Abstract:
A multi-component sealant applicator comprises a dual catheter for delivering sealant. Each catheter communicates with one of a pair of fluid sealant agent sources and comprises a mixing volume within the dual catheter for mixing multiple components of a multi-component sealant prior to discharge from a distal end of the catheter and a clearing system to clear undesired material from the mixing volume or the vicinity of the mixing volume, wherein one catheter is mounted for longitudinal movement within the other and the inner catheter is usable as a plunger to remove clogs. The catheter may comprise a reciprocal drive mechanism proximally coupled with the dual catheter to move one catheter longitudinally with respect to the other. The drive mechanism may comprise a ratchet and pawl.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of priority from provisional application Ser. No. 60/102,636 filed Oct. 1, 1998, and entitled “IMPROVED COMPONENT MIXING CATHETER,” the disclosure of which is hereby incorporated herein by reference thereto. This application discloses subject matter in the general field of commonly assigned copending U.S. patent applications Ser. Nos. 08/838,078 and 08/839,614, both filed Apr. 15, 1997, to patent application Ser. No. 08/946,364 filed Oct. 7, 1997, to patent application Ser. No. 09/037,160 filed Mar. 9, 1998 all naming Gordon H. Epstein as first inventor, and to U.S. patent application No. (unknown) filed May 21, 1998 naming Mitchell E. Levinson as first Inventor and entitled “SEALANT APPLICATOR AND METHOD EMPLOYING IMPULSE CLEARING”. The disclosures of the aformentioned United States patent applications, “the above applications” are hereby incorporated herein by reference thereto as is the disclosure of provisional application No. 60/102,636 from which the present application claims priority. Continuation status is not being claimed at this time with respect to the aforementioned non-provisional patent applications. This statement is made without prejudice to applicant&#39;s right to claim continuation status at any time during copendency of the present application with respect to another application. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   (Not applicable.) 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an apparatus and method for applying component parts of a sealant which when mixed transforms from a fluidic state to a non-fluidic state. In particular but not exclusively, the present invention is directed to an apparatus and process in which sealant components are mixed prior to being applied to biological tissue to effect hemostasis or achieve other therapeutic results. 
   2. Description of Related Art Including Information Disclosed under 37 CFR 1.97 and 37 CFR 1.98 
   Use of tissue sealants and other biological materials is an important emerging surgical technique, well adapted for the operating room or field environments such as the doctor&#39;s office or mobile medical units. In addition, the application of such sealants via a catheter provides a non evasive medical technique. Preferred sealants include fibrin sealants which are formed from blood plasma components and comprise, on the one hand, a first component containing fibrinogen and Factor XIII and on the other hand a second component which usually includes thrombin, and calcium ions. 
   The fibrinogen is capable of a polymerizing and being cross-linked to form a solid fibrin clot when the components are mixed. The necessary additional factors to simulate relevant portions of the natural blood coagulation cascade are suitably distributed between the fibrinogen and thrombin components. 
   High levels of protection against transmission of infections or induction of immunological reactions can be assured by using an autologous or single-donor source for both components. Such sealants are highly effective, are biologically degraded without residue and may promote wound healing. 
   Depending upon the potency of the particular formulations employed, coagulation of the sealant may take place very rapidly, yielding a gel within perhaps 10 or 20 seconds after mixing of the two components. Though often very desirable for surgical reasons, such fast-acting properties present potential problems of fouling or clogging. These problems must be overcome in devising suitable applicators, and methods of application. 
   A popular manually operable applicator for such two-component sealants employs a dual syringe construction wherein two syringes, connected by a yoke, each provide a reservoir for one of the components. In most prior devices, the sealant components are discharged in separate streams and mixed externally of the applicator. Such applicators are similar in principle to household epoxy glue applicators commonly available in hardware stores. Achieving effective mixing externally of the applicator is problematic. 
   In U.S. Pat. No. 5, 266,877, and the above applications, the present inventor teaches various constructions of a dual syringe applicator wherein the fluid sealant components are mixed internally. 
   Antanavich et al. U.S. Pat. No. 5,585,007, whose disclosure and references are hereby incorporated herein by reference thereto, provides an extensive discussion of the literature relating to fibrinogen sealant preparation (column 1, line 20 to column 4, line 62) and applicators column 4 line 62 to column 5, line 14), as well as a bibliography, (columns 6-10) and is a helpful guide to the teachings of prior workers in the field. 
   In one or more of the above copending applications the possibility of retrograde clearing of the mixed fluids pathway within the applicator, using suction, is also disclosed. The applicator is provided with suitable suction conduits and valving to apply suction to the work surface, to prepare it for the application of sealant, for example by removing fluids. As taught, the valving is operable to effect retrograde clearing of a sealant dispensing pathway. Enhanced mixing is possible for example, by impingement and problems of fouling by deposited solids are avoided. 
   Such applicators, and methods, are remarkably effective for applying sealants to exposed biological surfaces. However, it would be desirable to provide a surgeon, or other user, with additional choices, for example, an applicator and method that could effectively apply sealant to internal biological locations. 
   One difficulty is that the coagulating nature of the sealants causes the discharge opening or openings of an application device to become clogged so that flow out of the applicator slows down or stops. 
   While the above-referenced copending applications disclose effective clearing-enabled sealant application devices and methods, their techniques are generally intended for application of sealant to exposed and accessible work surfaces. 
   There is accordingly a need for a sealant applicator and method that can be used to reach an unexposed or inaccessible location. 
   SUMMARY OF THE INVENTION 
   The present invention solves this problem by providing a sealant applicator comprising a dual catheter communicating with fluid sealant agent sources, for example, two internal reservoirs, which sealant applicator can effectively deliver multiple sealant components to a remote tip of the catheter for mixing and dispensing to an area of application. Preferably this catheter is a dual catheter having one catheter movably mounted with respect to another, for example longitudinally within the other. The movable catheter is then used as a plunger to unclog the openings. 
   The present invention enables an effective sealant composition to reach an area of application by mixing the sealant components to application or contact with the work surface and providing for removal of coagulated sealant. 
   Preferably, although not necessarily, the sealant is a biological sealant, for example a tissue adhesive, and the area of application is a biological tissue subject to surgery. The sealant components can comprise a first, structural component capable of gelling, and preferably of solidification and a second, activation component which activates such gelling and, optionally, solidification. More preferably, the sealant is a tissue sealant and the first component comprises fibrinogen and the second component comprises, or can generate a fibrinogen activator, especially thrombin or an equivalent thereof. 
   The invention also provides a novel surgical method of applying sealant to unexposed or internal biological surfaces, e.g. human or animal anatomical surfaces, that are accessible to a catheter. The use of a dual catheter, which receives a flow of multiple sealant components and mixes the sealant components at the distal end of the catheter, allows the distal end of the catheter to apply a mixed sealant a work site. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One way of carrying out the invention is described in detail below with reference to the drawings which illustrate one or more specific embodiments of the invention and in which: 
       FIG. 1  is a cross sectional elevational view of a catheter sealant applicator according to the present invention; 
       FIG. 2  is a complete bottom view along lines  2 — 2  of  FIG. 1 ; 
       FIG. 3   a  is a view similar to  FIG. 1  illustrating operation of the applicator of the present invention; 
       FIG. 3   b  is a cross sectional view along the lines  3   b — 3   b  of  FIG. 3   a ; 
       FIG. 3   c  is a cross sectional view of an alternative embodiment of the present invention; 
       FIG. 4  is a cross sectional elevational of an alternative embodiment of the present invention; 
       FIG. 5  is a cross sectional view illustrating operation of the present invention; 
       FIG. 6  is a cross sectional view illustrating operation of the present invention; 
       FIG. 7  is a cross sectional view illustrating operation of the present invention; 
       FIG. 8  is a cross sectional view illustrating operation of the present invention; 
       FIG. 9  is a perspective view of a component part of the present invention; 
       FIGS. 10 and 10   a  are a cross sectional view illustrating an alternative embodiment of the present invention; 
       FIGS. 11 and 11   a  are a cross sectional view illustrating an alternative embodiment of the present invention; 
       FIG. 12  is a cross sectional view illustrating an alternative embodiment of the present invention; 
       FIG. 13  is a cross sectional view illustrating an alternative embodiment of the present invention; 
       FIG. 14  is a cross sectional view illustrating an alternative embodiment of the present invention; 
       FIG. 15  is a cross sectional view illustrating an alternative embodiment of the present invention; 
       FIG. 16  is a perspective view of a further embodiment of the invention employing a plug-like inner catheter, in a retracted position within an outer catheter shown as being transparent to reveal the inner structure; and 
       FIG. 17  is a view similar to  FIG. 16  with the plug-like inner catheter in an advanced position. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to  FIGS. 1 and 2 , a sealant applicator  10  is illustrated. Applicator  10  comprises a pair of inner and outer coaxial catheters  12  and  14 . In the preferred embodiment inner and outer catheters  12  and  14  are elongated tubes. Inner and outer catheters  12  and  14  are constructed out of any suitable, preferably sterilizable material, for example, stainless steel or polypropylene, and may be rigid or flexible, or may comprise both rigid and flexible components along their lengths. Typically, catheters are substantially longer than the dispensing cannulas described in preferred embodiments of the parent application, having, for example, a length of at least 10 cm, often at least 20 cm and sometimes being substantially longer, for example a meter or more. Commonly, catheters are flexible, or have a flexible portion. 
   Inner catheter  14  defines an area  16  and is of a smaller diameter than outer catheter  12 , this allows outer catheter  12  to surround inner catheter  14  leaving a second area  18 . 
   Outer catheter  12  is configured to have an opening  20  for dispersing a mixed sealant  22 . 
   Sealant  22  is typically comprised of a first sealant agent or component  24  and a second agent or component  26 . Component  24  is contained within area  16  and component  26  is contained with area  18 . Inner catheter  14  has an opening  28  for discharge of component  24 , and in the position shown in  FIG. 1  is retracted behind opening  20  of outer catheter  12  to provide a mixing volume  29 . 
   In the preferred embodiment areas  16  and  18  and their respective ratios are of such a configuration as to provide desired proportions of components  24  and  26  to provide a sealant  22  in accordance with the required parameters. As may be desired, areas  16  and  18  and their corresponding volumes may be varied to provide a sealant  22  of various characteristics. For instance, a sealant that may require a longer time to cure or a sealant that may require lesser time to cure by using a lesser or greater proportion or concentration of activator, e.g. thrombin for a fibrinogen sealant. 
   Areas  16  and  18  are of sufficient size to allow for unimpeded flow of the sealant components. 
   Inner catheter  14  is slidably or otherwise movably mounted with respect to outer catheter  12  to permit relative movement of inner catheter  14  in the directions of arrow  30 . 
   The movement of outer catheter  12  allows opening  28  of inner catheter  14  to be positioned within outer catheter  12  and away from opening  20 . This position allows components  24  and  26  to mix in an area in close proximity to opening  20 . Moreover, and as illustrated in  FIG. 3a , the position of opening  28  may be further retracted with respect to outer catheter  12 . This positioning will provide a larger mixing volume  29  allowing for a longer mixing time of component  24  and  26 . 
   Alternatively, opening  28  may be positioned closer to opening  20 , if desired, to reduce the volume of mixing volume  29  and the time components  24  and  26  are in contact with each other inside applicator  10 . This may be appropriate for a very fast setting sealant. 
   To stabilize inner catheter  14  and maintain the appropriate mixing volumes of components  24  and  26 , a stabilizing ring  27  (as illustrated by the dashed lines in  FIG. 3   a ) or the equivalent thereof can be affixed to inner catheter  14  and extend outwardly to outer catheter  12 . Stabilizing ring  27  provides stability to inner catheter  14  and is configured to allow component  26  to flow through the same. 
   Alternatively, and depending on the length of catheters  12  and  14 , a plurality of stabilizing rings  27  may positioned within applicator  10  to provide stability to inner catheter  14 . 
   The movement of inner catheter  14  may be effected by any suitable mechanism for example, a proximally located ratchet and pawl mechanism as illustrated in FIG.  4 . In this embodiment a locking mechanism  32  restricts the movement of the proximal end of inner catheter  14  by engaging with a plurality of nubs  34 . Movement of mechanism  32  into a position, as illustrated by the dashed lines in  FIG. 4  will once more allow inner catheter  14  to move in the direction of arrow  30 . Mechanism  32  may be configured to have a conveniently placed trigger to facilitate the release. 
   In addition, and as an alternative, mechanism  32  can work in conjunction with a return spring  39  which is depressed as inner catheter  14  is depressed. Accordingly, as mechanism  32  is released the force of spring  39  acts to return inner catheter  14  to its original position. 
   Optionally, inner catheter  14  may be provided with graduated markings  36 . Markings  36  can indicate the relative position of opening  28  of inner catheter  14  with respect to opening  20  of outer catheter  12 . For instance, a marking of zero would indicate that opening  28  and opening  20  are flush with each other. Other markings such as +1,+2,+3, or −1, −2, −3 would indicate the respective location of opening  28  with respect to  20 . 
   In yet another embodiment markings  36  can indicate the flow output of sealant  22  depending on the position of opening  28 . Depending on the size of catheters  12  and  14 , markings  36  can be configured to indicate flow output of mixed sealant  22 , such as millimeters per second or any other suitable indicator of flow output. In addition, markings  36  may also be configured to refer to the mixture ratio of component  24  with respect to component  26 . 
   The movement of inner catheter  14  with respect to outer catheter  12  also allows a user to conveniently purge any clot of hardened sealant  22  from opening  20 , as will now be further explained. 
   Turning now to  FIGS. 5 and 6 , and as previously discussed the internal mixing of components  24  and  26  effects coagulation of sealant  22 . However, such coagulation may cause a clot  38  to block opening  20 . This problem is addressed by the mobility of inner catheter  14 . To facilitate the removal of clot  38  the user can simply move inner catheter  14  to the position illustrated in FIG.  6 . Such movement may be accomplished through the use of a trigger mechanism as described with reference to  FIG. 4 , or any other suitable mechanism. 
   In yet another embodiment stabilizing ring  27  ( FIGS. 3   a  and  3   b ) is also used as a plunger for removal of clot  38 . In this embodiment stabilizing ring  27  is slidably mounted in area  18  positioned between inner catheter  14  and outer catheter  12 . Movement of ring  27  is effected through the use of a user manipulated trigger mechanism. To remove clot  38  the user simply causes ring  27  to move towards opening  20 . Such movement will dislodge clot  38 . As an alternative, a plurality of stabilizing rings  27  may be positioned throughout area  18 . 
   Stabilizing ring  27  allows component  26  to flow through area  18  unimpeded, however, stabilizing ring  27  is constructed in such a manner as to force clot  38  from opening  20  once stabilizing ring  27  has made contact with clot  38 . 
   One such configuration is that of a spoked wheel ( FIG. 3   b ) wherein the spokes  33  of stabilizing ring or rings  27  define a plurality of openings  35 . Openings  35  are large enough to allow component  26  to pass through while being small enough to force the removal of clot  38 . 
   Alternatively, ring or rings  27  is a disk having a plurality of smaller openings  35  ( FIG. 3   c ). 
   Movement of stabilizing ring  27  is effected through the use of a trigger mechanism, such as a plunger or the equivalent thereof, positioned at the proximal end of applicator  10  which is conveniently accessed by the user&#39;s finger or thumb. 
   In yet another embodiment, ring or rings  27  are secured to inner catheter  14 . Thus, as the user manipulates or moves inner catheter  14  ring  27  also moves. 
   In a still further embodiment, rings  27 , or inner catheter  14  with rings  27  secured to it, are capable of being rotated as they are being depressed. Such rotation will enhance the dislodging of clot  38 . 
   Other clot removal techniques such as those illustrated in  FIGS. 7 and 8  may be utilized. In this sequence, a user first moves inner catheter  14  into the position illustrated in FIG.  7 . The movement will dislodge clot  38  from opening  28  of inner catheter  14 . Then the user moves inner catheter  14  into the position illustrated in FIG.  8 . This movement allows inner catheter  14  to act as a plunger which will dislodge clot  38  from opening  20  thereby discharging clot  38  from applicator  10 . 
   Alternatively, and as illustrated by the dashed lines in  FIG. 8 , catheters  12  and  14  may be constructed out of a flexible material capable of being manipulated into the squeezed position illustrated by the dashed lines. This configuration allows the distal end of applicator  10  to be compressed to dislodge clot  38 . In addition, small amounts of components  24  and  26  will be forcibly dispelled during this compression and will aid in the clearing of applicator  10 . The manipulation of applicator  10  can be performed by the fingers of the user or a pinching mechanism which could be hand held or adhered to applicator  10 . 
   Alternatively, catheters  12  and  14  may be constructed out of a flexible material capable of be manipulated at the proximal end of applicator  10  to effectively pinch off the supply of components  26  and  24 . The compression of catheters  12  and  14  at the proximal end also causes small amounts of components  24  and  26  to be discharged. Such placement of a pinching mechanism or pinching capability at the proximal end of applicator  10  also provides for an ergonomic device. 
   Openings  28  and  20  may be equipped with a closing mechanism, such as a removable cover  31  (illustrated in  FIG. 9 ) which prevents unrestricted flow of components  24  and  26  from inner and outer catheters  12  and  14  between uses. 
   Referring now to  FIGS. 10 and 10   a  an alternative embodiment of the present invention is illustrated. In this embodiment, components and/or parts performing analogous or similar functions are numbered in multiples of  100 . Here an opening or plurality of openings  128  are positioned along the elongated portions or walls of catheter  114 . These openings allow component  124  to mix with component  126  throughout an extended mixing volume  129  prior to discharge of mixed sealant  122  from opening  120 . This embodiment allows for a particularly effective mixing of components  124  and  126  prior to application. 
   In this embodiment the end of catheter  114  is closed. Accordingly, mixed sealant  122  is applied to the required location through opening  120 . Catheter  114  may also be positioned to apply sealant  122  as illustrated in  FIGS. 11 and 11   a.    
   In the case where a clot  138  has blocked opening  120 , catheter  114  may also be used as a plunger to remove clot  138  (as illustrated by the dashed lines in  FIG. 11   a ). 
   In yet another embodiment, and as illustrated in  FIG. 12 , catheter  214  is configured to have a plurality of smaller openings  228  throughout a selected length of the distal end of the catheter  214 , for example 1 or 2 cm., or the entire surface of catheter  214 . This configuration allows for an even greater mixing volume  229 . Preferably, sufficient pressure of sealant agent or component is maintained in inner catheter  214  to ensure avoid possible backflow and clogging of openings  228  owing to mixing of the sealant components in the openings. 
   In addition and in order to aid in the clot expulsion as depicted in  FIGS. 6-8  small amounts of components  24  and  26  may also be expelled with the clot to ensure that all of the clot is removed from applicator  10 . 
   Referring now to  FIG. 13 , one possible supply connection of inner and outer catheters  12  and  14  is illustrated. A flexible connector  14   a  is connected to the proximal end of inner catheter  14 . Flexible connector  14   a  supplies area  16  with sealant component  24 . The flexible nature of connector  14   a  allows inner catheter  14  to move in the directions of arrow  30 . 
   Movement of inner catheter  14  is facilitated by the manipulation of an actuating mechanism  40  which is secured to inner catheter  14  via a clamping device  42 . Such manipulation causes a corresponding movement of inner catheter  14 , and may be effected by a manual control (not shown), for example a spring-loaded depressible button or trigger. 
   A flexible gasket  44  allows for movement of inner catheter  14  while providing a secure seal around catheters  14  and  12 . 
   Outer catheter  12  is also connected to a connector  12   a . Connector  12   a  supplies area  18  with sealant component  26 . Connector  12   a  may also be flexible, however connector  12   a  may be constructed out of a more rigid material. 
   Referring now to  FIG. 14  yet another alternative embodiment of the supply connection of the present invention is illustrated Here both inner and outer catheters  314  and  312  are connected to connectors  312   a  and  314   a . In this embodiment catheter  312  is configured to have a flexible and expansible portion  346 , which can, for example, be of fanfold or accordion-like bellows construction and is located intermediate to catheter  312  and connector  312   a . Flexible portion  346  allows for constriction and expansion of outer catheter  312  in the directions depicted by arrow  330 . Movement of catheter  312  is effectuated by an actuating mechanism  340 . As mechanism  340  advances or retracts catheter  312  also moves in the same direction. 
   Referring now to  FIG. 15  an alternative embodiment of the distal, delivery end of applicator  10  is illustrated. Here catheter  12  is configured to have a tapered end, constricting the flow of sealant components to provide a mixing volume  29  with strong turbulence. The outer diameter of inner catheter  14  can be as large as opening  20 , thus when inner catheter  14  is advanced, it exerts a precise plug-removal clearing action on the reduced diameter tip of outer catheter  12 . 
   The embodiment of the invention shown in  FIGS. 16-17 , comprises a modified clearing-enabled, dual catheter sealant applicator  360  which can be fabricated from suitably soft or resilient materials, to have a flexible or malleable end or tip  362  to facilitate or enhance engagement of the applicator with, and entry of the applicator into, living tissues, for example, the ear, the nose or the throat. The material of applicator  360 , at least at tip  362 , should preferably be sterilizable and non-absorbent, as well as soft, or deformable, and resilient, and may for example, be a silicone rubber. 
   Catheter sealant applicator  360  comprises a hollow outer sheath  364 , an inner plug  366  which has an axial bore  368  and external channels  370 , and a supply lumen  372  press-fitted into plug  366 . As shown, four symmetrically disposed channels  370  are provided, but other numbers of channels  370  such as three, six or eight may be employed. The outer diameter of plug  366  is a close sliding fit within the inner diameter of sheath  364 . The cross-sectional areas of channels  370  and bore  368  are selected to provide desired relative flow rates of sealant agents, which relative flow rates may be varied, or selected, by using plugs  366  of different configurations. Such diverse plugs  366  may be supplied each with a lumen  372 , or may be interchangeably fittable to one or more lumens  372 . Optionally, channels  370  on plug  366  can taper outwardly, in the fluid delivery direction, which is to say distally, to increase the channel area in the direction of flow and facilitate clearing and the removal of clots. 
   A further option is for channels  370  to have a helical configuration, as shown, simulating rifling, to impart spin to the fluid travel to enhance mixing of the sealant agents. In such case a still further option is for channels  370  to be twisted in opposed directions around plug  366 , to impart countercurrent flows and further enhance mixing. 
   Preferably, the sealant catalyst, for example, in the case of a fibrinogen sealant, thrombin or other fibrinogen activator, is supplied through lumen  372  to bore  368  in plug  366 , and fibrinogen or other polymerizable sealant agent, is supplied in the space between the outside of the lumen and the inside diameter  374  of sheath  364 . 
   For application of sealant, the forward or distal face of plug  366  is slightly retracted behind the distal end of sheath  364  to allow mixing of the two agents to take place in a mixing volume disposed generally within the sheath  364 . As with other embodiments described herein, significant mixing of the sealant components takes place before delivery of the sealant agents to, or contact of the sealant agents with, the target work surface. 
   Once a cycle of sealant application is complete, tip  362  can be cleared of any clot or other material, by advancing lumen  372 , driving plug  366  forwardly inside sheath  364  and expelling the clot. If necessary, the clot can be freed from the face of plug  366 , or loosened, by dispensing a small amount of sealant. 
   The invention provides a novel surgical method of applying sealant to unexposed or internal biological surfaces, e.g. human or animal anatomical surfaces, that are accessible to a catheter, for example, inner ear structures, the veins and arteries and organs such as the heart that are accessible via veins and arteries, the bladder, and so on. The method comprises use of a dual catheter such as described hereinabove, which is coupled to a sealant applicator to receive a flow of multiple sealant components from the applicator and to mix the sealant components at the distal end of the catheter, and insertion of the catheter into a body organ to advance the distal end of the catheter to a work site, operation of the sealant applicator to dispense sealant from the distal end of the dual catheter, and removal of the dual catheter from the body organ. After removal, the tip of the dual catheter will usually be cleared of any clog by operating the inner catheter as a plunger and ejecting the clog to waste. In an exceptional case, and with due care on the part of the surgeon or other operator, the inner catheter may be advanced while the dual catheter is inserted into a body organ, to free the dual or outer catheter, or clear and obstruction or, possibly, to manipulate the work surface. 
   While illustrative embodiments of the invention have been described above, it is, of course, understood that various modifications will be apparent to those of ordinary skill in the art. Many such modifications are contemplated as being within the spirit and scope of the invention.