Abstract:
A system for moving particles suspended in a first fluid, and for infusing them into the stream of a second fluid, includes a catheter with a multi-lumen distal tip. The tip is formed with a plurality of parallel lumens, wherein each lumen has a predetermined diameter. Importantly, the diameter of each lumen is dimensioned to sequentially receive particles therethrough, to prevent the particles from flocculating before they enter the stream of the second fluid. A valve, affixed to the outside of the catheter, can be provided to regulate flow of the second fluid and thereby facilitate entry of the particles into the stream of the second fluid.

Description:
FIELD OF THE INVENTION 
     The present invention pertains generally to infusion systems for introducing particles into a fluid stream. More particularly, the present invention pertains to infusion systems for introducing (infusing) particles of biological matter (e.g. stem cells) into the vasculature of a patient. The present invention is particularly, but not exclusively useful as a system using a multi-lumen filter that allows particles to enter a lumen of the filter either individually or in small groupings, for subsequent infusion into the vasculature of a patient. 
     BACKGROUND OF THE INVENTION 
     An introduction of particles into the vasculature of a patient requires simultaneously satisfying several different concerns or considerations. Depending on the type of particles involved, a concern of significant importance involves preventing the particles from flocculating, i.e. clumping together, as they are being infused or introduced into the vasculature. This is of particular concern in the case of stem cells which can flocculate, but which are most effective in therapy if left to function either as individual cells or in small groups of cells. 
     In all types of intravascular therapy (i.e. intracoronary, intra-arterial or intravenous), it is always an essential concern that the therapeutic agent (e.g. biologics or drugs) be infused or delivered in a predictably controlled manner. Furthermore, it is important that the therapeutic agent be effectively delivered to a proper destination in the vasculature. All of this involves dosage and delivery rate considerations. Moreover, it requires careful handling of the therapeutic agent to insure it (the therapeutic agent) is not damaged or otherwise compromised during an infusion. 
     From a mechanical perspective, it is known that the diameter of a fluid passageway is a factor that will affect the rate of fluid flow through the passageway. For protocols where small groups of de-flocculated particles are to be infused into a vessel of a vasculature, the diameter of the passageway must obviously be large enough to individually accommodate the small groups of particles. On the other hand, it must also be small enough to separate and prevent larger groups of particles (cells) from clinging to each other. A consequence of this is that the rate at which particles can be carried through the passageway will be circumscribed by the dimensions of the passageway. A further consequence of this is that, as particles leave the passageway, they are then influenced by the flow of fluid (i.e. blood) in the vessel of the vasculature. Depending on the purpose of the protocol, this may mean that the downstream fluid flow in the vasculature will somehow also need to be regulated. 
     In light of the above, it is an object of the present invention to provide an infusion system that can effectively introduce only small groups of particles into a fluid flow. Another object of the present invention is to provide an infusion system that coordinates the flow rate of a particle/fluid medium (i.e. a first fluid) with the flow rate of a fluid (i.e. a second fluid) into which the particle/fluid medium is being introduced. Yet another object of the present invention is to provide an infusion system that is easy to use, is simple to manufacture and is comparatively cost effective. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, an infusion system includes an elongated catheter which is formed with a central lumen that extends between the proximal and distal ends of the catheter. Preferably, the catheter is tubular shaped with a smooth circular outer surface and, for purposes of description, the catheter defines a longitudinal axis. A source of a fluid medium having particles suspended therein (i.e. a particle/fluid medium) is connected in fluid communication with the proximal end of the catheter, and a tip (filter) is connected at the distal end of the catheter. For purposes of the present invention, the tip (filter) is provided to prevent the particles from flocculating as they are infused or introduced into a vessel in the vasculature of a patient. As envisioned for the present invention, the particles can be either biologics (i.e. cell, gene or protein) or drugs. And, they can be introduced into the vasculature for intracoronary, intra-arterial, or intravenous therapy. 
     Structurally, the tip is formed with a plurality of parallel lumens. Thus, with the tip affixed to the distal end of the catheter, each lumen of the tip is individually placed in fluid communication with the central lumen of the catheter. Importantly, each individual lumen is dimensioned to sequentially receive only small groups of particles (i.e. less than ten) therethrough. Specifically, although each lumen can receive several particles at a time, each lumen is sufficiently small to effectively separate particles from clinging to each other as they are received into the lumen. It follows that the system also includes a means for moving the particle/fluid medium through the lumen of the catheter, for further movement of the particles in alignment through individual lumens of the tip. For purposes of the present invention the means for moving this particle/fluid medium can be any such means well known in the pertinent art, such as an IV pole, a syringe, or a pump. 
     In addition to the tip (filter) described above, the system of the present invention also includes a configurable (inflatable) valve. Specifically, the configurable valve is positioned on the outer surface of the catheter to surround the catheter at a location that is proximal to the tip. Further, the valve is formed with a plurality of apertures that are arranged around the axis of the catheter. The purpose of these apertures is to control the axial movement of a fluid (e.g. blood) past the catheter in a distal direction substantially parallel to the axis of the catheter. This control is preferably provided by an inflator that selectively constricts the apertures of the valve to control the flow rate of fluid through the apertures. 
     In a preferred embodiment of the present invention, the valve is formed as an annulus that is centered on the axis. With this structure, the annulus has an inner diameter that is affixed to the outer surface of the catheter. The valve also has a substantially non-compliant material positioned on the outer periphery of the annulus that maintains the outer diameter at a predetermined radial distance from the catheter when the valve is inflated into a base configuration. Aside from the non-compliant material, the rest of the annulus is made of a compliant material. Importantly, this compliant material is responsive to the inflator to selectively constrict the apertures. Thus, in operation, an additional inflation of the valve beyond its base configuration substantially maintains the outer diameter at the predetermined radial position, while incrementally constricting the apertures. 
     Additional features of the present invention include a provision for positioning the catheter in the vasculature over a monorail type guide wire. Also, a fluid flow controller can be provided to meter fluid flow from the source into the central lumen of the catheter at a selected fluid pressure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: 
         FIG. 1  is a schematic/perspective view of the system of the present invention shown with the system catheter positioned in an operational environment; and 
         FIG. 2  is a cross-section view of the tip (filter) and distal portion of the system catheter as seen along the line  2 - 2  in  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring initially to  FIG. 1  a system for introducing (infusing) a fluid in accordance with the present invention is shown and is generally designated  10 . As shown, the system  10  includes a catheter  12  that can be advanced into a vessel  14  to position the catheter  10  at a predetermined location in the vasculature of a patient (not shown). For the purposes of the present invention, the vessel  14  is preferably an artery or a vein in the cardiovascular system of a patient, and the system  10  is used for an intra-arterial, intravenous or intracoronary protocol. 
     In detail,  FIG. 1  shows that the system  10  includes a source  16  for holding a fluid medium  18 . As also shown in  FIG. 1 , a plurality of particles  20  are suspended in the fluid medium  18  to create a particle/fluid medium  22 . For the present invention, the particles  20  may be some form of a drug or, most likely, they will be some form of a biologics (i.e. cell, gene or protein). In any event, the particles  20  will be suspended in the particle/fluid medium  22  for transport from the source  16  through the system  10  and into the vessel  14 . As mentioned above for the system  10 , the source  16  can be a syringe of a type well known in the pertinent art.  FIG. 1  also shows that the system  10  includes a controller  24  that is in fluid communication with the source  16 . As envisioned for the present invention, the controller  24  can be any type device that is known in the pertinent art for moving a fluid (e.g. the particle/fluid medium  22 ) through a fluid flow system (e.g. system  10 ). In general, such a device may be an IV pump, an IV pole or some other fluid flow metering apparatus. For an embodiment of the system  10  wherein the source  16  is a syringe, however, there is no specific need for a controller  24 . 
       FIG. 1  also shows that the system  10  includes an inflator  26  for a purpose to be discussed below. When both the controller  24  and the inflator  26  are used for the system  10 , they can be individually joined at a connector  28  to, respectively, establish separate fluid communication channels with the catheter  12 . Preferably, as shown, this connector  28  is connected in fluid communication with the proximal end  30  of the catheter  12 . 
     Still referring to  FIG. 1 , it is seen that the system  10  includes a tip (filter)  32  that is affixed to the distal end  34  of the catheter  12 . Further, it is seen that a valve  36  is mounted on the catheter  12  proximal the distal end  34 , and that the valve  36  is formed with a plurality of apertures, of which the apertures  38   a  and  38   b  are exemplary. The actual construction of the distal portion of the catheter  12 , and the cooperation of structure between the tip (filter)  32  and the valve  36  will perhaps be best appreciated with reference to  FIG. 2 . 
     Referring to  FIG. 2 , and with specific reference to the tip (filter)  32 , it will be seen that the tip (filter)  32  is formed with a plurality of lumens, of which the lumens  40   a ,  40   b , and  40   c  are exemplary. More specifically, the lumens extend axially through the tip (filter)  32  and are substantially parallel to each other. They are also substantially parallel to the axis  42  that is generally defined by the catheter  12 . Importantly, each lumen is established with a diameter  44  that is specifically dimensioned to receive only individual or small groups of particles  20 . Although each lumen can receive several de-flocculated particles  20  at a time, the individual particles  20  or small groups of particles remain separated while they transit the lumen (e.g. see lumen  40   a ). Further, the tip (filter)  32  can be formed with a monorail lumen  46  that will interact with a guide wire  48 , in a manner well known by the skilled artisan, for the purpose of positioning the catheter  12  within the vessel  14 . 
     With the structure of the tip (filter)  32  in mind, as described above, it is an important aspect of the present invention that the diameter  44  of each lumen be dimensioned to prevent the entry of large groups of flocculated particles  20  into the lumen from the central lumen  50  of the catheter  12 . In particular, for different therapeutic protocols, it may be very necessary that the particles  20  be dispersed as they enter the vessel  14 , to thereby minimize the possibility of subsequent flocculation in the vessel  14 . 
     Recall, the valve  36  is formed with a plurality of apertures. Further, with cross reference to  FIG. 1  and  FIG. 2 , it will also be appreciated that, when inflated, the valve  36  is generally shaped as an annulus and is formed with an inflation chamber  52 . As shown, the inflation chamber  52  is connected in fluid communication with the inflator  26  via an inflation line  54 . Within this structure, the inflation line  54  can be integrated into the catheter  12 . For operational purposes, the valve  36  includes a valve body  56  that is made of a compliant, inflatable material. The valve  36  also includes a rim  58  made of a substantially non-compliant material that is located on the periphery of the annulus shaped valve  36 . For the system  10 , the valve  36  is located proximal to the tip (filter)  32 , and it is affixed to the outer surface  60  of the catheter  12  by any means known in the pertinent art, such as by gluing or bonding. 
     Operationally, the valve  36  starts from a deflated configuration, and it is then inflated by the inflator  26  into a base configuration (see  FIGS. 1 and 2 ) wherein the valve  36  is constrained by the rim  58 . In this base configuration, the valve  36  will extend from the surface  60  of catheter  12  through a radial distance  62  and, in the base configuration, it will most likely make contact with the vessel  14 . Also, in the base configuration, each aperture (e.g. aperture  38   a ) will have a diameter  64 . With an additional inflation of the valve  36  by the inflator  26 , however, two different structural consequences occur. For one, the rim  58  does not expand from the base configuration. Thus, the radial distance  62  remains substantially constant. For another, the valve body  56  will expand in response to the inflator  26  such that the apertures are incrementally constricted. Stated differently, and with specific reference to the aperture  38   a , the diameter  64  will be diminished. In an alternate embodiment for the present invention, there may be no need for the valve  36 . 
     For an operation of the system  10  in an intra-arterial, intravenous or intracoronary protocol, a guide wire  48  is first prepositioned in the vasculature of a patient. The guide wire  48  is then received into the monorail lumen  46  of the catheter  12 , and the catheter  12  is advanced over the guide wire  48  and into position in the vasculature of the patient. Once the catheter  12  has been properly positioned, the valve  36  is inflated into its base configuration, or beyond. The exact extent of inflation for valve  36  will depend on the desired flow rate for fluid through the apertures in the vessel  14 . With the valve  36  inflated, the controller  24  is then activated to cause a flow of particle/fluid medium  22  from the source  16  and through the central lumen  50  of the catheter  12 . As particles  20  in the particle/fluid medium  22  arrive at the tip (filter)  32 , the respective diameters  44  of individual lumens in the tip (filter)  32  allow only individual particles  20  or small groups of particles  20  to enter the lumen. Thus, the flocculation of particles  20  in the central lumen  50  is disrupted, and flocculation of the particles  20  after they have passed through the tip (filter)  32  is minimized. Although the above discussion has focused on applications of the system  10  within the cardiovascular system of a patient, the system  10  is appropriate for any use wherein particles  20  may be suspended in a particle/fluid medium  22  for subsequent release as individual particle  20  into a fluid flow (e.g. blood flow through a vessel  14 ). 
     While the particular Biologics Infusion System as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.