JP4395435B2 - Blood flow control graft - Google Patents

Description

  The invention of this application relates to the structure of a blood flow control graft.

  Recently, by using a special synthetic resin, various grafts (artificial blood vessels) having antithrombogenicity and excellent biocompatibility have been provided. For example, blood as a dialysis shunt It is used effectively for purification therapy.

  In the case of a dialysis shunt, the graft is generally connected (implanted) between the artery and vein in the patient's arm (upper arm and forearm), and is short-circuited from the artery side to the vein side without going through the microcirculatory system. A large amount of blood is shed.

  Therefore, if a dialyzer such as a dialyzer is connected to the graft portion through a puncturing means, unnecessary metabolites in blood can be efficiently removed (see Patent Document 1).

  However, all of the conventional grafts have the same diameter in the entire conduit, and there is a problem that stenosis occurs near the outflow tract where the graft is connected to the vein, that is, near the venous anastomosis. This stenosis is a narrowing that is not a natural part of blood vessels, and there is a problem that the vein progresses until it is completely occluded unless it is opened by surgery (angioplasty).

  Such stenosis is considered to be basically caused by the formation of new intima, that is, the vascular reaction to an abnormal state. For example, the following may be assumed as a mechanism that may specifically contribute to the growth of stenosis.

That is, the venous blood flow is specifically about 10 to 20 times higher than the normal blood flow. This results in turbulent flow that is smooth or not laminar, resulting in constriction. Another factor to vein through the graft Ru is connected directly to the arterial, venous is to be exposed to higher blood pressure than normal. The arterial blood pressure is specifically about 100 mmHg, while the venous blood pressure is specifically about 5 mmHg. As a result, the vein becomes arterial in response to, for example, thickening the vein wall, which can contribute to stenosis.

  A further possible factor is that the venous blood flow is pulsatile in the presence of the graft. There is a difference in compliance between the semi-hardened graft and the compliant vein. As a result, the pulsatile flow results in a concentration of oscillating stress at the joint, i.e., the suture line between the graft and the vein. Although sutures usually do not break, stenosis can occur in response to oscillatory stresses concentrated at the joint.

  At present, the stenosis has a low clinical primary patency rate of about 50 to 60% (6 to 12 months after surgery), which is a serious clinical problem.

Japanese Patent Laying-Open No. 2003-245343 (Specifications page 1-4, FIG. 1-8)

  The invention of this application was made in order to solve the above-described problems. A narrow-diameter portion having a small cross-sectional area is provided in a part of the conduit, and the narrow-diameter portion leads to the vein side. Appropriately controls the state of the blood flow to be supplied, suppresses turbulence on the downstream side of the graft, reduces the influence of blood pressure values and pulsations acting on the vein side, and prevents the occurrence of stenosis as described above. An object of the present invention is to provide a blood flow control graft that can be suppressed as much as possible.

  In order to achieve the above object, the invention of this application includes the following problem solving means.

(1) First Problem Solving Means According to a first problem solving means of the present invention, an extracorporeal circuit is formed by being connected between blood vessels of a human body, and a small diameter portion is provided in a part of a conduit. A blood flow control graft that is formed as a single continuous tube including the diameter portion, and is made of a continuous porous synthetic resin material. The narrow diameter portion is similar to the cross-sectional shape of the graft conduit. The cross-sectional shape is provided so as to be coaxial with the graft conduit, and the inlet side and the outlet side portions thereof are each formed in a funnel shape .

  According to the graft having such a configuration, first, the blood flow is reduced in the narrow diameter portion to suppress the flow rate, and then diffused by the enlargement of the pipe cross-sectional area, resulting in a rectified and gentle flow.

As a result, it is possible to reduce the turbulence of the blood flow flowing in the graft duct , and even when the graft is connected between the artery and the vein, the blood pressure on the vein side is kept low, and the vein wall Effects of pulsation based on differences in compliance between a semi-hardened graft and a compliant vein, avoiding thickening and arterialization , i.e. vibration stress due to pulsatile flow between the graft and vein The problem of concentrating on the suture line portion can be substantially solved . Its these results, it can be as much as possible effectively prevent the occurrence of a conventional such constriction.

  Such a small-diameter portion can be realized, for example, by deforming the graft into a flat state by sandwiching the graft from the outside with some clamping means, and reducing and changing the pipe cross-sectional area by the clamping.

However, such compressive deformation cannot form a uniform and stable narrow pipe-shaped portion, and even if the passage cross-sectional area can be simply reduced, the flow to the venous side can be appropriately layered. It is not possible to effectively suppress the generation of turbulent flow. Rather, the turbulence is increased by the line shape changes, or even potential to is rather grow stenosis.

  In addition, fatigue and damage of the graft itself become a problem due to repeated compressive deformation. Therefore, a high elastic modulus of the graft material is also required, and the material is limited.

Furthermore, since an external device such as a clamping means is required, the cost is significantly increased accordingly.

However, if the present invention, since the fixedly small diameter portion in a part of the conduit of the graft itself is adapted to be provided, the structure is simple, pipe shape with a constant, or more narrow There is no problem like wearing type.

In the configuration of the present invention, the upper Kigu rafts whole including the small-diameter portion is characterized in that it is formed integrally with the successive pipes of one.

Therefore , compared to the type in which a separate small diameter tube is partially joined and integrated, the inner peripheral surface of the conduit in the graft becomes a continuous smooth surface without a stepped portion, and blood is more It will flow smoothly. Therefore, adhesion of thrombus and the like does not occur.

  In addition, the seamless structure has a high overall strength and excellent safety.

In particular, in the case of the present invention, the graft itself is made of a continuous porous synthetic resin material, which is very smooth in terms of material and has a smooth smooth surface and is less prone to thrombus closure. Is.

Furthermore, since the moldability is good, it is suitable for integral molding of the seamless structure.

In the configuration of the present invention, the upper KiHoso diameter portion forms a cross-sectional shape and similar cross-sectional shape of the graft conduit, that provided in the graft conduit coaxially.

  According to such a configuration, the blood flow that flows from the upstream side of the small-diameter portion to the downstream side of the small-diameter portion becomes a concentric continuous flow throughout, and more effectively suppresses the turbulence. The rectifying effect is increased.

Therefore, the superiority is much higher than when the graft is compressed and deformed by using the external clamping means described above.

In addition, the configuration of the present invention is characterized in that, in the above-described configuration, the inlet side and the outlet side portions of the narrow-diameter portion each have a funnel shape.

  Therefore, according to the same configuration, first, the flow can be smoothly reduced on the inlet side of the small diameter portion, and a more stable reduced flow can be obtained. On the other hand, Karman vortices at the downstream outlet portion are less likely to occur. Thus, the above-described turbulent flow suppression and rectification effects are improved.

(2) Second Problem Solving Means According to a second problem solving means of the present invention, in the configuration of the first problem solving means, the narrow-diameter portion has a predetermined length in the tube length direction. It is characterized by being.

According to such a configuration, it is possible to flow in a desired contracted state within a desired time, a more stable contracted flow can be obtained, and turbulent flow suppression and rectification effects are further improved.

(3) Third Problem Solving Means According to a third problem solving means of the present invention, in the configuration of the first or second problem solving means, the outer peripheral portion of the small diameter portion is made of a continuous porous synthetic resin material. It is characterized in that a reinforcing cover having a sleeve structure is fitted .

According to such a configuration, the graft having the small-diameter portion is configured as a continuous tube having an equal diameter as a whole by fitting the reinforcing cover of the sleeve structure made of the same continuous porous synthetic resin material, The rigidity of the narrow-diameter part is improved. For example, even when configured and used as a dialysis shunt, etc., a proper bending shape (loop shape) is realized as a whole without causing excessive bending partially, and blood Will flow smoothly.

  As a result, according to the present invention, an effective graft capable of effectively suppressing the occurrence of stenosis as in the prior art can be provided at low cost.

  Therefore, it is also effective as a shunt for blood purification therapy such as a dialysis shunt and other various shunts.

(Best Embodiment 1)
1 and 2 show the configuration of the blood flow control graft according to the invention of this application, and FIG. 3 further shows the configuration and use state of the shunt for animal experiments using the blood flow control graft. 4 shows the configuration and use state of a human dialysis shunt configured using the blood flow control graft.

(Basic configuration)
In FIG. 1, reference numeral 1 denotes a blood flow control graft (hereinafter simply referred to as a graft) in this embodiment. The graft 1 is integrally formed into a seamless structure with a continuous porous synthetic resin material such as E-PTFE, for example, and a funnel-shaped thin portion is formed in the middle (part) of the pipe body portion (the pipe line 1a) having a predetermined length. A diameter portion 2 is provided.

  For example, the small-diameter portion 2 has an inner diameter e (e = 2 mm) and an axial length in the middle of the tubular graft 1 having a wall thickness t (t = 0.7 mm) and an inner diameter a (a = 5 mm). C (c = 4 mm), a small-diameter tube portion having an axial length d (d = 4 mm) of each of the inlet and outlet funnels 2b, 2b of the blood flow is formed on the outer periphery thereof. Similarly, a reinforcing cover 3 having a sleeve structure made of a continuous porous synthetic resin material such as E-PTFE is fitted and fixed. The graft 1 having the small-diameter portion 2 is configured as a continuous pipe having an equal diameter as a whole by the fitting of the reinforcing cover 3, and the rigidity of the small-diameter portion 2 is improved. Even when configured and used as a dialysis shunt, etc., an appropriate bending shape (loop shape) is realized as a whole without causing excessive bending partially, and blood flows smoothly. ing.

  Note that the dimension b in FIG. 1 is the length c of the constant diameter portion 2a portion at the center of the small diameter portion 2 and the axial length of the funnel portions 2b and 2b portions on both the inlet and outlet sides before and after the constant diameter portion 2a. The axial length of the entire small diameter portion 2 including the lengths d and d is shown.

(Basic action)
Next, the blood flow control action of the graft 1 configured as described above will be described with reference to FIG.

Now, for example, the blood flow B ₁ from the artery side flows into the narrow diameter portion 2 of the graft 1 as shown in FIG. 2, and flows out to the vein side as the blood flow B ₂ through the small diameter portion 2. Let's go.

In this case, the blood flow B ₁ from the arterial side is first reduced in diameter while the cross-sectional area is gradually reduced by the inlet-side funnel portion 2b in which the inner diameter a gradually decreases from the narrow diameter portion 2 while the flow rate is suppressed. becomes e / a = 2/5) has been constant diameter portion 2a partial fast accelerated flow speed in contraction, turbulence components in the blood stream B ₁ is a laminar flow into a negated by the tube axis direction, stable It becomes the flow.

  On the other hand, this reduced flow has a cross-sectional area enlarged at the outlet-side funnel portion 2b of the small-diameter portion 2 in which the tube diameter (channel diameter) gradually increases (from e = 2 mm to a = 5 mm), and the flow velocity greatly decreases. A stable laminar flow that flows uniformly and smoothly through the entire graft line having an inner diameter a (a = 5 mm) is obtained.

Further, the pressure fluctuation due to the pulsation on the blood flow B ₁ side is effectively absorbed by the passage diameter being greatly enlarged on the outlet side through the small diameter portion 2 (from e = 2 mm to a = 5 mm). Thus, the blood flow B ₂ to the venous side has little pressure fluctuation. The effect of blood pressure is also reduced by the same action.

(Animal experimentation)
A: Experimental method A hybrid dog (body weight: 10 to 15 kg) was used as a target animal, and a looped shunt was created between the artery A and vein V of the thigh 5 under intravenous anesthesia. Two types of shunts were created. One is a device (FCG) having a small-diameter portion 2 for blood flow control according to the present embodiment shown in FIG. 3, for example, and the other is a conventional device having no thin-diameter portion 2 shown in FIG. 6, for example. (CG).

  3 and 6, reference numeral 1 is a graft, 1 a is a conduit in the graft 1, 2 is a narrow diameter portion (only in the case of FIG. 3), 5 is a thigh, and 11 is an anastomosis on the artery side of the graft 1. , 12 is the venous anastomosis part of graft 1, A is an artery, and V is a vein.

  Then, as a method for evaluating each blood flow rate, blood flow velocity, and anastomosis stenosis rate, for example, using MRI, the blood flow rate and blood flow velocity for each are fixed-point measured (in a linear part on the loop graft vein side). At the same time, the stenosis was measured by DSA (angiography apparatus).

  The evaluation time is measured every two weeks immediately after the operation, and is measured when each of the graft (FCG) having the blood flow control function and the conventional non-blood flow control graft (CG) of the present embodiment is occluded. Finished.

  The expectation of the effect expression by this animal experiment is based on the following two clinical experiences as a doctor of the present inventor so far.

  (1) First, clinically, in the case of a native shunt (autologous intra-arteriovenous shunt), stenosis is unlikely to occur on the shunt vein side in a case where the arteriovenous anastomosis is constricted. From clinical data, if the diameter of the arteriovenous anastomosis is at least 1.5 mm, blood flow that does not interfere with dialysis is secured.

  (2) Next, clinically, in cases where stenosis was caused by twisting of the graft, the onset of stenosis at the venous graft anastomosis was relatively slow.

  These results suggested that the suppression of blood flow may be a major factor in suppressing venous anastomosis stenosis of the graft.

B: Measurement results The graft (FCG) in FIG. 3 having the blood flow control function by the small diameter portion 2 and the non-blood flow control graft (CG) in FIG. A comparative study was conducted on three items: changes in flow rate over time and changes in vein diameter at the narrowest stenosis.

as a result,
1) Regarding the shunt blood flow, the graft (FCG) in FIG. 3 having the blood flow control function by the small diameter portion 2 showed a substantially constant decrease in blood flow.

  2) The flow rate of shunt blood is the same as that of the graft (FCG) in FIG. 3 having the blood flow control function by the small diameter portion 2, and the non-blood flow control graft (CG) in FIG. 6 without the small diameter portion. Increased until about 4 to 12 weeks and then showed a decreasing trend.

  3) With regard to the vein diameter of the narrowest stenosis, each of the graft (FCG) in FIG. 3 having the blood flow control function by the narrow diameter part 2 and the non-blood flow control graft (CG) in FIG. As a result, the diameter of the most narrowed portion of the non-blood flow control graft (CG) was significantly thick from 1 to 2 weeks after the operation, and the blood flow control graft (FCG) and the non-blood flow were 4 to 5 weeks after the operation. There was no significant difference in the control graft (CG) (p <0.05, where p is a statistical value).

  On the other hand, after the 8th week after the operation, the stenosis diameter of the blood flow control graft (FCG) tended to become significantly thicker, and the significant difference tended to increase over time. In the t-test test using statistical methods, the blood flow control graft (FCG) narrows at 0.08272 mm / day and the non-blood flow control graft (CG) narrows at 0.1024 mm / day. Showed a trend.

C: Discussion As a result of this animal experiment, if the blood flow volume in the shunt portion is suppressed and turbulence is prevented, vein stenosis (see reference numeral 6 in FIG. 6) occurring in the vein side anastomosis portion 12 of the graft can be effectively reduced. found.

  As described above, the stenosis 6 of the graft vein side anastomosis part of the non-blood flow control graft (CG) is caused by the shunt blood flow immediately after the operation, but once the vein diameter is enlarged, 8 weeks (2 months) Later it begins to narrow. Thrombus occlusion, which is the biggest problem in clinical practice, often occurs between 6 and 7 months after surgery, but as you can see from this experiment, stenosis has begun early after surgery. The blood flow control graft (FCG) of FIG. 3 provided with the small diameter portion 2 had an effect of suppressing the change.

  The effect of suppressing stenosis by the blood flow control graft (FCG) can be explained as follows. That is, in terms of hemodynamics, shear stress is proportional to blood flow in a closed circuit. However, since the blood flow control graft (FCG) having the small diameter portion 2 suppresses the blood flow volume, it has a low shear stress at the anastomosis portion, and is generally accepted in the arterial system. This contradicts the explanation that low shear stress is a cause of stenosis.

  On the other hand, it has already been proved that the narrowing of the arterial system occurring in the vortex site caused by turbulence is caused by the low shear stress caused by the vortex (for example, J Vasc Surg. 1987; 5: 413- 420., Strok.1997; 28: 993-998., Arterioscler Thromb Vasc Biol.1998; 18: 708-716., Eur J Vasc Endovasc Surg.1997; 13: 263-271., J Magn Reson Imaging.1995; 5: 640-647., Circulation.1996; 94: 3257-3262., J Vasc Surg.1994; 19: 58-63., J Vasc Surg.1994; 19: 426-434., Arterioscler Thromb.1992; 12 : 1245-1253 ... etc.). The turbulent flow component is rectified by contraction in the small diameter portion 2 and is reliably reduced by the flow velocity being slowed downstream of the small diameter portion 2. As a result, the blood flow control graft (FCG) further reduces the low shear stress.

  In addition, as described above, there is a study that pressure fluctuation caused by arterial pulsation is a factor of stenosis. Also in this case, the blood flow control graft (FCG) shown in FIG. 3 can effectively cope with the small diameter portion 2 and the pressure fluctuation absorbing action by expanding the pipe diameter on the downstream side.

  Of course, various other chemical mediators are acting on the intimal cells of the blood vessels to cause intimal hyperplasia. Therefore, it is difficult to elucidate all of these various factors at this stage.

  However, the results of the above animal experiments clearly show that the amount of blood flowing from the artery side to the vein side is suppressed, the turbulence component is reduced, and the pressure fluctuation is reduced, thereby narrowing the venous anastomosis of the graft. Prove that it can be effectively mitigated. Therefore, it is considered that the blood flow control graft (FCG) of this embodiment has great expectation for the improvement of the anastomotic stenosis which is the cause of occlusion of the artificial intravascular shunt, which is a serious clinical problem.

  In short, the suppression of blood flow is effective in reducing anastomotic stenosis for the following reasons. In other words, when a shunt is formed, arterial blood flow suddenly flows into the veins of the arteriovenous shunt. In contrast, veins try to maintain homeostasis. And it is thought that the anastomosis stenosis was caused by it. However, since the blood flow control graft (FCG) of this embodiment suppresses the shunt flow itself as described above, the change applied to the shunt vein is reduced, and the anastomotic stenosis can be reduced. It can be done.

  In terms of material, the E-PTFE graft 1 of this embodiment is also effective in that respect because it has a smooth smooth surface and is unlikely to cause clot obstruction.

  Further, since the moldability is good, it is suitable for integral molding of a seamless structure as shown in FIG.

As described above, according to the present invention, an extracorporeal circuit is formed by being connected between blood vessels of a human body, and a small diameter portion is provided in a part of a conduit, and the whole including the small diameter portion is one continuous. A blood flow control graft formed on a tubular body made of a continuous porous synthetic resin material, the small diameter portion having a cross-sectional shape similar to the cross-sectional shape of the graft conduit, and coaxial with the graft conduit In addition, the inlet side and the outlet side portions thereof are each formed in a funnel shape .

  According to the graft having such a configuration, first, the blood flow is reduced in the narrow diameter portion to suppress the flow rate, and then diffused by the enlargement of the pipe cross-sectional area, resulting in a rectified and gentle flow.

As a result, it is possible to reduce the turbulence of the blood flow flowing in the graft duct , and even when the graft is connected between the artery and the vein, the blood pressure on the vein side is kept low, and the vein wall While avoiding thickening and arterialization, the influence of pulsation based on the difference in compliance between the semi-hardened graft and the compliant vein , i.e., the vibrational stress caused by pulsatile flow is caused between the graft and the vein. The problem of concentrating on the suture line between them can be substantially solved . Its these results, it can be as much as possible effectively prevent the occurrence of a conventional such constriction.

  Such a small-diameter portion can be realized, for example, by deforming the graft into a flat state by sandwiching the graft from the outside with some clamping means, and reducing and changing the pipe cross-sectional area by the clamping.

However, such compressive deformation cannot form a uniform and stable narrow pipe-shaped portion, and even if the passage cross-sectional area can be simply reduced, the flow to the venous side can be appropriately layered. It is not possible to effectively suppress the generation of turbulent flow. Rather, the turbulence is increased by the line shape changes, or even potential to is rather grow stenosis.

  In addition, fatigue and damage of the graft itself become a problem due to repeated compressive deformation. Therefore, a high elastic modulus of the graft material is also required, and the material is limited.

Furthermore, since an external device such as a clamping means is required, the cost is significantly increased accordingly.

However, if the present invention, since the fixedly small diameter portion in a part of the conduit of the graft itself is adapted to be provided, the structure is simple, pipe shape with a constant, or more narrow There is no problem like wearing type.

In the configuration of the present invention, the upper Kigu rafts whole including the small-diameter portion is characterized in that it is formed integrally with the successive pipes of one.

Therefore , compared to the type in which a separate small diameter tube is partially joined and integrated, the inner peripheral surface of the conduit in the graft becomes a continuous smooth surface without a stepped portion, and blood is more It will flow smoothly. Therefore, adhesion of thrombus and the like does not occur.

  In addition, the seamless structure has a high overall strength and excellent safety.

In particular, in the case of the present invention, the graft itself is made of a continuous porous synthetic resin material, which is very smooth in terms of material and has a smooth smooth surface and is less prone to thrombus closure. Is.

Furthermore, since the moldability is good, it is suitable for integral molding of the seamless structure.

In the configuration of the present invention, the upper KiHoso diameter portion forms a cross-sectional shape and similar cross-sectional shape of the graft conduit, that provided in the graft conduit coaxially.

  According to such a configuration, the blood flow that flows from the upstream side of the small-diameter portion to the downstream side of the small-diameter portion becomes a concentric continuous flow throughout, and more effectively suppresses the turbulence. The rectifying effect is increased.

Therefore, the superiority is much higher than when the graft is compressed and deformed by using the external clamping means described above.

In addition, the configuration of the present invention is characterized in that, in the above-described configuration, the inlet side and the outlet side portions of the narrow-diameter portion each have a funnel shape.

  Therefore, according to the same configuration, first, the flow can be smoothly reduced on the inlet side of the small diameter portion, and a more stable reduced flow can be obtained. On the other hand, Karman vortices at the downstream outlet portion are less likely to occur. Thus, the above-described turbulent flow suppression and rectification effects are improved.

Further, in this invention, the small diameter portion, is characterized in that is provided with a predetermined length in the pipe length direction.

According to such a configuration, it is possible to flow in a desired contracted state within a desired time, a more stable contracted flow can be obtained, and turbulent flow suppression and rectification effects are further improved.

Further, the present invention is characterized in that a reinforcing cover having a sleeve structure made of a continuous porous synthetic resin material is fitted to the outer peripheral portion of the small-diameter portion.

According to such a configuration, the graft having the small-diameter portion is configured as a continuous tube having an equal diameter as a whole by fitting a reinforcing cover having a sleeve structure made of the same continuous porous synthetic resin material. The rigidity of the same small diameter part is improved. For example, even when configured and used as a dialysis shunt, etc., an appropriate bending shape (loop shape) is realized as a whole without partial excessive bending. Blood will flow smoothly.

  As a result, according to the present invention, an effective graft capable of effectively suppressing the occurrence of stenosis as in the prior art can be provided at low cost.

  Therefore, it is effective as a shunt for blood purification therapy and other various shunts.

(Configuration of dialysis shunt)
Therefore, the blood flow control graft 1 of this embodiment is interposed between the artery A and the vein V between the upper arm portion 13a and the forearm portion 13b of the human arm 13, as shown in FIG. 4, for example. The present invention is effective even when configured as a dialysis shunt, and can improve the conventional clinical problem (low value of primary patency of postoperative graft) as much as possible.

  In FIG. 4, reference numeral 1 denotes a graft, 2 denotes a narrow-diameter portion, 11 denotes an artery-side anastomosis portion of the graft 1, and 12 denotes a vein-side anastomosis portion of the graft 1.

(Best Mode 2)
Next, FIG. 5 shows a configuration of a blood flow control graft according to the second preferred embodiment of the present invention.

  In this embodiment, the narrow-diameter portion 2 in the configuration of the above-described best embodiment 1 is formed by an independent member 1c separate from the long graft 1, and the outer sides of the funnel portions 2b, 2b on both ends thereof are formed. The ends are formed to have an equal diameter, and the outer ends are connected and integrated into the ends of the two front and rear grafts 1A and 1B, and the same reinforcing cover 3 is fitted to the outer periphery thereof. It is characterized by the combination.

  Even with such a configuration, it is possible to obtain the same stenosis suppressing effect as that of the blood flow control graft of the first embodiment described above.

(Other embodiments)
Furthermore, in the above embodiment, for example, E-PTFE is adopted as an example of the synthetic resin material for forming the graft 1 and the small diameter portion 2, etc., but other polyurethanes generally used as a current graft material are also used. Other synthetic resin materials can also be used.

It is sectional drawing which shows the structure of the blood-flow control graft which concerns on the best Embodiment 1 of invention of this application. It is sectional drawing which shows the blood flow control effect | action of the graft. It is a figure which shows the animal experiment example which confirmed the effect of the small diameter part at the time of forming a loop-shaped inner shunt between the femoral artery and vein of a dog using the graft. It is a figure which shows an example of the shunt for dialysis comprised using the same graft. It is sectional drawing which shows the structure of the blood-flow control graft which concerns on best Embodiment 2 of invention of this application. It is a figure which shows the example of an animal experiment at the time of forming the loop-shaped inner shunt between the femoral artery and vein of a dog using the conventional graft.

  DESCRIPTION OF SYMBOLS 1 is graft | grafting, 1a is a conduit | pipe inner line, 2 is a narrow diameter part, 2a is an equal diameter part, 2b is a funnel part, 3 is a reinforcement cover, 6 is stenosis, 11 is an arterial side anastomosis part, 12 is a venous side anastomosis part , 13 is an arm, 13a is an upper arm portion, and 13b is a forearm portion.

Claims (3)

Connected between blood vessels of the human body to form an extracorporeal circuit, a small diameter portion is provided in a part of the conduit, and the blood flow formed entirely in one continuous tube including the small diameter portion The control graft is made of a continuous porous synthetic resin material, and the small-diameter portion has a cross-sectional shape similar to the cross-sectional shape of the graft conduit, is provided coaxially with the graft conduit, and the inlet A blood flow control graft characterized by a funnel shape on both sides   The blood flow control graft according to claim 1, wherein the narrow diameter portion is provided with a predetermined length in the tube length direction. 3. The blood flow control graft according to claim 1, wherein a reinforcing cover having a sleeve structure made of a continuous porous synthetic resin material is fitted to the outer peripheral portion of the small diameter portion.

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