CN113018545B - Flow guiding adjusting device - Google Patents

Abstract

The invention relates to the technical field of fluid control, in particular to a diversion regulating device. The device comprises a conduit and an adjustment assembly, the conduit comprises a pipe wall, a channel defined by the pipe wall, and a side hole opened on the pipe wall, one end of the channel is an inlet, the other end is an outlet, the side hole communicates with the channel and is located between the inlet and the outlet between; the adjustment assembly includes a gas source, a balloon and a trachea, the balloon is arranged in the channel and between the outlet and the side hole, the gas source is connected to the balloon through the trachea, and is used to inflate or exhaust the balloon; The balloon is inflated after inflation to at least partially obstruct the passage and increase the amount of fluid expelled through the side orifice, and the balloon deflates after deflation to reduce obstruction of the passage and increase the amount of fluid expelled through the outlet. The present invention can adjust the flow direction and flow rate of the fluid in the catheter by changing the state of the balloon.

Description

Diversion adjustment device

technical field

The present disclosure relates to the technical field of fluid control, and in particular, to a diversion regulating device.

Background technique

Extracorporeal cardiopulmonary support (extracorporeal membrane oxygenation, ECMO) is a percutaneous implantable mechanical circulatory assistance technology. The extracorporeal cardiopulmonary support device usually consists of three parts: the main engine, the pump head and the membrane oxygenator. The host controls and monitors the operation of the extracorporeal cardiopulmonary support device, the pump head is used to circulate the blood inside and outside the body, and the membrane oxygenator is used to provide oxygen and exchange carbon dioxide in the blood discharged from the body. The extracorporeal cardiopulmonary support device mainly drains the venous blood in the patient to the outside, and the blood is returned to the patient after oxygenating and removing carbon dioxide in the blood through the membrane oxygenator. According to the different ways of blood return, extracorporeal cardiopulmonary support devices mainly have two forms: venovenous ECMO (VV-ECMO) and venous-arterial ECMO (VA-ECMO), the former only has respiratory assistance. , while the latter has both circulatory and respiratory assistance.

For patients with acute heart failure, the main problem is the lack of blood supply and oxygen supply to major organs including the heart, and due to insufficient oxygen supply to the heart itself, the cardiac output is further reduced, which further aggravates the symptoms, and eventually leads to the death of the patient due to heart failure. . At present, VA-ECMO (femoral arteriovenous cannulation) and IABP (Intra-Aortic Balloon Pump Therapy, aortic balloon counterpulsation) are usually used clinically for life support and improvement of heart failure. But this approach has several major flaws:

(1) The oxygenated blood flow with high oxygen content returned by the femoral artery is far away from the coronary inlet, which does not help to improve the blood oxygenation near the coronary inlet, so it cannot improve the insufficient oxygen supply to the heart. Also, because of the presence of the IABP balloon, it is not possible to deliver high-oxygen blood to the heart by cannulating the subclavian artery or other arterial circuit closer to the coronary entrance.

(2) Due to the existence of defect (1), when the patient's own lung function is defective and causes insufficient oxygenation, the blood squeezed into the coronary artery by the IABP balloon is also blood with lower oxygen content, although it increases the blood supply to the heart. , but does not help fundamentally alleviate the problem of insufficient oxygen supply to the heart, and cannot or is insufficient to correct the development of heart failure.

(3) The IABP balloon greatly disturbs the aortic blood flow, which is likely to cause poor perfusion of organs (liver, kidney), etc., resulting in complications and unfavorable patient prognosis.

It can be seen that there is no solution in the related art to effectively solve or improve the problem of insufficient oxygen supply to the heart itself.

SUMMARY OF THE INVENTION

In view of the defects of the prior art, the purpose of the present disclosure is to provide a diversion adjustment device, which can adjust the flow direction and flow rate of the fluid in the catheter by changing the state of the balloon. When the present disclosure is used for extracorporeal cardiopulmonary support, the blood flow direction and/or flow rate in the catheter can be changed according to clinical needs, the blood volume perfused to the coronary artery and the content of blood oxygen in the blood can be increased, and the problem of insufficient oxygen supply to the heart itself can be improved or solved. question.

The present disclosure provides a flow regulation device, comprising a catheter for guiding blood in extracorporeal cardiopulmonary support, and an adjustment assembly for regulating the flow direction and/or flow of blood in the catheter ;in,

The conduit includes a pipe wall, a channel defined by the pipe wall, and a side hole opened on the pipe wall, one end of the channel is an inlet, the other end is an outlet, the side hole communicates with the channel and is located at the between said inlet and said outlet;

The adjustment assembly includes a gas source, a balloon and a trachea, the balloon is disposed in the channel and between the outlet and the side hole, the gas source is connected to the balloon through the trachea , used to inflate or deflate the balloon; the balloon is inflated after inflation to at least partially block the passage, increasing the amount of fluid expelled through the side hole, the balloon being deflated Post-contraction to reduce blockage of the channel and increase the amount of fluid expelled through the outlet.

In the present disclosure, side holes are provided on the tube wall of the catheter, an inflatable balloon is inserted into the catheter, and the balloon is inflated or degassed by an external air source to flexibly adjust the flow direction and flow of the fluid in the catheter. Specifically, when the external air source inflates the balloon, the balloon gradually expands to block the channel at least partially. At this time, the fluid cannot be smoothly discharged from the channel outlet, and the fluid accumulated between the channel inlet and the balloon exerts a force on the tube wall. The pressure increases, forcing the fluid out of the side hole; when the balloon deflates and deflates, the resistance of the balloon to the fluid decreases, and the fluid is more easily expelled from the channel outlet, thereby reducing the amount of fluid expelled from the side hole.

When the diversion regulating device of the present disclosure is used for blood perfusion, the direction of blood flow can be changed according to clinical needs, so as to implement perfusion of organs in different directions. Specifically, when the adjusting device of the present disclosure is used for extracorporeal cardiopulmonary support, the side hole of the catheter can be placed near the entrance of the coronary artery of the heart. The hole shoots in the direction of the coronary inlet, increasing the blood pressure, blood flow and blood oxygen content at the coronary inlet; the balloon is deflated at the time outside the cardiac ejection cycle, so that most of the blood flow flows out in the direction of the channel outlet, increasing the pressure on the outside of the heart. Perfusion of organs other than the heart, thereby improving or solving the problem of insufficient oxygen supply to the heart itself.

Description of drawings

In order to illustrate the technical solutions of the present disclosure more clearly, the following briefly introduces the accompanying drawings that are required to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a diversion adjustment device in a balloon deflated state provided by an embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of a diversion adjustment device in a balloon inflation state provided by an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of a blood flow direction in a deflated state of a balloon provided by an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of a blood flow direction in a balloon inflation state provided by an embodiment of the present disclosure;

FIG. 5 is a schematic structural diagram of a diversion adjustment device in a balloon deflated state provided by an embodiment of the present disclosure;

FIG. 6 is a schematic structural diagram of a diversion adjustment device in a balloon inflation state provided by an embodiment of the present disclosure;

FIG. 7 is a schematic diagram of a blood flow direction in a state where the balloon is deflated according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of the blood flow direction of the balloon in an inflated state provided by an embodiment of the present disclosure.

In the figure: 1-catheter, 2-adjustment assembly; 11-tube wall, 12-channel, 13-side hole, 14-outlet, 15-inlet; 21-balloon, 22-trachea, 23-first air source, 24-First valve, 25-Second air source, 26-Second valve, 27-Valve plate; 3-Subclavian artery, 4-Coronary artery.

Detailed ways

In order to make those skilled in the art better understand the solutions of the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only Embodiments are part of the present disclosure, but not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present disclosure.

It should be noted that the terms "first", "second" and the like in the description, claims and drawings of the present disclosure are used to distinguish similar objects, and are not necessarily used to describe a specific sequence or sequence. It is to be understood that the data so used may be interchanged under appropriate circumstances such that the embodiments of the disclosure described herein can be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having", and any variations thereof, are intended to cover non-exclusive inclusion.

The main problem of patients with acute heart failure is the lack of blood supply and oxygen supply to various organs including the heart. Although the current clinical method of VA-ECMO combined with IABP can solve the problem of blood supply to the heart, it cannot improve the problem of oxygen supply to the heart.

The key to improving the oxygen supply of the heart is to introduce the blood with high oxygen content into the coronary arteries. The oxygen content of the blood that has undergone extracorporeal oxygenation is higher than that of the arterial blood. Can improve oxygen supply to the heart. However, at present, when blood cannula is returning blood flow, the flow rate of blood flow is determined by the power source such as the external blood pump and the pressure flow resistance, and the blood flow direction is determined by the position of the cannula and the opening of the cannula, which cannot change the blood flow during the blood delivery. direction of flow. That is, existing cannulas cannot meet the need for infusion of high oxygen content blood close to the coronary arteries. To this end, the embodiments of the present disclosure provide a flow regulation device, which can change the flow direction of oxygenated blood in the human body, so as to increase the blood oxygen supply to the coronary arteries during cardiac ejection, and to increase the blood oxygen supply to the coronary arteries outside the cardiac ejection. The effect of blood oxygen supply to other organs, simulating the blood pressure and blood flow pulsation generated by the heartbeat, improve or eliminate the problem of cardiac hypoxia.

Fig. 1 shows a diversion adjustment device provided by an embodiment of the present disclosure, please refer to Fig. 1 , the device includes a conduit 1 and an adjustment assembly 2, the conduit 1 is a hose, and is used for guiding fluid, and the adjustment assembly 2 is used for The flow direction and/or flow rate of the fluid in the conduit 1 is adjusted. Specifically, when the device of the present disclosure is applied to extracorporeal cardiopulmonary support, it may be a part of the extracorporeal cardiopulmonary support device. In this case, the catheter is used to guide the oxygenated blood, and the regulating component is used to regulate the oxygenated blood in the The flow direction and/or flow in the human body.

Referring to FIG. 1 , the conduit 1 may include a pipe wall 11 , a channel 12 defined by the pipe wall 11 , and a side hole 13 opened on the pipe wall 11 , one end of the channel 12 is an inlet 15 , the other end is an outlet 14 , and the side hole 13 It communicates with the channel 12 and is located between the inlet 15 and the outlet 14 . In a feasible implementation manner, the side holes 13 can be strip-shaped holes arranged along the length of the conduit 1 to minimize the influence of the side holes 13 on the cross-section of the channel 12 and ensure that the fluid flows from the inlet 15 to the outlet 14 during the process , the leakage to the side hole 13 is as little as possible.

The adjustment assembly 2 may include a gas source, a balloon 21 and a trachea 22, the balloon 21 is arranged in the channel 12 and is located between the outlet 14 and the side hole 13; 21 is inflated or deflated; balloon 21 is inflated after inflation to at least partially block passage 12, increasing the amount of fluid expelled through side hole 13, and balloon 21 is deflated after deflation to reduce obstruction of passage 12 , increasing the amount of fluid discharged through outlet 14 .

In a feasible implementation manner, the air source includes a first air source 23 and a second air source 25 , the first air source 23 is used to inflate the balloon 21 , and the second air source 25 is used to exhaust the balloon 21 Specifically, the first gas source 23 may be a high-pressure gas source, the second gas source 25 may be a negative pressure gas source or the atmosphere, and both the first gas source 23 and the second gas source 25 are provided outside the channel 12 . One end of the trachea 22 is connected to the balloon 21, and the other end is a branch pipeline. The branch pipeline includes a first branch pipe and a second branch pipe. The first branch pipe is connected to the first gas source 23, and the second branch pipe is connected to the second gas source. Source 25 is connected. The first branch pipe is provided with a first valve 24, the second branch pipe is provided with a second valve 26, the first valve 24 is used to connect/close the gas delivery between the first gas source 23 and the balloon 21, and the second valve 26 It is used to connect/close the gas delivery between the second gas source 25 and the balloon 21 . When inflating, the balloon can be inflated through an external high-pressure air source by opening the valve connecting the balloon to the high-pressure air source. When deflated, the valve connecting the balloon to the atmosphere can be opened. Due to the contraction force of the balloon itself, the gas in it will be quickly discharged into the atmosphere, or the exhaust port of the second branch pipe can be connected to the negative pressure source to accelerate the exhaust. .

In the embodiment of the present disclosure, the flow direction of the fluid is associated with the state of the balloon, and the flow direction of the fluid in the catheter can be adjusted by changing the state of the balloon. details as follows:

Close the first valve 24, block the communication between the first air source 23 and the balloon 21, open the second valve 26, make the second air source 25 communicate with the balloon 21, or close the first air source 21 after the balloon 21 is deflated. The valve 24 makes the balloon 21 in a contracted state, as shown in FIG. 1 , at this time, the balloon 21 hardly blocks the channel 12, and the resistance in the channel 12 is much smaller than the resistance of the tube wall 11, so the fluid entering the channel 12 Most of the fluid will flow out through the outlet 14 , and a small amount of fluid or even no fluid will flow out from the side hole 13 . Close the second valve 26, block the communication between the second air source 25 and the balloon 21, open the first valve 24, conduct the first air source 23 and the balloon 21, and drive the first air source 23 to inflate the balloon 21 , the balloon 21 inflates after inflation, blocking the channel 12 between the inlet 15 and the outlet 14 , forcing the fluid that could originally flow out from the outlet 14 to be discharged from the side hole 13 instead. In practical applications, the degree of obstruction of the channel 12 by the balloon 21 can be adjusted by controlling the amount of inflation. When the balloon 21 does not completely block the channel 12, the fluid can flow out from the side hole 13 and the outlet 14 at the same time. When the channel 12 is used, the fluid can only flow out from the side hole 13 .

The adjusting device provided by the embodiments of the present disclosure can be used for extracorporeal cardiopulmonary support to dynamically adjust the direction and amount of blood perfusion, thereby improving or solving the problem of insufficient oxygen supply to the heart itself. Figures 3 and 4 are application scenarios of the adjusting device provided by the present disclosure. Please refer to Figure 3. One end of the catheter 1 is connected to ECMO outside the body, and the other end of the catheter 1 is inserted from the subclavian artery 3, and enters other In the aorta, the side hole 13 of the catheter 1 is placed near the entrance of the coronary artery 4 of the heart, and the blood after extracorporeal oxygenation is introduced into the channel 12 through the entrance 15, and the ejection cycle of the heart is obtained by monitoring the monitoring equipment. , the balloon 21 is inflated, so that the oxygenated blood is ejected from the side hole 13 to the inlet direction of the coronary artery 4 (as shown in FIG. 4 ), and the blood pressure, blood flow and blood oxygen content at the inlet of the coronary artery 4 are increased; The balloon 21 is deflated at times other than the cardiac ejection cycle, so that most of the blood flow flows out in the direction of the channel outlet 14 (as shown in FIG. 3 ), increasing the perfusion to other organs except the heart.

Both FIGS. 3 and 4 are intubated through the subclavian artery 3 , but the device provided by the embodiment of the present disclosure can be used for intubation in other locations and when the blood flow direction needs to be changed.

Fig. 5 shows another flow diversion adjustment device provided by an embodiment of the present disclosure, please refer to Fig. 5 , the device includes a conduit 1 and an adjustment assembly 2, the conduit 1 is a hose, and is used for guiding fluid, and the adjustment assembly 2 is used for It is used to adjust the flow direction and/or flow rate of the fluid in the conduit 1 . Specifically, when the device of the present disclosure is applied to extracorporeal cardiopulmonary support assistance, it may belong to a part of the extracorporeal cardiopulmonary support assistance device. The direction and/or flow of blood in the body.

The conduit 1 may include a pipe wall 11, a channel 12 defined by the pipe wall 11, a side hole 13 opened on the pipe wall 11, and a valve plate 27 disposed near the side hole 13. One end of the channel 12 is an inlet 15, and the other end is a valve plate 27. At the outlet 14, the side hole 13 communicates with the channel 12 and is located between the inlet 15 and the outlet 14. One side of the valve plate 27 is connected to the edge of the side hole 13, and the other side of the valve plate 27 is the active side.

The adjustment assembly 2 includes an air source, a balloon 21 and a trachea 22. The balloon 21 is arranged in the channel 12 and is located between the outlet 14 and the side hole 13; Inflate or vent. The air source includes a first air source 23 for inflating the balloon 21 and a second air source 25 for exhausting the balloon 21. Specifically, the first air source 23 may be a high-pressure air source, The second gas source 25 may be a negative pressure gas source or the atmosphere. One end of the trachea 22 is connected to the balloon 21, and the other end is a branch pipeline. The branch pipeline includes a first branch pipe and a second branch pipe. The first branch pipe is connected to the first gas source 23, and the second branch pipe is connected to the second gas source. The sources 25 are connected, and both the first gas source 23 and the second gas source 25 are arranged outside the channel 12 . A first valve 24 is arranged on the first branch pipe, a second valve 26 is arranged on the second branch pipe, the first valve 24 is used to connect/close the gas delivery between the first gas source 23 and the balloon 21, and the second valve 26 It is used to connect/close the gas delivery between the second gas source 25 and the balloon 21 . It should be noted that the trachea can be arranged along the inner or outer wall of the catheter. Of course, a tracheal channel can also be opened on the tube wall of the catheter, and the catheter can be inserted into the channel of the catheter from the tracheal channel, so that the inner wall of the catheter can be made smoother and minimized. Obstruction of the fluid in the channel by the small trachea.

In a feasible implementation manner, the valve plate 27 is connected to the edge of the side hole 13 through an elastic member. When the balloon 21 is inflated, the inflated balloon 21 blocks the channel 12, preventing the fluid from being discharged from the outlet 14, and the pressure exerted by the fluid accumulated in the channel 12 on the tube wall 11 increases. When the pressure is greater than the supporting force of the elastic member At this time, the movable side of the valve plate is deflected away from the side hole 13 , and the fluid in the channel 12 is discharged from the side hole 13 . When the balloon 21 is deflated and contracted, the obstruction in the channel 12 is gradually eliminated, and the fluid can be discharged from the outlet 14 smoothly, so that the pressure of the fluid on the pipe wall 11 is reduced, and the pressure exerted on the valve plate is also reduced. When the pressure on the valve plate is less than the supporting force of the elastic member, the elastic member drives the movable side of the valve plate to block the side hole 13 and restore its initial position to achieve the effect of automatic reset.

In a feasible implementation manner, the movable side of the valve plate is connected to a traction cable, and the traction cable extends toward the inlet 15 of the channel 12 . When the traction cable is in a slack state, the active side of the valve plate is deflected away from the side hole 13, thereby opening the side hole 13 and allowing fluid to flow out of the side hole 13. When the traction cable is in a tightened state, the active side of the valve plate It is close to the side hole 13 so as to block the side hole 13 and prevent the fluid from flowing out of the side hole 13 . Specifically, when the balloon 21 is inflated and inflated, the valve plate can be controlled by the traction cable to open, so that the fluid in the channel 12 can be discharged through the side hole 13, and when the balloon 21 is deflated and contracted, the valve plate can be controlled by the traction cable to close, so that the The fluid in the channel 12 is discharged from the outlet 14 .

Further, the shape and size of the valve plate are matched with the side hole 13. When the valve plate blocks the side hole 13, the outer wall of the valve plate is flush with the outer wall of the catheter 1, so as to avoid hooking the vascular tissue when the catheter is pulled out.

7 and 8 are schematic diagrams of states when the adjusting device according to the embodiment of the present disclosure is used for extracorporeal cardiopulmonary support. Please refer to FIG. 7 , the inlet 15 of the catheter 1 is connected to ECMO, the side hole 13 of the catheter 1 is placed near the inlet of the coronary artery 4 of the heart, and the blood after extracorporeal oxygenation is injected into the catheter channel 12 through the inlet 15, and contracts outside the cardiac ejection cycle. The balloon 21 is closed, and the valve plate is closed, and most of the blood flow will flow out along the direction of the channel outlet 14 to perfuse other organs except the heart. Referring to FIG. 8 , when the heart is ejecting blood, the balloon 21 is inflated, and the valve plate is opened, the oxygenated blood will be ejected from the side hole 13 to the entrance of the coronary artery 4, increasing the blood pressure and blood pressure at the entrance of the coronary artery. flow and blood oxygenation.

In the embodiment of the present disclosure, when the side hole of the catheter is placed near the entrance of the coronary artery of the heart, the blood flow can be output by pulsating synchronously with the heart, so that the perfusion volume to the coronary artery and the content of blood oxygen in the perfused blood can be increased. By synchronizing blood ejection with the heart, it can simulate the blood pressure and blood flow pulsation generated by the heart beat, and improve the blood perfusion effect of downstream organs (liver, kidney, etc.). In addition, a valve plate is arranged on the edge of the side hole, and the opening and closing of the valve plate is controlled according to the state of the balloon. When the valve plate is in the closed state, it can guide the blood to flow out to the outlet. The blood that emerges from the side hole directly flushes the aortic wall causing dissection.

The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features It is considered to be the range described in this specification.

The above embodiments only represent several embodiments of the present disclosure, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the scope of the invention patent. It should be noted that, for those skilled in the art, without departing from the concept of the present disclosure, several modifications and improvements can be made, which all belong to the protection scope of the present disclosure. Accordingly, the scope of protection of the present disclosure should be determined by the appended claims.

Claims (10)

1. A kind of flow guide adjusting device, characterized by: the flow guide adjusting device is used for assisting in vitro cardiopulmonary support to dynamically adjust the blood perfusion direction and perfusion amount, and comprises a catheter and an adjusting component, wherein the catheter is used for guiding fluid, and the adjusting component is used for adjusting the flow direction and/or flow of the fluid in the catheter; the catheter comprises a catheter wall, a channel defined by the catheter wall and a side hole formed in the catheter wall, wherein one end of the channel is an inlet, the other end of the channel is an outlet, and the side hole is communicated with the channel and is positioned between the inlet and the outlet; the adjusting assembly comprises a gas source, a balloon and a gas pipe, the balloon is arranged in the channel and positioned between the outlet and the side hole, and the gas source is connected with the balloon through the gas pipe and used for inflating or exhausting the balloon; the balloon is inflated after inflation to at least partially occlude the passageway and increase the amount of fluid discharged through the side aperture, and deflated after deflation to reduce occlusion of the passageway and increase the amount of fluid discharged through the outlet.

2. The apparatus of claim 1, wherein the gas source is disposed outside of the channel.

3. The apparatus of claim 2, wherein the gas source comprises a first gas source for inflating the balloon and a second gas source for deflating the balloon.

4. The apparatus of claim 3, wherein the first gas source is a high pressure gas source; the second air source is a negative pressure air source or atmosphere.

5. The device of claim 3, wherein the trachea has one end connected to the balloon and another end comprising a branch line, the branch line comprising a first branch line and a second branch line, the first branch line connected to the first gas source and the second branch line connected to the second gas source.

6. The apparatus of claim 5, wherein the first branch is provided with a first valve and the second branch is provided with a second valve.

7. The device of claim 1, further comprising a valve plate, one side of the valve plate being attached to the periphery of the side opening and the other side of the valve plate being a movable side, wherein the movable side of the valve plate is proximate to the side opening when the balloon is in the deflated state and the movable side of the valve plate is deflected away from the side opening when the balloon is in the inflated state.

8. The apparatus of claim 7, wherein the valve plate is shaped and sized to match the side opening.

9. The device of claim 7, wherein the valve plate is connected to the edge of the side opening by an elastic member; the movable side of the valve plate can deflect away from the side hole under the condition that the balloon is inflated; under the condition that the saccule contracts, the elastic part can drive the movable side of the valve plate to be close to the side hole.

10. The apparatus of claim 7, wherein the movable side of the valve plate is attached to a pull cable that extends toward the entrance of the passageway, wherein the movable side of the valve plate is deflected away from the side opening when the pull cable is in a relaxed state, and wherein the movable side of the valve plate is proximate the side opening when the pull cable is in a tightened state.

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