Expanded Polytetrafluoroethylene Conduit Research Articles

Investigation of a chronic single-stage sheep Fontan model

ObjectivesOur goal was to conduct a hemodynamic analysis of a novel animal model of Fontan physiology. Poor late-term outcomes in Fontan patients are believed to arise from Fontan-induced hemodynamics, but the mechanisms remain poorly understood. Recent advances in surgical experimentation have resulted in the development of a chronic sheep model of Fontan physiology; however, detailed analysis of this model is lacking. MethodsWe created a single-stage Fontan model in juvenile sheep with normal biventricular circulation. The superior vena cava was anastomosed to the main pulmonary artery, and the inferior vena cava was connected to the main pulmonary artery using an expanded polytetrafluoroethylene conduit. Longitudinal hemodynamics, including catheterization and magnetic resonance imaging were evaluated. ResultsFour out of 12 animals survived, with the longest surviving animal living 3 years after single-stage Fontan. We showed a significant era effect regarding survival (1 out of 8 and subsequently 3 out of 4 animals surviving beyond 2 months) attributed in large part to the procedural learning curve. Key characteristics of Fontan hemodynamics, namely systemic venous hypertension and low normal cardiac output, were observed. However, recapitulation of passive human Fontan hemodynamics is affected by volume loading of the right ventricle given an anatomic difference in sheep azygous venous anatomy draining to the coronary sinus. ConclusionsA significant learning curve exists to ensure long-term survival and future surgical modifications, including banding of the main pulmonary artery and ligation of the azygous to coronary sinus connection are promising strategies to improve the fidelity of model hemodynamics.

Surgical Deep Vein Arterialization: Adding to the Armamentarium of Complex Limb Salvage

Patients with severe peripheral arterial disease with limited or nonexistent arterial runoff, the so-called "desert foot", challenge efforts at limb preservation. Deep vein arterialization (DVA) involves incorporating a venous target as an outflow to achieve revascularization in these complex patients. We report outcomes in an initial series of patients undergoing DVA as a component of surgical bypass. Over a 2-year period, 10 patients underwent bypass incorporating DVA due to severely disadvantaged runoff using a heparin-bonded expanded polytetrafluoroethylene conduit. Indications for surgery included tissue loss (8) or ischemic rest pain (2) in patients who had failed endovascular (3) or surgical (7) revascularization. Inflow arteries for bypass ranged from external iliac to below knee popliteal. Outflow anastomoses incorporated a common ostium arteriovenous fistula between anterior tibial (5), posterior tibial (2), peroneal (1) or plantaris pedis (2) arteries, and corresponding tibial veins. Prior to anastomotic completion, tibial vein valves were lysed to allow venous arterialization by a way of retrograde flow. Postoperative medical regimen included dual antiplatelet (2), antiplatelet plus anticoagulation (7), or anticoagulation alone (1). Primary patency was maintained in 7 of 10 grafts (average: 4.1 months, range: 1-18 months). Limb salvage was achieved in 8 of 10 patients (average: 6 months, range: 1-18 months). Two below knee amputations were performed after graft occlusion due to extensive tissue loss and infection, whereas 1 patient maintained limb salvage despite graft occlusion after successful wound healing. This initial experience describes surgical DVA using a prosthetic conduit in conjunction with an arteriovenous fistula at the distal anastomosis in patients with threatened limb loss and severely disadvantaged tibial runoff. Although evidence for long-term efficacy is uncertain, preliminary outcomes warrant further investigation as this technique may allow for surgical revascularization resulting in limb preservation for patients with no other alternative than amputation.

Aspergillus Calidoustus Endocarditis in a Child after Cardiac Surgery: Case Report

We report a case of a 14-year-old male with Aspergillus calidoustus endocarditis occurring in an expanded polytetrafluoroethylene conduit for Tetralogy of Fallot. Aspergillus calidoustus is a concerning newly described species that is often resistant to voriconazole. Our patient was optimally treated by using antifungal therapy active against the fungus and surgical resection of the infected tissue.

Effectiveness and Safety of Rivaroxaban Compared to Acenocumarol after Infrainguinal Surgical Revascularization

Optimal antithrombotic therapy after lower limb infrainguinal revascularization remains a controversial topic. The use of anticoagulants, alone or in combination with antiplatelet drugs, can potentially improve patency rate and limb salvage, particularly in patients with risk factors for early thrombosis. Bleeding is the main complication of long-term anticoagulant use. New oral anticoagulants can represent an attractive alternative to the standard vitamin K antagonists. The objective of the study is to evaluate the effectiveness (bypass occlusion and major amputation) and safety (major bleeding and all-cause mortality) of rivaroxaban compared to acenocumarol after infrainguinal lower limb surgical revascularization. Retrospective cohort study of patients with peripheral arterial disease submitted to lower limb infrainguinal bypass revascularization with vein or expanded polytetrafluoroethylene conduit, who were anticoagulated with acenocumarol or rivaroxaban after hospital discharge. Patients with proximal revascularization, revascularization due to any pathology other than peripheral arterial disease, coagulation disorder, stroke or acute myocardial infarction in less than 30days, glomerular filtration rate <15mL/min, or on hemodialysis were excluded. One hundred nine patients were included (78.9% male), with a mean age of 64.8years. After hospital discharge, 40 patients (36.7%) were medicated with rivaroxaban and 69 patients (63.3%) with acenocumarol. At 1year of follow-up, patients under rivaroxaban and acenocumarol presented comparable major amputation rates (12.5 % vs. 10.1%, P=0.756), bypass occlusion (22.5% vs. 24.6 %, P=0.769), and mortality rate (10% vs. 8.7%, P=0.756). Major bleeding occurred in 13.8% of patients. Patients with renal dysfunction had significantly higher bleeding risk with acenocumarol (45.5% vs. 0%, P=0.028) compared to rivaroxaban, while patients with normal renal function presented similar bleeding rates with both anticoagulants (6.1% vs. 6.4%, P=0.953). Rivaroxaban has equivalent effectiveness to acenocumarol after infrainguinal bypass revascularization, with similar occlusion, major amputation, and mortality rates. Rivaroxaban has an improved safety profile in patients with moderate renal dysfunction due to a significantly lower incidence of major bleeding. In patients with normal renal function, rivaroxaban and acenocumarol present equivalent major bleeding rates.

Modification of expanded polytetrafluoroethylene valved conduit using the thin-type leaflets

ObjectivesThe expanded polytetrafluoroethylene conduit with fan-shaped leaflets and bulging sinuses for right ventricular outflow tract reconstruction was modified with a newly developed thin-type expanded polytetrafluoroethylene leaflet. The purpose of this study was to evaluate the clinical outcomes and hemodynamic performance of the modified conduit. MethodsFrom January 2010 to December 2013, 149 patients underwent definitive right ventricular outflow tract reconstruction using the expanded polytetrafluoroethylene conduit; the 55 patients receiving a conventional conduit (group N) were compared with the 94 patients receiving a modified conduit (group T). ResultsThere were no conduit-related deaths, operative deaths, or reimplantations for conduit failure. The overall survival and freedom from reintervention for conduit-related reasons at 3 years were 98.2% versus 95.6% (P = .438) and 94.7% versus 97.9% (P = .954) for groups N and T, respectively. The mean peak pressure gradients were 22.6 ± 15.6 mm Hg versus 18.2 ± 11.5 mm Hg (P = .161), and in the subanalysis within small-sized conduits, they were 30.2 ± 16.5 mm Hg versus 20.4 ± 10.7 mm Hg (P = .034). Regarding conduit insufficiency, the modified conduit showed a significantly worse grade of insufficiency (P = .014) only in the subanalysis within large-sized conduits. ConclusionsAlthough the clinical outcomes did not differ within midterm observation, the thin-type expanded polytetrafluoroethylene leaflet was considered to be suitable for the small-sized conduits, but not for large-sized conduits, based on the comparison of the hemodynamic performance. Long-term follow-up is necessary to address the appropriate sheet type for middle-sized conduits and to estimate the durability of the thin-type leaflet.

Pulmonary annular motion velocity reflects right ventricular outflow tract function in children with surgically repaired congenital heart disease.

Right ventricular (RV) dysfunction is generally evaluated using analyses of tricuspid annular motion. However, it represents only one aspect of RV performance. Whether measuring pulmonary annular motion velocity could serve as a novel way to evaluate global RV and/or RV outflow tract (RVOT) performance in pediatric congenital heart disease (CHD) patients with surgically repaired RVOT was evaluated. In this prospective study, tissue Doppler-derived pulmonary annular motion velocity was measured in children (aged 2-5years) with RVOT reconstruction (RVOTR group, n=48) and age-matched healthy children (Control, n=60). The types of RVOTR procedures were as follows: pulmonary valve-sparing procedure (PVS, n=7); transannular patch with monocusp valve reconstruction (TAP, n=29); and RV-to-PA conduit reconstruction using a pericardial valve with expanded polytetrafluoroethylene conduit (Rastelli, n=12). Pulmonary annular motion velocity waveforms comprised systolic bimodal (s1' and s2') and diastolic e' and a' waves in all participants. The peak velocities of s1', s2', e', and a' were significantly lower in the RVOTR group than in the control group (all p<0.0001). Furthermore, these parameters depended significantly on the type of surgical procedure. The peak velocities of s1', s2', and e' had significant correlations with RVOT ejection fraction (RVOT-EF) (r=0.56, 0.49, and 0.34, respectively), and RVOT fractional shortening (RVOT-FS) (r=0.72, 0.55, and 0.41, respectively), although there were no significant correlations between pulmonary annular motion and global RV function, including RV ejection fraction (RVEF) and RV fractional area change (RVFAC) in the assessment of all RVOTR group patients. The pulmonary annular motion parameters in the PVS group had significant correlations with both global RV and RVOT performance. The TAP group showed significant correlations between RVOT function and pulmonary annular motion. The Rastelli group showed almost no significant correlations between RV/RVOT function and tissue Doppler parameters. Pulmonary annular motion velocity is a simple, rapid, reproducible, and useful method of assessing RVOT function in children with surgically repaired CHD.

30-year experience of Fontan surgery: single-centre\u2019s data

BackgroundThe Fontan procedure has been modified several times since it was introduced into practice in 1968. As many patients now survive to adulthood, attention is directed towards their clinical status and late morbidity. We report our surgical experience of 30 years in Fontan procedures.MethodsFrom January 1985 to January 2015, 80 patients underwent Fontan surgery. Twenty-one patients received an atrio-pulmonary Fontan (Group I), four patients underwent total cavopulmonary connection (TCPC) with an intra-atrial lateral tunnel (Group II), six patients received extra-cardiac TCPC with an aortic homograft (group III) and 49 patients received extra-cardiac TCPC with an expanded polytetrafluoroethylene conduit. They were followed for early and late mortality, long-term survival, postoperative morbidity and reoperations.ResultsThe mean follow-up time was 7.4 ± 6.6 years. The Kaplan–Meier estimated 15-year survival rate was 42% in Group I, 50% in Group II, 83% in Group III and 94% in Group IV. The median length of stay in intensive care unit, intubation and chest drain stay time were 90 h (IQR, 46–119), 8 h (IQR, 6–16) and 18 days (IQR, 12–28) respectively. Early complications were bleeding (6), taken down of Fontan circulation (3) and acute heart failure managed by left heart bypass (1). Late-occurring morbidities included arrhythmias (6), protein-losing enteropathy (2), thromboembolism (2) and tracheal stenosis (1). Fourteen patients (18%) had redo Fontan procedures.ConclusionOur series showed improving results after Fontan completion with excellent mid-term outcome after extra-cardiac TCPC with expanded polytetrafluoroethylene conduit. The long-term result should be followed.

Outcome of Right Ventricle to Pulmonary Artery Conduit for Biventricular Repair

The objective of this study was to assess the outcomes of the right ventricle to pulmonary artery conduit for biventricular repair. This is a retrospective review of all right ventricle to pulmonary artery conduit operations for biventricular repair of congenital heart disease between 1982 and 2013 at a single institution. Results were compared among the conduit size and materials. A total of 476 physiologic right ventricle to pulmonary artery conduit operations were identified, with 195 pulmonary homografts, 105 handmade valved expanded polytetrafluoroethylene conduits, 103 Medtronic Hancock (Minneapolis, MN) bioprosthetic valved conduits, 38 non-valved expanded polytetrafluoroethylene tubes, and 35 others. The actuarial survival was 92.4% and the freedom from conduit reoperation was 33.0% at 20 years. The freedom from conduit reoperation was significantly different among conduit materials (76.8%, 92.1%, 81.9%, 80.6%, and 63.8% for pulmonary homograft, valved expanded polytetrafluoroethylene conduit, Hancock conduit, non-valved expanded polytetrafluoroethylene tube, and others at 5 years, p= 0.0001). The Cox proportional hazards model showed that age (p < 0.001 and p= 0.04), preoperative diagnosis (p < 0.001 and p < 0.001), conduit size (p < 0.001 and p < 0.001), and conduit material (the valved expanded polytetrafluoroethylene conduit versus combined other materials; p= 0.01 and p= 0.02, respectively) were significant factors for the freedom from conduit reoperation both when treating conduit size as a categoric predictor and as a quantitative predictor. The handmade valved expanded polytetrafluoroethylene conduit showed excellent early outcome as a right ventricle to pulmonary artery conduit forbiventricular repair. A longer follow-up and a randomized study will be necessary to explore the advantages of the valved expanded polytetrafluoroethylene conduit.

Biodegradable, thermoplastic polyurethane grafts for small diameter vascular replacements

Biodegradable vascular grafts with sufficient in vivo performance would be more advantageous than permanent non-degradable prostheses. These constructs would be continuously replaced by host tissue, leading to an endogenous functional implant which would adapt to the need of the patient and exhibit only limited risk of microbiological graft contamination. Adequate biomechanical strength and a wall structure which promotes rapid host remodeling are prerequisites for biodegradable approaches. Current approaches often reveal limited tensile strength and therefore require thicker or reinforced graft walls. In this study we investigated the in vitro and in vivo biocompatibility of thin host-vessel-matched grafts (n=34) formed from hard-block biodegradable thermoplastic polyurethane (TPU). Expanded polytetrafluoroethylene (ePTFE) conduits (n=34) served as control grafts. Grafts were analyzed by various techniques after retrieval at different time points (1week; 1, 6, 12months). TPU grafts showed significantly increased endothelial cell proliferation in vitro (P<0.001). Population by host cells increased significantly in the TPU conduits within 1month of implantation (P=0.01). After long-term implantation, TPU implants showed 100% patency (ePTFE: 93%) with no signs of aneurysmal dilatation. Substantial remodeling of the degradable grafts was observed but varied between subjects. Intimal hyperplasia was limited to ePTFE conduits (29%). Thin-walled TPU grafts offer a new and desirable form of biodegradable vascular implant. Degradable grafts showed equivalent long-term performance characteristics compared to the clinically used, non-degradable material with improvements in intimal hyperplasia and ingrowth of host cells.

右室流出路再建 ―Fan─shaped ePTFE valveとbulging sinus付きePTFE conduitの有用性―

右室流出路再建 ―Fan─shaped ePTFE valveとbulging sinus付きePTFE conduitの有用性―

Expanded polytetrafluoroethylene conduits and patches with bulging sinuses and fan-shaped valves in right ventricular outflow tract reconstruction: Multicenter study in Japan

There is no optimal substitute for right ventricular outflow tract (RVOT) reconstruction in congenital heart defects. Expanded polytetrafluoroethylene (ePTFE) valved conduits and patches may be a good alternative to homografts and bovine jugular veins. We have developed a fan-shaped ePTFE valve and an ePTFE valved conduit and patch with bulging sinuses with the aim of enhancing the long-term valve function. Bulging sinuses were constructed on ePTFE conduits and patches as described previously (J Thorac Cardiovasc Surg. 2007;134:327-32). Between February 2001 and January 2011, 794 patients (aged 14 days to 56.8 years old; median, 2.0 years old) had ePTFE valves implanted for RVOT reconstruction at 52 Japanese institutes. Conduits with a fan-shaped ePTFE valve were implanted in 325 patients and a patch with a fan-shaped ePTFE valve was implanted in 469 patients. Valve function was assessed by a series of echocardiograms postoperatively. The mean follow-up was 3.6 years (1.1 months to 10.0 years). Freedom from reoperation at 10 years was 95.4% in patients with conduits and 92.3% in those with patches. Pulmonary insufficiency was mild or nonexistent in 95.0% of patients with conduits and 79.6% of patients with patches. The pressure gradient between the right ventricle and the pulmonary artery was 14.0 ± 13.2 mm Hg in patients with conduits and 11.6 ± 11.6 mm Hg in patients with patches. Fan-shaped ePTFE valved conduits and patches with bulging sinuses have a high freedom from reoperation and prevent pulmonary insufficiency. They represent a promising material for RVOT reconstruction.

Infective endocarditis in a child caused by Cardiobacterium hominis after right ventricular outflow tract reconstruction using an expanded tetrafluoroethylene conduit

Cardiobacterium hominis, a member of the HACEK group of organisms, is a rare cause of endocarditis. We report a case of infective endocarditis caused by C. hominis in a male child who had undergone right ventricular outflow tract (RVOT) reconstruction using an expanded polytetrafluoroethylene conduit for tetralogy of Fallot with pulmonary atresia. Two days before admission, the patient suffered from exertional shortness of breath. Right ventricular hypertension was confirmed and RVOT stenosis was suspected based on the echocardiography findings. A CT scan revealed vegetation above the cusp of the conduit. An emergency operation was performed to avoid a pulmonary embolism due to large friable vegetation. C. hominis was cultured from the blood and the vegetation, prompting a diagnosis of prosthetic valve endocarditis. The patient was discharged after a 6-week course of intravenous ceftriaxone therapy.

Bronchial Migration of a Systemic-Pulmonary Shunt Conduit

Using an expanded polytetrafluoroethylene conduit, a subclavian artery-to-pulmonary artery shunt was created in an infant with tetralogy of Fallot. The postoperative course was complicated by sepsis, shunt occlusion, and pneumonia. Four years later, an obstructive mass was found in the right main bronchus on fluoroscopy and was retrieved on rigid endoscopy, which turned out to be the migrated conduit. This case implies that a vascular conduit anastomosed to a systemic artery can migrate into the airway without bleeding, pseudoaneurysm formation, or host artery occlusion.

Reduced Elastic Mismatch Achieved by Interposing Vein Cuff in Expanded Polytetrafluoroethylene Femoral Bypass Decreases Intimal Hyperplasia

Wall shear stress, arterial wall elasticity, and intimal hyperplasia are related. The aim of this study was to investigate the in vitro mechanical properties of ovine femoral arteries, jugular veins, and expanded polytetrafluoroethylene conduits, and to evaluate postoperative intimal hyperplasia. Arterial, venous, and ePTFE mechanical properties were studied in a circulating loop at isobaric systemic pressures. Histological studies of intimal hyperplasia in ePTFE-bypassed femoral arteries with and without Miller cuffs were performed at the 40th and 120th day. The incremental elastic modulus of veins was significantly higher than that of femoral arteries (P < 0.05), but significantly lower than that of ePTFE graft conduits (P < 0.05). Intimal hyperplasia was significantly less in Miller-cuff-bypassed arteries both at the 40th and 120th day (P < 0.01). The Miller cuff acts as a mechanical adapter enhancing wall shear stress and the elastic matching between ePTFE and the native artery, resulting in an early decrease of intimal hyperplasia.

Expanded polytetrafluoroethylene entubulation of the rabbit inferior alveolar nerve

Objective. The purpose of this study was to evaluate the use of an expanded polytetrafluoroethylene conduit in the treatment of a 6.0-mm gap in the rabbit inferior alveolar nerve and compare the results with those of an autogenous interpositional tibial nerve graft. Study design. The inferior alveolar nerves of 5 adult New Zealand White female rabbits (10 nerves) were exposed bilaterally, and a 6-mm segment of each nerve was resected. On one side, chosen at random, the gap was immediately bridged through use of an 8.0 × 2.0-mm expanded polytetrafluoroethylene conduit; on the other side, the gap was grafted with an autogenous tibial nerve graft. Two randomly selected nerves served as sham-dissected controls. At 15 weeks after surgery, the animals were killed and the entire nerve segments were harvested and prepared according to standard fixation and embedding techniques. The sections were examined histomorphometrically to quantify the degree of axonal regeneration through definition of fascicular number, total fascicular surface area, axonal density, and mean axonal diameter at 3 locations along the repair site. Results. Light microscopic examination revealed the presence of disorganized neural tissue in both groups, with slightly more fibrovascular interfascicular tissue in the expanded polytetrafluoroethylene group. Histomorphometric analysis revealed no significant differences between groups for most of the measured variables. The mean axonal diameter varied between groups, and the fascicular number was greater in the expanded polytetrafluoroethylene group at the middle site. Conclusions. This study demonstrates that regeneration of the inferior alveolar nerve can occur across a 6.0-mm gap through an expanded polytetrafluoroethylene tube with results comparable to those of an autogenous nerve graft, significant donor site morbidity being avoided. The significant differences between groups were probably due to greater containment of regenerating axonal fibers in the expanded polytetrafluoroethylene group. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:292-8)

Wrapped-knitted Dacron and microporous EPTFE conduits for reconstruction of right ventricular outflow tract.

The use of the extracardiac conduit for the right ventricle to main pulmonary artery continuity facilitates repair of a wide variety of complex congenital cardiac malformations. Recently, concern has been directed to the appearance of proliferating and obstructive internal peels. In the present study on 18 mongrel dogs, wrapped-knitted Dacron, expanded polytetrafluoroethylene (EPTFE) and wrapped-knitted Dacron/EPTFE conduits were evaluated in the light of internal linings. Macroscopically, the wrapped-knitted Dacron conduits were covered with a thicker and poorly developed neointima, whereas, EPTFE conduits were internally covered with a thin neointima. Microscopically, the neointima on the former was not well healed, while that of the latter was well developed and anchored. Therefore, the EPTFE conduit seems to be superior to the wrapped-knitted Dacron conduit and EPTFE conduit can be used clinically.