BACKGROUND: Studies comparing alternative autologous vein grafts (AAVGs) to single-segment great saphenous vein (ssGSV) grafts report mixed results. The status of AAVG as first choice when ssGSV is unavailable is not unequivocal based on current evidence. Our study compares results between AAVG and ssGSV in lower extremity bypass (LEB) surgery. METHODS: A single-center retrospective cohort study involving all patients who underwent infrainguinal bypass using AAVG (arm veins, spliced arm, or arm-leg veins) and ssGSV from April 2019 to June 2023. Study endpoints were patency rates and amputation-free survival (AFS). RESULTS: There were 65 (20.8%) patients in the AAVG group, 247 (79.2%) in the ssGSV group. Chronic limb-threatening ischemia (CLTI) was the most frequent indication for surgery (AAVG 54/65, 83.1% vs. ssGSV 170/247, 68.8%), followed by acute limb ischemia (ALI) (AAVG 6/65, 9.2% vs. ssGSV 28/247, 11.3%); claudicants were presented only in the ssGSV group (AAVG 0/65, 0% vs. ssGSV 44/247, 17.8%). More redo operations occurred in AAVG than in the ssGSV group (23/65, 35.4% vs. 26/247, 10.5%; P < 0.001). Spliced vein grafts represented 87.7% (57/65) of AAVG bypasses. The median follow-up was 20.1 months for the AAVG group and 27.5 for the ssGSV group. Three-year patency rates between AAVG versus ssGSV: primary patency (PP) 59.3% ± 8.2% versus 69.2% ± 3.8%, P = 0.113; primary assisted patency (PAP) 75.2% ± 7.1% versus 73.5% ± 3.4%, P = 0.790; secondary patency (SP) 74.9% ± 7.1% versus 74.4% ± 3.4%, P = 0.667; did not display significant difference between groups nor did 3-year AFS in CLTI patients; 70.7% ± 7.9% versus 54.6% ± 4.8%; P = 0.273. CONCLUSION: AAVGs should be the first conduit choice when ssGSV is unavailable. Mid-term patency rates do not differ from those of ssGSV grafts despite higher reintervention rate.

• MeSH
• amputace MeSH
• autologní transplantace MeSH
• časové faktory MeSH
• dolní končetina * krevní zásobení   MeSH
• ischemie * chirurgie   patofyziologie   diagnostické zobrazování   MeSH
• lidé středního věku MeSH
• lidé MeSH
• okluze cévního štěpu patofyziologie   etiologie   chirurgie   MeSH
• onemocnění periferních arterií * chirurgie   patofyziologie   diagnostické zobrazování   mortalita   MeSH
• průchodnost cév MeSH
• retrospektivní studie MeSH
• rizikové faktory MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• transplantace cév * škodlivé účinky   MeSH
• vena saphena * transplantace   patofyziologie   MeSH
• výsledek terapie MeSH
• záchrana končetiny MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH

Residual stresses are considered as a significant factor influencing the stress-states in arteries. These stresses are typically observed through opening angle of a radially cut artery segment, often regarded as a primary descriptor of their stress-free state. However, the experimental evidence regarding the stress-free states of different artery layers is scarce. In this study, two experimental protocols, each employing different layer-separating sequences, were performed on 17 human common carotid arteries; the differences between both protocols were found statistically insignificant. While the media exhibited opening behaviour (reduced curvature), a contrasting trend was observed for the adventitia curvature, indicating its closing behaviour. In addition to the different bending effect, length changes of both layers after separation were observed, namely shortening of the adventitia and elongation of the media. The results point out that not all the residual stresses are released after a radial cut but a significant portion of them is released only after the layer separation. Considering the different mechanical properties of layers, this may significantly change the stress distribution in arterial wall and should be considered in its biomechanical models.

• MeSH
• arteria carotis communis * fyziologie   MeSH
• arteriae carotides * fyziologie   MeSH
• biomechanika MeSH
• lidé středního věku MeSH
• lidé MeSH
• mechanický stres * MeSH
• senioři MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Collagen fiber arrangement is decisive for constitutive description of anisotropic mechanical response of arterial wall. In this study, their orientation in human common carotid artery was investigated using polarized light microscopy and an automated algorithm giving more than 4·106 fiber angles per slice. In total 113 slices acquired from 18 arteries taken from 14 cadavers were used for fiber orientation in the circumferential-axial plane. All histograms were approximated with unimodal von Mises distribution to evaluate dominant direction of fibers and their concentration parameter. 10 specimens were analyzed also in circumferential-radial and axial-radial planes (2-4 slices per specimen in each plane); the portion of radially oriented fibers was found insignificant. In the circumferential-axial plane, most specimens showed a pronounced unimodal distribution with angle to circumferential direction μ = 0.7° ± 9.4° and concentration parameter b = 3.4 ± 1.9. Suitability of the unimodal fit was confirmed by high values of coefficient of determination (mean R2 = 0.97, median R2 = 0.99). Differences between media and adventitia layers were not found statistically significant. The results are directly applicable as structural parameters in the GOH constitutive model of arterial wall if the postulated two fiber families are unified into one with circumferential orientation.

• Klíčová slova
• Arterial wall, Carotid artery, Collagen fiber direction, Histogram, Polarized light microscopy,
• MeSH
• adventicie MeSH
• algoritmy MeSH
• arteriae carotides * fyziologie   MeSH
• biomechanika MeSH
• extracelulární matrix * MeSH
• kolagen chemie   MeSH
• lidé MeSH
• mechanický stres MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kolagen MeSH

Most frequently used structure-based constitutive models of arterial wall apply assumptions on two symmetric helical (and dispersed) fibre families which, however, are not well supported with histological findings where two collagen fibre families are seldom found. Moreover, bimodal distributions of fibre directions may originate also from their waviness combined with ignoring differences between local and global fibre orientations. In contrast, if the model parameters are identified without histological information on collagen fibre directions, the resulting mean angles of both fibre families are close to ±45°, which contradicts nearly all histologic findings. The presented study exploited automated polarized light microscopy for detection of collagen fibre directions in porcine aorta under different biaxial extensions and approximated the resulting histograms with unimodal and bimodal von Mises distributions. Their comparison showed dominantly circumferential orientation of collagen fibres. Their concentration parameter for unimodal distributions increased with circumferential load, no matter if acting uniaxially or equibiaxially. For bimodal distributions, the angle between both dominant fibre directions (chosen as measure of fibre alignment) decreased similarly for both uniaxial and equibiaxial loads. These results indicate the existence of a single family of wavy circumferential collagen fibres in all layers of the aortic wall. Bimodal distributions of fibre directions presented sometimes in literature may come rather from waviness of circumferentially arranged fibres than from two symmetric families of helical fibres. To obtain a final evidence, the fibre orientation should be analysed together with their waviness.

• Klíčová slova
• Arterial wall, Collagen, Concentration parameter, Fibre direction, Fibre waviness,
• MeSH
• aorta MeSH
• arterie * MeSH
• biomechanika MeSH
• extracelulární matrix MeSH
• kolagen * MeSH
• mechanický stres MeSH
• prasata MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kolagen * MeSH

The study compares stresses and strains in the aortic wall derived using different constitutive models for various stress-strain conditions. Structure-based constitutive models with two fibre families with (GOH) and without (HGO) dispersion of collagen fibres are compared. The constitutive models were fitted to data from equibiaxial tension tests of two separated layers of the porcine aortic wall. The initial fit was evaluated with unrestricted parameters and subsequently, the mean angles of the fibre families and the angular dispersion were fixed to the values obtained from histology. Surprisingly, none of the tested models was capable to provide a good quality fit with histologically obtained structural parameters. Fitting the HGO model to experimental data resulted in two fibre families under angles close to ±45°, while the GOH model resulted in a nearly isotropic fibre distribution. These results indicate that both of these models suffer from the absence of isotropic strain stiffening. After having modified both models with corresponding additional members based on the Yeoh model of matrix, we obtained a perfect fit to the measured data while keeping the structural histology-based parameters. Finally, significant differences in compliance and resulting stresses and strains between different models are shown by means of simulations of uniaxial tension test, equibiaxial tension tests and inflation of the aorta.

• Klíčová slova
• Collagen, Constitutive modelling, Fibre direction, Histogram, Polarized light microscopy, Soft tissue,
• MeSH
• aorta * MeSH
• biologické modely * MeSH
• biomechanika MeSH
• mechanický stres MeSH
• prasata MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

A novel method for semiautomated assessment of directions of collagen fibers in soft tissues using histological image analysis is presented. It is based on multiple rotated images obtained via polarized light microscopy without any additional components, i.e., with just two polarizers being either perpendicular or nonperpendicular (rotated). This arrangement breaks the limitation of 90° periodicity of polarized light intensity and evaluates the in-plane fiber orientation over the whole 180° range accurately and quickly. After having verified the method, we used histological specimens of porcine Achilles tendon and aorta to validate the proposed algorithm and to lower the number of rotated images needed for evaluation. Our algorithm is capable to analyze 5·105 pixels in one micrograph in a few seconds and is thus a powerful and cheap tool promising a broad application in detection of collagen fiber distribution in soft tissues.

• MeSH
• Achillova šlacha metabolismus   MeSH
• algoritmy MeSH
• extracelulární matrix metabolismus   MeSH
• kolagen metabolismus   MeSH
• mikroskopie metody   MeSH
• optické zobrazování metody   MeSH
• počítačové zpracování obrazu metody   MeSH
• polarizační mikroskopie metody   MeSH
• prasata MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kolagen MeSH

The paper deals with the impact of chosen geometric and material factors on maximal stresses in carotid atherosclerotic plaque calculated using patient-specific finite element models. These stresses are believed to be decisive for the plaque vulnerability but all applied models suffer from inaccuracy of input data, especially when obtained in vivo only. One hundred computational models based on ex vivo MRI are used to investigate the impact of wall thickness, MRI slice thickness, lipid core and fibrous tissue stiffness, and media anisotropy on the calculated peak plaque and peak cap stresses. The investigated factors are taken as continuous in the range based on published experimental results, only the impact of anisotropy is evaluated by comparison with a corresponding isotropic model. Design of Experiment concept is applied to assess the statistical significance of these investigated factors representing uncertainties in the input data of the model. The results show that consideration of realistic properties of arterial wall in the model is decisive for the stress evaluation; assignment of properties of fibrous tissue even to media and adventitia layers as done in some studies may induce up to eightfold overestimation of peak stress. The impact of MRI slice thickness may play a key role when local thin fibrous cap is present. Anisotropy of media layer is insignificant, and the stiffness of fibrous tissue and lipid core may become significant in some combinations.

• MeSH
• analýza metodou konečných prvků MeSH
• arteriae carotides diagnostické zobrazování   patologie   MeSH
• aterosklerotický plát diagnostické zobrazování   patologie   MeSH
• biomechanika MeSH
• lidé MeSH
• magnetická rezonanční tomografie MeSH
• mechanické jevy * MeSH
• modely kardiovaskulární MeSH
• počítačové modelování podle konkrétního pacienta * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH