Comparison of Oversized Artery and Vein Grafts for Interpositional Pedicle Lengthening in Rat Femoral Artery (original) (raw)
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International Journal of Morphology, 2017
When a vein segment is grafted into arterial circulation, biomechanical forces stimulate modification of its structure. This morphological adaptive response is progressive during a medium or long term and occludes the vessel lumen, leading to a graft failure. The objective of this study was to characterize the early morphological response of the vascular wall in a terminal-terminal vascular vein graft model in Wistar rats. A segment of the femoral vein was placed in the femoral circulation. An end to end microsurgical graft anastomosis technique was implemented and standardized in twenty rats. The samples were processed with histological technique to analyze the overall structure with hematoxylin and eosin, the composition of the vessel wall with Masson trichrome technique, the proliferating and smooth muscle cells were detected with immunohistochemistry (anti-PCNA, anti-actin and anti CD68) and the induction of apoptosis with TUNEL technique. The times periods studied were 1, 3 and 5 days postoperative. There is progressive increase of cell proliferation and intensity of the density detected by PCNA with its peak at postoperative day 3. Apoptosis was not evident in any of the postoperative days. Smooth muscle had no significant change in any of the time periods studied. Macrophage and leukocyte migration was evident since the first postoperative day with infiltration into the media by the 5th day. This study characterizes the morphological aspects in the early arterialization of the vascular wall in a vein graft process. These results contribute to a better understanding of the morphopathological mechanism involved in vein graft failure.
Vein grafts for arterial repair: an experimental study of the histological development of the intima
PubMed, 1983
Vein grafts were studied in rats using the incompatible DA and Lewis inbred strains. Allografts were performed in the Lewis-to-DA and DA-to-Lewis combinations with Lewis-to-Lewis isografts serving as controls. A 5 mm segment of iliolumbar vein was placed into a defect in the iliac artery, using micro-surgical techniques. Histological studies of the grafts at 1 hour, 1, 2, 4, 10 and 18 weeks after insertion showed that there was no evidence of rejection in any of the allografts and the tissue changes which occurred were indistinguishable from those of isografts. At the time of grafting, the vein wall consisted of a thin layer of collagen (50 microns thick) with a fine elastic lamina and no endothelium. By 1 week, most of this tissue was necrotic. By 2 weeks an endothelial layer was present and the wall was made of connective tissue, which increased in density by 4 weeks. At 10 weeks, a thick new intima had formed which doubled in thickness by 18 weeks. Electron micrographs revealed that this 'regenerated' intima was composed of smooth muscle cells surrounded by dense collagen and elastin. Sclerotic plaques were evident in some 18 week grafts.
Arterial grafts: clinical classification and pharmacological management
Annals of cardiothoracic surgery, 2013
In comparison with standard saphenous vein grafts, use of the internal mammary artery (IMA) as a coronary artery bypass graft has achieved superior long-term results. This is related to the differences in the biological characteristics between the venous and arterial grafts. However, even arterial grafts are not uniform in their biological characteristics. The variation in the perioperative behavior of the grafts and in their long-term patency may be related to different characteristics. These factors should be taken into account in the use of arterial grafts, some of which are subjected to more active pharmacological intervention during and after the operation to obtain satisfactory results. To better understand the biological behavior of the grafts, their common features and their differences, a clinical classification may be useful for a practicing surgeon. Based on experimental studies of their vasoreactivity combined with anatomical, physiological and embryological consideratio...
Microsurgery, 1992
Reported patency rates after standard end-to-end anastomoses for microvascular prosthetic grafts have been inconsistent and usually disappointing. A modified anastomotic technique is described in which the prosthetic graft is invaginated inside the arterial lumen. In this study of 6 cm lengths of 1 mm internal diameter polytetrafluoroethylene femoro-femoral bypass grafts in the rat, 6 (40%) of 15 grafts with standard anastomoses were patent at 6 months compared to 28 (90%) of 31 grafts using the modified anastomotic technique (P<O.OOl). With invagination of the prosthetic graft inside the arterial lumen, reliable high patency rates can be achieved with microvascular prostheses long enough for potential clinical applications. o 1992 Wiley-Ltss, inc.
The natural history of endothelial structure and function in arterialized vein grafts
Journal of Vascular Surgery, 1986
When the saphenous vein is used in the in situ position for arterial bypass surgery, it is associated with more optimal preservation of the endothelial lining and with improved graft patency compared with reversed vein grafts. However, it is not clear whether preservation of endothelial integrity persists after arterialization. The goal of this study was to establish whether preservation of the endothelium before arterialization is a critical factor in the development of late functional and morphologic abnormalities of autogenous vein grafts. Paired reversed and in situ vein grafts were created in 75 mongrel dogs. Veins to be used in the reversed position were excised and stored in either heparinized whole blood at 37 ° C or saline solution at 4 ° C. Veins were studied before and after arterialization. The veins were arterializcd by anastomosis to the carotid artery and excised at intervals of 1 day to 12 weeks for studies of the luminal production of prostacyclin and thromboxane A2 in addition to luminal morphology. Before arterialization, normothermic whole blood preserved biochemical function of the endothelium significantly better than hypothermic saline solution, but not as well as the in situ vein procedure. Soon after arterialization, all three vein grafts showed significant functional and morphologic abnormalities consistent with injury of the vein graft. Morphologic healing of the endothelial monolayer progressed slowly back to normal; however, the biochemical capacity of the vein graft never matched that of the prearterialized vein, nor that of normal host arteries. Regardless of surgical technique, all vein grafts exhibited a period of abnormal structure and fimction, which exposed them to the risk of thrombogenesis. This period of potential leukocyte or platelet interaction with the vein wall could lead to release phenomena as well as proliferative changes in the vessel wall. (J VAsc SURG 1986; 3:204-15.) Volume 3 Number 2 February 1986 Endothelial structure and function in vein grafts 205
Acute Intraoperative Arterial Elongation: an Experimental Study
European Journal of Vascular and Endovascular Surgery, 2001
small arterial defects resulting from either trauma or resection of an aneurysm often present difficult problems to the vascular surgeon. to demonstrate that certain arterial gaps as a result of traumatic injury or aneurysm resection could be closed with acute intraoperative arterial elongation. fifteen mongrel dogs underwent acute intraoperative arterial elongation of the right superficial femoral artery, with the left side used for a control vessel. arterial defects created surgically (median 50 (range 25 to 60 mm) mm). Appropriate length of artery was then undermined. A Foley catheter was placed proximally and distally directly beneath this undermined portion of vessel. The vessel is lengthened following 3 expansion/relaxation cycle of Foley catheter. Arterial gaps were closed by end to end anastomosis. Arterial pressure study was performed in all vessels. acutely, arterial pressure differences proximal and distal to the anastomosis were seen only when arterial gaps were exceeded 55 mm. There was no occlusion either acutely or after 4 weeks follow-up period. Light microscopic examination of arterial specimens revealed partial disruption of internal elastic lamina. At the end of the follow-up period, formation of neointima with regeneration of the internal elastic lamina was demonstrated. Scanning electron microscopy revealed minimal endothelial denudation. we believe that, acute intraoperative elongation can be used as an alternative technique to vein grafting for the repair of small traumatic arterial defects in selected cases.
Journal of Vascular Surgery, 2012
Background: Flow patterns and shear forces in native coronary arteries are more protective against neointimal hyperplasia than those in femoral arteries. Yet, the caliber mismatch with their target arteries makes coronary artery bypass grafts more likely to encounter intimal hyperplasia than their infrainguinal counterparts due to the resultant slow flow velocity and decreased wall stress. To allow a site-specific, flow-related comparison of remodeling behavior, saphenous vein bypass grafts were simultaneously implanted in femoral and coronary positions. Methods: Saphenous vein grafts were concomitantly implanted as coronary and femoral bypass grafts using a senescent nonhuman primate model. Duplex ultrasound-based blood flow velocity profiles and vein graft and target artery dimensions were correlated with dimensional and histomorphologic graft remodeling in large, senescent Chacma baboons (n ؍ 8; 28.1 ؎ 4.9 kg) during a 24-week period. Results: At implantation, the cross-sectional quotient (Q c) between target arteries and vein grafts was 0.62 ؎ 0.10 for femoral grafts vs 0.17 ؎ 0.06 for coronary grafts, resulting in a dimensional graft-to-artery mismatch 3.6 times higher (P < .0001) in coronary grafts. Together with different velocity profiles, these site-specific dimensional discrepancies resulted in a 57.9% ؎ 19.4% lower maximum flow velocity (P ؍ .0048), 48.1% ؎ 23.6% lower maximal cycling wall shear stress (P ؍ .012), and 62.2% ؎ 21.2% lower mean velocity (P ؍ .007) in coronary grafts. After 24 weeks, the luminal diameter of all coronary grafts had contracted by 63%, from an inner diameter of 4.49 ؎ 0.60 to 1.68 ؎ 0.63 mm (P < .0001; subintimal diameter: ؊41.5%; P ؍ .002), whereas 57% of the femoral interposition grafts had dilated by 31%, from 4.21 ؎ 0.25 to 5.53 ؎1.30 mm (P ؍ .020). Neointimal tissue was 2.3 times thicker in coronary than in femoral grafts (561 ؎ 73 vs 240 ؎ 149 m; P ؍ .001). Overall, the luminal area of coronary grafts was an average of 4.1 times smaller than that of femoral grafts. Conclusions: Although coronary and infrainguinal bypass surgery uses saphenous veins as conduits, they undergo significantly different remodeling processes in these two anatomic positions.
Vein grafts for arterial repair: their success and reasons for failure
PubMed, 1981
This article reviews briefly the history of the use of vein grafts for arterial repair. It concentrates upon the various reports of success and failure rates with this procedure, particularly in coronary artery and femoropopliteal bypass operations, and compares the two. Special emphasis is given to the two major intrinsic reasons for graft failure: intimal hyperplasia and atherosclerosis. Both of these are discussed with reference to the experimental evidence available to show the various factors that might be involved in the pathogenesis of these conditions.
Biomedical Papers, 2013
Objective. Abnormal haemodynamics is commonly agreed to be a major contributor to the development of distal anastomotic intimal hyperplasia. A new vascular graft design proposed by computational studies was used to demonstrate its surgical feasibility and to compare it with the conventional graft in a porcine model. Method. The device was used in 12 eight-month-old pigs, six received the new graft and six had a conventional graft. The proximal graft end was implanted into the aorta, the distal graft end was implanted into the iliac artery. The host artery was ligated in order to simulate occlusion. At 20 weeks after surgery the pigs were killed and the device was excised for histological and morphometric analysis. Results. In five experimental grafts the reconstruction was occluded due to thrombosis; only one prosthesis was patent showing a minimum of neointimal hyperplasia. In the control group too only three of the six grafts were patent. A histological analysis revealed, as the cause of occlusion, fibrous tissue overgrowth corresponding in structure to neointimal hyperplasia. Differences in the number of obliterations and in occlusion rates between the profiles of the two groups were evaluated using the median test (P<0.05). The results were not statistically significant. Conclusion. Although mathematical modelling had shown significant haemodynamic benefits of a naturally bifurcated graft, our study did not confirm its superiority over conventionally used prostheses.