Method for the widening of strictures in vessels carrying body fluid
This is a continuation of application Ser. No. 07/933,620, filed on Aug. 21, 1992 now abandoned, which is a continuation of application Ser. No. 07/728,859, filed on Jul. 11, 1991, now abandoned, which is a continuation of application Ser. No. 07/457,216 filed on Dec. 26, 1989, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to dilation catheters in general, and in particular to a catheter device having an insertion catheter, dilation catheter and occlusion catheter in coaxial arrangement. 
     Percutaneous transluminal angioplasty of arteriosclerotic deposits or atheroma in the carotid artery was hitherto regarded as involving risks, since vessel parts detached during dilation might cause a cerebral embolism. In order to reduce the risk of embolism, a catheter device is known in the art which has, in addition to the dilation catheter, a so-called occlusion catheter with which the vessel is for a short time closed downstream. Treatment with this prior art catheter device is awkward, especially since in this case two separate entry points are necessary for the two catheters. Thus, in order to reach the stenosis, two accesses are required in the inguinal region of the patient. 
     A primary object of the present invention is, therefore, to provide a catheter device including an occlusion component which puts less strain on the patient and is easier to handle, and which nevertheless effectively inhibits the occurrence of a cerebral embolism. Another object of the present invention is to provide such a catheter device which provides in coaxial arrangement an insertion catheter, dilation catheter and occlusion catheter which are sealed off with respect to each other and which are individually displaceable in the longitudinal direction. These and other objects will be apparent throughout the description which follows. 
     SUMMARY OF THE INVENTION 
     The present invention is a catheter device comprising an insertion catheter, dilation catheter and occlusion catheter which are sealed off with respect to each other, are arranged coaxially to each other, and are introduced into the blood vessel to be treated through the same entry opening. The catheters are displaceable relative to each other in the longitudinal direction so that, for example, the dilation catheter can be brought into a retracted position. 
     In a preferred embodiment, the insertion catheter has at the distal end an opening which can be in communication with a syringe and through which any vessel particles which have become detached during treatment can be removed by suction or washed out. The removal by suction and washing-out is preferably carried out with the dilation catheter retracted and the occlusion catheter inserted. The occlusion catheter has preferably at its distal end a dilatable latex balloon with which the vessel to be treated can be closed off in the direction of flow following the stenosis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An exemplary embodiment of the invention is described in greater detail below with reference to the drawings in which: 
     FIG. 1 shows a schematic representation of a vessel section with an inserted catheter device according to the prior art; 
     FIG. 2 shows a longitudinal section through a catheter device of the present invention; and 
     FIG. 3a-3f show, in order to illustrate the function of the catheter device, schematic representations of a vessel section and the catheter device. 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     FIG. 1 shows a blood vessel 1 which, downstream from a lateral branch 1a, is partially closed by a stenosis 1b. The known prior-art catheter device shown here has an occlusion catheter 2 having a balloon 2a which can be introduced into the vessel 1 through an insertion catheter 4. Parallel to the insertion catheter 4 and the occlusion catheter 2, a dilation catheter 3 is introduced into the vessel 1 in order to dilate the stenosis. The proximal ends of the dilation catheter 3 and the insertion catheter 4 lead outwards through separate entry points in the inguinal region of the patient. 
     The catheter device of the present invention shown in FIG. 2 has a guide catheter 5 with a flexible catheter tube 5c which has an internal diameter of at least 2 mm. At the proximal end of the catheter tube 5c a connection 5b is arranged for a syringe 5d as shown in FIG. 3e. At the distal end the catheter tube 5c has an opening 5a through which vessel fluid, with any detached particles, can be removed by suction from the area of the stenosis 1b by means of the syringe 5d. 
     The insertion catheter 5 is passed through, in coaxial arrangement, by a dilation catheter 6 having a catheter tube 6a which has a lumen (not shown) and, at the proximal end, a syringe connection for dilating a balloon 6b. The external diameter of the catheter tube 6a is substantially smaller than the internal diameter of the insertion catheter 5c, so that between these two catheters 5 and 6 there is a passage for the fluid drawn off or injected at the inlet opening 5a. 
     The dilation catheter 6 is likewise in turn passed through, in coaxial arrangement, by an occlusion catheter 7. The latter has, at the distal end of a flexible catheter tube 7b, a latex balloon 7a which is connected to a syringe 7c and is filled with an isotonic saline solution as the inflating medium. The catheter tube 7b is preferably of polytetrafluoroethylene and is continuously hollow inside so that there is a connection between the inside of the balloon 7a and the pump 7c. The occlusion catheter 7 has, for example, a length of 250 to 300 cm and at the same time forms a guide for the dilation catheter 6 displaceable upon it. The balloon 7a is a comparatively soft and elastic latex balloon, whereas the dilation balloon 6b in the inflated state has an exactly defined external diameter. 
     At the proximal end of the insertion catheter 5 a seal 5e is arranged, by means of which seal this catheter is sealed off with respect to the dilation catheter 6 in a fluid-tight and displaceable manner. A similar seal 6c is arranged at the proximal end of the balloon catheter 6. Seals of this type are known per se. Also known are connections 6d and 6e on the dilation catheter 6, which are connected to lumina (not shown here) of the dilation catheter. Dilation catheters of this type are likewise well known per se. 
     The individual steps for treating a stenosis 1b in a vessel 1, and in particular in a carotid artery, are illustrated below with references to FIGS. 3a-3f. The insertion catheter 5 is pushed through an opening in the inguinal region of the patient into the vessel 1, until its front opening 5a is situated, as shown in FIG. 3a, directly in front of the stenosis 1b. If appropriate, an exchange catheter (not shown here and known per se) is used in this respect. The proximal end of the insertion catheter 5 is, or course, closed in this respect. The occlusion catheter 7 is now inserted into the guide catheter 5 positioned in this way and is placed distal of the stenosis, and the balloon is stabilized in the inflated state. The dilation catheter 6 is then pushed over the occlusion catheter 7, and the balloon 6b is placed in the middle of the stenosis. Anticoagulants are then injected through the central lumen of the dilation catheter. 
     For the actual treatment of the stenosis 1b, the dilation balloon 6b is now dilated in a known manner. Before dilation, atropine can also be injected through the dilation catheter 6 in order to slow the action of the heart. After treatment of the stenosis 1b the dilation balloon 6b is emptied and the dilation catheter 6 is retracted, as shown in FIG. 3e. With the occlusion catheter 7 simultaneously inflated, vessel fluid 1e and any detached particles 1d present are removed by suction through the insertion catheter 5 by means of the syringe 5d. Since the dilation catheter 6 is retracted in front of the seal 5e, a comparatively wide passage is now available between the catheters 5 and 7. As a result of pressure exerted by means of the syringe 5d, vessel fluid with small detached parts can be rinsed off through this passage in the direction of the arrow 9. The parts thus reach areas of the vessel where there is no danger of embolism. Finally, the balloon 7a is now also returned to the emptied state and the catheter device is removed from the vessel 1.