Edwards lifesciences

In 1956, Miles Lowell Edwards built the design of the first artificial heart . Having experience in the field of hydraulics and the operation of the fuel pump , he believed that the heart can be mechanized. He introduced this idea to Albert Starr , a young surgeon from the Oregon University of Health and Science who found her too complicated. Instead, Starr encouraged Edwards to initially focus on developing an artificial heart valve (ICV), which was an urgent need. Two years later, the first Starr-Edwards mitral valve was designed, developed and tested at Edwards Laboratories ( Santa Ana , California , near the corporate headquarters of Edwards Lifescience), and was successfully implanted to the patient on August 25, 1960 ^[2] .

The structural features of these prostheses were a plastic saddle and four limiters of the course of the silastic ball made of methyl methacrylate , connected at the top of the prosthesis. The cuff of attachment in the first models was a double silicone disk worn on a fibrous ring ^[2] . In later models, the locking ball was either molded of silicone or hollow of stellit (stellit-21), the support ring and travel stops were made of titanium, the sewn-on cuff was made of Teflon fabric. In 1962, the same developers proposed an aortic valve, distinguished by the number of titanium ball stroke limiters - there were three of them, according to the number of commissures in the area of ​​which they were located during fixation. At the same time, three stops appeared in the lumen of the saddle, which allowed the use of locking elements of a smaller diameter, while maintaining the tightness of the passage opening. Since 1965, sheathing of the support ring with a porous synthetic fabric was introduced.

In subsequent years, the company continued to work on mechanical heart valves, following the general trend of their development. She proposed two models of small - sized valves for the mitral position, produced in 1970-1976. The first of them ( Starr — Edwards 6500 ) used a disk made of Stellite-21 alloy, the case and four intersecting restrictive posts were made of the same alloy, the sewn cuff was Teflon . Along the perimeter of the base of the prosthesis, ellipsoidal holes were made to accelerate implantation into the patient's fibrous ring. Another model ( Starr — Edwards 6520 ) was distinguished by a disk made of high molecular weight polyethylene with a titanium ring included in it.

In 1990, the Italian company Sorin Biomedica began production of Sorin Bicarbon butterfly valves . She combined curved pyrolytic carbon leaflets with a titanium body covered with a carbon film to reduce the thrombogenicity of the prosthesis. This decision simplified the technology for the production of the hull. The sewn-in cuff made of double velor polytetrafluoroethylene also has a carbon coating. The opening angle of the valve is 80 °, the flaps and the body are radiopaque . Curved sashes ensure the equality of the three passage openings of the valve. In addition, the suspension hinge mechanism is designed so that it passes an insignificant reverse blood flow near the suspension devices (leaflet “ears”), helping to “flush” this area and reduce the risk of thrombosis even in the closed position of the valve ^{[3] [4] [5]} .

Edwards Lifesciences acquired the right to release this valve in the USA under the Edwards Mira brand, while retaining the overall valve design, changed the sewing cuff to a lighter one and having silicone inserts to facilitate implantation, and used other materials: the body was made of Pyrolytic coated Stellite alloy carbon ; curved leaves - made of graphite with impregnation with tungsten and a coating of pyrolytic carbon ; sewn cuff - from dacron with or without carbon coating ^[6] . However, the prosthesis was soon discontinued due to registration of cases of tearing off the sash. The reason was the increased microporosity of the material and cavitation damage. After improving the cuff shock absorber when closing the wings and improving the quality of control over the manufacturing process, the valve was returned to the market.

Carpentier — Edwards Bio Valves

In 1975, the company with the participation of Alan Carpentier proposed a Carpentier — Edwards framework bioprosthesis design for intra-implant implantation. The bioprosthesis is treated with a 0.625% solution of glutaraldehyde at high pressure (20 mmHg) and mounted on a flexible wire frame made of a radiopaque cobalt-chromium-nickel alloy to reduce shock loads during closure. Additionally, biological tissue is treated with phospholipid- reducing calcification protection (XenoLogiX). The difference in the frame is three U-shaped wire racks. The aortic version is asymmetric to reduce the stenotic effect of the muscle base of the right coronary valve. The ratio of the valve opening area in the open state to the landing area is 0.76. The sewing cuff of porous Teflon tissue with an insert of silicone rubber is flat for the mitral valves and wavy for the aortic ones (this allows you to adapt the base of the prosthesis to the shape of the recipient's fibrous ring during implantation). With equal strength and wear resistance with Hancock models, this model has a more convenient for implantation design of the case and sewing cuff, and remains available to this day ^{[7] [8]} .

In order to improve hemodynamic efficiency (increase the passage opening area by 20%), bioprostheses for supraannular implantation were developed in the 1980s - mitral Carpentier — Edwards Duraflex (model 6650) and aortic Carpentier — Edwards SAV (model 2650). In them, in order to preserve the natural structure of the valve and the corrugation of the collagen of the valves, treatment with glutaraldehyde at a low pressure of 2 mm Hg began to be used. Art. The height of the frame was reduced, and its cylindrical shape was replaced by a conical one . According to clinical observations, within 5 years after implantation, 84% of patients were free from valve-dependent complications. The disadvantages include the danger of prosthesis dysfunction during implantation into the narrow aortic root after the slightest deformation of the framework of low rigidity ^{[9] [10]} .

In the early 1980s, trials of a pericardial bioprosthesis made from bovine pericardium on a radiopaque framework similar to the Carpentier-Edwards xeno-aortic prosthesis were completed. Structural stabilization of the valve with glutaraldehyde was carried out according to the stress-free method, XenoLogiX treatment was used to prevent calcification . The flaps were attached to a silicone rubber insert containing Teflon sheathing. The pericardial bioprosthesis and at small landing diameters (19 and 21 mm) had good hemodynamics and occupied a significant part of the bioprosthesis market (about 40% in the USA). The absence of its structural degeneration was 99%, 94%, 77% by the 5th, 10th and 15th year after the operation, respectively ^{[11] [12] [13] [14] [15]} .

In 2000, the company announced a modification of the pericardial prosthesis, called Carpentier — Edwards PERIMOUNT . Model 6900P ( mitral ) is available with a flat cuff, models 2700 and 2800 ( aortic for supraannular implantation) - with a wave-like. From the initial version, the prosthesis is distinguished by a low-profile flexible frame made of cobalt-chromium-nickel alloy and treating the silicone cuff with Teflon to reduce thrombogenicity and improve the implantation of the prosthesis in the tissue ^{[16] [17] [18]} .

A special achievement of the company was the development of the Edwards SAPIEN family of heart valves, implantable through a procedure called transcatheter aortic valve replacement (TAVR). This procedure allows the installation of folding heart valves made of bovine tissue inside a collapsible stainless steel stent, which can be introduced into the body through various access pathways to the catheter and advanced to the heart. This occurs through incisions in the leg (transfemoral), between the ribs or above the front of the chest through a small hole in the aorta (transaortic) ^{[19] [20]} .

Implants for the reconstruction of the heart valve, the so-called annuloplasty rings, have also been developed, which are used by surgeons to clamp the patient’s heart valve and allow him to return to its original form ^[21] .

The company also manufactures vascular therapy products and hemodynamic monitors for measuring cardiovascular performance during surgery and intensive care. Such monitoring allows you to measure blood circulation and heart function, and allows doctors to evaluate the adequacy of oxygen delivery to organs and tissues.

Other company products include a Swan-Ganz catheter. Originally developed for patients with acute myocardial infarction, it is currently used in anesthesia and intensive care units. This monitoring is used to obtain information about changes or health problems of the patient, to identify them and make decisions during treatment.

To simplify the procedures in cardiac surgery through small incisions, the company offers a line of products for soft tissue retractors, with venous and arterial cannulas , aortic occlusion device, catheters for ventilation and coronary sinus, as well as reusable instruments to perform minimally invasive procedures on the heart valve.

• Orlovsky P.I., Gritsenko V.V., Yukhnev A.D., Evdokimov S.V., Gavrilenkov V.I. Artificial heart valves. - St. Petersburg: OLMA Media Group, 2007 .-- 448 p. - 1,500 copies - ISBN 978-5-373-00314-8 .