Synthetic Polytetrafluoroethylene Research Articles

Outcomes of Aortoiliac Occlusive Disease Treated by Aorto-femoro-popliteal and Distal Bypass Surgeries: A Prospective Cohort Study

Introduction: Aortoiliac occlusive disease can contribute to lower extremity ischaemic symptoms requiring intervention. Though proximal aorto-femoral bypass surgery has been the mainstay of intervention, the delayed healing in many patients necessitates exploration of other techniques, including sequential revascularisation. Aim: To estimate the outcomes of aortoiliac occlusive disease treated by aorto-femoro-popliteal and distal bypass surgeries. Materials and Methods: A prospective cohort study was conducted to determine the treatment outcomes of 25 patients with aortoiliac occlusive disease visiting a tertiary care centre of Government Stanley Medical College and Hospital, Chennai, Tamil Nadu, India from October 2012 to December 2014. Data regarding the aetiology of the disease, co-morbidities including substance use, degree of disease involvement, and treatment modalities were collected. Data was analysed by Statistical Package for Social Sciences (SPSS) software version 22.0. The Chi-square test was used to compare outcomes with different treatment modalities, and a p-value <0.05 was considered statistically significant. Results: The mean age of the study participants was 58.3±2 years (range 40 to 70 years). The study noted that the most common aetiology for aortoiliac occlusive disease was atherosclerosis in 18 (72%) cases. The most common associated co-morbidity was smoking in 18 (72%) cases. Abnormal profunda patency was noted in 15 (60%) cases and synthetic Polytetrafluoroethylene (PTFE) was used in 80% of sequential bypass cases. A significantly higher proportion (86.7% vs 30%) of people treated by the sequential procedure achieved relief from claudication pain (p-value<0.05). The complication noted after the proximal bypass was pseudoaneurysm (20%), and the only complication noted after the sequential bypass was graft thrombosis (13.33%). The mean Ankle-brachial Index (ABI) score and ulcer healing time were also significantly higher in the sequential bypass procedure (p-value<0.05). Conclusion: Sequential bypass offers better advantages than proximal bypass for treating aortoiliac occlusive disease. It was found to be a safe and effective method for successful limb salvage, ensuring successful limb revascularisation and sufficient outflow to maintain graft patency.

A clinical case of surgical treatment of a child with aneurysms of the abdominal aorta and aortic bifurcation, superior mesenteric artery and multiple aneurysms of the main arteries

A brief literature review on abdominal aortic aneurysms in children and our own observation of surgical treatment of a 5-year-old child with an aneurysm of the abdominal aorta and aortic bifurcation, an aneurysm of the superior mesenteric artery, and multiple aneurysms of the arteries of the lower extremities has been presented in the paper. Staged replacement of the aortic aneurysm and superior mesenteric artery with synthetic polytetrafluoroethylene prostheses was performed. The features of surgical interventions, difficulties and complications that the authors encountered during the treatment of the child are described.

Synthetic polytetrafluoroethylene patches for irreparable rotator cuff tears-how are they doing at 5 years?

Treating massive and irreparable rotator cuff tears are problematic. Several studies have reported that polytetrafluoroethylene (PTFE) patches demonstrated excellent construct integrity and positive clinical and patient outcomes. However, these studies either had small sample sizes or short follow-up periods. To determine the survivorship, efficacy, and medium-term (2-19 years) outcomes of PTFE patch repairs. This retrospective study used prospectively collected data to establish the medium-term outcomes of PTFE interposition patch repairs for massive rotator cuff tears that could not be repaired by the standard technique. Patients included those who met the ≥2-year follow-up criteria post repair. Standardized assessments of patient-ranked shoulder pain and function and shoulder strength and passive range of motion (ROM) were performed preoperatively and at follow-up visits. Radiographs and ultrasonography were used to evaluate repair integrity, measure proximal humeral head migration, and determine glenohumeral arthritis scores. Forty-one shoulders formed the study cohort at a mean follow-up period of 5 years (range: 2-19 years). The mean age of this group was 72 (standard deviation: 10; range: 50-88) and had 14 cm2 tears at surgery. Twenty-five of 41 (61%) PTFE interposition patch repairs remained intact at an average of 5 years postrepair. Thirteen patches failed at the patch-tendon junction, 1 was removed, and 2 patients underwent reverse total shoulder replacement. Patient-ranked shoulder stiffness (P<.05), frequency of pain during activity and sleep (P<.001), pain levels during overhead activity and rest (P<.001), and overall shoulder function significantly improved from bad preoperatively to fair at the mean 5-year postoperative visit (P<.001). No significant improvements were demonstrated in dynamometer-measured shoulder strength maneuvers and passive ROM. All patients demonstrated proximal humeral head migration on shoulder radiographs regardless of repair integrity (mean Upper Migration Index=1.2). Failed repairs were associated with higher mean preoperative glenohumeral arthritis grades compared with intact repairs (grade 2 in failed repairs compared with grade 1 in intact repairs) (P<.01). PTFE interposition patch repairs for massive and irreparable tears had good construct integrity and clinical outcomes at 2 years. These outcomes were not maintained. PTFE patch repairs often failed at the patch-tendon junction at 4 years and beyond and were ineffective in (1) preventing proximal humeral head migration, (2) stopping progression of glenohumeral arthritis, and (3) improving shoulder strength and ROM.

A Case Series Analysis of Major Vascular Revascularization.

PurposeAtherosclerosis is a generalized disorder and can begin to develop in the abdominal aorta by the second decade of life. The nature of these lesions in coronaries and aorta is atheromatous and less sclerotic when compared to peripheral arteries. A broad spectrum of presentations and different types of lesions demand a personalized approach for the best outcome. This study is a case series analysis of major vascular revascularization. We aim to study various revascularization surgeries and underline the wide range of vascular lesions to which it is applied.MethodsThis is a study based on accrual patient records of all major vascular revascularization surgical/interventional procedures conducted at a tertiary care center for one year.ResultsA total of 110 patients were operated on for vascular diseases. Among these, 86 (78.81%) were men, and 24 (21.81%) were women. The femoropopliteal segment (n=47) was most commonly involved, followed by the common carotid artery (n=20). Atherosclerosis was the main cause of vascular occlusion (81.8%), followed by aneurysm of the aorta (14.5%) and coarctation of the aorta (2.7%). Smoking (62.2%) accounted to be the leading risk factor, followed by hypertension, diabetes, and hyperlipidemia. The majority of patients had a good outcome (92.7%). Minor complications (7.3%) include seroma formation and wound infection, which were managed conservatively. The repair was performed by autologous vein graft in 30% of patients and by synthetic polytetrafluoroethylene (PTFE) graft in 70% of patients. Carotid artery stenting was the most common endovascular procedure performed (n=5). Femoropopliteal bypass grafting was the most common procedure, followed by carotid endarterectomy (n=20) and aortofemoral bypass (n=14).ConclusionThe application of novel techniques such as cavo-atrial shunt in Budd-Chiari syndrome calls attention to the broadened scope of vascular surgery, and the modification of the conventional method of the carotid endarterectomy underscores the evolution of vascular revascularization. Our study thus highlighted that a wide spectrum of vascular lesions ranging from carotid artery stenosis to extensive below-knee disease, either atherosclerotic or aneurysmal, can be successfully treated with surgical revascularization techniques.

Biomechanical Comparison of Synthetic Polytetrafluoroethylene (PTFE) vs Human Dermal Allograft (HDA), 2 vs 3 Glenoid Anchors, and Suture vs Minitape in Superior Capsule Reconstruction.

Background: Superior capsule reconstruction (SCR) is an option for the treatment of massive, irreparable rotator cuff tears. However, which materials yield the strongest constructs remains undetermined. Purposes: We sought to investigate whether SCR with polytetrafluoroethylene (PTFE) or human dermal allograft (HDA), 2 or 3 glenoid anchors, and suture or minitape resulted in better failure load properties at the patch-glenoid interface. Methods: We conducted a biomechanical study in 30 glenoid-sided SCR repairs in Sawbones models divided into 5 groups. Each was pulled to failure to assess mode of failure, peak load (N), stiffness (N/mm), yield load (N), peak energy (N m), and ultimate energy (N m). The 5 groups were as follows: group 1-PTFE, 2 anchors, and suture; group 2-PTFE, 2 anchors, and minitape; group 3-HDA, 2 anchors, and suture; group 4-HDA, 2 anchors, and minitape; group 5-PTFE, 3 anchors, and minitape. Results: Repairs failed by button-holing of suture/minitape. Group 5 had greater peak load, stiffness, yield load, and peak energy (384 ± 62 N; 24 ± 3 N/mm; 343 ± 42 N; 4 ± 2 N m) than group 3 (226 ± 67 N; 16 ± 4 N/mm; 194 ± 74 N; 2 ± 1 N m) or group 4 (274 ± 62 N; 17 ± 4 N/mm; 244 ± 50 N; 2 ± 1 N m) and greater ultimate energy (8 ± 3 N m) than all other groups. Conclusions: This biomechanical study of SCR repairs in Sawbones models found that yield load was greater in PTFE than HDA, 3 anchors were better than 2, and minitape was no better than suture.

Modified Cabrol technique for the treatment of adult anomalous left coronary artery from the pulmonary artery

BackgroundAnomalous left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital anomaly that typically presents within the first year of life but can also sporadically present in adults. ALCAPA, if left untreated, can lead to coronary ischemia and sudden death.Case presentationWe present the case of a 32-year-old male with ALCAPA with ischemic cardiomyopathy and the anomalous left main coronary originating from the non-facing sinus of the pulmonary artery (PA). A posterior reimplantation of the anomalous coronary artery was accomplished with a modified Cabrol technique using synthetic polytetrafluoroethylene (PTFE) graft.ConclusionsA posterior re-implantation technique using a modified Cabrol graft, in cases where length of the native button is challenging, has excellent outcomes for this rather rare and challenging clinical entity.

Thoracoscopic pericardial patch repair of iatrogenic major bronchial injury during oesophagectomy.

Tracheobronchial injuries are rare but dreaded and potentially lethal complications of oesophagectomy. The reported literature on tracheobronchial injuries in thoraco-laparoscopic oesophagectomy is sparse. They may be detected either intraoperatively or in the post-operative period. Those tracheobronchial injuries detected intraoperatively usually need conversion to an open procedure for appropriate management. The surgical approaches and the methods employed for closure depend on the size and location of the rent. The methods of surgical repair include primary closure, gastric patch closure, pericardial patch, pleural patch, pedicled intercostal muscle flap, dural graft and synthetic polytetrafluoroethylene grafts. Herein, we report a thoracoscopic repair of a major bronchial injury encountered in a patient during thoracoscopic oesophagectomy using a pericardial patch. To the best of our knowledge, this is the first report of a thoracoscopic repair of a bronchial injury using a pericardial patch.

Hybrid approach of arterial allograft application in reconstructive surgery of the great arteries

The article presents a case of a hybrid intervention using an arterial allograft on the great arteries of the lower extremities in a patient with chronic limb threatening ischemia and prosthetic infection. The patient has a history of repeated operations using synthetic polytetrafluoroethylene and dacron prostheses. In the early postoperative period, a clinical presentation of the prosthesis bed suppuration developed. The article shows the main phases of patient treatment: removal of synthetic prostheses, transplantation of the donor femoral artery, and balloon angioplasty of the popliteal and anterolateral arteries. In the postoperative period, blood circulation in the lower limb is fully compensated, and the dorsal pedis artery pulse is determined. Wounds were healed by primary intention. At the control visit after 6 months, no adverse events were revealed; according to the data of duplex scanning, the main blood flow in the arteries of the leg was recorded, the blood circulation was fully compensated. Thus, hybrid intervention using arterial allograft and balloon angioplasty of the popliteal and anterolateral tibial arteries proved to be an effective method of treatment in the current clinical situation.

Movement Patterns of the Shoulder Post Synthetic Interpositional PTFE Patch Repair for Large Rotator Cuff Tears

The use of a synthetic polytetrafluoroethylene patch to repair large rotator cuff tears has resulted in good postoperative outcomes with respect to strength and range of motion. However, there is little information evaluating the movement patterns of the shoulder after patch repair. Following a reli

Reaction of connective tissue of arterial and venous walls to implantation of synthetic and biological grafts

30% of patients in the remote period appear to develop restenosis of the anastomoses formed during reconstructive-restorative operations on vessels. Two major causes of restenosis have been determined: intimal hyperplasia and smooth muscle cell proliferation. The reaction of connective-tissue elements of vascular walls in response to implantation of grafts remains unstudied. The study was undertaken to examine the reaction of connective tissue of the arterial and venous walls to implantation of synthetic and biological grafts. We analysed the results of an experimental study performed on a total of 60 rabbits divided into 4 groups each consisting of 15 animals: in the first 2 groups we examined tissue reaction to implantation of synthetic and biological grafts on the wall of an artery and in the remaining 2 groups - on the wall of a vein. The synthetic grafts were made of polytetrafluoroethylene, with the biological ones made of bovine internal thoracic arteries. The portions of the vessels along with the implanted grafts were subjected to histological examination on postoperative days 14, 21 and 30. The specimens were studied by means of light microscopy after haematoxylin-eosin staining. We also carried out a morphometric study consisting in determining the quantitative ratio of the cellular composition of connective tissue. After implantation on the arterial wall, the connective-tissue capsule under the synthetic prosthesis was 1.8 times thicker than under the biological one, with predominance of the cellular component over fibrous one, which deformed the zone of implantation. Under the biological prosthesis, the capsule on the arterial wall was presented by fibrous structures with no deformation of the zone of implantation. The reparative reaction of the venous wall to implantation of the synthetic prosthesis was represented by a thin fibrous connective-tissue capsule. The reaction of the venous wall to the biological transplant was at all terms of the experiment characterised by significant inflammatory alterations with granulomatosis and immunomorphological shifts with formation of lymphoid follicles on the border with the transplant. Implantation of the synthetic polytetrafluoroethylene prosthesis on the arterial wall induced a hyperplastic reaction of the elements of connective tissue, and a normoplasic one on the venous wall. Implantation of the biological prosthesis on the arterial wall did not induce proliferation of connective-tissue elements, and on the venous wall - granulomatous inflammation.

Aortic aneurysm: A life-threatening condition in a low-resource nation

Background: Aortic aneurysm is said to be uncommon in the black population; however, with the modification in lifestyle of the dark-skinned people, and improved diagnostic facilities in Sub-Saharan African nations, a surge in its presentation is more likely. If undiagnosed, aortic aneurysm can be catastrophic. We determined the epidemiology pattern and outcome of aortic aneurysm at our institution. Materials and Methods: This is a retrospective analysis of patients who presented with aortic aneurysm from 2000 to 2017. A pro forma was designed to analyze the bio data, characteristics of the aneurysms, clinical manifestation, treatment, and outcome. The Crawford, Stanford, and DeBakey criteria were used to classify the aortic aneurysm. The surgical management of the aneurysm was resection and its replacement with synthetic polytetrafluoroethylene prosthesis with antibiotic prophylaxis under general anesthesia. Results: A total of 17 patients were recruited, with a mean age of 62.75 ± 20.92 years. A high proportion were above 65 years, i.e., 7 (41.2%), and male gender, i.e., 10 (58.8%). The most common location of aortic aneurysm using Crawford criteria was Type IV followed by Type I, with Stanford criteria being Stanford Type B (13) and with DeBakey being Type III (3). Five operated were fusiform in shape. A higher proportion of patients, i.e., 14 (82.4%), had coexisting hypertension, and a positive history of smoking, i.e., 7 (41.2%). The 30-day mortality was 64.7%, the operative mortality was 35.3%, and three patients (17.6%) were loss to follow-up. A positive history of smoking increased the risk of dead, relative risk 3.375, 95% confidence interval 0.677–5.909, P = 0.04. Conclusion: Aortic aneurysm, though uncommon, is not a rare disease among cardiovascular disorders in a low-resource environment. The most common shape and location were fusiform and Stanford Type B or DeBakey Type III, respectively. There was associated high 30-day mortality (64.7%).

Evaluating the Outcomes of Rotator Cuff Repairs With Polytetrafluoroethylene Patches for Massive and Irreparable Rotator Cuff Tears With a Minimum 2-Year Follow-up

Background: Massive and irreparable rotator cuff tears are difficult to manage surgically. One technique is to use a synthetic polytetrafluoroethylene (PTFE) patch to bridge the tear. However, there is little information regarding the outcomes of this procedure. Purpose: To determine the ≥2-year outcomes of patients for whom synthetic patches were used as tendon substitutes to bridge irreparable rotator cuff defects. Study Design: Case series; Level of evidence, 4. Methods: This retrospective cohort study used prospectively collected data. Patients included those with a synthetic patch inserted as an interposition graft for large and/or irreparable rotator cuff tears with a minimum 2-year follow-up. Standardized assessment of shoulder pain, function, range of motion, and strength was performed preoperatively, at 6 and 12 weeks, and at 6 months and ≥2 years. Radiograph and ultrasound were performed preoperatively, at 6 months, and ≥2 years. Results: At a mean of 36 months, 58 of 68 eligible patients were followed up, and 53 of 58 (90%) patches remained in situ. Three patches failed at the patch-tendon interface, while 1 patient (2 shoulders/patches) went on to have reverse total shoulder replacements. Patient-ranked shoulder stiffness (P < .001), frequency of pain with activity and sleep (P < .0001), level of pain at rest and overhead (P < .0001), and overall shoulder function improved from bad to very good (P < .0001) by 6 months. Supraspinatus (mean ± SEM: 29 ± 16 N to 42 ± 13 N) and external rotation (39 ± 13 N to 59 ± 15 N) strength were the most notable increases at the ≥2-year follow-up (P < .0001). Passive range of motion also improved by 49% to 67%; forward flexion, from 131° to 171°; abduction, from 117° to 161°; external rotation, from 38° to 55°; and internal rotation, from L3 to T10 (P < .0001) preoperatively to ≥2 years. The most improvement in passive range of motion occurred between 12 months and ≥2 years. The mean (SD) Constant-Murley score was 90 (12), while the American Shoulder and Elbow Surgeons score was 95 (8). Conclusion: At 36 months postoperatively, patients who had synthetic patches used as tendon substitutes to bridge irreparable rotator cuff defects reported less pain and greater overall shoulder function as compared with preoperative assessments. They demonstrated improved range of passive motion and improved strength. The data support the hypothesis that the technique of using a synthetic PTFE patch to bridge a large and/or irreparable tear has good construct integrity and improves patient and clinical outcomes.

A Comparison of Two Arthroscopic Techniques for Interpositional Polytetrafluoroethylene Patch Repair for Massive Irreparable Rotator Cuff Tears: Speed and Biomechanics.

Interpositional synthetic patch repairs are a novel method of treating massive irreparable rotator cuff tears. However, surgeons experience difficulty in the arthroscopic insertion of these patches. We compared two methods of arthroscopic interpositional synthetic patch repair: the newly devised slide-and-grip technique, using pre-loaded sliding knots and no arthroscopic knots, and the weave technique, using less arthroscopic knot tying than the earlier mattress technique. Study questions were as follows: (1) Would the slide-and-grip technique take less time than the weave technique? (2) Would the biomechanical strength of the two methods be comparable? Fourteen paired ovine infraspinatus tendon ex vivo models of the degenerative human rotator cuff underwent timed repair with a synthetic polytetrafluoroethylene (PTFE) patch, using either the weave technique (n = 7) or the slide-and-grip technique (n = 7). Each was pulled to failure using a tensile testing machine, the Instron 8874. The time to complete the slide-and-grip repairs was shorter (12 ± 0.9min) than that of the weave repairs (23 ± 1min). Ultimate load to failure was comparable for the slide-and-grip and weave techniques (211 ± 27N vs. 295 ± 35N, respectively), and the slide-and-grip was less stiff (14 ± 1N/mm vs. 19 ± 1N/mm). The slide-and-grip technique took less time than the weave technique for the interpositional patch repair of massive irreparable rotator cuff tears and when correctly performed had comparable biomechanical strength.

Effectiveness of biological prosthesis for femoro-femoral bypass in high risk patients

To compare synthetic and biological prostheses for femoral bypass surgery. There were 40 patients with critical ischemia of lower extremities due to atherosclerotic lesion of aorto-iliac segment and severe comorbidities. They were divided into 2 groups by 20 patients. C-shaped femoro-femoral bypass with synthetic polytetrafluoroethylene and lavsan prostheses was performed in the first group and S-shaped bypass procedure with biological prosthesis from the internal thoracic arteries of the bull - in the second group. Biological prosthesis is associated with reduced early postoperative morbidity by 10%, late graft thrombosis incidence by 20% and increased physical and psychological health by 7.1%. S-shaped femoro-femoral bypass with a biological prosthesis from the internal thoracic arteries of the bull is pathogenetically substantiated and effective.

Оценка проходимости синтетических кондуитов из пористого политетрафторэтилена при реконструкции магистральных вен (экспериментальное исследование)

Цель - изучение проходимости синтетических кондуитов из пористого политетрафторэтилена при реконструкции магистральных вен и обоснование их применения в клинической практике. Методика. Исследование выполнено на 70 кроликах половозрелого возраста мужского пола породы «Белый новозеландский» массой 3,0-3,5 кг. 40 кроликам выполнено линейное протезирование инфраренального отдела задней полой вены. 30 кроликам выполнено линейное протезирование инфраренального отдела брюшной аорты (группа сравнения). Оперативные вмешательства были выполнены в асептических условиях под внутримышечным наркозом. Для протезирования брюшной аорты и задней полой вены использовали политетрафторэтиленовые протезы (7 поколение, 2010) производства ЗАО «НПК «Экофлон» (Россия) с внутренним диаметром 4,0 мм и длиной 20,0 мм. Все анастомозы формировали атравматическим шовным материалом 7/0 или 8/0 с использованием микроинструментов. На протяжении всего срока эксперимента антикоагулянтной и антиагрегантной терапии не проводилось. В течение всего срока наблюдения контроль проходимости протезов осуществляли ультразвуковой допплерографией скоростных показателей кровотока дистальнее и проксимальнее протеза на сроках 3, 10, 30, 90, 180, 270 сут. На контрольных сроках наблюдения проходимость протеза оценивали прямым инвазивным измерением давления крови, а также интраоперационной ультразвуковой допплерографией линейной скорости кровотока дистальнее и проксимальнее протеза. После вывода животного из эксперимента протез иссекали с окружающими тканями для дальнейшего изучения. При сравнении показателей давления крови и линейной скорости кровотока дистальнее и проксимальнее протеза на разных сроках использовали критерий Манна-Уитни. Критический уровень значимости при проверке статистических гипотез принимался &lt;0,05. Результаты. Статистически значимой разницы линейных скоростей кровотоков и давления крови проксимальнее и дистальнее протеза на всех сроках наблюдения не выявлено. Проходимость протезов из политетрафторэтилена в венозной позиции не отличается от таковой в артериальной позиции. Тромбозов и гемодинамически значимых стенозов синтетических кондуитов из пористого политетрафторэтилена, как в венозной, так и в артериальной позиции не отмечено на всех сроках. Заключение. Проходимость синтетических кондуитов из пористого политетрафторэтилена в венозной позиции сравнима и не отличается от таковой в артериальной позиции. Полученные данные позволяют получить экспериментальное обоснование возможности использования синтетических кондуитов из пористого политетрафторэтилена при реконструкции магистральных вен в клинической практике. Aim. To study patency of synthetic, porous polytetrafluoroethylene (PTFE) conduits in reconstruction of great veins and to justify their use in clinical practice. Methods. The study was conducted on 70 New Zealand male rabbits weighing 3.0-3.5 kg. Infrarenal linear prosthetic reconstruction of posterior vena cava was performed in 40 rabbits. Infrarenal linear prosthetic reconstruction of abdominal aorta was performed in 30 rabbits (control group). All surgical procedures were conducted in aseptic conditions under intramuscular anesthesia. Porous PTFE conduits with 4 mm internal diameter and 20 mm length (7th generation, 2010; ZAO NPK Ecoflon, Russia) were used for prostheses of aorta and posterior vena cava. All anastomoses were made of atraumatic 7/0-8/0 ligature using microsurgical instruments. No anticoagulant therapy was used throughout the experimental period. During the study, conduit patency was controlled by ultrasound Doppler monitoring of blood flow velocity distal and proximal to the conduit and direct, invasive BP measurements during the surgery and at 3, 10, 30, 90, 180, and 270 days of surgery. At the end of experiment, the conduit was removed from the animal together with adjacent structures. The Mann-Whitney U-test was used for comparison of BP and blood flow velocity distal and proximal to the conduit. Differences were considered significant at p ?0.05. Results. Significant differences between values of linear blood flow velocity and BP distal and proximal to the conduit were absent in the entire follow up period. The patency of porous PTFE conduits was similar in both arterial and venous positions. No conduit thrombosis or hemodynamically significant stenosis were observed in arterial or venous positions in the entire follow up period. Conclusion. The patency of PTFE conduits in the venous position is similar to and not different from the arterial position. The obtained experimental data support the use of synthetic PTFE conduits for reconstruction of great veins in clinical practice. Conclusion. The polytetrafluoroethylene conduits patency of in venous position is similar and does not differ from arterial position. Obtained experimental data gives the opportunity for synthetic polytetrafluoroethylene conduits appliance for main vein reconstruction in clinical practice.

A pilot study: Alternative biomaterials in critical sized bone defect treatment

BackgroundCritical-sized bone defects are a significant challenge with limited effective reconstructive options. The Masquelet Technique (MT) offers a solution to help restore form and function. Although this technique has produced promising results; a clear mechanism has not been determined. Theories include that the induced membrane has osteogenic potential or the membrane acts as a physical barrier to prevent fibrous tissue ingrowth. We hypothesize the induced membrane acts primarily as a physical barrier and that a synthetic non-biological membrane will allow a comparable amount of bone volume in the defect site. MethodsTen New Zealand rabbit forelimbs (n=10) were divided into three study groups. A critical sized defect of 3.5cm in the ulna was created. In the control group, a traditional MT was performed (n=4). The experimental arm varied by replacement of the PMMA with a non-porous (n=3) or porous (150um) (n=3) polytetrafluoroethylene (PTFE) membrane filled with allograft. Micro-CT analysis was done to compare bone volume to tissue volume ratios (BV/TV). Defect sections were examined histologically with alkaline phosphatase (ALP), tartrate-resistant acid phosphatase (TRAP) and von kossa (VK) staining. ResultsMicroCT analysis comparing BV/TV between the control and experimental arms showed no difference. BV/TV of the MT was 7.77%±2.34 compared to porous 9.12%±3.66 and nonporous 9.76%±1.57 PTFE membranes (p1=0.761, p2=0.572, respectively). Histological sections from both samples stained for ALP and TRAP displayed osteoblastic and osteoclastic activity. There was a higher amount of ALP and TRAP positively stained cells near the native bone ends in comparison to the center of the defect, in both sample types. Conclusion and significanceReplacing the induced membrane from the MT with a synthetic PTFE membrane illustrated that the membrane acts primarily as a functional barrier. Compared to the induced membrane, the PTFE membrane was able to display similar osteointegrative properties. These results allow for future optimization of the technique with the potential to further streamline towards a single stage procedure.

Tissue reaction to the implantation of the venous wall of synthetic and biological prosthesis

АктуальностьДо настоящего времени в сосудистой хирургии сохраняется проблема выбора трансплантата для шунти-рования.Цель исследованияСравнить тканевую реакцию венозной стенки на имплантацию синтетического и биологического про-тезов.Материалы и методыПроведен анализ экспериментального исследования, выполненного на 30 кроликах, разделенных надве опытные группы по 15 особей в каждой. В первой группе в стенку нижней полой вены имплантировался синтетическийполитетрафторэтиленовый протез, во второй – биологический протез из внутренних грудных артерий быка. Участкинижней полой вены в месте с имплантированным протезом подвергались гистологическому исследованию на 14, 21 и 30-есутки после операции. Препараты изучались при световой микроскопии после окраски гематоксилин-эозином. Проводи-лось морфометрическое исследование, заключающееся в определении количественного соотношения клеточного составасоединительной ткани.Результаты и их обсуждениеВоспалительная реакция венозной стенки на синтетический протез на 14-е сутки в 1,14раза, на 21-е сутки – в 1,53 раза, а на 30-е сутки – в 1,52 менее выражена, чем на имплантацию биологического протеза.Реакция на биологический трансплантат стенки вены на 14-е сутки и, в последующем, на 30-е сутки выражена очень силь-но и представлена как значительными воспалительными изменениями с гранулематозом, так и иммуноморфологическимисдвигами с образованием на границе с трансплантатом лимфоидных фолликулов.ЗаключениеПри бедренно-подколенном шунтировании ниже щели коленного сустава при отсутствии адекватной по диа-метру аутовены следует применять комбинированный синтетический политетрафторэтиленовый протез с аутовеноз-ной вставкой в области дистального анастомоза

Matrix metalloproteinases and risk stratification in patients undergoing surgical revascularisation for critical limb ischaemia.

Critical limb ischaemia (CLI) is the most advanced form of peripheral artery disease (PAD) and it is often associated with foot gangrene, which may lead to major amputation of lower limbs, and also with a higher risk of death due to fatal cardiovascular events. Matrix metalloproteinases (MMPs) seem to be involved in atherosclerosis, PAD and CLI. Aim of this study was to evaluate variations in MMP serum levels in patients affected by CLI, before and after lower limb surgical revascularisation through prosthetic or venous bypass. A total of 29 patients (7 females and 22 males, mean age 73·4 years, range 65-83 years) suffering from CLI and submitted to lower extremity bypass (LEB) in our Institution were recruited. Seven patients (group I) underwent LEB using synthetic polytetrafluoroethylene (PTFE) graft material and 22 patients (group II) underwent LEB using autogenous veins. Moreover, 30 healthy age-sex-matched subjects were also enrolled as controls (group III). We documented significantly higher serum MMPs levels (P < 0·01) in patients with CLI (groups I and II) with respect to control group (group III). Finally, five patients with CLI (17·2%) showed poor outcomes (major amputations or death), and enzyme-linked immunosorbent assay (ELISA) test showed very high levels of MMP-1 and MMP-8. MMP serum levels seem to be able to predict the clinical outcomes of patients with CLI.

Treatment of vitamin D deficiency/insufficiency with ergocalciferol is associated with reduced vascular access dysfunction in chronic hemodialysis patients.

Vitamin D deficiency or insufficiency is highly prevalent among patients with chronic kidney disease (CKD). This study aims to determine the relationship between vitamin D and frequency of vascular access dysfunction (VAD) in hemodialysis (HD) patients. We reviewed medical records of all HD patients who had serum 25-hydroxyvitamin D (25OHD) levels at 4 outpatient dialysis facilities between January 2011 and January 2012. Patients were included if they were ≥18 years of age, had been on maintenance dialysis for ≥3 months, and had native arteriovenous fistula or synthetic polytetrafluoroethylene grafts for dialysis access. Patients with catheters were excluded. 25-Hydroxyvitamin D levels <30 ng/mL were documented in 183 patients (86%). Median and interquartile range [Q1, Q3] of 25OHD level was 16 [11, 25] ng/mL. Among 213 dialysis patients, 102 had VAD. Median 25OHD level was significantly lower in patients who had VAD than in those without VAD (14.5 [10, 22] vs. 19 [12, 27.5] ng/mL; P = 0.003). There was significant association between VAD and the lowest quartile relative to the highest quartile of 25OHD level. A 25OHD level <12 ng/mL was associated with more than doubling of risk for VAD (OR 2.56; 95% CI [1.05-6.23], P < 0.05). Of 213 patients, 140 were treated with ergocalciferol and 73 were not treated. Treatment was associated with significant reduction in VAD (OR = 0.36; 95% CI [0.19-0.68], P = 0.002). Vitamin D deficiency or insufficiency is an independent risk factor for VAD in HD patients; its treatment with ergocalciferol is associated with decreased VAD.

Egg White Varnishes on Ancient Paintings: A Molecular Connection to Amyloid Proteins

AbstractFor about 400 years, egg white was used to coat and protect paintings without detailed understanding of its molecular properties. A molecular basis is provided for its advantageous properties and one of its protective properties is demonstrated with oxygen transport behavior. Compared to the native secondary structure of ovalbumin in solution of circa 33 % α‐helix and β‐sheet, attenuated total reflection–FTIR (ATR‐FTIR) spectra showed a 73 % decrease of α‐helix content and a 44 % increase of β‐sheet content over eight days. The data suggest that the final coating of dissolved ovalbumin from egg white after long exposure to air, which is hydrophobic, comprises mostly β‐sheet content (ca. 50 %), which is predicted to be the lowest‐energy structure of proteins and close to that found in amyloid fibrils. Coating a synthetic polytetrafluoroethylene membrane with multiple layers of egg white decreased oxygen diffusion by 50 % per layer with a total decrease of almost 100 % for four layers.