Patent Publication Number: US-2011077591-A1

Title: Telescopic Guide Device for Catheters to Facilitate Their Insertion Into the Human Cardiovascular System

Description:
There is a known way of inserting flexible catheters into the cardiovascular system of the human body for diagnostic and/or therapeutic purposes, the catheters being, for example, of the type illustrated in  FIG. 1  of the appended drawings, each catheter being provided with a robust handle M whose front end M 1  is fixed to the catheter E and whose rear end carries a connector C for connection to the diagnostic instruments. If required, an annular slider A can be made to slide in both directions on this handle, thus causing the deflection of the distal end E 1  of the catheter by means of known connections inside the catheter, as indicated in broken lines in  FIG. 1 , to produce the deflection manoeuvres required during the insertion of the catheter into the human cardiovascular system and its removal therefrom. In normal use, appropriate movements are imparted to the handle M to make the catheter advance or withdraw by axial movements or rotate about its axis in both directions, and furthermore, as mentioned above, if said slider A is present it can be operated to subject the catheter, if required, to an operation of deflection or steering of its distal end which is usually provided with one or more electrodes Z. To facilitate the maneuvering of a catheter according to the example of  FIG. 1 , there is a known way of using an insertion and adaptation device as described in Italian patent 1363313 and in European publication No. 2 218 474 and corresponding US Application No. US-2010-0204680-A1, to which ample reference will be made. This device comprises a telescopic guide which is to be mounted on the catheter in advance, one end of this guide being designed for coupling to the end M 1  of the catheter handle as shown in the example of  FIG. 1 , while its other end is coupled to the introduction device whose cannula has previously been inserted into the patient&#39;s artery or vein, with the interposition of an adapter means which is fitted in a sealed way into the resilient seal of the introduction device and which carries its own sealing means for calibrated interaction with the diameter of the catheter, in such a way that the catheter can be made to slide and can rotate with a low degree of friction through the adaptation and introduction unit, while the portion of catheter lying between said unit and the handle M is kept rigid by said telescopic guide and is therefore in the optimal condition for reacting to the commands imparted to it through the handle M. 
     The known device to which reference is made presents difficulties in the coupling of the telescopic guide to the handle M, since, for any given outside diameter of the catheter E, the shape and dimensions of the front end M 1  of the handle M may vary from one manufacturer to another. Another limitation of the known device is that the coupling between the telescopic guide and the handle M of the catheter is such that the two parts form a single rigid body, and this condition gives rise to difficulties in the positioning and manoeuvring of the catheter. 
     In a preferred embodiment of the known device, the telescopic guide is formed by only two sections, and therefore the guide is excessively long when in its closed position, which complicates the packaging of the device in a sterile package and also complicates the use of the device. 
     Another limitation of the known device arises from the lack of reliability and security of the male and female screw means which is proposed for axially locking the catheter with respect to said adapter, since the activation and inactivation of this screw means takes a considerable time, and the screw means also acts directly in contact with the catheter, with the risk of damaging it. 
    
    
     
       The object of the invention is to overcome all of these and other problems and limitations of the prior art with an improved device as claimed in Claim  1  and in the subsequent dependent claims, the features and advantages of this device being made evident by the following description which refers to the figures of the three appended sheets of drawings, in which, in addition to  FIG. 1  which has already been described, 
         FIG. 2  is a perspective view of the device in use, with the catheter being inserted into the cardiovascular system of a patient; 
         FIGS. 3 and 4  show the device from above and from the side, with parts shown in section and with the telescopic guide shown in the closed position in which it is taken from the sterile packaging; 
         FIGS. 5 and 6  show in side view, with parts in section, the part of the device with the adapter and the axial catheter locking means, in the rest position and in the working position respectively; 
         FIG. 7  is a perspective view of the rotating stopping member of the locking means of  FIGS. 5 and 6 . 
     
    
    
       FIGS. 2 ,  3  and  4  show that the novel device comprises a first unit  1  for fixing the device directly to the first portion of the catheter which extends from the handle M, this unit comprising a small boxlike body  101  with a small hollow coupling member  201  at one end, with an axial aperture  2  at the other end, and containing a body  301  made from suitable elastomeric material, having central recessed indentations  3  on its opposite faces and having a diametrically located flat or shaped penetrating slit  4  in the portions where these indentations are present, through which the catheter E can be inserted with a friction fit until the unit  1  reaches the end M 1  of the handle M, as shown by way of example in  FIG. 3 , in such a way that the unit is in contact with a portion of the catheter which executes no bending movements and on which the unit  1  remains in a stable way and in axial alignment as a result of the friction fit. The diameter of the axial cavity of the coupling member  201  and the dimensions of the slit  4  are such that the unit  1  can be positioned on catheters whose outside diameter lies within a wide range of values and on catheters having handles M of any shape or size, thus yielding benefits in terms of practicality and economy. 
     The coupling member  201  terminates in an enlarged edge with a curved profile  201 ′, in such a way that the end of a tube  5 , made from silicone rubber for example and preferably transparent to reveal the passage and movement of the catheter, can be frictionally fitted in a sealed way on to the coupling member, while its opposite end is frictionally connected in a sealed way to a similar coupling member  6  fixed to one end of the telescopic guide  7  which is described more fully below, the whole arrangement being such that, before reaching this guide  7 , the catheter slides in a guided way in the flexible tube  5  which acts as a joint between the unit  1  and the guide  7 , in order to allow greater freedom in the positioning of the catheter handle M and to prevent the direct transmission of small movements, which are imparted to the handle but which are not necessary for the operation of the catheter, to the guide  7  and to the downstream devices or to the patient P, which may occur in the prior art. 
     A further improvement made to the device is that the telescopic guide  7  is made with more than two telescopic sections, for example with three sections as in the example shown in  FIG. 4 , in such a way that, when at rest with the three sections retracted into each other, the guide is shorter than a guide with two sections which have a similar length when extended, since the length in the closed condition is substantially equal to the length of the guide in the extended condition divided by the number of telescopic sections that make up the guide.  FIG. 4  shows that the aforesaid coupling member  6  is fixed to one end of the outer section  107  of the guide  7  and that the coupling extends slightly into this section so as to halt the contraction of the intermediate section  207  which has an outer enlarged area  207 ′ which is halted in the course of extension when it encounters the inner enlarged area  107 ′ of the outer section  107 . The intermediate section is also provided at its other end with an inner enlarged area  207 ″ which acts as a stop on the outer enlarged area  307 ′ of the inner section  307  which has a coupling  8  fixed on its outer end and formed from opposing coupling members, through which the catheter can pass axially, while the other end of the coupling is fixed to the body of the catheter braking unit  9  whose opposite face is fixed to the known adapter  10  which was mentioned in the preamble. 
     Advantageously, the outside diameter of the body of the coupling  8  is such that the distal end of the outer section  107  of the guide  7  can be frictionally fitted on to this body, in such a way that the guide remains stably in the closed position when the device is removed from the packaging, in order to facilitate the application of the device. In the telescopic guide  7  as shown in  FIG. 4 , the inner sections  207  and  307  are mounted in the outer section  107  from the end of this section which is temporarily free of the coupling  6  which is applied and fixed subsequently. When the three sections have been coupled together, the coupling  8  is applied and fixed to the outer end of the section  307 , and thus the guide is substantially formed by at least five parts. However, it is to be understood that the construction of the telescopic guide  7  can be varied and modified in numerous ways without departing from the protective scope of the invention. 
       FIGS. 3 ,  4  and  5  show that the braking unit  9  comprises a body  109  pierced longitudinally by a hole which has, for example, a portion of smaller diameter  11  which can be engaged by one of the end coupling members of the coupling  8 , a tube  13  of suitable plastic material, such as silicone rubber, being initially inserted into the remaining portion  12  of said hole and being stopped by the step formed by the hole  11 , after which the coupling member  110  of the adapter  10  is inserted and fixed. The inside diameter of the tube  13  is made suitably larger than the outside diameter of the catheter. The body  109  has a hole  14  running perpendicularly to the intermediate part of the portion of the hole  12  occupied by the tube  13 , the hole  14  being rotatably engaged by a barrel  15  having a head  115  and a radial lever  215  which remain outside said body  109 . On its lower end the barrel  15  has a recess  16 , in the form of a sector of a circle for example, the generatrix of which is parallel to the longitudinal axis of the lever  215 , such that, when this lever is aligned longitudinally with the guide  7 , as shown in solid lines in  FIGS. 3 ,  4  and  5 , said recess  16  is positioned longitudinally above the tube  13 , substantially without deformation of the latter, while the end appendages  116  of the recess  16  are placed at the sides of the tube  13  and are characterized in that they have suitably rounded edges. 
       FIG. 3  shows that the head  115  of the barrel  15  is provided, laterally and over its whole height, with a flat  17  which reduces its diameter and which, during the assembly of the unit  9 , when the barrel is inserted into its seat  14 , is positioned parallel to and on the same side as a cam  18  in the shape of an L rotated through 90°, which is fixed to the body  109 , in such a way that, when the lever  215  is subsequently rotated into alignment with the holes  11  and  12 , the head  115  of the barrel is positioned under the upper arm of said cam  18 , thus keeping the barrel  15  stably in position. When the barrel  15  has been fitted, a stop pin  19  is positioned and fixed in a suitable seat in the body  109 , said lever  215  bearing on this pin when it is in said longitudinal orientation in which it does not flatten the rubber tube  13 , thus leaving the catheter free to slide through the unit  9  and through the upstream units  1  and  7  and the downstream unit  10 . If the operator rotates the lever  215  through 90°, the lever is positioned under the arm of the cam  18 , which contributes to the axial retention of the barrel  15  in position, since, as a result of this rotation, the lateral appendages  116  of the end recess  16  of the barrel press on the tube  13  flatten it as shown in  FIG. 6 , and this flattening of the tube  13  gently locks the catheter E and prevents it from moving in an undesirable way in relation to all the components of the device in question. It is to be understood that the scope of the invention also covers solutions different from that which has been described for achieving the flattening of the tube  13 , for example the use of rocking control means which, with the assistance of resilient means, enable the position of the barrel or stopping member  15  to be modified in its seat  14 . 
     The adapter  10  is of the type fully described in the prior patents cited in the preamble and is provided with a bayonet fitting  210  for rapid connection to the introduction device I of  FIG. 2  and with an axial nozzle  310 , from which the catheter E emerges by a sliding movement, and which is designed to be coupled to the seal of the introduction device I, which is not illustrated in detail since it is a known means. 
     All the components of the device are made from non-toxic materials, which are compatible with the use for which the device is intended and can be easily sterilized.