• Journal of Chest Surgery
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• v.28 no.6
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• pp.557-564
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• 1995

Microvel knitted double velour vascular grafts coated with biodegradable algin were evaluated in the canine experimental model as a new biologically coated Dacron graft. Three series of implantations were conducted involving the insertion of 6 mm diameter grafts in the abdominal aortae of mongrel dogs. The first series used the regular Microvel vascular grafts coated with algin,whereas the second and third series used Hemashield [collagen-coated grafts and the regular Microvel grafts with preclotting,respectively as control groups. Each series involved the implantation of one prosthesis for each of 2 preselected periods,namely 3 months and 6 months. In addition,algin-impregnated grafts were implanted for 4 hours,72 hours,2 weeks,and 4 weeks. All grafts were patent when the animals were sacrificed at intervals ranging from 4 hours to 6 months. Histological examinations revealed no obvious or significant differences in the healing characteristics of the algin-coated grafts and the control grafts after 3 months and 6 months of implantation. Endothelial cell-like cells were present on the midsegments of all grafts explanted from animals sacrificed after 3 months and 6 months,except a suspicious finding in the 3 month-implantation animal of a preclotted graft. With special stains,the algin became invisible between the polyester filaments during the first 3 months of implantation. This study has demonstrated that the use of a biodegradable algin coating is a feasible approach as biological sealants for textile arterial prostheses.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.281-285
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• 2010

Hemodialysis vascular access dysfunction (HVAD) due to the aggressive development of venous neointimal hyperplasia remains a major complication for patients with synthetic arteriovenous grafts. Paclitaxel-coated expanded polytetrafluoroethylene (ePTFE) grafts effectively prevent neointimal hyperplasia and stenosis. However, perigraft inflammation or edema can be another complication of ePTFE grafts, preventing early cannulation. Three different types of ePTFE grafts, including grafts without paclitaxel coating (control group, n = 12), grafts with paclitaxel coating at a dose density of $0.61ug/mm^2$ (low concentration group, n = 12), and grafts with paclitaxel coating at a dose density of $1.15ug/mm^2$ (high concentration group, n = 12) were placed in the backs of 12 rabbits, simultaneously. Six rabbits were euthanized after one week and the remaining six were euthanized two weeks after implantation. Perigraft inflammation, graft wall inflammation, stromal cell proliferation, blood vessel formation, tissue necrosis and edema were analyzed for the grafts in each animal. Inflammation surrounding the paclitaxel-coated grafts was significantly reduced compared to the control group. Stromal cell layers were detected at the interface between the graft and the surrounding tissue in the control group, infiltrated into the graft interstices, and differentiated into myofibroblasts for graft healing. Paclitaxel-coated grafts inhibited stromal cell proliferation and infiltration into the graft wall. Tissue necrosis and edema were not detected in either of the paclitaxel-coated graft groups.

• Archives of Reconstructive Microsurgery
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• v.5 no.1
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• pp.46-55
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• 1996

The purpose of this study is to investigate if there is a higher rate of free flap failure in cases of vein grafts compared to non-vein graft, and to analyze the clinical usefulness and necessity in elective free flap surgery. We have used 24 vein grafts in 208 free flaps from May, 1986 until August, 1995. Vein grafts were from 2cm to 50cm in length between the recipient and donor vessels. Reconstructed sites were 10 lower extremities, 8 head and neck, 4 hand, and 2 trunk. Vein grafts were used 14 for arterial, 6 venous, 4 in both arterial and venous anastomoses. We intentionally used long vein grafts longer than 5cm for improved blood flow in cases of peripheral vascular disease, radionecrotic wounds, lower leg trauma. Short vein grafts of about 3cm in length were used to overcome the shortage of vascular length in cases of unexpected vessel anomaly, short donor vessel, and difficult access to recipient vessels after radical neck dissection. All veins were carefully handled with ligation of very small branches and were transferred to the recipient site without irrigation. 8 flaps were failed out of a total of 208 free flaps, however there was no failure among the 24 cases that needed vein grafts between the donor and recipient vessels. Success rates between non-vein grafts free flaps and vein graft free flaps were 95.6%(8/184) and 100%(0/24). Even though the vein grafts increase the operation time and the number of anastomoses, they do not result in any increased failure rate of free flap surgery(4.4% versus 0%). In addition to the reducing tension between recipient and donor vessels, the surgeon can select better recipient vessels with excellent blood flow so that vein grfats in microsurgery can provide a high success rate of free flaps.

• Fibers and Polymers
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• v.6 no.1
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• pp.49-54
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• 2005

The purpose of this study has been to investigate the effect of dilation on the some mechanical properties of several types of warp-knitted vascular grafts. The structures of warp knit vascular grafts used in the experiments were reverse locknit, locknit, and Tricot. Various mechanical properties of these grafts were determined using devices developed for the purpose. Clinical data obtained were compared with experimental results of warp knit vascular grafts. The most important mechanical properties are found to be creep extension, bursting strengths, and compliance. Preliminary results indicate that vascular grafts are non-compliant and exhibit creep which is predictive of the long term dilation that has been noted in the clinical results. It is found that there is a positive correlation between experimental data and clinical results for at least the grafts tested.

• Journal of Chest Surgery
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• v.37 no.7
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• pp.570-577
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• 2004

CT angiography is now available to evaluate the early graft patency after coronary bypass surgery. We investigated whether patency or occlusion of the bypass grafts can be visualized by CT angiography and what factors effect the visuality. Material and Method: Fifty patients underwent scanning with a 4-slice computed tomographic scanner (Somatom Volume ZoomTM; Siemens, Germany) before being discharged after coronary artery bypass grafting. To evaluate graft patency and relationship between the quality of graft image and the characteristics of the diseased coronary vessels, 50 internal thoracic artery grafts, 18 radial artery grafts, and 56 vein grafts were included in this study. Result: All vein grafts (24 grafts; 32 anastomoses) to left coronary artery system were well visualized, but 3 grafts (4.7%) of 30 vein grafts (35 anastomoses) to right coronary artery system were not visualized. The latter was also occluded in invasive coronary angiographic study. Thirty-nine (78%) internal thoracic artery grafts were well visualized, 8 (16%) faintly visualized, and 3 (6%) not visualized, but all the internal artery grafts were well patent in invasive coronary angiographic study. Conclusion: Unvisualized vein grafts in CT angiography means occlusion of the grafts, but unvisualized arterial grafts in CT angiography may not mean occlusion of the graft but result from competitive flow between the graft and coronary artery. To confirm patency of the unvisualized arterial grafts, invasive coronary angiography is needed.

• Archives of Plastic Surgery
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• v.49 no.4
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• pp.543-548
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• 2022

Microvascular reconstruction frequently requires anastomosis outside of the zone of injury for successful reconstruction. Multiple options exist for pedicle lengthening including vein grafts, arteriovenous loops, and arteriovenous bundle interposition grafts. The authors performed a systematic review of arteriovenous bundle interposition grafts to elucidate indications and outcomes of arteriovenous grafts in microvascular reconstruction. A systematic review of the literature was performed using targeted keywords. Data extraction was performed by two independent authors, and descriptive statistics were used to analyze pooled data. Forty-four patients underwent pedicle lengthening with an arteriovenous graft from the descending branch of the lateral circumflex femoral artery. Most common indications for flap reconstruction were malignancy (n = 12), trauma (n = 7), and diabetic ulceration (n = 4). The most commonly used free flap was the anterolateral thigh flap (n = 18). There were five complications, with one resulting in flap loss. Arteriovenous bundle interposition grafts are a viable option for pedicle lengthening when free flap distant anastomosis is required. The descending branch of the lateral circumflex femoral artery may be used for a variety of defects and can be used in conjunction with fasciocutaneous, osteocutaneous, muscle, and chimeric free flaps.

• Journal of Chest Surgery
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• v.54 no.2
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• pp.81-87
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• 2021

Background: Artificial grafts such as polyethylene terephthalate (Dacron) and expanded polytetrafluoroethylene (ePTFE) are used for various cardiovascular surgical procedures. The compliance properties of prosthetic grafts could affect hemodynamic energy, which can be measured using the energy-equivalent pressure (EEP) and surplus hemodynamic energy (SHE). We investigated changes in the hemodynamic energy of prosthetic grafts. Methods: In a simulation test, the changes in EEP for these grafts were estimated using COMSOL MULTIPHYSICS. The Young modulus, Poisson ratio, and density were used to analyze the grafts' material properties, and pre- and post-graft EEP values were obtained by computing the product of the pressure and velocity. In an in vivo study, Dacron and ePTFE grafts were anastomosed in an end-to-side fashion on the descending thoracic aorta of swine. The pulsatile pump flow was fixed at 2 L/min. Real-time flow and pressure were measured at the distal part of each graft, while clamping the other graft and the descending thoracic aorta. EEP and SHE were calculated and compared. Results: In the simulation test, the mean arterial pressure decreased by 39% for all simulations. EEP decreased by 42% for both grafts, and by around 55% for the native blood vessels after grafting. The in vivo test showed no significant difference between both grafts in terms of EEP and SHE. Conclusion: The post-graft hemodynamic energy was not different between the Dacron and ePTFE grafts. Artificial grafts are less compliant than native blood vessels; however, they can deliver pulsatile blood flow and hemodynamic energy without any significant energy loss.

• Archives of Plastic Surgery
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• v.36 no.4
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• pp.380-384
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• 2009

Purpose: Autologous vessels remain the gold standard for vascular grafts in microanastomoses. However, they are sometimes unavailable and have a limited long - term patency. Synthetic vessels have high success rates in large - diameter reconstructions but failed when used as small - diameter grafts due to graft occlusion. It has been proved that endothelial cell seeding improves prosthesis performance and long - term patency. Among polyurethane, PET and ePTFE, polyurethane has the best affinity to endothelial cells and mechanical properties closest to human vessels. We examined the ability of endothelial cells to attach to a polyurethane graft manufactured by the electrospinning method. Methods: Endothelial cells, which were cultured from porcine internal jugular veins, were attached to polyurethane grafts with an internal diameter of 3 mm. The same cells were attached to allogeneic decellularized porcine internal carotid artery grafts as controls. Both of the 10 mm - long grafts were exposed to endothelial cells in a well for 1 hour. Each well contained $2{\times}10^5$ endothelial cells. The graft materials were rotated through 90 degrees every 15 minutes in order to minimize the effect of gravity. The extent of cell attachment was examined with the MTT assay. Results: The MTT assay showed good incorporation of endothelial cells into both grafts. For the evaluation of affinity, the number of attached cells was counted at 10 fields of microscopic examination with ${\times}40$ magnification. Endothelial cells adhered more to polyurethane grafts (mean, $127.4{\pm}6.2cells$) compared to porcine artery grafts (mean $45.8{\pm}5.1cells$)(p<0.05,Mann - Whitney test). Conclusion: In this study, we attached porcine endothelial cells to polyurethane grafts, manufactured by electrospinning. The grafts exhibited a better affinity to endothelial cells than allogeneic decellularized porcine internal carotid artery grafts. It is suggested that the time required for endothelial cells to attach to decellulized artery grafts may be longer than that which is required for attachment to polyurethane grafts.

• Journal of Chest Surgery
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• v.25 no.1
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• pp.42-48
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• 1992

Clinical improvement after coronary artery bypass surgery depends on the complete revascularization and patency of graft vessels. Patency rate and the factors influencing the patency were studied by examining 134 grafts in 55 patients at a mean follow-up of 22.8$\pm$4.2 months, range 15 days and 108 months. Serial studies were performed on 7 patients with 18 grafts. The over-all patency rate was 80.6%, and the rate more than 5 years after surgery was 50.0% with mean interval of 81 months. Patency rate of patients who had taken both aspirin and dipyridamole was higher than of patients who had been treated with aspirin only[80.5% vs 56.5%]. The average serum triglyceride level of patients who had graft stenosis or occlusion in at least one site was significantly higher than that of patients in whom all grafts were patent[262.1mg% vs 174.8mg%]. Patency rate of grafts in patient who had angina was 73.2% and in patients without angina 79.2%. 6 patients underwent successful percutaneous transluminal angioplasty for narrowed or occluded grafts.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1663-1667
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• 2013

Neointimal hyperplasia causes vascular access dysfunction in hemodialysis patients with synthetic arteriovenous (AV) grafts. Several studies have reported that paclitaxel- or sirolimus-eluting AV grafts inhibit neointimal hyperplasia and display lower rates of stenosis compared with control grafts. However, there have been few comparative studies of the efficacy of paclitaxel- and sirolimus-eluting grafts. We compared the neointimal hyperplasia of paclitaxel- and sirolimus-eluting grafts. AV grafts were implanted laterally between the common carotid artery and the external jugular vein in 12 female Landrace pigs. The animals were sacrificed six weeks after surgery. The neointimal hyperplasia at the anastomosis sites of the grafts was quantified using the ratio of the intragraft hyperplasia to the graft area (H/G ratio) at the graft-vessel interface. The area of intimal hyperplasia at the venous (paclitaxel 1.06 [0.72-1.56] vs sirolimus 2.40 [1.72-3.0] $mm^2$, P = 0.04) and arterial anastomosis sites (paclitaxel 0.93 [0.57-1.48] vs sirolimus 2.40 [1.72-3.0] $mm^2$, P = 0.04) was significantly different between the two groups. However, the H/G ratios for the venous anastomosis site (paclitaxel 0.25 (0.17-0.38) vs sirolimus 0.38 (0.2-0.66), P = 0.4) and the arterial anastomosis site (paclitaxel 0.19 (0.08-0.39) vs sirolimus 0.41 (0.34-0.50), P = 0.1) did not differ significantly between the groups. In conclusion, there was no significant difference in the inhibition of neointimal hyperplasia by sirolimus- and paclitaxel-eluting AV grafts.