Patent Publication Number: US-2023146949-A1

Title: Medical occluder delivery systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present patent application claims priority from U.S. Provisional Application 62/994,465, filed Mar. 25, 2020, which is assigned to the assignee of the present application and incorporated herein by reference. 
    
    
     FIELD OF THE APPLICATION 
     The present application relates generally to medical device systems and methods, that employ a catheter delivery systems or other device and liquid inflation lumens. 
     BACKGROUND OF THE APPLICATION 
     There are several types of pathologic passageways within the body. If located in blood vessels or in the heart, such passageways can cause alteration of blood flow. Paravalvular leak is a common complication of patients undergoing implantation of either surgical or transcatheter prostheses. The left atrial appendage (LAA) is a cavity that presents in the left atrium of the heart. In patients with atrial fibrillation the passage and steadiness of blood within this cavity can cause thrombus formation, which increase the risk of stroke. The option to treat these defects percutaneously may offers safer solution for high-risk patients, without exposing them to risk related to open heart reoperation. New concepts and implementations of occlusion devices based on detachable balloon implants are being developed, which are specifically designed for paravalvular leak occlusion, LAA occlusion or other irregular cardiovascular defects target sites. 
     The delivery of these new occlusion devices requires transcatheter methods and techniques using elongated catheter tools to target and position the devices at the desired implantation area in the subject&#39;s body. 
     The delivery of a balloon-based implant to a desired target site requires the performance of several steps, including navigation, trajectory, inflation, deflation, activation, dislocation, deployment and retrieval of the implant. Various systems have been developed for the delivery of balloon implants to a desired target site, which may be able to perform some or all of these required steps, usually by mean of handle controls, knobs or manipulation during the procedure by the operator. Some of these steps should be performed in combination among them, for a proper implant deployment, but the activation of them by the operator is sometimes not reliable, stable and efficient. 
     SUMMARY OF THE APPLICATION 
     Some embodiments of the present invention provide a delivery system for controlling the inflation, deflation, activation and deployment of a detachable balloon-based implant in medical procedures involving blood vessels, body cavities, cardiovascular defects occlusion, treatment of left atrial appendage, and the like. 
     In some applications of the present invention, a delivery system is provided for the control and deployment of a cardiovascular device, for occluding a cardiovascular defect or a gap between a medical device and adjacent body tissue. The delivery system is for use with a guidewire and a balloon-based occlusion device. The delivery system enables over-the-wire engagement of the cardiovascular defect, the adjustment of the length and orientation of the occlusion devices during deployment, and the inflation of the balloon chamber with saline or another filling fluid. The delivery system automates the balloon-based implant inflation and its shortening to the deployment configuration 
     The delivery system comprises a fluid-retaining chamber, which is delimited by a tubular barrel having a proximal end, a distal end, and an internal surface. A plunger is slidingly disposed in the fluid-retaining chamber, as a movable membrane to draw fluid into the fluid-retaining chamber and expel fluid out of the fluid-retaining chamber, thereby filling and unfilling the fluid-retaining chamber, respectively. The fluid-retaining chamber includes a port at a distal end of the fluid-retaining chamber. The port is optionally connected to a cannular extension tube which is in fluid flow communication with the fluid-retaining chamber. The cannular extension may be used during or after the activation of the plunger into the fluid-retaining chamber to insert additional fluid into the fluid-retaining chamber and consequently into the balloon-based implant. The fluid-retaining chamber is configured to expel fluid to an catheter fluid-conveyance lumen connected proximally to the fluid-retaining chamber and distally coupled to the balloon-based implant. The expulsion of fluid from the fluid-retaining chamber inflates a balloon of the balloon-based implant during its deployment. 
     For some applications, the delivery system further comprises an actuator disposed longitudinally slidable in a delivery handle, in series to the fluid-retaining chamber, connected to a catheter lumen shaft which is in direct connection with the balloon-based implant throughout all the handle components and the catheter shaft which is connected to the implant. The actuator is longitudinally movable with respect to the delivery handle components so as to shorten or elongate a length of the implant. 
     For some applications, the delivery handle further comprises a double-threaded tube which connects and couples the actuation of the plunger into the fluid-retaining chamber and the longitudinal sliding of the actuator, automating the expulsion of fluid from the fluid-retaining chamber into the balloon-based implant, the withdrawing of fluid into the fluid-retaining chamber from the balloon-based implant, and the concurrent shortening or elongation, respectively, of the implant length. The double-threaded tube is activated by the rotation of a proximal rotatable user-control knob of the delivery handle. 
     In some applications of the present invention, the delivery handle further comprises a fluid-retaining chamber sliding mechanism which allows the movement of the fluid-retaining chamber over the plunger independently from the double-threaded tube. The fluid sliding chamber is actuated by a proximal rotatable user-control knob positioned the delivery handle. 
     In some applications of the present invention, the delivery handle further comprises a locking toggle mechanism which limits the movement of the double-threaded tube within a pre-fixed motion range. The locking toggle mechanism, when released, allows the prosecution of double-threaded tube movement until its full range of motion. The locking toggle mechanism is activated by a mechanical motion of a toggling button positioned on the delivery handle. 
     The delivery system thus provides for more reliable, stable, efficient, and simple delivery of inflatable balloon-based implants, automating some or all of the deployment steps performed manually in conventional deployment systems. The delivery system thus may reduce occurrence of misuse and other operator related implantation errors, and may reduce the overall procedure time required, and therefore reduce patient discomfort and improve precision and procedural outcomes. The delivery system may also reduce the amount of effort required by the physician prior to and during use of the system, as well as ensure that the balloon-based implant is properly implanted and maneuvered during insertion into the target tissue, during inflation of the balloon of the balloon-based implant, and during its deployment. 
     The device may further comprise a guidewire/infusion lumen disposed parallel to the catheter fluid-conveyance lumen, such as within catheter fluid-conveyance lumen. The guidewire/infusion lumen is also in fluid communication with the internal channel of the inflatable balloon, and may be used for wires, guidewires or fluid agent passage from the proximal end of the delivery handle, to the distal end of the balloon-based implant. The guidewire may be placed at the beginning of the delivery procedure, to guide the catheter to the target area. The agent delivered through this guidewire/infusion lumen may be used for fluoroscopic contrast fluid injection to the distal outlet of the balloon-based implant, outside of the balloon-based implant, as the balloon inflates. Such a configuration may be advantageous to evaluate the adherence of the balloon-based implant to the surrounding target anatomy, in order for the operator to evaluate if to further inflate the balloon-based implant in order to achieve complete adherence to the anatomy. A syringe may be used for the agent insertion into this guidewire/infusion lumen. 
     The delivery system may further comprise a micro-pump in fluid communication with the extension cannula to provide controlled balloon inflation without shortening of the implant. Alternatively, the micro-pump may be in communication with the fluid-retaining chamber, in order to activate the sliding movement of the chamber plunger and the activation of the coupled thread mechanism; such a configuration may be desirable to provide consistency in dose rates, amounts, and pressures, as well in device shortening, with limited operator interaction. 
     In another application of the present invention, a method is provided for inflating a balloon-based implant using blood from the patient during an implantation procedure, which is collected distally within the catheter and proximally to the implant. 
     The catheter system is provided with a delivery catheter connected to the balloon-based implant. The delivery catheter is shaped so as to define a fluid-retaining chamber within its lumen. A fluid passage hole is configured within this fluid-retaining chamber, passing through the shaft and in direct communication with the blood stream. A plunger is disposed within this fluid-retaining chamber, able to slide longitudinally using a delivery handle. Retracting the plunger proximally draws blood into this fluid-retaining chamber. Once the fluid-retaining chamber is full with the patient blood, the fluid-retaining chamber is circumferentially rotated to align its fluid passage hole to the connecting entrance of the fluid inflation catheter within the shaft, which is connected to the balloon-based implant. Once the fluid communication between the fluid-retaining chamber and the inflation catheter is completed, the plunger may be distally moved to provide inflation to the balloon-based implant. 
     These steps are reversible and may be used for deflating the balloon-based implant. These steps may be performed also more than once in series, to provide more inflation volume to the balloon-based implant. 
     This other application of the present invention may be combined with the other applications of the present invention described above. 
     There is therefore provided, in accordance with an application of the present invention, a delivery system for delivering and deploying an implantable balloon-based occlusion device that includes an inflatable balloon, the delivery system including: 
     a fluid-retaining chamber, delimited by a tubular barrel having a proximal end, a distal end, and an internal surface; 
     a plunger, which is slidingly disposed in the fluid-retaining chamber so as to provide a movable membrane configured to draw fluid into the fluid-retaining chamber and expel the fluid from the fluid-retaining chamber, thereby filling and unfilling the fluid-retaining chamber, respectively; 
     a delivery handle, which includes a proximal rotatable user-control knob; 
     a fluid-conveyance lumen catheter, which is shaped so as to define a catheter fluid-conveyance lumen in fluid communication (a) with the fluid-retaining chamber and (b) with the inflatable balloon of the balloon-based occlusion device when the fluid-conveyance lumen catheter is coupled to the inflatable balloon; 
     a catheter lumen shaft, which is in direct reversible connection with the balloon-based occlusion device, longitudinally slidable with respect to the delivery handle to set a shortening or elongation of a longitudinal dimension of the balloon-based occlusion device; 
     an actuator, connected to the catheter lumen shaft; and 
     a double-threaded tube, which is connected to the proximal rotatable user-control knob, and which connects and couples actuation of the plunger into the fluid-retaining chamber and longitudinal sliding of the actuator, such that rotation of the proximal rotatable user-control knob:
         in a first rotational direction, activates the double-threaded tube to concurrently (a) expel at least some of the fluid from the fluid-retaining chamber into the inflatable balloon of the balloon-based occlusion device, via the catheter fluid-conveyance lumen, and (b) shorten a length of the balloon-based occlusion device by proximally moving the actuator, which in turn proximally pulls the catheter lumen shaft, and   in a second rotational direction opposite the first rotational direction, activates the double-threaded tube to concurrently (a) withdraw at least some of the fluid into the fluid-retaining chamber from the inflatable balloon of the balloon-based occlusion device, via the catheter fluid-conveyance lumen, and (b) elongate the length of the balloon-based occlusion device by distally moving the actuator, which in turn distally pushes the catheter lumen shaft.       

     For some applications, the catheter lumen shaft is disposed within the catheter fluid-conveyance lumen of the fluid-conveyance lumen catheter. 
     For some applications, the fluid-retaining chamber is disposed within the delivery handle. 
     For some applications, the delivery handle includes a delivery-handle fluid-conveyance lumen tube, which is shaped so as to define a delivery-handle fluid-conveyance lumen in fluid communication with the fluid-retaining chamber and the catheter fluid-conveyance lumen. 
     For some applications, the delivery handle includes a delivery-handle lumen shaft, which is disposed within the delivery-handle fluid-conveyance lumen, and which extends from the catheter lumen shaft and longitudinally slidable with respect to the delivery handle. 
     For some applications, the delivery handle further includes a distal user control, which is configured to release the balloon-based implant from the delivery system. 
     For some applications, the delivery handle includes a window opening, and an external surface of the fluid-retaining chamber is marked with a scale that is visible through the window opening, to enable a user to monitor an amount of the fluid present within the fluid-retaining chamber. 
     For some applications, the apparatus further includes a cannula extension, which is connected at one end of the cannula extension in fluid communication with the fluid-retaining chamber. 
     For some applications, the delivery handle further includes a plunger pusher, and the double-threaded tube is shaped so as to define: a first thread that is threadedly coupled to a corresponding second thread defined by the plunger pusher, and a third thread that is threadedly coupled to a corresponding fourth thread defined by the actuator. 
     For some applications: 
     the delivery handle includes a safety latch, which is configured to assume locked and unlocked states, 
     the safety latch, when in the locked state, blocks the double-threaded tube from completion of concurrently (a) expelling at least some of the fluid from the fluid-retaining chamber into the inflatable balloon and (b) shortening the length of the balloon-based implant, and 
     the safety latch, when in the unlocked state, allows further rotation of the proximal rotatable user-control knob in the first rotation direction to complete concurrently (a) expelling at least some of the fluid from the fluid-retaining chamber into the inflatable balloon and (b) shortening the length of the balloon-based implant. 
     For some applications, the delivery handle further includes a length-maintaining fluid user-control knob, and the delivery handle is configured such that rotation of the length-maintaining fluid user-control knob, in a first rotational direction, proximally moves the fluid-retaining chamber within the delivery handle while the plunger remains longitudinally stationary, thereby expelling additional fluid from the fluid-retaining chamber into the balloon of the balloon-based implant without changing the length of the balloon-based occlusion device. 
     For some applications, the delivery system further includes a delivery catheter that includes the fluid-conveyance lumen catheter and the catheter lumen shaft, and the fluid-retaining chamber is disposed within the delivery catheter, in a proximal or distal position along the delivery catheter. For some applications, the fluid-retaining chamber is shaped so as to define two sub-chambers, having a shaft opening allowing the collection of blood from the patient circulatory system into the fluid-retaining chamber, and the injection of the collected blood into the balloon-based occlusion device. 
     For some applications, an occlusion system is provided that includes the delivery system and further includes the balloon-based occlusion device. For some applications, the balloon-based occlusion device includes an actuating shaft, which is (a) disposed at least partially within the balloon, (b) connected to a distal end portion of the balloon, and (c) longitudinally moveable with respect to a proximal end portion of the balloon so as to set a distance between the distal and the proximal end portions of the balloon. For some applications, the balloon-based occlusion device further includes a locking mechanism, which is configured to assume locked and unlocked states, and which is configured, when in the locked state, to maintain, between the distal end portion of the balloon and the proximal end portion of the balloon, the distance set using the actuating shaft. 
     There is further provided, in accordance with an application of the present invention, a delivery system for delivering and deploying an implantable balloon-based occlusion device that includes an inflatable balloon, the delivery system including: 
     a delivery handle, which includes:
         a fluid-retaining chamber, delimited by a tubular barrel having a proximal end, a distal end, and an internal surface;   a plunger, which is slidingly disposed in the fluid-retaining chamber so as to provide a movable membrane; and   a proximal rotatable user-control knob;       

     a fluid-conveyance lumen catheter, which is shaped so as to define a catheter fluid-conveyance lumen in fluid communication (a) with the fluid-retaining chamber and (b) with the inflatable balloon of the balloon-based occlusion device when the fluid-conveyance lumen catheter is coupled to the inflatable balloon; and 
     a catheter lumen shaft, which is in reversible connection with the balloon-based occlusion device, longitudinally slidable with respect to the delivery handle, 
     wherein the delivery handle is configured such that rotation of the proximal rotatable user-control knob in a first rotational direction concurrently (a) expels at least some of the fluid from the fluid-retaining chamber into the inflatable balloon of the balloon-based occlusion device, via the catheter fluid-conveyance lumen, and (b) shortens a length of the balloon-based occlusion device by proximally pulling the catheter lumen shaft. 
     For some applications, the delivery handle is configured such that rotation of the proximal rotatable user-control knob in a second rotational direction opposite the first rotational direction concurrently (a) withdraws at least some of the fluid into the fluid-retaining chamber from the inflatable balloon of the balloon-based occlusion device, via the catheter fluid-conveyance lumen, and (b) elongates the length of the balloon-based occlusion device by distally pushing the catheter lumen shaft. 
     For some applications, the catheter lumen shaft is disposed within the catheter fluid-conveyance lumen. 
     For some applications, the fluid-retaining chamber is disposed within the delivery handle. 
     For some applications, the delivery handle further includes a distal user control, which is configured to release the balloon-based implant from the delivery system. 
     For some applications, the delivery handle includes a window opening, and an external surface of the fluid-retaining chamber is marked with a scale that is visible through the window opening, to enable a user to monitor an amount of the fluid present within the fluid-retaining chamber. 
     For some applications, the delivery handle includes a delivery-handle fluid-conveyance lumen tube, which is shaped so as to define a delivery-handle fluid-conveyance lumen in fluid communication with the fluid-retaining chamber and the catheter fluid-conveyance lumen. 
     For some applications, the delivery handle includes a delivery-handle lumen shaft, which is disposed within the delivery-handle fluid-conveyance lumen, and which extends from the catheter lumen shaft and longitudinally slidable with respect to the delivery handle. 
     For some applications, the apparatus further includes a cannula extension, which is connected at one end of the cannula extension in fluid communication with the fluid-retaining chamber. 
     For some applications, the delivery handle further includes a length-maintaining fluid user-control knob, and the delivery handle is configured such that rotation of the length-maintaining fluid user-control knob, in a first rotational direction, proximally moves the fluid-retaining chamber within the delivery handle while the plunger remains longitudinally stationary, thereby expelling additional fluid from the fluid-retaining chamber into the balloon of the balloon-based implant without changing the length of the balloon-based occlusion device. 
     For some applications, the delivery handle further includes a double-threaded tube, which is connected to the proximal rotatable user-control knob, and which connects and couples actuation of the plunger into the fluid-retaining chamber and longitudinal sliding of the catheter lumen shaft. 
     For some applications: 
     the delivery handle further includes an actuator, connected to the catheter lumen shaft, and 
     the delivery handle is configured such that rotation of the proximal rotatable user-control knob in the first rotational direction activates the double-threaded tube to concurrently (a) expel at least some of the fluid from the fluid-retaining chamber into the inflatable balloon of the balloon-based occlusion device, via the catheter fluid-conveyance lumen, and (b) shorten the length of the balloon-based occlusion device by proximally moving the actuator, which in turn proximally pulls the catheter lumen shaft 
     For some applications, the delivery handle is configured such that rotation of the proximal rotatable user-control knob in a second rotational direction opposite the first rotational direction, activates the double-threaded tube to concurrently (a) withdraw at least some of the fluid into the fluid-retaining chamber from the inflatable balloon of the balloon-based occlusion device, via the catheter fluid-conveyance lumen, and (b) elongate the length of the balloon-based occlusion device by distally moving the actuator, which in turn distally pushes the catheter lumen shaft. 
     For some applications, the delivery handle further includes a plunger pusher and an actuator connected to the catheter lumen shaft, and the double-threaded tube is shaped so as to define: a first thread that is threadedly coupled to a corresponding second thread defined by the plunger pusher, and a third thread that is threadedly coupled to a corresponding fourth thread defined by the actuator. 
     For some applications: 
     the delivery handle includes a safety latch, which is configured to assume locked and unlocked states, 
     the safety latch, when in the locked state, blocks the double-threaded tube from completion of concurrently (a) expelling at least some of the fluid from the fluid-retaining chamber into the inflatable balloon and (b) shortening the length of the balloon-based implant, and 
     the safety latch, when in the unlocked state, allows further rotation of the proximal rotatable user-control knob in the first rotation direction to complete concurrently (a) expelling at least some of the fluid from the fluid-retaining chamber into the inflatable balloon and (b) shortening the length of the balloon-based implant. 
     For some applications, an occlusion system is provided that includes the delivery system and further includes the balloon-based occlusion device. For some applications, the balloon-based occlusion device includes an actuating shaft, which is (a) disposed at least partially within the balloon, (b) connected to a distal end portion of the balloon, and (c) longitudinally moveable with respect to a proximal end portion of the balloon so as to set a distance between the distal and the proximal end portions of the balloon. For some applications, the balloon-based occlusion device further includes a locking mechanism, which is configured to assume locked and unlocked states, and which is configured, when in the locked state, to maintain, between the distal end portion of the balloon and the proximal end portion of the balloon, the distance set using the actuating shaft. 
     There is still further provided, in accordance with an application of the present invention, a method for delivering and deploying an implantable balloon-based occlusion device that includes an inflatable balloon, the method including, using a delivery system: 
     filling, with fluid, a fluid-retaining chamber of the delivery system, the fluid-retaining chamber delimited by a tubular barrel having a proximal end, a distal end, and an internal surface, wherein a plunger is slidingly disposed in the fluid-retaining chamber so as to provide a movable membrane; 
     using a delivery catheter of the delivery system, advancing the implantable balloon-based occlusion device to a desired site in a body of a subject, the delivery catheter including (i) a fluid-conveyance lumen catheter, which is shaped so as to define a catheter fluid-conveyance lumen in fluid communication (a) with the fluid-retaining chamber and (b) with the inflatable balloon of the balloon-based occlusion device when the fluid-conveyance lumen catheter is coupled to the inflatable balloon, and (ii) a catheter lumen shaft, which is in reversible connection with the balloon-based occlusion device, longitudinally slidable with respect to the delivery handle; and 
     thereafter, rotating a proximal rotatable user-control knob of a delivery handle of the delivery system in a first rotation direction, such that that the delivery system concurrently (a) expels at least some of the fluid from the fluid-retaining chamber into the inflatable balloon of the balloon-based occlusion device, via the catheter fluid-conveyance lumen, and (b) shortens a length of the balloon-based occlusion device by proximally pulling the catheter lumen shaft. 
     For some applications, the method further includes, after rotating the proximal rotatable user-control knob in the first rotation direction, rotating the proximal rotatable user-control knob in a second rotational direction opposite the first rotational direction, such that the delivery system concurrently (a) withdraws at least some of the fluid into the fluid-retaining chamber from the inflatable balloon of the balloon-based occlusion device, via the catheter fluid-conveyance lumen, and (b) elongates the length of the balloon-based occlusion device by distally pushing the catheter lumen shaft. 
     For some applications, rotating the proximal rotatable user-control knob in the first rotation direction rotates a double-threaded tube of the delivery handle. 
     For some applications: 
     the delivery handle includes a safety latch, which is configured to assume locked and unlocked states, and 
     rotating the proximal rotatable user-control knob in the first rotation direction includes, while the safety latch is in the locked state, rotating the proximal rotatable user-control knob in the first rotation direction until the safety latch blocks the delivery system from completion of concurrently (a) expelling at least some of the fluid from the fluid-retaining chamber into the inflatable balloon and (b) shortening the length of the balloon-based implant. 
     For some applications, the method further includes, after rotating the proximal rotatable user-control knob in the first rotation direction until the safety latch blocks the delivery system from the completion: 
     assessing whether the balloon-based occlusion device is properly deployed; and 
     upon assessing that balloon-based occlusion device is properly deployed, transitioning the safety latch to the unlocked state, and further rotating the proximal rotatable user-control knob in the first rotation direction to complete concurrently (a) expelling at least some of the fluid from the fluid-retaining chamber into the inflatable balloon and (b) shortening the length of the balloon-based implant. 
     For some applications, the method further includes, after rotating the proximal rotatable user-control knob in the first rotation direction until the safety latch blocks the delivery system from the completion: 
     assessing whether the balloon-based occlusion device is properly deployed; and 
     upon assessing that balloon-based occlusion device has a desired length and the balloon of the balloon-based occlusion device does not contain a desired amount fluid, adjusting an amount of the fluid in the balloon of the balloon-based occlusion device by rotating a length-maintaining fluid user-control knob of the delivery handle to move the fluid-retaining chamber within the delivery handle while the plunger remains longitudinally stationary, thereby adjusting the amount of the fluid in the balloon of the balloon-based implant without changing the length of the balloon-based occlusion device. 
     For some applications, the method further includes using a distal user control of the delivery handle to release the balloon-based implant from the delivery system. 
     For some applications, filling the fluid-retaining chamber includes filling the fluid-retaining chamber from a fluid source external to the delivery system, via a cannula extension, which is connected at one end of the cannula extension in fluid communication with the fluid-retaining chamber. 
     The present invention will be more fully understood from the following detailed description of embodiments thereof, taken together with the drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic illustration of a delivery system connected to an implantable balloon-based implant that is in a noninflated and non-deployed configuration, in accordance with an application of the present invention; 
         FIGS.  2 A-H  are schematic illustrations of a method of using the delivery system of  FIG.  1    for delivering and deploying the balloon-based implant, in accordance with an application of the present invention; 
         FIG.  3    is a schematic illustration of another delivery system connected to an implantable balloon-based implant that is in a noninflated and non-deployed configuration, in accordance with an application of the present invention; 
         FIGS.  4 A-F  are schematic illustrations of a method of using the delivery system of  FIG.  3    for delivering and deploying the balloon-based implant, in accordance with an application of the present invention; 
         FIGS.  5 A-F  are schematic illustrations of a delivery catheter, in accordance with an application of the present invention; 
         FIG.  6    is a schematic illustration of an occlusion device for occluding a left atrial appendage (LAA), in accordance with an application of the present invention; 
         FIGS.  7 A-B  are schematic cross-sectional illustrations of the occlusion device of  FIG.  6    and a distal portion of a delivery system, in accordance with an application of the present invention; 
         FIGS.  8 A-F  are schematic illustrations of steps of a method of deploying the occlusion device of  FIG.  6    using the delivery system of  FIGS.  7 A-B , in accordance with an application of the present invention; 
         FIGS.  9 A-C  are schematic cross-sectional views of a portion of the steps of the method shown in  FIGS.  8 A-F , in accordance with an application of the present invention; and 
         FIG.  10    is a schematic illustration of the occlusion device of  FIG.  6    implanted to occlude an LAA, in accordance with an application of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF APPLICATIONS 
       FIG.  1    is a schematic illustration of a delivery system  10  connected to an implantable balloon-based implant  20  that is in a noninflated and non-deployed configuration  24 , in accordance with an application of the present invention. Implantable balloon-based implant  20  includes an inflatable balloon  22 . Implantable balloon-based implant  20  is not an element of delivery system  10 . Delivery system  10  and the other delivery systems described herein are typically transcatheter delivery systems that enable percutaneous deployment of balloon-based implant  20 . 
     Reference is also made to  FIGS.  2 A-H , which are schematic illustrations of a method of using delivery system  10  for delivering and deploying balloon-based implant  20 , in accordance with an application of the present invention.  FIGS.  2 A-D  show implantable balloon-based implant  20  in noninflated and non-deployed configuration  24 , and  FIGS.  2 E-H  show implantable balloon-based implant  20  in a fully-inflated and shortened deployed configuration  25 . 
     For some applications, balloon-based implant  20  is a balloon-based occlusion device. For example, the balloon-based occlusion device may comprise a proximal LAA-orifice cover  21  and inflatable balloon  22 , surrounded by a conformable balloon frame  23 . Optionally, the balloon-based occlusion device be configured as described hereinabove with reference to  FIGS.  6 - 10    and/or may implement any of the techniques described in the patent applications incorporated hereinbelow by reference. 
     Delivery system  10  comprises a delivery handle  11  and a delivery catheter  16 . Delivery handle  11  comprises a proximal rotatable user-control knob  31  that is configured to activate a double-threaded tube  46  within handle  11 , as described hereinbelow with reference to  FIGS.  2 B-D  and  2 F-G. Optionally, delivery handle  11  further comprises a distal user control  32  that is configured to release balloon-based implant  20  from delivery system  10  (typically from delivery catheter  16 ), such as described hereinbelow with reference to  FIG.  2 H . 
     Delivery handle  11  further comprises a fluid-retaining chamber  41 , which is delimited by a tubular barrel  34  having a proximal end  36 , a distal end  38 , and an internal surface  40 . Delivery handle  11  further comprises a plunger  30  that is slidingly disposed in fluid-retaining chamber  41  so as to define a distal movable membrane  45  (i.e., a distal surface of the head of plunger  30 ) to draw fluid into fluid-retaining chamber  41  and expel fluid out of fluid-retaining chamber  41 , thereby filling and unfilling fluid-retaining chamber  41 , respectively. For example, the fluid may comprise saline. Optionally the fluid may comprise a contrast agent. 
     Optionally, an external surface of fluid-retaining chamber  41  is marked with a scale that is visible through a window opening on delivery handle  11 , to enable a user to monitor the amount of fluid present within fluid-retaining chamber  41  within delivery handle  11 . 
     As shown in  FIG.  2 C , delivery catheter  16  comprises:
         a fluid-conveyance lumen catheter  18 , which is shaped so as to define a catheter fluid-conveyance lumen  19  in fluid communication (a) with fluid-retaining chamber  41  (as described below) and (b) with inflatable balloon  22  of balloon-based implant  20  when fluid-conveyance lumen catheter  18  is coupled to inflatable balloon  22 ; a single integral shaft may define both fluid-conveyance lumen catheter  18  and delivery-handle fluid-conveyance lumen tube  35 , or two discrete shafts may define fluid-conveyance lumen catheter  18  and delivery-handle fluid-conveyance lumen tube  35 , respectively, and be coupled together; and   a catheter lumen shaft  26 , which is disposed within catheter fluid-conveyance lumen  19 , and which is in direct reversible connection with balloon-based implant  20  (for example, as described hereinbelow with reference to  FIGS.  6 - 9 C ), longitudinally slidable with respect to delivery handle  11  to shorten or lengthen a length of balloon-based implant  20 .       

     It is noted that because catheter lumen shaft  26  is typically disposed within catheter fluid-conveyance lumen  19 , only a portion of the volume of catheter fluid-conveyance lumen  19  is available for passage of the fluid, i.e., the space between an inner surface of fluid-conveyance lumen catheter  18  and an outer surface of catheter lumen shaft  26 . 
     As shown in  FIG.  2 D , delivery handle  11  comprises:
         a delivery-handle fluid-conveyance lumen tube  35 , which is shaped so as to define a delivery-handle fluid-conveyance lumen  28  in fluid communication with (a) a port  48  at a distal end of fluid-retaining chamber  41  (labeled in  FIGS.  2 B and  2 C ) and (b) catheter fluid-conveyance lumen  19 , for expelling fluid out of fluid-retaining chamber  41 , into catheter fluid-conveyance lumen  19 , and to inflatable balloon  22  of balloon-based implant  20 . The expulsion of the fluid from fluid-retaining chamber  41  inflates inflatable balloon  22  of balloon-based implant  20  during deployment of the implant; and   a delivery-handle lumen shaft  37 , which is disposed within delivery-handle fluid-conveyance lumen  28 , and which is extends from catheter lumen shaft  26  and longitudinally slidable with respect to delivery handle  11 ; a single integral shaft may define both delivery-handle lumen shaft  37  and catheter lumen shaft  26 , or two discrete shafts may define delivery-handle lumen shaft  37  and catheter lumen shaft  26 , respectively, and be coupled together.       

     It is noted that because delivery-handle lumen shaft  37  is typically disposed within delivery-handle fluid-conveyance lumen  28 , only a portion of the volume of delivery-handle fluid-conveyance lumen  28  is available for passage of the fluid, i.e., the space between an inner surface of delivery-handle fluid-conveyance lumen tube  35  and an outer surface of delivery-handle lumen shaft  37 . 
     Typically, a proximal end of delivery-handle fluid-conveyance lumen tube  35  is coupled to port  48 . 
     Delivery system  10  further comprises a cannula extension  33 , which is connected at one end of the cannula extension in fluid communication with fluid-retaining chamber  41 . The other end of cannula extension  33  is configured to be coupled in fluid connection with a fluid source, such as one or more conventional syringes  50 . To this end, cannula extension  33  typically comprises a connector  61 , such as a valve  62  (e.g., a 3-way valve) or a stopcock, which optionally comprises a valve. Cannula extension  33  may be used to fill fluid-retaining chamber  41  at the beginning of the implantation procedure, such as by creating a vacuum within fluid-retaining chamber  41  using a first one of syringes  50 , changing a position of 3-way valve  62 , and then injecting fluid into fluid-retaining chamber  41  using a second one of syringes  50 . Optionally, cannula extension  33  may be used during or after the distal advancement of plunger  30  into fluid-retaining chamber  41 , in order to insert additional fluid into fluid-retaining chamber  41  and consequently into balloon  22  of balloon-based implant  20 . 
     For some applications, catheter lumen shaft  26  is shaped so as to define a catheter guidewire lumen  27  (labeled in  FIG.  2 C ), through which a guidewire and/or a fluid, such as a contrast agent, may be passed. For these applications, delivery handle  11  typically further comprises a delivery-handle guidewire lumen  29  (labeled in  FIG.  2 D ) having a proximal lumen entrance  14  and a distal end in communication with catheter guidewire lumen  27 . While balloon-based implant  20  is in the noninflated and non-deployed configuration  24 , a guidewire (not shown) may be passed through lumen entrance  14  of delivery-handle fluid-conveyance lumen  28 , delivery-handle guidewire lumen  29 , and a guidewire lumen defined by balloon-based implant  20 , for guiding the balloon-based implant and delivery catheter  16  of delivery system  10  to the target area in the subject&#39;s body. The guidewire may be withdrawn proximally after the balloon-based implant reaches the target site. 
     For some applications, as show in  FIG.  2 A , delivery handle  11  comprises a plunger pusher  42 . Optionally, delivery handle  11  further comprises a longitudinal-action position pin  43 , which protrudes from a longitudinal opening  47  through plunger pusher  42  and is positioned distally within longitudinal opening  47 . The length of longitudinal opening  47  sets a maximum distance that pin  43  can move, thereby limiting the maximum distance plunger pusher  42  can move, and setting a maximum amount of fluid that can be expelled from fluid-retaining chamber  41 . Because pin  43  is rotationally constrained by longitudinal opening  47 , the pin may also help stabilize the movement of plunger pusher  42 , by inhibiting rotation of plunger pusher  42  when it moves longitudinally. 
     As shown in  FIGS.  2 B-D  and  2 F-G, double-threaded tube  46  is connected to proximal rotatable user-control knob  31 . Double-threaded tube  46  is shaped so as to define:
         a first thread  64 A that is threadedly coupled to a corresponding second thread  64 B defined by plunger pusher  42  (for example, first thread  64 A may be an external thread, and second thread  64 B may be an internal thread, such as shown, or vice versa, as described hereinbelow regarding balloon-based implant  120  with reference to  FIGS.  4 A-F ), and   a third thread  66 A that is threadedly coupled to a corresponding fourth thread  66 B defined by an actuator  44 , which is described hereinbelow (for example, third thread  66 A may be an internal thread, and fourth thread  66 B may be an external thread, such as shown, or vice versa (configuration not shown)).       

     Actuator  44  is disposed longitudinally slidable in delivery handle  11 , coupled to delivery-handle lumen shaft  37 , which, as mentioned above, extends from catheter lumen shaft  26 . Actuator  44  is longitudinally movable with respect to delivery handle  11  so to shorten or elongate balloon-based implant  20 . 
     Delivery handle  11  is configured such that the rotation of proximal rotatable user-control knob  31  actuates plunger pusher  42  and actuator  44  by rotating double-threaded tube  46 , such that rotation of proximal rotatable user-control knob  31 :
         in a first rotational direction, such as shown in the transition between  FIGS.  2 B-D  and  FIGS.  2 F-G , activates double-threaded tube  46  to concurrently (a) expel at least some of the fluid from fluid-retaining chamber  41  into inflatable balloon  22  of balloon-based implant  20 , via catheter fluid-conveyance lumen  19 , by distally moving plunger pusher  42 , which in turn distally advances plunger  30  within fluid-retaining chamber  41 ; and (b) shorten a length of balloon-based implant  20  (optionally, including a frame  23  thereof), by proximally moving actuator  44 , which in turn proximally pulls catheter lumen shaft  26  via delivery-handle lumen shaft  37 , and   in a second rotational direction opposite the first rotational direction, activates double-threaded tube  46  to concurrently (a) withdraw at least some of the fluid into fluid-retaining chamber  41  from inflatable balloon  22  of balloon-based implant  20 , via catheter fluid-conveyance lumen  19 , and (b) elongate the length of balloon-based implant  20  (optionally, including a frame  23  thereof), by distally moving actuator  44 , which in turn distally pushes catheter lumen shaft  26  via delivery-handle lumen shaft  37  (configuration not shown, but equivalent to transitioning back from  FIGS.  2 F-G  to  FIGS.  2 B-D ).       

     The result of the first transition described above (caused by rotation of proximal rotatable user-control knob  31  in the first rotational direction) is to cause the distal sliding of distal movable membrane  45  of plunger  30  within fluid-retaining chamber  41  and the fluid inflation of balloon  22  of balloon-based implant  20 , concurrently with the shortening of balloon-based implant  20  (e.g., balloon frame  23  thereof), which is connected to actuator  44  via catheter lumen shaft  26  and delivery-handle lumen shaft  37 , to bring balloon-based implant  20  to fully-inflated and shortened deployed configuration  25 , as shown in  FIGS.  2 E-H . 
     The second transition described above (caused by rotation of proximal rotatable user-control knob  31  in the second rotational direction) is the opposite, namely concurrent (a) refilling of fluid-retaining chamber  41  with fluid from balloon  22  and (b) lengthening of balloon-based implant  20 . This may be desired in order to reposition or remove the implant before completion of the implantation procedure, and/or in order to adjust the implant size to better match a cardiovascular defect. 
     Delivery handle  11  is configured such that the rotation of proximal rotatable user-control knob  31  moves plunger  30  within fluid-retaining chamber  41  in a first longitudinal direction by a first distance, and moves catheter lumen shaft  26  in a second longitudinal direction, opposite the first longitudinal direction, by a second distance. For some applications, a ratio of the first and the second distances remains constant over all possible degrees of the rotation proximal rotatable user-control knob  31 . As a result, a ratio of (a) the volume of fluid transferred out of or into fluid-retaining chamber  41  and (b) a change in the length of the balloon-based implant  20  remains constant over all possible degrees of the rotation proximal rotatable user-control knob  31 . This is typically the case during rotation of the proximal rotatable user-control knob  31  in both the first and the second rotational directions. 
       FIG.  2 E  is a cross-sectional view of delivery system  10  highlighting the longitudinal-action position pin  43 , which extends radially outward from longitudinal opening  47  on plunger pusher  42  and is positioned proximally within the longitudinal opening, as result of the shortening of balloon-based implant  20  to deployed configuration  25  actuated by rotation of proximal rotatable user-control knob  31 . The movement of actuator  44  and the related shortening of balloon-based implant  20  is indicated by the position of pin  43 , which is visible through plunger pusher  42 . 
     In this phase, a contrast medium fluid may be injected (such as from a syringe) into lumen entrance  14 , through delivery-handle guidewire lumen  29  and catheter guidewire lumen  27 , to exit distally to balloon-based implant  20 , to visually evaluate by x-ray imaging the adherence of the balloon-based implant to the surrounding target anatomy. 
       FIGS.  2 E-G  show delivery system  10  after it has been actuated to transition balloon-based implant  20  to its fully-inflated and shortened deployed configuration  25 . If it is desired to introduce additional fluid into balloon  22 , such as to achieve greater adherence of balloon-based implant  20  with the surround anatomy, additional fluid may be introduced from cannula extension  33  into delivery-handle fluid-conveyance lumen  28  via fluid-retaining chamber  41  and to balloon  22  of balloon-based implant  20 . 
     The distal end of catheter lumen shaft  26  is decoupled from balloon-based implant  20 , such as by rotation of catheter lumen shaft  26 , e.g., by rotation of proximal lumen entrance  14 . For example, the decoupling techniques described hereinbelow with reference to  FIGS.  7 A-B  may be used. 
     Reference is made to  FIG.  2 H . For some applications, delivery catheter  16  further comprises an outer implant-coupling tube  68 , which is configured to hold delivery catheter  16  coupled to balloon-based implant  20 . For example, a distal connector  86  of delivery catheter  16  may comprise one or more legs that engage one or more respective coupling sites (e.g., slots) of a proximal connector of balloon-based implant  20 , such as labeled in  FIG.  2 H . For example, the legs may be configured to biased radially outward when in an unconstrained, resting state, and may be held radially inward engaging the coupling sites of the proximal connector by outer implant-coupling tube  68 , as shown in  FIG.  1   . Proximal withdrawal of outer implant-coupling tube  68  with respect to balloon-based implant  20  releases the legs, as shown in  FIG.  2 H  (and  FIG.  9 B , described hereinbelow). 
     For some applications, activation of distal user control  32  disconnects balloon-based implant  20  from delivery catheter  16  and thus from delivery system  10 . For example, distal user control  32  may comprise a rotatable knob, rotation of which disconnects balloon-based implant  20  from delivery catheter  16 , in which case distal user control  32  may have a threaded connection with a tube of delivery handle  11 , such that the rotation proximally moves outer implant-coupling tube  68  with respect to delivery handle  11 . Alternatively, distal user control  32  may be slidable with respect to delivery handle  11 , such that sliding of the user control in a proximal direction proximally moves outer implant-coupling tube  68  with respect to delivery handle  11 . 
     For some applications, fluid-retaining chamber  41  has a maximum volume of 50 ml, e.g., 20 ml. 
     For some applications, plunger  30  has a length of between 5 mm and 25 mm, typically 10 mm, and distal movable membrane  45  has a diameter of between 5 mm and 30 mm, typically 15 mm. 
     For some applications, double-threaded tube  46  has a length of between 20 mm and 150 mm, typically 100 mm, when in a closed configuration, and/or a length of between 40 mm and 200 mm, typically 150 mm, when in an open configuration. 
     For some applications, double-threaded tube  46  has a diameter of between 5 and 40 mm, typically 15 mm. 
     For some applications:
         first and second threads  64 A and  64 B have a number of turns of between 2 and 25 and/or a pitch of between 0.5 and 5 mm, and/or   third and fourth threads  66 A and  66 B have a number of turns of between 2 and 25 and/or a pitch of between 0.5 and 5 mm.       

     Reference is now made to  FIG.  3    is a schematic illustration of a delivery system  110  connected to implantable balloon-based implant  20  that is in noninflated and non-deployed configuration  24 , in accordance with an application of the present invention. Other than as described hereinbelow, delivery system  110  is similar to delivery system  10 , described hereinabove with reference to  FIGS.  1  and  2 A -H, and like numerals refer to like parts. Optionally, delivery system  110  may implement any of the features of delivery system  10 , mutatis mutandis. 
     Reference is also made to  FIGS.  4 A-F , which are schematic illustrations of a method of using delivery system  110  for delivering and deploying balloon-based implant  20 , in accordance with an application of the present invention. 
     Delivery system  110  comprises a delivery handle  111  and delivery catheter  16 . Delivery handle  111  comprises proximal rotatable user-control knob  31  that is configured to activate a double-threaded tube  146  within handle  111 . Optionally, delivery handle  111  further comprises distal user control  32  that is configured to release balloon-based implant  20  from delivery catheter  16 , such as described hereinabove for delivery system  10  with reference to  FIG.  2 H . 
     Delivery handle  111  further comprises a fluid-retaining chamber  141 . Delivery handle  111  further comprises plunger  30  that is slidingly disposed in fluid-retaining chamber  141  so as to define distal movable membrane  45  (i.e., a distal surface of the head of plunger  30 ) to draw fluid into fluid-retaining chamber  141  and expel fluid out of fluid-retaining chamber  141 , thereby filling and unfilling fluid-retaining chamber  141 , respectively. As described below, plunger  30  and fluid-retaining chamber  141  may longitudinally move with each other either by longitudinal movement of plunger  30  or by longitudinal movement of fluid-retaining chamber  141 . For example, the fluid may comprise saline. Optionally the fluid may comprise a contrast medium. 
     For some applications, as show in  FIG.  4 A , delivery handle  111  comprises a plunger pusher  142 . Double-threaded tube  146  is connected to proximal rotatable user-control knob  31 . Double-threaded tube  146  is shaped so as to define:
         a first thread  164 A that is threadedly coupled to a corresponding second thread  164 B defined by plunger pusher  42  (for example, first thread  164 A may be an internal thread, and second thread  164 B may be an external thread, such as shown, or vice versa, as described hereinabove regarding balloon-based implant  20  with reference to  FIGS.  2 B-D  and  2 F-G), and   a third thread  166 A that is threadedly coupled to a corresponding fourth thread  166 B defined by an actuator  144 , which is described hereinbelow (for example, third thread  166 A may be an internal thread, and fourth thread  166 B may be an external thread, such as shown, or vice versa (configuration not shown)).       

     For configurations in which first and third threads  164 A and  166 A are both internal threads (as shown) or are both external threads (configuration not shown), typically first and third threads  164 A and  166 A have opposite directions of threading (i.e., one is right-handed and the other left-handed). First and third threads  164 A and  166 A may have the same pitch as each other, or different pitches from one another. 
     Actuator  144  is disposed longitudinally slidable in delivery handle  111 , coupled to delivery-handle lumen shaft  37 , which, as mentioned above, extends from catheter lumen shaft  26 . Actuator  144  is longitudinally movable with respect to delivery handle  111  so to shorten or elongate balloon-based implant  20 . 
     The rotation of proximal rotatable user-control knob  31  actuates plunger pusher  142  and actuator  144  by rotating double-threaded tube  146 , such that rotation of proximal rotatable user-control knob  31 :
         in a first rotational direction, such as shown in the transition between  FIG.  4 A  and  FIG.  2 B , activates double-threaded tube  146  to concurrently (a) expel at least some of the fluid from fluid-retaining chamber  141  into inflatable balloon  22  of balloon-based implant  20 , via catheter fluid-conveyance lumen  19 , by distally moving plunger pusher  142 , which in turn distally advances plunger  30  within fluid-retaining chamber  141 ; and (b) shorten a length of balloon-based implant  20  (optionally, including a frame  23  thereof), by proximally moving actuator  144 , which in turn proximally pulls catheter lumen shaft  26  via delivery-handle lumen shaft  37 , and   in a second rotational direction opposite the first rotational direction, activates double-threaded tube  146  to concurrently (a) withdraw at least some of the fluid into fluid-retaining chamber  141  from inflatable balloon  22  of balloon-based implant  20 , via catheter fluid-conveyance lumen  19 , and (b) elongate the length of balloon-based implant  20  (configuration not shown, but equivalent to transitioning back from  FIG.  2 B  to  FIG.  2 A ).       

     The result of the first transition described immediately above is to cause the distal sliding of distal movable membrane  45  of plunger  30  within fluid-retaining chamber  141  and the fluid inflation of balloon  22  of balloon-based implant  20 , concurrently with the shortening of balloon-based implant  20  (e.g., balloon frame  23  thereof), which is connected to actuator  44  via catheter lumen shaft  26  and delivery-handle lumen shaft  37 , to bring balloon-based implant  20  to fully-inflated and shortened deployed configuration  25 , as shown in  FIG.  4 F . 
       FIG.  4 B  show delivery system  110  after it has been actuated to transition balloon-based implant  20  to a partially-inflated and partially-shortened configuration  190 . 
     For some applications, delivery system  110  is configured to additionally inflate balloon  22  of balloon-based implant  20  without additionally concurrently shortening balloon-based implant  20 , such as shown in the transition between  FIG.  4 B  and  FIG.  4 C . 
     For some of these applications, delivery handle  111  further comprises a length-maintaining fluid user-control knob  180 . Delivery handle  111  is configured such that rotation of length-maintaining fluid user-control knob  180 , in a first rotational direction, proximally moves fluid-retaining chamber  141  within delivery handle  111  while plunger  30  remains longitudinally stationary, as shown in the transition between  FIG.  4 B  and  FIG.  4 C . This relative movement has the effect of expelling additional fluid from fluid-retaining chamber  141  into balloon  22  of balloon-based implant  20 , thereby further inflating the balloon. This relative movement is independent of movement of double-threaded tube  146 , such that during this further expulsion of fluid and inflation of the balloon, actuator  144  remains stationary and the length of balloon-based implant  20  thus remains constant. 
     Typically, rotation of length-maintaining fluid user-control knob  180  in a second rotational direction, opposite the first rotation direction, has the opposite effect, namely drawing some of the fluid from balloon  22  back into fluid-retaining chamber  141 , without changing a length of balloon-based implant  20 . 
     For example, delivery handle  111  may comprise a length-maintaining fluid actuator  182 , which is in threaded communication with length-maintaining fluid user-control knob  180 . Rotation of length-maintaining fluid user-control knob  180  in the first rotational direction causes proximal movement of length-maintaining fluid actuator  182 , which in turn causes the above-mentioned proximal movement of fluid-retaining chamber  141  within delivery handle  111  while plunger  30  remains longitudinally stationary, as shown in the transition between  FIG.  4 B  and  FIG.  4 C . Typically, rotation of length-maintaining fluid user-control knob  180  in the second rotational direction has the opposite effect. 
     For some applications, balloon-based implant  20  is configured such that once it has been shortened to a predetermined length, balloon-based implant  20  becomes irreversibly locked at the predetermined length and a fluid port of the balloon closes, preventing addition or removal of fluid, in order to maintain proper implantation of the implant in the surrounding anatomy, for example using locking mechanism  340 , described hereinbelow with reference to  FIGS.  6  and  7 A -B. Once balloon-based implant  20  become locked, the rotation of proximal rotatable user-control knob  31  in the second rotational direction is no longer possible. However, during the implantation procedure, it may be desired to partially lengthen balloon-based implant  20  and partially unfill balloon  22  thereof in order to reposition or remove the implant before completion of the implantation procedure and/or in order to adjust the implant size to better match a cardiovascular defect. For example, whether it is desired to reposition or remove the implant may be ascertained by injecting contrast medium into lumen entrance  14 , through delivery-handle guidewire lumen  29  and catheter guidewire lumen  27 , to exit distally to balloon-based implant  20 , to visually evaluate by x-ray imaging the balloon-based implant with respect to the surrounding target anatomy. 
     To this end, in some applications, delivery handle  11  comprises a safety latch  186 , which is configured to assume a locked state, such as show in  FIGS.  4 A-C , and an unlocked state, such as shown in  FIGS.  4 D-F . The user can transition the safety latch between its two states, typically using a single finger of the user. Typically, the initial state is the unlocked state. When in the locked state, safety latch  186  blocks double-threaded tube  146  from the completion of the concurrent (a) expulsion of the fluid from fluid-retaining chamber  141  into inflatable balloon  22  and (b) shortening of the length of balloon-based implant  20 , as described above. Blocking this completion prevents the locking of the implant. 
     For example, safety latch may limit distal motion of an element of delivery handle  11 , such as plunger pusher  142 , e.g., a radially-directed tab  192  thereof. 
     Once safety latch  186  has been transitioned to the unlocked state, such as shown in  FIG.  4 D , proximal rotatable user-control knob  31  can be further rotated in the first rotation direction to complete the concurrent (a) expulsion of the fluid from fluid-retaining chamber  141  into inflatable balloon  22  and (b) shortening of the length of balloon-based implant  20 , as described above, and as can be seen in the transition from  FIG.  4 D  to  FIG.  4 E . 
     In addition, if it is desired to introduce additional fluid into balloon  22 , such as to achieve greater adherence of balloon-based implant  20  with the surround anatomy, additional fluid may be introduced from cannula extension  33  into delivery-handle fluid-conveyance lumen  28  (distal to fluid-retaining chamber  141 ) and to balloon  22  of balloon-based implant  20 . 
     Reference is now made to  FIGS.  5 A-F , which are schematic illustrations of a delivery catheter  216 , in accordance with an application of the present invention. Delivery catheter  216  may optionally be used in combination with delivery system  10 , described hereinabove with reference to  FIGS.  1  and  2 A -H, or delivery system  110 , described hereinabove with reference to  FIGS.  3  and  4 A -F. Alternatively, delivery catheter  216  may be used with another delivery system. 
       FIG.  5 A  is a cross-sectional view of delivery catheter  216  with delivery handle  11  and delivery catheter  216  connected to balloon-based implant  20 , in a noninflated and non-deployed configuration  24 , in accordance with an application of the present invention. 
     Delivery catheter  216  comprises a double fluid-retaining chamber  13  and an inflation catheter  52  which is directly connected to balloon-based implant  20 . Double fluid-retaining chamber  13  is shaped so as to define an opening  51  on its surface, which places in contact the surrounding of delivery catheter  216  with one of two internal sub-chambers of double fluid-retaining chambers  13 . 
       FIG.  5 B  is a cross-sectional view of delivery catheter  216  showing the inside of double fluid-retaining chamber  13 , in accordance with an application of the present invention. The inside of double fluid-retaining chamber  13  is shaped so as to define a proximal chamber  55  and a distal chamber  57 . 
     An opening  51  through the external surface of double fluid-retaining chamber  13  allows the fluid surrounding this opening to enter proximal chamber  55 . During a cardiovascular procedure this fluid is blood  60 . Opening  51  and double fluid-retaining chamber  13  may be placed equally proximally or distally along delivery catheter  216 . Blood  50  can enter proximal chamber  55  only when opening  51  and groove  53  are aligned with each other. A plunger  56  is positioned within proximal chamber  55  and it is placed distally at the beginning of the procedure, at a longitudinal position X. 
     As shown in  FIG.  5 C , plunger  56  is retracted proximally to a longitudinal position Y, filling internal fluid proximal chamber  55  with blood  60 . The chamber internal volume or wall may be pre-treated with anticoagulant solution to avoid blood clotting within the chamber. 
     As shown in  FIG.  5 D , chamber distal end  54  is rotated independently from distal chamber  57 , until its groove  53  is in free contact with internal distal chamber  57 , occluding by this rotation opening  51  which is located on the external surface of double fluid-retaining chamber  13 . 
     As shown in  FIG.  5 E , plunger  56  is advanced to distal longitudinal position X, pushing blood  60  from proximal chamber  55  to distal chamber  57  to inflation catheter  52  to balloon-based implant  20 . Blood  60  passes through distal chamber  57  to inflate balloon  22  and to conform balloon frame  23 . The plunger may be advanced until sufficient inflation is observed with balloon-based implant  20  that transition to a fully inflated and deployed configuration  204 . Balloon-based implant  20  may be now detached from delivery catheter  216  and delivery system  10 , unless the operator wants to deflate the balloon by retracting the plunger to proximal longitudinal position Y. 
       FIG.  5 F  provides a view of delivery system  10  and of the internal components of delivery catheter  216  and of double fluid-retaining chamber  13 , in accordance with an application of the present invention. 
     These steps are reversible and may be used for deflating balloon-based implant  20 . These steps may be performed also more than once in series, to provide more inflation volume to balloon-based implant  20 . 
       FIG.  6    is a schematic illustration of a balloon-based occlusion device  20  for occluding a left atrial appendage (LAA), in accordance with an application of the present invention. Occlusion device  20  may be used with delivery system  10 ; described hereinabove with reference to  FIGS.  1  and  2 A -H, delivery system  110 , described hereinabove with reference to  FIGS.  3  and  4 A -F; and/or delivery catheter  216 , described hereinabove with reference to  FIGS.  5 A-F . 
     Reference is also made to  FIGS.  7 A-B , which are schematic cross-sectional illustrations of occlusion device  20  and a distal portion of the delivery system, in accordance with an application of the present invention.  FIG.  7 A  shows occlusion device  20  with a locking mechanism  340  thereof in an unlocked state and a valve  342  thereof in an open state, as described hereinbelow.  FIG.  7 B  shows occlusion device  20  with locking mechanism  340  in a locked state and valve  342  in a closed state, as described hereinbelow. 
     For some applications, occlusion device  20  comprises:
         compliant balloon  22  defining a fluid-tight balloon chamber  332 ;   an actuating shaft  334 , which is (a) disposed at least partially within balloon chamber  332 , (b) connected to a distal end portion  336  of balloon  22 , and (c) longitudinally moveable with respect to a proximal end portion  338  of balloon  22  so as to set a distance between distal and proximal end portions  336  and  338  of balloon  22 ;   locking mechanism  340 , which is configured to assume locked and unlocked states, as shown in  FIGS.  7 B and  7 A , respectively; and   valve  342 .       

     Occlusion device  20  is configured such that proximally longitudinally moving actuating shaft  334  expands balloon  22  in a radial or a lateral direction by shortening the distance between distal and proximal end portions  336  and  338  of balloon  22  to a desired distance. 
     Locking mechanism  340  is configured, when in the locked state, to maintain, between distal end portion  336  of balloon  22  and proximal end portion  338  of balloon  22 , the distance set using actuating shaft  334 . 
     For some applications, occlusion device  20  is shaped so as to define a fluid flow path  344  along (e.g., alongside, as shown) a portion of actuating shaft  334 . Valve  342  is configured to selectively:
         allow fluid flow between fluid flow path  344  and balloon chamber  332  when valve  342  is in the open state, as shown in  FIG.  7 A , or   block fluid flow between fluid flow path  344  and balloon chamber  332  when valve  342  is in the closed state, as shown in  FIG.  7 B .       

     For some applications, occlusion device  20  is configured such that reduction of the distance, by proximal longitudinal movement of actuating shaft  334 :
         to a first predetermined distance between distal and proximal end portions  336  and  338  of balloon  22  automatically transitions valve  342  from the open state to the closed state, as shown in the transition from  FIG.  7 A  to  FIG.  7 B , and   to a second predetermined distance between distal and proximal end portions  336  and  338  of balloon  22  automatically transitions locking mechanism  340  from the unlocked state to the locked state, as also shown in the transition from  FIG.  7 A  to  FIG.  7 B .       

     For some applications, the first predetermined distance does not equal the second predetermined distance. For example, the first predetermined distance may be less than the second predetermined distance, such that the proximal longitudinal movement of actuating shaft  334  first automatically transitions valve  342  from the open state to the closed state and subsequently automatically transitions locking mechanism  340  from the unlocked state to the locked state. Alternatively, the first predetermined distance may be greater than the second predetermined distance, such that this sequence is reversed. 
     Further alternatively, for some applications, the first predetermined distance equals the second predetermined distance, such that the proximal longitudinal movement of actuating shaft  334  simultaneously automatically transitions valve  342  from the open state to the closed state and automatically transitions locking mechanism  340  from the unlocked state to the locked state. 
     As described hereinabove, in order to cause the above-mentioned proximal longitudinal movement of actuating shaft  334 , the delivery system comprises a catheter lumen shaft  26 , which is releasably coupled a proximal end portion of actuating shaft  334 . For example, a distal portion of catheter lumen shaft  26  may comprise a pull-shaft coupling  348 , which may, for example, be shaped so as to define a thread that removably engages a corresponding thread defined by the proximal end portion of actuating shaft  334 . Rotation of catheter lumen shaft  26  disengages shaft coupling  348  from the corresponding thread defined by the proximal end portion of actuating shaft  334 . 
     Occlusion device  20  is configured to be releasably connected to the delivery system. Occlusion device  20  is configured such that fluid flow path  344  is coupled in fluid communication with the delivery system when occlusion device  20  is releasably connected to the delivery system, such as shown in  FIGS.  7 A-B . 
     For some applications, actuating shaft  334  is shaped so as to define, at least in part, a distal tip  350  disposed at distal end portion  336  of balloon  22 , as shown in  FIGS.  6  and  7 A -B. 
     For some other applications, occlusion device  20  further comprises a distal tip disposed at distal end portion  336  of balloon  22 , and actuating shaft  334  is connected to the distal tip (configuration not shown). 
     Alternatively or additionally, for some applications, occlusion device  20  further comprises a proximal base disposed at proximal end portion  338  of balloon  22 , and actuating shaft  334  is moveable (e.g., longitudinally or rotationally) with respect to the proximal base (configuration not shown). 
     For some applications, valve  342  is disposed along actuating shaft  334 , such as shown in  FIGS.  7 A-B . 
     For some applications, occlusion device  20  further comprises a proximal tube  352 , which is axially fixed with respect to proximal end portion  338  of balloon  22 . Actuating shaft  334  is slidably disposed partially within proximal tube  352 , e.g., so as to indirectly connect actuating shaft  334  to proximal end portion  338  via proximal tube  352 . For some of these applications, occlusion device  20  is shaped so as to define fluid flow path  344  along the portion of actuating shaft  334 , radially between an external surface of actuating shaft  334  and an internal surface of proximal tube  352 , such as shown in  FIGS.  7 A-B . Optionally, valve  342  is disposed along actuating shaft  334 . 
     For some applications, valve  342  comprises a seal  354  around at least a portion of (e.g., entirely around) the external surface of actuating shaft  334 . Valve  342  is configured to assume (a) the open state when seal  354  is disposed at one or more first axial positions  356 A with respect to proximal tube  352  (one such first axial position is shown in  FIG.  7 A ), and (b) the closed state when seal  354  is disposed at one or more second axial positions  356 B with respect to proximal tube  352  (one such second axial position is shown in  FIG.  7 B ). The one or more second axial positions  356 B are proximal to the one or more first axial positions  356 A. For example, seal  354  may comprise an O-ring, as shown in  FIGS.  7 A-B , e.g., a single O-ring or a series of O-rings. Optionally, one or more additional seals  319 , e.g., one or more O-rings, are provided to provide further stabilization an alignment of the distal tube inside the proximal tube by friction. 
     For some applications, seal  354 , actuating shaft  334 , and proximal tube  352  are arranged such that seal  354  blocks fluid flow out of a distal end  358  of proximal tube  352 , at least when seal  354  is disposed at the one or more first axial positions  356 A with respect to proximal tube  352 , such as shown in  FIG.  7 A . Alternatively or additionally, friction between seal  354  and the inner surface of proximal tube  352  increases structural stability, and/or enables stepwise inflation/implantation. 
     For some applications, a wall of proximal tube  352  is shaped so as to define one or more tabs  360  through the wall. The one or more tabs  360  are biased to flex radially inward. When valve  342  is in the open state, as shown in  FIG.  7 A , fluid flow path  344  passes through the wall between respective proximal ends  362  of the one or more tabs  360  and a non-tabbed portion  364  of the wall axially adjacent the one or more tabs  360 , such as proximal to the one or more tabs  360 , as shown. 
     For some applications, the external surface of actuating shaft  334  is shaped so as to define one or more protrusions  366  around at least a portion of (e.g., entirely around) actuating shaft  334 . Proximal ends  362  of the one or more tabs  360  are shaped so as to prevent distal movement of the one or more protrusions  366  when the one or more protrusions  366  are disposed proximal to the proximal ends  362  of the one or more tabs  360 , such as shown in  FIG.  7 B , thereby causing locking mechanism  340  to assume the locked state. 
     For some applications, occlusion device  20  further comprises a proximal LAA-orifice cover  21 , which:
         is fixed to proximal tube  352  radially surrounding proximal tube  352 ,   is configured to assume a radially-compressed state, such as shown in  FIG.  8 A , described hereinbelow, and a radially-expanded state, such as shown in  FIGS.  6  and  7 A -B,   comprises frame  372  and a covering  374  fixed to frame  372 ,   when in the radially-expanded state, is generally orthogonal to proximal tube  352  and has a greatest dimension, measured perpendicular to proximal tube  352 , of at least 20 mm (e.g., at least 20 mm), no more than 50 mm (e.g., no more than 30 mm), and/or between 20 and 50 mm (e.g., between 20 and 30 mm), and   is typically indirectly connected to balloon  22  via proximal tube  352  and is not directly connected to balloon  22 .       

     This indirect connection of proximal LAA-orifice cover  21  to balloon  22  generally prevents an anodic reaction between the typically super-elastic (e.g., Nitinol) material of frame  372  of proximal LAA-orifice cover  21  and the typically plastically deformable (e.g., stainless steel) material of struts  380 , described hereinbelow. Such a reaction might have occurred if the two elements were instead welded or otherwise bonded together in contact with each other. (Connection of the elements via an independent and passive element, such as an internal tube or shaft, also does not cause such a reaction.) Alternatively, proximal LAA-orifice cover  21  is directly connected to balloon  22 , such as if frame  372  comprises a different plastically-deformable material, such as titanium. 
     For some applications, occlusion device  20  further comprises orifice-support stent  290 , described hereinbelow with reference to  FIGS.  8  and  9 A -B. 
     For some applications, actuating shaft  334  is shaped so as to define a guidewire lumen  376  for slidingly receiving therein a guidewire and/or passage of fluid injected under pressure, such as contrast media injected from the proximal handle of the delivery tool to the distal end of the occlusion device. Alternatively, for other applications, actuating shaft  334  is not shaped so as to define a guidewire lumen. 
     For some applications, compliant balloon  22  comprises a compliant material selected from the group consisting of: polycaprolactone (PCL), polyglycolic acid (PGA), polylactic acid (PLA), and polydioxanone (PDO or PDS), silicone, polyurethane, polytetrafluoroethylene (PTFE), polymethylmethacrylate, polyether ether ketone (PEEK), polyvinyl chloride, polyethylene terephthalate, nylon, polyamide, polyamide, and polyether block amide (PEBA). 
     For some applications, balloon  22  has an average wall thickness of between 100 and 5000 microns. Alternatively or additionally, for some applications, balloon  22  has, at a thinnest portion of a wall of balloon  22 , a thinnest wall thickness of between 20 and 500 microns. 
     For some applications, occlusion device  20  further comprises connecting struts  380  fixed to distal end portion  336  of balloon  22  and to proximal end portion  338  of balloon  22 . Struts  380  may be disposed inside balloon  22 , outside balloon  22 , or some inside and some outside balloon  22 . For some applications, struts  380  are arranged as a frame. For some applications, struts  380  are arranged in a cage-like arrangement. Typically, struts  380  comprise a plastically-deformable material, such as stainless steel or titanium. Typically, struts  380  help shape balloon  22  as the balloon chamber is inflated and/or the balloon is shortened. 
     Typically, occlusion device  20  is configured such that inflation of balloon chamber  332  plastically deforms connecting struts  380 . For some applications, occlusion device  20  is configured such that shortening of balloon  22  plastically deforms connecting struts  380 . 
     For some applications, struts  380  are configured such that inflation of balloon chamber  332  primarily causes radial deformation of struts  380 , rather than deformation of the struts in a distal or proximal direction. To this end, first lateral portions  381 A of struts  380  arranged along a lateral surface of balloon  22  may be more compliant than second end portions  381 B of struts  380  arranged on a distal surface of balloon  22  and/or on a proximal surface of balloon  22 . For example, first lateral portions  381 A may be thinner than second end portions  381 B, as shown in  FIG.  6   , and/or first lateral portions  381 A may be shaped to be more compliant, e.g., have a serpentine (e.g., sinusoidal) shape, as shown. Typically, first lateral portions  381 A are oriented parallel to a central longitudinal axis of occlusion device  20 . 
     Reference is now made to  FIGS.  8 A-F , which are schematic illustrations of steps of a method of deploying occlusion device  20  using the delivery system, in accordance with an application of the present invention. 
     Reference is also made to  FIGS.  9 A-C , which are schematic cross-sectional views of a portion of the steps of the method shown in  FIGS.  8 A-F , in accordance with an application of the present invention. 
       FIG.  8 A  schematically shows occlusion device  20  releasably disposed in a radially-compressed state within a sheath  382  of the delivery system. Typically, a greatest distance between proximal end portion  338  of balloon  22  and distal end portion  336  of balloon  22  is at least 8 mm (e.g., at least 15 mm), no more than 80 mm (e.g. no more than 60 mm), and/or between 8 and 80 mm (e.g., between 15 and 60 mm), when occlusion device  20  is in this radially-compressed state. 
     For some applications, occlusion device  20  comprises a proximal connector  384  that is configured to releasably connect occlusion device  20  to a correspondingly configured distal connector  86  of the delivery system, such as described hereinabove with reference to  FIG.  2 H . 
     For some applications, distal connector  86  comprises one or more legs that engage one or more respective coupling sites (e.g., slots) of proximal connector  384 , such as perhaps best seen in  FIGS.  9 A-C . For example, the legs may be configured to biased radially outward when in an unconstrained, resting state, and may be held radially inward engaging the coupling sites of proximal connector  384 , such as by outer implant-coupling tube  68 , as shown in  FIG.  9 A . Proximal withdrawal of outer implant-coupling tube  68  with respect to occlusion device  20  release the legs, as shown in  FIG.  9 B . 
     Alternatively, proximal connector  384  is shaped so as to define a thread (configuration not shown). 
       FIG.  8 B  shows occlusion device  20  after sheath  382  has been proximally withdrawn, thereby releasing occlusion device  20 .  FIG.  8 B  also shows proximal LAA-orifice cover  21  in its radially-expanded state. Typically, frame  372  of proximal LAA-orifice cover  21  comprises a shape-memory memory, e.g., a super-elastic metal, which causes cover  21  to automatically transition to the radially-expanded state upon release from sheath  382 . Balloon  22  remains in a non-inflated, elongate configuration at this stage of deployment. 
     Typically, a healthcare worker places the distal end of occlusion device  20  into the LAA, using delivery system navigation. 
     As shown in  FIGS.  8 C-D , the healthcare worker inflates balloon chamber  332 .  FIG.  8 C  shows occlusion device  20  upon partial inflation of balloon chamber  332 , while  FIG.  8 D  shows occlusion device  20  upon complete inflation of balloon chamber  332 . Balloon  22  may be inflated by filling balloon chamber  332  with any fluid, including but not limited to saline solution (optionally comprising a contrast medium), blood (e.g., autologous blood), foam, and/or a glue (e.g., a gel, a liquid polymer that can change its proprieties to become rigid, or a hydrogel that remains a gel or self-cures at body temperature). 
     For some applications, struts  380  are shaped so as to define a plurality of spikes  389  that are initially generally axially oriented, as shown in  FIG.  8 C , and are configured to extend more radially upon expansion of balloon  22  to serve as tissue-engaging barbs, as shown in  FIG.  8 D . 
       FIGS.  8 E and  9 A  show occlusion device  20  after (a) valve  342  has transitioned from the open state to the closed state, (b) actuating shaft  334  has been proximally longitudinally moved to expand balloon  22  in a radial or a lateral direction by shortening the distance between distal and proximal end portions  336  and  338  of balloon  22  to a desired distance, and (c) locking mechanism  340  has transitioned from the unlocked state to the locked state, as described hereinabove with reference to  FIGS.  7 A-B . Typically, after balloon  22  has been finally filled, actuating shaft  334  is proximally longitudinally moved to expand balloon  22  in a radial or a lateral direction by shortening the distance between distal and proximal end portions  336  and  338  of balloon  22  to a desired distance. Proximal connector  384  of occlusion device  20  is still releasably connected to correspondingly configured distal connector  86  of the delivery system. 
       FIGS.  8 F and  9 B -C show occlusion device  20  after proximal connector  384  of occlusion device  20  has been released from distal connector  86  of the delivery system. 
       FIG.  9 C  also shows occlusion device  20  after catheter lumen shaft  26  has been decoupled from the proximal end portion of actuating shaft  334 , such as by rotating catheter lumen shaft  26  to unscrew it, as described hereinabove. 
     Reference is now made to  FIG.  20   , which is a schematic illustration of occlusion device  20  implanted to occlude an LAA  100 , in accordance with an application of the present invention. As can be seen, balloon  22  is disposed within LAA  100 , and proximal LAA-orifice cover  21  is disposed in a left atrium  102  outside LAA  100 , against the atrial wall surrounding the orifice of LAA  100 , thereby creating a continuum with the atrium at the LAA level. Typically, proximal LAA-orifice cover  21  protrudes only minimally because of its relatively flat shape, so as not to interfere with blood flow and not to cause thrombosis. Typically, struts  380  provide most of the anchoring of occlusion device  20 , and balloon  22  provides most of the sealing of the LAA. In addition, in configurations in which covering  374  of proximal LAA-orifice cover  21  is blood-impermeable, proximal LAA-orifice cover  21  provides additional sealing of the LAA, primarily to inhibit creation of thrombi on the balloon surface at the orifice level. 
     For some applications, proximal LAA-orifice cover  21  is asymmetric about proximal tube  352 , e.g., elliptical or with a radius greater in one direction than in the perpendicular direction. 
     For some applications, proximal LAA-orifice cover  21  is configured to have an adjustable greatest dimension measured perpendicular to proximal tube  352 . For example, rotation of a proximal LAA-orifice cover  21  adjustment mechanism may adjust the greatest dimension. 
     For some applications, covering  374  of proximal LAA-orifice cover  21  is blood-permeable, so as to serve as filter for the passage of blood in and out of the LAA. For other applications, covering  374  is not blood-permeable, so as to create a secondary sealing of the LAA in addition to the sealing provided by balloon  22 . 
     For some applications, proximal LAA-orifice cover  21  is bioresorbable and/or drug-eluting. 
     For some applications, occlusion device  20  is implanted to treat paravalvular leak, for example as described in  FIGS.  13 A-B  of PCT Publication WO 2020/060587 to Maisano et al., which is incorporated herein by reference. 
     In the context of the present disclosure, the terms “distal” and “proximal” are used accordingly to their standard meaning in the field of percutaneous cardiovascular devices. The term “proximal” refers to those components of the device assembly which, when following a delivery catheter during percutaneous delivery, are closer to the end of the catheter that is configured for manipulation by the user (e.g., a delivery handle manipulated by a physician). The term “distal” is used to refer to those components of the device assembly that are more distant from the end of the catheter that is configured for manipulation by the user and/or that are inserted farther into the body of a patient. 
     The term “compliant” used herein in relation with balloons or with structural components implies a deformability that substantially follows an applied force. Accordingly, a “compliant balloon” means a balloon which progressively expands under the effect of increasing radial pressure as long as a certain burst pressure is not exceeded. 
     As used herein, the term “strut” means an elongate structural element which can be formed, e.g., a thin wire, rod, or thick-walled tube, all of which do not necessarily have a circular cross section. 
     In an embodiment, the techniques and apparatus described herein are combined with techniques and apparatus described in one or more of the following patent applications, which are assigned to the assignee of the present application and are incorporated herein by reference:
         European Patent Application Publication EP 3 459 469 A1 to Maisano et al.;   PCT Publication WO 2019/057950 to Maisano et al.;   US Patent Application Publication 2020/0275935 to Maisano et al.;   PCT Publication WO 2020/060587 to Maisano et al.;   U.S. application Ser. No. 17/207,074, filed Mar. 10, 2021;   U.S. Provisional Application 62/906,393, filed Sep. 26, 2019;   International Application PCT/IL2020/051041, filed Sep. 24, 2020; and/or   U.S. Provisional Application 62/994,465, filed Mar. 25, 2020.       

     It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description.