Patent Publication Number: US-2012035596-A1

Title: Disposable Drive Interface for Longitudinal Movement of an Elongate Medical Device

Description:
BACKGROUND OF THE INVENTION 
     a. Field of the Invention 
     This invention relates to a system for controlling longitudinal movement of elongate medical devices such as catheters. In particular, the instant invention relates to a disposable drive interface kit having relatively few parts that enables transfer of motive force from a drive system to the medical device while permitting reuse of the drive system. 
     b. Background Art 
     Catheters are used for to perform a variety of tasks within human bodies and other bodies including the delivery of medicine and fluids, the removal of bodily fluids and the transport of surgical tools and instruments. In the diagnosis and treatment of atrial fibrillation, for example, catheters may be used to deliver electrodes to the heart for electrophysiological mapping of the surface of the heart and to deliver ablative energy to the surface among other tasks. Catheters are typically routed to a region of interest through the body&#39;s vascular system. In a conventional approach, an introducer is used to puncture the skin surface and a sheath having an inner diameter greater than the outer diameter of the catheter is threaded through the vasculature to a region of interest. The catheter is then moved longitudinally through the sheath to the region of interest. The catheter may be advanced and retracted manually by the clinician. Alternatively, or in addition, the catheter may be advanced and retracted using electromechanical drive systems. 
     Several conventional drive systems are shown in U.S. Pat. No. 7,276,044. In one embodiment of a drive system (shown in FIG. 14 of U.S. Pat. No. 7,276,044), a catheter is received within a channel defined in the upper surface of a housing for the drive system and is placed between opposed wheels with one of the wheels driven by a motor. The disclosed embodiment has the drawback that all or substantially all of the drive system is generally disposed of after use. Because much of the drive system—including the housing—comes into contact with the catheter, the drive system must be disposed of after use or sterilized using conventional sterilization techniques such as ethylene oxide (EtO) gas or irradiation. Because the drive system generally includes sensitive electronic components, sterilization is difficult, expensive and often not cost effective. 
     The inventor herein has recognized a need for a disposable drive interface kit for longitudinal movement of an elongate medical device such as a catheter that will minimize and/or eliminate one or more of the above-identified deficiencies. 
     BRIEF SUMMARY OF THE INVENTION 
     It is desirable to provide a disposable drive interface kit for controlling longitudinal movement of an elongate medical device such as a catheter. In particular, it is desirable to provide a disposable drive interface kit having relatively few parts that enables transfer of motive force from a drive system to the medical device while permitting reuse of the drive system. 
     In accordance with one embodiment of the invention, a disposable drive interface kit for controlling longitudinal movement of an elongate medical device is configured for attachment to a drive housing from which a driving member projects. The kit includes a detachable housing configured for removable attachment to the drive housing. The detachable housing has an inner side and an outer side. The inner side is configured to face the drive housing upon attachment of the detachable housing to the drive housing. The outer side defines a channel having a bottom and first and second opposed sides extending from the bottom and configured to receive the elongate medical device. The kit further includes a driven member configured for movement by the driving member and extending into the channel on the first side of the channel. The driven member defines a first surface configured to engage the elongate medical device. The kit further includes an idler member extending into the channel on the second side of the channel. The idler member defines a second surface opposing the first surface and configured to engage the elongate medical device. In accordance with several embodiments of the invention, the kit may further include a coupling member configured for attachment to one of the detachable housing and the drive housing and configured to support a tubular body such as an introducer sheath through which the elongate medical device may be moved longitudinally. 
     In accordance with another embodiment of the invention, a method of controlling longitudinal movement of an elongate medical device is provided. The method includes the step of attaching a detachable housing to a drive housing from which a driving member projects. The detachable housing has an inner side and an outer side. The inner side is configured to face the drive housing upon attachment of the detachable housing to the drive housing and the outer side defines a channel having a bottom and first and second opposed sides extending from the bottom and configured to receive the elongate medical device. The method further includes the step of engaging a driven member with the driving member for rotation therewith. The driven member extends into the channel on the first side of the channel and opposes an idler member extending into the channel on the second side of the channel. The method further includes the steps of inserting the elongate medical device into the channel between opposed surfaces of the driven member and the idler member and actuating the drive member to move the elongate medical device in a longitudinal direction. Finally, the method includes the steps of removing the elongate medical device from the channel and detaching the detachable housing from the drive housing. 
     A drive interface kit in accordance with the present invention is advantageous because it has relatively few components and allows reuse of various drive system components. The drive interface kit provides a mechanism for physically separating those components that come into contact with the catheter or similar medical device from other drive system components. In this manner, the other drive system components and be reused with a resulting savings in terms of costs and resources. 
     The foregoing and other aspects, features, details, utilities and advantages of the present invention will be apparent from reading the following description and claims, and from reviewing the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a drive system including a drive interface kit in accordance with one embodiment of the present invention. 
         FIG. 2  is an exploded perspective view of the drive system of  FIG. 1 . 
         FIG. 3  is a plan view of a portion of the drive interface kit of  FIG. 1 . 
         FIG. 4  a perspective view of a drive system including a drive interface kit in accordance with another embodiment of the present invention. 
         FIG. 5  is a flow chart illustrating a method for controlling longitudinal movement of an elongate medical device in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views,  FIG. 1  illustrates a drive system  10  for controlling longitudinal motion of an elongate medical device  12 . Drive system  10  may include a drive housing  14  from which a driving member  16  projects (best shown in  FIG. 2 ), a controller  18  and a drive interface kit  20  in accordance with one embodiment of the invention. 
     Device  12  is provided for use in diagnostic or treatment procedures on a body. Device  12  may comprise a catheter for delivery of medicine or fluids to a region of interest in a body, removal of bodily fluids and/or transporting surgical tools or instruments within the body. Device  12  may comprise, for example, an electrophysiological (EP) catheter for use in gathering EP data associated with cardiac tissue. Device  12  may alternatively comprise an intracardiac electrocardiography (ICE) catheter for generating an internal image of the heart such as one of the catheters sold by St. Jude Medical, Atrial Fibrillation Division, Inc. under the registered trademark “VIEWFLEX.” Device  12  may alternatively comprise an ablation catheter for providing ablation energy (e.g., radiofrequency, ultrasound, cryogenic, laser or other light) to tissue within the body. Device  12  may include a cable connector or interface  22 , a handle  24 , and a shaft  26  having a proximal end  28  and a distal  30  end (as used herein, “proximal” refers to a direction toward the end of the catheter near the clinician, and “distal” refers to a direction away from the clinician and (generally) inside the body of a patient). Device  12  may also include other conventional components not illustrated herein and particular to the application of device  12  including, for example, electrodes, sensors and corresponding conductors or leads. 
     Connector  22  provides mechanical, fluid and electrical connection(s) for device  12 . Connector  22  may provide connections to, for example, an irrigation fluid pump or an ablation generator. Connector  22  is conventional in the art and may be disposed at a proximal end of device  12 . 
     Handle  24  provides a location for the clinician to hold device  12  and may further provides means for steering or guiding shaft  26  within the body. For example, handle  24  may include means to change the length of a guidewire extending through device  12  to distal end  30  of shaft  26  to steer shaft  26 . Handle  24  is also conventional in the art and it will be understood that the construction of handle  24  may vary. 
     Shaft  26  is an elongated, tubular, flexible member configured for movement within the body. Shaft  26  may support electrodes, sensors, associated conductors, and possibly additional electronics used for signal processing or conditioning. Shaft  26  may also permit transport, delivery and/or removal of fluids (including irrigation fluids and bodily fluids), medicines, and/or surgical tools or instruments. Shaft  26  may be made from conventional materials such as polyurethane and defines one or more lumens configured to house and/or transport electrical conductors, fluids or surgical tools. Shaft  26  may be introduced into a blood vessel or other structure within the body through a conventional introducer sheath  32  or another tubular body through which device  12  may be moved longitudinally. Shaft  26  may then be steered or guided through the body to a desired location with guide wires or other means known in the art. Introducer sheath  32  is conventional in the art and may include a handle  34  or hub at a proximal end of a sheath  32 . The handle  34  may contain a hemostasis valve and movement of sheath  32  may be controlled through handle  34 . Handle  34  also defines a lumen coaxially aligned with sheath and through which shaft  26  extends and additional lumens for passage of conductors and fluids to or from electrical and fluid connectors. 
     Drive housing  14  is provided to house mechanical and possibly electrical components used to generate a motive force in driving member  16 . Housing  14  provides structural support for the components and protects the components from foreign objects and elements. Housing  14  also provides a base for mounting components of drive interface kit  20  as described in greater detail hereinbelow. Drive housing  14  may be made from conventional plastics. Referring to  FIG. 2 , in the illustrated embodiment housing  14  includes a base  36  and a lid  38 . Base  36  defines a bottom wall  40  and a plurality of side walls  42 ,  44 ,  46 ,  48  extending generally perpendicular from bottom wall  40 . Base  36  further defines a connector  50  extending from side wall  42  for a purpose described hereinbelow. Lid  38  defines a top wall  52  and a plurality of side walls  54 ,  56 ,  58 ,  60  configured to engage side walls  42 ,  44 ,  46 ,  48  of base  36 . Top wall  52  includes an opening through which driving member  16  extends. Lid  38  may also define a pair of notches  62 ,  64  on opposite sides of lid  38 . Notches  62 ,  64  each define an inclined surface  66  angling from top wall  52  inward towards the center of lid  38  for a purpose describe hereinbelow. When coupled together, base  36  and lid  38  define an enclosed space in which one or more components used to impart motive force to driving member  18  are located. These components may include, for example, one or more shafts and gears. The components may also include a conventional motor. Alternatively, the motor could be located external to drive housing  14  with a motor shaft extending into housing  14 . Drive housing  14  may include an electrical connector through which control signals (including, for example, motor control signals) and feedback signals (including, for example, motor position sensor signals) may be exchanged with controller  18 . 
     Driving member  16  is provided to generate a motive force. In the illustrated embodiment, driving member  16  comprises a cogwheel configured for rotation about a rotational axis  68  and with a set of radially outwardly extending teeth  69 . It should be understood, however, that driving member  16  could assume a variety of forms. Driving member  16  may be driven by a motor within or external to drive housing  14 . Driving member  16  could alternatively be driven by a motive force provided by manually by a clinician. 
     Controller  18  provides a means for controlling the operation of various components of system  10  and device  12 . Controller  18  may also perform a variety of tasks depending on the nature of device  12  such as determining the geometry or EP characteristics of a region of interest, generating images of the region of interest for output to a display (not shown) or controlling the delivery of ablative energy to the region of interest. Controller  18  may comprise a programmable microprocessor or microcontroller or may comprise an application specific integrated circuit (ASIC). Controller  18  may include a central processing unit (CPU) and an input/output (I/O) interface through which controller  18  may receive a plurality of input signals including signals generated by device  12  and by motor position sensors (e.g. a rotary encoder) and generate a plurality of output signals including those used to control and/or provide data to the motor and device  12 . Controller  18  may implement a dead man&#39;s switch and/or velocity limit switches as failsafe mechanisms for controlling device  12 . 
     Referring again to  FIG. 1 , drive interface kit  20  is provided as a disposable interface between the other components of drive system  10  and device  12 . Kit  20  includes a detachable housing  70 , driven member  72 , and idler member  74 . Kit  20  may also include means, such as spring  76  (shown in  FIG. 3 ) for biasing idler member  74  in a direction towards driven member  72 , means, including actuator  78  and retainer  80 , for urging idler member  74  in a direction away from driven member  72  against the force of spring  76 , and coupling member  82 . 
     Housing  70  provides structural support for idler member  74  and provides a guide for device  12 . Housing  70  may be made from conventional plastics. In the illustrated embodiment, housing  70  includes a top wall  84  and a plurality of side walls  86 ,  88 ,  90 ,  92  generally perpendicular to top wall  84 . Together, top wall  84  and side walls  86 ,  88 ,  90 ,  92  define an inner side  94  (see  FIG. 3 ) and outer side  96  to housing  70 . 
     Top wall  84  defines a channel  98  extending longitudinally from side wall  86  to side wall  88  and disposed between side walls  90 ,  92  that is configured to receive and guide medical device  12  and, particularly, shaft  26  of device  12  in the illustrated embodiment. Channel  98  is open at the top and defines a bottom  100  and opposed sides  102 ,  104 . Sides  102 ,  104  of channel  98  include apertures  106 ,  108  through which driven and idler members  72 ,  74  may extend through to engage shaft  26  of device  12 . Top wall  84  also includes a slot  110  extending perpendicular to channel  98  on the side of channel  98  on which idler member  74  is disposed and extending between the inner and outer sides  94 ,  96  of housing  70 . Slot  110  is configured to receive an inwardly extending post (not shown) or similar structure connecting actuator  78  to retainer  80  for a purpose described hereinbelow. 
     Side walls  86 ,  88 ,  90 ,  92  are configured to engage top wall  52  of lid  38  of drive housing  14 . Opposing side walls  86 ,  88  each include a pair of outwardly extending posts  112  configured to receive pins (not shown) extending therebetween on which clips  114 ,  116  are mounted for rotation about a longitudinal axis of the pins. Clips  114 ,  116  are generally S-shaped in cross-section and are configured such that a lip  118  on one end of each clip  114 ,  116  engages a corresponding inclined surface  66  of a corresponding notch  62 ,  64  upon rotation of clips  114 ,  116  in one rotational direction in order to attach housing  70  to drive housing  14 . Rotation of clips  114 ,  116  in the opposite rotational direction disengages lip  118  from surface  66  to permit detachment of housing  70  from drive housing  14  for later disposal of housing  70 . Rotation of clips  114 ,  116  may be affected by applying torque to a lip  120  at an opposite end of either clip  114 ,  116  relative to lip  118 . Although  FIGS. 1-3  illustrate a particular means for attaching housing  70  to housing  14  including rotatable clips  114 ,  116  mounted on housing  70  and configured to engage inclined surfaces  66  in housing  14 , it should be understood that a variety of means for attaching housing  70  to housing  14  could be employed without departing from the spirit of the present invention including, for example, aligned posts and bores, temporary fasteners such as screws and other structures. Upon attachment of housing  70  to drive housing  14 , one end of each side wall  86 ,  88 ,  90 ,  92  opposite top wall  84  engages top wall  52  of lid  38  of housing  14  such that inner side  94  of housing  70  is configured to define an enclosed space containing driving member  16  and partially containing driven and idler members  72 ,  74 . 
     Driven member  72  provides a means for imparting a motive force to device  12 , and particularly shaft  26  of device  12 , to move device  12  longitudinally, thereby advancing or retracting shaft  26  within introducer sheath  32  and the body. Driven member  72  may be made from conventional plastics. Driven member  72  is configured for movement by driving member  16 . In the illustrated embodiment, driven member  72  comprises a wheel and is configured for rotation by driving member  16 . A radially inner surface of the wheel defines a hub from which a plurality of radially inwardly extending teeth  122  extend that are configured to mesh with teeth  69  of driving member  16 . A radially outer surface of the wheel defines a groove  124  with a surface configured to engage medical device  12  and, in particular, shaft  26  of device  12 . The side walls of groove  124  formed by opposed lips at either axial end of the wheel may be curved such that groove  124  is substantially concave or may be straight such that groove is substantially rectilinear in cross-section. Upon attachment of housing  70  to drive housing  14 , driven member  72  is configured to be partially disposed within the enclosed space between inner side  94  of housing  70  and top wall  52  of lid  38  of housing  14 . Driven member  72  is further configured to extend into channel  98  through aperture  106  in side  102  of channel  98  to engage device  12 . 
     Idler member  74  provides a means for maintaining engagement of device  12  with driven member  72 . Idler member  74  may be made from conventional plastics. Referring to  FIG. 3 , idler member  74  comprises a wheel in the illustrated embodiment and is supported within housing  70  on a post  126  that extends downwardly from a movable plate  128 . A radially outer surface of idler member  74  defines a groove  130  with a surface—opposing the surface defined by groove  124  of driven member  72 —configured to engage medical device  12  and, in particular shaft  26  of device  12 . The side walls of groove  130  formed by opposed lips at either axial end of the wheel may be curved such that groove  130  is substantially concave or may be straight such that groove is substantially rectilinear in cross-section. Upon attachment of housing  70  to drive housing  14 , idler member  74  is configured to be partially disposed within the enclosed space between inner side  94  of housing  70  and top wall  52  of lid  38  of housing  14 . Idler member  74  is further configured to extend into channel  98  through aperture  108  in side  104  of channel  98  to engage device  12 . Although driven member  72  and idler member  74  comprise wheels in the illustrated embodiment, it should be understood that driven member  72  and idler member  74  could take on other forms sufficient to provide opposed surfaces engaging device  12  including, for example, conveyor belts. 
     Spring  76  is provided to bias idler member  74  in a first direction towards driven member  72  such that opposed surfaces in driven and idler members  72 ,  74  securely engage device  12 . Spring  76  may comprise a compression spring or a formed flat spring. Referring to  FIG. 3 , spring  76  may be disposed about a rod  132  connecting retaining member  80  and plate  126  with spring  76  bearing on opposed surfaces on inner side  94  of housing  70  and plate  126 . 
     Actuator  78  and retainer  80  are provided to selectively urge idler member  74  in a direction away from driven member  72  against the force of spring  76  and may be made from conventional plastics. Retainer  80  is configured to receive one end of rod  132 . Actuator  78  is coupled to retainer  80  by a post extending through slot  110  in top wall  84  of housing  70 . Using actuator  78 , a clinician can move retainer  80  in a direction away from idler member  74  to overcome the force of spring  76  and move rod  132 , plate  128  and idler member  74  in the same direction to permit insertion or removal of medical device  12  from channel  98 . It should be understood that, although actuator  78  and retainer  80  have a particular form illustrated in the drawings, a variety of structures could be used to provide an opposing force to spring  76 . 
     Coupling member  82  provides a means for supporting introducer sheath  32  in a proper position and orientation relative to channel  98  in housing  70 . Coupling member  82  may be made from conventional plastics and is configured for attachment to one of housings  14 ,  70 . In the illustrated embodiment member  82  includes a connector  134  at one end configured to engage connector  50  extending from base  36  of drive housing  14  with the connector  134  in member  82  defining a rectilinear recess configured to receive connector  50  on drive housing  14 . It should be understood that the size, shape and form of connectors  50 ,  134  could be varied without departing from the spirit of the invention. At an opposite end of member  82  from connector  134 , side walls  136 ,  138 , and a rib  140  extending between side walls  136 ,  138  define a cradle or recess  142  configured to receive one end of sheath  32  such as handle  34  of sheath  32 . Recess  142  may be curved or otherwise configured for a particular sheath  32  and a center of recess  142  is aligned with channel  98  to prevent misalignment of device  12 . 
     Referring to  FIG. 4 , in an alternative embodiment of the invention, a coupling member  144  includes a pair of connectors  146 ,  148  and an intermediate tubular member  150  disposed between connectors  146 ,  148  that is configured to receive device  12 . Connectors  146 ,  148  and member  150  may be made from conventional plastics. Connector  146  is configured for attachment to one of housings  14 ,  70 . In the illustrated embodiment, connector  146  is attached to drive housing  14  and supported on a flange  152  extending from side wall  42  of base  36  housing  14  through, for example, a pin and hole arrangement. Connector  146  defines a tubular passage at an one end configured to support one end of tubular member  150  and provide a junction at which device  12  enters tubular member  150 . Connector  148  is disposed at an opposite end of tubular member  150  and defines a hub configured to receive one end of sheath  32  such as a handle  34  of sheath  32 . 
     Referring to  FIG. 5 , a method for controlling longitudinal movement of an elongate medical device such as device  12  is described. The method may begin with the step  154  of engaging driven member  72  with driving member  16  for rotation therewith. The method may continue with the step  156  of attaching detachable housing  70  to drive housing  14 . Step  156  may include the substeps  158 ,  160  of aligning notches  62 ,  64  and clips  114 ,  116  and then rotating clips  114 ,  116  to lock housing  70  in position relative to housing  14 . Idler member  74  may be mounted on post  126  prior to attachment of housing  70  to housing  14  such that idler member is biased towards driven member  72  by spring  76  upon attachment of housing  70  to housing  14 . The method may continue with the steps  162 ,  164  of attaching coupling member  82  or  144  to one of housing  70  and housing  14  (if coupling member  82  or  144  is not already attached to housing member  70 ) and placing a tubular body such as sheath  32  through which device  12  may be moved longitudinally on coupling member  82  or  144 . In particular, handle  34  may be inserted into recess  142  of coupling member  82  or into hub  148  of coupling member  144 . The method may continue with the step  166  of inserting shaft  26  of device  12  into said channel  98  of housing  70  between opposed surfaces of driven member  72  and idler member  74  and the step  168  of inserting shaft  26  of device  12  into sheath  32  (and particularly handle  34  of sheath  32 ). The method may then continue with the step  170  of actuating drive member  16  to move device  12  in a longitudinal direction. As discussed hereinabove, movement may be caused by motor or another motive power source (including, for example, by hand). Shaft  26  may be advanced and retracted in at various times during the procedure. Upon completion of the procedure, the method may continue with the step  172  of urging idler member  74  in a direction away from driven member  72 . As discussed hereinabove, actuator  78  may be moved to compress spring  76  and move idler member  74  in a direction away from driven member  72 . The method may then continue with the step  174  of removing device  12  from channel  98  and from sheath  32  (as well as removing sheath  32  from coupling member  82  or  144 ). The method may then conclude with the steps  176  and  178  of detaching housing  70  from drive housing  14  (e.g., by rotating clips  114 ,  116  to disengage the clips  114 ,  116  from notches  62 ,  64 ) and disengaging driven member  72  from driving member  16 . If coupling member  82  or  114  is attached to drive housing  14  as opposed to housing  70 , an additional step  180  of detaching member  82  or  114  from housing  14  may also be required. Housing  70 , driven member  72  (as well as idler member  74  and its mounting components) can then be disposed of while drive housing  14  may be reused. It should be understood that the above-described steps could occur in various orders and that the particular order illustrated in  FIG. 5  is exemplary only. For example, the order of steps  156 ,  162  could be reversed as could the steps  176 ,  180 . Steps  166  and  168  could also be reversed in order. 
     A disposable drive interface kit in accordance with the present invention is advantageous because it contains relatively few components and allows reuse of drive system components. The detachable housing locates the channel for device  12  in a separate, detachable, and disposable housing. As a result, the drive housing  14  does not come into contact with device  12  and does not require sterilization or disposal. Rather, the few components comprising kit  20  can be easily removed and disposed of to permit reuse of the drive system components. 
     Although several embodiments of this invention have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this invention. All directional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise and counterclockwise) are only used for identification purposes to aid the reader&#39;s understanding of the present invention, and do not create limitations, particularly as to the position, orientation, or use of the invention. Joinder references (e.g., attached, coupled, connected, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, joinder references do not necessarily infer that two elements are directly connected and in fixed relation to each other. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not as limiting. Changes in detail or structure may be made without departing from the invention as defined in the appended claims.