Abstract:
A catheter for the introduction into blood vessels having a lumen and guide means arranged therein wherein the guide means include a pre-bent wire ( 26 ) displaceable in the longitudinal direction of the catheter ( 10 ) and the catheter ( 10 ) has at its distal end an exit lock means ( 38 ) such that the pre-bent wire ( 26 ) can issue from the catheter ( 10 ) through the exit lock means ( 38 ) at the distal end.

Description:
The invention concerns a catheter for the introduction into blood vessels having a lumen and guide means arranged therein. 
     BACKGROUND OF THE INVENTION 
     In this description the term catheter is also used for example to denote an electrode together with electrode line for cardiac pacemakers or defibrillators. A large number of various catheters of the kind set forth in the opening part of this specification are known, which are equipped with various guide means in order to direct a catheter through blood vessels to a desired location. Such catheters or electrodes are known for example from EP 0 667 126, U.S. Pat. Nos. 5,423,884, 5,367,109 or DE 35 107 119. 
     It has been found that known catheters, in particular known cardiac pacemaker electrodes, are scarcely suitable for being introduced for example into the coronary sinus of a heart. There is however the wish to be able also to introduce in particular a cardiac pacemaker electrode into the coronary sinus or blood vessels which involve similar difficulties of access. 
     SUMMARY OF THE INVENTION 
     Therefore the object of the present invention is to provide a catheter which is suitable for introduction into the coronary sinus or other blood vessels which involve difficult access, in particular a cardiac pacemaker electrode line. 
     In accordance with the invention, that object is achieved with a catheter of the kind set forth in the opening part of this specification, in which the guide means include a pre-bent wire displaceable in the longitudinal direction of the catheter and in which the catheter has at its distal end an exit lock means such that the prebent wire can issue from the catheter through the exit lock means at the distal end. 
     The invention is based on the notion of using the pre-bent wire as a probe which can be advanced beyond the tip of the catheter and which, by virtue of the prebent configuration of the wire, faces in a direction which differs from the straight-ahead direction of the catheter. It is possible In that way with the pre-bent wire, to advance into a branch of the blood vessels and to follow with the catheter which is then guided by the pre-bent wire. In this case, the pre-bent wire can be retracted into the catheter again to the same degree as the catheter is advanced so that the tip of the pre-bent wire does not need to execute any relative movement with respect to the blood vessel when the catheter follows along. An exit lock means at the tip of the catheter makes it possible to push out the pre-bent wire without any amount of body fluid worth mentioning penetrating into the catheter. 
     The pre-bent wire is preferably a spring steel wire. It is pre-bent in a helical or spiral configuration at least in the region of its distal end. That manner of pre-bending the wire makes it possible to afford various orientations for the wire, depending on how far the wire is advanced beyond the tip of the catheter. Spring steel wire is suitable for the reason that spring steel can be pre-bent and then the spring action of the spring steel can be straightened out again under the influence of suitable return forces, in which case when those return forces are released, the spring steel wire resumes its pre-bent shape. 
     Preferably the guide means include for the pre-bent wire a guide sleeve or casing which is of such a configuration that it holds the pre-bent wire within the catheter in a straight prestressed condition. The guide sleeve, for example a tube portion, into which the pre-bent wire is inserted, in this case exerts the return forces required for straightening the spring steel wire. When the spring steel wire is advanced out of the tube portion, those return forces which are exerted on the spring steel wire by the tube portion no longer act so that the spring steel wire curves in a configuration corresponding to its pre-bent shape as soon as it issues from the guide sleeve. 
     In this case, the pre-bent wire is preferably adapted to be rotatable relative to the rest of the catheter about its longitudinal axis and is connected to actuating means arranged at the proximal end of the catheter, for rotation of the pre-bent wire. If the pre-bent wire is pre-bent for example in a spiral configuration, it is possible by way of the actuating means to determine the radial direction in which the pre-bent wire is oriented upon being advanced beyond the tip of the catheter. 
     Preferably the catheter has a bar which is of a tubular configuration and which serves as a guide sleeve or casing, having an internal passage in which the pre-bent wire is guided. In that way the bar holds the guide wire oriented in the longitudinal direction of the catheter. The bar is preferably also arranged longitudinally slidably in the catheter and/or rotatably about its longitudinal axis and is connected to actuating means for producing the longitudinal sliding movement and/or the rotary movement of the bar. The pre-bent wire which is guided in the bar can also be rotated in the same way with the actuating means for rotating the bar so that the orientation of the pre-bent wire can be determined by way of the rotary movement of the bar. If the bar is for example in the form of a stylet for screwing in a screw-in tip for an electrode line, the bar and the pre-bent wire can also be adapted to be rotatable independently of each other. 
     Preferably the exit lock means includes a diaphragm or membrane which is to be pierced by the pre-bent wire. In that way the tip of the catheter can remain completely closed by the diaphragm until the pre-bent wire pierces the diaphragm and issues from the tip of the cathode at the front thereof. If the diaphragm comprises elastic material, for example silicone, it closes again when the pre-bent wire is retracted into the catheter again. 
     On its side towards the interior of the catheter the exit lock means preferably has an entrance opening for the pre-bent wire, which opening is of a funnel-shaped configuration. That makes it easier to introduce the tip of the pre-bent wire into the exit lock means. 
     The exit lock means preferably also has an exit opening in the outside of the catheter, which is in the center of a rounded catheter tip at the distal end of the catheter. Due to the central arrangement of the exit opening on the tip of the catheter, the orientation of the catheter itself, upon extension of the pre-bent wire, is irrelevant, the catheter behaves in the same manner in any rotational angular position. The rounded tip of the catheter contributes to the catheter being able to easily follow the pre-bent wire when following same, even in lateral blood vessels which involve a difficult access. 
     The pre-bent wire is preferably coated with gold so that it can be located for example by an X-ray device so that the pre-bent wire can be specifically controlled upon insertion of the catheter. 
     The catheter is preferably in the form of a cardiac pacemaker or defibrillator electrode. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described by means of embodiments with reference to the accompanying drawings in which: 
     FIG. 1 is a diagrammatic outside view of a catheter with pre-bent guide wire, 
     FIGS. 1 a  and  1   b  illustrate the spirally pre-bent and helically pre-bent embodiments of the invention, respectively. 
     FIG. 2 is a view in section through the distal end of a catheter like that of FIG. 1, and 
     FIG. 3 shows the section of FIG. 2 with the pre-bent wire advanced. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The catheter  10  which is illustrated in FIG. 1 is in the form of a cardiac pacemaker electrode with an electrode line  12 , at the distal end of which are arranged ring electrodes  14  and a tip electrode  16 . Also provided at the distal end of the electrode line  12  are tines  18  which can serve as spacer portions or anchoring means for the head of the electrode in the myocardium of a heart. The electrodes  14  and  16  are connected by way of a coiled electrical conductor arranged in the electrode line  12 , to a plug connection  20  which serves for electrically connecting the catheter  10  to a stimulation device such as a cardiac pacemaker or a defibrillator. 
     Also extending in the electrode line  12  is a bar  22  which is of a tubular configuration with a passage extending in the interior of the bar  22 . Extending in the passage is a wire  26  which is pre-bent at its distal end  24 . Both the bar  22  and also the pre-bent wire  26  are respectively connected at their proximal ends to actuating means  28  and  30  which are diagrammatically illustrated in FIG.  1  and with which both the bar  22  and also the pre-bent wire  26  can be displaced relative to each other and relative to the electrode line  12  in the longitudinal direction thereof and rotated about the longitudinal axis thereof. 
     It can already be seen from FIG. 1 that the pre-bent wire  26  can be advanced with its distal end  24  beyond the tip  32  of the catheter  10 . As the pre-bent wire  26  is pre-bent at its distal end  24 , when it issues from the catheter tip  32  it curves into the pre-bend direction. This is a different direction from the extended longitudinal axis of the catheter  10 , in the region of its distal end. 
     Upon insertion of the catheter  10  it can be advanced into the proximity for example of a blood vessel branching. Until then, the pre-bent wire  26  can remain completely retraced into the catheter  10  so that the catheter  10  terminates at its tip  32 . In the proximity of the blood vessel branching the pre-bent wire can then be advanced beyond the tip  32  of the catheter and in so doing is laterally curved in the manner illustrated. By rotation of the pre-bent wire  26  alone or jointly with the bar  22 , it is possible to select the ideal direction in which the pre-bent wire  26  departs from the notional extension of the distal end of the catheter  10  so that the distal end  24  of the pre-bent wire  26  can be introduced exactly into a branching blood vessel. In order to be able to optically follow that procedure outside a body which is to be treated, the pre-bent wire is coated with gold in the region of its distal end. That coating is compatible with the body and makes the pre-bent wire  26  visible by means of an X-ray apparatus. After the pre-bent wire  26  has been sufficiently far advanced with its distal end  24  into a branching blood vessel such as for example the coronary sinus of a heart, the catheter  10  can be followed on, with the pre-bent wire  26  being withdrawn into the catheter  10  at the same time. In that way it is possible for the pre-bent wire  26  not to involve any relative movement which could result in injuries, when the catheter  10  is being further inserted into the blood vessel. 
     The longitudinal section shown in the Figure through the distal end of the catheter  10  shows that distal end before the pre-bent wire  26  is pushed beyond the tip of the catheter  32 . It is possible to see therein ring electrodes  14  and a coiled electric line  34  which serves for the transmission of electrical signals from and to the electrodes  14 . Extending within the coiled electrode line  34  is the bar  22  which is of a tubular configuration and in whose internal passage  36  is guided the pre-bent wire  26 . The pre-bent wire  26  is straightened by the bar  36  so that the pre-bent wire  26  extends substantially straight in the interior of the catheter  10 . 
     As can be seen from FIG. 2, at its distal end the catheter  10  has an exit lock means  38  through which the pre-bent wire  26  can be pushed. At its side towards the interior of the catheter, the exit lock means  38  has an entrance opening  40  of a funnel-like configuration in order to guide the front end of the pre-bent wire  26  into an exit lock passage  42  which adjoins the entrance opening  40 . Provided in the exit lock passage are sealing lips  44  which bear against the peripheral surface of the pre-bent wire  26  when the pre-bent wire  26  is introduced into the exit lock passage  42 . When the pre-bent wire  26  is inserted into the exit lock passage  42 , a condition of sealing integrity is afforded by means of the sealing lips  44 . 
     It can further be seen from FIG. 2 that the exit lock passage  42  is closed in the region of the tip  32  of the catheter by a diaphragm  46  which is pierced when the pre-bent wire  26  is first advanced beyond the tip  32  of the catheter  10 . 
     That condition is shown in FIG.  3 . As soon as the pre-bent wire  26  issues with its distal end  24  from the catheter  10 , it is no longer subjected to forces which straighten it against its pre-stressing, so that the pre-bent wire curves freely in a configuration corresponding to its pre-bend shape. The pierced diaphragm  46  also represents a further sealing lip which, together with the sealing lips  44 , provide for sealing integrity in respect of the interior of the catheter in relation to the exterior thereof.