Advanced actuation mechanisms and methods of operation for fluid movement and pressurization devices - Patents.com

Abstract

A fluid movement and pressurization device comprising a housing, a first piston within the housing, a plunger extending from the housing and having a second piston thereon, and an actuator operable to selectively lock the piston to either the housing or the plunger depending on the position of the second piston within the housing. In effect, the actuator has a first locking mechanism for locking and unlocking the first piston relative to the housing and a second locking mechanism for locking and unlocking the plunger relative to the piston. Thus, the first locking mechanism is not only a locking mechanism but also an actuating mechanism for actuating the second locking mechanism.

Description

[Technical field]

[0001] The present invention relates generally to mechanisms and methods for fluid pressurization to inflate and deflate catheter balloons and the like, and more particularly to a device having a plunger actuation mechanism that is highly intuitive, easy to use and allows for seamless operation.

[0002] Fluid pressurization devices are used to selectively deliver or release measured volumes of fluid under high pressure inside blood vessels for balloon angioplasty and stent delivery procedures, as well as other types of balloon catheter driven procedures including the treatment of aortic aneurysms and delivery of heart valves. Large piston, high volume fluid delivery devices for this purpose often rely on a plunger screw and nut mechanism to provide the mechanical advantage required for pressurization. Due to the typically large piston diameter, a typical 40 mL transfer device may require a plunger force load of 92 lbf (41.7 kgf) to expand a large volume balloon to 8 atmospheres (117.6 psi). Procedures requiring large volume transfer require the balloon expansion of the catheter to occur more quickly than would be possible using a plunger screw mechanism. Examples of such procedures include balloon expansion of endovascular stent grafts to treat abdominal aortic aneurysms (AAA) and the placement and expansion of aortic valves in transcatheter aortic valve (TAVR) procedures. During these procedures, the balloon expansion of the catheters used to deliver such expandable prostheses completely obstructs vital circulatory blood flow within the body. In such cases, it is desirable to limit the time of blood flow disruption during balloon expansion to the order of a few seconds. Under such conditions of use, there is simply not enough time for the clinician to rotate the plunger screw mechanism to achieve the required pressure level in the delivery balloon. Furthermore, in some such procedures, the expansion of the stent must be limited to the desired balloon diameter to avoid distorting the stent or heart valve during delivery, so the amount of fluid delivered, rather than pressure, is the necessary delivery control factor. In such cases, a precise, predetermined amount of working fluid must be loaded into the inflation device, and subsequently, all of the working fluid within the device must be completely displaced during balloon expansion to deliver the entire amount to the catheter balloon. As such, such procedures require very specialized inflation devices.

[0003] Previously improved inflation devices to achieve full pressure balloon expansion use smaller diameter pistons that allow the clinician to reach pressures of, for example, 8 atmospheres by applying a straight manual plunger force in the range of 50-52 lbf (22.7-23.6 kgf). This type of balloon inflation device is often used because it allows the clinician to quickly and completely expel the contents of the inflation device into the stent delivery balloon by successive manual compressions of the plunger without relying on a plunger screw and nut mechanism. To achieve the required fluid volume with this smaller piston approach, the plunger stroke is longer compared to larger piston devices, and therefore a significantly longer bore is required. In practice, manufacturing such a long and small diameter bore in the device barrel has proven difficult for the plastic molding process typically used to manufacture these disposable devices. This plastic molding challenge is compounded by the need to manufacture the device bore with little or no draft (bore taper to aid the part molding process) to ensure reliable piston sealing during use.

[0004] It is possible to rapidly expand large balloons to full pressure with more achievable plunger forces in the range of 50-52 lbf, but it has been recognized that even this level of force is beyond the reach of some clinicians, forcing them to use the plunger screw and nut mechanism of the inflation device to achieve the final pressurization of the catheter balloon. This extra step to achieve full fluid delivery and balloon expansion dramatically impedes the prosthesis wear time in a procedure that should be completed in just a few seconds. Unfortunately, while the ergonomic benefits of a smaller piston and bore could further reduce the user's throwing force, the practical limitations of the molding process required to manufacture the device severely compromise the manufacturability of the device. While it may be possible to add a small secondary piston, manually switching between a pair of pistons is unnecessarily confusing and cumbersome for users whose past training and experience have conditioned them to the simplicity of applying continuous forces to a single plunger to accomplish a syringe-like task.

[0005] Examples of prior art multiple piston single barrel syringe designs include the devices disclosed in U.S. Patent Nos. 3,749,084, 4,583,978 and 4,702,737. All three of these patents disclose multi-dose syringes having more than one piston for delivering multiple individual doses from a single large charge of medical fluid.

[0006] U.S. Patent No. 4,476,866 discloses a dual piston syringe designed to first advance a smaller, internal piston to create a preliminary high pressure condition, invert the balloon, and then move the larger piston after the plunger thumb button of the smaller piston bottoms out to fill at a lower pressure.

[0007] U.S. Pat. No. 4,758,223 discloses a syringe barrel having coaxially arranged dual bores housing a user-selectable dual piston plunger arrangement such that a larger piston and a smaller piston are independently operable within each syringe barrel bore.

[0008] US Patent Publication US2021 / 0085952 discloses a dual piston inflation device having a main piston assembly with a one-way valve and containing an axially disposed inner bore adapted to receive an operable plunger with a second, smaller piston. In operation, when the device is filled with hydraulic fluid, pressure against the smaller piston plunger should first drive the larger piston distally to deliver hydraulic fluid to the balloon, provided that the valve in the larger piston has sufficient resistance to open in response to the pressure buildup between it and the smaller piston. When the larger piston encounters a distally mounted "opening protrusion" mechanism in the barrel of the larger piston designed to open the valve, fluid under pressure created by the smaller piston can be delivered from the central lumen of the valve opening mechanism. This design is similar in concept and principle of operation to the dual dose syringe disclosed in the previously cited US Patent No. 4,702,737.

[0009] U.S. Patents 9,452,279 and 10,238,843 disclose highly complex multi-piston syringe designs with three coaxial pistons within. The intent of this device is to move a larger volume of fluid to a pressure lower than the smaller pistons can deliver alone, and then reduce the user force required to deliver a higher pressure with the smaller pistons. In operation, the larger volume can be moved by moving all three pistons proximally together until a trigger pressure is reached in the fluid chamber. When that trigger pressure is reached, the largest piston is moved proximally against the advanced plunger handle, both of which trigger a sequence of events that brings the middle piston into locking engagement with the housing and releases the smaller piston to advance distally alone. This shift occurs a) when a certain fluid chamber pressure is reached, or b) when the operator drives with sufficient force against the end of the syringe bore if the trigger pressure has not been reached. It should also be recognized that in either scenario, the pressure at which this shift occurs is tightly controlled by the stiffness of the flexible polymer fingers that mate with the plunger stop and the friction that must be overcome to disengage these fingers from the mating plunger stop. The inherent variability of such mechanisms makes them unsuitable for use in the delivery of stents that require size control solely through the delivery of precise fluid volumes instead of pressure. The fact that the function of this device is pressure dependent limits its suitability for applications requiring total delivery of a precisely set amount of fluid.

[0010] Although several prior art devices exist, there remains a need for an advanced balloon catheter inflation device that requires less user input during rapid large balloon stent delivery procedures. Summary of the Invention

[0011] It is an object of embodiments of the present invention to provide an advanced balloon catheter inflation device that requires less input from the user.

[0012] Another object of an embodiment of the present invention is to provide an advanced balloon catheter inflation device that is configured so that the operation of the device only requires the user to rapidly drive its plunger distally inward to move the working fluid into the catheter balloon and, once full filling is reached, to fully withdraw the plunger to expel the delivered fluid and collapse the balloon.

[0013] Another object of an embodiment of the present invention is to provide an advanced balloon catheter inflation device that reduces the required end-of-fill user input delivery force.

[0014] It is yet another object of an embodiment of the present invention to provide an advanced balloon catheter inflation device configured to reliably accomplish a procedure without relying on the assistance of a threaded plunger.

[0015] It is yet another object of an embodiment of the present invention to provide an advanced balloon catheter inflation device that does not require an excessively longer and smaller bore to achieve reduced user thrust force to deliver the same volume of fluid.

[0016] It is yet another object of an embodiment of the present invention to provide an advanced balloon catheter inflation device having a piston bore that is completely open and unobstructed by valves or other air or fluid trapping mechanisms.

[0017] Briefly, embodiments of the present invention provide a fluid movement and pressurization device comprising a housing, a first piston within the housing, a plunger extending from the housing and having a second piston thereon, and an actuator operable to selectively lock the first piston to either the housing or the plunger depending on the position of the second piston within the housing. [Brief description of the drawings]

[0018] The organization and mode of structure and operation of the present invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which like reference numerals identify like elements and in which: [Figure 1] 1 is a graph showing plunger force and amount of fluid delivered to a catheter balloon. [Diagram 2] FIG. 1 is an exploded perspective view of an advanced inflation device according to an embodiment of the present invention. [Diagram 3] FIG. 1 is a perspective view of an assembled advanced inflation device including a delivery balloon catheter and an expandable prosthesis. [Figure 4A] FIG. 4A is a partial cross-sectional view taken along plane 4A-4A of FIG. 3 showing the lock-slide assembly of the advanced expansion device, illustrating the state of the lock-slide assembly while the plunger is locked onto the large piston. [Figure 4B] FIG. 4B is an enlarged view of a portion of FIG. 4A. [Figure 4C] FIG. 4C is a cross-sectional view taken along line 4C-4C of FIG. 4B. [Figure 5A] FIG. 4B is similar to FIG. 4A but shows a different state of the locking slide assembly, specifically when the plunger is unlocked from the large piston. [Figure 5B] FIG. 5B is an enlarged view of a portion of FIG. 5A. [Figure 5C] FIG. 5C is a cross-sectional view taken along line 5C-5C of FIG. 5B. [Figure 6A] FIG. 4B is similar to FIG. 4A, but shows a different state of the lock-slide assembly, specifically, the large piston is latched to the device housing by the biasing bolt and the plunger with the small piston is mid-travel. [Figure 6B] FIG. 6B is an enlarged view of a portion of FIG. 6A. [Figure 6C] FIG. 6C is a cross-sectional view taken along line 6C-6C of FIG. 6B. [Figure 7A] FIG. 4B is similar to FIG. 4A but shows a different state of the locking slide assembly, specifically, the large piston is midway through its travel and locked to the plunger after being unlocked from the biasing bolt. [Figure 7B] FIG. 7B is an enlarged view of a portion of FIG. 7A. [Figure 8] Similar to FIG. 4A, but showing the plunger unlocked from the large piston and the large piston in a fully distal, ejected position locked to the device housing by a biasing bolt. [Figure 9] Similar to FIG. 4A, but showing the plunger in the fully proximal, filling position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] While the invention may be embodied in different forms, specific embodiments have been shown in the drawings and will be described in detail herein, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the precise form illustrated.

[0020] Disclosed herein is an advanced balloon catheter inflation device that requires less user input force during rapid large balloon stent delivery procedures than the improved inflation device described above. This approach effectively takes into account the non-linear rise in plunger force during balloon delivery of large expandable prostheses, with particular emphasis on the need for high force generated at the end of balloon filling. As shown in the example of curve "A" in FIG. 1 for the improved single piston inflation device described above, the rate of plunger force begins to increase significantly when the balloon is 50% to 80% filled, before the remaining 50% to 20% of inflation fluid has been delivered. Operation of the advanced balloon catheter inflation device disclosed herein simply requires the user to rapidly drive the plunger distally inward to move the working fluid into the catheter balloon, and then fully withdraw the plunger to expel the delivered fluid and collapse the balloon after full filling is reached. This device has the ability to reduce the required end-of-fill user input delivery force of the previously described improved smaller piston device, for example from 50-52 lbf to 30-32 lbf, thereby allowing less physically powerful practitioners to quickly and comfortably deliver endovascular aortic stent grafts or perform TAVR procedures. Importantly, these procedures can be performed without resorting to the assistance of a threaded plunger, which is often required with other such devices. Additionally, important from a manufacturing standpoint is the fact that this advanced device does not require an excessively longer and smaller bore than the previously described improved device to achieve a reduction in user throw force to deliver the same volume of fluid. In fact, in this example advanced inflation device, the device can actually be made shorter, whatever the travel. Additionally, the travel ratio between the two pistons can be adjusted to optimally match the desired plunger throw force for a particular delivery balloon filling response.Finally, the advanced balloon catheter inflation device is designed such that its piston bore is completely open and unobstructed by valves or other air or fluid trapping mechanisms, such as the annular dead volume surrounding the protrusion of the valve opening in the design shown in the above-mentioned U.S. Patent Application Publication No. US2021 / 0085952. Thus, without valve obstruction, the advanced inflation device disclosed herein can easily and quickly purge all air to ensure accurate filling during priming and accurate fluid delivery during balloon inflation.

[0021] Figure 2 is an exploded perspective view of an advanced inflation device 1 according to an embodiment of the present invention. Figure 3 is a perspective view of the assembled device 1, showing the device 1 connected to a delivery balloon catheter 33 and an expandable prosthesis 32.

[0022] Apparatus 1 comprises a housing 14 and a barrel 37 extending from housing 14. Components 14 and 37 collectively form the overall housing of apparatus 1. However, for brevity, the term “housing” will be used primarily to refer to component 14, and the term “barrel” will be used primarily to refer to component 37.

[0023] A control plunger 2 extends from the housing 14, preferably with a handle 12 at its distal end. The housing 14 is preferably provided with a retention mechanism 10 for selectively locking and unlocking the plunger 2 in place relative to the housing 14. As shown in FIG. 3, the device 1 is configured such that a hose 4 is connectable to the device 1, such as at the proximal end of the barrel 37. As shown, the end of the hose 4 may be provided with a luer connector 28 for connection to a catheter 33, which may include a delivery balloon 31 for engaging an expandable prosthesis 32. The hose 4 is in communication with a fluid chamber 15 (identified in FIGS. 4A, 5A, 6B, 7A, 8 and 9) within the device 1 such that the device 1 may use it to inflate and deflate the delivery balloon 31.

[0024] Preferably, the device includes a pressure gauge in communication with the fluid chamber 15. The pressure gauge is provided so that a user can view the pressure gauge to determine the pressure being supplied to the delivery balloon. The pressure gauge can be a conventional screw-on pressure sensing and display module, or can be provided as an integrated pressure sensing and display module housing 35 having a mechanical or electronic pressure sensing and display module 34 protected by a lens 36, as shown in FIG.

[0025] In operation, a user holds the housing 14 and pushes the handle 12 of the plunger 2 into / towards the housing 14 to increase pressure and inflate the delivery balloon 31, or pulls the handle 12 of the plunger 2 out / away from the housing 14 to decrease pressure and deflate the delivery balloon 31. All functions of the device 1 are performed by simply moving the single control plunger 2 distally or withdrawing it proximally within the bore 3 of the barrel 37 (see FIG. 2).

[0026] As shown in FIG. 2, the plunger 2 may not be threaded along its length, and a small piston 5 is preferably provided at the end of the plunger 2 opposite the end having the handle 12. This small piston 5 may be formed integrally with the plunger 2 or may be attached to the end of the plunger 2. Preferably, the small piston 5 is provided with a piston seal 30 for sealing with the bore 11 of the large piston 7 (bore 11 is identified in FIG. 5A and the seal can be seen in FIG. 5B). A piston seal 29 is also preferably provided on the large piston 7 for sealing with the bore 3 of the barrel 37 (see FIG. 6B). In this way, the small piston 5 slides back and forth within the bore 11 of the large piston 7, and the large piston 7 slides back and forth within the bore 3 of the barrel 37, with both pistons providing a seal against their respective bores at all times.

[0027] The lock slide assembly 13 is mounted on the end of the large piston 7 within a lock chamber 25 which is preferably sealed by a lock chamber cover 22. The lock slide assembly 13 preferably includes a plunger latch 20, a latch biasing member such as a compression spring 24, and an actuator block 19.

[0028] The piston 5 also preferably provides a piston shoulder 6 as well as at least one plunger stop 8, and within the housing 14 is a bolt 16 which is driven towards the longitudinal axis of the plunger 2 by a bolt biasing member such as a compression spring 18.

[0029] As shown in Figures 5A and 5B, when the handle 12 of the plunger 2 is pulled by the user to move the control plunger 2 to a fully proximal position, the large piston 7 is drawn proximally by abutment against the piston shoulder 6 as it moves with the control plunger 2. Meanwhile, when the control plunger 2 is moved distally from this fully proximal state, the plunger latch 20 aligns with at least one plunger stop 8 of the control plunger 2, allowing it to be driven into engagement by the latch biasing member 24. This locking engagement of the control plunger 2 and the large piston 7 binds both pistons together and allows them to move distally in unison in a synchronized manner within a locking chamber 25 at the proximal end of the large piston 7, as shown in Figures 4A, 4B and 4C.

[0030] As best seen in FIG. 6A, after the large piston 7 (with piston seal 29) reaches its full distal travel limit, thereby delivering, for example, approximately 50%-80% of the fluid charge required by the delivery balloon catheter 33, the large piston 7 is locked in place within the expansion device housing 14. Locking of the large piston 7 is accomplished by the biasing bolt 16, which allows the locking slide assembly 13 to release the plunger 2 and allow the small piston 5 to continue to move to its full distal position as shown in FIG. 8. In this manner, the small piston 5 can deliver the remaining 50%-20% of fluid to complete the expansion of the stent delivery balloon with a reduced plunger force, for example, as shown by curve "B" in FIG. 1. All of the fluid displaceable within the expansion device fluid chamber 15 may then be dispensed by the user through the continuous application of a single distal force on the control plunger 2. This locking and unlocking action occurs automatically depending on the position of the control plunger 2 and the large piston 7, so no secondary user input is required to effect locking or unlocking, and therefore the locking and unlocking action between the pistons is transparent to the user.

[0031] As shown in FIGS. 7A and 7B, the bolt 16, which controls the automatic locking and unlocking of the large piston 7 from the control plunger 2, is operable within the bolt guideway 17 and is disposed at the proximal end of the bore 3 of the expander barrel 37. The bolt 16 within the bolt guideway 17 is biased toward the control plunger 2 by a bolt biasing member 18 also disposed within the bolt guideway 17. The bolt guideway 17 is oriented to allow the bolt 16 to be driven toward the central axis of the bore 3 of the expander barrel 37, and thus positioned to act on the actuator block 19 of the lock slide assembly 13 whenever the lock chamber 25 at the proximal end of the large piston 7 is aligned therewith. As shown in FIGS. 4A and 4B, the bolt 16 is blocked by the outer wall 26 of the large piston 7 and can only extend from the bolt guideway 17 after the piston outer wall 26 and the floor 27 of the lock chamber 25 have moved distally beyond it. Once unencumbered by the piston outer wall 26 and lock chamber floor 27, the bolt 16 is free to extend beyond the lock chamber floor 27, holding the piston 7 in its fully distal position. The bolt 16, residing within and aligned by the bolt guideway 17, may be guided either linearly across as shown here, or may be guided by a fixed, pivotable attachment to the housing 14, as best suits the space available within the device.

[0032] As previously mentioned, the lock slide assembly 13 preferably includes a plunger latch 20, an actuator block 19 and a latch biasing member means 24. The plunger latch 20 is biased toward the plunger 2 by the biasing member 24 so as to engage at least one plunger stop 8 of the control plunger 2. The plunger latch 20 and the actuator block 19 slidably engage with each other by a surface 21 of the actuator block 19 engaging a corresponding surface 23 of the plunger latch 20. The plunger latch 20 is lightly spring biased toward the plunger 2 by the biasing member 24. These abutment surfaces 21 and 23 allow the plunger latch 20 to be driven toward the control plunger 2 by the latch biasing member 24 whenever the actuator block 19 and bolt 16 are moved away from the control plunger 2 by a cam 9 preferably provided on the piston shoulder 6, as shown in Figures 5A, 5B and 5C. Conversely, when the biasing member 18 of the bolt 16 overcomes the force of the latch biasing member 24 of the plunger latch 20 and pushes the actuator block 19 toward the control plunger 2, the abutment surfaces 21 and 23 allow the plunger latch 20 to be driven in a direction away from the control plunger 2.

[0033] The lock slide assembly 13 remains with the large piston 7 at all times while the bolt 16 resides within the bolt guideway 17 at the proximal end of the bore 3 of the expander barrel 37. The bolt 16 is positioned within the bolt guideway 17 to align with the actuator block 19 of the lock slide assembly 13 whenever the large piston 7 reaches its distal-most position. Thus, whenever the large piston 7 reaches its distal-most position, the bolt 16 is no longer covered by the piston outer wall 26 and the lock chamber floor 27 and can therefore move towards the control plunger 2. This action of the bolt 16 locks the piston 7 in its distal-most position and releases the plunger latch 20 from engagement with at least one plunger stop 8 of the control plunger 2, as shown in Figures 6A and 6B, while driving the lock slide assembly 13 to an unlocked state with the control plunger 2, as shown in Figure 6C, by compressing the latch biasing member 24. This unlocking action releases the control plunger 2 from the large piston 7 to allow the small piston 5 to be free to be driven distally, as shown in Figures 6A and 6B, to complete the displacement of the hydraulic fluid remaining in the fluid chamber 15. Thus, continued distal movement of the control plunger 2 and movement of both pistons is controlled by an automatic lock and release mechanism that is responsive to the position of the two fluid displacement pistons within the expander housing 14. The locking mechanism also holds the large piston 7 in its full distal position within the bore 3 of the expander barrel 37, preventing it from being hydraulically displaced rearward by pressure buildup as the piston 5 continues to advance within the fluid chamber 15.

[0034] With piston control from the lock assembly 13, advancement of the smaller piston 5 within the bore 11 of the larger piston 7 to supply fluid through the luer bearing hose 4 to deliver the expandable prosthesis 32 shown in FIG. 3 occurs during the period of highest delivery force demand to expand the delivery balloon 31. Thus, deployment of the expandable prosthesis 32 can be accomplished with much less user force on the handle 12 of the control plunger 2 than would be required if a single piston of the same diameter as the larger piston 7 were utilized. Because the effective area of ​​the smaller piston 5 is smaller than the effective area of ​​both pistons (5 and 7) advanced together, the amount of force required to advance the control plunger 2 during final balloon expansion is reduced by the percentage of the effective area of ​​the larger piston 7 relative to the combined effective area of ​​both pistons (5 and 7).

[0035] After the control plunger 2 is fully advanced and hydraulic fluid is fully evacuated from the fluid chamber 15 by both pistons during inflation of the stent balloon, or alternatively, when initially filling the fluid chamber 15 with fluid from the fully evacuated position of both pistons, the control plunger 2 is withdrawn proximally, first moving the small piston 5 proximally. As the small piston 5 approaches the limit of its proximal travel in the bore 11 of the piston 7, the cam 9 on the piston shoulder 6 engages the actuator block 19, moving it away from the control plunger 2 while continuing to withdraw the control plunger 2 proximally towards the user. This movement of the actuator block 19 simultaneously pushes the bolt 16 away from the control plunger 2, disengaging it from its locking engagement with the large piston 7, thereby releasing the piston 7 to move freely proximally. As the large piston 7 moves proximally under the force of the operator on the control plunger 2, the outer wall 26 of the piston 7 blocks the movement of the bolt 16 towards the center of the control plunger 2. Both the small piston 5 and the large piston 7 can again act as one large surface area entity when the piston shoulder 6 abuts against the lock chamber floor 27. Thus, both pistons move in unison with the control plunger 2 back to the proximal travel limit of the large piston 7. This sequence of events causes hydraulic fluid to be first drawn into the small bore 11 in the large piston 7 by the small piston 5, and then loaded into the fluid chamber 15 in the bore 3 of the expander barrel 37 as the control plunger 2 continues to be withdrawn. As shown in FIG. 9, this action and sequence of events causes hydraulic fluid to be expelled from the expanded delivery balloon 31 into the fluid chamber 15 as both pistons are moved proximally.

[0036] The exact same action and sequence of events that expels hydraulic fluid from the delivery balloon 31 also facilitates the initial filling of hydraulic fluid into the fluid chamber 15 when the advanced inflation device 1 is prepared for use. Starting with both the large piston 7 and the small piston 5 in their distal-most positions, the large piston 7 is locked to the inflation device housing 14 by the bolt 16 while the small piston 5 is free to move by the plunger 2. Pulling the plunger 2 proximally first draws the small piston 5 proximally until it reaches its proximal-most position within the bore 11 of the piston 7, thereby allowing it to be initially filled with hydraulic fluid through the luer bearing hose 4 before the piston shoulder 6 engages with the lock chamber floor 27 of the large piston 7. Furthermore, as the small piston 5 approaches its proximal-most position within the bore 11 of the piston 7, the actuator block 19, controlled by the cam 9 on the piston shoulder 6, drives the bolt 16 to release the large piston 7 and withdraw it to its proximal-most position to allow a secondary filling of the remainder of the fluid chamber 15 with hydraulic fluid. The coordinated action of the small piston 5 and large piston 7 relative to one another (and controlled by the lock slide assembly 13) serves to allow for the sequential filling of each bore (11 and 3, respectively) as hydraulic fluid is drawn into the fluid chamber 15 through the luer bearing hose 4 of the device 1. This action allows both the bore 11 of the piston 7 and the bore 3 of the expansion device barrel 37 to fill the fluid chamber 15 in order of their size, thereby minimizing air entrapment within the respective bores and facilitating purging of any air bubbles that may be trapped within those bores.

[0037] With both pistons 5 and 7 in their proximal-most positions, as shown in FIG. 9, purging of entrained air or hydraulic fluid from the fluid chamber 15 can be accomplished by pushing the fully extended plunger 2 distally to drive both the small piston 5 and the large piston 7 distally, with the small piston 5 remaining locked within the bore 11 in the large piston 7 by the plunger latch 20. Once the large piston 7 reaches its distal-most position within the bore of the barrel 37, it is locked to the housing 14 by the bolt 16. As soon as the large piston 7 is locked against further movement, the small piston 5 unlocks from the large piston 7 and continues to move distally as the plunger 2 moves to its full distal position, as shown in FIG. 8. This allows any entrained air in the hydraulic fluid within the device 1 to be evacuated through the luer bearing hose 4.

[0038] During filling of the delivery balloon 31 for setting the expandable prosthesis 33, the first stage of filling, depicted by segment "1" of curve "A" in FIG. 1, is accomplished by rapid distal advancement of the large piston 7 housing the small piston 5. This advancement of both pistons 5 and 7 (controlled by user force applied to the handle 12 of the control plunger 2) rapidly displaces a large volume of fluid with a relatively low plunger force, as shown, to quickly achieve an initial, large volume filling of the delivery balloon 31. The combined swept areas of both the large piston 7 and the small piston 5 would require significant plunger force to continue filling of the delivery balloon 31, as shown by segment "2" of curve "A" in FIG. 1, without unlocking of the small piston 5. By unlocking the small piston 5 to complete filling of the delivery balloon 31, the plunger force required to complete filling of the delivery balloon 31 during final setting of the expandable prosthesis 32 can be significantly reduced, as shown by curve "B" in FIG. 1. In this manner, the user force on the plunger 2 of the device 1 required to quickly complete balloon expansion for delivery of the expandable prosthesis 32 is reduced to a more user-friendly level with the introduction of the smaller piston 5.

[0039] The respective diameters and fluid displacement volumes of both the large piston 7 and the small piston 5 can be widely adjusted to tailor their plunger force demand characteristics to best suit the inflation characteristics of a given delivery balloon 31 and respective expandable prosthesis 32.

[0040] In essence, the bolt 16 and associated biasing member 18 can be considered collectively as a first locking mechanism (i.e., a locking mechanism that locks and unlocks the piston 7 relative to the housing 14). The lock-slide assembly 13 can be considered collectively as a second locking mechanism (i.e., a locking mechanism that locks and unlocks the plunger 2 relative to the piston 7). In this manner, the first locking mechanism (i.e., the bolt 16 and associated biasing member 18) is not only a locking mechanism, but also an actuation mechanism for actuating the second locking mechanism (i.e., the lock-slide assembly 13) from a locked state to an unlocked state due to how the device 1 is configured to operate. That is, when the first locking mechanism (i.e., the bolt 16) locks, the first locking mechanism also unlocks the second locking mechanism. When the piston 7 is locked in place in the housing 14, the plunger 2 is unlocked from the piston 7. In this manner, the piston 7 is generally locked to the housing 14 or locked to the plunger 2 depending on the operational state of the device 1 (i.e., depending on the extent to which the handle 12 is pushed into or pulled out of the housing 14). Thus, the first and second locking mechanisms can be collectively considered to be a single actuator that acts to selectively lock the piston 7 to either the housing 14 or the plunger 2.

[0041] It should be understood that in order to facilitate orchestration of automatic locking or unlocking actions within the device 1, it is not necessary or possible for the piston to move in a direction opposite to the direction of movement of the user-actuated control plunger 2 in response to fluid pressure within the fluid chamber 15. During the filling phase of expansion of the delivery balloon, fluid movement from the fluid chamber 15 is always maintained and is not momentarily interrupted or absorbed by the operation of the piston or valve, and user input to the operation of the control plunger 2 is not lost in order to facilitate operation of the device. Any depressurization of the fluid chamber 15 must be initiated by a deliberate change in the user's force on the control plunger 2. Furthermore, operation of the switching mechanism controlling the movement of either piston within the advanced expansion device 1 is strictly dependent on the position of the large piston 7 and the small piston 5 relative to the bore 3 of the expansion device barrel 37. To ensure predictability and consistency in performance of the device 1, the locking slide assembly 13 which synchronizes the piston movement is designed to operate without requiring or relying on any fluid pressure dependency, or mechanically actuated valve means, or elastic deflection of parts responsive to fluid pressure, or frictional engagement of locking mechanisms.

[0042] While particular embodiments of the present invention have been shown and described, it is anticipated that those skilled in the art could devise various modifications thereto without departing from the spirit and scope of the invention.

Claims

1. Fluid movement and pressure device Housing and a first piston within the housing; a plunger extending from the housing and having a second piston thereon; an actuator that selectively locks the first piston relative to the housing when the second piston is in a first position within the fluid displacement and pressure application device and selectively locks the first piston relative to the plunger when the second piston is in a second position within the fluid displacement and pressure application device; 1. A fluid movement and pressurization device comprising:

2. 2. The fluid movement and pressurization device of claim 1, wherein the actuator comprises a first locking mechanism that locks and unlocks the first piston relative to the housing, and a second locking mechanism that locks and unlocks the plunger relative to the first piston.

3. 3. The fluid movement and pressurization device of claim 2, wherein the first locking mechanism comprises an actuation mechanism for actuating the second locking mechanism.

4. The fluid movement and pressurization device of claim 1 , further comprising a retention mechanism on the housing configured to selectively lock and unlock the plunger in a predetermined position relative to the housing.

5. 10. The fluid transfer and pressurization device of claim 1, wherein the plunger is threadless.

6. 2. The fluid movement and pressurization device of claim 1, further comprising a barrel having a bore, wherein the first piston has the bore, the plunger has a handle thereon, the handle being at an end of the plunger opposite a second piston on the plunger, the first piston having a first piston seal, the second piston having a second piston seal, the first piston seal sealing with the bore of the barrel, the second piston seal sealing with the bore of the first piston, the second piston sliding back and forth within the bore of the first piston, and the first piston sliding back and forth within the bore of the barrel.

7. 7. The fluid movement and pressurization device of claim 6, wherein the actuator comprises a locking slide assembly having a plunger latch, a latch biasing member, and an actuator block.

8. 8. The fluid displacement and pressurization device of claim 7, wherein the plunger provides a piston shoulder and at least one plunger stop, and within the housing is a bolt that is driven toward the longitudinal axis of the plunger by a bolt biasing member.

9. 9. The fluid transfer and pressurization device of claim 8, wherein when the handle of the plunger is pulled by a user to move the plunger to a fully proximal position, the first piston is withdrawn proximally by its contact against the piston shoulder provided by the plunger, and once the plunger is moved distally from the fully proximal position, the plunger latch aligns with the at least one plunger stop of the plunger, allowing the plunger latch to be driven into engagement by the latch biasing member, and the locking engagement of the plunger and the first piston binds both the first and second pistons together and allows them to move distally as a unit in synchronization.

10. 10. The fluid transfer and pressurization device of claim 9, wherein the first piston is locked in place within the housing when the first piston reaches its full distal travel limit, the locking of the first piston being effected by the bolt, which allows the locking slide assembly to release the plunger and allow the second piston to continue moving to its full distal position.

11. 11. The fluid movement and pressurization device of claim 10, wherein a bolt controlling the automatic locking and unlocking of the first piston from the plunger is actuable within a bolt guideway and is located at a proximal end of the bore of the barrel, the bolt within the bolt guideway being biased toward the plunger by the bolt biasing member located within the bolt guideway, the bolt guideway being oriented to allow the bolt to be driven toward a central axis of the bore of the barrel, thereby positioning the bolt to act on the actuator block of the locking slide assembly whenever a locking chamber in a proximal end of the first piston is aligned with the bolt.

12. 12. The fluid movement and pressurization device of claim 11, wherein the bolt is obstructed by an outer piston wall of the first piston and is only permitted to extend from the bolt guideway after the outer piston wall and a lock chamber floor of the lock chamber have moved distally past the bolt, and once the bolt is no longer obstructed by the outer piston wall and the lock chamber floor, the bolt is free to extend beyond the lock chamber floor and hold the first piston in its fully distal position.

13. 8. The fluid movement and pressurization device of claim 7, wherein the plunger latch is biased toward the plunger by the latch biasing member so as to engage the at least one plunger stop of the plunger.

14. 14. The fluid movement and pressurization device of claim 13, wherein the plunger latch and the actuator block are slidably engaged with one another by a surface of the actuator block engaging a corresponding surface of the plunger latch, and the plunger latch is biased by the latch biasing member to bias the plunger latch toward the plunger.

15. 15. The fluid movement and pressurization device of claim 14, wherein the surface enables the plunger latch to be driven toward the plunger by the latch biasing member whenever the actuator block and bolt are moved away from the plunger.

16. A fluid movement and pressurization device as described in claim 15, wherein a cam is provided on the piston shoulder, said cam moving said actuator block and said bolt away from said plunger.

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