Artificial Vascular Prostheses Research Articles

Comprehensive hemocompatibility analysis on the application of diamond-like carbon to ePTFE artificial vascular prosthesis

The aim of this study was to obtain comprehensive data regarding the hemocompatibility of diamond-like carbon (DLC)-coated expanded polytetrafluoroethylene (ePTFE). DLC increased the hydrophilicity and smoothened the surface and fibrillar structure, respectively, of the ePTFE. DLC-coated ePTFE had more albumin and fibrinogen adsorption and less platelet adhesion than uncoated ePTFE. There were scarce red cell attachments in in vitro human and in vivo animal (rat and swine) whole blood contact tests in both DLC-coated and uncoated ePTFE. DLC-coated ePTFE had a similar but marginally thicker band movement than uncoated-ePTFE with SDS-PAGE after human whole blood contact test. In addition, survival studies of aortic graft replacement in rats (1.5 mm graft) and arteriovenous shunt in goats (4 mm graft) were performed to compare the patency and clot formation between DLC-coated and uncoated ePTFE grafts. Comparable patency was observed in both animal models. However, clots were observed in the luminal surface of the patent 1.5 mm DLC-coated ePTFE grafts, but not in that of uncoated ePTFE grafts. In conclusions, hemocompatibility of DLC-coated ePTFE was high and comparable to that of uncoated ePTFE. However, it failed to improve the hemocompatibility of 1.5 mm ePTFE graft probably because increased fibrinogen adsorption canceled the other beneficial effects of DLC.

An in vitro analysis of the effect of geometry-induced flows on endothelial cell behavior in 3D printed small-diameter blood vessels

Clinical recovery from vascular diseases has increasingly become reliant upon the successful fabrication of artificial blood vessels (BVs) or vascular prostheses due to the shortage of autologous vessels and the high incidence of vessel graft diseases. Even though many attempts at the clinical implementation of large artificial BVs have been reported to be successful, the development of small-diameter BVs remains one of the significant challenges due to the limitation of micro-manufacturing capacity in complexity and reproducibility, as well as the development of thrombosis. The present study aims to develop 3D printed small-diameter artificial BVs that recapitulate the longitudinal geometric elements in the native BVs using biocompatible polylactic acid (PLA). As their intrinsic physical properties are crystallinity dependent, we used two PLA filaments with different crystallinity to investigate the suitability of their physical properties in the micro-manufacturing of BVs. To explore the mechanism of venous thrombosis, our study provided a preliminarily comparative analysis of the effect of geometry-induced flows on the behavior of human endothelial cells (ECs). Our results showed that the adhered healthy ECs in the 3D printed BV exhibited regulated patterns, such as elongated and aligned parallel to the flow direction, as well as geometry-induced EC response mechanisms that are associated with hemodynamic shear stresses. Furthermore, the computational fluid dynamics simulation results provided insightful information to predict velocity profile and wall shear stress distribution in the geometries of BVs in accordance with their spatiotemporally-dependent cell behaviors. Our study demonstrated that 3D printed small-diameter BVs could serve as suitable candidates for fundamental BV studies and hold great potential for clinical applications.

Cell and tissue reactions in response to experimental implantation of modified artificial vascular prostheses

Objective. To perform histological evaluation of cell and tissue reactions in response to experimental implantation of various variants of antibacterial modifications of artificial vascular prostheses.Materials and methods. The study of the cell and tissue reactions was carried out on 45 laboratory white rats. Industrially produced samples of textile woven vascular prostheses modified by two types of developed coatings based on a polyvinyl-chitosan complex with the addition of biologically active substances and the antibiotic Vancomycin 1 % were studied. In accordance with the design of the study, the animals were removed from the experiment on the 5th, 14th day and 20th week of the postoperative period by means of decapitation. Samples were taken for histological examination.Results. The study of the cellular composition of tissues along the periphery of the vascular prostheses has showed that the animals of the experimental groups had less pronounced inflammatory reactions compared with the control one on the 5th day of observation. The largest number of cells forming connective tissue fibers was in the samples of the second experimental group (p < 0.05). During the intermediate followup periods (day 14), the inflammatory reaction continued to decrease in the experimental samples and a high rate of formation and maturation of granulation tissue was observed (p < 0.05). The inflammatory productive reaction decreased significantly (p < 0.05) in the samples of the second experimental group compared to the first experimental group. During the late follow-up period (20 weeks), the experimental groups were significantly characterized (p < 0.05) by less severe chronic inflammation reactions and a higher degree of maturation and transformation of granulation tissue into coarse-fibrous one, and a higher content of mature connective tissue cells was determined in the second experimental group compared to the first experimental group (p < 0.05).Conclusion. We have found that the most preferred modifications of textile woven vascular prostheses are antibacterial coatings without polyvinylpyrrolidone, which significantly reduce inflammatory reactions and enhance the fibroplastic properties of the prostheses during all follow-up periods.

Facilitation of adhesion and spreading of endothelial cells on silicone oxide-coated dacron material by microwave-excited low-pressure plasma.

ObjectivesAutologous transplants are still the means of choice for bypass surgery. In addition to good tolerability, there is a reduced thrombogenicity and fewer neointima hyperplasia compared to artificial materials. However, since viable transplants are limited, attempts are being made to improve existing artificial vascular prosthesis material. Next to the reduction of thrombogenicity, a rapid endothelialization of the vascular graft should reduce intimal hyperplasia and thus prevent stenoses. The effect of newly developed silicon oxide coatings on the growth of endothelial cells was therefore the goal of this work in a cell culture study.MethodsA woven, uncoated polyethylene terephthalate (PET) vessel prosthesis was used. The coating process was carried out in a low-pressure plasma reactor in a multi-step process. After preparation of the vacuum chamber hexamethyldisiloxane (HDMSO) with oxygen was evaporated using argon plasma. By this an approx. 1 nm thin adhesion promoter layer was separated from plasma and HMDSO. The silicone oxide barrier layer was applied to the PET vessel samples. The carbon content of the layer could be selectively altered by changing the HMDSO oxygen flow ratio, resulting in coatings of 100 nm, 500 nm, and 1,000 nm. In addition, two different oxygen-to-HMDSO ratios were used. To achieve a carbon coating as low as possible, the ratio was set to 200:1. A carbon-rich layer was obtained with the 1:1 setting. The various coatings were then examined for their surface texture by scanning electron microscopy (SEM) as well as by cell culture experiments for cell viability and growth using EA.hy 926 cells.ResultsSEM showed no changes in the surface morphology; however a layer thickness of 1,000 nm showed peeled off coating areas. Alamar blue assays showed a significantly higher metabolic activity (p=0.026) for the coating 500 nm, ratio 200:1 compared to untreated control samples and a significantly lower metabolic activity (p=0.037) of the coating 500 nm, ratio 1:1 compared to the coating 500 nm, ratio 200:1. This underlines the apparent tendency of the 1:1 coating to inhibit the metabolic activity of the cells, while the 200:1 coating increases the activity. Fluorescence microscopy after calcein acetoxymethyl ester (AM) staining showed no significant difference between the different coatings and the uncoated PET material. However, a tendency of the increased surface growth on the coating 500 nm, ratio 200:1, is shown. The coatings with the ratio 1:1 tend to be less densely covered.ConclusionsThe results of this work indicate a great potential in the silicon coating of vascular prosthesis material. The plasma coating can be carried out easy and gently. Cell culture experiments demonstrated a tendency towards better growth of the cells on the 200:1 ratio coating and a poorer growth on the carbon-rich coating 1:1 compared to the uncoated material. The coating with silicon oxide with a thickness of 500 nm and an oxygen-HMDSO ratio of 200:1, a particularly low-carbon layer, appears to be a coating, which should therefore be further investigated for its effects on thrombogenicity and intimal hyperplasia.

КЛИНИКО-ДЕМОГРАФИЧЕСКАЯ ХАРАКТЕРИСТИКА ПАЦИЕНТОВ И ФАКТОРЫ РИСКА ИНФИЦИРОВАНИЯ ИСКУССТВЕННЫХ СОСУДИСТЫХ ПРОТЕЗОВ ПОСЛЕ РЕКОНСТРУКТИВНЫХ ОПЕРАЦИЙ НА АОРТО-ПОДВЗДОШНО-БЕДРЕННОМ СЕГМЕНТЕ

Objective: to study the clinical and demographic characteristics of patients and risk factors, to analyze their influence on the frequency of infection of artificial vascular prostheses in the aortoiliac-femoral segment. Material and methods. We analyzed 609 medical records of inpatient patients who had undergone vascular reconstructive interventions on the aortoiliac-femoral segment using a synthetic vascular prosthesis. The article presents the clinical and demographic characteristics of patients with lesions of the aortoiliac-femoral segment. The frequency of conduit infection in various major diseases, surgical approaches, types of bypass surgery (prosthetics), types of artificial vascular prosthesis was analysed. Results. The patients who developed lesions of the aortoiliac-femoral segment were mostly males (94.6%), urban residents (78%), unemployed (68.6%), those with chronic obliterating diseases of the arteries of the lower extremities (72.7%) and coronary heart disease (59.4%). The incidence of vascular prostheses in patients with chronic obliterating diseases of the arteries of the lower extremities was 5.5%, and in those with an aneurysm of the infrarenal abdominal aorta – 1.2%. Conclusion. The pattern of developing artificial vascular prosthesis infection has been established. Infection of conduits occurs statistically significantly more often in patients with chronic obliterating diseases of the arteries of the lower extremities than in those with an aneurysm of the infrarenal abdominal aorta.

Histological mapping of porcine carotid arteries — An animal model for the assessment of artificial conduits suitable for coronary bypass grafting in humans

BackgroundUsing animal models in experimental medicine requires mapping of their anatomical variability. Porcine common carotid arteries (CCA) are often preferred for the preclinical testing of vascular grafts due to their anatomical and physiological similarity to human small-diameter arteries. Comparing the microscopic structure of animal model organs to their human counterparts reveals the benefits and limitations of translational medicine. MethodsUsing quantitative histology and stereology, we performed an extensive mapping of the regional proximodistal differences in the fractions of elastin, collagen, and smooth muscle actin as well as the intima-media and wall thicknesses among 404 segments (every 1 cm) of porcine CCAs collected from male and female pigs (n = 21). We also compared the microscopic structure of porcine CCAs with segments of human coronary arteries and one of the preferred arterial conduits used for the coronary artery bypass grafting (CABG), namely, the internal thoracic artery (ITA) (n = 21 human cadavers). ResultsThe results showed that the histological structure of left and right porcine CCA can be considered equivalent, provided that gross anatomical variations of the regular branching patterns are excluded. The proximal elastic carotid (51.2% elastin, 4.2% collagen, and 37.2% actin) transitioned to more muscular middle segments (23.5% elastin, 4.9% collagen, 54.3% actin) at the range of 2–3 centimeters and then to even more muscular distal segments (17.2% elastin, 4.9% collagen, 64.0% actin). The resulting morphometric data set shows the biological variability of the artery and is made available for biomechanical modeling and for performing a power analysis and calculating the minimum number of samples per group when planning further experiments with this widely used large animal model. ConclusionsComparison of porcine carotids with human coronary arteries and ITA revealed the benefits and the limitations of using porcine CCAs as a valid model for testing bioengineered small-diameter CABG vascular conduits. Morphometry of human coronary arteries and ITA provided more realistic data for tailoring multilayered artificial vascular prostheses and the ranges of values within which the conduits should be tested in the future. Despite their limitations, porcine CCAs remain a widely used and well-characterized large animal model that is available for a variety of experiments in vascular surgery.

The early days of vascular and heart valve prostheses: a historical review.

This surgical heritage article provides a historical overview of the most important early advances of vascular- and valvular surgery, that lead to the development of currently used vascular- and valvular prostheses and materials. The first writings describing techniques in vascular surgery mainly focussed on hemorrhage control and date from around 1600 B.C. The strategy of vessel ligation was first mentioned in Western literature around 200 B.C. In the 18th century, techniques of ligation were expanded towards attempts of vessel restoration. The first artificial vascular prosthesis was made in 1894. From this time on, vascular prostheses were used in animal experiments and around 1900 for the first time in humans. More than 60 years later, in 1952, the first mechanical heart valve prosthesis was implanted. Four years later, the first successful biological heart valve implantation followed. In 2000, a transcatheter heart valve was successfully implanted in a human for the first time. Over time, procedures and techniques became more efficient and effective. This led to new developments, such as the manufacturing of a tissue engineered blood vessel in 1986. Nowadays, dozens of different valve prostheses have been devised, both mechanical and biological. Still, no ideal model of vascular and heart valve prosthesis exists.

Influence of PEG on heparin release of heparin-loading PCL/PEG vascular prosthesis membranes

Objective To investigate the influence of polyethylene glycol (PEG) on heparin release of heparin-loaded polycaprolactone/polyethylene glycol (PCL/PEG) membranes used in artificial vascular peosthesis. Methods Heparin-loaded PCL/PEG membrane samples with different PEG mass contents of 0, 0.5%, 10% and 15% were prepared by blending method and freeze-drying technology. The influence of PEG on heparin release was experimental studied in vitro. The influence of PEG on the structural characteristics of the samples were investigated by X-ray diffraction, Fourier transform infrared spectrum and differential scanning calorimeter. Results The addition of PEG reduced the heparin release resistance. The results showed that the average release rate of heparin in the first day and the release amount for 34 d were improved. Both these parameters increased with the increase of PEG mass content. The X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry showed that the crystallinity of PCL membrane was slightly enhanced by the addition of heparin, but the overall effect was not significant. In addition, the addition of heparin could promote the crystalline grain growth of PEG, and a common distribution of heparin and PEG in the matrix was observed. Conclusions The heparin release control can be achieved by adjusting the PEG mass content in heparin-loading PCL/PEG membranes prepared by blending method and freeze-drying technology. The proposed samples may have anticoagulant effect, which can be expected to be used as small-diameter artificial vascular prosthesis material. Key words: Heparinization; Blending; Sustained release; Vascular membrane material

Infekcyjne zapalenie wsierdzia z towarzyszącym zakażeniem sztucznej protezy naczyniowej biodrowo-udowej u pacjentki z próchnicą zębów

ENWEndNote BIBJabRef, Mendeley RISPapers, Reference Manager, RefWorks, Zotero AMA Kraśnicka-Sokół B, Kanafa K, Maj E, Bogulas M, Kochmański M. Infective endocarditis associated with artificial iliofemoral vascular prosthesis infection in a patient with caries. Medical Studies/Studia Medyczne. 2015;31(2):129-131. doi:10.5114/ms.2015.52911. APA Kraśnicka-Sokół, B., Kanafa, K., Maj, E., Bogulas, M., & Kochmański, M. (2015). Infective endocarditis associated with artificial iliofemoral vascular prosthesis infection in a patient with caries. Medical Studies/Studia Medyczne, 31(2), 129-131. https://doi.org/10.5114/ms.2015.52911 Chicago Kraśnicka-Sokół, Beata P., Krzysztof Kanafa, Ewa Maj, Monika Bogulas, and Marek Kochmański. 2015. "Infective endocarditis associated with artificial iliofemoral vascular prosthesis infection in a patient with caries". Medical Studies/Studia Medyczne 31 (2): 129-131. doi:10.5114/ms.2015.52911. Harvard Kraśnicka-Sokół, B., Kanafa, K., Maj, E., Bogulas, M., and Kochmański, M. (2015). Infective endocarditis associated with artificial iliofemoral vascular prosthesis infection in a patient with caries. Medical Studies/Studia Medyczne, 31(2), pp.129-131. https://doi.org/10.5114/ms.2015.52911 MLA Kraśnicka-Sokół, Beata P. et al. "Infective endocarditis associated with artificial iliofemoral vascular prosthesis infection in a patient with caries." Medical Studies/Studia Medyczne, vol. 31, no. 2, 2015, pp. 129-131. doi:10.5114/ms.2015.52911. Vancouver Kraśnicka-Sokół B, Kanafa K, Maj E, Bogulas M, Kochmański M. Infective endocarditis associated with artificial iliofemoral vascular prosthesis infection in a patient with caries. Medical Studies/Studia Medyczne. 2015;31(2):129-131. doi:10.5114/ms.2015.52911.

Systemic-pulmonary artery shunts in infants: modified Blalock-Taussig and central shunt procedures.

Access is gained through a midline sternotomy, the thymus partially excised and the superior part of the pericardium is opened. The innominate vein is retracted and the innominate artery is mobilized up to the bifurcation. The aorta is retracted to the left, the superior vena cavae to the right and the right atrial appendage inferiorly. The adventitia around the right pulmonary artery (PA) is dissected, taking care to incise the bulky pericardial reflection between the superior vena cavae and the trachea. Heparin is administrated. An occlusive clamp is applied to the right PA to test for haemodynamic tolerance prior to proceeding with the interposition of a suitable size artificial vascular prosthesis, based on the weight of the patient, between the innominate artery, or proximal subclavian artery and the right PA. Alternatively, if a sufficient main PA is present and adequate flow from a patent ductus arteriosus an end-to-side interposition shunt may be constructed between the ascending aorta and the main PA, provided the patient is stable with the test occlusion of the main PA. The management of the patent arterial ductus depends on whether or not there is forward flow through the PA.

Experimental research on the novel small-caliber vascular prosthesis basing on controlled release of heparin from mesoporous channel

Objective To fabricate the mesoporous-based heparin-loaded expanded polytetrafluoroethylene (ePTFE) vascular prosthesis and evaluate their biocompatibility.Methods The study included the mesoporous-based vascular prosthesis group and the control group.The chromogenic assay.Pressing-perfusion test,protein adsorption assay and lactate dehydrogenase (LDH) cytotoxicity assay were determined to evaluate hemocompatibility and compatibility of vascular prosthesis.Results The heparin-released mesoporous-based vascular prosthesis weas synthesized successfully.The chromogenic assay confirmed that heparin-loaded keep lasting activity than the control vascular prosthesis group (P ＜ 0.05).HMVP-n keep compliance of original vascular prosthesis (P ＞ 0.05).The adsorption of fibrinogen on the surface of HMVP-n membranes is effectively reduced (OD values:0.29 ±0.12,0.31 ±0.06 and 0.30 ± 0.07,respectively),but HMVP-n grafts attracted higher amount of albumin (OD values:0.390 ± 0.150,0.327 ± 0.210 and 0.332 ± 0.240,respectively) compared than unmodified ePTFE graft (P ＜ 0.05),HMVP-1 especially.there was not significant difference of A values between HMVP-n and unmodified material (P ＞0.05) by LDH Cytotoxicity Assay.Conclusion The heparin-released mesoporous-based vascular prosthesis keep lasting antithrombotic activity and has good biocompatibility. Key words: Expanded polytetrafluoroethylene; Artificial vascular prosthesis ; Mesoporous ; Heparin; Biocompatibility

Nursing care of endovascular aneurysm repair patients

The treatment of aortic disease previously used conventional open surgery to replace the aorta with artificial vascular prosthesis after resecting the lesioned segment. The recently developed technique of endovascular aneurysm repair (EVAR) uses a stent graft to reinforce the diseased aortic wall while allowing blood flow continuity and preventing further aortic expansion, dissection and aortic rupture. Taiwan's National Health Insurance now covers payment for authorized EVAR procedures, making treatments safer for patients who are elderly, have congestive heart failure, have multiple comorbidities, or have other high-risk factors. EVAR is gradually replacing previous methods to become the primary treatment approach for aortic disease. This article discusses the development of EVAR, indications, operative procedures, complications, postoperative risk factors, and clinical nursing problems. We hope that this article provides new information on nursing care for patients undergoing endovascular aneurysm repair surgery.

Enhanced blood compatibility of metallocene polyethylene subjected to hydrochloric acid treatment for cardiovascular implants.

Blood compatibility of metallocene polyethylene (mPE) was investigated after modifying the surface using hydrochloric acid. Contact angle of the mPE exposed to HCl poses a decrease in its value which indicates increasing wettability and better blood compatibility. Surface of mPE analyzed by using FTIR revealed no significant changes in its functional groups after treatment. Furthermore, scanning electron microscope images supported the increasing wettability through the modifications like pit formations and etching on the acid rendered surface. To evaluate the effect of acid treatment on the coagulation cascade, prothrombin time (PT) and activated partial thromboplastin time (APTT) were measured. Both PT and APTT were delayed significantly (P < 0.05) after 60 min exposure implying improved blood compatibility of the surfaces. Hemolysis assay of the treated surface showed a remarkable decrease in the percentage of lysis of red blood cells when compared with untreated surface. Moreover, platelet adhesion assay demonstrated that HCl exposed surfaces deter the attachment of platelets and thereby reduce the chances of activation of blood coagulation cascade. These results confirmed the enhanced blood compatibility of mPE after HCl exposure which can be utilized for cardiovascular implants like artificial vascular prostheses, implants, and various blood contacting devices.

Endothelial Cell Lining of PET Vascular Prostheses: Modification with Degradable Polyester-based Copolymers and Adhesive Protein Multi-layers

Background: Bypass surgery for atherosclerosis is confronted with the absence of endothelial cells in the lumen of vascular prosthesis in humans. This imposes a risk of thrombosis. New biomaterials try to minimize surface thrombogenicity. Methods: Knitted polyethylene terephthalate (PET) vascular graft patches were impregnated with degradable polyester polymers: poly (L-lactide-co-glycolide) (PLG) or poly (L-lactide-co-glycolide-co-e-caprolactone) (PLGC). The luminal surface was coated with collagen type I (Co) to which extracellular matrix proteins laminin (LM), fibronectin (FN), or surface fibrin gel (Fb) were attached. Three types of prostheses (PET, PET–PLG and PET– PLGC) and 5 types of protein assemblies (+Co, +Co/LM, +Co/FN, +Co/Fb, +Co/Fb/FN) were fabricated. Scanning electron microscopy and measurements of the water contact angles were performed. The development of a bovine endothelial cell layer was studied in a static culture for 1 week. Results: The cells reached confluence on all PET surfaces with the highest final density on +Co/FN. Impregnation of PET with polymers made it less adhesive for cells in the following order: PET > PET–PLG > PET– PLGC. However, additional coating with the protein assemblies enhanced the endothelial cell growth, especially on fibrin-containing surfaces. Conclusion: Tri-component vascular grafts composed of PET, copolymers and cell-adhesive assemblies were fabricated. The endothelial lining on the polymer-coated grafts was promoted after modification with the protein multilayers. Artificial vascular prostheses have been made of non-degradable, non-compliant and thrombogenic materials for more than 50 years. Thus, they resemble passive tubing. Potential bio-activation by degradable materials and by introduction of living endothelial cells may approximate these materials to native artery. This work provided a method to include bio-degradable polymers into vascular graft and to facilitate the growth of cell lining via adhesive protein multilayers.

Application of a rotating bioreactor consisting of low-cost and ready-to-use medical disposables forin vitroevaluation of the endothelialization efficiency of small-caliber vascular prostheses

The incomplete endothelialization of especially small-caliber vascular prostheses after implantation in patients is a major disadvantage in cardiovascular interventions. The lack of an endothelium leads to the occurrence of thrombosis at the luminal surface of artificial vascular prostheses. Thus, the development of new graft materials and coatings for induction of complete endothelialization on the implant surfaces is a promising approach to improve hemocompatibility and maintain long-term graft patency. In this study, we designed a rotation model to evaluate the early endothelial cell (EC) seeding efficiency of different small-caliber vascular devices, such as stents and vascular grafts. The suitability of the designed rotation model for endothelialization studies was investigated by seeding and cultivation of prostheses with ECs followed by scanning electron microscopy. Furthermore, the viability of attached ECs was determined by calcein acetoxymethyl ester (AM) staining. The rotation model consisting of low-cost medical disposables enabled sterile incubation and cultivation of ECs with vascular devices. Simultaneously, the rotation of the bioreactor ensured a uniform distribution and adhesion of cells to the devices. Calcein AM staining of adherent cells on prostheses revealed excellent cell viability. Moreover, using the designed rotation model, an influence of different coatings and materials on the adhesion and spreading of ECs was demonstrated. The rotating bioreactor described and used in this study not only saves time and money but is also eminently useful for the accelerated preclinical evaluation of the endothelialization efficiency of different materials and surface coatings of small-caliber vascular devices.

Microwave-Assisted Surface Modification of Metallocene Polyethylene for Improving Blood Compatibility

A wide number of polymers are being used for various medical applications. In this work, microwave-assisted surface modification of metallocene polyethylene (mPE) was studied. FTIR analysis showed no significant changes in the chemical groups after treatment. Contact angle analysis revealed a decrease in contact angle of the treated samples insinuating increasing hydrophilicity and better biocompatibility. Qualitative analysis of treated samples using scanning electron microscope (SEM) depicted increasing surface roughness and holes formation further corroborating the results. Coagulation assays performed for estimating prothrombin time (PT) and activated partial thromboplastin time (APTT) showed an increase in the clotting time which further confirmed the improved blood compatibility of the microwave-treated surfaces. Further, the extent of hemolysis in the treated sample was lower than the untreated one. Hence, microwave-assisted surface modification of mPE resulted in enhanced blood compatibility. Improved blood compatibility of mPE may be exploited for fabrication of artificial vascular prostheses, implants, and various blood contacting devices.

Mechanical properties of biodegradable small‐diameter chitosan artificial vascular prosthesis

Initial clinical feasibility with the small-diameter chitosan artificial vascular prosthesis has been reported previously. Here, we present the results of mechanical properties of artificial vascular prosthesis with 2, 3, and 4 mm inner diameter (ID) and compare some of the properties with the native blood vessel of dog femoral artery. Thickness wall measurement demonstrated the average wall thickness of the artificial vascular prosthesis with 2, 3, and 4 mm ID and the native blood vessel of the dog femoral artery with 3 mm ID were 0.54 ± 0.022 mm, 0.71 ± 0.032 mm, 0.79 ± 0.026 mm, and 0.67 ± 0.22 mm (n = 20). Water absorption rate of 226.02% ± 8.17%, 216.13% ± 4.86%, and 205.69% ± 4.34% were obtained from 2-, 3-, and 4-mm-diameter artificial vascular prosthesis (n = 12), respectively. Water osmotic pressure of the 2-, 3-, and 4-mm-diameter artificial vascular prosthesis was 39.25 ± 3.35 mmHg, 34.2 ± 4.54 mmHg, and 28.00 ± 2.72 mmHg (n = 20), respectively. Water osmotic amount of the 2-, 3-, and 4-cm-diameter artificial vascular prosthesis (n = 20) was 4.90 ± 0.47 mL/(min cm(2) ), 5.51 ± 0.21 mL/(min cm(2) ), and 6.24 ± 0.71 mL/(min cm(2) ), respectively. The ruptured stretching rate of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID and the native blood vessel was 1.59% ± 0.14%, 1.99% ± 0.24%, 2.52% ± 0.21%, and 32.16% ± 2.15%, respectively. The longitudinal tensile strength of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID and the native blood vessel was 8.58 ± 1.98 N, 19.75 ± 4.07 N, 22.92 ± 3.85 N, and 18.76 ± 2.05 N, respectively. The suture retention of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID and the native blood vessel in dry condition is 5.80 ± 0.51 N, 7.01 ± 0.32 N, 8.49 ± 0.56 N, and 7.92 ± 0.39 N, respectively. The suture retention of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID in wet condition is 3.87 ± 0.43 N, 4.73 ± 0.37 N, 5.63 ± 0.36 N, and 7.92 ± 0.39 N, respectively. The compliance of the artificial vascular prosthesis with 2, 3, and 4 mm ID and the native blood vessel was 6.5% ± 2.6%/100 mmHg, 5.2% ± 1.5%/100 mmHg, 4.7% ± 1.3%/100 mmHg, and 10.3% ± 2.3%/100 mmHg, respectively. The data reported here fulfill the quality requirement of clinical use of this kind of biodegradable small diameter artificial vascular prosthesis.

New biodegradable small-diameter artificial vascular prosthesis: A feasibility study

An in-house built instrument was used to fabricate a small internal diameter (2 mm) artificial vascular prosthesis from biodegradable chitosan. This new artificial vascular prosthesis has shown a good biocompatibility based on the studies of its cell compatibility, inflammatory reaction, and platelet adhesion. In an animal test, the prosthesis was used to replace a 4-cm-long section of femoral artery in each of the seven tested dogs. The patency of the replacement was monitored at regular intervals using Doppler ultrasound diagnostics. Nine months after the implantation, hematoxylin and eosin staining, immunohistochemical study, and scanning electron microscope observation were carried out. Complete decomposition of the prosthesis and replacement by a natural blood vessel were observed. The results suggests that the artificial vascular prosthesis displays many characteristics of the "ideal" small-diameter artificial vascular, and have the biocompatibility that can be tailored to match those desired in vascular replacement application.

An in vitro rotation model composed of disposables for investigation of endothelialization of artificial vascular prostheses

Objectives: The incomplete endothelialization of mainly small caliber vascular prostheses is a major drawback in cardiovascular surgeries. The lack of an endothelium leads to the occurance of thrombosis at the luminal surface of artificial vascular prostheses. The generation of a fully functional endothelium on the surface of blood contacting devices is a promising approach in terms of the improvement of hemocompatibility and the maintenance of long term graft patency. We present a low-cost in vitro rotation model composed of disposables for investigation of endothelialization of artificial surfaces.

MORHOLOGICAL AND FUNCTIONAL ASPECTS OF THE APPLICATION OF FEMORAL VEINS FOR AORTOILIAC RECONSTRUCTION IN EXPERIMENT

The aim of the study. To study the functional adequacy of different vascular conduits. Material and methods. The morphological and functional qualities of femoral vein in comparison with those of superficial vein and artificial prosthesis in 12 pedigreeless male dogs weighted 15,3 ± 3,7 kg have been studied. All the dogs underwent ilio-femoral bypass with combined conduit, sewn from the fragments of femoral vein, superficial vein and polytetrafluorinethylene vascular prosthesis. The specimens were obtained in the interval of 3, 6, 9 and 12 months. Mann-Whitney`s U-criterion, a non-parametric method for comparison of two independent samples was applied to compare the quantities that are not subject to Gauss` distribution. Results and discussion. The apex of morphological-functional rebuilding of veins, caused by their involvement in arterial flow, seems to appear in the interval from 3 to 6 months since the implantation. The changes of femoral vein occur earlier then those of subcutaneous vein. The dystrophic signs are less expressed in femoral vein. The morphological-functional properties of femoral vein differ from those of superficial vein. A peak of regenerative processes on the surface of the artificial vascular prosthesis falls on the term of 6 months. The later termed involutive processes prevail over the regenerative processes.