Artificial blood vessels are substitutes for many severely stenotic or occlusive vessels, which are mostly made of synthetic materials such as nylon, Dacron, PTFE, etc. They are suitable for vascular bypass surgery throughout the body. Large and medium caliber artificial blood vessels have been used in clinical practice with satisfactory results.
On November 17, 2022, the State Food and Drug Administration announced the approval of the innovative product "artificial blood vessel" produced by Jiangsu Baiyouda Life Technology Co., LtdRegistration.[2]
Cardiovascular disease is one of the common diseases endangering human health. The main and auxiliary treatment for patients with serious cardiovascular disease is vascular transplantation, and the source of autologous blood vessels is limited. Therefore, a large number of artificial blood vessels are needed as transplant substitutes in clinical practice.
When the blood vessel in the human body ruptures, the artificial blood vessel made of polyester material can be transplanted, but because the blood is easy to solidify on the inner wall of the artificial blood vessel, if the artificial blood vessel is too thin, it is easy to block, which has always been a difficulty in developing artificial blood vessels.
development history
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The manufacture of artificial blood vessels, foreign research, the vast majority of medical polymer materials for weaving.In the late 1950s and early 1960s, China began to carry out research. At first, it was woven from nylon, but later it was eliminated due to the degradation of nylon, which broke after implantation in vivo.Dacron fiber woven artificial blood vessels have been widely used in clinical practice, such as the treatment of aortic lameness, aortic stenosis, superior and inferior vena cava resection and replacement.
In November 2015, the National Research Center of Circulatory Organs of Japan announced that its researchers had successfully developed artificial blood vessels with a diameter of only 0.6 mm.This is the world's finest artificial vessel, which is expected to be used in brain and heart bypass surgery and other fields.[1]A research team in the center used the nature that collagen would wrap foreign bodies entering the body when they encountered them. They implanted a stainless steel wire with a diameter of 0.6 mm and a length of 2 cm covered with silicon into the back of the rat subcutaneously. About two months later, they took it out, and found a tube of collagen around the stainless steel wire.After transplanting the tube into the thigh of experimental rats, the researchers observed it for about six months and found that it played the role of artificial blood vessels.
Weaving mode
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There are two kinds of machine woven artificial blood vessels: one is weaving, also known as weaving, and the other is knitting, also known as loop weaving.
(1) Flat knitting is to use warp and weft for knitting. The warp fibers interact up and down, and the weft fibers shuttle horizontally from left to right.The fabric has compact fibers, rich extensibility, fine and small porosity, but its broken end is easy to loose, in the shape of a brush, hard and difficult to sew.
(2) Knitting is usually carried out on a weft knitting machine, and weft knitting can also be carried out on a round machine, using filaments as loops or interlock knitting.The fabric has poor extensibility, large porosity, soft texture, and its broken end is not easy to loosen and is easy to sew.In addition, warp knitting has more layers than weft knitting, so the fiber is more compact and less loose.At present, polyester and polytetrafluoroethylene are widely used as artificial blood vessel materials, and knitted artificial blood vessels are used.
Applicable conditions
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For the artificial blood vessel woven by machine, the minimum inner diameter of plain weave is 8 mm, and the inner diameter of knitting is 3 mm.In addition, there are artificial blood vessels woven from expanded polytetrafluoroethylene fiber materials, with an inner diameter of 6 mm.Recently, it was reported abroad that the artificial blood vessel made of elastic polyurethane has no pores in the wall, smooth inner wall, and can stretch with the change of blood pressure. The inner diameter can reach 4 mm. The artificial blood vessel made of this material is very promising.
Illustration
(1) The artificial blood vessels with a diameter of 18~24 mm can be used for the replacement of thoracic aorta.
(2) The Y-type artificial vessel with a diameter of 16~20 mm * 8 mm can be used for the artificial vessel bypass of the abdominal aorta, double iliac (femoral) arteries, and the artificial vessel bypass of the ascending aorta double neck (or double subclavian) arteries.
(3) The artificial blood vessels with a diameter of 6~10 mm can be used for the artificial blood vessel bypass of the arteries of the limbs and the neck arteries.
(4) Conical vessels with a diameter of 6-8 mm (8 mm at one end and 6 mm at the other end, a gradual decline process) can be used to improve the anastomotic difficulty caused by different diameters of autologous blood vessels at both ends when the length of artificial blood vessels in limbs (especially lower limbs) is converted.
Application
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(1) Artery disease: It is used to replace or bridge (vascular bypass surgery) to restore blood access to treat thoracic aorta, abdominal aorta, iliac artery and other vascular segments.Arterial disease, such as arterial embolism or aneurysm.
(2) Venous disease: It can replace or bridge (vascular bypass surgery) to treat venous diseases, such as Budd Chiari syndrome.
(3) Arteriovenous fistula: it can be used in the hemodialysis process of chronic kidney disease to connect the arteries and veins of the limbs to form a repeatable hemodialysis access.
Other blood vessels
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Carbon coated blood vessel
The carbon atoms evenly embedded in the inner wall of the blood vessel are organically integrated with the blood vessel wall, and have no reaction with the tissue.The weak negative charge of the carbon coating repels platelet deposition on the tube wall, effectively reducing thrombosis;Carbon coating is not conducive to the growth and dissemination of smooth muscle cells, reduces interstitial hyperplasia, and can significantly improve the vascular patency rate.
Biological hybrid artificial blood vessel
In order to improve the adaptability of artificial blood vessels woven with synthetic materials to biological organisms, a layer of biomaterials is coated on the surface of these polymer materials, which is called biological hybrid artificial blood vessels.The artificial coatings generally applied include the following: albumin, which can improve the anticoagulant performance of artificial blood vessels;Fibronectin can promote the formation of intima, and then inhibit the occurrence of coagulation;Collagen can promote the formation of intima, prevent coagulation, and improve the compliance of artificial blood vessels;Gelatin, with the function of promoting cell adhesion and growth, can induce the formation of intima after implantation and prevent coagulation.
Sleeve vessel
The sleeve shaped vessels are designed by a special sleeve shaped three-dimensional computer model to optimize the hemodynamics of the outflow tract, reduce intimal hyperplasia at the anastomosis, and significantly increase the patency rate.The inner membrane is coated with carbon to reduce platelet deposition.
