A transfemoral dual path reverse flow protection device

Abstract

This invention discloses a dual-pathway reflux protection device via the femoral artery, comprising: a balloon catheter; the balloon catheter extending into a first target area via the femoral artery; one side of the balloon catheter connected to a first circuit and a second circuit via a Y-connector, and a reflux pump connected between the first circuit and the second circuit; the other ends of the first circuit and the second circuit connected to a venous sheath extending into the second target area; the reflux pump activates, switching the protection device from a first state to a second state; in the first state, blood enters the first chamber of the reflux pump from the balloon catheter and the first circuit, and blood in the second chamber of the reflux pump enters the second target area via the second circuit and the venous sheath; in the second state, blood enters the second chamber of the reflux pump from the second circuit, and blood in the first chamber enters the second target area via the first circuit and the venous sheath; ensuring sufficient pressure differential and effective reflux to prevent plaque from detaching from the stenotic lesion and causing embolism in intracranial blood vessels.

Description

Technical Field

[0001] This invention relates to the field of medical devices, and more particularly to a dual-path backflow protection device via the femoral artery. Background Technology

[0002] Carotid artery stenosis is a type of ischemic stroke. The main causes of carotid artery stenosis include atherosclerosis, takayasu arteritis, and fibromuscular dysplasia. Surgical treatment for carotid artery stenosis includes two procedures: endarterectomy (CEA) and carotid artery stenting (CAS). Carotid endarterectomy involves exposing the carotid artery through a neck incision, cutting the vessel wall, and completely removing the atherosclerotic plaques and diseased intima that are causing the narrowing. The vessel and incision are then sutured to restore normal vessel diameter and blood flow, improving blood supply to the brain. Carotid artery stenting is a minimally invasive interventional procedure for treating atherosclerotic carotid artery stenosis. It involves dilating the narrowed vessel through endovascular manipulation and implanting a stent to restore blood supply to the brain and prevent ischemic stroke. Both procedures require revascularization.

[0003] Existing revascularization devices, such as balloon occlusion catheters, have an upper limit on their outer diameter, which is constrained by the inner diameter of vessels like the femoral artery and common carotid artery. This prevents them from achieving the same size as the blood flow reversal pathway in revascularization systems accessed via the carotid artery. The pressure difference between the common carotid artery and femoral vein is relatively small, making it difficult to form a reverse flow. Secondly, during the delivery of therapeutic devices such as balloons and stents through the lumen of the balloon occlusion catheter, they occupy the lumen, further resulting in insufficient pressure difference. Consequently, effective reverse flow cannot be formed during the critical processes of balloon dilation and stent implantation, leading to plaque detachment at the stenotic lesion site and drifting with the blood to intracranial vessels, causing distal embolism. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a dual-path backflow protection device via the femoral artery.

[0005] To achieve the above objectives, the present invention employs the following technical solution: a dual-path reflux protection device via the femoral artery, comprising: balloon catheter; The balloon catheter is inserted into the first target area via the femoral artery; The balloon catheter is connected to a first circuit and a second circuit via a Y-type connector on one side, and a counterflow pump is connected between the first circuit and the second circuit. The other ends of the first circuit and the second circuit are connected to a venous sheath, which extends into the second target area; The operation of the counter-current pump switches the protection device from the first state to the second state. In the first state, blood from the first target area enters the first chamber of the counterflow pump from the balloon catheter and the first circuit, and blood from the second chamber of the counterflow pump enters the second target area through the second circuit and the venous sheath; In the second state, blood from the first target area enters the second chamber of the counterflow pump from the balloon catheter and the second circuit, while blood from the first chamber of the counterflow pump enters the second target area through the first circuit and the venous sheath.

[0006] As a further description of the above technical solution: the first circuit includes a first one-way valve, the input end of the first one-way valve is connected to the Y-type connector, the output end of the first one-way valve is connected to the input end of the first blood filter, the output end of the first blood filter is connected to the first chamber of the counterflow pump, the other side of the first chamber is connected to the input end of the second one-way valve, and the output end of the second one-way valve is connected to the vein sheath through a pipeline.

[0007] As a further description of the above technical solution: the second circuit includes a third one-way valve, the input end of the third one-way valve is connected to the Y-type connector, the output end of the third one-way valve is connected to the input end of the second blood filter, the output end of the second blood filter is connected to the second chamber of the counterflow pump, the other side of the second chamber is connected to the input end of a fourth one-way valve, and the output end of the fourth one-way valve is connected to the venous sheath through a pipeline.

[0008] As a further description of the above technical solution: the balloon catheter includes an outer tube and an inner tube, and a third cavity is formed between the outer tube and the inner tube. A balloon communicating with the third cavity is provided on the outside of the outer tube. An inflation cavity is provided on the side of the outer tube away from the balloon. An aspiration cavity and an instrument cavity are provided on the side of the inner tube away from the balloon. The aspiration cavity is communicating with the Y-type connector.

[0009] As a further description of the above technical solution: the countercurrent pump includes a pump body, a first piston is provided inside the pump body, a handle extending to the outside of the pump body is provided on one side of the first piston, one end face of the pump body cooperates with the handle through a sealing section, the first piston divides the inner side of the pump body into a first cavity and a second cavity, and an inlet and an outlet are respectively provided at the first cavity and the second cavity.

[0010] As a further description of the above technical solution: the first blood filter and the second blood filter have the same structure. The first blood filter includes a housing, and a delivery pipe is provided on the inner side of the housing. A check valve and a filter screen are provided at the input end of the delivery pipe, and a flow control knob is provided on one side of the delivery pipe.

[0011] As a further description of the above technical solution: the first check valve, the second check valve, the third check valve and the fourth check valve have the same structure, including a valve body, a telescopic component is provided inside the valve body, and a sealing disc is provided on one side of the telescopic component. In the natural state, the sealing disc abuts against the input end of the valve body.

[0012] As a further description of the above technical solution: a first interface is provided on one side of the vein sheath, and a second interface extending outward is provided on one side of the vein sheath. The second interface is connected to the first circuit and the second circuit. An dilator is provided on the inner side of the vein sheath through the first interface.

[0013] As a further description of the above technical solution: In the first state, the first piston of the counterflow pump moves toward the second chamber, the first one-way valve opens, the second one-way valve closes, the third one-way valve closes, and the fourth one-way valve opens, so that blood in the first target area enters the first chamber and blood in the second chamber enters the second target area.

[0014] As a further description of the above technical solution: In the second state, the first piston moves toward the first cavity, the first one-way valve closes, the second one-way valve opens, the third one-way valve opens, the fourth one-way valve closes, the blood in the first cavity enters the second target area, and the blood in the first target area enters the second cavity.

[0015] The above technical solution has the following advantages or beneficial effects: This application involves inserting a balloon catheter via the femoral artery into the first target area of ​​the common carotid artery to occlude it. Blood is then transported to the second target area of ​​the femoral vein via a counterflow pump and first and second circuits, thus redirecting blood flow from the common carotid artery back to the venous sheath of the femoral vein. This ensures a sufficient pressure differential and effective counterflow between the carotid artery and femoral vein throughout the carotid artery stenosis treatment procedure. This prevents plaque from detaching from the stenotic lesion and drifting into intracranial vessels during interventional treatments such as balloon angioplasty and stent implantation, thereby improving safety. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the protective device proposed in this invention. Figure 2 This is a diagram showing the usage status of the protection device proposed in this invention; Figure 3 This is a schematic diagram illustrating the structural principle of the balloon catheter in this invention; Figure 4 This is a schematic diagram of the countercurrent pump in this invention. Figure 5 This is a schematic diagram illustrating the structural principle of the blood filter in this invention; Figure 6 This is a schematic diagram illustrating the structural principle of the blood filter in its low-flux state according to the present invention. Figure 7 This is a schematic diagram illustrating the structural principle of the blood filter in the blocked state in this invention; Figure 8 This is a schematic diagram of the one-way valve in this invention. Figure 9 This is a schematic diagram of the structural principle of the one-way valve when it is open in this invention; Figure 10 This is a schematic diagram illustrating the structural principle of the venous sheath and dilator in this invention.

[0018] Legend: 1. Balloon catheter; 101. Outer tube; 102. Inner tube; 103. Balloon; 104. Inflation chamber; 105. Aspiration chamber; 106. Instrument chamber; 2. Y-connector; 3. Counterflow pump; 301. Pump body; 302. First piston; 303. Handle; 304. Sealing section; 305. Inlet; 306. Outlet; 4. Vein sheath; 401. First interface; 402. Second interface; 403. Diverter; 5. First check valve; 501. Valve body; 502. Telescopic assembly; 503. Occlusion disc; 6. First blood filter; 601. Housing; 602. Delivery tube; 603. Check valve; 604. Filter screen; 605. Flow control knob; 7. Second check valve; 8. Third check valve; 9. Second blood filter; 10. Fourth check valve. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Reference Figures 1-10 An embodiment of the present invention provides a dual-path reflux protection device via the femoral artery, comprising: a balloon catheter 1; the balloon catheter 1 extends into a first target area via the femoral artery; one side of the balloon catheter 1 is connected to a first circuit and a second circuit via a Y-connector 2, and a reflux pump 3 is connected between the first circuit and the second circuit; the other end of the first circuit and the second circuit is connected to a venous sheath 4, which extends into the second target area; by activating the reflux pump 3, the protection device is switched from a first state to a second state; in the first state, blood in the first target area enters the first chamber of the reflux pump 3 from the balloon catheter 1 and the first circuit, and blood in the second chamber of the reflux pump 3 enters the second target area via the second circuit and the venous sheath 4; in the second state, blood in the first target area enters the second chamber of the reflux pump 3 from the balloon catheter 1 and the second circuit, and blood in the first chamber of the reflux pump 3 enters the second target area via the first circuit and the venous sheath 4.

[0021] In this embodiment, the balloon catheter 1 is inserted through the femoral artery into the first target area of ​​the common carotid artery. The common carotid artery is blocked by the balloon 103, and blood is delivered to the second target area of ​​the femoral vein on the other side through the counterflow pump 3 and the first and second circuits. The blood from the common carotid artery is returned to the venous sheath of the femoral vein. The counterflow pump 3 alternately connects the first and second circuits to deliver blood, ensuring that there is always a sufficient pressure difference and effective counterflow between the carotid artery and the femoral vein during the carotid artery stenosis treatment surgery. This can prevent plaque from dislodging from the stenosis lesion and drifting into intracranial blood vessels during interventional treatments of carotid artery stenosis, such as balloon dilation and stent implantation, thus improving safety.

[0022] Reference Figures 1-2 The first circuit includes a first one-way valve 5, the input end of which is connected to a Y-type connector 2, the output end of which is connected to the input end of a first blood filter 6, the output end of which is connected to the first chamber of a counterflow pump 3, the other side of which is connected to the input end of a second one-way valve 7, and the output end of the second one-way valve 7 is connected to a vein sheath 4 through a pipeline.

[0023] In this embodiment, the first circuit and the second circuit are connected in parallel to the balloon catheter 1 through the Y-type connector 2 to form a flow channel. The first circuit controls the blood to flow unidirectionally into the first blood filter 6 through the first one-way valve 5. After filtering the plaque debris in the blood, it is delivered to the first chamber of the counterflow pump 3. When the counterflow pump 3 compresses the first chamber, the blood flows unidirectionally out from the second one-way valve 7 to the venous sheath 4.

[0024] The second circuit includes a third check valve 8, the input end of which is connected to a Y-connector 2, the output end of which is connected to the input end of a second blood filter 9, the output end of which is connected to the second chamber of a counterflow pump 3, the other side of which is connected to the input end of a fourth check valve 10, and the output end of the fourth check valve 10 is connected to a vein sheath 4 via a pipeline.

[0025] In this embodiment, the second circuit controls the unidirectional flow of blood into the second blood filter 9 through the third one-way valve 8. After filtering the plaque debris in the blood, it is delivered to the second chamber of the counterflow pump 3. When the counterflow pump 3 compresses the second chamber, the blood flows out unidirectionally from the fourth one-way valve 10 to the venous sheath 4. The first circuit and the second circuit are delivered alternately by the counterflow pump 3 to ensure that there is always a sufficient pressure difference and effective counterflow between the carotid artery and the femoral vein during the carotid artery stenosis treatment surgery.

[0026] Reference Figure 3 The balloon catheter 1 includes an outer tube 101 and an inner tube 102. A third cavity is formed between the outer tube 101 and the inner tube 102. A balloon 103 communicating with the third cavity is provided on the outside of the outer tube 101. An inflation cavity 104 is provided on the side of the outer tube 101 away from the balloon 103. An aspiration cavity 105 and an instrument cavity 106 are provided on the side of the inner tube 102 away from the balloon 103. The aspiration cavity 105 is connected to the Y-type connector 2.

[0027] In this embodiment, balloon 103 is a compliant balloon, and the material can be TPU, silicone, or other materials. A certain gap exists between the outer tube 101 and the inner tube 102, forming a third cavity, which is connected to balloon 103. The materials of the outer tube 101 and the inner tube 102 can be nylon, Pebax, PTFE, or other suitable single-layer materials, or multi-layer composite materials, such as Pebax, 304 stainless steel braided tubing, PTFE three-layer composite, or composites of two, three, or more materials. The inflation cavity 104 is connected to the third cavity, and balloon 103 can be inflated by injecting contrast agent, saline, or a mixture of both, as well as other liquids or gases into the inflation cavity 104. The instrument cavity 106 is connected to the inner lumen of the inner tube 102, and can be used to deliver guidewires or other diagnostic or therapeutic instruments. One end of the aspiration cavity 105 is connected to the inner lumen of the inner tube 102, and the other end is connected to the Y-connector 2 for blood delivery.

[0028] Reference Figure 4 The countercurrent pump 3 includes a pump body 301. A first piston 302 is provided on the inner side of the pump body 301. A handle 303 extending to the outer side of the pump body 301 is provided on one side of the first piston 302. One end face of the pump body 301 cooperates with the handle 303 through a sealing section 304. The first piston 302 divides the inner side of the pump body 301 into a first cavity and a second cavity. An inlet 305 and an outlet 306 are respectively provided in the first cavity and the second cavity.

[0029] In this embodiment, a first piston 302 is provided inside the countercurrent pump 3. The first piston 302 can be made of silicone or other materials and is tightly fitted to the pump body 301. The first piston 302 is connected to a handle 303, and pushing or pulling the handle 303 can move the first piston 302 within the pump body 301. The first piston 302 divides the inner side of the pump body 301 into a first chamber and a second chamber. The first chamber and the second chamber are respectively provided with an inlet 305 and an outlet 306 for transporting blood. A sealing section 304 connects the handle 303 and the pump body 301, achieving a seal between the handle 303 and the pump body 301, and allowing the handle 303 to move within a certain range. By pushing or pulling the handle 303 to move the first piston, the two working states are switched, driving blood to flow alternately through the first circuit and the second circuit.

[0030] Reference Figure 5 The first blood filter 6 and the second blood filter 9 have the same structure. The first blood filter 6 includes a housing 601. A delivery pipe 602 is provided inside the housing 601. A check valve 603 and a filter screen 604 are provided at the input end of the delivery pipe 602. A flow control knob 605 is provided on one side of the delivery pipe 602.

[0031] In this embodiment, the input end of the first blood filter 6 is connected sequentially to the first one-way valve 5, the Y-connector 2, and the suction chamber 105 of the balloon catheter 1 via a connecting pipe. A delivery pipe 602 is provided inside the housing 601, and a check valve 603 is provided at the input end of the delivery pipe 602 to ensure that blood can only flow from the input end to the output end of the delivery pipe 602, preventing backflow. The filter screen 604 can be made of a woven mesh of polymer or other biocompatible materials, with a mesh size of 5μm-400μm. A flow control knob 605 is provided on one side of the delivery pipe 602. Two intersecting flow channels are formed inside the delivery pipe 602, and the cross-sectional areas of the two channels are different. By adjusting the flow control knob 6052, the two flow channels or the curved surface of the flow control knob 605 can be aligned with the axial direction of the delivery pipe 602, thus achieving blood flow blocking (see reference). Figure 7 ), low throughput (refer to) Figure 6 ), high throughput (refer to) Figure 5Switching between three flow control methods.

[0032] Reference Figures 8-9 The first check valve 5, the second check valve 7, the third check valve 8 and the fourth check valve 10 have the same structure, including a valve body 501. A telescopic component 502 is provided inside the valve body 501. A sealing disc 503 is provided on one side of the telescopic component 502. In the natural state, the sealing disc 503 abuts against the input end of the valve body 501.

[0033] In this embodiment, the telescopic component 502 includes a gas chamber disposed on the inner wall of the valve body 501. A second piston is disposed inside the gas chamber, and the second piston is tightly fitted with the gas chamber. A certain volume of inert gas is filled between the second piston and the gas chamber. The second piston is connected to the sealing disc 503 via a connecting rod. Under normal conditions, the pressure of the inert gas pushes the second piston to drive the connecting rod and the sealing disc 503 to close the input end of the one-way valve. When the one-way valve is connected to the backflow protection device, when the pressure at the output end is greater than the pressure at the input end, the sealing disc 503 continues to maintain the sealing effect on the input end of the one-way valve. When the pressure at the output end is less than the pressure at the input end and a certain pressure difference is reached, the sealing disc 503 will drive the second piston to compress the inert gas via the connecting rod. The sealing disc 503 will move away from the valve body 501 and lose its sealing effect on the one-way valve, realizing one-way flow. Compared with the existing one-way valve core structure, the blood pressure loss at the input and output ends is smaller.

[0034] Reference Figure 10 A first interface 401 is provided on one side of the vein sheath 4, and a second interface 402 extending outward is provided on one side of the vein sheath 4. The second interface 402 is connected to the first circuit and the second circuit. An dilator 403 is provided on the inner side of the vein sheath 4 through the first interface 401.

[0035] In this embodiment, the vein sheath 4 and the dilator 403 can be made of polymer materials. A silicone hemostatic valve is provided in the first interface 401 of the vein sheath 4 to cooperate with the dilator 403.

[0036] In the first state, the first piston 302 of the counterflow pump 3 moves toward the second chamber, the first one-way valve 5 opens, the second one-way valve 7 closes, the third one-way valve 8 closes, and the fourth one-way valve 10 opens, so that blood from the first target area enters the first chamber and blood from the second chamber enters the second target area.

[0037] In this embodiment, the piston 302 is pushed toward the second chamber, the volume of the first chamber increases to form a negative pressure, the first one-way valve 5 opens and the third one-way valve 8 closes, blood flows into the first chamber from the first circuit, the second one-way valve 7 closes and the fourth one-way valve 10 opens, blood in the second chamber enters the second target area from the second circuit.

[0038] In the second state, the first piston 302 moves toward the first chamber, the first one-way valve 5 closes, the second one-way valve 7 opens, the third one-way valve 8 opens, and the fourth one-way valve 10 closes. Blood in the first chamber enters the second target area, and blood in the first target area enters the second chamber.

[0039] In this embodiment, the first piston 302 moves towards the first chamber, increasing the volume of the second chamber and creating negative pressure. The first one-way valve 5 closes, and the third one-way valve 8 opens, allowing blood to flow into the second chamber from the second circuit. The second one-way valve 7 opens, and the fourth one-way valve 10 closes, allowing blood in the first chamber to enter the second target area from the first circuit. This ensures a sufficient pressure difference between the common carotid artery and the femoral vein, enabling blood to continuously flow into the femoral vein through the backflow protection device, thereby improving the safety of balloon angioplasty or stent implantation procedures of the common carotid artery.

[0040] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0041] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dual-path backflow protection device via the femoral artery, characterized in that, include: Balloon catheter (1); The balloon catheter (1) is inserted into the first target area via the femoral artery; The balloon catheter (1) is connected to a first circuit and a second circuit via a Y-type connector (2) on one side, and a counterflow pump (3) is connected between the first circuit and the second circuit. The other ends of the first circuit and the second circuit are connected to a venous sheath (4), which extends into the second target area; The protection device is switched from the first state to the second state by the operation of the counterflow pump (3); In the first state, blood from the first target area enters the first chamber of the counterflow pump (3) from the balloon catheter (1) and the first circuit, and blood in the second chamber of the counterflow pump (3) enters the second target area through the second circuit and the venous sheath (4); In the second state, blood from the first target area enters the second chamber of the counterflow pump (3) from the balloon catheter (1) and the second circuit, and blood in the first chamber of the counterflow pump (3) enters the second target area through the first circuit and the venous sheath (4).

2. The protection device according to claim 1, characterized in that: The first circuit includes a first one-way valve (5), the input end of the first one-way valve (5) is connected to the Y-type connector (2), the output end of the first one-way valve (5) is connected to the input end of the first blood filter (6), the output end of the first blood filter (6) is connected to the first chamber of the counterflow pump (3), the other side of the first chamber is connected to the input end of the second one-way valve (7), and the output end of the second one-way valve (7) is connected to the vein sheath (4) through a pipeline.

3. The protection device according to claim 2, characterized in that: The second circuit includes a third check valve (8), the input end of which is connected to the Y-connector (2), the output end of which is connected to the input end of the second blood filter (9), the output end of which is connected to the second chamber of the counterflow pump (3), the other side of which is connected to the input end of the fourth check valve (10), and the output end of the fourth check valve (10) is connected to the vein sheath (4) through a pipeline.

4. The protection device according to claim 1, characterized in that: The balloon catheter (1) includes an outer tube (101) and an inner tube (102). A third cavity is formed between the outer tube (101) and the inner tube (102). A balloon (103) communicating with the third cavity is provided on the outside of the outer tube (101). An inflation cavity (104) is provided on the side of the outer tube (101) away from the balloon (103). An aspiration cavity (105) and an instrument cavity (106) are provided on the side of the inner tube (102) away from the balloon (103). The aspiration cavity (105) is communicating with the Y-type connector (2).

5. The protection device according to claim 3, characterized in that: The countercurrent pump (3) includes a pump body (301), a first piston (302) is provided on the inner side of the pump body (301), a handle (303) is provided on one side of the first piston (302) extending to the outer side of the pump body (301), one end face of the pump body (301) cooperates with the handle (303) through a sealing section (304), the first piston (302) divides the inner side of the pump body (301) into a first cavity and a second cavity, and an inlet (305) and an outlet (306) are respectively provided at the first cavity and the second cavity.

6. The protection device according to claim 3, characterized in that: The first blood filter (6) and the second blood filter (9) have the same structure. The first blood filter (6) includes a housing (601), and a delivery pipe (602) is provided on the inner side of the housing (601). A check valve (603) and a filter screen (604) are provided at the input end of the delivery pipe (602). A flow control knob (605) is provided on one side of the delivery pipe (602).

7. The protection device according to claim 3, characterized in that: The first check valve (5), the second check valve (7), the third check valve (8) and the fourth check valve (10) have the same structure, including a valve body (501). A telescopic component (502) is provided inside the valve body (501), and a sealing disc (503) is provided on one side of the telescopic component (502). In the natural state, the sealing disc (503) abuts against the input end of the valve body (501).

8. The protection device according to claim 1, characterized in that: A first interface (401) is provided on one side of the vein sheath (4), and a second interface (402) extending outward is provided on one side of the vein sheath (4). The second interface (402) is connected to the first circuit and the second circuit. An dilator (403) is provided on the inner side of the vein sheath (4) through the first interface (401).

9. The protection device according to claim 5, characterized in that: In the first state, the first piston (302) of the counterflow pump (3) moves toward the second cavity, the first one-way valve (5) opens, the second one-way valve (7) closes, the third one-way valve (8) closes, and the fourth one-way valve (10) opens, so that blood in the first target area enters the first cavity and blood in the second cavity enters the second target area.

10. The protection device according to claim 5, characterized in that: In the second state, the first piston (302) moves toward the first cavity, the first one-way valve (5) closes, the second one-way valve (7) opens, the third one-way valve (8) opens, the fourth one-way valve (10) closes, the blood in the first cavity enters the second target area, and the blood in the first target area enters the second cavity.

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