Abstract:
A closed loop catheter useable for heat exchange is manufactured by forming a plurality of generally transverse bore holes though a flexible, multilumen catheter body, lacing a tube trough the bore holes so that loops of the tube protrude from the catheter body, connecting one end of the tube to an inflow lumen of the catheter and connecting the other end of the tube to an outflow lumen of the catheter. A heated or cooled heat exchange medium may then be circulated through the tube while the catheter is inserted in the vasculature of a subject, thereby resulting in heat exchange between the subject&#39;s flowing blood and the heat exchange medium being circulated through the tube.

Description:
RELATED APPLICATION 
     This patent application claims priority to U.S. Provisional Patent Application No. 61/542,004 filed Sep. 30, 2011, the entire disclosure of which is expressly incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to medicine and biomedical engineering and more particularly to heat exchange catheter devices and their methods of manufacture and use. 
     BACKGROUND OF THE INVENTION 
     Pursuant to 37 CFR 1.71(e), this patent document contains material which is subject to copyright protection. The copyright owner has no objection to facsimile reproduction of the entire patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
     Hypothermia can be induced in humans and some animals for the purpose of protecting various organs and tissues (e.g., hear, brain, kidneys) against the effects of ischemic, anoxic or toxic insult. For example, animal studies and/or clinical trials suggest that mild hypothermia can have neuroprotective and/or cardioprotective effects in animals or humans who suffer from ischemic cardiac events (e.g., myocardial infract, acute coronary syndromes, etc.), postanoxic coma after cardiopulmonary resuscitation, traumatic brain injury, stroke, subarachnoid hemorrhage, fever and neurological injury. Also, studies have shown that whole body hypothermia can ameliorate the toxic effects of radiographic contrast media on the kidneys (e.g., radiocontrast nephropathy) of patients with pre-existing renal impairment who undergo angiography procedures. 
     One method for inducing hypothermia is by endovascular temperature management (ETM) wherein a heat exchange catheter is inserted into a blood vessel and a thermal exchange fluid is then circulated through the heat exchange catheter. This technique can effectively cool blood flowing through the subject&#39;s vasculature and, as a result, lower the core body temperature of the subject to some desired target temperature. ETM is also capable of warming the body and/or of controlling body temperature to maintain a monitored body temperature at some selected temperature. If a controlled rate of re-warming or re-cooling from the selected target temperature is desired, that too can be accomplished by carefully controlling the amount of heat added or removed from the body and thereby controlling the temperature change of the patient. 
     A number of heat exchange catheters are currently available for use in ETM. One such catheter, the SoIex™ Catheter available from ZOLL Circulation, Inc. of Sunnyvale, Calif., generally comprises a flexible catheter shaft having curved loops of tubing protruding from opposite sides of a distal portion of the catheter. In operation, the distal portion of the Solex™ catheter is inserted into the vasculature of a subject and a heated or cooled thermal exchange medium is then circulated through the curved loops of tubing. This results in exchange of heat between the circulating thermal exchange medium and blood flowing through the subject&#39;s vasculature, without causing the thermal exchange medium to be infused into the subject&#39;s bloodstream. 
     The current Solex™ catheter is formed of two subassemblies, a proximal portion and a distal portion. The proximal portion is a dual lumen tube that has an inflow lumen through which the thermal exchange fluid flows in the distal direction and an outflow lumen through which the thermal exchange fluid flows in the proximal direction. The distal portion is a coiled shaft with thin walled tubing “sewn” onto it to form the protruding curved loops of tubing. These proximal and distal portions are then joined together to make the final catheter. This two-piece construction requires a jointure or connection midway along the catheter shaft and is relatively labor intensive. 
     Additionally, the coiled shaft on the distal portion of the Solex™ catheter gives rise to a “bumpy” feel as the catheter is withdrawn through a vascular introducer, such as during removal of the catheter from the subject&#39;s body. The elimination of the coiled distal shaft in favor of a smoother one-piece shaft could lessen or eliminate such “bumpy” feel as the catheter is being removed from the patient. 
     Accordingly, there exists a need in the art for the development of new methods for catheter manufacture that may be used for the manufacture of the Solex™ catheter and/or other catheters having similar construction, thereby eliminating the need for formation of a jointure or connection midway along the catheter shaft and potentially offering other advantages, such as; 1) reducing the number of parts used in manufacturing the catheter and/or 2) reducing the labor and manual endeavor required for manufacture of the catheter, such as eliminating the need for the delicate sewing step to attach the thin-walled tubing to the coiled shaft and/or 3) reducing or eliminating the “bumpy” feel that the catheter has when being removed from the patient. 
     SUMMARY OF THE INVENTIONS 
     In accordance with the present invention, there is provided a catheter device having a one-piece or unitary catheter shaft with protruding loops of tubing which form a closed-loop recirculation circuit through which thermal exchange fluid or other flowable matter may be circulated. 
     Further in accordance with the present invention, there is provided a catheter device comprising: a) an elongate catheter body having, a proximal end, a distal end, an inflow lumen and an outflow lumen; b) a plurality of bores extending transversely through the catheter body at spaced-apart locations; c) a tube having a first end connected to the inflow lumen and a second end connected to the outflow lumen, said tube passing in alternate transverse directions through adjacent ones of said bores such that tubing loops comprising portions of said tube protrude outwardly from opposite sides of the catheter body. 
     Still further in accordance with the present invention, there is provided a method for manufacturing a catheter device, said method comprising the steps of: a) providing or obtaining an elongate catheter body having, a proximal end, a distal end, an inflow lumen and an outflow lumen; b) forming a plurality of bores transversely through the catheter body at spaced-apart locations; c) passing a tube in alternate transverse directions through adjacent ones of said bores such that loops of the tube protrude outwardly from opposite sides of the catheter body; d) connecting a first end of the tube to the inflow lumen; and e) connecting a second end of the tube to the outflow lumen. The bores may be formed by any suitable means such as drilling, punching, laser cutting, blade cutting, water jet cutting, or other manual or automated techniques known in the art. In some embodiments, the bores may be formed by advancing a punch through the catheter body at an angle (e.g., substantially a right angle or any other desired angle) relative to a longitudinal axis of the catheter body. If oval or ovoid bores are desired, such punch may be of oval or ovoid shape. 
     Still further aspects and details of the present invention will be understood upon reading of the detailed description and examples set forth herebelow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an endovascular temperature management system of the present invention. 
         FIG. 2  is a partial perspective view of a portion of a catheter body having a plurality of transverse bores formed therein during manufacture of a catheter device of the present invention. 
         FIG. 3  is a partial perspective view of the catheter body portion of  FIG. 2  having a tube passed in alternating directions through the transverse bores such that loops of the tube protrude on opposite sides of the catheter body during manufacture of a catheter device of the present invention. 
         FIG. 3A  is a transverse cross sectional view through line  3 A- 3 A of  FIG. 3 . 
         FIG. 3B  is a transverse cross sectional view through line  3 B- 3 B of  FIG. 3 . 
         FIG. 3C  is a transverse cross sectional view through line  3 C- 3 C of  FIG. 3 . 
         FIG. 4  is a side view of a fully assembled catheter device of the present invention. 
         FIG. 4A  is a distal end view of the catheter device of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description and the accompanying drawings to which it refers are intended to describe some, but not necessarily all, examples or embodiments of the invention. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The contents of this detailed description and the accompanying drawings do not limit the scope of the invention in any way. 
       FIG. 1  is a schematic diagram of an endovascular temperature management system  10  which comprises a heat exchange catheter  12  of a type having heat exchange tubing loops  14 , an extracorporeal control console C and at least one body temperature sensor TS. In this example, the extracorporeal console C contains a controller (e.g., a microprocessor controller), a user interface UI for inputting data to the controller, a heater/cooler for adjusting the temperature of a thermal exchange medium (e.g., 0.9% sodium chloride solution) and a pump for pumping the thermal exchange medium. 
     The catheter  12  is connected to the extracorporeal console C by way of an inflow line IL and an outflow line OL so that the pump within the console C will circulate temperature-controlled thermal exchange medium through heat exchange tubing loops  14  which protrude from a distal portion of the heat exchange catheter  12 . In operation, the catheter  12  is inserted into the vasculature of a subject so that blood flowing through the subject&#39;s vasculature will pass over and in heat exchange proximity with the heat exchange tubing loops  14 , thereby allowing heat to be exchanged between the circulating thermal exchange medium and the subject&#39;s flowing blood. Warming or cooling of the subject&#39;s flowing blood then results in warming or cooling of all or a desired portion of the subject&#39;s body. In the particular non-limiting example shown in  FIG. 1 , the distal portion of the catheter  12  is positioned so that the heat exchange tubing loops  14  reside within the subject&#39;s inferior vena cava IVC, such catheter positioning being suitable for applications wherein whole body temperature management is desired. 
     The temperature sensor(s) TS may be positioned on or in the subject&#39;s body to measure the temperature of all or part of the body where it is desired to effect temperature modification or control. The controller within the console C receives signals from the temperature sensor(s) TS indicating the currently sensed body temperature. A desired target temperature may be input via the user interface UI and the controller will then issue control signals to the heater cooler and/or pump to adjust the temperature and/or the flowrate of the heat exchange medium in an effort to attain and/or maintain the target body temperature. A control console of the type shown in  FIG. 1  and described in this example is commercially available as the Thermogard XP™ Temperature Management System from ZOLL Circulation of Sunnyvale, Calif. Other potentially useable control consoles are available from other sources and/or described in the following United States patents and published patent applications, the entire disclosures of which are expressly incorporated herein by reference: 
     The catheter  12  of this example is constructed and manufactured in the manner shown in  FIGS. 2-4A . A one-piece catheter body  12  is used in this example. As may be appreciated from the cross-sectional views of  FIGS. 3A-3C , the catheter body  12  of this example has an inflow lumen  17 , an outflow lumen  15 , an optional distal infusion or guidewire lumen  16 , an optional medial infusion lumen  18  and an optional proximal infusion lumen  19 . The individual lumens  15 ,  16 ,  17 ,  18 ,  19  may be integrally formed (e.g., extruded) within the catheter body  12  or may comprise one or more separate tube(s) that are passed through a lumen of the catheter body  12 . In this particular example, the one-piece catheter body is formed of an extruded multilumen tube. Also, in this example, the catheter body  12  has an optional atraumatic distal tip member  11  attached to its distal end. 
     At the time of manufacture, a series of transverse bores  13  are formed through the catheter body  12 , as shown in  FIG. 2 . These transverse bores  13  may be formed at any suitable angle relative to the longitudinal axis LA of the catheter body  12 . In the particular example shown, the bores  13  are oval or ovoid shaped bores formed by advancing an oval or ovoid shaped punch through the catheter body  12  on a predetermined trajectory and such bores extend through the catheter body  12  substantially at right angles relative to the longitudinal axis LA of the catheter body  12 . The trajectory of the bores  13  will avoid obliteration of any lumen(s) that are required to remain in tact to carry apparatus or thermal exchange media through that portion of the catheter body  12 . In this example, optional medial infusion lumen  18  and optional proximal infusion lumen  19  are terminally sealed to proximal and medial infusion lumen outlet openings  44 ,  46  (seen on  FIG. 4 ), which are located proximal to where the bores  13  are formed. Therefore, the medial and proximal infusion lumens  18 ,  19  are nonfunctional in the region where the bores  13  are formed. Also, in this example, the outflow lumen  15  is terminally sealed to the proximal end of tube  14  at window  20 . Thus, the portion of outflow lumen  15  that extends through the region where the bores  13  are formed is non-function. Thus, in this example, the positioning of the catheter body  12  and the trajectory of the punch are controlled so that each bore  13  only obliterates unused portions of the outflow lumen  15 , optional medial infusion lumen  18  and optional proximal infusion lumen  19 , while leaving the inflow lumen  15  and optional distal infusion or guidewire lumen  16  in tact. 
     The catheter body  12  may be appropriately sized and formed of any material(s) suitable for the intended applications of the catheter device. For example, in many applications, it will be desirable for the catheter body  12  to have enough rigidity and wall thickness to contain working pressures of up to about 100 psi while being sufficiently flexible to navigate through the intended blood vessels or other body lumens to the desired location within a subject&#39;s body. Typically, this may be accomplished by a catheter body that has an outer diameter of 6 Fr (0.080″) to 14 Fr (0.180″) and is formed of a biocompatible polyurethane (e.g., Elastollan™ available from BASF Corporation, Florham Park, N.J. or Tecothane™ available from The Lubrizol Corporation, Wickliffe, Ohio) or polyether block amide (e.g., Pebax™ available from Arkema, Inc., Philadelphia, Pa.). 
     The heat exchange tube  14  may be appropriately sized and formed of any material(s) suitable for the intended applications of the catheter device. For example, in many applications, it will be desirable for the heat exchange tube  14  to a) have a thin wall thickness (typically around 0.001″) to best facilitate heat transfer, b) have sufficient tensile strength to withstand pressures of up to about 100 psi and c) be sufficiently rigid or semi-rigid so as not to expand uncontrollably under pressure. Thus, it will be desirable for the tube  14  to be formed of a material capable of being extruded and/or blown into a tube having such wall thickness and properties. Examples of materials that may be suitable for forming the tube  14  include polyethylene terephthalates (PETs) available from a variety of sources or polyether block amide (e.g., Pebax™ available from Arkema, Inc., Philadelphia, Pa.). 
     Also, as seen in  FIG. 2 , a window into the inflow lumen  22  is skived or otherwise formed at a first location in a wall of the catheter body  12  and a window into the outflow lumen  20  is skived or otherwise formed at a second location in a wall of the catheter body  12 . Thereafter, as illustrated  FIG. 3 , one end of a tube  14  is passed in alternate transverse directions (e.g., back and forth) through adjacent ones of the bores  13  so that generally U shaped loops of the tube  14  protrude outwardly from opposite sides of the catheter body. A first end (in this example the distal end) of the tube  14  is then inserted through window  22  into inflow  17  lumen and secured to the wall of the inflow lumen  17 . This forms a sealed connection through which inflowing thermal exchange medium will flow from the inflow lumen  17  into the first (e.g., distal) end of the tube. Sealing attachment of the tube  14  to the luminal wall of the inflow lumen  17  may be accomplished by any suitable means such as heat sealing or by adhesive bonding. Examples of adhesives that are useable for this purpose include but are not necessarily limited to cyanoacrylate adhesives (e.g. Loctite 4011 available from the Henkel Corporate, Westlake, Ohio, UV curing acrylic adhesives (e.g., e.g. Loctite 3311 available from Henkel Corporate, Westlake, Ohio, and epoxy adhesives (e.g. Loctite 3981 available from Henkel Corporate, Westlake, Ohio). A second end of the tube  14  (in this example the proximal end) is inserted through window  20  into oufflow lumen  15  and secured to the wall of the outflow lumen  15  in the same manner as described above. This forms a sealed connection through which thermal exchange medium will flow out of the tube  14  and into the outflow lumen  15 . By this arrangement, thermal exchange fluid will enter the distal end of the tube  14  and will exit the proximal end of the tune  14 . However, in some embodiments, it may be desirable to reverse the connections such that the proximal end of the tube  14  will ne connected to the inflow lumen  17  and the distal end of the tube  14  will be connected to the outflow lumen  15 . In such alternative embodiments, the trajectory of the bores  13  may obliterate the distal (unused) portion of the inflow lumen  17  while leaving that portion of the outflow lumen  15  in tact. 
     In some embodiments, it will be desirable to form the protruding U shaped loops of tubing into desired shapes by thermosetting or other suitable forming techniques. As shown in  FIGS. 4 and 4A , in this example, the protruding U shaped loops of tubing  14  are formed so as to circumferentially curve around one side of the catheter body  12 , as shown. Also, as shown in  FIGS. 4 and 4A , when fully assembled, the catheter device of this invention includes a hub  30  on its proximal end, with an outflow lumen connector  32  (connected to outflow lumen  17 ), inflow lumen connector  34  (connected to inflow lumen  15 ), medial infusion lumen connector  36  (connected to medial infusion lumen  18 ), distal infusion of guidewire lumen connector  36  (connected to the distal infusion/guidewire lumen  16 ) and proximal infusion lumen connector  36  (connected to proximal infusion lumen  19 ) extending therefrom. Optional graduated distance markings  42  are formed on a proximal region of the catheter body  12  to indicate the length of catheter that is indwelling in the body at any particular time. Also, an optional proximal radiographic marker  48  and an optional distal radiographic marker  50  are located on the catheter body to facilitate radiographic determination of the location of the heat exchanging region (e.g., the protruding tube loops  14 ) within a subject&#39;s body. 
     It is to be appreciated that the invention has been described hereabove with reference to certain examples or embodiments of the invention but that various additions, deletions, alterations and modifications may be made to those examples and embodiments without departing from the intended spirit and scope of the invention. For example, any element or attribute of one embodiment or example may be incorporated into or used with another embodiment or example, unless otherwise specified of if to do so would render the embodiment or example unsuitable for its intended use. Also, where the steps of a method or process have been described or listed in a particular order, the order of such steps may be changed unless otherwise specified or unless doing so would render the method or process unworkable for its intended purpose. All reasonable additions, deletions, modifications and alterations are to be considered equivalents of the described examples and embodiments and are to be included within the scope of the following claims.