The subject matter of the invention is a two-step inflator with excess protection, especially for angioplasty procedures using biodegradable stents.

Application US2020100798A1 discloses a device, system and method for inflation. The inflation device includes a housing, a compressed gas canister disposed therein, a syringe disposed within the housing, a plunger slidably disposed in the syringe having an unloaded position and a loaded position relative to the syringe, a puncture mechanism disposed within in the housing and configured to open a fluid path between the compressed gas canister and the syringe, and a positive pressure mechanism disposed within the housing and operably coupled to the syringe. Engagement of the puncture mechanism puts the syringe into fluid communication with the compressed gas canister such that gas contained therein loads into the syringe and the plunger moves from the unloaded position and the loaded position. The positive pressure mechanism is configured to maintain the gas within the syringe at a positive pressure relative to ambient pressure in order to prevent air from entering the syringe after loading.

Application US2013261601A1 discloses an inflation-deflation device that inflates a balloon with controlled pressure. Moving a large plunger provides incremental pressure increases within a syringe. A releasable latch moves a second plunger, positioned within a syringe formed by an inner columnar opening in the large plunger, between an occlusion position and a perfusion position. A three-position switch has a release position to allow the large plunger to move freely, an adjust position to provide the incremental pressure increases, and a lock position to lock the location of the plunger. Pressures at which various balloons achieve or nearly achieve a substantially circular cross-section may be extrapolated by inflating balloons with pressures equal and/or greater than the first occlusion pressure. Balloons may be pre-inflated up to or below the first occlusion pressure to achieve a substantially circular cross-section, prior to increasing the balloon to an occlusion pressure.

Prior art inflators are used for angioplasty procedures with metal stents that require significantly higher operating pressures and are less sensitive to deviations from nominal pressure. For angioplasty procedures using biodegradable stents, applying precise pressure and slowly reaching the nominal value are required. Such conditions being ensured guarantee proper stent implantation and its structural integrity and also result in no damage to the stent and the intended effects being achieved.

It is an object of the present invention to provide a device for precise pressure application during angioplasty procedures using biodegradable stents.

The two-step inflator with excess protection according to the invention comprises a housing and a cylinder secured therein, with an outlet terminating the cylinder in the lower part, with a plunger slidably mounted inside the cylinder and attached to an inner screw, the screw terminated with a handle, wherein the thread of the inner screw engages the inner thread of an outer screw and the outer screw is connected to the handle, with the inflator also comprising a pressure gauge, characterized in that the outer screw is mounted in the lining of a release brake, the lining connected to a brake release system, while connectors are movably mounted at the outer edges of the lower handle and the connectors connect in the lower position to the housing and prevent the outer screw from moving relative to the housing, and the connectors connect in the upper position to the upper handle of the inner screw and lock the outer screw and the inner screw relative to each other but enable the outer screw and the inner screw to simultaneously move relative to the housing, and further, in the lower part of the cylinder, the inflator comprises a distributor, with a pressure gauge and an adjustable excess valve attached to the distributor.

Preferably, the connectors have semicircular, opposite recesses at the ends of side edges.

Preferably, there are hollows in the upper corners of the housing, with pins mounted in the hollows.

Also preferably, pins are mounted at the edges of the upper handle. Also preferably, the housing is a two-piece housing.

The two-step inflator with excess protection according to the invention utilizes a pressure application mechanism in the form of a two-piece screw piston rod. It enables a two-step pressure application, and the adjustable excess valve attached to the inflator protects the system against exceeding the set value of pressure, and in the case of higher pressure values, redirects the excess liquid in the system to the excess container, thus reducing the pressure.

The subject matter of the invention is shown in the embodiment in the drawing, wherein Fig. 1 shows the two-step inflator with excess protection in a side view, Fig. 2 shows a cross-section of the two-step inflator along B-B line from Fig. 1, Fig. 3 shows the two-step inflator in the first step of operation in a top view, Fig. 4 shows the two- step inflator in the second step of operation in a top view, Fig. 5 shows the two-step inflator in the first step of operation in a perspective view.

The two-step inflator in an exemplary embodiment comprises a housing 6 and a cylinder 10 secured therein, with an outlet 13 terminating the cylinder in the lower part, with a plunger 9 slidably mounted inside the cylinder and attached to an inner screw 2, the screw terminated with an upper handle 1, and the thread of the inner screw 2 engages the inner thread of an outer screw 5, wherein the outer screw 5 is connected to a lower handle 3. The outer screw 5 has a coarse thread on its outer surface and a pass through opening inside, which has an inner fine thread over the entire length of its surface. The inner screw 2 has a fine thread on its outer surface, the fine thread having the same pitch as the inner thread of the outer screw 5. The upper handle 1 and the lower handle 3 make it possible to manually apply pressure by turning the screws and to act on the plunger 9 through said screws, where the plunger, by shifting in the cylinder 10, exerts pressure on the liquid contained in the cylinder. Connectors 4 are movably mounted at the outer edges of the lower handle 3 and, in the lower position, the connectors connect to the housing 6 and prevent the outer screw 5 from moving relative to the housing 6. The connection is made by the semicircular recesses in the connectors 4 engaging the pins mounted in the hollows of the housing 6. In contrast, in the upper position, the connectors 4 connect to the upper handle 1 of the inner screw 2. The connection is made by the semicircular recesses in the connectors 4, these connectors located opposite the recesses for the lower position, engaging the pins mounted at the edges of the upper handle 1. The outer screw 5 and the inner screw 2 become locked relative to each other but the outer screw 5 and the inner screw 2 are enabled to simultaneously move relative to the housing 6. The use of the lock acting on the double screw makes it necessary to apply pressure in steps. In the lower part of the cylinder 10 there is an outlet 13 and an installation opening, to which a distributor 14 is attached. A pressure gauge 11 and an adjustable excess valve 12 are connected to the distributor. For emergency situations, a quick backward shift of the screws 2, 5 relative to cylinder 10 is possible with the use of the brake system. The outer screw 5 is mounted in the lining of the release brake 7, the lining connected to the brake release system 8, the clamps of which are disposed on the sides of the housing 6. Pressing the clamps lifts the linings of the release brake 7 and enables quick backward shift to immediately reduce the pressure of the liquid in the cylinder 10.

The operation of the two-step inflator consists of two steps. In the first step, with the connectors 4 in the lower position, by shifting the inner screw 2, it is possible to precisely apply pressure to the value of about 4 atmospheres (approx. 400 kPa). The use of a fine thread ensures low speed of the shift and extended time to reach the limit value of the liquid pressure. With the set value reached for pressure, it is impossible to increase it further without changing the position of the connectors 4 and adjusting the adjustable excess valve 12. Moving the connectors 4 from the lower to the upper position makes it possible to further apply pressure through the unlocked outer screw 5 with the coarse thread. In this step, the pressure increases proportionally to the shift of said screw until it reaches the set value. In the second step, higher pressure values of about 15 atmospheres can be reached. The adjustable excess valve 12 connected to the inflator enables limit pressure ranges to be planned in each step of the inflator operation, the values of which may not be exceeded. This makes it possible to determine pressure ranges in reaching the desired value according to a planned schedule that also includes time intervals. The adjustable excess valve 12 further protects the biodegradable stent against overload. It reduces excess pressure by reducing the liquid in the system, redirecting it to the excess tank 15 (not shown). List of reference signs:

1. Upper handle

2. Inner screw

3. Lower handle

4. Connector

5. Outer screw

6. Housing

7. Linings of the release brake

8. Brake release system

9. Plunger

10. Cylinder

11. Pressure gauge

12. Adjustable excess valve

13. Outlet

14. Distributor

15. Excess tank