Abstract:
The invention relates to a catheter, in particular an endovascular catheter, having an applicator device for liquid active substances for applying same to an active substance storage zone mounted on the catheter.

Description:
FIELD OF INVENTION 
     The invention relates to a catheter, in particular an endovascular catheter, having an applicator device for liquid active substances. 
     BACKGROUND OF THE INVENTION 
     With regard to the background of the invention, it is noted that catheters having so-called drug-eluting stents are known from the prior art in which only solids are used as pharmaceutical active substances. Typical approaches for providing an active substance on or in stents involve incorporation of the active substance into a polymer support, introduction into a porous surface, or integration into active substance depots on the stent. These technical designs are tailored to solids, since for mechanical reasons liquid substances cannot be permanently applied to the stent surface. In addition, compounds in a liquid substance in the stent cause fundamental difficulties with regard to stability under storage. For example, drying phenomena or demixing effects may occur. 
     Approaches to coating medical implants, in particular stents, with liquids are known from US 2006/0124056 A1 or EP 1 325 758 A2. The first-referenced document discloses a device for applying active substances to surfaces of medical implants, in particular stents, composed of a base station and an exchangeable cartridge. A holder for the stents is provided on the cartridge, by means of which the active substances are sprayed via a nozzle onto the surface of the stent. A drive unit is provided on the base station which moves the stent holder and the nozzle relative to one another, the aim being to ensure defined wetting of the stents with liquid active substance. 
     In the second-referenced document, the aim is to improve the dosing accuracy for the liquid medicament on the stent by applying a potential difference between the spray unit and the stent. 
     A problem with the above approaches is that, immediately before placement of the catheter together with the stent, a surgeon must coat the stent with the active substance solution. For this purpose the stent has a porous surface onto which a solution of alcohol and rapamycin, for example, is sprayed. This is a complicated and time-consuming procedure in the surgical environment, in which the dosing of the liquid active substance is very imprecise. 
     SUMMARY OF THE INVENTION 
     On this basis, the feature of the invention is to design a catheter having an applicator device for liquid active substances, such that the latter may be applied to the active substance storage zone in simple process steps and in a short period of time, using a defined active substance dose immediately before the surgical use. 
     This feature is achieved by the features of Claim  1 . Accordingly, the applicator device which surrounds the catheter body in the region of the active substance storage zone with a protective cover has an active substance container, open or to be opened toward the protective cover, with flexible boundary walls on both sides of the active substance storage zone which provide a seal with respect to the protective cover and, after the protective cover is removed, with respect to the catheter body. In this manner the active substance storage zone may be impinged on by the active substance present in the active substance container after the protective cover is removed. The active substance container may be removed from the catheter after a sufficiently long exposure of the active substance storage zone to the active substance liquid. The liquid present in the active substance container is largely retained therein, thus allowing subsequent disposal of the active substance container together with the applicator device. The active substance storage zone on the catheter itself must be provided with an accurately determinable dose of the active substance by impingement over a defined period of time. The entire administration process may be performed very easily and in a comparatively short time, so that the catheter having the applicator device according to the invention is particularly suited for applying the active substance immediately before the surgical use of the catheter. The term “active substance” refers to all pharmaceutically active formulations, such as active substances in pure form, solutions of active substances, etc. 
     The described “active substance storage zone” generally involves the stents, mentioned above in the introductory description, which may be loaded with active substance. In addition, catheters for expanding a stenosis are known in which only the distal end of the catheter together with a balloon provided at that location is guided to the constricted site, and the stenosis is expanded by dilating the balloon. In conjunction with the present invention, the balloon itself, i.e., without a stent resting thereon, may function as an active substance storage zone. 
     The active substance applied immediately before the surgical use is maintained on the stent or balloon in the sense of “storage” until the positioning of the stent or balloon of the catheter is completed. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Preferred refinements of the catheter are stated in the dependent claims. The features, particulars, and advantages thereof are provided in the following description and the exemplary embodiments of the subject matter of the invention, with reference to the accompanying figures, which show the following: 
         FIG. 1  shows a schematic sectional axial view of the distal end of a catheter having an applicator device, in a stored state; 
         FIG. 2  shows an enlarged detailed section according to detail II in  FIG. 2 ; 
         FIG. 3  shows an illustration analogous to  FIG. 1 , in a loading state with the protective cover removed; 
         FIG. 4  shows a schematic axial view of the applicator device in a disposal state, removed from the catheter; 
         FIG. 5  shows an illustration analogous to  FIG. 1  of a catheter having an applicator device, in an alternative embodiment in the stored state; 
         FIG. 6  shows an illustration analogous to  FIG. 5  in an intermediate state, after removal of the protective cover; and 
         FIG. 7  shows an illustration analogous to  FIG. 5  in the loading state, with active substance liquid transferred from the reservoir into the active substance container. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A catheter having an applicator device designated collectively as reference numeral  1  is described in a first embodiment in the stored state, with reference to  FIGS. 1 and 2 . The catheter has an elongated catheter body  2 , of which only the region upstream from the distal end  3  to be inserted into the body of a patient is illustrated. Upstream from this distal end  3  a stent  4  is crimped onto the balloon (not illustrated) of the catheter body  2  in a customary manner, and is covered by a protective cover  5 . The latter is composed of a hose-like main section to which a shrink tubing piece  6  is distally fastened for attachment of a wire  7  in the protective cover  5 . The wire is inserted into a wire lumen (not illustrated in greater detail) of the catheter body  2  to provide sufficient support for the protective cover  5 . The protective cover  5  projects beyond the stent  4  on both sides in longitudinal direction L of the catheter body  2 . 
     The applicator device  1  for a liquid active substance  9  is placed over the protective cover  5 . The integral component of this applicator device  1  is an active substance container  10  which is open toward the protective cover  5 , and which in the form of an annular vessel is provided around the protective cover  5 . The active substance container  10  is mounted on a long, sleeve-like holder  11  which at its proximal end rests on the catheter body  2  by means of a fixation cone  12 . At the distal end the holder  11  is detachably fastened to the protective cover  5  in a suitable manner. 
     At both the proximal and distal ends the active substance container  10  has an annular circumferential, flexible boundary wall  13 ,  14 , which with its radially inwardly facing end face in the form of a sealing lip  15  in each case makes sealing contact with the circumference of the protective cover  5  to prevent entry of liquid. As shown in the enlarged illustration according to  FIG. 2 , the sealing lip  15  of the boundary walls  13 ,  14  may be flexibly bent to improve the sealing contact. 
     In the stored state of the catheter together with applicator device  1  shown in  FIG. 1 , the stent is separated from the active substance  9  in the active substance container  10  by means of the protective cover  5 . After manufacture, the entire device together with the liquid active substance  9  may be sterilized by radiation sterilization, for example. It is important in particular that the activity of the active substance  9  is not impaired by radiation sterilization. 
     To dose the stent  4  with the active substance  9 , during a surgical operation the protective cover  5  is pulled from the catheter body  2  and the applicator device  1  in the distal direction, whereby the boundary walls  13 ,  14 , designed in the manner of a septum, for example, slide along the surface of the protective cover  5  while maintaining a seal. After the protective cover  5  is removed, the boundary walls  13 ,  14  form a seal against the catheter body  2  on both sides of the stent  4 , so that in this loading state, as shown in  FIG. 3 , the active substance  9  is then able to act on the stent  4  and dose same. By use of a stopwatch  8  associated with the catheter together with the applicator device  1  which may be integrated into a surgical setup, for example, a defined time for impingement of the stent  4  with the liquid active substance  9  may be specified. The stopwatch  8  may be automatically started upon removal of the protective cover  5 . An alarm may be generated after the defined impingement time has elapsed. The surgeon then removes the entire holder  11  together with the active substance container  10  from the distal end  3  of the catheter body  2 , whereby the proximal boundary wall  13  wipes the stent  4  and thus entrains excess active substance liquid. 
     As shown in  FIG. 4 , the boundary walls  13 ,  14  are designed in such a way that they provide an outwardly directed seal for the active substance container  10  also after the applicator device  1  is removed from the catheter, thus allowing clean disposal of the liquid active substance  9  together with the applicator device  1 . 
       FIGS. 5 through 7  show one alternative embodiment of a catheter having an applicator device  1 ′. The actual catheter together with the catheter body  2 , stent  4 , and protective cover  5  as well as the basic configuration of the applicator device  1 ′ together with the active substance container  10  and holder  11  are unchanged from the exemplary embodiment according to  FIGS. 1 through 4 . In this regard, matching components are provided with identical reference numerals, and reference may be made to the description for the cited figures. 
     In contrast to the previous exemplary embodiment, the applicator device  1 ′ is provided with a separate reservoir  16  which is designed as a flexible pouch and is closed off by a tearable membrane  17 . The reservoir  16  is connected via a hose  18  to the active substance container  10 , which is still empty in the stored state according to  FIG. 5 . 
     The present configuration allows the active substance  9  to be produced under sterile conditions and then filled into the sterile reservoir  16 . Subsequent sterilization of the reservoir  16  containing the active substance  9  is then no longer necessary, so that radiation sterilization which could possibly impair the active substance may be dispensed with. As a last step, the entire system may be sterilized, for example by gas sterilization using ethylene oxide. It is sufficient to provide the reservoir  16  with a gas-tight design. 
     For dosing the stent  4  with the active substance  9 , in the same manner as for the exemplary embodiment according to  FIGS. 1 through 4  the protective cover  5  is pulled from the applicator device  1 ′, and the sealing lips  15  of the boundary walls  13 ,  14  once again form a tight seal with respect to the catheter body  2 . 
     The pouch-like reservoir  16  is then pressurized by hand, the membrane  17  is torn, and the active substance  9  passes through the hose  18  and into the active substance container  10 , which once again allows the stent  4  to be impinged on by the active substance over a defined period of time. 
     The impingement time may once again be measured using the stopwatch  8  which is schematically indicated in  FIG. 7 . 
     After the impingement time has elapsed, the entire applicator device  1 ′ together with the reservoir  16  is removed from the distal end  3  of the catheter body  2 , analogously to the exemplary embodiment according to  FIGS. 1 through 4 , and the active substance  9  is once again entrained and wiped from the stent  4 . The catheter may then be directly placed, and the stent  4  loaded with active substance may be applied. 
     As indicated by the dashed lines in  FIGS. 5 and 6 , a rigid interior container  20 , for example in the form of a glass ampoule, may also be provided inside the pouch-like reservoir  16  for storing the active substance  9  if the active substance needs to be optimally protected from degradation, for example as the result of a sterilization process using ethylene oxide. The glass ampoule may be broken through the pouch from the outside, causing the active substance  9  to spill into the pouch and also into the active substance container  10 . 
     A filter  21  is provided in the hose  18  so that glass and other particles which may possibly result from breakage of the glass ampoule are retained in the reservoir  16 . 
     It is noted that the active substance container may also be designed as a tubular bag placed around the protective cover in the manner of a ring, whereby the wall of the tubular bag adjoining the protective cover is torn out upon removal of the cover to allow the active substance to access the stent. Lastly, it is noted that the applicator device according to the invention may be used with any type of medical device resting on a catheter, whether it is permanently or temporarily introduced into the body, such as a balloon, for example, for expanding a stenosis, with omission of the actual stent, and the device may thus be loaded with an active substance. This is described by the active substance storage zone characterized in this manner. 
     It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teaching. The disclosed examples and embodiments are presented for purposes of illustration only. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention.