Abstract:
A medical device including an inflation element, such as a syringe, and a balloon catheter in which the inflation element includes a series of indicia to which an operative portion of the inflation device can be aligned. The indicia directly correspond to a particular balloon diameter. A method of inflating a balloon to at least two desired diameters in a body lumen and determining the inflation diameter of the balloon within the body lumen. A method of calibrating the inflation device to allow a user to inflate a balloon to a desired diameter.

Description:
RELATED APPLICATIONS 
     This claims the benefit of U.S. Provisional Application Ser. No. 60/375,245, filed Apr. 23, 2002, entitled “Precalibrated Inflation Device For Balloon Catheter.” 
    
    
     TECHNICAL FIELD 
     This invention relates to medical devices, more particularly to inflation devices used in combination with a balloon catheter. 
     BACKGROUND OF THE INVENTION 
     Balloon catheters are commonly used in endoscopic procedures in the biliary tree, such as to extract stones and calculi obstructing the bile duct or pancreatic duct. In such a procedure, the endoscopist typically performs a sphincterotomy at the opening to the common bile duct then replaces the sphincterotome with a balloon catheter and advances it over the indwelling wire guide past the stone. Contrast media is usually injected prior to introduction of the balloon catheter so that the obstruction can be located fluoroscopically and also, to help determine what size of extraction balloon would be most appropriate. The balloon, which is made of latex or some other compliant material, is then fully inflated in the duct to assess the optimum balloon diameter for sweeping the stone from the duct. Generally there is a predetermined amount of infuscate delivered to achieve the nominal volume and diameter of the balloon. Often the endoscopist will elect to deflate the balloon slightly in order to perform the procedure, especially if the nominal or fully inflated diameter of the balloon is too large for the duct. Another reason is that a fully inflated balloon is more taut and thus, more subject to rupture when contacting a sharp edge of a stone within the duct. A partially deflated balloon is more forgiving and less likely to puncture. One problem with partially deflating the balloon to sweep the stone is that the operator cannot readily determine the diameter of the balloon following deflation and thus, must make an educated guess as to whether it is appropriate for that particular patient&#39;s anatomy. The problem is that the calibrations on an inflation device typically refer only to the actual volume being delivered and thus, require that the operator be able to calculate the syringe volume that corresponds to a given balloon size. If a mark is provided that corresponds to the nominal size of that particular balloon, it is of limited use if trying to extrapolate to inflate or deflate to another size. Since the balloon diameter cannot be easily adjusted downward to a known value using a conventional inflation device, a smaller balloon must be used and inflated to the nominal size to achieve certainty of size. This means that the fully inflated smaller balloon may be less forgiving in case of contact with a sharp edge. Because compliant balloons can assume a range of diameters to address a specific need, what is needed is a system that allows the operator to be able to use a single balloon and be able to determine and control the diameter as needed. 
     SUMMARY OF THE INVENTION 
     The foregoing problems are solved and a technical advance is achieved in an illustrative inflation device and a balloon catheter apparatus in which the inflation device includes a series of indicia to which an operative portion of the inflation device (e.g., a plunger head) can be aligned. Each indicia marking corresponds to a particular volume of air or liquid that produces a balloon diameter indicated at the mark when the inflation device is deployed. In an exemplary embodiment, the balloon catheter comprises a biliary stone extraction balloon in which the balloon portion comprises latex or another compliant elastomeric material. In a first embodiment used for the extraction of stones within the biliary or pancreatic ducts, the inflation device comprises a standard 5 ml plastic syringe with a luer fitting that is connectable to a port communicating with the inflation lumen of the balloon catheter. The inflation device includes a stop to hold the plunger at a first position and three indicator markings that correspond to the position to where the plunger head of the syringe should be advanced to result in the balloon being filled to a diameter of 8.5, 12, and 15 mm, respectively. The numerical value of the resultant balloon diameter is indicated next to the mark. In the exemplary embodiment, the leading edge of the first seal of the plunger head is advanced to the mark to achieve the corresponding balloon size. This allows the operator to readily adjust the balloon diameter by inflating or deflating the balloon accordingly without having to calculate or calibrate the volume of air necessary to produce the desired results. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: 
         FIG. 1A  depicts a size view of the illustrative embodiment of the present invention; 
         FIG. 1  a depicts a cross-sectional view taken along Line  1 A- 1 A of  FIG. 1 ; 
         FIG. 2  depicts a partially sectioned side view of the inflation device of the embodiment of  FIG. 1 ; and 
         FIG. 3  depicts an enlarged side view of the balloon portion of the embodiment of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1-3  depict the illustrative balloon apparatus  10  of the present invention which comprises a balloon catheter  12  that includes a shaft portion  44  and balloon portion  13  affixed thereto just proximal to the distal tip  33  of the shaft. The balloon portion  13  is made of a compliant material such as latex, silicone, or another suitable elastomeric material that can allow the balloon to assume a range of diameters, unlike a non-compliant balloon which is inflatable to a single, maximum diameter. The present balloon apparatus  10  further comprises an inflation device  11 , such as the illustrative syringe, which includes a plurality of unique indicia  21  that indicate the predetermined position where the operative portion  20  (e.g., the illustrative plunger) of the inflation device  11  must be advanced or withdrawn to deliver the proper amount of fluid  31 , such as air, to achieve the desired balloon diameter  37 ,  38 ,  39 , respectively (see  FIG. 3 ). The corresponding diameter is indicated in some manner at that particular mark  22 ,  23 ,  24  located on the surface  34  of the syringe barrel  19 , typically by the appropriate corresponding numerical value  28 . Because the internal volume of each model of balloon catheter can vary, the syringe  11  must be pre-calibrated for that particular balloon catheter  12  design so that the indicia  21  accurately indicate the positions to which the inflation device  11  should be advanced. Alternatively, the inflation device  11  may comprise any appropriate manually operated or electromechanical device that is intended for delivering a measurable amount of gas or liquid for inflating a balloon in a medical application. For example, it is contemplated that the series of unique indicia  21  comprise separate buttons or switches that activate the operative portion  20  of the inflation device  11  to deliver a different pre-measured amount of infuscate  31  to the balloon  13 . 
     As depicted in  FIGS. 1 and 1A , the illustrative balloon apparatus  10 , which is used for sweeping gall stones, calculi, or other obstructions from the biliary tree, comprises a triple-lumen balloon catheter  12 , such as a Howell DASH™ Extraction Balloon (Wilson-Cook Medical, Inc.), having a first pair of small lumens  41  dedicated for inflation of the balloon, and a third, larger lumen  42  for both accommodating a standard wire guide  18  and providing a pathway for infusion of contrast media or other agents around the wire guide  18 . Each lumen extends through the shaft portion of the catheter proximally from the distal end  33  or balloon portion  13 , where they communicate with a port  15 ,  17 ,  36  located on the proximal hub assembly  14  of the device. The first pair of lumens  41  provide communication between the a balloon inflation port  44 , (a scive in the catheter tubing located within the balloon  13 ) and the proximal inflation port  15 , which is a luer fitting located at the proximal end of an optional stopcock  16  used to help prevent loss of air pressure once the balloon has been inflated. The distal end  32  of the inflation syringe  11  is configured to couple with the luer fitting (inflation port  15 ). The third lumen  42 , which is generally larger because of its dual function, communicates with both the infusion port  36 , which is configured to receive a second syringe  35  for injection of contrast media or other agents (such as saline for flushing) and a wire guide port  17 , such as a Tuohy-Borst fitting. The two ports  17 ,  36  merge to form a common pathway that comprises the second lumen  42 . The inflation device  11  of the present invention includes a plurality of unique indicia  21  comprising a first, second and third indicium or marking  22 ,  23 ,  24  disposed along the length thereof which includes the corresponding numerical value  28  alongside. The indicia are printed in ink on the outer surface  34  of the syringe barrel, although they can be etched, embossed, or otherwise applied thereto or incorporated thereinto. Alternatively, other types of unique indicia (i.e., other alphanumeric characters, symbols, colors, etc.) may be utilized to correspond with any calibrated balloon diameters  37 ,  38 ,  39  that one wants to identify. 
     Referring now to  FIGS. 2 and 3 , the illustrative inflation syringe  11  includes a stop  30  which comprises a pair of protuberances on the inside of the syringe barrel  19  that temporarily lock the plunger  20  at the designated pre-deployment  43  position. The rear edge  29  or flange of the plunger head  25  is configured to rest against the stop  30  until additional force is applied during deployment to overcome resistance provided by the stop  30 . The plunger  20  is then advanced to the marking  21  corresponding to the desired balloon size. The first marking  22  corresponds to the position to which the plunger  20  of the inflation syringe  11  is advanced to achieve a first balloon diameter  37  of 8.5 mm. To inflate the balloon to the first diameter, the plunger head  25 , which includes a distal and a proximal seal  26 ,  27 , is positioned such that the leading edge of the distal seal  26  is aligned at the mark  22 . Typically, the plunger head must be advanced beyond the first mark  22  (e.g., to the second mark  23 ) and subsequently withdrawn back to the first mark  22  when inflating the balloon  13  to the smaller diameters, such as 8.5 mm. This is generally not necessary for the larger balloon diameters. The plunger head is aligned with the second mark  23  to inflate (or deflate) the balloon to the second diameter  38  (12 mm) or aligned with the third mark  24  (essentially the full deployment of the syringe contents  31 ) to inflate the balloon  13  to the third diameter  39 , which is about 15 mm. While these diameters represent the most commonly available biliary extraction balloon sizes, any precalibrated balloon diameters may be indicated depending on the application or the physician preference. In addition, the present invention may be adapted for vascular, pulmonary, genitourinary, or other gastrointestinal uses which might require a different range and set of balloon diameters. 
     Any other undisclosed or incidental details of the construction or composition of the various elements of the disclosed embodiment of the present invention are not believed to be critical to the achievement of the advantages of the present invention, so long as the elements possess the attributes needed for them to perform as disclosed. The selection of these and other details of construction are believed to be well within the ability of one of even rudimentary skills in this area, in view of the present disclosure. Illustrative embodiments of the present invention have been described in considerable detail for the purpose of disclosing a practical, operative structure whereby the invention may be practiced advantageously. The designs described herein are intended to be exemplary only. The novel characteristics of the invention may be incorporated in other structural forms without departing from the spirit and scope of the invention. Unless otherwise indicated, all ordinary words and terms used herein shall take their customary meaning as defined in  The New Shorter Oxford English Dictionary,  1993  edition . All technical terms shall take on their customary meaning as established by the appropriate technical discipline utilized by those normally skilled in that particular art area. All medical terms shall take their meaning as defined by  Stedman &#39;s Medical Dictionary,  27 th edition.