The effect of a venous anastomosis Tyrell vein collar on the primary patency of arteriovenous grafts in patients undergoing hemodialysis

PURPOSE: Vein collars and patches are used at the distal anastomoses of infrainguinal prosthetic grafts to improve graft patency. We initiated a randomized, prospective study to determine whether a Tyrell vein collar at the venous anastomosis of forearm loop arteriovenous grafts (AVGs) would improve patency. METHODS: Patients who required new forearm AVGs were randomized to (1) a standard end-to-side graft-vein anastomosis (control group) or (2) a Tyrell vein collar between the graft and the vein (study group). End points were (1) graft thrombosis, (2) graft removal and ligation, or (3) inadequate graft function. Randomization of 75 subjects was planned. The study was terminated early for ethical reasons. RESULTS: Seventeen patients (eight men, nine women) with a mean age of 52.8 years (range, 31-79 years) had 17 grafts placed (control group, n = 10; study group, n = 7). Comorbidities were not different between the groups (P>.05). Six (86%) of seven study grafts failed by 9 months (mean, 4.6 months). Four (66%) failed study grafts had venous outflow tract stenosis from intimal hyperplasia. This was confirmed at surgery in three and by angiography in one. The 9-month primary patency was 80% for the control group versus 17% for the study group (P =.015). Smaller outflow vein diameter in the study group (P =. 048) did not account for this inferior graft patency. CONCLUSION: A Tyrell vein collar at the venous anastomosis of a forearm AVG resulted in premature graft failure. The use of a Tyrell vein collar may accelerate venous anastomosis intimal hyperplasia.     

Salvage of thrombosed dialysis access grafts with venous anastomosis stents

BACKGROUND: Thrombosis of arteriovenous (AV) grafts caused by stenosis at the venous anastomosis is a well-described problem. Surgical thrombectomy and conventional angioplasty with mechanical thrombectomy have provided good success rates in achieving immediate graft patency but with generally dismal graft survival rates in the range of 11% to 36% at 6 months' follow-up. The role of intravascular stents in patients who have failed angioplasty or surgical revision at the venous anastomosis has not been fully elucidated, particularly in older grafts that have previously undergone multiple procedures. METHODS: In this series, 34 patients had self-expanding nitinol stents placed at the venous anastomosis following graft thrombectomy and angioplasty procedures. Patients were selected for stent placement if conventional angioplasty alone was unsuccessful due to immediate elastic recoil or residual stenosis. All patients were followed after stent placement and evaluated for duration of graft patency and need for repeated endovascular procedures. RESULTS: The average graft age at the time of stent placement was 17.9 months. Eight-eight percent of grafts were functioning at 6 months' follow-up, and 63% of the entire group had survived without the need for additional procedures. Among those with need for repeat interventions, 81% had new lesions outside of the stent, and 57% had new lesions within the stent. In 38% of cases, new stenoses were located both outside and within the stent. Among grafts no longer being used, only 19% of the time was it due to disease recurring within the stent. CONCLUSION: Polytetrafluoroethylene (PTFE) graft longevity is improved when venous anastomosis stenoses are treated with stents in selected cases of older grafts that would have normally undergone abandonment or surgical revision.     

Evaluation of 4-mm to 7-mm versus 6-mm prosthetic brachial-antecubital forearm loop access for hemodialysis: results of a randomized multicenter clinical trial

OBJECTIVE: Prosthetic arteriovenous fistulas for hemodialysis vascular access have a high incidence rate of thrombotic occlusions that result in graft failure. This randomized multicenter study was performed to assess the patency rates and the effect of 4-mm to 7-mm grafts on the development of stenoses. METHODS: A total of 109 patients who needed vascular access for hemodialysis were randomized to receive either 6-mm (n = 57) or 4-mm to 7-mm prosthetic brachial-antecubital forearm loop accesses (polytetrafluoroethylene). Duplex scanning, with measurement of blood flow and peak systolic velocity and detection of stenoses (>50%), was performed at 1, 6, and 12 months after surgery. Clinical data were obtained in a prospective manner and primary, assisted primary, and secondary patency rates were calculated with the Kaplan-Meier life-table analysis. Statistical analysis was performed with the independent samples t test and chi(2) test. RESULTS: At 1 year, patency rates were similar for both 4-mm to 7-mm and 6-mm prostheses (primary, 46% versus 43%; assisted primary, 62% versus 58%; secondary, 87% versus 91%). The incidence rate of thrombotic occlusion was comparable for both groups (0.74/patient-year versus 0.88/patient-year; P >.05). Mean graft flow at 1, 6, and 12 months was 1416 versus 1415 mL/min, 1345 versus 1319 mL/min, and 1595 versus 1265 mL/min (P >.05) for 4-mm to 7-mm and 6-mm grafts, respectively. Also, no differences in peak systolic velocities in any part of the grafts were observed. The percentage of stenoses detected was equal in both groups at 1 year after surgery (27% versus 20%; P >.05). CONCLUSION: A 4-mm to 7-mm tapered prosthetic brachial-antecubital forearm loop access did not reduce the incidence rates of stenoses and thrombotic occlusions compared with a 6-mm prosthetic conduit. Moreover, no differences in patency rates were observed. Therefore, we believe that the 4-mm to 7-mm graft should not be used routinely for hemodialysis vascular access.     

Does an adjuvant AV-fistula improve the patency of a femorocrural PTFE bypass with distal vein cuff in critical leg ischaemia?--a prospective randomised multicentre trial.

INTRODUCTION: A lack of suitable veins can cause serious problems when attempting to revascularise critically ischaemic legs. Prosthetic grafts have much worse patency in the femocrural position, despite the use of distal anastomotic cuffs. The use of adjuvant AV-fistula at the distal anastomosis should increase the graft flow above the thrombotic threshold velocity and thus increase prosthetic graft patency. AIM: The aim of the study was to evaluate the benefit of an adjuvant AV-fistula on the patency of a femorocrural PTFE bypass with a distal vein cuff. MATERIALS AND METHODS: This prospective randomised multicentre trial was conducted in four centres. A total of 59 patients with critical leg ischaemia and no suitable veins for grafting were randomised to receive a femocrural PTFE bypass and distal vein cuff, with or without an adjuvant AV-fistula. Thirty-one patients were randomised to the AV-fistula group (AVFG) and 28 to the control group (CG). Six patients were lost to follow-up during the 2-year study time. RESULTS: There were six immediate occlusions in each treatment group, but half of these were saved by re-operation. The mean postoperative ankle-brachial index (ABI) was 0.85 in the AVFG and 0.94 in the CG. The primary and secondary patency rate at 2 years was 29 and 40% for the AVFG and 36 and 40% for the CG (NS). Leg salvage at 2 years was 65 and 68%, respectively (NS). CONCLUSION: Adjuvant AV-fistula does not improve the patency of a femorocrural PTFE bypass with a distal vein cuff.     

Saphenous vein versus PTFE for above-knee femoropopliteal bypass. A review of the literature.

The autogenous saphenous vein is considered the best bypass graft material for arterial bypasses below the inguinal ligament. However, a synthetic graft or prosthesis is considered an acceptable alternative, especially when the distal anastomosis is situated above the knee. Some studies even suggest that patency rates for vein and synthetic grafts are comparable, whereas others indicate that a vein graft is superior to a prosthetic graft, even above the knee. To test the hypothesis that both vein grafts and synthetic prostheses are equally beneficial in the above-knee position, we performed a systematic review of available studies comparing the patency of saphenous vein and polytetrafluoroethylene (PTFE) as bypass material. English and German medical literature from 1966 to 2002 was searched using Medline, and 25 articles meeting our inclusion and exclusion criteria were selected. The patency of venous bypasses was superior to that of PTFE bypasses at all time intervals studied. After 2 years, the primary patency rate of venous bypasses was 81% as compared to 67% for PTFE bypasses, and after 5 years it was 69 and 49%, respectively. After 5 years, the secondary patency of PTFE bypasses reached 60%. When only randomized trials were considered, venous bypasses were again superior to PTFE bypasses at all intervals studied. After 2 years, the primary patency rate of venous and PTFE bypasses was 80 and 69%, respectively, and after 5 years it was 74 and 39%, respectively. Since both randomized and retrospective studies comparing venous with PTFE bypasses showed that vein grafts were 'better' than PTFE prostheses, the null hypothesis that there is no difference between the two types of graft material was rejected (p=0.008). We conclude from this systematic review that if a saphenous vein is available, a venous bypass should be chosen at all times, even if patients have an anticipated short life expectancy (<2 years). If the saphenous vein is absent or not suitable for bypass grafting, PTFE is a good alternative as bypass material.     

Infragenicular Bypass Graft for Limb Salvage Using Polytetrafluoroethylene and Distal Vein Cuff as the First Alternative in Patients Without Ipsilateral Greater Saphenous Vein

The objectives of this study were to evaluate the results of polytetrafluoroethylene infragenicular bypass grafts with a distal interposition vein cuff in patients with critical limb ischemia in the absence of ipsilateral greater saphenous vein. From January 1997 to June 2002, 58 consecutive below-knee bypass grafts with PTFE and distal interposition vein cuff were performed in 57 patients with a median age of 70.8 years. The distal anastomosis was located at the infragenicular popliteal artery in 18 cases and at tibial vessels in 40. Primary patency, secondary patency, and limb salvage were analyzed using the Kaplan-Meier method. During a median follow-up of 14.4 months (range, 1-50) 26 cases of graft occlusion and 19 major amputations were registered. The primary and secondary patency rates at 12, 24, and 36 months were 57%, 54%, and 47% and 61%, 58%, and 50%, respectively. Limb salvage rates reached 69%, 69%, and 59% at 12, 24, and 36 months. When below-knee revasculanzation is required in patients with limb-threatening ischemia, in the absence ipsilateral greater saphenous vein, PTFE grafts with a distal vein cuff are a reasonable substitute with acceptable long-term patency and limb salvage rates.     

Distal venous patch improves results in PFTE bypasses to tibial arteries

In recent years, the management of limb-threatening ischemia has involved the use of distal bypasses to vessels beyond the popliteal trifurcation. Excellent patency rates and limb salvage data are achieved through the use of autologous long saphenous vein. However, an increasing number of patients in need of tibial bypass do not have adequate saphenous vein due to previous procedures, thrombophlebitis, or inadequate vein. In such cases alternative conduits have been proposed including lesser saphenous vein, arm vein, composite veins, composite vein with polytetrafluoroethylene (PTFE), and PTFE with or without a distal arteriovenous fistula. Unfortunately these alternative conduits have not resulted in equivalent results when used for distal bypass to tibial arteries. Several authors have reported upon the use of venous tissue at the distal anastomosis in the form of cuffs, collars, and boots to improve the results of prosthetic grafts in this challenging patient population. These techniques have been proposed as an option for revascularization in patients without adequate saphenous vein in an attempt to obtain limb salvage. The purpose of this review is to examine some of those techniques and focus on distal vein patch configuration with its perceived advantages and drawbacks.     

Aggressive venous neointimal hyperplasia in a pig model of arteriovenous graft stenosis

BACKGROUND: Vascular access dysfunction is the most important cause of morbidity and hospitalization in the hemodialysis population in the United States at a cost of well over one billion dollars per annum. Venous neointimal hyperplasia characterized by stenosis and subsequent thrombosis, is the major cause of polytetrafluoroethylene (PTFE) dialysis graft failure. Despite the magnitude of the problem, there are currently no effective therapies for the prevention or treatment of venous neointimal hyperplasia in PTFE dialysis grafts. We believe that this is partly due to the lack of a validated large animal model of arteriovenous stenosis that could be used to test out novel interventions. METHODS: Seven-centimeter PTFE loop grafts were placed between the femoral artery and vein of domestic pigs. The grafts were removed at 2, 4, 7, 14 and 28 days after surgery and subjected to a detailed histological and immunohistochemical examination. RESULTS: Significant neointimal hyperplasia and venous stenosis developed by 28 days at the graft-vein anastomosis. There was minimal neointimal hyperplasia at the graft-artery anastomosis. Venous neointimal hyperplasia (VNH) was characterized by (a) the presence of smooth muscle cells/myofibroblasts; (b) angiogenesis within both the neointima and adventitia; and (c) the presence of an active macrophage cell layer lining the PTFE graft material. These results are very similar to the human lesion previously described by us in dialysis patients. CONCLUSIONS: We have developed and validated a pig model of venous neointimal hyperplasia that is very similar to the human lesion. We believe that this is an ideal model in which to test out novel interventions for the prevention and treatment of clinical hemodialysis vascular access dysfunction.     

The stenosed Brescia-Cimino fistula: operation or intervention?

INTRODUCTION: Stenosis of the vein close to the arteriovenous anastomosis is the most frequent cause for late failure of Brescia-Cimino fistulae (BCF). Although since decades proximal re-anastomosis has been regarded as the surgical standard treatment, success rates can hardly be deducted from the literature. Considering the increasing activities of interventional radiologists surgical position finding seems necessary. METHODS: Over three years 30 anastomotic BCF stenoses were treated in 28 patients. In 15 patients the stenosis had caused fistula thrombosis. In all cases the fistula vein was re-anastomosed to the proximal radial artery. All patients could be followed up (average 12 months). Each fistula functioning after 24 hours was classified as procedural success. For calculation of patency rates (life table analysis), however, usability of the needling segment of the access was assessed. RESULTS: Procedural success rate was 100%. One fistula thrombosed on the second postoperative day after a successful dialysis session due to an overlooked proximal stenosis of its feeding radial artery. In five fistulae stenoses developed after 4 to 13 months. In only one fistula this was a true re-stenosis of the newly created anastomosis (0.03 per patient-year). Two of the stenoses occurred in the needling segment of the access vein and within its central venous outflow, respectively. Overall re-intervention rate was 0.3 per patient-year, and primary (secondary) patency was 80% (95%) at one year and 67% (87%) at two years. CONCLUSION: In BCF proximal re-anastomosis is a simple and effective therapeutic option for anastomotic venous stenosis. Re-intervention rates are low and procedural success rates as well as primary and secondary patency rates at least equal those of interventional radiology.     

Clinical and biological relevance of vein cuff anastomosis

Since a significant number of patients do not have suitable autologous saphenous vein for femorodistal bypass, the search for alternative graft material continues. The most commonly used prosthetic material is Polytetrafluoroethylene, however because of the poor patency of these grafts in the below knee position, a variety of techniques have been tried to improve their patency. A series of studies utilizing venous cuffs at the distal anastomosis have showed improved patency of PTFE grafts. We have reviewed the biological basis for graft failure and the literature for possible mechanical explanations.     

The consequences of a failed femoropopliteal bypass grafting: comparison of saphenous vein and PTFE grafts

OBJECTIVES: Although there are numerous reports comparing saphenous vein (SV) and polytetrafluoroethylene (PTFE) with respect to the patency rates for femoropopliteal bypass grafts, the clinical consequences of failed grafts are not as well described. This study compares the outcomes of failed SV and PTFE grafts with a specific emphasis on the degree of acute limb ischemia caused by graft occlusion. METHODS: Over a 6-year period, 718 infrainguinal revascularization procedures were performed, of which 189 were femoropopliteal bypass grafts (SV, 108; PTFE, 81). Society for Vascular Surgery/International Society for Cardiovascular Surgery (SVS/ISCVS) standardized runoff scores were calculated from preoperative arteriograms. Clinical categories of acute limb ischemia resulting from graft occlusion were graded according to SVS/ISCVS standards (I, viable; II, threatened; III, irreversible). Primary graft patency and limb salvage rates at 48 months were calculated according to the Kaplan-Meier method. RESULTS: Patients were well matched for age, sex, and comorbidities. Chronic critical ischemia was the operative indication in most cases (SV, 82%; PTFE, 80%; P =.85). Runoff scores and preoperative ankle-brachial index measurements were similar for the two groups (SV, 6.0 +/- 2.5 [SD] and 0.51 +/- 0.29; PTFE, 5.3 +/- 2.8 and 0.45 +/- 0.20; P =.06 and P =.12). The distal anastomosis was made below the knee in 60% of SV grafts and 16% of PTFE grafts (P <.001). Grade II ischemia was more likely to occur after occlusion of PTFE grafts (78%) than after occlusion of SV grafts (21%; P =.001). Emergency revascularization after graft occlusion was required for 28% of PTFE failures but only 3% of SV graft failures (P <.001). Primary graft patency at 48 months was 58% for SV grafts and 32% for PTFE grafts (P =.008). Limb salvage was achieved in 81% of SV grafts but only 56% of PTFE grafts (P =.019). CONCLUSIONS: Patients undergoing femoropopliteal bypass grafting with PTFE are at greater risk of ischemic complications from graft occlusion and more frequently require emergency limb revascularization as a result of graft occlusion than patients receiving SV grafts. Graft patency and limb salvage are superior with SV in comparison with PTFE in patients undergoing femoropopliteal bypass grafting.     

Transluminal angioplasty of venous stenoses in polytetrafluoroethylene vascular access grafts

Since 1984, percutaneous transluminal angioplasty (PTA) utilizing high pressure balloon catheters has been used as an initial approach to restore patency of PTFE (polytetrafluoroethylene, GORE-TEX) hemodialysis vascular access grafts. Seventeen stenotic lesions detected by fistulogram underwent elective PTA. Twelve of these lesions were detected after thrombectomy and five were detected because of increased venous pressures during dialysis. Fourteen attempts at PTA were completely successful in restoring functional patency to the vascular graft. Three attempts were unsuccessful; two of these three grafts were subsequently repaired surgically. Venous stenoses that extended far greater than 6 cm were not considered for PTA. We conclude that PTA is a technique of promise in the non-surgical salvage of failing PTFE grafts. PTA can prolong the useful life of PTFE vascular access grafts and can be performed on an outpatient basis, eliminating the hospitalization that is usually required for surgical revision.     

Cutting balloon angioplasty for resistant venous anastomotic stenoses

Conventional angioplasty of stenoses at the venous anastomosis has been demonstrated to be an important endovascular adjunct to mechanical thrombectomy of clotted arteriovenous dialysis grafts. In some cases, however, severe venous anastomosis stenosis is resistant to angioplasty. Cutting balloon angioplasty may have an advantageous role in these difficult situations in order to avoid surgical revision. In this series of 350 patients receiving percutaneous, endovascular declotting procedures, 9 patients had high-grade venous anastomotic stenoses (opening less than 2 mm) that could not be remedied with either conventional or high-pressure noncompliant peripheral angioplasty balloons. These nine patients had the lesions opened with the use of 4 mm x 10 mm cutting balloons and placement of self-expanding nitinol stents at the venous anastomosis during the same angiography procedure. Patients were followed for patency and functionality of the graft. In all cases, immediate technical success occurred. Among these patients, the vessels have remained patent for as long as 20 months of follow-up and grafts have remained functional. Cutting balloon angioplasty may have a potential therapeutic role in resistant venous anastomotic stenoses.     

Axillary to saphenous vein bypass for treatment of central venous obstruction in patients receiving dialysis

OBJECTIVE: Venous hypertension due to subclavian or innominate vein stenosis coexisting with a functioning arteriovenous access in the ipsilateral arm is a complex problem in patients undergoing hemodialysis. Therapeutic solutions must optimally relieve symptoms, permit use of the angioaccess, and carry minimal surgical risk. The purpose of this study was to evaluate a simple surgical option, bypassing central venous obstruction to the great saphenous vein. METHODS: Eight patients undergoing hemodialysis with severe symptoms and signs of venous hypertension due to subclavian or innominate vein obstruction and ipsilateral arteriovenous fistula or graft underwent axillosaphenous bypass via a subcutaneous 8-mm polytetrafluoroethylene bridge graft. RESULTS: No intraoperative or immediate postoperative morbidity was observed. Early and 6-month patency rates were 100% and 87.5%, respectively. All patients reported improvement of symptoms, and the angioaccess was usable in all cases. Average follow-up was 21.5 months. One patient had a relapse at 5 months, which necessitated revision of the graft-saphenous vein anastomosis. CONCLUSION: Bypassing a central vein occlusion to the saphenous vein relieves symptoms of venous hypertension and prolongs use of the hemodialysis angioaccess.     

Proximal venous outflow obstruction in patients with upper extremity arteriovenous dialysis access

To evaluate the impact of central venous obstruction on upper extremity hemodialysis access failure, we retrospectively analyzed our recent experience in managing this problem. We reviewed 158 upper extremity hemodialysis access procedures performed in 122 patients during a 1-year period. Fourteen (11.5%) patients had central vein obstruction as the cause of severe arm swelling, graft thrombosis, or graft malfunction. All 14 patients had had bilateral temporary subclavian vein dialysis catheters and failed upper extremity arteriovenous access. Seventeen lesions were treated in 14 patients including eight subclavian vein occlusions, six subclavian vein stenoses, two internal jugular vein stenoses, and one superior vena cava stenosis. Twenty-one procedures were performed including 17 percutaneous transluminal balloon angioplasties (PTAs) with stent placement in 13, two axillary to innominate vein bypasses, and two axillary to internal jugular vein bypasses. All patients had resolution of symptoms. Thirteen (76%) PTAs were initially successful but in four (24%) cases it was impossible to recanalize the vein. Eight (47%) PTAs provided functional hemodialysis access for 2 to 9 months, two (12%) restenosed at 3 and 10 months and were successfully redilated, two occluded at 2 and 4 months and were unable to be recanalized, and one failed immediately after a successful PTA. Four PTA failures were followed by venous bypass, which remained patent and provided functional access 7 to 13 months after surgery. Of nine stenotic venous lesions six (67%) were successfully dilated without restenosis, whereas of eight occluded veins only two (25%) were successfully treated without recurrence. Temporary central hemodialysis catheters produce a significant number of symptomatic central vein obstructions in patients with upper extremity arteriovenous access. PTA with stenting and venous bypass provides early success in most patients. Transcatheter therapy is less successful in treating complete venous occlusions when compared with stenotic lesions. All effort should focus on preventing this complication by avoiding the use of temporary subclavian vein hemodialysis catheters.     

Regular ultrasonographic screening significantly prolongs patency of PTFE grafts

BACKGROUND: Polytetrafluoroethylene (PTFE) dialysis grafts have considerably shorter patency than native arteriovenous fistulas, despite the use of a complex of screening monitoring methods (venous pressure, access flow). PTFE grafts are used often in subjects with depleted subcutaneous veins after previous abandoned accesses, so keeping the access patent is crucial. We hypothesized that regular duplex Doppler ultrasound screening for access stenoses, together with their sooner treatment, would prolong PTFE graft patency. METHODS: We performed a randomized, prospective study of PTFE grafts' cumulative patency in 192 subjects. In group 1, regular ultrasound examinations performed every 3 months was added to traditional screening (i.e., regular access examination at hemodialysis unit, monitoring of venous pressure and access flow). Group 2 was screened only traditionally (without ultrasound). Interventions of suspected stenoses were indicated by nephrologists, vascular surgeon, and, in group 1, also by ultrasonography. Classic ultrasound criteria for significant stenosis were used, even if the access flow had not been decreased. The mean follow-up lasted 392 +/- 430 days. RESULTS: Groups were similar with respect to age, gender, diabetes status, and number of previous abandoned accesses. Group 1 had significantly longer access patency (P < 0.001). Number of interventions per graft was 2.1 +/- 1.8 and 1.3 +/- 1.0 in group 1 and group 2. CONCLUSIONS: Regular screening duplex Doppler ultrasonography results in significantly longer PTFE graft patency due to early detection of access stenosis and, thus, more frequent elective interventions of access stenoses.     

Vein cuff interposition prevents juxta-anastomotic neointimal hyperplasia.

This study sought to minimize juxta-anastomotic neointimal hyperplasia (JNIH) following the use of polytetrafluorethylene (PTFE) conduits. PTFE anastomoses to canine carotid arteries (noncuff grafts) were compared with grafts with vein cuffs interposed proximally and distally between the graft and native artery. This technique has been suggested clinically for below-knee PTFE femoropopliteal reconstruction. Twelve dogs received aspirin for 1 week before operation, which was continued after each animal received bilateral cuff and noncuff 4-mm PTFE grafts. At sacrifice, after 3-12 weeks, graft patency was assessed and luminal diameters measured with ophthalmic calipers at three sites along the anastomoses and 1 mm proximal or distal to graft toe (A' diameter). Specimens were perfusion fixed at arterial pressure for gross and histologic study; selected arteries were additionally fixed with 4% buffered glutaraldehyde, stored at 4 C, and examined immunochemically using antimyosin antibody immunopurified for smooth muscle. Overall patency of noncuff grafts in 11 long-term surviving dogs was 4 of 11; patency of the cuff grafts was 7 of 11. Regardless of graft thrombosis, antibody positive cellular proliferation occurred mainly at noncuffed PTFE anastomoses. Luminal encroachment was predominantly due to subintimal proliferation of cells highly reactive to smooth muscle derived antibody. JNIH was most prominent 1 mm distal to the graft toe (A' distal diameter). Average A' for noncuff grafts was 1.82 mm +/- 0.97 SEM; average A' diameter for cuff grafts was 3.41 mm +/- 0.74 SEM (p less than 0.001). Vein cuff inhibition of proliferation of smooth muscle or cells derived from smooth muscle possibly relates to wider distribution of kinetic energy (less compliance mismatch) or to interposition of venous endothelium.     

Improving longevity of prosthetic dialysis grafts in patients with disadvantaged venous outflow

OBJECTIVE: Angioaccess for hemodialysis in an extremity with disadvantaged venous outflow has reduced long-term patency. We hypothesized that arteriovenous bridge graft patency could be improved in patients with disadvantaged venous outflow by preoperative venous duplex mapping. METHODS: The charts of 114 patients who underwent 115 prosthetic arteriovenous bridge grafts were reviewed. Disadvantaged venous outflow was defined on the basis of any combination of prior arteriovenous bridge graft, multiple venipunctures, and clinical examination. Patients were grouped according to the presence or absence of disadvantaged venous outflow. Three groups were analyzed: those with normal venous outflow who had an initial arteriovenous bridge graft (NML), those with disadvantaged venous outflow who had only a clinical examination before redo arteriovenous bridge graft (REDO/DVO), and those with disadvantaged venous outflow who underwent preoperative duplex scanning venous evaluation (MAP/DVO). Life table primary and secondary 12-month patency rates were compared by means of log-rank analysis. RESULTS: Life table analysis yielded 6-month primary patency rates of 65.9% +/- 5.7%, 66.4% +/- 7.3%, and 43.8% +/- 10.9% for NML, MAP/DVO, and REDO/DVO, respectively. The secondary patency rates at 6 months for NML (91.9% +/- 3.4%) and MAP/DVO (91.1% +/- 4. 9%) were statistically equivalent, and both were significantly better than the patency for REDO/DVO (75.0% +/- 10.0%; P =.004 and P =.04, respectively). This trend persisted beyond 12 months. CONCLUSION: Preoperative evaluation of venous anatomy in patients with disadvantaged venous outflow results in an arteriovenous bridge graft patency comparable to that seen in patients undergoing initial arteriovenous bridge grafts. Vein mapping improves arteriovenous bridge graft durability in the patient with disadvantaged venous outflow by allowing the surgeon to select venous return that is in direct continuity with the central venous system.     

Surgical reconstruction of iliofemoral veins and the inferior vena cava for nonmalignant occlusive disease

PURPOSE: Venous reconstructions are rarely performed, and factors affecting long-term results of bypass grafts implanted in the venous system are not well defined. In this report we updated our experience. METHODS: The clinical data of all patients who underwent venous reconstruction for iliofemoral or inferior vena caval (IVC) occlusion due to nonmalignant disease between January 1985 and June 1999 were retrospectively reviewed. Patients were classified, and outcomes were compared according to the guidelines of the Joint Vascular Societies. RESULTS: Forty-two patients, 23 males and 19 females (mean age, 40 years; range, 16-81), underwent 44 venous reconstructions. Thirty-six patients had limb swelling or venous claudication, 38 had pain, and 14 had healed or active ulcers. The cause of obstruction was congenital in two and acquired in 40 (deep vein thrombosis, 25; trauma, 5; retroperitoneal fibrosis, 4; IVC occlusion devices, 4; others, 2). Eighteen patients underwent saphenous vein crossover grafts (Palma procedure), 17 had expanded polytetrafluoroethylene (ePTFE) grafts implanted (femorocaval, 8; iliocaval, 5; crossfemoral, 3; cavoatrial, 1), 6 patients had spiral vein grafts (5 iliac/femoral and 1 cavoatrial), and 1 underwent femoral vein patch angioplasty. Clinical follow-up averaged 3.5 years (median, 2.5), and graft follow-up with imaging studies averaged 2.6 years (median, 1.6). Seven patients were lost to follow-up. The secondary 3-year patency rate for all reconstructions was 62%. Palma procedures had a 4-year patency rate of 83%. The secondary patency rate of iliocaval and femorocaval ePTFE bypass grafts at 2 years was 54%. The secondary patency was lower in patients with an arteriovenous fistula (P =.023). All ePTFE grafts had a 45% patency rate at 2 years, not significantly different from saphenous vein grafts (83%, P =.16). Clinical scores improved with graft patency (median, 0.0 vs 1.5; P =.044). CONCLUSIONS: Venous reconstructions for iliofemoral or IVC obstruction offer 3-year patency rates of 62%. The Palma procedure with autologous saphenous vein had the best long-term patency, whereas long-term success with ePTFE was moderate. The use of an arteriovenous fistula to improve graft patency remains controversial.     

The non-reversed vein femoro-distal bypass graft: a modification of the standard in situ technique

The results of 85 in situ vein femoro-distal bypass grafts using a modified technique where the vein was completely mobilised but left "non-reversed" have been reviewed with particular regard to risk factors and complications. The distal anastomosis was to the infrageniculate popliteal artery in 55% and to the tibioperoneal trunk or a single calf vessel in the rest. Arteriographic run-off was by a single vessel in 42%. The primary failure rate at 1 month was 20% and the secondary failure rate 9%; the majority of early failures being due to missed technical errors despite the use of a pulse volume recorder. The cumulative secondary patency rate at 1 and 2 years was 77% and 72%; limb salvage 85% and 77%; and patient survival 89% and 83% respectively. The only significant risk factors were the level of the distal anastomosis and the run-off (P = 0.002 and 0.03 respectively). Complete mobilisation of the vein allows a tension free proximal anastomosis to the common femoral artery and avoids the risk of arteriovenous fistulae. A high vein utilisation rate of 93% was achieved by using a small 2.5 mm Hall valvulotome. Although there was a trend towards lower patency rates in veins with a minimum diameter less than 4 mm the results are still superior to PTFE. Compared to reversed vein the in situ technique has a better utilisation rate and the long-term patency rates are at least as good if not better. Improved methods of haemodynamic assessment during reconstruction to reduce technical errors may be the key to better early patency rates.