Patent Publication Number: US-9884171-B2

Title: Catheter system providing step reduction for postconditioning

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 13/032,733 filed Feb. 23, 2011, which is a Continuation-In-Part of U.S. patent application Ser. No. 12/771,968 filed Apr. 30, 2010, and is a Continuation-In-Part of U.S. patent application Ser. No. 12/771,946, filed Apr. 30, 2010, the entirety of which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a catheter having a fluid circuit to control and modulate flow of inflation fluid to and from a balloon disposed at a distal section of the catheter system for reducing the number of steps and time required to perform postconditioning. 
     BACKGROUND OF THE INVENTION 
     When a patient suffers from an ischemic event, the blood supply to tissues and organs distal to the blockage or occlusion is significantly diminished. The resulting deprivation of oxygen increases the risk of necrosis of the tissues and organs. Generally, a patient suffering an ischemic event is treated by minimally invasive catheterization, such as for example percutaneous transluminal coronary angioplasty (PCTA). PCTA is employed to dilate the ischemic blockage and to restore the blood supply to the tissues and organs. Rapid restoration of blood flow after an ischemic event minimizes the duration of insufficient oxygenation to the tissue and organs, and therefore optimizes tissue and organ survival. However, it has now been found that restoring blood supply in a rapid and consistent manner results in reperfusion injury. A shock to the tissues and organs from rapid oxygen re-saturation and abrupt changes to pH level in the tissue can results in an overall increase in the infarct size. 
     Reperfusion injury results from the rapid opening of a blood vessel such as those of the coronary, peripheral, and/or cerebral vasculature. For example, the rapid opening of an artery of the heart during a ST-Elevation Myocardial Infarction (“STEMI”), or an artery to the brain (ischemic stroke), or an artery to the other vital organs such as the kidney or liver or other tissues of the body sometimes causes ischemic injury in myocardial, cerebral, peripheral and spinal infarction, for example. 
     One method to reduce or prevent the occurrence of reperfusion injury is a technique known as postconditioning. Postconditioning is a method during which the blood flow in the infarcted artery is stopped and started for multiple cycles immediately after re-opening of initial flow from the STEMI. This re-opening of flow can be either before or after angioplasty, with or without placement of a stent. Currently, physicians typically use an angioplasty catheter to perform postconditioning. However, the use of an angioplasty catheter is not optimal. For example, the angioplasty balloon is not configured to quickly occlude flow. Instead, the angioplasty balloon is designed to carefully create a new, circular lumen. Additionally, the typical angioplasty balloon is non-compliant, meaning it is designed and/or made of a material that is meant to be inflated with a range of pressures, while not significantly changing its outer diameter size. A typical non-compliant angioplasty balloon becomes circular at approximately 4 atmospheres of pressure. As the balloon pressure is increased, the outer diameter grows very little even as pressure is increased to 14-18 atmospheres. Such characteristics can be drawbacks for postconditioning. Further, an angioplasty balloon is typically designed to open a stenosis or blood vessel along a lesion, rather than just occlude flow. Thus, the length of an angioplasty balloon is generally between 8 mm to 40 mm, while an occlusion balloon could be shorter. 
     Another major drawback to using an angioplasty catheter for postconditioning is that prior to use, the physician must measure the artery, for example, by fluoroscopy, then size the balloon both for length and diameter, retrieve an appropriately sized balloon from inventory, and then go through various steps to prepare the balloon such as removing the air trapped within the balloon before filling the balloon with saline/contrast mixture. Thus, using the angioplasty catheter with the angioplasty balloon suffers from inefficiencies. Further, the angioplasty catheter typically must be manually actuated to both inflate and deflate the balloon. For example, the use of an angioplasty catheter for postconditioning usually requires rapid rotation of a screw piston in order to deliver the fluid in a controlled manner, while watching the pressure gage of an Indeflator. Inflation of the balloon to a circular size can require 10-20 twists of the Indeflator in order to expand the balloon. During deflation, the Indeflator is normally directly unlocked and rapidly deflated. If a controlled deflation is required, then the Indeflator can be manually screwed down to a lower pressure. Physician to physician variability will directly ensue, meaning that over the course of multiple inflations and deflations, there will be a great variability in the rise and fall of blood flow in the artery. Normalizing the blood flow, i.e. the rate of inflation, pressure of inflation, and rate of deflation across physicians can be critical to the efficacy of postconditioning. In addition to the cumbersome nature of actuating inflation and deflation of the angioplasty catheter, the speed of inflation is limited by the physical capability or limitations of the treating physician to rapidly rotate the screw piston. Given that many sequential inflations and deflations are needed during a postconditioning, use of an angioplasty catheter has many drawbacks. As a result much time is lost in the process of using a conventional angioplasty catheter for postconditioning. 
     Use of a conventional angioplasty catheter can also result in significant operator-to-operator variability in inflation time, pressure of balloon, size of balloon, and deflation time. A system which normalizes the inflation time, pressure, size and deflation time is required, while still allowing operator control of the duration of inflation. Lastly, angioplasty balloons, especially rapid exchange balloons, do not have any means to deliver drug distal to the balloon without the added steps of removing the rapid exchange guidewire and replacing the rapid exchange guidewire with an over-the-wire guidewire. 
     Therefore, a need exists for a system that is capable of restoring blood flow after an ischemic event in an intermittent and gradual fashion with ease and efficiency, while allowing the option of drug delivery distal to the balloon over a standard length guidewire. Further, there remains a need for a pre-assembled kit for administering ischemic postconditioning comprising a catheter and a handle having a fluid circuit to control and modulate flow of inflation fluid to and from a balloon wherein the catheter is free from additional assembly and preparation procedures such that it is ready-to-use within a variety of vessel sizes. A need also exists for a fool-proof balloon catheter for angioplasty techniques, as described below. The disclosed subject matter includes a method and apparatus for performing ischemic postconditioning in a much shorter time and at significantly reduced risk to the patient than is possible with prior art technology. 
     Additionally, as mentioned above, PCTA is employed to dilate the ischemic blockage and to restore the blood supply to the tissues and organs when a patient suffers from an obstructed blood vessel, typically as a result of atherosclerosis. During PCTA, an empty (deflated) and collapsed balloon disposed on a catheter is usually passed into the narrowed location of the blood vessel and then inflated to a fixed size. Inflation of the balloon at the narrowed location of the blood vessel compresses the obstruction to open up the blood vessel for improved flow. During the angioplasty procedure, the physician is required to determine whether the balloon is inflated by reviewing the balloon on a monitor or screen usually away from the patient undergoing the treatment. Thus, the physician must be careful enough to maintain the catheter at the lesion and take his view away from the patient to view the screen to make the determination if the balloon is inflated or depend on another to view the monitor. Thus, there is a need for an easy to use balloon catheter having an indicator to indicate to the physician when the balloon is inflated in a manner assures the physician the balloon is inflated without being required to turn away from the patient or make the judgment from a monitor. 
     SUMMARY OF INVENTION 
     The purpose and advantages of the present invention will be set forth in and apparent from the description that follows, as well as will be learned by practice of the present invention. Additional advantages of the present invention will be realized and attained by the methods and systems particularly pointed out in the written description and claims hereof, as well as from the appended drawings. 
     To achieve these and other advantages and in accordance with the purpose of the disclosed subject matter, as embodied and broadly described, the disclosed subject matter includes a method of administering ischemic postconditioning comprising providing a catheter, the catheter including an expandable member, the catheter configured for use in a variety of vessel sizes, the catheter configured to receive a guidewire of predetermined size. A pressure source is provided and coupled with the catheter, with the expandable member disposed in fluid communication with the pressure source, wherein the catheter is free from additional assembly and preparation procedures. The expandable member is positioned at a predetermined location within a vessel and inflated with an inflation fluid for a period of time, and thereafter deflated. 
     Additionally, a therapeutic agent can be delivered simultaneously with postconditioning. Further, the catheter can be configured to receive a rapid exchange guidewire during delivery of the therapeutic agent. The expandable member conforms to the vessel wall having a non-circular cross-section at a pressure of about ⅔ atmospheres, and is repeatedly inflated for about 30 seconds with an inflation liquid, e.g., CO 2 . 
     In accordance with another aspect of the invention, the catheter is configured as a single-piece device arranged in a pre-assembled kit wherein the catheter and handle, which includes a fluid circuit in communication with the expandable member, comprise a system ready-to-use within a variety of vessel sizes. 
     In accordance with another aspect of the invention, a catheter that is capable of efficient inflation and deflation of an expandable member is provided. The catheter includes a fluid circuit generally having first and second tubes and a plurality of valves to modulate flow of inflation fluid to a balloon disposed on the catheter body. In some embodiments, the catheter further includes an indicator that is configured to indicate to the physician whether the balloon is inflated while the balloon is in vivo. The advantages of the catheter removes the necessity of the physician to turn to view the balloon from fluoroscopic screen to determine whether the balloon is indeed inflated. 
     In one embodiment, the catheter is part of a system for reducing or preventing reperfusion injury to a patient. In this regard, the balloon is preferably a compliant balloon having a length and compliance for sequential inflation and deflation to effectuate postconditioning techniques, such as those described in U.S. Publication 2004/0255956 to Vinten-Johansen et al., the contents of which are incorporated herein by reference thereto. However, the catheter is applicable for use with other applications, such as angioplasty, stent delivery, etc. In this regard, the balloon need not be a compliant balloon or a balloon capable of sequential inflation and deflation. Instead, a typical angioplasty balloon can be employed, as would be known in the art. 
     In one embodiment, the catheter includes an elongate shaft having a proximal end, a distal end and a length therebetween. The elongate shaft includes an inflation lumen and a guidewire lumen. An expandable member is disposed at or near the distal end of the elongate shaft. The catheter further includes a fluid circuit. The fluid circuit modulates inflation fluid flow to inflate and deflate the expandable member. 
     In some embodiments, at least a part of the fluid circuit is housed in a handle at the proximal end of the elongate shaft. The catheter system can include a non-removable handle attached to the elongate shaft. In this regard, the catheter system can be a disposable unit with no assembly required prior to use. The handle can include an actuator to effect inflation or deflation of the expandable member. In this manner, the actuator controls fluid flow through the fluid circuit of the catheter. The actuator can have a first position to actuate inflation fluid flow to the expandable member, and/or a second position to actuate deflation fluid flow from the expandable member. The first position can include a momentary direction. The second position can include a detentable direction. In some embodiments, the system contains no more than one actuator to inflate and deflate the expandable member. The actuator can be, for example, a switch, a button, or a lever. The switch, button, or lever or other actuator can be configured to prevent overinflation of the expandable member. In this manner, the actuator provides the user with a one-touch actuation capability, and further, the prevention of overinflation provides a “fool-proof” system. 
     In some embodiments, the system includes a safety member to prevent inflation fluid flow. The safety member can be housed in the handle of the system. In this manner, the safety member prevents commencement of inflation fluid flow through the circuit. 
     The fluid circuit provides, in some instances, a closed loop circuit. The fluid circuit for example can include a first reservoir to house the inflation fluid, and inflation fluid passageway, such as the inflation lumen, and a plurality of valves to control flow of the inflation fluid to a balloon. The fluid circuit includes a piercing member, such as a lancing device to pierce or tap the first reservoir to release the inflation fluid. In some embodiments, the piercing member controllably taps the first reservoir. In some embodiments, the system includes a regulator to control pressure from the inflation fluid once released from the reservoir to the actuator. In some embodiment, the regulator is a valve. 
     In some embodiments, the actuator controls inflation fluid flow from the handle to an inflation lumen. The actuator can control inflation flow through the inflation lumen to the expandable member. A splitter can be employed to send or modulate the inflation fluid to the inflation lumen of the catheter. A second splitter having pulse valve can be used to effectuate a time controlled flow of inflation fluid to the inflation lumen. In some embodiments, the fluid circuit further includes a check valve to direct flow of inflation fluid from the pulse valve to the inflation lumen. In some embodiments, a connector valve connects a deflation tube having a lumen from the expandable member to the check valve. An indicator can be disposed at the deflation tube to provide information about inflation or deflation of the expandable member. In some embodiments, the indicator is an air indicator. Thus, the air indicator senses air pressure from the inflation fluid in the deflation tube signaling that the inflation fluid reached the expandable member and inflated the expandable member such that the inflation fluid continued in the circuit to the deflation fluid. The expandable member is preferably a balloon. In some embodiments, such as those for treating reperfusion injury the balloon is sequentially inflatable and deflatable. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the disclosed subject matter claimed. 
     The accompanying drawings, which are incorporated in and constitute part of this specification, are included to illustrate and provide a further understanding of the method and system of the disclosed subject matter. Together with the description, the drawings serve to explain the principles of the disclosed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A detailed description of various aspects, features, and embodiments of the subject matter described herein is provided with reference to the accompanying drawings, which are briefly described below. The drawings are illustrative and are not necessarily drawn to scale, with some components and features being exaggerated for clarity. The drawings illustrate various aspects and features of the present subject matter and may illustrate one or more embodiment(s) or example(s) of the present subject matter in whole or in part. 
         FIGS. 1A-1B  are schematic illustrations of a postconditioning method in accordance with one embodiment of the disclosed subject matter; 
         FIGS. 2A-2C  are schematic views of the system in accordance with one embodiment of the disclosed subject matter; 
         FIG. 3A-3E  are schematic illustrations of the catheter shaft in accordance with embodiments of the disclosed subject matter; 
         FIGS. 4A and 4B  are perspective views of embodiments of balloons in accordance with the disclosed subject matter; 
         FIGS. 5A and 5B  are cross sectional views of some embodiments of the handle in accordance of with the disclosed subject matter; 
         FIGS. 5C to 5R  are perspective views of various embodiments of handles in accordance with the disclosed subject matter; 
         FIGS. 6A to 6C  are schematic illustrates of a pulse valve in accordance with the disclosed subject matter; 
         FIG. 7A  is an exploded view of fluid circuit in accordance with one embodiment of the disclosed subject matter; 
         FIGS. 7B-7U  are perspective views of exemplary components of the fluid circuit of  FIG. 8 ; and 
         FIGS. 8A to 8C  are block diagrams illustrating the inflation fluid flow through the fluid circuit in accordance with one embodiment of the disclosed subject matter. 
         FIGS. 9A to 9N  are side views of some embodiments of an arming device in accordance with the disclosed subject matter. 
         FIG. 10  is a graphical presentation of a comparison of physician attention allocation, in accordance with the disclosed subject matter. 
         FIG. 11  is a graphical presentation of a comparison of inflation and deflation times, in accordance with the disclosed subject matter. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     It is understood that the subject matter described herein is not limited to particular embodiments described, as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present subject matter is limited only by the appended claims. Where a range of values is provided, it is understood that each intervening value between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the disclosed subject matter. 
     I. System Overview 
     In accordance with the invention, a system is configured to permit sequential, such as intermittent and repeated, inflation and deflation of an expandable member, such as a balloon. In some embodiments, the sequential inflation and deflation of the balloon is achieved by single-touch actuation. The term “single-touch” as used herein means that actuation of inflation and deflation of the expandable member can be achieved by a single switch, single button, or other single point of actuation. In this regard, the user simply presses or otherwise actuates an actuator to inflate the balloon, and presses it again to actuate deflation of the balloon. Thus, unlike the angioplasty catheter that generally requires sizing, prepping, and inflating by rotation of a screw on the indeflator, one embodiment of the present system avails itself of quick use without the need for preparation. 
     A step by step comparison shows that while an angioplasty balloon catheter requires many steps to size, prep, remove air bubbles and use the device, a catheter system in accordance with an embodiment of the present system is much more efficient, thereby providing a shorter procedure time and reduced risk to the patient. 
     
       
         
           
               
               
               
             
               
                   
               
               
                 Steps 
                 Typical Angioplasty System 
                 One Embodiment of the System 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 1. 
                 Size vessel proximal to lesion 
                 Get package containing system 
               
               
                 2. 
                 Determine size of balloon 
                 Open Box containing system 
               
               
                   
                 needed 
               
               
                 3. 
                 Get Box(s) 
                 Unwrap Product 
               
               
                 4. 
                 Look Up Compliance Chart 
                 Engage Pressure 
               
               
                 5. 
                 Choose final size 
                 Advance to target lesion over 
               
               
                   
                   
                 guidewire 
               
               
                 6. 
                 Open box containing 
                 Flip switch On (no purge 
               
               
                   
                 angioplasty system 
                 required, no air bubbles if carbon 
               
               
                   
                   
                 dioxide fluid used) 
               
               
                 7. 
                 Unwrap product 
                 Flip switch off 
               
               
                 8. 
                 Purge Indeflator 
                 Repeat steps 6 and 7 to 
               
               
                   
                   
                 sequentially inflate and deflate 
               
               
                 9. 
                 Connect Balloon to Indeflator 
               
               
                 10. 
                 Prep Balloon (1st time = 3 
               
               
                   
                 steps) 
               
               
                 11. 
                 Prep Balloon (2nd time = 3 
               
               
                   
                 steps) 
               
               
                 12. 
                 Confirm no air bubbles 
               
               
                 13. 
                 Advance to target lesion 
               
               
                 14. 
                 Lock Indeflator 
               
               
                 15. 
                 Twist handle while watching 
               
               
                   
                 dial until target pressure 
               
               
                   
                 diameter curve is reached 
               
               
                   
                 (about 8 atm) 
               
               
                 16. 
                 After 30 seconds, unlock 
               
               
                   
                 Indeflator 
               
               
                 17. 
                 Pull vacuum 
               
               
                 18. 
                 Repeat steps 14-17, repeat 
               
               
                   
                 prep balloon if bubbles seen 
               
               
                   
               
            
           
         
       
     
     This reduction in the number of steps and procedure time between conventional angioplasty balloons and the present invention is heightened when a therapeutic agent is delivered through the catheter. That is, angioplasty balloons, especially rapid exchange balloons, do not have any means to deliver drug distal to the balloon without the added steps of removing the rapid exchange guidewire and replacing the rapid exchange guidewire with an over-the-wire guidewire. Accordingly, the present invention alleviates this requirement and instead can deliver a therapeutic agent through the catheter while the catheter is coupled with a rapid exchange guidewire. 
     The size and diameter of the balloon to be used in a conventional angioplasty procedures is required to be matched to the size and native diameter of the obstructed segment of the artery to be dilated. If the balloon size and diameter is smaller than the native artery, the results of balloon angioplasty are suboptimal, requiring a second dilation with a larger-sized balloon. In some cases, the result is a failed procedure, which may require either a second separate angioplasty procedure or bypass surgery. If the balloon is oversized in relation to the obstructed segment of the native vessel, the inner wall of the artery may dissect from the remainder of the artery and may occlude the vessel completely, causing total cessation of blood flow to the target area of the myocardium. This complication can lead to acute myocardial infarction and necessitate emergency bypass surgery. If the acute occlusion leads to a large infarction, death is a possibility. 
     If a patient has a single obstruction in the right or left coronary artery system, a single balloon catheter with a matching diameter and size will be selected for the intended dilation procedure. When the balloon is inflated inside the obstructed segment of the native artery, the balloon should maintain the original preshaped configuration and diameter under the maximum allowed pressure. In single lesion dilations, the choice of a properly-sized balloon catheter is relatively simple, although there are instances in which the original selection of the balloon catheter is inadequate so that a second balloon Catheter is necessary to complete the procedure successfully. 
     However, in multi-vessel disease, balloon catheter selection becomes compounded and complex. For example, a patient may have three lesions in the left coronary artery, and all three lesions may be approachable individually for successful balloon angioplasty. But such lesions may be in vessels of different sizes. With conventional balloon catheters, angioplasty of these three differently-sized lesions is not always impossible, but it is cumbersome and inefficient. For each lesion, a matching balloon catheter is exchanged and manipulated into the target lesion. To do this three times in a row requires roughly three times the procedure time, three times the contrast amount, and a minimum of three separate balloon catheters and their accessory devices. Accordingly, the present invention provides a more efficient and effective balloon catheter system designed as a pre-assembled device capable of delivery within a variety of vessel sizes, so as to provide a one-size-fits-all device for which the operator need not select a pressure or volume for inflation of the balloon. 
     In this regard, one embodiment of the system provides physicians with an efficient, easy to use catheter designed for rapid, sequential or repeated inflation and deflation of a balloon, such as for reducing or preventing reperfusion injury to an organ or tissue after an ischemic event in the context of preventing or reducing reperfusion injury, or for other applications. For applications in which the system is employed for postconditioning applications, the system can be employed to (1) stop perfusion to the organ or tissue for an amount of time, and (2) permit perfusion to the organ or tissue for another period of time, repeating the stopping and perfusion steps sequentially, and (3) deliver beneficial agents or contrast to areas distal to the balloon. 
     Beneficial agents include drugs, proteins, therapeutic agents, and other agents that promote health or recovery. Some non-limiting examples include calpain inhibitors, endothelin receptor blockers, pH stabilizing agents, antithrombotic agents, and proteins, cells or vectors including angiogenic factors. Certain non-limiting calpain inhibitors and other beneficial agents are disclosed in WO 98/25899, WO 98/25883, WO 9954305, WO 99/54310, WO 99/61423, WO 00/78933, WO 2008/080969, WO 2009/083581, U.S. Publication Nos. 2006/0205671 and 2008/0097385, each of the disclosures of which are incorporated herein by reference. Other examples of beneficial agents include nitroglycerin, epinepharin, lydocaine, heparin, hirudin, and ReoPro™. As will be recognized in the art, however, other drugs or beneficial agents may be employed. 
     In one embodiment, the catheter system as described herein is useful for postconditioning methods. In this manner, the expandable member, preferably a balloon, is configured to occlude a blood vessel during expansion or inflation of the expandable member, and then permit resumption of perfusion of the blood flow during contraction or deflation of an expandable member. The occluded vasculature can include a venous blood vessel as in retroperfusion, or an arterial blood vessel such as in reperfusion. The occluded blood vessels may be from the coronary, peripheral, or cerebral vasculature. As illustrated in the schematic of  FIG. 1A , in one embodiment postconditioning is achieved by inflating and deflating the catheter balloon proximal to a lesion for one or more cycles of about 10 to 60 seconds. These cycles are repeated as necessary to perform the postconditioning therapy. For example, an expandable member is sequentially contracted and expanded such as to permit perfusion for about 10 to about 60 seconds and stop perfusion for about 10 to about 60 seconds for a one or more cycles. In some embodiments, the cycles are repeated for about 3 to about 10 cycles. As shown in  FIG. 1A , in one embodiment, the cycles for both inflation and deflation are for a period of about 30 seconds each. Other postconditioning methods can be employed, however, such as postconditioning methods described in U.S. Patent Publication No. 2004/0255956 and 2007/0160645 to Vinten-Johansen et al., the disclosures of which is incorporated herein by reference for all purposes. In some embodiments, the catheter is designed to postcondition a stented blood vessel without changing the dimension of the implanted stent. In this manner, the expandable member is a compliant balloon as described below, which does not negatively affect the implanted stent during postconditioning cycles of inflation and deflation of the balloon. 
     As illustrated in  FIG. 1B , the postconditioning technique can be employed prior to stenting a blood vessel or subsequent to stenting a blood vessel. 
     With regards to postconditioning prior to or after stenting, the postconditioning device embodied herein will not dislodge the plaque. With regards to postconditioning after stenting, the postconditioning can occur proximal to the stent, distal to the stent, and/or inside the stent. Advantageously, the catheter device embodied herein does not alter the shape or dimension of the deployed stent when postconditioning is employed within the stented vessel. 
     Accordingly, embodiments of the catheter of the invention can be used for postconditioning before or after placement of a stent in a blood vessel. 
     As shown in  FIG. 2A , the catheter system  10  generally includes a catheter having an elongate shaft  200 , an expandable member  300  and a fluid circuit including a control system  1000  ( FIG. 2B ) housed in a handle (not shown). In some embodiments, handle  100  ( FIG. 5A ) is non-removably attached to the catheter system such that a single unitary device is provided. Advantageously, the unitary device is packaged in a ready-to-use state. In other words, the device can be a pre-assembled unit that is ready for use in any size vessel thereby eliminating the need for measuring of the patient and selection of the appropriate size balloon and catheter, as is required in prior art devices. An exemplary embodiment of the pre-assembled unit is illustrated in  FIG. 2C . Once the device is removed from any packaging provided and coupled with the inflation fluid source, described in further detail below, the device is ready for use. Further, in applications in which a therapeutic agent is delivered, the device of the present invention provides for a more efficient procedure in that a rapid exchange guidewire can remain disposed within the lumen of the catheter during delivery of the therapeutic agent. In some embodiments, expandable member  300  is disposed at a distal section of the elongate shaft of the catheter. 
     The elongate shaft  200  includes at least two lumen, as better seen in  FIGS. 3A to 3C . In one embodiment, the at least two lumen include an inflation lumen and a separate dedicated independent deflation lumen. Both the inflation lumen and the independent deflation lumen are in fluid communication with the interior portion of a balloon  300 . In this regard, an inflation fluid of any pressurized fluid, such as carbon dioxide, noble gases including helium, neon, and pressurized liquids such as saline or contrast agents, is introduced into the balloon  300  via the inflation lumen to inflate the balloon and then exits the balloon via the independent deflation lumen. The independent deflation lumen allows for rapid deflation of the balloon and in one embodiment is configured for Venturi-assisted deflation, as described below. 
     A handle  100  is disposed at or near the proximal end of the catheter and houses the control system  1000  of the fluid circuit ( FIGS. 5A and 5B ). Handle  100  is configured to provide a physician with the ease of automatic, sequential inflation and deflation of expandable member  300  by, in some embodiments, a one-touch actuator. In this manner, the one-touch actuator can be a switch, button, lever, or other device adapted to permit a user to inflate expandable member  300  when actuated in a first position or direction, and to deflate expandable member  300  when actuated in a second position or direction. The one-touch ease of sequential inflation and deflation of expandable member  300  can be achieved by adapting the catheter shaft to include an independent inflation lumen and separate independent deflation lumen. In some embodiments, the switch is configured such that the user cannot overinflate the expandable member  300 . In this regard, the system can include a pulse valve that closes an outlet port to the expandable member when the expandable member is fully inflated thereby preventing over inflation. In this manner, when the balloon is fully inflated further actuation of the switch does not further inflate the balloon, thereby rendering the system “fool-proof” and effectuating reproducibility with relation to inflation of the expandable member. 
     In some embodiments, the handle  100  includes a control system  1000  of a fluid circuit disposed within the catheter device. The control system  1000  is configured to assist modulation of inflation fluid flow throughout the fluid circuit of the catheter system such as to effectuate inflation and deflation of the expandable member  300 . In some embodiments, the fluid circuit and in particular the independent deflation lumen can be configured to induce a Venturi-assisted flow to rapidly deflate expandable member  300 , as will be described below. 
     II. The Catheter Body 
     In accordance with one embodiment, as shown  FIG. 3A , the catheter includes a generally elongate tubular shaft  200  having a proximal shaft segment  201  and a distal shaft segment  202  in fluid communication. Proximal shaft segment  201  and distal shaft segment  202  can be formed from material having the same or similar hardness or durometer to provide a uniform flexibility along the catheter body. Alternatively, the proximal shaft segment and distal shaft segment can be formed from materials having different flexibilities to provide a catheter having a varied flexibility along a length thereof. For example but not limitation, the proximal shaft segment may be formed from a hypotube and the distal shaft can be formed from a polymeric material to provide increased flexibility along the catheter tubular shaft. As such, the proximal shaft and distal shaft segments can be formed from the same tube or alternatively can be two separate tubes connected or welded together to form a unitary tube. The catheter may comprise one or more polymers or polymer blends having different stiffness. 
     As illustrated in  FIG. 3B , elongate shaft  200 , in one embodiment, includes an independent inflation lumen  203  configured to provide a passage or flow of inflation fluid to an expandable member  300  disposed at or near the distal end  202  of the catheter shaft. Elongate shaft  200  can also include an independent deflation lumen  204  to provide a second fluid flow passage for the inflation fluid to outflow from expandable member  300  during deflation. In this manner, the sequential inflation and deflation of expandable member  300 , and consequential stopping and starting of blood flow during postconditioning techniques can be efficient and rapid. For example, in one embodiment of the system, the expandable member  300  can be inflated in five seconds or less, preferably one second or less, most preferably in 1/15th of a second or less. Further, the expandable member can be deflated in five seconds or less, and preferably three seconds or less, most preferably ¼ of a second or less. This rapid inflation and deflation of the expandable member provides advantages for postconditioning techniques not available through use of the conventional angioplasty catheter. 
     The elongate shaft  200  can be formed in a number of shapes, for example, in one embodiment, the shaft can have a tubular configuration as shown in  FIG. 3B . However, as would be known in the art other shapes can be employed, such as elliptical. 
     The elongate shaft  200  can further include guidewire lumen  205 , for example, in addition to the inflation and deflation lumen. In this regard, guidewire lumen  205  can be configured to extend from a tip  400  at the distal end of elongate shaft  200  to a more proximal location of the elongate shaft  200  to provide an over-the-wire catheter. Alternatively, elongate shaft  200  may be formed to have a notch (not shown) disposed at a location between the distal end  202  and proximal end  201  of elongate shaft  200  to provide a rapid exchange catheter. 
     In accordance with another embodiment, elongate shaft  200  can further include a drug delivery lumen  206 , such as for example, a drug infusion lumen configured to locally deliver beneficial agents such as those described above or other agents. In one embodiment, the beneficial agents are locally delivered to an area of a ischemic event. In other embodiments, the catheter lacks a drug delivery lumen and instead, a drug coated balloon is disposed on the catheter shaft for local delivery of a beneficial agent. 
     In some embodiments, the elongate shaft  200  includes four separate and independent lumen (e.g., inflation lumen  203 , deflation lumen  204 , guidewire lumen  205 , and drug delivery lumen  206 ). However, other configurations can be employed. In some embodiments, the diameters of the lumen have different sizes. For example, in some embodiments, the deflation lumen has a diameter of about twice the size of the inflation lumen diameter. In one embodiment, as depicted in  FIG. 3C , the diameter of the inflation lumen  203   d  is about 0.100 mm, the diameter of the deflation lumen  204   d  is about 0.200 mm, the diameter of the guidewire lumen  205   d  is about 0.400 mm, and the diameter of the infusion lumen  206   d  is about 0.300 mm. Accordingly, each lumen can be configured to have a different sized diameter, if desired. 
     In some embodiments, as illustrated in  FIG. 3B , elongate shaft  200  can be formed from a single extrusion with a plurality of lumen, e.g., the four lumen as described above. As further shown, the four lumen can be oriented within the extrusion so that the extruded polymeric web  208  remaining between the lumen forms an “I-beam” cross section. An I-beam configuration provides efficient form for resisting both bending and shear in the plane of the polymeric web  208 . In this manner, the plurality of lumen  203 ,  204 ,  205 ,  206  are configured as independent lumen physically spaced from one another by polymeric web  208  disposed therebetween. An advantage of the I-beam shape is that the catheter shaft is more resistant to bending when the catheter is pulled in a particular direction. 
     In some embodiments, the different sized lumen are arranged or oriented within the extrusion to form a pattern such that the largest sized lumen  205  is proximate each of the smaller sized lumen  203 ,  204 ,  206 , as depicted in  FIGS. 3B and 3C , such that the polymeric web  208  disposed between the lumen  203 ,  204  and  205  forms the I-beam pattern, as illustrated in  FIGS. 3D and 3E . In some embodiments, the thickness of extruded polymeric web  208  is substantially equivalent to the bending moment of the shaft. A bending moment exists in a structural element when a moment is applied to the element so that the element bends. Moments and torques are generally measured as a force multiplied by a distance so they have as unit newton-meters (N·m), or foot-pounds force (ft-lbf). In this manner, it is believed that the elongate shaft  200  will resist bending equally, regardless of the direction of the bend to the catheter shaft. It is further believed that a catheter shaft without these features will bend to a different degree depending upon the orientation inside the vessel. 
     Elongate shaft  200  can further include a distal tip  400  ( FIG. 3A ) having a proximal end abutting or overlapping the distal end  202  of the catheter body. In one embodiment, catheter tip  400  includes one or more lumen. For example, in one embodiment, the tip  400  can include a first lumen aligned with guidewire lumen  205  of elongate shaft  200 , and a second lumen aligned with infusion lumen  206 . The guidewire lumen  205  is aligned with a lumen through the catheter tip  400  disposed at the distal end of the catheter shaft  202 . These aligned lumens permit the catheter to ride over a guidewire. Furthermore, once properly inserted, the guidewire can be removed and fluid can be passed through the lumen. 
     In one embodiment, the tip  400  can be formed of a material softer than the material of the catheter such that the tip has sufficient column strength to resist buckling during insertion, but is sufficiently flexible to deform when the tip is subjected to axial or radial loads in the body in the absence of the guidewire. Catheter elongate shaft  200  is configured to enable the passage and the longitudinal translation of guidewire within lumen  205  during a surgical procedure. 
     Elongate shaft  200  can be produced from a variety of materials, including metal, plastic and composite materials. In one embodiment, proximal shaft  201  is manufactured as a metal tube, for example, as a stainless steel hypotube, and may be coated with a polymeric material such as PTFE. The metal tube may also be covered with a single or multilayered plastic material through one or more processes, including coextrusion, dipping, heat-shrinking, and electrostatic and thermal coating. In another embodiment, elongate shaft  200  is manufactured as a plastic tube. Materials suitable for use in the catheter tube include, but are not limited to, Polyurethanes (PU), such as Tecoflex, Pellethene, Bionate, corethane, Elasteon, and blends thereof; Polyethylenes (PE), such as PET, PBT, PVDF, Teflon, ETFE, and blends thereof, Polyolefins, such as HDPE, PE, LDPE, LLDPE, Polypropylene, and blends thereof, Polyimides; Polyamides; all classes of Nylons, such as Nylon 11, Nylon 12, Nylon 6,6, Nylon 6, Nylon 7,11, Nylon 11,12, and blends thereof); block copolymers; PEBA-types polymers, such as ELY, PEBAX, Ubesta, and blends thereof, and biodegradable polymers. 
     Suitable materials also include blends of the above mentioned materials as well as any composite materials, like dual-layers, tri-layers and multi-layers thereof. For example, catheter shaft may be produced from a tube comprising an outer layer made of Nylon and an inner layer made of a lubricious material such as polyethylene or PTFE. A metallic or nonmetallic braiding may also be included within or between layers of the catheter shaft. 
     Catheter tip  400  can be configured to provide atraumatic contact between elongate shaft  200  and a wall against which elongate shaft  200  may be pushed during a surgical procedure. The catheter tip can be configured as a soft tip, which in some embodiments, can be composed of a soft sleeve that is affixed on and that extends beyond distal end  202 , or, alternatively, that is affixed on and extends beyond the lumen of elongate shaft  200 . Typically, a soft tip is affixed through a welding process, but other affixing techniques are also included within the scope of the present invention, for example, adhesive bonding. Suitable materials for the sleeve can be chosen from any material suitable for producing elongate shaft  200 . The sleeve may be manufactured from a material softer than elongate shaft  200 , and may be formed from the same material as expandable member  300  or from a different material, for example, from any of the materials or combinations of materials described with reference to elongate shaft  200 . In one embodiment, the sleeve is manufactured from a material having the same basic composition as, but a lower Shore durometer hardness than, the expandable member  300  material or the elongate tube  200  material. In another embodiment, the sleeve may be manufactured from a blend of PEBAX 55D and PEBAX 63D polymers. One skilled in the art will recognize that the sleeve may be manufactured from a variety of other materials according to the previous description of materials, for example, a polyurethane, a polyethylene, a polyolefin, a polyimide, a polyamide like Nylon, a block copolymer, or blends, or compositions or dual layers or multi-layers thereof. 
     III. The Expandable Member 
     In accordance with one embodiment of the invention, expandable member  300  is a polymeric balloon. Preferably, balloon  300  is a compliant balloon. Unlike a typical angioplasty balloon, which is configured to provide a new circular, open lumen, the polymeric balloon  300  of the embodiment should be sufficiently compliant to mold to the anatomy of the blood vessel. In this manner, balloon  300  can occlude a blood vessel having a diameter from about 2 mm to about 30 mm depending on whether the application is for the coronary, cerebral or peripheral blood vessels. In one embodiment, the balloon can occlude a blood vessel having a diameter from about 2 to about 4.5 mm for coronary or cerebral applications, with a pressure of about 0.5 to 2 atm. For peripheral applications, the balloon can occlude a blood vessel having a diameter from about 4 to about 30 mm, or any luminal orifice of the human body where occlusion of fluid flow could be therapeutic. 
     In one embodiment, the balloon is a one-size-fits-all balloon. In this regard, the balloon must be formed from a compliant polymeric material. For example and not limitation, the compliant balloon  300  can elongate when it is inflated within a narrow sized vessel, and can have a spherical shape when it inflated within a larger or wider blood vessel. Thus, the balloon is capable of molding to the blood vessel. Accordingly, the physician does not need to measure the artery of a patient prior to postconditioning to size balloon  300  to the patient. 
     In one embodiment, balloon  300  is mounted to elongate shaft  200  of the catheter. Balloon  300  contains a hollow interior portion defining an inflation passage extending longitudinally therethrough to receive inflation fluid from inflation lumen  203  of elongate shaft  200 . In one embodiment, the proximal portion of balloon  300  can be configured to taper radially inward at the proximal end and distal end of balloon  300 . The proximal end and the distal end of balloon  300  are sized to mount and seal to respective portions of elongate shaft  200 , while the balloon interior portion is configured for selective inflation from an unexpanded first condition to an expanded second condition as shown in  FIG. 4B . Hence, the transverse cross-sectional dimension of balloon  300 , in the expanded condition, is significantly greater than that of the inwardly tapered end portions of proximal end and the distal end of the balloon. 
     When balloon  300  is mounted to elongate shaft  200 , inflation lumen  203  of elongate shaft  200  is in fluid communication with the inflation passage of balloon  300 . Accordingly, by operating the one-touch control system at the proximal end of the catheter system, described below, the interior portion of the expandable member  300  can be selectively inflated from the first condition to the inflated second condition. 
     Distal shaft  202  of the elongate shaft  200  extends through the inflation passage of balloon  300 , where a distal end of the catheter terminates distal to the distal end of the balloon  300 . As best shown in  FIG. 3A , distal shaft  202  extends longitudinally through the interior portion of the balloon  300 , and defines the distal portion of the guidewire lumen  205  where it terminates at a distal port at a distal end of the elongate shaft  200 . Hence, a guidewire (not shown) may extend through guidewire lumen  205  of the elongate shaft  200 , and out through the distal port of the catheter distal end. This passage enables the catheter to be advanced along the guidewire that may be strategically disposed in a vessel. 
     Balloon  300  can be formed in various shapes, as illustrated in  FIGS. 4A and 4B . As shown, the shape of balloon  300  can be spherical, cylindrical, or polygonal. Various polymers may be selected for the formation of balloon  300 , as would be known in the art. However, the balloon material should be sufficiently compliant such that balloon  300  can mold to the shape of the blood vessel. 
     In one embodiment, balloon  300  may be formed from a polyurethane material, such as TECOTHANE® (Thermedics). TECOTHANE® is a thermoplastic, aromatic, polyether polyurethane synthesized from methylene disocyanate (MDI), polytetramethylene ether glycol (PTMEG) and 1, 4 butanediol chain extender. TECOTHANE® grade 1065D is presently preferred, and has a Shore durometer of 65D, an elongation at break of about 300%, and a high tensile strength at yield of about 10,000 psi. However, other suitable grades may be used, including TECOTHANE® 1075D, having a Shore hardness of about D75. Other suitable compliant polymeric materials include ENGAGE® (DuPont Dow Elastomers (an ethylene alpha-olefin polymer) and EXACT® (Exxon Chemical), both of which are thermoplastic polymers, elastomeric silicones, and latexes. 
     The compliant material may be crosslinked or uncrosslinked. The presently preferred polyurethane balloon materials are not crosslinked. By crosslinking the balloon compliant material, the final inflated balloon size can be controlled. 
     Conventional crosslinking techniques can be used including thermal treatment and E-beam exposure. After crosslinking, initial pressurization, expansion, and preshrinking, the balloon will thereafter expand in a controlled manner to a reproducible diameter in response to a given inflation pressure. 
     In one embodiment, balloon  300  is formed from a low tensile set polymer such as a silicone-polyurethane copolymer. Preferably, the silicone-polyurethane is an ether urethane and more specifically an aliphatic ether urethane such as PURSIL AL 575A and PURSIL AL10 (Polymer Technology Group), and ELAST-EON 3-70A (Elastomedics), which are silicone polyether urethane copolymers, and more specifically, aliphatic ether urethane cosiloxanes. 
     In an alternative embodiment, the low tensile set polymer is a diene polymer. A variety of suitable diene polymers can be used such as but not limited to an isoprene such as an AB and ABA poly(styrene-block-isoprene), a neoprene, an AB and ABA poly(styrene-block-butadiene) such as styrene butadiene styrene (SBS) and styrene butadiene rubber (SBR), and 1,4-polybutadiene. The diene polymer can be an isoprene including isoprene copolymers and isoprene block copolymers such as poly(styrene-block-isoprene). A presently preferred isoprene is a styrene-isoprene-styrene block copolymer, such as Kraton 1161K available from Kraton, Inc. However, a variety of suitable isoprenes can be used including HT 200 available from Apex Medical, Kraton R 310 available from Kraton, and isoprene (i.e., 2-methyl-1,3-butadiene) available from Dupont Elastomers. Neoprene grades useful in the invention include HT 501 available from Apex Medical, and neoprene (i.e., polychloroprene) available from Dupont Elastomers, including Neoprene G, W, T and A types available from Dupont Elastomers. 
     In one embodiment, the polymeric material is a compliant material such as, but not limited to, a polyamide/polyether block copolymer (commonly referred to as PEBA or polyether-block-amide). Preferably, the polyamide and polyether segments of the block copolymers may be linked through amide or ester linkages. The polyamide block may be selected from various aliphatic or aromatic polyamides known in the art. Preferably, the polyamide is aliphatic. Some non-limiting examples include nylon 12, nylon 11, nylon 9, nylon 6, nylon 6/12, nylon 6/11, nylon 6/9, and nylon 6/6. Preferably, the polyamide is nylon 12. The polyether block may be selected from various polyethers known in the art. Some non-limiting examples of polyether segments include poly(tetramethylene glycol), tetramethylene ether, polyethylene glycol, polypropylene glycol, poly(pentamethylene ether) and poly(hexamethylene ether). Commercially available PEBA material may also be utilized such as for example, PEBAX® materials supplied by Arkema (France). Various techniques for forming a balloon from polyamide/polyether block copolymer are known in the art. One such example is disclosed in U.S. Pat. No. 6,406,457 to Wang, the disclosure of which is incorporated by reference. 
     In another embodiment, the balloon material is formed from polyamides. Preferably, the polyamide has substantial tensile strength, is resistant to pin-holing even after folding and unfolding, and is generally scratch resistant, such as those disclosed in U.S. Pat. No. 6,500,148 to Pinchuk, the disclosure of which is incorporated herein by reference. Some non-limiting examples of polyamide materials suitable for the balloon include nylon 12, nylon 11, nylon 9, nylon 69 and nylon 66. Preferably, the polyamide is nylon 12. In yet another embodiment, balloon  300  is composed of several different layers, each one being a different polyamide or polyamide/polyether block copolymer. 
     In accordance with some embodiments, balloon  300  can be composed of a single polymeric layer, or alternatively, can be a multilayered balloon, such as those described in U.S. Pat. No. 5,478,320 to Ishida, U.S. Pat. No. 5,879,369 to Trotta, or U.S. Pat. No. 6,620,127 to Lee, the disclosures of which are incorporated herein by reference. 
     IV. The Handle and Fluid Circuit 
     As described above, the catheter system includes a handle  100  generally disposed at or near the proximal end of the catheter. Handle  110  can include a housing of various shapes and configurations, as shown in  FIGS. 5C to 5R . In one embodiment, handle  100  is non-removably attached to the catheter such that the system is a unitary device requiring assembly prior to use. In other words, the catheter system can be sold in a “ready-to-use” state, unlike conventional angioplasty catheters as described above. 
     The fluid circuit generally includes the inflation and independent deflation lumen disposed along the catheter shaft  200 , a control system disposed in the handle  100  and a plurality of valves to control and regulate pulsated and/or modulated flow of inflation fluid through the catheter system. 
     In some embodiments, elongate shaft  200  includes an inlet port and an outlet port. The inlet port is pressurized by a flow of inflation fluid from a first reservoir as part of the control system  1000  of the fluid circuit. The inflation fluid flows through inflation lumen  203  of elongate shaft  200 , enters the interior portion of the expandable member  300  via an inlet port. The inflow of the inflation fluid into the interior of expandable member  300  causes it to inflate and occlude the blood flow in the artery when disposed therein. An outlet port disposed on the elongate shaft  200  facilitates deflation of expandable member  300  by providing an opening for the inflation fluid to flow from expandable member  300  to deflation lumen  204  during deflation. 
     The outlet port is configured to facilitate Venturi-assisted flow in deflation lumen  204  to deflate expandable member  300 . For example, inflation lumen  203  and deflation lumen  204  can both be open within expandable member  300 . The inflation fluid can pass from inflation lumen  203 , through expandable member  300 , into deflation lumen  204 . Inflation lumen  203  and the deflation lumen  204  are connected by a series of one-way check valves. In one embodiment, the inflation pressure causes the deflation check valve to stay closed. The pressure buildup ( FIGS. 7 ;  117 , 112 , and  109 ) on the back side of the check valve and pulse valve create a Venturi effect to promote rapid deflation. When the actuator is manipulated to the deflate position, pressure on the back side of a deflation check valve is removed. Thus the check valve opens and expandable member  300  can deflate. The rapid exhaustion of the inflation pressure creates a Venturi effect, i.e. it draws the balloon down, and pulls the inflation fluid along. Thus, in some embodiments, the expandable member is deflated in less than one second, and in some embodiments, less than ¼ of a second. 
     In one embodiment, as depicted in  FIG. 5A , the control system  1000  includes an actuator  107  that is capable of actuating inflation and deflation of expandable member  300  with the ease of a flip of a finger. Actuator  107  can be actuated to sequentially inflate and deflate a balloon for postconditioning applications or other applications. It has been found that reperfusion injury can result from rapid opening of an artery after a period of ischemia or interrupted blood flow, as for example but not limitation during a STEMI or other occlusion. One method for decreasing reperfusion injury is to sequentially start and stop the blood flow in the infracted artery for multiple cycles immediately after reopening the initial flow from the STEMI or other blockage. The present disclosure provides physicians with a system designed to achieve efficient, rapid, reproducible postconditioning. Fluid circuit  110 , including control system  1000 , is designed to allow operation of the system by a single actuator  107  with no other input or electronics required referred to as “one-touch.” Actuator  107  can be configured to include a first position or direction for inflation and a second position or direction for deflation of expandable member  300 . For example, the actuator  107  can be a button ( FIG. 5F ), a switch ( FIG. 5A ), or a lever ( FIG. 5B ), having a momentary direction to actuate inflation and a detentable direction to actuate deflation of the balloon. By limiting physician interaction to only one switch, button, or lever, reproducibility in inflating and deflating expandable member  300  in accordance with the time requirements required for postconditioning can be provided. Accordingly, the fluid circuit design and one-touch actuation provides ease of use for postconditioning, and provides a high degree of reproducibility. Additionally, the device embodied herein allows the physician administering postconditioning to focus on the monitor or other instrumentation, as opposed to necessarily focusing on the device during use. 
     In one embodiment, the inflation fluid is released from the reservoir  101  to regulator or a single pressure check valve, which controls the fluid pressure to the balloon  300 . The regulated inflation fluid flows through an inlet tubing  106  to the actuator  107 , (e.g., switch) which controls the flow of inflation fluid to the pulse valve  113  through a check valve and then to balloon  115 . 
     The pulse valve  113  allows inflation fluid to flow from an inlet port to an outlet port within the valve for a specified period of time. The time can be specified, for example, by sizing the inlet port, outlet port, and opposing spring pressure inside the pulse valve, as described below. As best shown in  FIGS. 6A to 6C , in one embodiment, the pulse valve  113  includes an inner wall  1401  disposed within cylindrical body  1400 . Cylindrical body  1400  has a first end  1410  and opposing second end  1411 . An inner wall  1401  having an inlet port  1406  and an outlet port  1407  is disposed within the body  1400  between first and second ends  1410  and  1411 . Preferably, the inlet port  1406  is larger than the outlet port  1407  such that inflation fluid flows through the inlet port into the cylindrical body between the second end  1411  and inner wall  1401  at a faster rate than that which flows through the outlet port  1407  to the cylindrical body between the first wall  1410  and inner wall  1401 . Accordingly, the amount of inflation fluid entering the inlet port  1406  compared to the amount of inflation fluid exiting the outlet port  1406  causes a buildup of fluid pressure between second wall  1411  and inner wall  1401 . The buildup of pressure consequently applies a force to the inner wall and eventually overcomes the strength of spring  1402  and causes the spring to compress, as shown in  FIG. 6B  as the inner wall is pushed from the pressure buildup. The inner wall  1401  contacts a stop member  1405  disposed within the cylindrical body  1400 . In some embodiments a stop is provided on the inner surface of the cylindrical body. The stop is disposed proximate to an outlet port  115  which leads to a pathway to expandable member, e.g., balloon  300  (not shown). As shown in  FIG. 6C , the inner wall  1401  contacts stop  1405  and becomes axially aligned with outlet port  115  to balloon  300 . When inner wall  1401  is axially aligned with outlet port  115 , the passageway provided by the port is blocked so that no inflation fluid can travel to the expandable member  300 . Accordingly, the pulse valve  113  provides a “fool-proof” actuator. In this regard, the physician even if continually depressing the actuator to inflate the expandable member  300 , cannot further inflate the expandable member because the outlet  115  is blocked by the inner wall  1401 . Thus even if additional attempts at inflation are made, the system must de-energize before more inflation fluid is enabled to pass through the system. Thus, the system can safely control the amount of fluid entering an expandable member. The inflation fluid can be various fluids known in the art. For example, the inflation fluid can be a gas fluid or a liquid fluid. For the purpose of illustration, the inflation fluid can be carbon dioxide or saline. 
     In another embodiment, the fluid circuit includes a Venturi-assisted deflation of the expandable member. In this manner, a vacuum is created to rapidly deflate the inflation fluid from the expandable member. In this regard, when deflation is actuated by the physician, the pulse valve is de-energized, the fluid inside the pulse valve escapes thus relieving the pressure on the back side of a check valve, which creates a Venturi effect that decreases the time to deflate the balloon. In some embodiments, the expandable member deflates in less than about 5 seconds, preferably in less than about 3 seconds. 
     As described herein, the fluid circuit  110  generally includes tubing  106  and a plurality of check valves to modulate flow of the inflation fluid through the fluid circuit and eventually to the inflation lumen of elongate shaft  200 , which is in communication with fluid circuit  110  and expandable member  300  and back through an independent deflation lumen. An exploded view of one embodiment of the fluid circuit is illustrated in  FIG. 7A . Fluid circuit  110  housed in the handle  100 , can include the following component parts: first reservoir  101  to provide high pressure inflation fluid, such as but not limited to a BestWhip (LG) (Genuine Innovations, Part 2042 or 4130) ( FIG. 7B ); a piercing mechanism  103  to controllably tap the first reservoir  101 , such as lance assembly, e.g., SA00102, SA00068, SA00101, or MM235008-21N, MM235008-11N (Genuine Innovations) ( FIGS. 7C-7G , respectively); pressure regulator  104  (e.g., MAR-1 (Clippard) or SA00196 (Genuine Innovations),  FIGS. 7H-7I , respectively) to control pressure from inflation fluid to expandable member  300 . Alternatively, a single pressure check valve or a non-variable pressure regulator can be used such as for example, Qosina-P/N 11582 or “Lee Chek” Part Number CCPI2510014S, ( FIG. 7Q ); connector  105  (not shown) to connect the pressure regulator  104  to tubular member  106 , e.g., UTO-2-PKG (Clippard) ( FIG. 7J ); actuator  107  to control the flow of inflation fluid from first reservoir  101  into expandable member  300 ; e.g., a main switch such as FBV-3DMF (Clippard) ( FIG. 7L ); connector  108  to connect tubular member  106  from pressure regulator  104  to actuator  107 , e.g., CT2-PKG (Clippard) ( FIG. 7K ); flow splitter  109  to split the flow of inflation fluid, e.g., UTO-2002-PKG (Clippard) ( FIG. 7M ); connector  111 , such as, e.g., the CT2-PKG (Clippard) ( FIG. 7N ), to connect flow splitter  109  to pulse valve  113 , such as, e.g., PV-1 (Clippard) ( FIG. 7O ), through tubular member  112  to deliver a volume of controlled pulse of inflation fluid to expandable member  300 ; a connector  114 , such as a rotational connector, e.g., UTO-2-PKG (Clippard) ( FIG. 7P ), to connect pulse valve  113  to a one-way check valve  115  (e.g., CCPI2510000S (Lee Company) or Qosina-P/N 11582 ( FIG. 7Q ) that permits flow of inflation fluid to expandable member and ensures the flow direction of the inflation fluid is one-way only, i.e., from pulse valve  113  to inflation lumen  203  of elongate shaft  200 ; flow splitter  116 , such as, e.g., UTO-2002-PKG (Clippard) ( FIG. 7S ) which is connected to flow splitter  109  through tubular member  117 , wherein flow splitter  109  connects the hose from deflation lumen  204  to pressure indicator  118 ; pressure indicator  118 , such as, e.g., IND-1-WH (Clippard) ( FIG. 7T ), for showing that there is pressure in deflation lumen  204  to ensure expandable member  200  is inflated; double hose barb  119  (not shown), such as C22-PKG (Clippard) ( FIG. 7R ), for connecting check valve  120  to the hose going to the catheter; and check valve  120 , such as CCPI12510000S (Lee Company) ( FIG. 7U ), to ensure the flow direction of inflation fluid from the outlet lumen on the catheter pulse valve to inlet lumen  203 . 
     As illustrated in the block diagram of  FIG. 8A , in operation the inflation fluid, in this example carbon dioxide, flows out from storage in the first reservoir  101  by a piercing mechanism  103 . The inflation fluid flows into a main valve or actuator switch. In some embodiments, the flow of inflation fluid is stopped into and out of the main valve. As shown in  FIG. 8B , the fluid circuit can be configured to allow the inflation fluid to flow across the valve into a second check valve. The gas is allowed to flow, in some embodiments, for about 0.1 seconds. After that time, the second valve can be configured to no longer allow flow of the inflation fluid. The check valve allows flow of the inflation fluid into the balloon but not out of the balloon. A third check valve allows inflation fluid flow out of the balloon, but not into the balloon. The inflation fluid, such as the carbon dioxide gas, has a higher pressure when it flows to the inflation check valve, so the system is locked (inflated) at this time. Further, as depicted in  FIG. 8C , the pressure inside the second valve exhausts, thereby creating a Venturi force, as noted above, which pulls the balloon into a deflated position as all the gas exhausts out from the top of the main valve. The main valve does not allow gas to flow in at this time. Accordingly, the fluid circuit permits the user to sequentially inflate and deflate the expandable member with the ease of rapid succession. The handle may further include a pulse valve to deliver time-controlled, or volume-controlled flow to the balloon  300 . In this regard, the second tubular member may include a one-way check valve to lock the pulse valve delivered carbon dioxide in the expandable member  300 . 
     V. Indicator 
     Deflation lumen, in some embodiments, includes an indicator, such as but not limited to a pressure monitor, which ensures balloon is inflated. In some embodiments the pressure monitor is disposed in-between the balloon and a deflation check valve to ensure the balloon is inflated. For example, if the catheter is kinked and not allowing inflation, then the indicator will not indicate inflated. Additionally, if the catheter has a leak at the balloon, then the indicator will not indicate inflated. Accordingly, the indicator is a true test of balloon inflation. 
     In one embodiment, the indicator  118  ( FIGS. 5A, 7 ) or a pressure marker is disposed at a proximal end of the system. In one embodiment, the indicator  118  includes a projection member associated with the deflation lumen of the system. In some embodiments, the indicator  118  is configured to extend at least partially through handle  100  when pressure is sensed in the deflation lumen of the system. In this manner, the indicator orientation can inform the physician of the state of the expandable member. In other words, when the indicator extends from the handle housing  100  and is visible to the physician due to, for example, pressure, forcing the button to extend then the physician is cognizant of the fact that inflation fluid is in the expandable member. Conversely, non-extension of the indicator from the handle  100  informs the user that the expandable member is not fully inflated. As the indicator is in associated, such as for example, coupled, to the deflation lumen at the proximal end of the system, the indicator cannot indicate or extend until pressure from the inflation fluid has flowed through the inflation lumen, made fluid communication with the expandable member, and returned through the deflation lumen to the proximal section of the system. Thus, indicator  118  cannot indicate pressure unless the expandable member is inflated at the distal section of the catheter system. Advantageously, the indicator is an indication of the true pressure inside the balloon. Conversely, an indicator which is not in direct fluid communication with a deflation lumen will not truly indicate if the balloon is inflated or deflated. 
     VI. Arming the Device 
     In one embodiment, as shown in the cross sectional views of  FIGS. 5A and 5B  and best seen in  FIG. 7 , the control system  1000  of fluid circuit  110  generally includes a first reservoir  101 , such as a container or canister, having stored inflation fluid. The first reservoir  101  can be selected (based on size) to inflate and deflate particular balloons of specified sizes. Accordingly, the size of the reservoir selected can prevent reuse and/or promote safety, especially when the inflation fluid is a pressurized gas such as carbon dioxide. 
     In some embodiments, an arming device  114  ( FIG. 9A ) is disposed proximal to the first reservoir and is configured to arm the device. The arming device can be non-reversible. In this regard, “non-reversible” means that once the device is armed, it cannot be disarmed. The arming device  114  is actuated by the physician prior to use in order to pierce the reservoir  110  which contains the inflation fluid. For example, as depicted in  FIGS. 9A and 9B , when arming device  114  is pushed down, first reservoir  101  is pushed forward and a ratchet located on handle housing  112  engages tab  116 , thus preventing arming device  114  from returning to its original position. The system is armed, thereby allowing the fluid to flow from an opening in first reservoir  101 . 
     Further embodiments of arming device  114  are depicted in  FIGS. 9C-9N . For example, in  FIGS. 6C and 6D , arming device  114  is formed from button  114   a  and wedge  114   b  which are positioned such that a downward force on button  114   a  causes wedge  114   b  to move in a perpendicular direction, thereby advancing first reservoir  101  forward into an armed position by releasing inflation fluid stored in the reservoir  101 . Tab  116  again engages a ratchet located on handle housing  112 , preventing both button  114   a  and wedge  114   b  from returning to their original positions. 
     Lever type safeties  114  are depicted in  FIGS. 9E to 9J . As shown, the physician must move the lever from a first position to a second position in order to advance first reservoir  101  into its armed position. The initial and final position of lever arming device  114  depend solely on the manufacturing requirements of the system. In some embodiments, a ratchet located on the side of handle housing  112  engages the sides of lever arming device  114 , thereby preventing lever arming device  114  from returning to its original position. 
     A pull tab type arming device  114 , as shown in  FIGS. 9K-9L , may also be utilized in accordance with some embodiments of the invention. In such embodiments, pull tab type arming device may be formed from pull tab  114   c  and spring mechanism  114   d . The spring is biased in a contracted state until the pull tab is removed. By removing pull tab  114   c  from handle  100 , spring mechanism  114   d  is allowed to expand such that the spring applies a force that pushes or otherwise allows first reservoir  101  to engage a tapping device such as a lancet to arm the device. 
     In other embodiments, arming device  114  may be a screw type arming device, as depicted in  FIGS. 9M-9N . As shown, threads  114   e , located on arming device  114 , engage an opening in housing  112 . Rotating arming device  114  in the appropriate direction causes arming device  114  to advance forward and advance first reservoir  101  into its armed position. In some embodiments, arming device  114  may contain a locking mechanism (not shown) that prevents first reservoir  101  from being disarmed and/or rotating in the wrong direction. 
     As described the arming device  114  arms the first reservoir  101  by causing engagement of the first reservoir  101  with piercing member  103  ( FIGS. 5B, 7 ) so that the reservoir is tapped or pierced to release the inflation fluid contained in the reservoir housing. The outflow of inflation fluid enters the fluid circuit and eventually flows to the expandable member at the distal section of the catheter body and out from the balloon via an independent deflation lumen. 
     VII. Testing of the Presently Disclosed System 
     A study of the device and method of the present disclosure was conducted in comparison to a conventional angioplasty catheter, and a control group in which no reperfusion was conducted. A total occlusion was established in an artery to simulate an ischemic event, after which comparisons were made between the control group (i.e. no postconditioning), postconditioning via conventional angioplasty catheters, and postconditioning via the presently disclosed technique and apparatus. 
       FIG. 10  illustrates a comparison between the three different sample sets tested. In accordance with an aspect of the disclosed subject matter, and as discussed above, the method and apparatus disclosed herein reduces the amount of steps required for the postconditioning procedure. The reduction in steps, and corresponding reduction in time required to conduct postconditioning allows the physician, or other interventionalist, to focus more of their attention and care on the patient, rather than be preoccupied with an array of steps and device components as required with conventional angioplasty catheters. Particularly, and as shown in  FIG. 10 , the operator of the device of the present disclosure spends 97.5% of the procedure time focused on the patient. This is over a 17% increase over conventional angioplasty catheter procedures. 
     Accordingly, the “PUFF” device disclosed herein requires less procedural steps, and provides a pre-assembled device with a trigger operation which results in a greater amount of physician/interventionalist focus on the patient. In one experiment, over 8 cycles of 30-second Postconditioning (8×30 sec inflated, 8×30 sec deflated) were performed totaling 480 seconds. The device of the present disclosure allows the operator to focus 468 seconds on the patient (12 seconds looking away from the monitors), while a conventional Angioplasty-Indeflator device allows the operator to focus 428 total seconds (52 seconds looking away from the monitor and other important instruments during the care of a patient. Moreover, the apparatus of the present disclosure can be operated by a single physician/interventionalist whereas conventional over-the-wire angioplasty devices may require two physicians to operate due (to the need to remove the guidewire during delivery of fluids.) 
     In accordance with another aspect of the present disclosure, the inflation and deflation of the balloon can be controlled via a trigger or button as described above. This is advantageous in that it allows for rapid occlusion and deocclusion, and thus shorter reperfusion cycle times.  FIG. 12  illustrates a comparison of the inflation and deflation times for the apparatus of the present disclosure (“PUFF”) and a conventional angioplasty device (“AngioPC”). As depicted, the apparatus of the present disclosure greatly reduces the time required to both inflate and deflate the balloon, wherein the time to deflate is the time required to restore visible perfusion to the artery, as seen by contrast flow within the lumen. 
     While the disclosed subject matter is described herein in terms of certain preferred embodiments, those skilled in the art will recognize that various modifications and improvements may be made to the disclosed subject matter without departing from the scope thereof. Moreover, although individual features of one embodiment of the disclosed subject matter may be discussed herein or shown in the drawings of the one embodiment and not in other embodiments, it should be apparent that individual features of one embodiment may be combined with one or more features of another embodiment or features from a plurality of embodiments. 
     In addition to the specific embodiments claimed below, the disclosed subject matter is also directed to other embodiments having any other possible combination of the dependent features claimed below and those disclosed above. As such, the particular features presented in the dependent claims and disclosed above can be combined with each other in other manners within the scope of the disclosed subject matter such that the disclosed subject matter should be recognized as also specifically directed to other embodiments having any other possible combinations. Thus, the foregoing description of specific embodiments of the disclosed subject matter has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosed subject matter to those embodiments disclosed. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the method and system of the disclosed subject matter without departing from the spirit or scope of the disclosed subject matter. Thus, it is intended that the disclosed subject matter include modifications and variations that are within the scope of the appended claims and their equivalents.