  223 ,  225  coupled to the handle  120 . Such a configuration may enable a physician to control movement of the distal portion  239  of the gastroscope  130 . Controlling movement of the distal portion  239  of the gastroscope  130  can aid the physician to guide the gastroscope  130  through the physiology of the patient to the desired imaging location, as ultrasonic imaging demands accurate placement and sufficient contact with the patient&#39;s physiology to obtain ultrasonic images. Thus, pull cables  333 ,  335  and flexible components aid the physician in obtaining ultrasonic images of the patient&#39;s organs. Because the first and second pull cables  333 ,  335  are mechanically connected to the first and second movement controls  223 ,  225 , a physician manipulating the first and second movement controls  223 ,  225  may receive tactile feedback from the distal portion  239  of the gastroscope  130  when the distal portion  239  presses against the walls of the esophagus. The exemplary handle of  FIG. 3  also includes transducer wiring  343  to convey signals from the gastroscope  130  to the console  180 . 
       FIG. 4  depicts a translucent isometric view of the interior mechanism  399  of an example TEE mid-handle assembly of a conventional TEE probe. The first movement control  222  and second movement control  224  create rotation in corresponding first pinion shaft  422  and second pinion shaft  424 , which then create linear motion in first rack  452  and second rack  454  via a rack-and-pinion mechanism. An additional first rack  452  and second rack  454  are on the far side of the visible mechanism and operate in conjunction with the visible racks  452  and  454  according to the same principle. The first racks  452  and second racks  454  are coupled to first and second pull cables to extend or contract them, and thus to control movement of the distal portion of the gastroscope. 
     The mechanism thus described is housed within a containment frame  459  that includes a gear housing  409  and a distal isolator  419 . The mid-handle mechanism also includes a brake switch  228  that may be engaged to apply resistance to the rotation of movement controls  222  and  224 . The rack and pinion mechanism requires tight manufacturing tolerances in order to function correctly, and may therefore be machined from steel, fully hardened beryllium copper, or other metals. The brake switch  228  may also be a multi-part assembly of four or more parts. The distal isolator may be machined from hard polymer materials such as 20% glass-filled polycarbonate. The rack frame or gear housing requires multiple apertures, through-holes, and threaded holes in order to accommodate other parts in the mid-handle assembly  399 , and these features may require rather strict manufacturing tolerances. The gear housing may therefore be machined from metals such as nickel-plated 6061-T6 aluminum. 
       FIG. 5A  is a side elevation view of a lateral side of a distal portion  239  of a TEE probe gastroscope  130 , illustrating various modes of anterior and posterior flexion of the distal portion  239 , which includes an imaging element  542 . The anterior/posterior flexion and right/left flexion may be accomplished by retracting and releasing one or more pull cables corresponding to one or more modes of movement. In some embodiments, the physician may control the anterior or posterior flexion of the distal portion  239  of the gastroscope  130  by retracting or releasing the first pull cable  333 . As the first pull cable  333  may comprise a plurality of individual cables or wires, controlling the anterior or posterior flexion of the distal portion of the gastroscope  130  may include retracting one of the individual wires of the first pull cable  333 , while leaving another of the individual wires of the first pull cable  333  static. 
       FIG. 5B  is an elevation view of a front side of the distal portion  239  of the TEE probe gastroscope  130  of  FIG. 5A , illustrating left and right flexion of the distal portion  239 , which includes imaging element  542 . The right/left flexion may be accomplished by retracting and releasing one or more pull cables corresponding to one or more modes of movement. In some embodiments, the physician may control the anterior or posterior flexion of the distal portion  239  of the gastroscope  130  by retracting or releasing the second pull cable  335 . As the second pull cable  335  may comprise a plurality of individual cables or wires, controlling the left and right flexion of the distal portion of the gastroscope  130  may include retracting one of the individual wires of the second pull cable  335 , while leaving another of the individual wires of the second pull cable  335  static. 
       FIG. 5C  is a side elevation view of the front side of the distal portion of the TEE probe of  FIG. 5A , illustrating modes of physical movement including counterclockwise rotation, clockwise rotation, advanced and withdrawn positioning of the distal portion. Such motions can be achieved by manually adjusting the gastroscope  130 , such as by rotating the handle to rotate the gastroscope  130  within the esophagus of the patient. A physician may also advance or withdraw the distal portion  239  of the gastroscope  130  within the esophagus of the patient by advancing or withdrawing the handle toward or away from the patient&#39;s esophagus. 
       FIG. 5D  is an isometric view of the distal portion of the TEE probe of  FIG. 5A , illustrating increasing and decreasing multi-plane angles of an ultrasonic transducer. The electronic modes of movement depicted in  FIG. 5D  may not require physical manipulation of the distal portion of the gastroscope, such as the modes of movement depicted in  FIGS. 5A-5C , but may be accomplished by controlling one or more electronic aspects of an ultrasonic transducer array or imaging element  542 , such as the timing of firing and receive sequences. This may be initiated via electronic commands from the console  180  or from a beam-steering control  227  in the handle  120 . 
     Referring generally to  FIGS. 5A-5D , the illustrated various modes of movement and flexion of the distal portion  239  of the gastroscope  130  may be controlled by one or more user input selectors of the handle (e.g.,  223 ,  225 ,  FIG. 2 ). For example, in one embodiment, the anterior and posterior flexion of the distal portion  239  of the gastroscope  130  are controlled by a first user input selector  223 , while the left and right flexion are controlled by a second user input selector  225 . The rotating, advancing, and withdrawal of the distal portion  239  can be achieved by manually rotating, advancing, and withdrawing the handle  120  of the TEE probe  110 . The electronic or beam angle movement may be manipulated or adjusted by a third user input selector  227 . As described above, the user input selectors  223 ,  225 , and  227  may each comprise at least one of an electronic button, dials, capacitive touch sensors, levers, switches, knobs, joysticks, etc. 
       FIG. 6  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates friction belts according to at least embodiment of the present disclosure. The rotation of shaft  423  creates a linear motion in friction belt  623 , which is attached to pull cables  333  by two pull cable attachment assemblies  620 . The pull cable attachment assemblies  620  may comprise clips, clamps, collars, collets, sleeves, thimbles, swivels, swages, hooks, eye fittings, clevis fittings, stud fittings, ball and dome fittings, turnbuckles, tensioners, and other related mechanical fittings suitable for attaching to a pull cable, plus any appropriate housings, fasteners, and adaptors. The rotation of shaft  425  similarly creates a linear motion in fiction belt  625  which is attached to pull cables  335  by another pair of pull cable attachment assemblies  620 . Thus, the rotation of the shafts controls movements of the distal end  239  of the gastroscope  130 . Also pictured is the gear housing  410 . In an example, the friction belts  623  and  625  are nonconductive. 
     In an example, a portion of the pinion shafts  423  and  425  is internal to the gear housing  410 , and the portion of the shafts  423  and  425  that is external to the gear housing  410  is internal to the control knobs  223  and  225 , such that the shafts  423  and  425  are minimally exposed to view or not exposed to view in a fully assembled device. 
       FIG. 7  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates friction belts according to at least embodiment of the present disclosure. The wrapping of belts  623  and  625  around corresponding shafts  423  and  435  is visible. This embodiment includes a different type of pull cable attachment assembly  620 , and also includes an idler  720  to assist in the linear actuation of belts  623  and  625 , such that the belts  623  and  625  wrap around the pinion shafts and past the idler to give a push-pull action. The belts  623  and  625  may be made of elastomeric compounds molded over Kevlar, nylon, or metal reinforcement members to reduce stretch and increase life. Pull cable attachment assemblies  620  may be molded directly onto the friction belts. Also pictured is a base  730 . 
     In the example shown in the figure, the belts  623  and  625  are wrapped 180 degrees around the shafts  423  and  425  (i.e., partially positioned around a perimeter or circumference of the shaft), such that the two ends of each belt move in opposite directions when the shaft is rotated. It should be understood that other degrees of wrapping are possible, including those that yield substantially opposite motion (e.g., 170 or 190 degrees), those that yield substantially similar motion (e.g., 10 degrees, 0 degrees, or 370 degrees), and otherwise. 
       FIG. 8  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates timing ladders or timing ladder belts according to at least embodiment of the present disclosure. In a manner analogous to  FIG. 6 , timing ladder  825  is coupled to pinion shaft  425  inside gear housing  410  such that rotation of shaft  425  creates linear motion in timing ladder  825 . However, unlike the friction belts  623  and  625  of  FIG. 6 , the timing ladder  825  includes features that may engage the teeth of a gear or pinion, such that friction is not required in order for the ladder to hold its position. The ladder belt  825  wraps around the corresponding pinion shaft  425  to create a push-pull action. Ladder belt  825  may be made from elastomeric compounds molded over steel, Kevlar, or nylon reinforcement members to reduce stretch and increase life. An additional ladder belt may be added to the mid-handle mechanism to wrap around and engage with pinion shaft  423 , such that one ladder belt may control left/right flexion of the distal portion  239  and probe tip  240 , and the other ladder belt may control anterior/posterior flexion of the distal portion  239  and probe tip  240 . 
     Pinion shaft  423  is also pictured. In an example, the timing ladder  825  is nonconductive. Pull cable attachment assembly  620  may be mechanically attached to and/or molded into the timing ladder  825 . 
       FIG. 9  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates pulley cables according to at least one embodiment of the present disclosure. In a manner analogous to  FIGS. 6 and 8 , pulley cable  925  is coupled to shaft  425  inside gear housing  410  such that rotation of shaft  425  creates linear motion in pulley cable  925 . Shaft  423  is also pictured. The pull cable  335  attach to pulley cable  925  via pull cable attachment assemblies  620 , aided by swaged balls  920  at the ends of pulley cable  925 . 
     In an example, the pulley cable  925  is made from a non-metallic, non-conductive rope such as Kevlar or similar material. In another example, the pulley cable  925  is made from a polymer-overcoated metal cable. A pull cable attachment device  620  such as a threaded collet can be held captive on either end of the Kevlar ropes and used to attach to and adjust final cable tension. An additional pulley cable may be added to the mid-handle mechanism to wrap around and engage with shaft  423  in the same manner, such that one of the pulley cables may control left-right deflection of the distal portion  239  and probe tip  240 , and the other pulley cable may control anterior/posterior deflection of the distal portion  239  and probe tip  240 . 
       FIG. 10  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates pulley cables according to at least embodiment of the present disclosure. In this view, the gear housing  410  is not shown, such that the association of pulley cable  925  with shaft  425  can be seen. An additional swaged ball  920  in the middle of cable  925  keeps it from sliding around shaft  425 . Multiple balls may be swaged onto the Kevlar rope at timed locations if control knob rotates more than 180 degrees. Shaft  423  is also pictured. 
       FIG. 11  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates pulley cables according to at least embodiment of the present disclosure. This view provides detail on a swaged ball or screw attachment  920  that is provided in the middle of pulley cable  923  and fits into a recess  1110  in shaft  423  to keep pulley cable  923  from slipping with regard to shaft  423 . Also pictured are pulley cable  925 , gear housing  410 , three pull cable attachment assemblies  620 , and the distal isolator  420 . 
       FIG. 12  is an isometric view of a portion of the mid-handle mechanism of an example TEE probe that incorporates pulley cables according to at least embodiment of the present disclosure. This view includes shaft  423 , which is inverted 180 degrees from its orientation in  FIG. 11 . Pulley cable  923  wraps around shaft  423  and anchors to it with a swaged ball or screw attachment  920 . Pulley cable  923  attaches to pull cables  333  via the pull cable attachment assemblies  620 . The use of an anchored pulley cable allows the shaft  423  to be a simple pulley shaft rather than a toothed gear shaft or pinion shaft, thus reducing the material requirements, manufacturing tolerances, and geometric complexity of the part. 
       FIG. 13  is an isometric, exploded view of a portion of the mid-handle mechanism of an example TEE probe that incorporates timing belts according to at least embodiment of the present disclosure. In a manner analogous to the timing ladders of  FIG. 8 , timing belts  1323  and  1325  engage with pinion shafts  423  and  425  such that a rotation of either shaft causes a linear motion in the corresponding timing belt, which then creates linear motion in the pull cable attachment assembly  620  to move the corresponding pull cable  333  or  335 . Also pictured is a brake switch  229  that, due to its 3D shape, applies resistance to the rotation of pinion shafts  423  and  425  when the brake switch  229  is rotated into its engaged position, and permits shafts  423  and  425  to rotate when brake switch  229  is rotated into its disengaged position. 
     In this embodiment, the containment frame  460  comprises a distal isolator  420 , gear housing  410 , and header  1310 . Also pictured is a floating, nonrotating interior shaft  1340  that sits between the inner pinion shaft  423  and outer pinion shaft  425  for 2 way articulation. The purpose of this shaft  1340  is to isolate any motion that could otherwise be transferred from either inner to outer or outer to inner control shafts during operation; this may eliminate or nearly eliminate cross-coupling of motion between the two control knobs. In an example, the floating shaft  1340  is mechanically constrained from rotating by connection to internal frame. The floating shaft  1340  may be formed as part of the gear housing  410  or base  730 . 
     In an example, parts of the shafts  423 ,  425 , and  1340  are located interior to the containment frame  460 , and the parts that are exterior to the containment frame  460  are interior to the control knobs  223  and  225 , such that in a fully assembled device they are minimally exposed or not exposed to view. In an example, the timing belts are nonconductive, and may be made of elastomeric compounds molded over Kevlar, nylon, or metal reinforcement members to reduce stretch and increase life. Pull cable attachment assemblies  620  may be molded directly onto the timing belts, although the form and materials of such interface assemblies are specific to each embodiment and may include additional features such as screw tension adjustments. 
       FIG. 14 a    is an isometric view of a portion of the mid-handle mechanism  399  of a conventional TEE probe that uses a rack and pinion mechanism to transfer motion from the control wheels to the pull cables. Visible are the control wheels  222  and  224 , brake switch  228 , gear housing  409 , distal isolator  419 , rack actuators  452  and  454 , and pull cable attachment assembly  619 . The rack and pinion mechanism requires tight manufacturing tolerances in order to function correctly, and may therefore be machined from steel, fully hardened beryllium copper, or other metals. The brake switch  228  may also be a multi-part assembly of four or more parts. The distal isolator may be machined from hard polymer materials such as glass-filled polycarbonate. The rack frame or gear housing provides a rather complex shape that may be machined from metals such as 6061-T6 aluminum. 
       FIG. 14 b    is an isometric view of a portion of the mid-handle mechanism  400  of an example TEE probe that incorporates timing belts according to at least one embodiment of the present disclosure. Visible are the brake switch  229 , pull cable  333 , gear housing  410 , pinion shafts  423  and  425 , pull cable attachment assembly  620 , header  1310 , and timing belts  1323  and  1325 . A reader of ordinary skill in the art will understand that the assembly of  FIG. 14 b    has similar overall size and shape to that of  FIG. 14 a   , and is operated in the same manner, but in accordance with the disclosure of  FIGS. 6-13  it has a greatly simplified internal structure vs. that of  FIGS. 4 and 14   a , and includes a smaller overall number of parts. For example, the gear housing  410  and distal isolator  420  of the containment frame  460  may be formed as a single piece, with fewer openings, through-holes, threaded holes, and other complex features. The brake switch assembly may also be monolithic (i.e., formed as a single piece). The timing belts  1323  and  1325  each replace multiple components of the rack-and-pinion system, and may require significantly looser manufacturing tolerances such that, for example, the brake switch  229 , pinion shafts  423  and  425 , and containment frame  460  may be made rapidly and inexpensively from cast-molded or injection-molded plastic, rather than machined from steel, aluminum, fully hardened beryllium copper, glass-filled polycarbonate, or other metals or polymers requiring substantially greater time and cost. Depending on the implementation, some of these components may continue to be made of metal in areas where wear, fatigue, or stretch are concerning. For example, in some embodiments, the brake switch and pinion shafts are machined from metal. 
       FIG. 15  is an isometric view of a portion of the mid-handle mechanism  400  of an example TEE probe that incorporates timing belts according to at least one embodiment of the present disclosure. This embodiment includes an assembly that may be manufactured and assembled more easily than the current TEE probe mid-handle assembly of  FIGS. 4 and 14   a . Visible in this view are the control wheels  223  and  225 , brake switch  229 , pull cables  333  and  335 , gear housing  410 , distal isolator  420 , pull cable attachment assemblies  620 , base  730 , header  1310 , timing belts  1323  and  1325 , and a number of fasteners  1510 . 
     In an example, parts of the shafts  423 ,  425 , and  1340  are located interior to the containment frame  460 , and the parts that are exterior to the containment frame  460  are interior to the control knobs  223  and  225 , such that in a fully assembled device they are minimally exposed or not exposed to view. 
       FIG. 16  is an isometric view of a tape drive according to at least one embodiment of the present disclosure. In a manner analogous to the timing belts and timing ladders already disclosed, a tape drive can convert the rotational motion of a shafted gear into linear motion of a tape. As with a timing belt or timing ladder, the tape incorporates features that may engage with teeth or other features of a gear such that the tape does not slip with respect to the gear and does not require friction in order to rotate along with the gear. Visible in this view are a gear  1610 , drive tape  1630 , and a socket  1620  through which a shaft may be placed. The incorporation of a tape drive within the gear housing, in place of pulley cables, timing ladders, timing belts, or friction belts will be understood by a person of ordinary skill in the art, and may for example offer one or more of increased material strength, decreased component stretch, comparable manufacturing efficiency, and improved reliability and lifespan vs. the friction belt, timing ladder, timing belt, and pulley cable designs described hereinabove. In an example, the drive tape  1630  is nonconductive. 
       FIG. 17  is an isometric view of a portion of the mid-handle mechanism  400  of an example TEE probe that incorporates timing belts according to at least one embodiment of the present disclosure. This figure is analogous to  FIG. 15 , except that it includes an outer handle casing  280  as shown for example in  FIG. 2 , in order to more fully convey the relationship of the mid-handle mechanism  400  to the whole of the handle  120 . Also visible are the control wheels  223  and  225 , brake switch  229 , gear housing  410 , distal isolator  420 , pull cable attachment assemblies  620 , and timing belts  1323  and  1325 . 
       FIG. 18  is a detail view of an example pull cable attachment assembly according to at least one embodiment of the present disclosure. Visible are two pull cable attachment assemblies  620 , along with pulley cables  923  and  925 , and fasteners  1510  to help connect the pulley cables  923  and  925  to the pull cable attachment assemblies  620 . 
     After becoming familiar with the teachings herein, persons of ordinary skill in the art will recognize that the disclosed TEE probe mid-handle assembly provides a substantially less complicated assembly that is naturally electrically isolated, and is easier and less costly to build in production, than existing TEE probe mid-handle assemblies. 
     Persons skilled in the art will also recognize that the apparatus, systems, and methods described above can be modified in various ways. Accordingly, persons of ordinary skill in the art will appreciate that the embodiments encompassed by the present disclosure are not limited to the particular exemplary embodiments described above. In that regard, although illustrative embodiments have been shown and described, a wide range of modification, change, and substitution is contemplated in the foregoing disclosure. It is understood that such variations may be made to the foregoing without departing from the scope of the present disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the present disclosure.