Abstract:
An inflation system having two pressure vessels integrated into a balloon catheter. A pressurized chamber and a vacuum chamber are integrally attached to proximal end of the balloon catheter and activated by a common valve or switch. Pressure or vacuum is selectively transmitted to the balloon depending on the valve/switch position. The working fluid may be air, or a combination of air and saline with an intermediate piston/cylinder assembly. The balloon catheter may be a part of a heart valve delivery system with a balloon-expandable heart valve crimped onto the balloon.

Description:
RELATED APPLICATIONS  
       [0001]    The present application claims priority under 35 U.S.C. §119 to U.S. Provisional Application Ser. No. 61/871,240, filed Aug. 28, 2013. 
     
    
     FIELD OF THE INVENTION  
       [0002]    The present invention generally relates to balloon catheters and, in particular, to an integrated inflation system for balloon catheters. 
       BACKGROUND OF THE INVENTION 
       [0003]    Balloon dilatation catheters are used for a variety of procedures in which a body lumen or vessel is dilated. For example, such catheters are used in percutaneous transluminal angioplasty procedures in which a stenosed region of an artery, such as a coronary artery, is widened by inserting a deflated balloon into the stenosis and then inflating the balloon under pressure to forcibly enlarge the lumen through the artery. After a brief period of time, the balloon is deflated and removed. Such catheters typically have an elongate flexible shaft and a balloon mounted at the distal end of the shaft. The shaft has a balloon inflation lumen that provides fluid communication between the proximal end of the catheter and the interior of the balloon at the distal end of the shaft. 
         [0004]    Balloon catheters are typically actuated by manual syringes, often called “inflators” (or inflation devices), which use a plunger that is manually advanced using a rod that is threaded into a handle to allow the operator to advance the plunger using very small, controlled increments. Some syringes include a pressure gauge, but the gauge is often located on the syringe itself, and it therefore may be impractical for the physician to monitor the gauge as he or she tries to also watch an image of the balloon being inflated on a monitor. The process for setting up and operating a manual balloon inflation syringe creates logistical difficulties. 
         [0005]    Automatic injection devices, such as described in U.S. Pat. No. 6,099,502, are known for delivering fluids such as saline and contrast agents through a catheter to a patient. The devices typically include a motor-driven linear actuator that forces a plunger through a syringe, thereby creating a desired fluid flow into the patient. For sanitation purposes, the syringe and all associated tubing between the patient and the syringe are disposable, which increases the expense of the system. Further, preparing the automatic injection device for operation can be a time-consuming process. Various tubes may need to be connected together and to the device. The operator preparing the injection device for operation must often be careful to ensure that the connections are tight and that none of the tubes are pinched or otherwise blocked. 
         [0006]    Although numerous configurations are available for inflating balloon catheters, there is a need for a simpler system. 
       SUMMARY OF THE INVENTION 
       [0007]    An integrated inflation system having two pressure vessels integrated into a balloon catheter. A pressurized chamber and a vacuum chamber are integrated within the proximal end of the balloon catheter and activated by a common valve or switch. Pressure or vacuum is transmitted to the balloon depending on the valve/switch position. 
         [0008]    In one embodiment, a balloon catheter system having an integrated inflation subsystem, comprises a manifold having internal passages and a pressurized vessel integrated with an inflation port in the manifold. A balloon catheter has a balloon on a distal end in fluid communication with an inflation lumen extending through the catheter, which in turn is in fluid communication with a balloon port in the manifold. A control valve on the manifold is configured to selectively open and close fluid communication between the balloon port and the inflation port so that a positive pressure differential from the pressurized vessel inflates the balloon. The system may further include a vacuum vessel integrated with a vacuum port in the manifold, wherein the control valve is also configured to selectively open and close fluid communication between the balloon port and the vacuum port so that a negative pressure differential from the vacuum vessel deflates the balloon. 
         [0009]    In accordance with another aspect, a manufactured balloon catheter system includes a balloon catheter having a balloon on a distal end in fluid communication with an inflation lumen extending through the catheter, and an integrated inflation system assembled and packaged with the balloon catheter. The integrated inflation system has a manifold with internal passages, a pressurized vessel integrated with an inflation port in the manifold, a vacuum vessel integrated with a vacuum port in the manifold, and a balloon port in the manifold in fluid communication with the balloon catheter inflation lumen. Finally, a control valve on the manifold selectively opens fluid communication between the manifold port and one or the other of the pressurized vessel and vacuum vessel. 
         [0010]    In a preferred embodiment, the balloon catheter system is part of a prosthetic heart valve delivery system including a balloon-expandable heart valve crimped onto the balloon. Desirably, the pressurized vessel and the vacuum vessel are permanently attached to the manifold, such as via adhesion or thermal welding. In a preferred version, the manifold opens to just the balloon port, inflation port and vacuum port, and the control valve is a stopcock mounted for rotation on the manifold into three positions. The system may further include a pressure regulator located between the control valve and the balloon to limit a balloon pressure to a predetermined maximum. Preferably, the pressurized vessel holds air, and the system may further include a piston/cylinder assembly incorporated into the manifold on which the pressurized air acts and saline is provided in the system distal to the piston/cylinder assembly for inflating the balloon. 
         [0011]    A further understanding of the nature and advantages of the present invention are set forth in the following description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The invention will now be explained and other advantages and features will appear with reference to the accompanying schematic drawings wherein: 
           [0013]      FIG. 1  is a top plan view of a prosthetic heart valve delivery system including a balloon catheter and introducer combination, with an integrated inflation system on the proximal end of the balloon catheter; 
           [0014]      FIG. 2  shows the prosthetic heart valve delivery system with the balloon catheter advanced relative to the introducer to position an expansion balloon within a heart valve stent; 
           [0015]      FIG. 3  shows inflation of the balloon to expand the heart valve stent by opening communication between a pressure vessel and the balloon; and 
           [0016]      FIG. 4  shows deflation of the balloon for withdrawal from within the heart valve stent by opening communication between a vacuum vessel and the balloon. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    The present application discloses an integrated inflation system for a balloon catheter. The inflation system can be coupled to any type of balloon catheter, including but not limited to those used for angioplasty, vascular stent expansion, or as in the illustrated embodiment, expansion of a prosthetic heart valve stent. The term “integrated” refers to a manufactured assembly of components that enable rapid inflation and deflation of the balloon of the catheter. An integrated system is not simply an assembly of components, but rather components that have been pre-assembled during the fabrication process so that they are packaged and sold as a single, unitary system. In this sense, “integrated” contemplates systems that are pre-assembled as one product, and packaged and stored in a unique enclosure as opposed to two or more. Thus, an integrated system arrives at the operating site complete with no further connections needed. The components may be “permanently” joined together, such as by being adhered or thermal welded together so that they cannot be separated without damaging the system, though the components can also be connected together through less permanent means such as with threaded connectors or the like. Other “permanent” connections include a configuration where the components are molded together as one piece, or where some components are “within” larger components, such as where a pressure vessel is positioned within a manifold. Of course, “permanently” connecting components does not mean that they cannot ever be separated, such as with brute force, but rather that they are not intended to be separated and that separation will damage their ready functionality in some way. 
         [0018]      FIG. 1  illustrates a prosthetic heart valve delivery system  20  having an integrated inflation system  22  on the proximal end of a balloon catheter  24  which terminates on a distal end in an expandable balloon  26 . In the illustrated system  20 , the balloon catheter  24  slides linearly within a handpiece of an introducer  28 . The introducer  28  also has a malleable handle shaft  29  leading to a distal locking sleeve  30 . The locking sleeve  30  couples to a valve holder  32  that in turn secures a prosthetic heart valve  34  having a distal anchoring stent  36 . The entire system has a length from the proximal end of the inflation system  22  to the tip of the balloon  26  that may vary depending on the implant technique. For example, devices for surgical valve replacement require relatively short catheters, perhaps between about 200 and 400 mm. On the other hand, so-called “direct-access” devices for beating heart surgeries enter the body through a port in the chest and are routed essentially directly to the heart, requiring somewhat longer catheters, perhaps 300 to 600 mm. Finally, transfemoral deliveries that enter through the leg and pass through the vasculature require much longer catheters, often between 100-200 cm. 
         [0019]    The balloon  26  is initially retracted within the introducer  28  and heart valve  34 , and distal movement of the balloon catheter  24  as seen in  FIG. 2  moves the balloon  26  into a predetermined position to enable expansion of the heart valve stent  36 . As will be explained, inflation of the balloon  26  expands the heart valve stent  36  outward into contact with surrounding anatomy. The prosthetic heart valve delivery system  20  is particularly well-suited for implanting a prosthetic aortic valve at an aortic annulus, with the stent  36  positioned sub-annularly, against the left ventricular wall adjacent the aortic valve annulus. Additional details of the exemplary valve deployment system  20  and method of use are disclosed in U.S. Pat. No. 8,641,757, filed Jun. 23, 2011, the contents of which are expressly incorporated by reference herein. A commercial system having many of the same components is sold as the EDWARDS INTUITY valve system by Edwards Lifesciences Corp. of Irvine, Calif. 
         [0020]    The integrated inflation system  22  includes a junction manifold  38  having internal passages and at least three inlet/outlet ports, one of which connects to the proximal end of the balloon catheter  24  (a balloon port). A second inlet/outlet port, or inflation port, of the manifold  38  connects to a sealed pressure vessel  40 , while a third inlet/outlet port, or vacuum port, connects to a sealed vacuum vessel  42 . A control valve in the form of a stopcock  44  mounted in the manifold  38  controls which of the inlet/outlet ports are in fluid communication. In a preferred embodiment the manifold  38  opens to just the balloon port  24 , inflation port, and vacuum port, and the control valve is a manual stopcock mounted for rotation on the manifold into three positions. It should be understood that the stopcock  44  represents a fluid control valve that can be an electromechanical valve having a switch, solenoids, or other such devices, and thus the term “control valve” should not be considered limited to a purely mechanical/manual stopcock. The inflation system  22  further includes a pressure regulator  46  interposed between the manifold  38  and the balloon catheter  24 . The pressure regulator  46  functions to sense pressure in the lumen of the balloon catheter  24  and close upon reaching a threshold pressure. 
         [0021]    The particular pressure used to inflate the balloon  26  varies depending on the application. For instance, the exemplary pressure used in the EDWARDS INTUITY valve system is between about 4.5-5 atmospheres (0.46-0.51 MPa). Other systems may require more or less pressure, such as up to 7 atm (0.71 MPa), or may utilize a volume based inflation criteria to achieve a specific diameter. In the latter case, the pressure regulator  46  may be replaced or supplemented with a volumetric flow meter that indicates total volume delivered as opposed to pressure. 
         [0022]      FIGS. 3 and 4  illustrate expansion and deflation of the balloon  26  to expand the anchoring stent  36 . Initially, the stopcock is in a neutral position in between plus (+) and minus (−) signs printed, inscribed or embossed on the manifold  38 . The neutral position closes off communication between any two ports of the manifold  38 . The plus sign lies toward the pressure vessel  40 , while the minus sign is adjacent to vacuum vessel  42 . The plus and minus signs correspond respectively to expansion/inflation and contraction/deflation of the balloon  26  on the balloon catheter  24 . Of course, other indicators such as the colors green and red may be provided on the manifold  38  for the same purpose. Furthermore, the vessels themselves may have the words “Pressure” and “Vacuum” (or Inflate/Deflate) printed, inscribed or embossed thereon, as shown. 
         [0023]      FIG. 3  shows the stopcock  44  rotated counter clockwise toward the pressure vessel  40  so as to open communication between the pressure vessel and the balloon catheter  24 , thus causing the balloon  26  to inflate and expand, deploying the anchoring stent  36  against the annulus. The anchoring stent  36  transitions between its conical contracted state seen in  FIGS. 1-2 , and its generally tubular or slightly conical expanded state seen in  FIGS. 3-4 . Simple interference between the anchoring stent  36  and the annulus may be sufficient to anchor the heart valve  34 , or interacting features such as projections, hooks, barbs, fabric, etc. may be utilized. Further, the heart valve  34  may have a sealing ring  37  which can be secured to the annulus using sutures, barbs, etc. 
         [0024]      FIG. 4  shows the stopcock  44  rotated clockwise toward the vacuum vessel  42  which opens communication between the vacuum vessel and the balloon catheter  24 . This communicates a reduced or negative pressure to the interior of the balloon  26 , causing its deflation as shown. Deflation of the balloon  26  facilitates its removal from within the heart valve and the delivery system in general. It should be noted that not all balloon inflation systems require active deflation as shown. In those systems, a simple valve that enables passive deflation of the balloon pressure to the atmosphere may be provided. The vacuum vessel  42  could thus represent such a valve. While that may work with air as the working fluid, for saline it would be preferred to deflate the balloon actively. 
         [0025]    The exemplary delivery system balloon  26  has a relatively high diameter-to-length ratio compared to other surgical balloons, such as those used to expand cardiovascular stents. This makes it particularly difficult for the balloon  26  to return to a small geometry upon deflation after deployment. Balloons of such size ratios tend to “butterfly” by forming wings that prevent removal through the valve  34  and its holder  32  without the application of high forces, which may cause damage to the valve itself. The exemplary balloon  26  thus preferably includes a series of longitudinal pleats heat set into its wall to facilitate self-collapse during deflation. Further, the distal end of the balloon  26  moves relative to the proximal end to enable lengthening of the balloon during deflation. This lengthening occurs automatically by virtue of an internal wire (not shown) which is spring-biased to stretch the balloon longitudinally. These components are also shown in U.S. Pat. No. 8,641,757. It should be noted that easy deflation and removal of the balloon  26  permits rapid replacement of the balloon catheter in case of a problem, such as insufficient inflation. 
         [0026]    In the most basic configuration, the integrated inflation system  22  uses air as the working fluid to expand the balloon  26 . However, air is typically only compatible for open procedures. In applications where controlled, pressurized, sterile physiologic saline is the working fluid, the system may require a dynamic piston against which air acts to cause the piston to displace the saline into the balloon  26 . One of skill in the art will understand that such a piston/cylinder assembly can easily be incorporated into the manifold  38  between the stopcock  44  and the pressure regulator  46 , such as shown schematically at  50  in  FIG. 3 . 
         [0027]    The integrated inflation system  22 , and in particular the pressure vessels  40 ,  42 , are manufactured using metallic or polymer-based components, depending on the pressure loads. Desirably, the system  22  is assembled at the time of manufacture and packaged with the delivery system  20 . As such, the pressure vessels  40 ,  42  will be required to maintain their respective internal pressures over long periods, sometimes years. Consequently, special seals between the pressure vessels  40 ,  42  and the manifold  38 , and between the manifold  38  and the balloon catheter  24 , are required. For example, the seals at the outlet of a recreational CO 2  cartridge may be suitable. Alternatively, welded or elastomeric seals which can be punctured or otherwise compromised at the time of use may be provided. Another solution is to provide a robust valve at the inlet/outlet of each pressure vessels  40 ,  42  that can be manually opened after the system has been removed from its sterile packaging just prior to use, thus initiating fluid communication between the vessels and the manifold  38  and stopcock  44 . 
         [0028]    While the invention has been described in its preferred embodiments, it is to be understood that the words which have been used are words of description and not of limitation. Therefore, changes may be made within the appended claims without departing from the true scope of the invention.