Patent Publication Number: US-2022218959-A1

Title: Intravascular balloon with slidable central irrigation tube

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to prior filed U.S. Provisional Application No. 63/137,270 filed on Jan. 14, 2021 which is hereby incorporated by reference as set forth in full herein. 
    
    
     FIELD 
     The present invention relates to medical instruments, and in particular balloon catheters. 
     BACKGROUND 
     Some intravascular treatments utilize balloon catheters having an inflatable balloon near a distal end of the catheter. There are a variety of balloon catheter designs usable for various purposes where, generally, the balloon is collapsible to traverse vasculature and expandable within a blood vessel and/or heart. Typically, the balloon is inflated and deflated by pumping a fluid (e.g. saline solution) through an inflation tube and/or lumen of the catheter. Some balloon catheters can further provide irrigation through pores in the balloon, where such porous balloons are referred to herein as an “irrigation balloon”. 
     Some irrigation balloons include electrodes for sensing and/or ablation such as described in U.S. Patent Application Publication 2020/0155226, U.S. Patent Application Publication 2019/0298441, and U.S. Pat. No. 7,410,486, each incorporated by reference herein. Such irrigation balloons can be used in treatments involving catheter ablation of cardiac arrhythmias. The irrigation balloon catheter can provide fluid for controlling temperature of blood and/or tissue during ablation, for instance. 
     Generally, larger volume balloons can require longer inflation and deflation times compared to smaller volume balloons. In some irrigation balloons, pores in the balloon can allow fluidic ingress into the irrigation balloon absent negative pressure, which may allow the balloon to at least partially expand when deflated. Some irrigation balloons include a mechanism within and/or attached to the irrigation balloon to facilitate inflation and/or deflation of the irrigation balloon. See, for example, U.S. Patent Application Publication 2018/0140807, U.S. Patent Application Publication 2018/0161093, U.S. Patent Application Publication 2019/0059818, U.S. Patent Application Publication 2019/0201669, U.S. Patent Application Publication 2019/0217065, U.S. Patent Application Publication 2020/0147295, and U.S. Pat. No. 9,907,610, each incorporated by reference herein. Such irrigation balloons can also include electrodes for sensing and/or ablation. 
     SUMMARY 
     Examples presented herein generally include a balloon catheter having a central tube that is configured to both structurally support and inflate a balloon membrane, methods of use, and methods of construction of the same. The central tube has a lumen and inflation ports that provide a flow path for inflating the balloon. The central tube allows the balloon membrane to be inflated without requiring an additional inflation tube inserted under the balloon membrane. The lumen of the central tube is obstructed by a distal end piece, nose piece, or other structure to prevent fluid from exiting a distal end of the central tube. The central tube is configured such that, during inflation, inflation media is allowed to pass through an elongated shaft of the catheter, into a proximal open end of the central tube, and through the inflation ports into the balloon. The central tube can be configured to slide longitudinally in relation to the shaft to longitudinally elongate and/or truncate the balloon. The balloon catheter can include various sensors and electrodes to function with cardiac mapping and/or ablation systems. 
     An example balloon catheter can include an elongated shaft, an inflatable balloon, a central tube, and an end plug. The elongated shaft extends along a longitudinal axis of the balloon catheter. The inflatable balloon can be disposed approximate a distal end of the shaft. The end plug can be disposed approximate a distal end of the central tube. 
     The inflatable balloon can have an interior configured to receive an inflation medium to inflate the inflatable balloon. A distal end of the inflatable balloon can be affixed to the central tube. A proximal end of the inflatable balloon being affixed to the shaft. 
     The central tube can extend along the longitudinal axis. At least a portion of the central tube can be positioned within the inflatable balloon, provide structural support for the inflatable balloon, include inflation ports, and have a central lumen in fluidic communication with the inflation ports. The central tube can be coupled to the distal end of the shaft so that the central tube is movable to extend and/or contract the inflatable balloon in length in relation to the longitudinal axis. 
     The central lumen and inflation ports can provide a flow path between the inflatable balloon interior and the shaft to allow the inflation medium to pass from the shaft into the interior of the inflatable balloon. The central lumen can include an opening positioned in a proximal direction in relation to the inflation ports and in fluidic communication with the shaft to allow the inflation medium to travel from the shaft into the central lumen. 
     The central lumen can be obstructed by an obstruction at a position distal to the inflation ports so that inflation medium is inhibited from moving through the central lumen distal of the obstruction. The end plug can be configured to prevent loss of fluid through the distal end of the tube. The end plug and the obstruction can be one in the same. 
     The balloon catheter can further include a collapsing set of splines and a membrane affixed to the splines. The splines can be made at least partially from a shape-memory material having a collapsed pre-formed shape that collapses the inflatable balloon. The inflatable balloon can include the membrane. 
     The balloon catheter can further include an elastic element and a puller-wire. The elastic element can be coupled to the central tube and shaft. The elastic element can be configured to self-elongate thereby sliding the central tube distally in relation to the shaft and extending the inflatable balloon in length in relation to the longitudinal axis. The puller-wire can be connected to the central tube, extend through the shaft, and be accessible for retraction during treatment so that retraction of the puller-wire compresses the elastic element in the direction of the longitudinal axis thereby sliding the central tube in relation to the shaft and contracting the inflatable balloon in length in relation to the longitudinal axis. 
     The balloon catheter can further include a fluid impermeable seal between the central tube and the shaft, disposed over the central tube and within the shaft. 
     The balloon catheter can further include a navigation sensor disposed within the central lumen. The navigation sensor can be a three axis inductive sensor. The navigation sensor can be positioned in a distal direction in relation to the inflation ports. The balloon catheter can further include a sensor wire in electrical communication with the navigation sensor and extending through at least a portion of the central lumen. 
     The balloon catheter can further include irrigation ports disposed on or over the inflatable balloon. The balloon catheter can be configured to irrigate via the irrigation ports. The irrigation ports can be positioned on the inflatable balloon so that the flow path extends from the shaft, through the central lumen, through the inflation ports, through the interior of the inflatable balloon, and through the irrigation ports. The balloon catheter can further include a plurality of electrodes disposed on the outer surface of the inflatable balloon and one or more wires connected to each of the plurality of electrodes. Each wire can extend through the shaft. 
     As an alternative to the inflation balloon being also an irrigation balloon, the balloon catheter can include an irrigation balloon comprising irrigation ports and being disposed over the inflatable balloon so that inflation of the inflatable balloon at least partially inflates the irrigation balloon. The balloon catheter can include a chamber between the irrigation balloon and the inflatable balloon that is fluidically separate from the interior of the inflatable balloon and in fluidic communication with the irrigation ports. The balloon catheter can further include a plurality of electrodes disposed on the outer surface of the irrigation balloon and one or more wires connected to each of the plurality of electrodes, each wire extending through the shaft. 
     An example method can include some or all of the following steps that can be executed in various orders, and the method can include additional steps not listed. The method can include inflating an inflatable balloon of a balloon catheter through a flow path that traverses an elongated shaft of the balloon catheter, a central lumen of a central tube positioned within the inflatable balloon, inflation ports of the central tube, and an interior of the inflatable balloon. The method can include structurally supporting the inflatable balloon along a longitudinal axis of the balloon catheter with the central tube, the central tube being aligned with the longitudinal axis so that at least a portion of the central tube is positioned within the inflatable balloon. 
     The method can include sliding the central tube in relation to the shaft to thereby extend and/or contract the inflatable balloon in length in relation to the longitudinal axis. 
     The method can include collapsing a set of splines made at least partially from a shape-memory material having a collapsed pre-formed shape that collapses the inflatable balloon. 
     The method can include extending the inflatable balloon in length in relation to the longitudinal axis by allowing an elastic element coupled to the central tube and shaft to self-elongate thereby sliding the central tube longitudinally in relation to the shaft. The method can include retracting the inflatable balloon in length in relation to the longitudinal axis by retracting a puller-wire connected to the central tube and extending through the shaft thereby compressing the elastic element in the direction of the longitudinal axis and sliding the central tube longitudinally in relation to the shaft. 
     The method can include inhibiting, by a distal end piece of the catheter, inflation medium from exiting a distal end of the central lumen. 
     The method can include traversing, with the flow path, an opening in the central tube, the opening being in fluidic communication with the central lumen, in fluidic communication with the shaft, and positioned in a proximal direction from the inflation ports. 
     The method can include determining a position of the inflatable balloon based on electrical signals provided by a navigation sensor disposed within the central lumen. The navigation sensor can be a three axis inductive sensor. 
     The method can include positioning the navigation sensor in a distal direction in relation to the inflation ports. 
     The method can include receiving the electrical signals via a sensor wire in electrical communication with the navigation sensor and extending through at least a portion of the central lumen. 
     The method can include irrigating through irrigation ports disposed on or over the inflatable balloon. 
     The method can include positioning the irrigation ports on the inflatable balloon so that the flow path extends from the shaft, through the central lumen, through the inflation ports, through the interior of the inflatable balloon, and through the irrigation ports. The method can include receiving and/or providing electrical signals to a plurality of electrodes disposed on the outer surface of the inflatable balloon via one or more wires connected to each of the plurality of electrodes, each wire extending through the shaft. 
     As an alternative to positioning irrigation ports on the inflatable balloon, the method can include disposing the irrigation ports on an irrigation balloon. The method can include disposing the irrigation balloon over the inflatable balloon. The method can include inflating the inflatable balloon to at least partially inflate the irrigation balloon. The method can include fluidically separating the irrigation balloon and the interior of the inflatable balloon with a chamber therebetween. The method can include fluidically communicating the chamber with the irrigation ports. The method can include receiving and/or providing electrical signals to a plurality of electrodes disposed on the outer surface of the irrigation balloon via one or more wires connected to each of the plurality of electrodes, each wire extending through the shaft. 
     Another example method can include some or all of the following steps that can be executed in various orders, and the method can include additional steps not listed. The method can include coupling a central tube to a distal end of an elongated catheter shaft so that the central tube has a central lumen in fluidic communication with the catheter shaft and so that inflation ports on the central tube are in fluidic communication with the central lumen and thereby the shaft. The method can include affixing an inflatable balloon approximate a distal end of the shaft and over at least a portion of the central tube so that the inflation ports are positioned within an interior of the inflatable balloon and the inflatable balloon is configured to receive inflation medium through a flow path that extends through the shaft, through the central lumen, and through the inflation ports into the interior of the balloon to inflate the inflatable balloon. 
     The method can include coupling the central tube to the distal end of the shaft so that the central tube is movable to extend and/or contract the inflatable balloon in length in relation to the longitudinal axis. 
     The method can include affixing a distal end of the inflatable balloon to the central tube. The method can include affixing a proximal end of the inflatable balloon to the shaft. 
     The method can include forming a set of splines made at least partially from a shape-memory material into a collapsed pre-formed shape. The method can include affixing the set of splines to the balloon catheter in relation to the inflatable balloon such that moving the splines to the collapsed pre-formed shape collapses the inflatable balloon. 
     The method can include coupling an elastic element to the central tube and shaft such the elastic element is configured to self-elongate and cause the central tube to slide in relation to the shaft thereby extending the inflatable balloon in length in relation to the longitudinal axis. The method can include connecting a puller-wire to the central tube. The method can include extending the puller-wire through the shaft so that the puller-wire is accessible for retraction during treatment so that retraction of the puller-wire compresses the elastic element in the direction of the longitudinal axis thereby sliding the central tube proximally in relation to the shaft and contracting the inflatable balloon in length in relation to the longitudinal axis. 
     The method can include obstructing the central lumen at a position distal to the inflation ports so that inflation medium is inhibited from moving through the central lumen distal of the obstruction. 
     The method can include positioning an opening on the central tube to the central lumen in a proximal direction in relation to the inflation ports so that the opening is in fluidic communication with the shaft to allow the inflation medium to travel from the shaft into the central lumen. 
     The method can include disposing a fluid impermeable seal between the central tube and the shaft so that the fluid impermeable seal is over the central tube and within the shaft. 
     The method can include affixing a navigation sensor within the central lumen. The navigation sensor can be a three axis inductive sensor. The method can include affixing the navigation sensor in a distal direction in relation to the inflation ports. The method can include electrically connecting a sensor wire to the navigation sensor. The method can include extending the sensor wire through at least a portion of the central lumen. 
     The method can include configuring the balloon catheter to irrigate through irrigation ports disposed on or over the inflatable balloon. The method can include configuring the inflatable balloon to irrigate through the irrigation ports. 
     The method can include positioning the irrigation ports on the inflatable balloon so that the flow path extends from the shaft, through the central lumen, through the inflation ports, through the interior of the inflatable balloon, and through the irrigation ports. The method can include disposing a plurality of electrodes on the outer surface of the inflatable balloon. The method can include electrically connecting one or more wires to each of the plurality of electrodes. The method can include extending each wire through the shaft. 
     As an alternative to positioning irrigation ports on the inflatable balloon, the method can include disposing an irrigation balloon having irrigation ports over the inflatable balloon so that inflation of the inflatable balloon at least partially inflates the irrigation balloon. The method can include forming a chamber between the irrigation balloon and the inflatable balloon that is fluidically separate from the interior of the inflatable balloon and in fluidic communication with the irrigation ports. The method can include disposing a plurality of electrodes on the outer surface of the irrigation balloon. The method can include electrically connecting one or more wires to each of the plurality of electrodes. The method can include extending each wire through the shaft. 
     Another example catheter can include an elongated shaft, an inflatable balloon, a central tube, and a distal end piece. The elongated shaft can extend from a proximal end to a distal end along a longitudinal axis of the balloon catheter. The inflatable balloon can be disposed approximate the distal end of the shaft. The inflatable balloon can include an interior configured to receive an inflation medium to inflate the inflatable balloon to a first expanded volume defined by a truncated cone having its base connected to a semi-toroid. The central tube can extend along the longitudinal axis. At least a portion of the central tube can be positioned within the inflatable balloon, provide structural support for the inflatable balloon, include inflation ports, and have a central lumen in fluidic communication with the inflation ports. The central lumen and inflation ports can provide a flow path between the inflatable balloon interior and the shaft to allow the inflation medium to pass from the shaft into the interior of the inflatable balloon. The central tube can be configured to move along the longitudinal axis to change the first expanded volume to a second expanded volume defined substantially by two truncated cones connected at their respective bases. 
     The distal end piece can include an end plug (or nose piece) to prevent loss of fluid through the central tube. 
     This example catheter can further include features and structures of the above example catheter. This example catheter can be constructed and/or used according to the above example methods. 
     Steps of the above example methods can be combined in a single method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is an illustration of a distal portion of an example irrigation balloon catheter in a radially expanded, longitudinally retracted state (first inflated state) according to aspects of the present invention. 
         FIG. 1B  is an illustration of the distal portion of the irrigation balloon catheter in a radially expanded, longitudinally extended state (second inflated state) according to aspects of the present invention. 
         FIG. 1C  is an illustration of the distal portion of the irrigation balloon catheter further extended in radially contracted, longitudinally extended state (deflated state) according to aspects of the present invention. 
         FIGS. 2A and 2B  are respectively illustrations of a cross section of the irrigation balloon catheter in the state illustrated in  FIGS. 1A and 1B  in a plane parallel to the viewing plane of  FIGS. 1A and 1B  and mid-way through the catheter. 
         FIG. 3  is an isometric view of the irrigation balloon catheter having cross section through a distal portion of a shaft of the catheter as indicated in  FIG. 1A . 
         FIG. 4A  is an illustration of a distal portion of the example irrigation balloon catheter including an optional expandable conic membrane according to aspects of the present invention. 
         FIG. 4B  is an illustration of an exploded view of the distal portion of the irrigation balloon catheter illustrated in  FIG. 4A . 
         FIG. 5A  is an illustration of a distal portion of another example irrigation balloon catheter in a radially expanded, longitudinally retracted state (inflated state) according to aspects of the present invention. 
         FIG. 5B  is an illustration of the distal portion of the irrigation balloon catheter illustrated in  FIG. 5A  in a radially contracted, longitudinally extended state (deflated state) according to aspects of the present invention. 
         FIG. 6  is an illustration of a distal portion of another example irrigation balloon catheter having collapsible and/or expandable splines according to aspects of the present invention. 
         FIG. 7A  is an illustration of a distal portion of another example irrigation balloon catheter in a radially contracted, longitudinally extended state (deflated state) and having a self-expandable spring according to aspects of the present invention. 
         FIG. 7B  is an illustration of the distal portion of the irrigation balloon catheter illustrated in  FIG. 7A  in a radially expanded, longitudinally retracted state (inflated state) according to aspects of the present invention. 
         FIG. 8  is an illustration of a system for diagnosis and treatment of a heart of a living patient according to aspects of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Documents incorporated by reference herein are to be considered an integral part of the application except that, to the extent that any terms are defined in these incorporated documents in a manner that conflicts with definitions made explicitly or implicitly in the present specification, only the definitions in the present specification should be considered. 
     As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, “about” or “approximately” may refer to the range of values ±20% of the recited value, e.g. “about 90%” may refer to the range of values from 71% to 99%. 
     As used herein, the terms “patient,” “host,” “user,” and “subject” refer to any human or animal subject and are not intended to limit the systems or methods to human use, although use of the subject invention in a human patient represents a preferred embodiment. 
     As used herein, the terms “tubular” and “tube” are not limited to a structure that is a right cylinder or strictly circumferential in cross-section or of a uniform cross-section throughout its length. For example, the tubular structure or system is generally illustrated as a substantially right cylindrical structure. However, the tubular system may have a tapered outer surface, a curved outer surface, and/or a partially flat outer surface without departing from the scope of the present disclosure. 
     Examples presented herein generally include a balloon catheter having a central tube that is configured to both structurally support and inflate a balloon membrane. The central tube can have a lumen and sidewall inflation ports that provide a path for inflating the balloon. The lumen of the central tube can be obstructed by a distal end piece, nose piece, or other structure to prevent fluid from exiting a distal end of the central tube. The central tube can be configured such that, during inflation, inflation media is allowed to pass through an elongated shaft of the catheter, into a proximal open end of the central tube, and through the inflation ports into the balloon. The central tube lumen may be configured to accommodate a larger inner diameter compared to an irrigation lumen of a balloon catheter having a separate support tube and irrigation tube. A larger irrigation lumen can potentially reduce overall back pressure and load on a pump supplying fluid to the balloon. The central tube can further be configured to slide longitudinally in relation to the shaft to longitudinally elongate and/or retract the balloon. 
     The central tube can be attached via the shaft to a luer hub for catheter irrigation. The central tube can be attached to an advancement system within a handle (such as a drive or slider, manually or powered via hydraulic or electrically activated) which an end user (e.g. physician) can use to push the central tube resulting in balloon advancement. Interstitial space around an outer diameter of the central tube can be sealed using a conformal friction seal or bellows or folding sleeve to prevent irrigation at pressure in balloon from entering the proximal section of the catheter including handle. The seal can prevent leaking while allowing advancement of the central tube from the shaft to elongate the balloon. Various types of seals may be suitable for the purpose such as bellows, conformal, O-ring, etc. Balloon membrane can be made from polyethylene terephthalate (PET), polyurethane, polyether block amide, or any other suitable material 
     A navigation sensor (e.g. three axis sensor, “TAS”) can be embedded in the central tube at a position that is distal to the inflation ports. Positioned as such, a sensor wire carrying signals from the navigation sensor can be positioned in the central tube lumen. Positioning of the sensor wire within the central tube lumen can alleviate space constraints within the balloon at a marginal tradeoff of increasing back pressure of inflation fluid. The sensor wire can be brought out of the central tube lumen and sealed in the handle. The sensor wire can be positioned and otherwise configured to provide strain relief to accommodate slack in the handle. 
     Example catheters presented herein can be modified in several manners as understood by a person skilled in the pertinent art according the teachings herein. Irrigation balloons can include electrodes for sensing and/or ablation such as described in U.S. Patent Application Publication 2020/0155226, U.S. Patent Application Publication 2019/0298441, and U.S. Pat. No. 7,410,486, each incorporated by reference herein. Irrigation balloons can include a mechanism within and/or attached to the irrigation balloon to facilitate inflation and/or deflation of the irrigation balloon and/or telescoping of the central tube such as presented in U.S. Patent Application Publication 2018/0140807, U.S. Patent Application Publication 2018/0161093, U.S. Patent Application Publication 2019/0059818, U.S. Patent Application Publication 2019/0201669, U.S. Patent Application Publication 2019/0217065, U.S. Patent Application Publication 2020/0147295, and U.S. Pat. No. 9,907,610, each incorporated by reference herein. Likewise, example catheters presented herein can include additional components such as navigation sensors, thermocouples, a mechanism for deflecting a distal portion of the catheter shaft, a force sensor, and other compatible electrical and mechanical features. Omission of such features from the figures are solely for the sake of clarity in illustration, and any of the depicted example catheters can be modified to include such features as understood by a person skilled in the pertinent art. 
       FIGS. 1A through 1C  are illustrations of a distal portion of an example balloon catheter  100 . The distal portion of the balloon catheter  100  is illustrated in a radially expanded, longitudinally retracted state in  FIG. 1A , a longitudinally extended state in  FIG. 1B , and in a deflated state in  FIG. 1C . 
       FIGS. 2A and 2B  are cross-sectional illustrations of the views of the balloon catheter  100  in  FIGS. 1A and 1B  respectively. 
     Referring collectively to  FIGS. 1A-1C, 2A, and 2B , the balloon catheter  100  includes an elongated shaft  130 , an inflatable balloon  162 , a central tube  102 , and a distal plug  106 . The elongated shaft  130  extends along a longitudinal axis L-L of the balloon catheter  100  and can be manipulated at its proximal end by a handle or other apparatus as understood by a person skilled in the pertinent art. The inflatable balloon  162  is disposed approximate a distal end of the shaft  130 . At least a portion of the central tube  102  is positioned within the inflatable balloon  162  The central tube  102  provides structural support for the inflatable balloon  162 . The central tube  102  includes inflation ports  104 . As better visualized in  FIGS. 2A and 2B , the central tube  102  includes a central lumen  103  in fluidic communication with the inflation ports  104 . The central lumen  103  and inflation ports  104  provide a flow path between the inflatable balloon interior and the shaft  130  to allow the inflation medium to pass from the shaft  130  into the interior of the inflatable balloon  162 . The central tube  102  can move distally along the longitudinal axis L-L to facilitate reshaping of the balloon  162 . The distal plug  106  is positioned at a distal end  126  of the catheter  100  to prevent loss of fluid through a distal end of the central tube  102 . The distal plug  106  has an atraumatic shape. Alternatively, the distal plug  106  can be positioned within the central tube  102 . In such an example, the catheter  100  can have an internal distal end similar to corresponding structures in U.S. 2019/0201669. 
       FIGS. 1A and 2A  illustrate the balloon  162  in a first inflated state inflated to a first expanded volume defined by a truncated cone having its base connected to a semi-toroid. The semi-toroid extends radially and distally from a distal end  188  of the balloon  162  that is attached near a distal end of the central tube  102 ; the semi-toroid then curves proximally to a first circumference C 1  that is a maximum circumference of the balloon  162  in the illustrated shape. The truncated cone has an apex at a proximal end  186  of the balloon  162  that is attached to the shaft  130 ; the truncated cone extends radially and distally from the apex to meet the semi-toroid at the maximum circumference C 1 . The balloon  162  has a first longitudinal dimension, or first height H 1 , measured from the proximal end  186  of the balloon  162  to the distal plug  106 . 
       FIGS. 1B and 2B  illustrate the balloon in a second inflated state inflated to a second expanded volume defined substantially by two truncated cones connected at their respective bases. The balloon  162  can be moved from the first inflated state to the second inflated state and vice versa by sliding the central tube  102  distally and proximally in relation to the shaft  130 . The second volume can be about equal to the first volume. A distal cone has an apex at a distal end  188  of the balloon  162  and extends radially and proximally to a second maximum circumference C 2  of the balloon  162 . A proximal cone has an apex at the proximal end  186  of the balloon  162  and extends radially and distally to meet the distal cone at the second circumference C 2 . The balloon  162  has a second height H 2  measured from the proximal end  186  of the balloon  162  to the distal plug  106 . The second height H 2  is greater than the first height H 1  because the central tube  102  is extended distally from the shaft  130  compared to as illustrated in  FIGS. 1A and 2A . The second circumference C 2  is about equal to or less than the first circumference C 1 . 
       FIG. 1C  illustrates the balloon  162  in a deflated state deflated to a third volume so that the balloon  162  can be repositioned and/or retracted into a catheter. The third volume is significantly less than both the first and second volumes. The balloon  162  is extended to a third height H 3 , measured from the proximal end  186  of the balloon  162  to the distal plug  106 , that is equal to or greater than the second height H 2  illustrated in  FIGS. 1B and 2B , preferably greater than the second height H 2 . When the third height H 3  is greater than the second height H 2 , the central tube  102  is extended distally from the shaft when the balloon is moved from the second inflated state to the deflated state. The balloon  162  has a third maximum circumference C 3  that is less than the first circumference C 1  and the second circumference C 2 . To deflate the balloon  162 , fluid can be extracted from the interior volume of the balloon  162  into the inflation ports  104 , through the central lumen  103  of the central tube  102 , and into the shaft  130  to be pumped out of the catheter  100  with a pump or other such apparatus. 
     In some examples, the maximum height H 3  ( FIG. 1C ) can measure about 45 mm and the minimum height H 1  ( FIG. 1A ) can measure about 38 mm. Heights of about 45 mm to about 38 mm can be useful when performing procedures as illustrated and described in relation to  FIG. 8 , for instance. The heights H 1 , H 2 , H 3  can otherwise be dimensioned to meet the needs of an intravascular procedure as understood by a person skilled in the pertinent art according to the teachings herein. 
       FIGS. 2A and 2B  illustrates a TAS  112  positioned within the central tube  102  distal to the inflation ports  104  and a sensor wire  114  connected to the TAS  112  and extending through the central lumen  103 . 
       FIG. 3  is an isometric view of the catheter  100  where the balloon  162  is in the first inflated state with a cross-sectional view of the shaft  130  as indicated in  FIG. 1A . 
     Referring collectively to  FIGS. 2A, 2B, and 3 , the catheter  100  includes an interim inflation tube  116  that is stepped into the central tube  102 . This stepping can be redesigned so that the inflation tube  116  is an extension of the central tube  102 ; and/or a lumen of the shaft  130  (e.g. lumen  118  in which the inflation tube  116  is positioned as illustrated) provides functionality of the inflation tube  116 . Such alternative designs may further simplify design and construction and improve catheter back pressure. 
     As illustrated in  FIG. 3 , the shaft  130  can include multiple lumens  118 ,  120 ,  122 ,  124  to provide several purposes. A first lumen  118  can provide fluid to the balloon as discussed above. Second and third lumens  120 ,  122  can house pull wires to deflect the balloon  162  away from the longitudinal axis L-L defined by the shaft  130 . A fourth lumen  124  can provide a path for wires and cables such as the TAS wire  114 , wires to ablation and/or mapping electrodes, etc. The shaft  130  can be modified to include fewer or additional lumens to accommodate alternative structures and functionality as understood by a person skilled in the pertinent art. 
       FIGS. 4A and 4B  illustrate the catheter  100  including an optional outer membrane  128 .  FIG. 4B  is an exploded view of  FIG. 4A . Electrodes (not illustrated) can be mounted over the balloon membrane  162 , and wires (not illustrated) to the electrodes can be positioned between the balloon membrane  162  and outer membrane  128  similar to configurations of corresponding structures in U.S. 2020/0155266. The catheter  100  can further include a third membrane configured similarly to corresponding structures in U.S. 2020/0155266. 
     The catheter  100  can include a navigation sensor  132  positioned in the shaft  130 , for instance in the fourth lumen  124  ( FIG. 3 ). The catheter  100  can include an inner ring  110  coupling the central tube  102  to the distal plug  106 . The distal end  188  of the balloon  162  can be affixed to the inner ring  110 , thereby fixing the distal end of the balloon  162  in relation to the central tube  102 . The catheter  100  can include a coupler  108  coupling the proximal end  186  of the balloon  162  to the shaft  130 . 
     The catheter  100  can include a fluid impermeable coupler or seal  134  between the central tube  102  and the shaft  130  so that the fluid impermeable seal  134  is over the central tube and within the shaft. As illustrated, the seal  134  couples the central tube  102  to the inflation tube  116 . Alternatively, the shaft  130  can include an inflation lumen sealed to the seal  134  (or similar seal  134  with appropriate configuration) to the central tube  102  so that the inflatable balloon  162  can be inflated directly through the inflation lumen without requiring the inflation tube  116 . 
       FIGS. 5A and 5B  illustrate an alternative catheter  200  having an irrigation balloon  264  over an inflation balloon  262  and a central tube  202  providing structural support for the balloons  262 ,  264  and a flow path to inflate the inflation balloon  262 . The central tube includes inflation ports  204 . The central tube  202  can be configured to inflate and/or deflate the inflation balloon  262  similarly to the central tube  102  illustrated in  FIGS. 1A through 4B . The central tube  102  can slide longitudinally in relation to a shaft  230  to adjust a longitudinal dimension, height H 1 , H 3  of the balloons  262 ,  264 . The central tube  202  can be obstructed by a distal plug  106  ( FIGS. 1A through 4D ) or other obstruction to inhibit fluid from exiting the distal end  226  of the catheter  200 . 
     The irrigation balloon  264  and inner inflation balloon  262  are affixed to each other at a distal balloon end  288  and a proximal balloon end  286  fixed in relation to a catheter shaft  230 . An irrigation lumen  266  provides a conduit for irrigation fluid to the irrigation balloon  264 . The irrigation balloon  264  includes pores  272  sized and positioned to allow irrigation fluid to exit the interior of the irrigation balloon  264 . The non-irrigating inner inflation balloon  262  is impermeable to the irrigation fluid such that no significant amount of irrigation fluid passes from the outer balloon  264  into the inner balloon  262  when negative pressure is applied to deflate the inner balloon  262 , meaning any amount of irrigation fluid that may enter the inner balloon  262  during deflation does not significantly affect the resulting volume of the inner balloon  262 . 
     An inflation lumen  216  is fluidically coupled to the central tube  202 . The irrigation lumen  266  and inflation lumen  216  are positioned in the shaft  230 . The shaft  230 , irrigation lumen  266 , and inflation lumen  216  can have sufficient length to extend from the treatment site, through vasculature, and outside the patient. The distal portion of the catheter  200  can be placed by manipulation of a proximal portion of the shaft  230 . Fluids can be injected into respective proximal openings of the irrigation lumen  266  and inflation lumen  268 . The catheter  200  can include an inflation tube similar to the inflation tube  116  illustrated in  FIG. 4D . The catheter  200  can include a seal between the central tube  202  and shaft  230  to the irrigation lumen  266  similar to the seal  134  illustrated in  FIG. 4D . 
     Configured as such, the volume of the inner balloon  262  can be deflated more rapidly than an equivalent volume of an irrigation balloon lacking the inner balloon structure  262 . This is because, generally, an irrigation balloon includes pores that allow backflow of fluids into the volume of the irrigation balloon when negative pressure is applied to deflate the irrigation balloon. 
     The catheter  200  can otherwise be manipulated and constructed similar to corresponding catheters in U.S. 2020/0147295. 
     The irrigation balloon  264  can expand and contract through a range of circumferences during inflation and deflation. The irrigation balloon  264  can have a small circumference C 7  when in the deflated state ( FIG. 5B ) sized so that the irrigation balloon  264  can be retracted into a sheath. The irrigation balloon  264  can have a maximum circumference C 5  when in the inflated state ( FIG. 5A ). 
     The inner balloon  262  can expand and contract through a range of circumferences during inflation and deflation. The inner balloon  262  can have a small circumference C 6  when the catheter  200  is in the deflated state ( FIG. 5B ) and a larger circumference C 4  when the catheter  200  is in an inflated state ( FIG. 5A ). The circumference C 4  of the inner inflation balloon  262  in the inflated state can be sized in relation to the circumference C 5  of the irrigation balloon  264  in the inflated state ( FIG. 5A ) to allow irrigation fluids to pass between the outer surface of the inner balloon  262  and the inner surface of the outer balloon  264  and through the pores  272  at a desired flow rate. 
     When the balloons  262 ,  264  are in the inflated state as illustrated in  FIG. 5A , the balloons can respectively have circular cross-sectional shapes in plane P. The circular cross-sectional shapes of the balloons  262 ,  264  can be concentric. The central tube  202  can be concentric with the balloons  262 ,  264  in the plane P. The balloons  262 ,  264  can be substantially spherical as illustrated in  FIG. 5A  or can form inflated shapes similar to those illustrated in  FIGS. 1A and 1B . 
     The central tube  202  can telescope to allow the irrigation balloon  264  and inner balloon  262  to contract and elongate during inflation and deflation. The balloons  262 ,  264  can have a maximum height H 3  when in the deflated state ( FIG. 5B ) and a minimum height H 1  when in the inflated state ( FIG. 5A ) similar to the example catheter  100  illustrated in  FIGS. 1A and 1C . 
       FIG. 6  is an illustration of a distal portion of another example balloon catheter  300  having an expanding set of splines  356  and a collapsing set of splines  358 . The balloon catheter  300  is illustrated in an inflated state. The catheter  300  includes a central tube  302  having inflation ports  304  configured to inflate a balloon  354  similar to the central tube  102  illustrated in  FIGS. 1A through 4B . The central tube  302  can slide longitudinally in relation to a shaft  330  to adjust a longitudinal dimension, height H 1 , H 2 , H 3  of a balloon  354  similar to as illustrated in  FIGS. 1A through 1C . The central tube  302  can be obstructed by a distal plug  106  ( FIGS. 1A through 4D ) or other obstruction to inhibit fluid from exiting the distal end of the catheter  300 . 
     The catheter  300  includes a balloon assembly  340  including the expanding set of splines  356 , the collapsing set of splines  358 , the balloon  354 , and the central tube  302 . The splines can be made at least partially from shape-memory material. The splines  356 ,  358  are preferably positioned inside the balloon  354 , although they can be positioned outside the balloon  354 . The splines  356 ,  358  can be configured to be heated using electrical current provided via suitable wires that run through the catheter&#39;s shaft  330 . A physician may operate (e.g., activate and deactivate) each of the two sets of splines  356 ,  358  independently. The splines  356 ,  358  can be configured similarly to corresponding structures in U.S. 2019/0059818. The catheter  300  can include additional compatible functionality and structures as presented in U.S. 2019/0059818. 
     The balloon  354  can be expanded by heating of the expanding set of splines  356 , and the expanding set of splines  356  can be forced to collapse upon removal of heat. The balloon  354  can be collapsed by heating the collapsing set of splines  358 , and the collapsing set of splines  358  can be forced to expand upon removal of the heat. As the balloon  354  expands and collapses, the central tube  302  can slide longitudinally in relation to the shaft to longitudinally elongate and foreshorten the balloon  354 . The splines  356 ,  358  can be affixed so that distal ends of the splines are fixed in relation to the central tube  302  and proximal ends of the splines are fixed in relation to the shaft  330 . As the balloon  354  reshapes in response to expansion and/or collapse of the splines  356 ,  358 , the central tube  302  can slide in relation to the shaft  330 . 
     The splines  356 ,  358  are distributed circumferentially around the inside of the balloon  354 . The splines  356 ,  358  may be assembled in an alternating fashion, e.g., expanding splines  356  placed between two collapsing splines  358 , and vice versa. This configuration balances the splines  356  that expand the balloon  354  the splines  358  that collapse and have it back mechanically ready to be easily pulled back into a sheath. 
     The balloon assembly  340  can include a suitable number of splines, in various suitable arrangements. For example, the number of expanding splines  356  can be different than the number of collapsing splines  358 . The balloon assembly  340  can include one or more additional splines that are not made of a shape-memory material. More than two sets of splines can be used. In some examples, the expanding set of splines  356  can be omitted, and pressure from inflation fluid within the balloon  354  can be sufficient to expand the balloon  354 . The collapsing set of splines  358  can be activated to collapse the balloon  354  for re-sheathing. 
       FIGS. 7A and 7B  are illustrations of a distal portion of another example irrigation balloon catheter  400  having a self-expandable spring  451 .  FIG. 7A  illustrates the distal portion in a radially contracted, longitudinally extended state.  FIG. 7B  illustrates the distal portion in a radially expanded, longitudinally retracted state. The catheter  400  includes a central tube  402  having inflation ports  404  configured to inflate a balloon  462  similar to the central tube  102  illustrated in  FIGS. 1A through 4B . The central tube  402  can slide longitudinally in relation to a shaft  430  to adjust a longitudinal dimension, height H 1 , H 2 , H 3  of a balloon  462  similar to as illustrated in  FIGS. 1A through 1C . The central tube  402  can be obstructed by a distal plug  106  ( FIGS. 1A through 4D ) or other obstruction to inhibit fluid from exiting the distal end of the catheter  400 . 
       FIG. 7A  illustrates a telescopic balloon assembly  440  of the catheter  400  in an elongated state fitted at the distal end of a shaft  430 . A proximal section  448  and the central tube  402  are assembled into a two-part structure of the telescopic assembly  440 . The proximal section  448  is tubular and shaped to receive the central tube  402 . The proximal section  448  is coupled to the catheter shaft  430 . The central tube  402  can move telescopically inside the proximal section  448 , i.e., its motion is either proximally or distally along the longitudinal axis L-L. The balloon  462  is coupled at its distal end the central tube  402  by a distal anchor  456  and is coupled at its proximal end to the proximal section  448  by a proximal anchor  458 . 
     A puller-wire  452  runs through the shaft  430  and within the two-part telescopic assembly  440  and is connected to the central tube  402 . The puller-wire  452  can be operated (e.g., pulled or relaxed) from a handle (not illustrated). The puller-wire  452  can be pulled to cause the central tube  402  to move into the proximal section  448 , thereby foreshortening a longitudinal dimension (i.e. height) of the balloon  462  to move the telescopic assembly  440  from the longitudinally extended height illustrated in  FIG. 7A  to the longitudinally retracted state illustrated in  FIG. 7B . A stopper  459  positioned on the central tube  402  can limit the motion of central tube  402  in the proximal direction when the stopper  459  contacts the proximal section  448 . The balloon  462  can then be inflated as illustrated in  FIG. 7B . The spring  451  can provide a force to cause the telescopic assembly  440  to move from the longitudinally retracted state illustrated in  FIG. 7B  to the longitudinally extended state illustrated in  FIG. 7A  when tension on the puller-wire  452  is relaxed. 
     The catheter  400  can include an inflation tube or inflation lumen similar to the inflation tube  116  and alternative inflation lumens described in relation to the catheter  100  illustrated in  FIGS. 1A through 4B . The catheter  400  can include additional compatible functionality and structures as presented in U.S. 2019/0217065. 
       FIG. 8  is an illustration of a system  10  for diagnosis and/or treatment of a heart  12  of a living patient  36 . One commercial product embodying elements of system  10  is available as the CARTO® 3 System, available from Biosense Webster, Inc. located in California, U.S.A. 
     A balloon catheter  14  can be constructed and function similar to example catheters  100 ,  200 ,  300 ,  400  illustrated and described herein including those described in references incorporated by reference herein, variations thereof, and alternatives thereto as understood by a person skilled in the pertinent art according to the teachings herein. The balloon catheter  14  can further include compatible features of the various catheters  100 ,  200 ,  300 ,  400  illustrated and described herein including those described in the references incorporated by reference herein. 
     The balloon catheter  14  can be percutaneously inserted by an operator  16  through the patient&#39;s vascular system and a shaft  30  of the catheter  14  can be manipulated to position a balloon  2  near a distal end of the balloon catheter  14  in a chamber or vascular structure of the heart  12 . The operator  16 , who is typically a physician, can inflate the balloon  2  and bring electrodes  42  on the balloon surface into contact with the heart wall, for example, at an ablation target site. The balloon can irrigate through pores  72 . The balloon  2  can be configured to inflate via a central tube configured similarly to any of the central tubes  102 ,  202 ,  302 ,  402  illustrated herein, variations thereof, and alternatives thereto as understood by a person skilled in the pertinent art according to the teachings herein. The central tube can telescope to allow the height of the balloon  2  to foreshorten as the balloon  2  is inflated and/or elongate as the balloon  2  is deflated. 
     Electrical signals measured by the electrodes  42  can be used to prepare electrical activation maps. Electrical activation maps can be prepared, according to methods disclosed in U.S. Pat. Nos. 6,226,542, 6,301,496, and 6,892,091, each incorporated herein by reference. 
     Areas determined to be abnormal, for example by evaluation of the electrical activation maps, can be ablated by application of thermal energy, e.g., by passage of radiofrequency electrical current through wires in the balloon catheter  14  to one or more electrodes  42  positioned on the balloon  2 , which apply the radiofrequency energy to target tissue. The electrodes  42  can be used both for measure electrical signals and apply radiofrequency ablation; alternatively, each process can be performed by different electrodes, potentially on different catheters. 
     During ablation, energy from the electrical current (alternating in the form of radiofrequency or direct current in bipolar pulse) is absorbed in the tissue, to cause a permanent loss of its electrical excitability. This procedure is typically intended to create non-conducting lesions in the cardiac tissue, which disrupt the abnormal electrical pathway causing the arrhythmia. Such principles can be applied to different heart chambers to diagnose and treat many different types of cardiac arrhythmias. 
     The catheter  14  can include a handle  20 , having suitable controls on the handle to enable the operator  16  to steer, position and orient the distal end of the catheter as desired for ablation and/or diagnosis. To aid the operator  16 , the balloon catheter  14  can include position sensors positioned near the distal end of the balloon catheter  14  (e.g. under or near to the balloon  2 ) that provide signals to a processor  22 , located in a console  24 . The console  24  can include memory  58  in communication with the processor  22  that when executed by the processor  22  cause the console  24  to perform various functions during treatment. The console  24  can further include an ablation module  74 , irrigation module  76 , and inflation module  78  that can each respectively include hardware and software (e.g. in memory  58 ) to execute various functions related to the respective module. The modules  74 ,  76 ,  78  can include common hardware and/or software and are included to illustrate various functionality of the console  24 . The console  24  can include additional modules not illustrated. The irrigation module  76  and inflation module  78  can be one in the same or separate (e.g. when the catheter  14  includes separate irrigation and inflation balloons). 
     Ablation energy and electrical signals can be conveyed to and from the heart  12  through the electrodes  42  on the balloon  2  via a cable  38  to the console  24 . Pacing signals and other control signals may be conveyed from the console  24  through the cable  38  and the electrodes  42  to the heart  12 . This functionality can be controlled by the ablation module  74 . 
     Wire connections  35  link the console  24  with body surface electrodes  40  and other components of a positioning sub-system for measuring location and orientation coordinates of the catheter  14 . The processor  22  or another processor may be an element of the positioning subsystem. The electrodes  42  on the balloon  2  and the body surface electrodes  40  may be used to measure tissue impedance at the ablation site as taught in U.S. Pat. No. 7,536,218, incorporated herein by reference. 
     A temperature sensor, typically a thermocouple or thermistor, may be mounted on or near each of the electrodes  42 . An example of the temperature sensor as used in conjunction with the ablation electrode is shown and described in U.S. Patent Publication 2019/0298441 incorporated herein by reference. 
     The catheter  14  can include a force sensor configured to provide a signal indicative of a magnitude and direction of force applied by a balloon on tissue such as described in U.S. patent application Ser. No. 16/863,815 filed Apr. 30, 2020, titled “Balloon Catheter with Force Sensor” with attorney docket number B106131USNP1, incorporated by reference herein. 
     The console  24  can include one or more ablation power generators  25  included in, or at least controlled by the ablation module  74 . The catheter  14  can be configured to conduct ablative energy to the heart using any known ablation energies or modalities, e.g., radiofrequency energy, electroporation, ultrasound energy, cryogenic energy, and laser-produced light energy. Such methods are disclosed in commonly assigned U.S. Pat. Nos. 6,814,733, 6,997,924, and 7,156,816, and “Theoretical Considerations of Tissue Electroporation With High-Frequency Bipolar Pulses” by Christopher B. Arena, Michael B. Sano, Marissa Nichole Rylander, and Rafael V. Davalos (May 2011), and “Ablative therapies: Advantages and disadvantages of radiofrequency, cryotherapy, microwave and electroporation methods, or how to choose the right method for an individual patient?” by O. Seror (April 2015), each incorporated herein by reference. 
     The positioning subsystem can include a magnetic position tracking arrangement that determines the position and orientation of the catheter  14  by generating magnetic fields, using magnetic field generators  28 , in a predefined working volume and sensing these fields at the catheter, using coils or traces disposed within the catheter, typically proximate to the tip. A positioning subsystem is described in U.S. Pat. Nos. 7,756,576 and 7,536,218, each incorporated herein in their entireties. 
     The operator  16  may observe and regulate the functions of the catheter  14  via the console  24 . The processor  22  can drive a display  29 . The processor  22  and associated circuitry of the console  24  can be configured to receive, amplify, filter and digitize signals from the catheter  14 , including signals generated by sensors such as electrical, temperature and contact force sensors, and a plurality of location sensing coils or traces located distally in the catheter  14 . The digitized signals are received and used by the console  24  and the positioning subsystem to compute the position and orientation of the catheter  14 , and to analyze the electrical signals from the electrodes and sensors. 
     In order to generate electroanatomic maps, the processor  22  can include an electroanatomic map generator, an image registration program, an image or data analysis program and a graphical user interface configured to present graphical information on the display  29 . 
     The system  10  can include other elements, which are not shown in the figures for the sake of simplicity. For example, the system  10  can include an electrocardiogram (ECG) monitor, coupled to receive signals from one or more body surface electrodes, in order to provide an ECG synchronization signal to the console  24 . The system  10  can include a reference position sensor, either on an externally applied reference patch attached to the exterior of the subject&#39;s body, or on an internally placed catheter, which is inserted into the heart  12  maintained in a fixed position relative to the heart  12 . The system  10  can further include pumps and lines for circulating liquids through the catheter  14  for irrigating the treatment site. The system  10  can be configured to receive image data from an external imaging modality, such as an MRI unit, CT, or the like and includes image processors that can be incorporated in or invoked by the processor  22  for generating and displaying images.