Lower Limb Bypass Graft Research Articles

Managing incisional wounds with Prevena VAC therapy in lower-extremity vascular surgery: A comparative study.

Vascular surgical site infections have been reported with an overall incidence of 5-10% for patients undergoing arterial interventions and as high as 10-20% for lower-limb bypass grafting procedures. Given that vascular surgery patients are known to be at a higher risk of postoperative wound infections and other complications, our objective was to evaluate a potential method to reduce such complications. This study compares the rate of wound healing complications between incisional negative pressure wound therapy (NPWT) and conventional dressings in vascular surgery patients with infra-inguinal incisions. The primary endpoint is complete closure of the wound at the 2-week follow-up appointment. Secondary endpoints include frequency infections requiring antibiotics, need for wound revision, and wound dehiscence. A prospective cohort study with retrospective control group was performed following infra-inguinal vascular surgeries for peripheral arterial disease at the Mount Carmel Health System. The patients included in this study were those who underwent a lower-extremity vascular procedure with primary closure of an incision distal to the groin between January 2014 and July 2018. Patients that had received an infra-inguinal incision with primary closure were included. Patients in the experimental group who had a Prevena Wound VAC were compared with a retrospectively obtained control arm treated with conventional dressings. Data regarding wound healing and complications, specifically infections and wound dehiscence, were obtained. A total of 201 patients were recruited in our study: 64 in the Prevena group and 137 in the control group. There was a significant reduction in the number of open wounds in the Prevena group compared to the control group at the 2-week follow-up (10.9% Prevena vs 33.6% control; p = .0005). When evaluated in aggregate, there was a statistically significant reduction in the number of patients who succumbed to any complication in the Prevena arm compared with traditional dressings (13 (20.3%) Prevena vs 72 (52.6%) control; p < .0001). The results of our study suggest there should be a significant consideration for the use of NPWT as a prophylactic measure to reduce the risk of wound complications of primarily closed infra-inguinal incisions in vascular surgery patients following common vascular procedures. Its use is particularly effective for patients at enhanced risk of infection, especially those with poor vascularization from BMI, smoking, and diabetes. This leads to decreased trends in antibiotic use, ED visits, readmissions, and surgical revisions, which translates to decreased utilization of hospital resources and economic burden.

A review of methodologies evaluating in-vivo superficial vein properties: focus on compliance and reactivity.

The saphenous vein (SV) is a hindlimb superficial vein which has aroused a considerable interest because of its implication in chronic venous disease and its use in coronary artery or lower limb bypass grafts. The morphology and patency of the SV are commonly assessed for diagnosis and management, but the dynamic properties of the vein (compliance, elasticity and reactivity, less widely studied) are also fundamental issues. The subject of this review is neither to review the pathologies, nor the treatments or surgical procedures. The goal is to gather together all existing types of investigation on the superficial vein and to focus on the dynamic venous properties in vivo. The data collected indicate that plethysmography (PG) and ultrasound (US) are extensively used to evaluate SV patency, reflux and morphology. Their use to evaluate superficial vein compliance is less widespread but highly necessary. The protocols used via venous occlusion are described and the various parameters used to accurately measure compliance and distensibility versus elasticity are presented and discussed. The advantage of US diameter measurement is shown, including additional pulsatile compliance evaluation. The overview of venous reactivity greatly differs, being poorly studied in vivo, mainly by optical methods in humans or US echotracking in animals. Existing methodologies are potent but could be certainly developed and improved further for better characterization of the SV in human and for investigations of new devices, surgical techniques and pharmacological treatment in preclinical animal studies.

COVID-19 Infection and Early Outcome of Acute Peripheral Vascular Events A propensity Score Matching Analysis

AbstractBackground and aim: The present study aimed to compare the short term outcome of thromboembolic events affecting the peripheral vascular system in patients with concomitant COVID-19 infection and patients without this infection. Patients and methods: The study included 177 covid-19 patients with peripheral vascular events. They comprised 62 patients with acute lower limb ischemia, 69 patients with lower limb DVT, 21 patients with thrombosed vascular access and 25 patients with occluded lower limb bypass graft. For comparison, we selected another 177 patients with peripheral vascular events without covid-19 infection. Patients were selected using a propensity score matching with 1:1 ratio. Patients were followed for 30 days after admission. Results: Comparison between acute lower limb ischemia with and without covid-19 revealed that covid-19 patients had higher amputation rate (25.8 % versus 12.9 %, p=0.069) without statistical significance. However, multivariate regression analysis identified covid-19 infection as a significant predictor of limb amputation [OR (95% CI: 3.31 (1.15-9.6), p=0.027]. In DVT patients, covid-19 patients had significantly lower clinical improvement (75.4 % versus 91.3 %, p=0.012). In patients with vascular access thrombosis, covid-19 patients had lower secondary patency rates (61.9 % versus 71.4 %, p=0.52) without statistical significance. In patients with occluded lower limb bypass graft, covid-19 patients had markedly lower secondary patency rates despite falling short of statistical significance (68.0 % versus 88.0 %, p=0.088).Conclusions: Covid-19 infection is related to worse outcome in many patients with peripheral vascular events particularly those with acute lower limb ischemia and DVT.

Efficacy of Balloon Angioplasty for Infrainguinal Vein Graft Stenosis

Vein graft stenosis is a critical complication of lower-limb bypass surgery. For vein graft stenosis, balloon angioplasty has been performed instead of surgical revision in recent years. We therefore investigated the effectiveness of the balloon angioplasty for vein graft stenosis. We conducted a retrospective analysis of prospectively collected data for 115 vein graft stenoses performed via balloon angioplasty from August 2011 to January 2018. The rate of freedom from reintervention after balloon angioplasty was 54.3%, 44.4%, and 38.0% at 1, 2, and 3years, respectively. The rate of freedom from graft occlusion after balloon angioplasty was 79.9%, 71.9%, and 61.3% at 1, 2, and 3years, respectively. Predictors of freedom from graft occlusion after balloon angioplasty by a multivariate analysis were a single treated lesion (hazard ratio [HR]: 0.38; 95% confidence interval [CI]: 0.17-0.85; P=0.0189), balloon angioplasty within 90days after bypass surgery (HR: 3.59; 95% CI: 1.56-8.07; P=0.0033), and using a cutting balloon (HR: 0.42; 95% CI: 0.17-0.97; P=0.0426). The freedom from graft occlusion rate after balloon angioplasty remained relatively high. Furthermore, better results can be expected in single treated lesions and cases of balloon angioplasty occurring 90days after bypass surgery or in which a cutting balloon was used. Balloon angioplasty for lower-limb bypass graft stenosis was shown to be a useful treatment.

A systematic review of isolated radial artery harvesting as a conduit for lower limb bypass grafting.

Whilst autologous vein conduits have been heralded as the first-line approach for patients undergoing lower limb bypass grafting procedures, patients with peripheral arterial occlusive disease may have exhausted venous options given prior use for cardiac surgery, varicose vein surgery, or lower limb revascularization. Hence, the use of a radial artery graft may serve as a viable alternative. The systematic review was performed in accordance to the Preferred Reporting Items for Systematic Review and Meta-analysis guidelines. An electronic search was performed on the following databases: Medline (via PubMed); EMBASE; Cochrane library to search for relevant publications. A narrative analysis was conducted. Four publications were included in this review including two retrospective cohort studies, one case series, and one case report, with a total of 43 patients. The most common indication for lower limb bypass grafting was critical limb ischemia, and the radial artery was chosen as graft conduit, most commonly due to the absence of suitable arm or leg vein. There was one case of 30-day mortality and 11 reinterventions. Despite the encouraging results, the paucity of high-quality studies prevents the establishment of any firm conclusion. This warrants the need for appropriately conducted randomized controlled trials to compare the radial artery graft to autologous vein grafts and prosthetic grafts for lower limb bypass grafting.

Repeated Episodes of Remote Ischemic Preconditioning for the Prevention of Myocardial Injury in Vascular Surgery.

Remote ischemic preconditioning (RIPC) involves the phenomenon whereby transient episodes of limb ischemia induced by cuff inflation provide cardioprotection. The effectiveness of RIPC in vascular surgery is uncertain. This randomized, controlled trial was designed to investigate the potential of two episodes of RIPC to provide myocardial protection in patients undergoing vascular surgery. Patients undergoing an elective major vascular procedure (open abdominal aortic aneurysm (AAA) repair, endovascular aneurysm repair, and lower-limb bypass grafting) were randomized into RIPC group (n = 42) or control group (n = 43). Remote ischemic preconditioning consisted of three 5-minute cycles of upper limb cuff occlusion with 5-minutes of reperfusion between cycles, both 24 hours and immediately before surgery. Control patients received a similarly timed sham treatment. Cardiac high-sensitivity troponin T (hsTnT) concentration was measured in plasma at 6, 12, 24, and 48 hours post-surgery, and at 72, 96, and 120 hours in patients still in hospital. Perioperative clinical adverse events and readmissions within ∼12 months were recorded. Myocardial injury was demonstrated perioperatively in 43% of RIPC patients and 49% of controls, as defined by a significant hsTnT elevation. These incidences were statistically equivalent (odds ratio 0.79, 95% confidence interval 0.33-1.85, P = .58). The 48-hour area under the curve for hsTnT change from baseline also revealed no difference (RIPC vs control median: 5.3 vs 7.5 ng/L.h, P = .22). Each group had one type I and one type II myocardial infarction and no difference in complications or readmissions. This trial could not confirm that two episodes of RIPC reduce myocardial injury following vascular surgery. Along with other equivocal studies, it appears that RIPC does not induce a clear benefit in vascular surgery.

Cryoplasty for peripheral arterial disease

Percutaneous balloon angioplasty is an endovascular technique for restoring blood flow through an artery that has become narrowed or blocked by atherosclerosis. Narrowing of the artery following angioplasty (restenosis) is the major cause of long-term failure. Cryoplasty offers a different approach to improving long-term angioplasty results. It combines the dilation force of balloon angioplasty with cooling of the vessel wall. This systematic review evaluated cryoplasty in peripheral arterial disease and provides focus for further research in the field. This is an update of a review first published in 2007. To assess the efficacy of, and complications associated with, cryoplasty for maintaining patency in the iliac, femoropopliteal and crural arteries in the short and medium term. For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched October 2012) and CENTRAL (2012, Issue 10). Trial databases were searched for ongoing or unpublished studies. We also searched the reference lists of relevant articles. All randomised controlled trials in which participants with peripheral arterial disease (PAD) of the lower limbs, or lower limb bypass graft stenoses, were randomised to cryoplasty with or without another procedure versus a procedure without cryoplasty were considered. This included trials where all participants received angioplasty and the randomisation was for cryoplasty versus no cryoplasty and trials where cryoplasty was used as an adjunct to conventional treatment (for example stenting) against a control. Two review authors independently reviewed, assessed and selected trials, extracted data and assessed risk of bias. Seven trials (six primary cryoplasty and one adjunctive cryoplasty trial) with a combined total of 478 patients were included in this review. The trials reported patency and restenosis either by participant, lesion or vessel location. Follow-up ranged from 30 days to three years.Target lesion patency measured at various time points in two primary cryoplasty trials showed no statistically significant difference between the treatment groups. The adjunctive cryoplasty study showed that cryoplasty was associated with improved patency only at six months (OR 5.37, 95% CI 1.09 to 26.49, n = 90).Restenosis measured per patient (two primary cryoplasty trials) showed no statistically significant difference between the treatments. Restenosis measured by lesion (two primary cryoplasty trials) showed a statistically significant difference only within 24 hours of the procedure (OR 0.08, 95% CI 0.04 to 0.18, n = 192) favouring cryoplasty.Need for re-intervention was not significantly different in primary cryoplasty trial participants (per participant: OR 0.27, 95% CI 0.05 to 1.52, n = 241, I(2) = 89%; per lesion: OR 0.59, 95% CI 0.06 to 5.69, n = 307, I(2) = 94%). The adjunctive cryoplasty trial did not report on need for intervention.Immediate success of procedure (within 24 hours) was not significantly different in primary cryoplasty trial participants (per participant: OR 1.63, 95% CI 0.14 to 19.55, n = 340, I(2) = 95%; per lesion: OR 1.81, 95% CI 0.19 to 17.36, n = 397, I(2) = 90%). The adjunctive cryoplasty trial reported 100% success.Limb loss, deaths from all causes and the risk of complications immediately after treatment showed no statistically significant differences between the treatments. The benefit of cryoplasty over conventional angioplasty cannot be established as the number of randomised controlled trials is small and their quality is not sufficiently high. The technical success and primary patency rates seen in these trials are inconsistent and do not necessarily suggest a future role for cryoplasty in the treatment of PAD, but they cannot be reliably interpreted. Currently there are insufficient data to support the routine use of cryoplasty over conventional balloon angioplasty in the treatment of PAD.

Correction: Public reporting of surgeons’ performance

Incorrect name of organisation, and further clarification: In “Public reporting of surgeons’ performance” in the 6 May 2013 issue of the Journal (Med J Aust 2013; 198: 399-400), the organisation named as the Australian Vascular Society should have been given as the Australian and New Zealand Society for Vascular Surgery (ANZSVS). The administrator of the Australasian Vascular Audit, a project of the ANZSVS, has requested that it be noted that carotid endarterectomy is one of a number of procedures audited for outcomes. Other procedures audited are open and endovascular aortic surgery, lower-limb bypass graft surgery and arteriovenous fistulae formation for haemodialysis access (see Beiles CB, Bourke B, Thomson I. Results from the Australasian Vascular Surgical Audit: the inaugural year. ANZ J Surg 2012; 82: 105-111).

Arterial Duplex Imaging of Lower-Extremity Arteries and Interventions

The application of duplex ultrasound for the evaluation of patients with lower-limb arterial occlusive disease provides the clinician with detailed information on its location, extent, and severity. Duplex scanning from the visceral aortic segment to the tibial arteries allows the detection of aneurysms and occlusive disease with a classification of its severity, including the presence of critical limb ischemia. Testing should be performed in conjunction with limb pressure measurements to accurately categorize arterial hemodynamics and functional impairment. Interpretation of duplex-acquired velocity spectra recordings is fundamental to successful clinical evaluation, including the characteristic features of normal versus and abnormal lower-limb arterial flow and hemodynamic changes associated with stenosis both at the occlusive lesions and its impact on distal limb perfusion. Duplex testing is accurate both before and after intervention for the diagnosis of occlusion and stenosis severity allowing decisions regarding treatment (medical, open surgical repair, endovascular therapy) to be made. Scanning can provide an arterial map of occlusive or aneurysm lesions analogous to magnetic resonance or computed-tomography angiography. An important duplex ultrasound application is for the surveillance of lower-limb bypass grafts and peripheral angioplasty for the development of stenosis that is their common mode of failure. The detection of high-grade stenosis in an arterial repair allows for pre-emptive treatment before thrombosis and improves long-term patency.

Native chronic total occlusion recanalization after lower limb bypass graft occlusion: A series of nine cases

The aim of the study was to report the clinical utility of native chronic total occlusion (CTO) recanalization as an endovascular strategy in lower limb bypass graft occlusion. There is no consensus on the best approach for threatened limbs in patients with graft occlusion. The subjects were nine consecutive patients with limb-threatening ischemia after bypass graft occlusion. Native CTO recanalization was attempted endovascularly using conventional intraluminal and subintimal angioplasty techniques supported by stents. The mean age of the bypass grafts was 6.7 +/- 7.3 (range: 1-24) months and the mean number of previous lower limb bypass surgeries was 1.4 +/- 0.5 (range: 1-2). Native CTO recanalization was performed in the iliofemoral (n = 2), iliac (n = 2), superficial femoral (n = 3), popliteal (n = 1), and popliteal-tibial (n = 1) arteries. Technical success was achieved in 89% (8/9) of cases without complications or major adverse cardiovascular events. The ankle-brachial index and skin perfusion pressure of the foot significantly increased after revascularization, with marked improvement of clinical symptoms (Rutherford class: 4.5 +/- 1.1-->0.9 +/- 1.4, P < 0.001). Limb salvage was achieved in all successful recanalization cases during the mean follow-up time of 25 +/- 20 months (range: 9-60). In this preliminary study, endovascular recanalization of native CTO showed satisfactory outcomes in patients with bypass graft occlusion.

Low wall shear stress predicts subsequent development of wall hypertrophy in lower limb bypass grafts

Venous grafts commonly develop myointimal hyperplasia, which can lead to stenoses and, ultimately, with expression of adhesion molecules, lumenal occlusion. The aim of the present study was to investigate whether wall shear stress measured post-operatively would predict subsequent myointimal hypertrophy in lower limb venous bypass grafts. Magnetic resonance imaging and ultrasound were performed in a cohort of patients following lower limb venous bypass graft surgery for peripheral arterial disease at baseline (1-2 weeks) and at follow-up (9-12 months). Wall shear stress was determined at baseline using computational fluid dynamics techniques and intima-media thickness along the length of the graft was measured by ultrasound at baseline and follow up. Complete follow-up was possible in eight patients, in whom low wall shear stress at baseline predicted high intima-media thickness. The relationship between wall shear stress (WSS) and intima-media thickness (IMT) was curvilinear with IMT increasing sharply at lower levels of WSS (IMT >1.0 mm at <0.3 Pa). Low wall shear stress is associated with subsequent increase in myointimal thickness in lower limb venous bypass grafts. This is believed to be the first prospective study in humans to demonstrate the relationship between low wall shear stress and myointimal thickening and indicates a likely causative role for low wall shear stress in the development of myointimal hyperplasia.

Vascular Surgical Site Infection: Risk Factors and Preventive Measures

Surgical-site infection (SSI) after arterial intervention is the most common nosocomial vascular infection and an important cause of postoperative morbidity. Its prevention requires the vascular surgeon to be cognizant of its changing epidemiology, patient risk factors, and effective measures to reduce its incidence. The majority of vascular SSIs are caused by Gram-positive bacteria, and methicillin-resistant Staphylococcus aureus has emerged as the prevalent pathogen, now involved in more than one-third of cases. Nasal carriage of methicillin-sensitive or methicillin-resistant S. aureus strains, recent hospitalization, failed arterial reconstruction, and presence of a groin incision, are major risk factors for developing vascular SSI. Overall, the vascular SSI rate is higher than predicted by Center for Disease Control National Nosocomial Infections Surveillance risk category system, and ranges from 1% to 2% after open or endovascular aortic interventions to as high as 10% to 20% after lower-limb bypass grafting procedures. Use of preoperative measures to reduce S. aureus nasal and skin colonization in conjunction with appropriate, bactericidal antibiotic prophylaxis, meticulous wound closure, and postoperative care to optimize patient host defense regulation mechanisms (temperature, oxygenation, blood sugar) can minimize SSI occurrence.

Surveillance After Lower Extremity Arterial Bypass

The elements of a surveillance program after lower limb bypass grafting to enhance graft patency continue to evolve. Graft evaluation should include clinical assessment for new or changes in limb ischemia symptoms, measurement of ankle or toe systolic pressure, or both, and duplex ultrasound imaging of the bypass graft, which in the early postoperative period is predictive of the subsequent need for bypass graft revision. The natural history of moderate graft stenosis is known, and these lesions can be safely monitored using serial testing to identify progression. The testing frequency should be individualized to the patient, type of arterial bypass, and duplex scan findings. Graft surveillance should focus on the identification and repair of critical stenosis (peak systolic velocity exceeding 300 cm/s, and peak systolic velocity ratio across the stenosis exceeding 3.5) correlating with more than 70% diameter-reducing stenosis. A graft surveillance program should result in a graft failure rate of less than 3% per year.

Assisted Patency with Primary Stent Placement in Distal Anastomotic Stenoses of Lower Limb Bypass Grafts

To evaluate the feasibility and effectiveness of primary stent placement for treating distal anastomotic infragenicular bypass stenoses in terms of technical success and middle-term (2-year) patency rates. Twenty-one patients underwent primary stent placement for the treatment of distal anastomotic stenoses after infragenicular bypasses. Patients underwent clinical and color flow and duplex Doppler ultrasonographic (US) examinations 1, 3, 6, and 12 months after the endovascular procedure and every year thereafter if no complications occurred. Angiography was performed in patients with positive findings at the clinical and US examinations to evaluate the need for repeat endovascular and/or surgical treatment. The mean follow-up was 18.3 months (range, 2-30 months). Twenty-two clinically significant (>50%) distal anastomotic stenoses were detected in 22 infragenicular grafts created in the 21 patients. The median time between endovascular treatment and surgery was 7.5 months (range, 3-18 months). The mean stenosis length was 1.4 cm (range, 0.8-2.4 cm). Twenty-four stents were implanted, two of which were used to treat restenosis immediately below the previously implanted stent. The technical success rate was 100%. No complications occurred during any of the treatments, and no periprocedural major events or complications were registered. At follow-up, the cumulative primary, primary assisted, and secondary patency rates for the treated graft stenoses were 95%, 95%, and 100%, respectively, at 6 months; 71%, 81%, and 86% at 1 year; and 71%, 76%, and 81% at 2 years. The limb salvage rate was 88%. Although this study was limited to a small number of patients, stent placement seems to be a feasible and effective tool in the endovascular treatment of distal anastomotic infragenicular bypass graft stenoses.

Measurement of anastomosis geometry in lower extremity bypass grafts with 3-D ultrasound imaging

The attachment sites of lower extremity bypass grafts are known to exhibit a wide range of geometries. Factors that determine the geometry of a given anastomosis include graft material, graft site, native vessel size, graft size and individual patient anatomy. Therefore, it is difficult to specify a standard anastomosis geometry before surgery and difficult to predict the effect of the geometry on long-term graft patency. We have used 3-D ultrasound imaging to study 46 proximal anastomoses of lower limb bypass grafts. We have developed methods to characterize the 3-D geometry of the anastomosis in terms of component sizes and angles. These detailed geometric measurements describe a range of anastomosis geometries and establish standardized parameters across cases that can be used to relate anastomosis geometry to outcome. (E-mail: leotta@u.washington.edu)

Surveillance of lower extremity bypass grafts

Duplex ultrasound graft surveillance can prevent graft failure by accurate detection and then repair of lesions prior to graft thrombosis occurring. Lower limb bypass grafts are prone to develop intrinsic lesions after implantation into the arterial circulation, despite careful operative technique. Duplex surveillance after infrainguinal vein bypass grafting should begin in the operating room because 15% of grafts will have lesions identified—conduit stenosis/fibrosis, inadequate valve lysis, anastomotic stenosis, and formation of platelet thrombus. The correction of graft lesions reduces the incidence of early thrombosis and the need for secondary interventions for residual stenosis. Vein bypasses with normal intraoperative duplex studies demonstrate <1% incidence of graft thrombosis within the first 3 months of implantation; by comparison, residual duplex abnormalities result in thrombosis or revision in 15–25% of grafts. Duplex testing should be repeated prior to discharge, as the identification of a low-flow (<40 cm/s) graft may indicated need for anticoagulation. Testing at 4–6 weeks is recommended if pre-discharge scanning was not complete or a residual stenosis (PSV < 300 cm/sec, Vr < 3.5) identified. Repair of all stenoses with a PSV > 300 cm/s and Vr > 3.5 is recommended, especially if the lesion has progressed (increasing PSV) on serial scans, or a low (PSV < 40 cm/s) graft flow velocity is detected. The combination of high- and low-velocity criteria identifies bypasses at the highest risk for thrombosis. These threshold criteria identified all grafts at risk for thrombosis, and <5% of lesions with high-velocity criteria regressed. Most graft stenoses are asymptomatic, and thus appropriate criteria of the “severe” stenosis should be applied when recommending intervention by either balloon angioplasty or open surgical repair. The incidence of vein graft stenosis decreases (annual incidence of 2–4%) with time, but because of atherosclerotic disease progression in native arteries (5–10% incidence) and aneurysm formation in the vein conduit, life-long surveillance is recommended. Duplex surveillance is cost effective and improves long-term graft patency and limb salvage rates by approximately 15–20%.

Thrombolysis of occluded synthetic bypass grafts in the lower limb: technical success and 1-year follow-up in 32 patients.

To evaluate prospectively the technical success and clinical outcome of thrombolysis for acute occlusion of synthetic arterial bypass grafts in the lower limb. Thirty-two consecutive patients (27 men; median age 65 years, range 41-80) with occluded polytetrafluoroethylene bypass grafts were treated with direct-catheter thrombolysis (100,000-IU bolus of urokinase with 100,000-IU/h infusion) followed by ancillary interventions to treat underlying stenosis whenever necessary. All patients received oral anticoagulation to maintain the international normalized ratio at 3.0 to 4.0. Clinical follow-up and duplex ultrasound examinations were performed at 3-month intervals up to 1 year. Thrombolysis was technically successful in 27 (84%) patients; 3 of the 5 failed patients had amputations. Mean duration of urokinase therapy was 36+/-14 hours. In 18 patients, underlying stenoses (11 distal anastomosis, 5 proximal anastomosis, and 3 inflow) were treated, 15 by an endovascular procedure and 3 surgically. Four major complications occurred: groin hematoma, sepsis, transient renal dysfunction, and a hemorrhage at the proximal anastomosis after urokinase treatment. At 1 year, 21 bypass grafts had reoccluded (20% patency rate on intention-to-treat basis); 3 reocclusions resulted in amputation (overall 19% amputation rate). Thrombolysis in the setting of acute lower limb bypass graft occlusion is associated with good initial technical success rates and satisfactory clinical results. However, the re-occlusion rate within 1 year is high.

Utility of duplex surveillance following iliac artery angioplasty and primary stenting.

To evaluate the clinical outcome and patency rates after iliac artery angioplasty and primary stenting using a noninvasive surveillance protocol that includes duplex ultrasonography. Sixty-seven patients (64 men; mean age 61 +/- 9 years, range 45-83) underwent stenting of 84 iliac systems for claudication (63%), rest pain (9%), tissue loss (20%), or failing lower limb bypass graft (8%). The surveillance algorithm included aortoiliac duplex scanning within 1 month and serial limb pressure measurements and femoral artery waveform analyses during follow-up. Iliac systems with a peak systolic velocity >300 cm/s and velocity ratio >2.0 by duplex and/or symptomatic or hemodynamic deterioration were considered failing and an indication for angiography. During intermediate-term follow-up ranging to 36 months (mean 12), life table primary, assisted primary, and secondary patency rates for the treated iliac systems were 78%, 90%, and 98%, respectively, at 18 months. Assisted primary iliac system patency at 18 months was significantly worse in the 20 (24%) limbs having an outflow bypass done with or prior to iliac stenting (83% versus 100% without bypass, p = 0.01). Indirect clinical indicators found 17 (20%) suspected failing iliac systems, in which duplex imaging correctly identified 5 of 6 recurrent iliac stenoses and facilitated secondary endovascular intervention. Three (4%) stent occlusions occurred in the treated iliac systems despite surveillance. Duplex surveillance after iliac stenting localizes failing inflow segments, optimizes assisted patency of the treated iliac system, and possesses greatest utility in patients with multilevel occlusive disease and outflow reconstructions.

Pulsed Transthrombotic Fibrinolysis: Technique and Results in the Management of Occluded Lower Limb Bypass Grafts

Between March 1987 and March 1993 we used pulsed transthrombotic fibrinolysis to treat 58 symptomatic thrombotic occlusions of lower limb bypass grafts in 45 patients. There were 17 suprainguinal grafts and 28 infrainguinal grafts. Treatment consisted of pulsed infusion of fibrinolytic agents into the thrombus followed by continuous infusion using an electric pump. Minor percutaneous or surgical procedures were often associated. The mean delay to treatment was 7 days. The mean duration of treatment was 150 +/- 66 minutes. Immediate patency was achieved in 88% of cases with no significant difference between suprainguinal and infrainguinal grafts. The clinical success rate was 55%. Actuarial patency at 1 year was 54% +/- 11% for suprainguinal grafts and 26% +/- 7% for infrainguinal grafts. The probability of patency was much lower in patients whose grafts had been implanted within 3 months before occlusion and in patients in whom an adjuvant procedure had not been performed. This study demonstrates that, in cases not requiring immediate surgery, pulsed transthrombotic fibrinolysis can achieve durable patency by treating both the bypass and distal arterial network. This technique allows identification of lesions causing thrombosis and adaptation of treatment specifically to these lesions.

Results of a prospective, randomized trial of surgery versus thrombolysis for occluded lower extremity bypass grafts

The purpose of this study was to prospectively evaluate the treatment of patients with occluded lower extremity bypass grafts, comparing surgical revascularization with catheter-directed thrombolysis. One hundred twenty-four patients (68% male and 32% female) with lower limb bypass graft occlusion (46 autogenous and 78 prosthetic) were prospectively randomized to surgery (n = 46) or intra-arterial catheter-directed thrombolysis (n = 78) with recombinant tissue plasminogen activator (rt-PA) 0.1 mg/kg/h modified to 0.05 mg/kg/h for up to 12 hours, or urokinase (UK) 250,000 U bolus followed by 4,000 U/min for 4 hours, then 2,000 U/min for up to 36 hours. A composite clinical outcome including death, amputation, ongoing/recurrent ischemia, and major morbidity was analyzed on an intent-to-treat basis at 30 days and 1 year. The average duration of graft occlusion was 34.0 days, with 58 (48%) presenting with acute ischemia (0 to 14 days) and 64 (52%) with chronic ischemia (> 14 days). Thirty-nine percent randomized to lysis failed catheter placement and required surgical revascularization. Overall, there was a better composite clinical outcome at 30 days (P = 0.023) and 1 year (P = 0.04) in the surgical group compared with lysis, due predominately to a reduction in ongoing/recurrent ischemia, most notable in autogenous grafts. However, following successful catheter placement, patency was restored by lysis in 84%, and 42% had a major reduction in their planned operation. One-year results of successful lysis compared favorably with the best surgical procedure, which was new graft placement. Acutely ischemic patients (0 to 14 days) randomized to lysis demonstrated a trend toward a lower major amputation rate at 30 days (P = 0.074) and significantly at 1 year (P = 0.026) compared with surgical patients, while those with > 14 days ischemia showed no difference in limb salvage but higher ongoing/recurrent ischemia in lytic patients (P < 0.001). Patients with occluded prosthetic grafts had greater major morbidity than did those with occluded autogenous grafts (P < 0.02). Proper catheter positioning currently limits the potential of catheter-directed thrombolysis for lower extremity bypass graft occlusion. Patients with graft occlusion > 14 days have a significantly better outcome when treated surgically, with a new bypass being the best surgical option. However, in patients with acute limb ischemia (< 14 days) successful thrombolysis of occluded lower extremity bypass grafts improves limb salvage and reduces the magnitude of the planned surgical procedure. Patients with occluded prosthetic grafts suffer more major morbid events compared with occluded autogenous grafts.