[Effect of different vascular prosthesis materials on blood platelets, blood clotting and fibrinolysis]. / Wplyw tworzyw róznych typów protez naczyniowych na plytki krwi, uklad krzepniecia i fibrynolize.

Studies were performed on Dacron vascular prostheses (USA), Gore-Tex (Germany), polyester prostheses (Czechoslovakia), Lawsan (Russia), as well as on DALLON-standard and DALLON-double velour prostheses (Poland), non-impregnated or impregnated with collagen, with heparin and albumin, with antithrombotic and antibacterial preparation, and with antibacterial preparation. In vitro, all the materials of vascular prostheses cause an adhesion of platelets in different degree, increase the availability of platelet factor 3, release platelet factor 4, reduce the blood clot retraction, shorten clotting time of the whole blood as well as recalcination time of intact plasma and increase the prothrombin consumption. None of the materials induced platelet aggregation nor influenced the activity of fibrinolytic system. Prostheses impregnated with collagen or with heparin and albumin were the most thrombogenic. Those impregnated with antibacterial preparation or with antibacterial and antithrombotic preparations, and Gore-Tex prostheses showed the lowest thrombogenicity. Thrombogenicity of vascular prostheses not only depends on chemical structure of the material, but on the method of fibre manufacturing by individual producers as well.

[Changes in the activity of the clotting system and fibrinolysis components in the layers of double velour DALLON grafts at different periods after implantation into the aorta]. / Zmiany aktywnosci skladników ukladu krzepniecia i fibrynolizy w warstwach przeszczepów DALLON-dwustronny welur w róznym czasie po wszczepieniu do aorty.

During one year experiment, the thromboplastic, antiheparin, plasminogen activator, antithrombin and antiplasmin activities were evaluated in the homogenates of the intimal, medial and adventitial layers of polyester double velour DALLON prostheses implanted into the dog abdominal aorta. It was found, that 7 days after implantation the thromboplastic, antiheparin and plasminogen activator activities in DALLON graft neointima were high, whereas those of the antiplasmin and antithrombin were low. These changes facilitate the sealing of the prosthesis pores and at the same time prevents thrombosis. Four months after implanting, the activity of hemostatically active components in the various graft layers became similar to the activity of aorta components. Rapid decrease of the thrombogenic potential and increase of the fibrinolytic activity in layers of double velour DALLON grafts facilitate the maintenance of graft patency.

[Comparison of healing characteristics of DALLON-standard and DALLON-double velour vascular prostheses]. / Porównanie procesów wgajania sie protez naczyniowych DALLON-standard i DALLON-dwustronny welur.

By means of histological method and the scanning and transmission electron microscope healing processes of two types of Polish prostheses: DALLON-standard and DALLON-double velour were compared. The experiments were carried out on 36 dogs. The two types of prostheses mentioned were implanted in abdominal aorta. The grafts were removed 1, 4 and 12 months after implantation. The performed studies showed that although the sequence and nature of morphological changes leading to the reconstruction of the vascular wall in both types of grafts were similar, the development of the neointima as well as the formation of the neo-adventitia firmly accreted with surrounding tissues were considerably faster in double velour DALLON prostheses. Unlike in standard DALLON prostheses, the neointima of double velour DALLON grafts was rich in cells, had elastic fibres. Already after 12 months double velour DALLON grafts were completely covered by endothelial cells, which proves better reconstruction of the vascular wall. Rapid endothelial cells coverage of the lumen surface prevents thrombosis. Morphological differences observed in endothelial cells covering the neointima of standard grafts and double velour graft suggest the existance of various sources of endothelialization in both types of grafts.

[Comparison of cathepsin D activity of DALLON-standard and DALLON-double velour grafts implanted into the abdominal aorta]. / Porównanie aktywnosci katepsyny D prezeszczepów DALLON-standard i DALLON-dwustronny welur wszczepionych w aorte brzuszna.

Cathepsin D activity was compared during the healing period of polyester DALLON-standard and DALLON-double velour prostheses implanted into the abdominal aorta of dogs. During first months following the implantation cathepsin D activity is considerably higher in all the layers of both types of prostheses than in the aorta. The normalization of this enzyme activity occurs significantly faster during the healing of DALLON-double velour prostheses than in that of DALLON-standard. This fact shows greater progress in the protein metabolism normalization during the process of healing and tissue reconstruction in DALLON-double velour prostheses.

[Content and distribution of collagen in aorta double velour DALLON grafts]. / Zawartosc i rozmieszczenie kolagenu w przeszczepach aortalnych DALLON-dwustronny welur.

The aim of the study was to determine the collagen content, distribution and quantitative ratios between main types of collagen (found in normal vascular walls) in various layers of double velour DALLON grafts at different periods after implantation. Double velour DALLON prostheses were implanted into the abdominal aorta of 24 dogs. These grafts were excised 7 days, 1, 4 and 12 months after implantation and together with normal arteries, after dissection into intimal, medial, and adventitial layers, tested for their hydroxyproline content. Type I, III, V collagen was also determined (fractionation of pepsin digestion products). Already 7 days after implantation collagen appeared in all the newly-formed layers of the grafts. With the passage of time after the operation collagen content was gradually increasing. After 12 months collagen content in the intimal and adventitial layers was significantly higher than in normal arterial wall. Approximate quantitative ratio between collagen types I, III and V in all graft layers was 7:2:1 and did not change during the 1-year-observation. Rise in collagen content results in graft wall stiffening, and the presence of III type collagen increased platelet-aggregating activity. Both these factors created a tendency to the formation of thrombosis in the graft.

[Polish vascular prosthesis sealed by albumin]. / Polskie protezy naczyniowe uszczelniane albumina.

TRICOMED, Medical Articles has been conducting its research on textile vascular prostheses for over 35 years. In the seventies, a collagen coated graft was designed and fabricated which, however, after having been positively evaluated ceased to be used by clinics. In the eighties, double velour DALLONR prostheses was introduced which are now marketed by our company. The DALLONR graft has a low mass, developed surface area and moderate porosity. In the eighties, foreign manufacturers launched various types of coated grafts. Responding to that popular market trend we have resumed our early research on the preclotted prostheses and started studies on the use of albumin and chitosan as coating agents. The grafts impregnated with albumin have achieved satisfactory results of biological and experimental testing. These results are confirmed by current clinical examination.

Polish vascular prostheses.

Vascular prostheses have been manufactured in Poland since 1960. Double velour crimped tube and bifurcation prostheses are currently available under the Trade Mark Dallon. The Authors present and discuss 812 grafting procedures for the aorto-iliac occlusive disease with the use of 457 Polish and 355 foreign-made vascular prostheses. Wound infection occurred in 7% of the patients with implanted Polish prostheses and in 6.8% of the patients with implanted foreign-made vascular grafts. The acute thrombosis of the operated artery was similarly frequent in case of Polish and foreign-made prostheses implantation, 7% and 6.8% respectively. Haemorrhagic complications were more frequent in patients with implanted Polish prostheses (1.7%) than those with foreign-made vascular grafts (0.8%). Early results of the grafting procedures (6-month follow-up) were nearly the same in both groups and the results reported in the available literature. The Authors conclude that the Polish knitted vascular prostheses have properties similar to the foreign-made ones.