Abstract:
The present invention provides self-aligning rotational connectors. In an non-limiting embodiment, a catheter system comprises a catheter connectable to a drive unit. The catheter includes a rotator, and at least one orientating feature extending proximally from the rotator, and configured to be inserted into an orienting slot of a shaft connector of the drive unit. When the orienting feature is inserted into the slot of the shaft connector, the slot transmits torque from the shaft connector to the orientating feature, and therefore the rotator of the catheter. Electrical contacts are provided on the rotator and the shaft connector, wherein the contacts of the rotator are properly aligned with and engage the contacts of the shaft connector. Further, the shaft connector has a slopping surface that slops downward into the slot for automatically aligning the rotator rotationally with the shaft connector during insertion of the catheter into the drive unit.

Description:
FIELD OF THE INVENTION 
     The present invention relates to catheters, and more particularly to self-aligning rotational core connectors for catheters. 
     BACKGROUND INFORMATION 
     Intravascular ultrasound imaging systems (IVUS) are used to obtain ultrasound images inside a patient&#39;s body. An IVUS system typically includes an ultrasound catheter having a flexible catheter body adapted for insertion into the vascular system of the patient. To obtain ultrasound images, the catheter comprises an imaging core received within a lumen of the catheter body. The imaging core comprises an ultrasound transducer connected to the distal end of a flexible drive cable that extends to the proximal end of the catheter through the catheter lumen. The drive cable is used to rotate and longitudinally translate the transducer within the catheter lumen. The catheter includes electrical and mechanical connectors for electrically and mechanically connecting the catheter to a motor drive unit (MDU). The MDU includes a motor for rotating the imaging core, and transmits electrical signals to and from the transducer. 
     Currently two types of connections are used to connect the catheter to the MDU. The first type uses a stationary connector in which the rotating wiring of the transducer is converted to stationary wiring by means of a rotary transformer, slip ring or capacitive device housed in a catheter hub. Disadvantages of this approach include increased cost, increased hub size, and increased complexity. Because a rotary transformer or slip ring is installed in each catheter, there is the additional cost of purchasing or manufacturing the transformer or slip ring for each catheter as well as the additional labor cost for assembly. Also, the rotary transformer must be accommodated in the catheter hub, and as other signals are added, the size of the transformer, and hence the hub, may have to be enlarged. A catheter with a rotary transformer is more complex and requires that the fit of the components be within close-tolerances to perform this type of catheter cannot be tested until final assembly, at which time, if there is a problem with the catheter, the entire unit must be strapped. 
     The second type of connection uses a coaxial-type connector in which the mating contacts comprise a center pin and concentric spring loaded rings so that the catheter and MDU are properly mate regardless of the relative position of their connectors. The rotary transformer or slip ring that converts the rotating wiring to stationary wiring is house in the MDU. Disadvantages of this approach include limitations in the number of contacts available, greater complexity, and the potential for slippage in the mechanical coupling. The cost of the multiple contact coaxial connector can approach that of the rotary transformer. For more than two contacts, the coaxial connector becomes larger, complex, and expensive. Typically the contacts of the coaxial connector act as a mechanical coupling to transmit torque from the motor drive to the rotating portion of the catheter, and as the contacts in the motor drive wear, slippage can occur. 
     Therefore, there is a need for improved rotational connectors that overcome disadvantages of the prior art. 
     SUMMARY OF THE INVENTION 
     The present invention provides self-aligning rotational connectors for catheters and other applications were rotational alignment of mating connectors is desired without the need for manual alignment. 
     In an embodiment, a catheter system comprises a catheter connectable to a drive unit. The catheter includes an imaging core, a rotator coupled to a proximal end of the imaging core, and at least one orientating feature extending proximally from the rotator. The drive unit includes a shaft connector having at least one orienting slot, wherein the orienting feature of the catheter is configured to be inserted into the slot. When the orienting feature is inserted into the slot of the shaft connector, the rotator and imaging core rotate with the shaft connector, and the slot transmits torque from the shaft connector to the orientating feature, and therefore rotator and imaging core. Electrical contacts are provided on the rotator and the shaft connector. When the orienting feature is inserted into the slot of the shaft connector, the electrical contacts of the rotator are properly aligned with and engage the electrical contacts of the shaft connector. Further, the shaft connector has a slopping surface that slopes downward into the slot. During insertion of the catheter into the drive unit, the orienting feature engages the slopping surface of the shaft connector causing the shaft connector to automatically rotate. As the shaft connector rotates, the orientation feature slides down the slopping surface and into the slot, at which point the rotator is properly aligned rotationally with the shaft connector. 
     Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In order to better appreciate how the above-recited and other advantages and objects of the present inventions are objected, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. It should be noted that the components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. However, like parts do not always have like reference numerals. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely. 
         FIG. 1  is a perspective view of a catheter system in accordance with an embodiment of the invention. 
         FIG. 2A  is a back view of the proximal end of a catheter in accordance with an embodiment of the invention. 
         FIG. 2B  is a cross-sectional side view of the proximal end of a catheter in accordance with an embodiment of the invention. 
         FIG. 3A  is a perspective view of a two-slotted shaft connector in accordance with an embodiment of the invention. 
         FIG. 3B  is a top view of a two-slotted shaft connector in accordance with an embodiment of the invention. 
         FIG. 3C  is a side view of a two-slotted shaft connector in accordance with an embodiment of the invention. 
         FIG. 3D  is a front view of a two-slotted shaft connector in accordance with an embodiment of the invention. 
         FIG. 4  is a cross-sectional view of the proximal end of a catheter and a motor drive unit in accordance with an embodiment of the invention. 
         FIG. 5  is a cross-section view of the catheter connected to the motor drive unit in accordance with an embodiment of the invention. 
         FIG. 6A  is a perspective view of a one-slotted shaft connector in accordance with an embodiment of the invention. 
         FIG. 6B  is a top view of a one-slotted shaft connector in accordance with an embodiment of the invention. 
         FIG. 6C  is a side view of a one-slotted shaft connector in accordance with an embodiment of the invention. 
         FIG. 6D  is a front view of a one-slotted shaft connector in accordance with an embodiment of the invention. 
         FIG. 7A  is a perspective view of a four-slotted shaft connector in accordance with an embodiment of the invention. 
         FIG. 7B  is a top view of a four-slotted shaft connector in accordance with an embodiment of the invention. 
         FIG. 7C  is a side view of a four-slotted shaft connector in accordance with an embodiment of the invention. 
         FIG. 7D  is a front view of a four-slotted shaft connector in accordance with an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an exemplary catheter ultrasound imaging system  10  according to an embodiment of the invention. The imaging system  10  includes a catheter  15  adapted for insertion into the vascular system of a patient. The catheter  15  includes a flexible elongated catheter body  20  and an imaging core (not shown) within a lumen in the catheter body  20 . The imaging core comprises an ultrasound transducer, e.g., piezoelectric crystal (PZT), connected to the distal end of a drive cable, which extends through the catheter body  20 . The drive cable is used to rotate and longitudinally translate the transducer within the catheter  15 . The proximal end of the catheter  15  is detachably connected to a motor drive unit (MDU)  25 , which houses a motor for rotating the imaging core. 
     Referring to  FIG. 2B , the catheter  15  includes a catheter hub  30  at its proximal end for mechanically and electrically connecting the catheter  15  to the MDU  25 . The catheter hub  30  includes a non-rotating housing  35  and a rotator or rotating element  40  housed within the non-rotating housing  35 . The rotator  40  rotates within the non-rotating housing  35 . The catheter  15  includes orienting features  45  in the from of splines extending from the rotator  40 . The catheter  15  also include electrical contacts  50  on the rotator  40  for electrically coupling the catheter  15  to the MDU  25 . In this embodiment, the contacts  50  are in the form of connector pins extending from the rotator  40 . The catheter  15  further includes a stamped shaft  60  connecting the rotator  40  to the proximal end of the drive cable  55 , and a seal around the shaft  60 . The connector pins  50  are electrically coupled to the transducer of the imaging core via wires or coaxial cable (not shown) running through the shaft  60  and drive cable  55 . The connector pins  50  provide the electrical interface between the catheter  15  and the MDU  25  by inserting the pin connectors  50  into a female connector, e.g., sockets, in the MDU  25 , as explained further below. As shown in  FIG. 2A , the orientating splines  45  extend from opposite sides of the rotator  40 . Each spline  45  each has a sharp leading edge centered along the width of the spline  45 . 
       FIGS. 3A-3D  show a shaft connector  65  of the MDU  25  according to an embodiment of the invention. The proximal end of the shaft connector  65  is connected to the motor (not shown) of the MDU  25 , which rotates the shaft connecter  65 . The shaft  65  includes two outer orienting slots  67  at opposite sides. The orienting splines  45  of the catheter  15  are configured to fit into the orienting slots  67  of the shaft connector  65 . The shaft connector  65  further includes outer beveled surfaces  70  that slope downward into the orienting slots  67 . As shown in  FIG. 3C , each orientating slot  67  has two beveled surfaces  70  that slope into the slot  67  from opposite sides of the slot  67 .  FIG. 3B  shows a top view of the shaft connector  65 , in which the beveled surfaces  70  of the slots meet at sharp leading edges  75  centered between the slots  67 . The female connector, e.g., sockets, of the MDU  25  is housed within the shaft connector  65  and is accessible though an opening  80  in the shaft connector  65 . The female connector is configured so that it is properly aligned with the connector pins  50  of the catheter  15  when the splines  45  of the catheter  15  are inserted into the slots  67  of the shaft connector  65 . 
     Referring to  FIG. 4 , insertion of the catheter hub  30  into the MDU  25  will now be described. As shown in  FIG. 4 , the shaft connector  65  is positioned within a port  85  of the MDU configured to receive the catheter hub  30  therein. The catheter hub  30  is inserted into the port  85  of the MDU  25  such that the non-rotating housing  35  of the hub  30  sits firmly in the port  85 . The non-rotating housing  35  is locked in place in the port  85  of the MDU  25 . As the catheter hub  30  is inserted into the port  85 , the leading edges of the splines  45  reach the beveled surfaces  70  of the shaft connector  65 . As the hub  30  continues to be inserted into the port  85 , the engagement between the splines  45  and the beveled surfaces  70  of the shaft connector  65  converts the longitudinal insertion force exerted by the splines  45  into rotational force that causes the shaft connector  65  to rotate. The longitudinal insertion force is applied in a direction substantially parallel to the rotation axis of the shaft connector  65 . As the shaft connector  65  is rotated, the leading edges of the splines  45  slide down the beveled surfaces  70  of the shaft connector  65  and into the slots  67  of the shaft connector  65 , at which point the connector pins  50  are properly aligned with the connector in the shaft  65 . As the hub  30  continues to be inserted into the port  85 , the splines  45  slide longitudinally into the respective slots  67 , and the connector pins  50  of the hub  30  are inserted into the connector in the shaft  65  through the shaft opening  80 . Preferably, the splines  45 , slots  67  and beveled surfaces  70  are configured so that the connector pins  50  of the hub do not begin to engage the connector of the MDU until the full width of each spline  45  is in the respective slot  67 . This ensures that the connector pins  50  of the hub are properly aligned with the connector of the MDU before they engage each other. 
       FIG. 5  shows the catheter hub  30  fully inserted into the MDU  25 . As shown in  FIG. 5 , the MDU includes a female connector  95 , a drive shaft for connecting the shaft connector  65  to the motor (not shown) of the MDU  25 , and a rotary transformer  97  for electrically coupling the rotating wiring of the shaft to stationary wiring in the MDU  25 . Other means may be used to couple the rotating wiring of the shaft to stationary wiring in the MDU  25  including slip rings and capacitors. The connector pins  50  of the hub inserted into the female connector of the MDU  25  provide electrical coupling between the imaging core of the catheter  15  and the MDU  25  electronics. Other types of connectors may be used to electrically couple the catheter hub  30  to the MDU  25 . For example, the connector pins may be placed in the MDU, and the female connector in the catheter hub. Further, non-pin connectors may be used. The splines  45  inserted into the slots  67  provide mechanical coupling between the shaft connector  65  of the MDU and the drive cable  55  of the imaging core. As the shaft connector  65  is rotated by the motor of the MDU, the slots  67  of the shaft connector  65  transmit torque to the splines  45 , which in turn transmit the torque to the drive cable  55  of the imaging core. Thus, the splines  45  in the slots  67  provide the rotational driving force to the imaging core, thereby reducing mechanical stress on the connector pins  50 . 
     Referring to  FIG. 2A , the rotator  40  in the hub  30  comprises duplicate pairs of connector pins  50 , wherein the connector pins  50  in each duplicate pair are shorted together. For example, connector pins  50   b  and  50   d  both connect to the negative polarity of the transducer, and connector pins  50   a  and  50   c  both connect to the positive polarity of the transducer. This is done because there are two possible rotational alignments of the rotator  40  to the shaft connector  65  when the catheter  15  is connected to the MDU  25  depending on which spline  45  goes into which slot  67 . These two possible rotational alignments are oriented 180 degrees apart. The duplicate connector pins  50  are positioned on the rotator such that the pattern of connector pins  50  is the same for both possible rotational alignments. This is done by orienting the connector pins  50  of a duplicate pair 180 degrees apart with respect to the rotational axis of the rotator  40 . In  FIG. 2A , for example, the pattern of positive polarity connector pins  50   a  and  50   c  and negative polarity connector pins  50   b  and  50   c  is the same when the rotator  40  is rotated 180 degrees. The shaft connector  65  of the MDU has corresponding duplicate sockets (not shown). Thus, proper electrical coupling is made for both possible rotational alignments. 
     The catheter hub and shaft can have any number of splines and slots, respectively. For example,  FIGS. 6A-6D  show an embodiment in which the shaft  165  has a single slot  167 . In this embodiment, the catheter hub includes a corresponding single spline (not shown), and may be similar to the hub shown in  FIGS. 2A and 2B  with a single spline. In this embodiment, the shaft  165  includes an outer helical surface  170  that spirals downward into the slot  167 . In this embodiment, duplicate connectors pins are not needed because the there is only one possible rotational alignment. 
       FIGS. 7A-7D  show another embodiment in which the shaft  265  as four slots  267  spaced 90 degrees apart. In this embodiment, the hub includes four corresponding splines, and may be similar to the hub shown in  FIGS. 2A and 2B  with four splines spaced 90 degrees apart. Each orientating slot  267  has two beveled surfaces  270  that slope into the slot  267  from opposite sides of the slot  267 . The beveled surfaces  270  of the slots  267  meet at sharp leading edges  275  centered between the adjacent slots  267 . In this embodiment, the hub preferably has duplicate connector pins every 90 degrees since there are four possible rotational alignments between the rotator and the shaft in this embodiment. 
     The self-aligning connectors according to various embodiments of the invention provide several advantages. One advantage is that the rotational driving force to the imaging core is provide by the spline(s) in the slots(s), and not the electrical contacts of the catheter and shaft connector, thereby reducing mechanical stress on the contacts. Further, the rotary transformer or other coupling apparatus is housed in the MDU and not the catheter. Thus, a separate rotary transformer or other coupling apparatus does not need to be provided for each catheter, thereby reducing the per-unit cost of the catheters. In cases where the catheters are disposable, this reduces the cost of the disposable product. Further, the catheter can be assembled in two main sub-assemblies: the imaging core and the catheter body/hub. Each of these sub-assemblies can be tested separately prior to final assembly so that a defective sub-assembly can be discarded without scraping the entire assembly. After final assembly and testing, if one of the main sub-assemblies is defective, then the catheter can be disassembled, the defective part discarded, and the catheter reassembled with a replacement part replacing the defective sub-assembly. 
     The self-aligning connectors can be used in applications where precise rotational alignment of mating connectors is desired without the need for manual alignment. The self-alignment connectors are useful in cases where one or more parts rotate independently, alignment features end in random orientation, and there is a requirement that parts engage easily without the need for manual alignment. 
     In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. For example, the reader is to understand that the specific ordering and combination of process actions described herein is merely illustrative, and the invention can be performed using different or additional process actions, or a different combination or ordering of process actions. As a further example, each feature of one embodiment can be mixed and matched with other features shown in other embodiments. Additionally and obviously, features may be added or subtracted as desired. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.