Gore-Tex Vascular Grafts Research Articles

Development of a testing machine for biaxial testing of soft tissue and biomaterials

Knowledge of the mechanical properties of soft tissues and biomaterials is the keystone for predictive modeling in cardio- and endovascular surgery, traumatology and orthopedics, neurosurgery, and the development of tissue-engineering constructs. Needed mechanical properties can be only explored via experimental tests. Therefore, mechanical experiments are forming the foundation of medical decision support systems, which are impossible without adequate mathematical models of the processes involved. Sirius University of Science and Technology has launched the project "Experimental research and mathematical modeling of the mechanical behavior of biomaterials". The goal of the project is to create an infrastructure for experimental study of the mechanics of soft tissues and biomaterials. At this stage, a machine for biaxial testing of soft tissues and biomaterials has been developed and put into trial operation. The developed machine takes into account the features of working with soft tissues: small sample size, maintaining certain environmental conditions to preserve the sample, various types of sample gripping to minimize edge effects and no slippage, non-contact methods for assessing displacement and deformation fields, variability in sample loading protocols. The result of the test is a data set that includes a test report and synchronized output readings of strain gauge, temperature, optoelectronic sensors with high-resolution images. Uniaxial verification tests of acrylic tapes VHB4910 were carried out by the developed machine. The results were compared with data obtained on a commercial dynamic mechanical analyzer RSA-G2 (TA Instruments) for similar materials under the same test conditions. A series of biaxial cyclic experiments were carried out for the pericardium of cattle, the cardiovascular patch Ecofolon PS04/PS01 (JSC NPK Ecoflon, St. Petersburg, Russia), and the GoreTex vascular graft (W.L. Gore and Associates, USA).

Results of long-term patency of small-diameter biodegradable vascular prostheses with atrombogenic drug coating of sheep model

Background. Preclinical tests of biodegradable small diameter vascular prostheses on a sheep model have been carried out.Aim. To assess the results of long-term patency and remodeling of biodegradable vascular prostheses based on polyhydroxybutyrate / valerate and polycaprolactone with an atrombogenic drug coating in a large laboratory animal model.Methods. We researched vascular prostheses made of polyhydroxybutyrate / valerate and polycaprolactone (PHBV/PCL) 4 mm in diameter with layer-by-layer vascular endothelial growth factor incorporated into the polymer framework, the main fibroblast growth factor, chemoattractant molecule containing SDF-1a (GFmix) surface, and additional modifying drug surface heparin and iloprost (PHBV/PCL/ GFmix/Heparin/Iloprost). Animals with implanted synthetic Gore-Tex vascular grafts with a diameter of 4 mm were included into a comparison group.Results. After one day of implantation it was revealed that the patency of biodegradable PHBV/PCL/GFmix/Heparin/Iloprost prostheses was 62.5%, while synthetic Gore-Tex prostheses were thrombosed in 100% of cases. At the same time, after 18 months of implantation, the patency of biodegradable vascular PHBV/PCL/ GFmix/Heparin/Iloprost prostheses decreased to 50%. Passable drug-eluting polymer grafts were completely resorbed after 18 months of implantation, and aneurysmically expanded newly formed vascular tissue was formed in their place.Conclusion. Vascular prostheses made of polyhydroxybutyrate/valerate and polycaprolactone showed better long-term patency results than synthetic prostheses used in the clinical practice. However, the strengthening of the external framework of the prostheses is required in order to prevent the formation of aneurysms.

Patency of Hemashield grafts versus ringed Gore-Tex grafts in middle hepatic vein reconstruction for living donor liver transplantation.

Backgrounds/AimsOwing to the short supply of homologous vein allografts, we previously used ringed Gore-Tex vascular grafts for middle hepatic vein (MHV) reconstruction in living donor liver transplantation. When ringed Gore-Tex grafts became unavailable, we used Hemashield vascular grafts. This study aimed to compare the patency and complication rates of Hemashield and ringed Gore-Tex grafts.MethodsThis retrospective two-arm study compared the study group that received Hemashield grafts (n=157) and the propensity score-matched control group that received ringed Gore-Tex grafts (n=157).ResultsIn the Hemashield and Gore-Tex groups, the recipient age was 54.7±9.4 and 53.3±6.3 years; Model for End-stage Liver Disease scores were 15.9±9.2 and 16.9±8.3; and graft-recipient weight ratios were 1.07±0.24 and 1.10±0.23, respectively. In the Hemashield group, V5 reconstruction was performed using single (n=113, 72.0%), double (n=39, 24.8%), and triple (n=3, 1.9%) anastomoses. The proportion of double and triple anastomoses for V5 and V8 was higher in the Hemashield group than in the Gore-Tex group. Two (1.3%) patients required MHV conduit stenting owing to early thrombosis of the Hemashield graft. There was no difference in conduit occlusion- free patient survival rates between groups (p=0.91). The incidence of accidental conduit migration in the Hemashield and Gore-Tex groups was 0 (0%) and 2 (1.3%), respectively.ConclusionsHemashield grafts used in MHV reconstruction demonstrated acceptably high short- and mid-term patency rates, no incidences of conduit migration, easy handling, and good flexibility for length adjustment. Therefore, we suggest that the Hemashield graft is the preferentially suitable prosthetic material for MHV reconstruction.

Identification of high-risk Fontan candidates by intraoperative pulmonary flow study

BackgroundPre-Fontan risk stratification is still less than optimal. We aimed to evaluate the effectiveness of intraoperative pulmonary flow study (IOFS), in combination with conventional preoperative evaluation, in the identification of high-risk candidates for the Fontan operation. MethodData from 37 patients (age: 38.1 ± 4.9 months) who underwent the Fontan operation with IOFS were retrospectively reviewed. After anastomosing the Gore-Tex vascular graft to the confluent pulmonary artery, IOFS was performed through the graft at various cardiac indices (CI) (1–4 L/min/m2) generated from a roller pump. Mean pulmonary artery pressure (mPAP) and left atrial pressure (LAP) were recorded. The patients were divided into two groups: those who required Fontan circuit fenestration (group Ff) and those who did not (group Fn). ResultsEleven patients (29.7%) required fenestration, intraoperatively (n = 4) and postoperatively (n = 7), due to hemodynamic instability. Heterotaxy syndrome (P = 0.005) and atrioventricular valvar regurgitation (P = 0.04) were more frequent, and ventricle posterior wall thickness (VPWT) was higher (P = 0.024) in group Ff. On IOFS, the increase in mPAP by CI was sharper in group Ff than in group Fn (P < 0.001) owing to an increase in LAP. On multivariable analysis, mPAP at a CI of 3.0 L/min/m2 from IOFS was the only predictor of fenestration and correlated with preoperative VPWT (R = 0.543, P = 0.001). ConclusionsIOFS may be helpful to identify high-risk Fontan candidates, and high mPAP at CI of 3.0 L/min/m2 on IOFS is a significant predictor of the requirement for fenestration. VPWT is an important preoperative risk factor which correlates with the IOFS results.

Reconstruction of the superior vena cava in patients with thymic malignancies.

e21116 Background: Thymoma is a kind of mediastinal tumors usually with an indolent growth pattern but malignant because of potential for local invasion, pleural dissemination, and even systemic metastases. Different from other malignant tumors, thymoma is often associated with autoimmune disorder s, the most common one being myasthenia gravis (MG). Complete surgical excision has been regarded as the standard of care for patients with thymoma, esp. locally advanced thymoma. The aim of this study was to investigate the effectiveness of reconstruction (Y-shaped bypass) of the superior vena cava (SVC) to treat locally advanced thymoma with SVC syndrome. Methods: We retrospectively studied data from 24 consecutive patients with locally advanced thymoma and SVC syndrome, operated on from October. 2015 to Dec. 2018 in Beijing Tongren Hospital. Their clinical data including clinical presentation, operation procedure, postoperative drug, adjuvant radiochemotherapy and follow-up were documented. 18 cases had MG, one having dermatomyositis, and two having interstitial pneumonia. Results: There were no perioperative deaths. All patients underwent complete resection and replacement with a GORE-TEX Vascular Graft (Y-shaped bypass) of SVC. The number of typeAB, B1, B2, B3 thymoma, and thymic carcinoma in this data were 2, 2, 7, 7, and 6, respectively. 7 patients had postoperative complications: 3 (with MG) experienced myasthenia crisis, 3 had pneumonia, and one had pulmonary embolisms, respectively. Both unfractionated heparin and Warfarin were routinely used the second or third day after surgery to maintain INR (International Normalized Ratio) between 1.8 and 2.5. All patients received mediastinal radiation therapy within one month after surgery. All patients were followed up for 2 months to 42 months. There were no patients dying and recurring. Conclusions: Reconstruction of SVC (Y-shaped bypass) is an effective way to treat locally advanced thymoma with SVC syndrome. After surgery, postoperative anti-thrombotic agents should be applied to prevent acute graft occlusion.

Complete superior vena cava resection for invasive thymoma

: Thymoma is the most common primary mediastinal tumour. It has the potential to invade mediastinal structures and requires complex surgical resection to gain clearance. We present the surgical technique for resection of a thymoma invading the superior vena cava (SVC). Our patient was a 58-year-old man with an anterior mediastinal mass. Computerized tomography (CT) scan showed a 55 mm mass invading the SVC. Histology from a CT-guided biopsy showed a B2 thymoma. Median sternotomy was performed and the thymoma was confirmed to be invading the SVC. The tumour extended superiorly to partially invade the left and right brachiocephalic veins. Additionally, it was infiltrating the right upper lobe, pericardium, and right phrenic nerve. We constructed a venous graft with a GORE-TEX vascular graft from the left brachiocephalic vein to the right atrium. This was followed by en bloc resection of the thymus and SVC with parts of the left and right brachiocephalic veins, along with a wedge resection of the right upper lobe, pericardium, and right phrenic nerve. The patient recovered well, and some initial facial oedema had resolved at his four-week follow-up appointment. Histology confirmed B2 thymoma with a clear resection margin.

Stenting and overdilating small Gore-Tex vascular grafts in complex congenital heart disease.

Gore-Tex® grafts are integral in the management of congenital heart disease. Issues of graft stenosis or somatic outgrowth may precipitate high-risk early surgery, and catheter intervention is a relatively under-reported management option. To assess efficacy, safety, and outcomes of stenting and overdilating small Gore-Tex® vascular grafts with the aim of optimizing surgical timing. Retrospective analysis of single-center, 13-year experience of 93 graft stenting interventions or reintervention in 80 patients, with the aim of relieving stenosis ± overdilation, to depose surgical graft revision or optimize surgical timing and candidacy. Median preintervention graft diameter was 52% (IQR 43-63) of nominal size, postintervention this increased to median 102% (IQR 96-120) [P < 0.001]. Overdilation was achieved in 54%; of these, the median final internal lumen was 126% (IQR 113-132) [P < 0.001]. Mean oxygen saturations increased from 69% to 82% [P < 0.001]. Adverse event rate was 14.9%; this includes mortality (3.2%) and atrioventricular conduction block (8.5%). Univariate analysis and logistic regression showed a significant relationship between adverse events and young age [P < 0.01], low weight [P < 0.01], univentricular physiology [P < 0.001], use of femoral venous access alone [P = 0.03], and intervention on a right ventricle to pulmonary artery conduit [P = 0.03]. Within respective indication groups, 74% were bridged to elective cavopulmonary shunt, 95% were bridged to biventricular surgery, and 78% of long-term palliative care patients continue under follow-up. Gore-Tex® vascular grafts can be stented effectively and expanded beyond nominal diameters by around +26%. This improves oxygen saturations, providing excellent palliation and optimized surgical timing. Adverse events are most frequent in precavopulmonary shunt patients. Gore-Tex® grafts are widely used in the palliation of cyanotic congenital heart disease. Grafts may become stenosed and do not allow for somatic growth. Over a 13 year period, graft stenting was performed in 80 patients (93 technically successful interventions, 4 unsuccessful.) Median internal lumen change was +50% (of nominal graft size), mean oxygen saturation change +13%. Over-dilation was performed in more than half of the cohort, with a median gain of +26% on nominal graft size. In precavopulmonary shunt patients, there was a moderate incidence of serious complications. Clinically useful deferral of surgery was achieved for the majority.

Congenital abdominal aortic aneurysm in a term neonate: a case report

Background: Congenital abdominal aortic aneurysm (AAA) is a rare condition in neonates. To our knowledge, the natural course of the disease in a Thai neonate has not yet been reported. Objectives: To report the characteristics and clinical course of congenital AAA in a Thai neonate. Methods: A female Thai infant was born spontaneously at term (3,990 g) having a large, pulsatile, abdominal mass. Computed tomographic angiography (CTA) of the abdominal aorta showed a large infrarenal AAA, and a fusiform aneurysm at the left common iliac artery. Two small right renal arterial aneurysms were also noted. The large aneurysm was partially resected and a Gore-Tex vascular graft was placed at 15 days old. Histopathology of the aneurysmal wall revealed no specific etiology. Ultrasonography revealed thrombosis of the graft on the 13th day after surgery. Results: Repeated CTA of the abdominal aorta at age 13 mo showed complete thrombosis of the graft with reconstitution of collateral circulation. The infrarenal AAA and left common iliac aneurysm and 2 small right renal artery aneurysms were completely thrombosed. The patient grew and developed normally to the most recent follow up at age 36 mo. Conclusions: Congenital AAA with failure of graft replacement may regress spontaneously. Keywords: Abdominal aortic aneurysm, neonate, aortic aneurysm, idiopathic abdominal aortic aneurysm, neonatal abdominal aortic aneurysm, pulsatile abdominal mass

GORE-TEX VASCULAR GRAFT FOR MACULAR BUCKLING IN HIGH MYOPIA EYES

To evaluate a new application of an expanded polytetrafluoroethylene (Gore-Tex) vascular graft for use in macular buckling surgery for treatment of highly myopic eyes. The Gore-Tex vascular graft was used as a macular buckling material in eight consecutive cases of myopic macular diseases which included fovea detachment, foveoschisis, or macular hole retinal detachment. Retinal reattachment was achieved in all cases except one which had partial resolution (88%). The postoperative best-corrected visual acuity ranged from 20/2000 to 20/100 depending on the degree preexisting macular degeneration, and significant better than the preoperative best-corrected visual acuity (P = 0.048, paired t-test). During the follow-up period, which ranged from 8 months to 3 years, no eye developed buckle-related complications such as infection or dislocation. The initial pilot results from this series using a Gore-Tex graft for macular buckling is promising. Throughout the follow-up period, the Gore-Tex was well tolerated in the highly myopic eyes. Large scale and long-term follow-up is warranted.

Sudden-Onset Paraplegia and Ischemia of the Lower Extremities from Acute Aortic Occlusion following Type A Acute Dissection

Herein, we report the case of a 51-year-old man who presented with sudden-onset paraplegia and ischemia of lower extremities, with low back pain. CT scanning revealed Type A acute dissection with occlusion of the infrarenal abdominal aorta and bilateral iliac arteries. A lumbar catheter was inserted for cerebrospinal fluid drainage and we repaired Type A aortic dissection with ascending aorta and total arch replacement combined with stent-graft elephant trunk technique by using innominate cannulation and an aorto-femoral bypass. On postoperative day three, ischaemic symptoms including paraplegia totally disappeared and he was discharged from the hospital on postoperative day 44. not restored. Finally, an aorto-femoral bypass was performed using an 8-mm Gore-Tex Vascular Graft (W.L. Gore & Associates, Inc., Flagstaff, AZ, USA) in an end-to-end fashion to 1 limb of the 4-branch prosthetic graft (Figure 2). However during the operation we did not find the thrombus formation in the femoral artery. The patient's left lower-extremity perfusion improved, and the distal pulses returned after the procedure. Post-operative treatment for spinal cord injuries and ischemia-reperfusion injuries included that increasing the blood pressure >140 mmHg, intravenous methylprednisolone 1 gram/day for 3 days, and maintaining the cerebrospinal fluid pressure <10 cm H 2 O. On postoperative day one, continuous hemodiafilteration was started because of acute renal failure (ARF) and reduced urinary output. On postoperative day three, ischaemic symptoms including paraplegia totally disappeared. The patient's renal function was rescued from dialysis 1 month later and he was discharged from the hospital on postoperative day 44. Postoperative 3-D reconstruction of the CT-scan revealed the vascular prosthesis of the ascending aorta, the 4-branch prosthetic graft, the stent graft in the descending aorta and the aortofemoral graft were all patent and no thromboemboli were identified (Figure 3).

Thrombogenicity of a New Injectable Biocompatible Elastomer for Aneurysm Exclusion, Compared to Expanded Polytetrafluoroethylene in a Human Ex Vivo Model

ObjectivesCustomized Aortic Repair (CAR) is a new concept for endovascular aortic aneurysm repair in which a non-polymerised elastomer is injected to fill the aneurysm sac around a balloon catheter. Amongst other variables, the thrombogenicity of the elastomer should be tested, before further clinical experiments can take place. The aim of this human ex vivo study was to measure the thrombogenicity of the elastomer and to compare it to expanded polytetrafluoroethylene (ePTFE). Design and materialsIn a validated ex vivo model, non-anticoagulated blood was drawn from the antecubital veins of 10 healthy donors with a 19-gauge needle. It was drawn through elastomer tubes and through ePTFE Gore-Tex vascular grafts, both 60 cm long and with an inner diameter of 3 mm. MethodsFibrinopeptide A (FPA) and P-selectin expression was measured in blood samples, collected at the end of the grafts. After the experiments, the deposition of platelets and fibrin onto the grafts was visualised by scanning electron microscopy. ResultsFor these graft types, a progressive increase in FPA production was observed in time. No significant difference was observed between the elastomer and ePTFE grafts (p > 0.05). No increase in P-selectin expression, and thereby no platelet activation, was observed in the perfusate of either grafts (p > 0.05). By scanning electron microscopy, numerous platelet aggregates were observed on the ePTFE grafts, whereas just a few adhered platelets and no aggregates were observed in the elastomer grafts. ConclusionsThe elastomer in its current formulation has a low thrombogenicity, comparable to ePTFE, making it an ideal substance for endovascular aneurysm sac filling. Further research should clarify the feasibility of CAR in vivo.

Comparing frozen saphenous vein with Gore‐tex in vascular access for chronic hemodialysis

Performing chronic hemodialysis in patients suffering from end-stage renal disease needs a suitable vascular access like arteriovenous fistula in the upper limbs and bridge fistula in the upper or lower limbs, and also use of permanent and temporary catheters. The purpose of this study is to compare frozen saphenous vein versus using synthetic Gore-tex vascular graft for A-V fistula. In the prospective randomized study, 70 patients needing for dialysis access were randomly divided into two groups. We performed the frozen saphenous vein A-V fistula in the test group and the Gore-tex fistula in the control group. An assessment included function criteria (fistula thrill and murmur) and complications (infection and thrombosis) in planned intervals. At the end of the follow-up period, the flow rates of all fistulas were assessed by Doppler sonography. The data were compared. Comparing the function criteria (fistula murmur and thrill) and the flow rate of the test group (frozen saphenous A-V fistula) and the control group (Gore-tex method) showed no significant difference and also no significant difference between two groups in thrombosis. Infection rate of the Gore-tex method was significantly high (p < 0.05). Arteriovenous fistula was an acceptable alternative in chronic hemodialysis, and frozen saphenous vein arteriovenous fistula was superior to Gore-tex arteriovenous graft in some aspects.

Novel visceral reconstruction for paravisceral aortic aneurysm complicated with aortoiliac occlusion

Visceral ischemia is a serious factor in the postoperative morbidity and mortality of suprarenal aortic reconstruction. We report a case of a patient who underwent surgical repair for a paravisceral aortic aneurysm complicated with aortoiliac occlusion, using a novel visceral reconstruction. Prior to proximal anastomosis of the aorta, we reconstructed visceral arteries by bypass grafting to the superior mesenteric artery and right renal artery (RA), using a straight 12-mm prosthetic graft originating from the intact descending aorta. During the visceral reconstruction, selective cold crystalloid perfusion of the RA was performed. We then underwent the proximal anastomosis of the aorta just below the celiac trunk using a Y-shaped prosthetic graft 18×10mm in diameter, in keeping the adequate visceral perfusion. Finally, a femoro-femoral bypass was performed with an 8-mm Gore-Tex Vascular Graft, and the left limb of the Y-shaped graft was sewn onto the side of this prosthetic graft. Postoperative computed tomography (CT) identified the successful repair of the aneurysm without any complications. Our novel visceral reconstruction could allow the surgeon to provide a physiological perfusion of visceral organs and prevent the potential visceral ischemia, during suprarenal aortic reconstruction.

Saphenous Vein Graft Aneurysm After Renal Transplantation: A Case Report

Saphenous Vein Graft Aneurysm After Renal Transplantation: A Case Report

Stent expansion of stretch Gore‐Tex grafts in children with congenital heart lesions

To evaluate the efficacy and safety of expanding vascular shunt grafts beyond original nominal diameter using stents. Bench testing confirmed the expandability of 3.5 mm and 4.0 mm vascular Gore-Tex stretch grafts. A retrospective analysis included eleven systemic to pulmonary artery shunts with diminished flow which were stented with the aim of increasing the original nominal diameter of the shunts. During bench testing, the grafts could be expanded to 4.5 mm and 5.8 mm, respectively. Fourteen stents were implanted in 11 stretch grafts a median of 18.9 months (3.2; 21.6 months) after shunt surgery. There was a median increase in diameter of 1.4 mm (0.9; 1.7 mm) [P = 0.001, 95% CI: 0.47; 1.7) from original nominal to final stented diameter of the shunts with a median gain of 28%. A simultaneous improvement in saturations from a median of 73% (66; 77%) to 87% (84; 89%) [P = 0.015; 95% CI: 3; 22] was observed. No complications were experienced during the procedures. In our limited experience, stretch Gore-Tex vascular grafts can be safely expanded beyond nominal diameters using high pressure vascular stents. This leads to improvement in saturation and pulmonary blood flow. It allows the clinician to tailor pulmonary flow in relation to pulmonary artery size and growth, ensuring best possible timing for the next surgical procedure.

Off-Label use of Stretchable Polytetrafluoroethylene: Overexpansion of Synthetic Shunts

To describe our experience with balloon dilatation and stenting of modified systemic-to-pulmonary artery (PA) shunts in relation to an assessment and interpretation of the mechanical properties of thin-walled expandable polytetrafluoroethylene (ePTFE) stretch vascular grafts. Our pediatric cardiology/cardiac surgery database was reviewed to identify all infants and children with a modified systemic-to-PA shunt who underwent cardiac catheterization. Reports and images were reviewed. Thin-walled stretchable and regular Gore-Tex vascular grafts were mechanically compared using tensiometry. 11 patients underwent dilatation or stenting procedures of a systemic-to-PA shunt. No major complications occurred and none of our patients died during or due to this intervention. High pressures in balloons and stents with diameters larger than the graft were used. Shunt diameters and oxygen saturation levels increased from 2.05 +/- 1.25 mm to 4.75 +/- 0.88 mm and with 12 +/- 6.8%, respectively. In 6 patients re-catheterizations were performed. Four patients died, all with patent shunts. The fail-stress and the fail-strain in the circumferential direction of the stretchable graft were significantly higher than in the non-stretchable graft. Dilatation and stenting of stenosed modified systemic-to-PA shunts is feasible and safe. Dilatation and stenting of these shunts to calibers larger than those provided by the manufacturer is possible. Results of our technical study posit a great advantage for the use of the thin-walled stretch configuration of ePTFE.

Comparing the saphenous vein with the Gore-tex bridge fistula in thigh for chronic hemodialysis

BACKGROUND: Performing chronic hemodialysis in patients suffering from end stage renal disease needs a suitable vascular access like A–V fistula in upper limbs, bridge fistula in upper or lower limbs, and use of permanent and temporary catheters. The purpose of this study is to compare the saphenous vein loop fistula as a venous autograft versus using the synthetic Gore-tex vascular graft for creating loop A–V fistula in thigh for hemodialysis. METHODS: In the context of a prospective randomized study, seventy patients needing bridge fistula for dialysis access were randomly divided into two groups. We performed the loop saphenous A-V fistula in the test group and the Gore-tex loop bridge fistula in the control group. An assessment was made of the function criteria (fistula thrill and murmur) and complications (infection and thrombosis) in planned intervals. At the end of a year of follow-up the flow rate of all fistulas were assessed by means of Doppler sonography. These data were compared with each other. RESULTS: Comparing the function criteria (fistula murmur and thrill) of the loop saphenous A–V fistula and the Gore-tex method showed no significant differences (p < 0.8). There was no significant difference between the two groups in thrombosis (p < 0.8). The infection rate of the Gore-tex method was significantly high (p < 0.05). However, the flow rates showed no significant differences (p < 0.8). CONCLUSIONS: Essentially we showed that arteriovenous fistula was an acceptable alternative for arteriovenous graft in the thigh for performing chronic hemodialysis and that saphenous vein loop arteriovenous fistula was superior to Gore-tex loop arteriovenous graft from some aspects.

Histopathologic study of minced and injected expanded polytetrafluoroethylene (Gore-Tex) in quadriceps muscle of rats for injection laryngoplasty

Objective Gore-Tex has not yet been used as an injection material, and no animal study has been performed. The purpose of this study was to investigate the histopathological and volumetric changes of minced and injected expanded polytetrafluoroethylene (Gore-Tex) in the quadriceps muscle of rats to find out its possibility as an injection material in future injection laryngoplasty. Design A prospective study was performed in 13 Wistar rats. Methods The 50 ± 5 mg Gore-Tex vascular graft was minced until it was fine enough to pass through a 16G injection cannula. To create viscosity in order to avoid precipitation, minced Gore-Tex was mixed with sodium hyaluronate (SH) gel. 0.5 ml of this mixture was injected into the middle part of the right quadriceps muscle of each subject. Then, pure SH (0.5 ml) was injected into the middle part of the left quadriceps muscle of each subject. To compare the volumetric and histopathological changes of the injection area occupied by the materials over the time, two rats were sacrificed 1 day after the procedure, four rats after 1 month, four rats after 3 months and three rats after 6 months. Results In pure SH: SH was observed as an effusion in the muscle of one subject on the first day only. We did not detect SH in the muscle in the first, third and sixth months and, as a result, there was no augmentation. Inflammation and fibrosis was not detected in any of these applications of SH. In minced Gore-Tex + SH gel mixture: SH was again eliminated from the muscle in a very short period of time, but the remaining Gore-Tex created a 15.8% volumetric gain. Fibrosis and capsule formation began in the first month and, in the sixth month; we observed connective tissue surrounding the Gore-Tex material. Ingrowth of connective tissue into the Gore-Tex, though not present in the first month, occurred partially in the third and significantly in the sixth month. In addition, we observed foreign body granuloma formation after the third month. Conclusions Pure SH, though easily applicable, was immediately eliminated leaving no trace. In the relatively difficult applications of Gore-Tex mixed with SH, however, there was residual Gore-Tex present in all subjects throughout the study. Gore-Tex may be an applicable material for injection laryngoplasty.

In Situ Tissue Engineering of the Bile Duct Using Polypropylene Mesh-Collagen Tubes

Multiple attempts have been made to replace biliary defects with a variety of materials. Recently, successful biliary reconstruction using the Gore-Tex vascular graft has been reported experimentally and clinically. We designed a new artificial bile duct consisting of collagen sponge and polypropylene mesh. We presently evaluated the feasibility of using this prosthesis as a scaffold for bile duct tissue regeneration in a canine model. Our prosthesis, a sponge made from porcine dermal collagen, is reinforced with a polypropylene mesh cylinder. We used the prosthesis to reconstruct the middle portion of the common bile duct in seven beagle dogs to evaluate its efficacy. While one dog died of biliary stricture 8 months after operation, six survived without problems to scheduled time points for tissue evaluation at 1 to 12 months. All prostheses had become completely incorporated into the host. A confluent epithelial lining was observed within 3 months. In cholangiograms the prosthesis displayed long-term patency in the six dogs and provided satisfactory bile drainage for up to 12 months. Our graft thus shows promise for repair of biliary defects and should lead to development of a new treatment for biliary reconstruction.

Artificial Esophagus With Peristaltic Movement

In this study, we have developed an artificial esophagus simulating peristaltic movement with the use of a nickel-titanium shape memory alloy (NiTi-SMA) actuator. Serial pairs of NiTi-SMAs were placed around a Gore-Tex vascular graft in a helical position such that they obliterated the lumen of the vessel when they contracted. In an animal experiment using a goat, the cervical esophagus was resected over a length of approximately 20 cm. The artificial esophagus was anastomosed with the remaining cervical esophagus. When a direct current of 500 mA at 5 V was applied to the NiTi-SMAs, the first pair of the NiTi-SMA contracted. The following pairs of the NiTi-SMAs contracted consecutively. The entire contraction of the artificial esophagus was similar to the esophageal peristaltic movement observed by x-ray examination in humans. The results showed the possibility that the artificial esophagus could function as an artificial esophagus having peristaltic movement.