MORPHOLOGICAL JUSTIFICATION OF THE SIGNIFICANCE OF LUMBAR ARTERIES IN THE PREVENTION OF SPINAL CORD ISCHEMIA IN ATHEROSCLEROTIC LESIONS OF ABDOMINAL AORTA.

OBJECTIVE: The aim: To investigate atherosclerosis of the abdominal part of the aorta and atherosclerosis of the lumbar arteries, aimed at improving surgical tactics during reconstructive interventions on the abdominal part of the aorta in patients with multifocal atherosclerosis. PATIENTS AND METHODS: Materials and methods: 20 autopsies were performed. The macro preparation consisted of the part of the abdominal aorta 1х1 sm taken along with a separated lumbar artery for 1-1,5 sm. Histological cuts were coloured with hematoxylin and eosin. The histochemical research was conducted in order to establish changes in all layers of blood vessels. The immunohistochemical research was carried out along with generally accepted histological methods in 10 cases to determine the morphological vessel wall functional state, connective tissue and smooth muscle components. RESULTS: Results: In all cases there were morphological signs of aortic atherosclerosis with different degrees of damage to the lumen. In none of the analyzed cases did we establish pathomorphological signs of atherosclerosis of the lumbar artery distal to the mouth. In the walls of the lumbar arteries, we noted the preservation of the layered structure, the integrity of the endothelial cells, the normal arrangement of smooth muscle cells. CONCLUSION: Conclusions: It was established that there cannot be the atherosclerotic occlusion of the lumbar artery, since there are no signs of atheromatous lesions in its walls, the structure of all layers is preserved, the endothelial damage is absent, the location and structure of the lining cells is normal.

Backscattered Scanning Electron Microscopy Approach for Assessment of Microvessels under Conditions of Normal Microanatomy and Pathological Neovascularization.

We evaluated the efficiency of an original method for studying of the microvascular bed under conditions of normal microanatomy and pathological neovascularization. The blood vessels, tissues surrounding the stent in the pulmonary artery and subcutaneously implanted titanium nickelide plate, atherosclerotic plaque, and vascular stent with restenosis were examined. The specimens were fixed in formalin and stained in OsO4, embedded into fresh epoxy resin, grinded, polished, and counterstained with uranyl acetate and lead citrate. Numerous vasa vasorum were found in all native vessels. Around the pulmonary artery stent and metal plates, numerous newly formed vessels of small diameter were seen. The intensity of neovascularization in atherosclerosis and carotid stent restenosis differed significantly. Our technique can be successfully used for evaluation of the microvascular bed.

An aortic model for the physiological assessment of endovascular stent-grafts.

BACKGROUND: The aim of this study was to manufacture a new aortic model with physiological properties, which could be used for long-term durability testing of endovascular stent-grafts, as per the recommendations of the Food and Drug Administration. METHODS: Porcine abdominal aortas were acquired to establish values for compliance. The aortic model was manufactured using a nanocomposite polymer. Latex mock aorta was used for comparison. A pulsatile flow phantom perfused the aortas and synthetic tubes at physiological pulse pressure and flow. Diametrical compliance and stiffness index were calculated over mean pressures from 30 to 120 mm Hg. Data were analyzed using one-way analysis of variance and Bonferroni's test. RESULTS: Flow circuit hemodynamic values were similar for porcine aorta and synthetic tubes. Compliance of aorta ranged from 2.97 ± 0.72 (mean ± SD) to 1.42 ± 0.37%/mm Hg × 10⁻². The polymer model showed significantly better compliance (range, 3.66 ± 1.05-2.72 ± 0.28%/mm Hg × 10⁻²; p < 0.05), with no significant difference in elastic stiffness index (range, 101.6 ± 28.9-51.3 ± 10.7 for aorta and 39.8 ± 8.5-34.2 ± 3.8 for polymer model; p > 0.05). It also showed anisotropic behavior similar to the aorta. Latex tubes showed compliance that was lower than that in aorta (range, 0.87 ± 0.24-0.86 ± 0.2%/mm Hg × 10⁻²) and failed by a significant distension on increase in pressure from mean of 90 mm Hg. CONCLUSIONS: We have developed physiologically relevant aortic model showing compatible anatomy, compliance, and viscoelasticity, which could be used for long-term fatigue analysis of vascular stents and grafts. The latex mock aortas can fail at physiological pressures.

Effect of diabetes on the healing process of synthetic grafts implanted in dogs: a preliminary study.

The deleterious effects of diabetes in peripheral vascular surgery and blood access are generally considered to be associated with the greater failure rate of vascular prostheses. To understand better these phenomena, we investigated the healing characteristics of an ePTFE graft in dogs. The animals were made diabetic after total pancreatectomy and the grafts implanted for scheduled periods of 24 h, 48 h, 1 wk and 1 month, either as thoracic (series I) or abdominal (series II) aortic substitutes. The same implantations were performed in non-diabetic dogs used as controls. The luminal surfaces of grafts implanted in diabetic dogs, either as thoracic or abdominal bypasses, proved to be more invaded by platelets as a result of the blood's increased platelet aggregation properties. The presence of endothelial-like cells spreading over the pannus after 1 month implantation was strikingly different in diabetic versus non-diabetic dogs. In the first group, the cells were fragile and less abundant, whereas in the second they were more adhesive, elongated and orientated in the direction of the blood flow.

Microporous, complaint, biodegradable vascular grafts for the regeneration of the arterial wall in rat abdominal aorta.

Microporous, complaint, biodegradable vascular grafts prepared from mixtures of polyurethane (PU) and poly-L-lactic acid (PLLA) can function as temporary scaffolds for the regeneration of the arterial wall in small-caliber arteries. This study was undertaken to determine the most suitable composition for PU/PLLA vascular grafts to ensure an optimal regeneration. Four types of PU/PLLA vascular grafts differing in percent weight of the PU/PLLA mixture, molecular weight of PLLA, and pore size were implanted into the abdominal aorta of rats (n = 32). Six weeks after implantation two implants of each graft type were evaluated by means of scanning electron microscopy and six implants were evaluated by means of light microscopy. In two types of the PU/PLLA vascular grafts, both of which were prepared from a 95%/5% weight PU/PLLA mixture with PLLA of molecular weight 500,000 but which had a different pore size, there was (I) absence of aneurysm formation and maintenance of arterial implant pulsations, (II) regeneration of a complete antithrombogenic neointima, (III) regeneration of a neomedia of comparable thickness to the media of normal rat abdominal aorta with the regeneration of elastic laminae almost throughout its thickness, and (IV) regeneration of a sufficiently supporting neoadventitia. These results demonstrate that a 95%/5% weight PU/PLLA mixture with PLLA of molecular weight 500,000 is the most suitable composition for PU/PLLA vascular grafts to ensure an optimal regeneration of a neoarterial wall that is of sufficient strength, compliance, and thromboresistance to function as a small-caliber arterial substitute. Pore size of these PU/PLLA grafts does not affect regeneration.

The course of blood vessels in the hip joint capsule of the dog.

The course and the arrangement of capsular blood vessels in the joint capsule's wall, together with their extracapsular origins, were investigated using cleared specimens that had been injected with Latex, or Technovit, or India-ink in serum. Arteries enter areas of the joint capsule's wall near its femoral as well as coxal attachment. The intramural vascular network is arranged in layers which are assigned to the stratum fibrosum and stratum synoviale, with one or two intermediate, less distinct layers in between. The ramification in the network of the stratum fibrosum is mainly stellate. Circular anastomoses connecting the supplied areas are located in the capsule's periphery. In the stratum synoviale, the vascular network is made of close, elongated meshes in a circular extension.

Flow patterns and preferred sites of atherosclerotic lesions in the human aorta - II. Abdominal aorta.

OBJECTIVE: As in Part I, to elucidate the role of fluid mechanical factors in the localized genesis and development of atherosclerotic lesions in man, here in the abdominal aorta. METHODS: Flow patterns and preferred sites of atherosclerotic lesions in the aorta were studied in detail using the same isolated transparent aortic trees prepared from humans postmortem and the flow visualization and cinemicrographic techniques as in Part I. RESULTS: Under steady flow simulating mid-systole, the flow was found to be disturbed at the aorto-celiac and aorto-superior mesenteric artery junctions by the formation of complex secondary and adverse flows along the lateral and posterior walls of the abdominal aorta. More complex secondary and adverse flows formed at the branching sites of the left and right renal arteries. Furthermore, considerable interactions occurred between the secondary and adverse flows formed at the branching sites of the above four arteries, resulting in the formation of a large and long recirculation zone along the lateral and posterior walls of the abdominal aorta corresponding to these branches. The velocity profile was almost flattened throughout the entire length of the descending aorta. CONCLUSIONS: Atherosclerotic lesions were found mainly at the posterior and lateral walls of the abdominal aorta where slow adverse and recirculation flows formed and where wall shear stress was low.

Anatomical study of the coexistence of the postaortic left brachiocephalic vein with the postaortic left renal vein with a review of the literature.

In a student course of gross anatomy dissection at Kanagawa Dental University in 2009, we found an extremely rare case of the coexistence of the postaortic left brachiocephalic vein with the postaortic left renal vein of a 73-year-old Japanese male cadaver. The left brachiocephalic vein passes behind the ascending aorta and connects with the right brachiocephalic vein, and the left renal vein passes behind the abdominal aorta. These two anomalous cases mentioned above have been reported respectively. There have been few reports discussing coexistence of the postaortic left brachiocephalic vein with the postaortic left renal vein. We discuss the anatomical and embryological aspect of this anomaly with reference in the literature.

The decellularized vascular allograft as an experimental platform for developing a biocompatible small-diameter graft conduit in a rat surgical model.

PURPOSE: The present study was aimed to assess the feasibility of using decellularized aortic allograft in a rat small animal surgical model for conducting small diameter vascular tissue engineering research. MATERIALS AND METHODS: Decellularized aortic allografts were infra-renally implanted in 12 Sprague-Dawley (SD) adult rats. The conduits were harvested at 2 (n = 6) and 8 weeks (n = 6), and assessed by hematoxylin and eosin (H&E), van Gieson, Masson Trichrome staining, and immunohistochemistry for von Willebrand factor, CD 31(+), and actin. RESULTS: Consistent, predictable, and reproducible results were produced by means of a standardized surgical procedure. All animals survived without major complications. Inflammatory immune reaction was minimal, and there was no evidence of aneurysmal degeneration or rupture of the decellularized vascular implants. However, the aortic wall appeared thinner and the elastic fibers in the medial layer showed decreased undulation compared to the normal aorta. There was also minimal cellular repopulation of the vascular media. The remodeling appeared progressive from 2 to 8 weeks with increased intimal thickening and accumulation of both collagen and cells staining for actin. Although the endothelial like cells appeared largely confluent at 8 weeks, they were not as concentrated in appearance as in the normal aorta. CONCLUSION: The results showed the present rat animal model using decellularized vascular allograft implants to be a potentially durable and effective experimental platform for conducting further research on small diameter vascular tissue engineering.

Os ramos colaterais da aorta abdominal em jaguatirica (Leopardus pardalis) / The collateral branches from abdominal aorta in ocelot (Leopardus pardalis)

A jaguatirica (Leopardus pardalis) é uma das espécies de felino silvestre que pouco foi investigada quanto a sua morfologia. Assim, o estudo objetivou detalhar a origem e distribuição dos ramos colaterais da aorta abdominal deste animal. [...] A aorta abdominal do L. pardalis teve origem entre T12 e L1, sendo a artéria celíaca o primeiro ramo visceral no sentido crânio-caudal, resultando nas artérias hepática, gástrica esquerda e esplênica. A artéria mesentérica cranial surgiu como segundo ramo da aorta abdominal, originando as artérias jejunais. Na sequência localizamos artéria pancreáticoduodenal caudal, artérias ileais, artérias ileocólicas, artérias renais direita e esquerda, artérias adrenais direita e esquerda e artérias ováricas ou testiculares direita e esquerda. Parietalmente, a aorta abdominal originou em média seis ramos lombares, bem como a artéria frenicoabdominal, as artérias circunflexas ilíacas profundas e artérias ilíacas externa e interna. A aorta abdominal gerou ainda a artéria mesentérica caudal, a qual dividiu-se em artérias cólica esquerda e retal cranial. A artéria cólica esquerda seguiu cranialmente paralela ao cólon descendente irrigando-o, originando em média 18 ramos, e anastomosando-se com a artéria cólica média. A artéria retal cranial seguiu em direção caudal distribuindo oito ramos à porção final do cólon descendente e ao reto, e uniu-se com a artéria retal média. Por fim, a aorta abdominal emitiu como ramo terminal a artéria sacral mediana. A vascularização arterial abdominal desta espécie é bastante semelhante ao descrito em felinos domésticos e demais mamíferos, com diferenças quanto ao número de artérias jejunais e origem das artérias renais.

The ocelot (Leopardus pardalis) is a species of wild cat that little has been investigated by their morphology. Thus, the study aimed to detail the origin and distribution of collateral branches from abdominal aorta this animal. [...]The abdominal aorta of L. pardalis originated between T12 and L1, and the celiac artery was first visceral branch in the craniocaudal direction, resulting in the hepatic a., gastric left a. and splenic a.. The caudal pancreaticoduodenal a., ileal aa., ileocolic aa., right and left renal aa., right and left adrenal aa., and. right and left ovarian aa. or testicular aa. were founded after. Parietally the abdominal aorta yielded an average of six lumbar branches, as well as frenicoabdominal aa., deep circumflex iliac aa. and external and internal iliac aa.. The abdominal aorta still originated the caudal mesenteric a., which is divided into the left colic a. and the cranial rectal a.. The left colic artery followed cranially parallel to the descending colon irrigating it, originating an average of 18 branches, and anastomosing with middle colic a.. The cranial rectal artery followed caudally emerging into eight branches uniting with the final portion of the descending colon and the rectum, together with the rectal middle a.. Finally, the abdominal aorta emerged as the terminal branch, the median sacral. The abdominal arterial vascularization of the ocelot is quite similar to that described in domestic cats, with differences in the number of jejunal arteries and origin of the renal arteries. The abdominal arterial vasculature of this species is quite similar to that described in domestic cats and other mammals, differing in number of the jejunal arteries and origin of the renal arteries.

Seeding of Dacron vascular prostheses with endothelium of aortic origin.

Seeding of autologous venous endothelium on Dacron vascular prostheses in dogs results in endothelial coverage of the prosthetic flow surface 4-6 weeks after implantation. Canine aortic endothelium, in contrast, usually fails to completely cover an unseeded prosthesis by pannus ingrowth even over much longer periods. To see if the success of endothelial seeding stems from a difference in the ability of venous and aortic endothelium to grow on prosthetic surfaces, we seeded freshly harvested autologous aortic endothelium on Dacron velour infrarenal aortic prostheses in dogs. Six weeks after surgery these prostheses showed the features reported to be typical of seeded prostheses. Scanning electron micrographs showed a luminal lining of flat polygonal cells without fibrin or adherent formed blood elements, and light microscopy showed an underlying layer containing aligned spindle-shaped cells with elongated nuclei and cell-lined subluminal channels. Control prostheses were covered with fibrin and platelet-rich thrombi everywhere except for limited pannus ingrowth at anastomotic sites. The results suggest that the success of autologous endothelial seeding cannot be ascribed to inherent differences in properties such as mitotic capacity or fibrinolysis between venous and aortic endothelium. The formation of complete endothelial linings by seeding must instead result from a more favorable condition for endothelial cell growth created by the cell harvesting or seeding process itself.

The impact of gelatin-resorcinol glue on aortic tissue: a histomorphologic evaluation.

PURPOSE: Although gelatin-resorcinol-formaldehyde glue has been used to treat acute aortic dissections for some time, concerns about formaldehyde's mutagenicity and carcinogenicity made it imperative to develop a new glue compound. Gelatin-dialdehyde glue was produced by omitting the formaldehyde component and replacing it with two less toxic aldehydes, glutaraldehyde and glyoxal. This study evaluated the histomorphologic effects of the new glue through in vivo use on the aortic tissue of domestic pigs. METHODS: Each animal's infrarenal aorta was glued around an implanted prosthesis. Histomorphologic evaluation was performed after operation after 1 and 4 weeks. RESULTS: The results demonstrated that the clinically observed tanning effect can be attributed primarily to the disintegration of the fiber texture, specifically collagenous, as well as smooth muscle fibers, and to the reciprocal alterations of the proteoglycan interstitial substance in the aortic wall. Macroscopic, microscopic, and electron microscopic analysis of the gluing process revealed an adequate healing process without any morphologically significant difference between formaldehyde and formaldehyde-free gelatin-resorcinol glue. CONCLUSIONS: Gelatin-dialdehyde glue is able to produce the same effects in the area of the aortic wall as the substantially more toxic gelatin-resorcinol-formaldehyde glue and thus could be recommended for clinical trials for treating acute aortic dissections thus far yielding excellent initial results.

Polyvinylidene fluoride (PVDF) as a biomaterial: from polymeric raw material to monofilament vascular suture.

This study identified the effects of various manufacturing processes on the crystalline microstructure, mechanical properties, and biocompatibility of a polyvinylidene fluoride (PVDF) suture. To achieve this, changes in the crystalline microstructure and the tensile behavior of PVDF monofilaments were monitored in vitro after different thermal processing, coloration, and sterilization treatments. In addition, the in vivo biocompatibility of the manufactured and sterilized PVDF suture was assessed by using it to anastomose a preclotted polyester vascular prosthesis as a thoracoabdominal bypass in a series of dogs. The tissue response was followed by histologic and scanning electron microscopy over implantation periods ranging from 4 h to 6 months. Differential scanning calorimetry and infrared spectroscopy (FTIR-ATR) showed that thermal processing and the addition of a coloring agent had a direct effect on modifying the crystalline microstructure and hence changing the mechanical properties. For example, thermal processing converted some of the alpha phase into the beta and gamma polymorphs, whereas coloration led only to a major increase in the beta-to-alpha ratio. The tensile properties were found to be optimized when the relative proportion of the beta and gamma phases combined compared to the alpha form gave rise to an FTIR A509/A532 absorption ratio between 4.0 and 4.5. Sterilization was found to cause some modifications to the crystalline microstructure near the surface of the monofilaments, but it did not change their mechanical properties. Pathologic examination of the anastomotic regions after different periods of implantation revealed a minimal cellular response, with no mineralization, intimal hyperplasia, or excessive fibrous tissue reaction. This good biocompatibility, together with other desirable characteristics such as ease of manipulation and satisfactory mechanical strength, makes PVDF an attractive alternative monofilament suture material for cardiovascular surgery.

Poly(glycolic acid) sutures in canine vascular anastomoses.

Poly(glycolic acid) (Dexon; Davis and Geck Company) canine vascular anastomoses between aorta and synthetic grafts and between severed femoral vessels were compared with comparable anastomoses made with Teflon-coated Dacron (Tevdek; The Deknatel Company) with respect to clinical performance, morphologic characteristics, and tensile strength. While the Dexon anastomoses performed well and were morphologically superior to Tevdek, their tensile strength was significantly lower. Implications of these findings for vascular wound healing are discussed.

Catheter visualization with resonant markers at MR imaging-guided deployment of endovascular stents in swine.

PURPOSE: To evaluate resonant circuits as markers for magnetic resonance (MR) imaging-guided placement of nitinol stents. MATERIALS AND METHODS: The study was approved by the institutional animal research committee and complied with National Institutes of Health guidelines for care and use of laboratory animals. Resonant circuits similar to catheter markers used at conventional angiography were placed proximally and distally to a nitinol stent in a stent delivery system. Resonant circuits were tested in vitro and in vivo for signal intensity levels that would enable visualization during MR imaging-guided stent deployment. Experiments were conducted by using real-time imaging with a 1.5-T unit. Stents (n = 9) were deployed in the vena cava (n = 2), abdominal aorta (n = 2), isthmus of the aorta (n = 2), and carotid (n = 2) and iliac (n = 1) arteries in five pigs. After intervention, the site of the stent was investigated with balanced fast field-echo MR imaging and contrast material-enhanced MR angiography. Blood flow velocities were measured in the stent lumen and next to the stent with velocity-encoded cine MR imaging. Level of agreement was determined with Bland-Altman analysis. RESULTS: During all interventions, resonant circuits provided highly visible MR signal that allowed fast and reliable visualization of the stent delivery system. Borders of loaded stents were clearly marked, which allowed precise stent placement in all experiments. Balanced fast field-echo MR imaging and contrast-enhanced MR angiography provided information about immediate postintervention position. Positions depicted on MR images were found accurate at postmortem examination. Results of Bland-Altman analysis showed good agreement between blood flow velocities measured in and next to the stent lumen, with a mean difference of -9 cm/sec +/- 5 (standard deviation). CONCLUSION: Resonant circuits are well suited for use at deployment of endovascular stents.

Angiographic imaging with 2D RF pulses.

Magnetic resonance angiography (MRA) was performed by using RF pulses designed to excite a limited spatial extent in two orthogonal directions. The restriction in the second spatial dimension can be used to increase inflow enhancement and to improve small field-of-view imaging. A rectangular excitation was produced with an "echo-planar" k-space trajectory and a sinc-modulated RF waveform. In vivo images have demonstrated that vessels are more clearly delineated with the two-dimensional excitation. Aliasing artifacts in small field-of-view imaging are significantly reduced, although in some cases complete elimination is not possible due to the nature of the gradient trajectory.