Systematic literature review comparing clinical utility of heparin-bonded expanded polytetrafluoroethylene graft with autologous saphenous vein graft for the management of below-the-knee peripheral arterial disease.

BACKGROUND: This systematic literature review compares the clinical outcomes of heparin-bonded expanded polytetrafluoroethylene with autologous saphenous vein in the management of patients undergoing below-the-knee bypass to treat peripheral arterial disease. METHODS: An electronic literature search was conducted in MEDLINE and Embase to identify comparative studies in patients who underwent below-the-knee surgical bypass. Studies were screened at abstract and full text review using predefined inclusion criteria by two independent reviewers and critically appraised for risk of bias. Meta-analyses were conducted using Review Manager 5 software (Nordic Cochrane Centre). RESULTS: Eight retrospective cohort studies were identified. Meta-analysis of primary patency demonstrated no significant difference between heparin-bonded expanded polytetrafluoroethylene and autologous saphenous vein grafts after 1 (odds ratio: 0.91, 95% confidence interval: [0.52-1.59]; P = .74), 2 (1.12 [0.60-2.10]; P = .77), 3 (0.62 [0.26-1.48]; P = .28), and 4 years (0.70 [0.36-1.39]; P = .31). Similarly, for secondary patency, no significant difference was detected at 1 (0.62 [0.33-1.15]; P = .13), 2 (0.83 [0.32-2.13]; P = .69), 3 (0.60 [0.27-1.32]; P = .20), and 4 years (0.66 [0.32-1.36]; P = .26). There was no significant difference between autologous veins and heparin-bonded expanded polytetrafluoroethylene for limb salvage and mortality at all time points. A sensitivity analysis to compare outflow vessels was conducted in only tibial bypass and identified no differences. All analyses were considered at high-risk bias because of heterogeneity in study populations and attrition in follow-up. CONCLUSIONS: This meta-analysis demonstrates similar outcomes between autologous saphenous vein and heparin-bonded expanded polytetrafluoroethylene for patency, limb salvage, and mortality through 4 years. The use of heparin-bonded expanded polytetrafluoroethylene synthetic grafts is a satisfactory option to prevent amputation, particularly when autologous saphenous vein grafts are not available. Controlled clinical studies are needed to further inform future decision-making and economic modeling related to the choice of conduit for below-the-knee graft construction.

Learning curve and proficiency metrics for transcarotid artery revascularization.

BACKGROUND: When introduced to a new procedure, physicians improve their performance and reduce their procedural adverse event rates rapidly during the initial cases and then improvement slows, signaling that proficiency has been achieved. Determining when they have acquired proficiency has important implications for procedural innovation, education, credentialing, and patient safety. We analyzed the worldwide experience with transcarotid artery revascularization (TCAR), a hybrid approach to carotid revascularization, to identify the (1) procedural performance measures associated with clinical and technical adverse events; (2) target levels of performance measures that minimize adverse event rates; and (3) number of TCAR cases needed to achieve the target levels for the performance measures. METHODS: The patient, lesion, and physician characteristics were collected for each TCAR procedure performed by each physician worldwide in an international quality assurance database. Four procedural performance measures were recorded for each procedure: flow-reversal time, fluoroscopy time, contrast volume, and total skin-to-skin time. Composite clinical adverse events (ie, transient ischemic attack, stroke, myocardial infarction, death) and composite technical adverse events (ie, aborted procedure, conversion to surgery, bleeding, dissection, cranial nerve injury, device failure), occurring within 24 hours were also recorded. Correlations between each performance measure and the clinical and technical adverse event rates were computed. The inflection points in the performance measures were identified at which no further improvements occurred in the adverse event rates. Finally, the minimum number of TCAR cases required to achieve the target performance measure levels was computed. RESULTS: A total of 18,240 procedures performed by 1273 physicians were analyzed. Of the 18,240 patients, 34.9% were women and 62.5% were asymptomatic. The flow-reversal time correlated with clinical adverse events adjusted for age, sex, and symptomatic status (R2 = 0.91; P < .0001) and adjusted technical adverse events (R2 = 0.86; P < .0001). The skin-to-skin time correlated with adjusted technical adverse events (R2 = 0.92; P < .0001). A reduction in flow-reversal times to <13.1 minutes and the skin-to-skin time to <81 minutes did not translate into further improvements in the adverse event rates. A minimum of 26 TCAR cases was required to achieve the target flow-reversal time, and a minimum of 15 cases was required to achieve the target skin-to-skin time. CONCLUSIONS: The flow-reversal time and skin-to-skin time are appropriate performance measures for establishing the level of expertise of physicians as they acquire skills to perform TCAR. A target time of ≤13.1 minutes for flow-reversal and 81 minutes for skin-to-skin time minimized the adverse event rates. Familiarity with the steps involved in performing TCAR was achieved after ≥15 cases, and minimizing clinical adverse events occurred after ≥26 cases.

The impact of the SARS-CoV-2 pandemic on the management of chronic limb-threatening ischemia and wound care.

In the wake of the coronavirus pandemic, the critical limb ischemia (CLI) Global Society aims to develop improved clinical guidance that will inform better care standards to reduce tissue loss and amputations during and following the new SARS-CoV-2 era. This will include developing standards of practice, improve gaps in care, and design improved research protocols to study new chronic limb-threatening ischemia treatment and diagnostic options. Following a round table discussion that identified hypotheses and suppositions the wound care community had during the SARS-CoV-2 pandemic, the CLI Global Society undertook a critical review of literature using PubMed to confirm or rebut these hypotheses, identify knowledge gaps, and analyse the findings in terms of what in wound care has changed due to the pandemic and what wound care providers need to do differently as a result of these changes. Evidence was graded using the Oxford Centre for Evidence-Based Medicine scheme. The majority of hypotheses and related suppositions were confirmed, but there is noticeable heterogeneity, so the experiences reported herein are not universal for wound care providers and centres. Moreover, the effects of the dynamic pandemic vary over time in geographic areas. Wound care will unlikely return to prepandemic practices. Importantly, Levels 2-5 evidence reveals a paradigm shift in wound care towards a hybrid telemedicine and home healthcare model to keep patients at home to minimize the number of in-person visits at clinics and hospitalizations, with the exception of severe cases such as chronic limb-threatening ischemia. The use of telemedicine and home care will likely continue and improve in the postpandemic era.

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

BACKGROUND: 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. METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

Novel Therapies for Critical Limb-Threatening Ischemia.

PURPOSE OF REVIEW: This review intends to discuss the latest endovascular and surgical advancement in the treatment of critical limb-threatening ischemia (CLTI). RECENT FINDINGS: We discuss novel endovascular technological advancements such as intravascular lithotripsy, the Tack endovascular stent, the PQ Bypass DETOUR system, and the LimFlow System for deep venous arterialization (DVA) in the very high risk "no-option" CLTI population. We also discuss the increasing adoption of radial and pedal approaches for endovascular revascularization and the tibiopedal arterial minimally invasive (TAMI) technique. On the surgical front, we discuss the distal vein patch technique and surgical and hybrid DVA. Recent advancements in the treatment options of CLTI will likely lead to reducing the rate of major amputations if they are adopted in a collaborative environment in order to apply the most appropriate treatment option to each individual patient based on the anatomy, comorbidities, functional status, and local expertise.

Digital Subtraction Angiography Prior to an Amputation for Critical Limb Ischemia (CLI): An Expert Recommendation Statement From the CLI Global Society to Optimize Limb Salvage.

Despite recent guideline updates on peripheral artery disease (PAD) and critical limb ischemia (CLI) treatment, the optimal treatment for CLI is still being debated. As a result, care is inconsistent, with many CLI patients undergoing an amputation prior to what many consider to be mandatory: consultation with an interdisciplinary specialty care team and a comprehensive imaging assessment. More importantly, quality imaging is critical in CLI patients with below-the-knee disease. Therefore, the CLI Global Society has put forth an interdisciplinary expert recommendation for superselective digital subtraction angiography (DSA) that includes the ankle and foot in properly indicated CLI patients to optimize limb salvage. A recommended imaging algorithm for CLI patients is included.

Initial in vitro and in vivo evaluation of a self-monitoring prosthetic bypass graft.

OBJECTIVE: Prosthetic grafts used for lower extremity revascularization and dialysis access fail because of hyperplastic stenosis and thrombosis. Graft surveillance is advocated to monitor function; however, graft failure can occur between episodic examinations. An innovative sensor with wireless, microchip technology allows automated surveillance with assessment of graft function using a "cloud"-based algorithm. We performed proof-of-concept experiments with in vitro and in vivo models to assess the feasibility such a real-time graft surveillance system. METHODS: A self-monitoring graft system was evaluated consisting of a prosthetic conduit of expanded polytetrafluoroethylene and a sensor unit, and a microsensor, microelectronics, battery, and remote processor with a monitor. The sensor unit was integrated on the extraluminal surface of expanded polytetrafluoroethylene grafts without compromise to the lumen of the conduit. The grafts were tested in vitro in a pulsatile, recirculating flow system under physiologic flow parameters. The hemodynamic parameters were varied to assess the ability to obtain wireless signal acquisition reflecting real-time flow properties in vitro. Segments of custom tubing with reduced diameters were inserted into the model to mimic stenosis proximal and distal to the grafts. After characterization of the initial data, the self-monitoring grafts were implanted in an ovine carotid model to assess proof of concept in vivo with 30-day follow-up of signal acquisition as well as arteriographic and histologic analysis. RESULTS: In vitro flow data demonstrated the device was able to determine factors related to prosthetic graft function under varied hemodynamic flow conditions. Wireless signal acquisition using Bluetooth technology (Bluetooth SIG, Inc, Kirkland, Wash) allowed remote data analysis reflecting graft flow parameters through changes in microsensor voltage and frequency. Waveform analysis was applied to construct an algorithm using proprietary software and determine a parameter for graft flow characteristics. This algorithm allowed determination of the degree of stenosis and location of stenosis location (proximal or distal) for display on a remote monitor in real time. Subsequent in vivo experiments confirmed the ability of the system to generate signal acquisition through skin and soft tissue under biologic conditions with no arteriographic stenosis and a favorable healing response at 30-day harvest. CONCLUSIONS: Initial in vitro and in vivo experiments demonstrate the ability for a self-monitoring graft system to remotely monitor hemodynamic parameters reflecting graft function using wireless data transmission. This automated system shows promise to deliver real-time data that can be analyzed by cloud-based algorithms alerting the clinician of a change in graft function or development of stenosis for further diagnostic study or intervention before graft failure.

Development of a Limb-Preservation Program.

In the global scenario, as the prevalence of renal failure and diabetes increases, healing and limb preservation assume increasing clinical importance for patients and healthcare systems. Unfortunately, there continues to be variation in the care delivered to patients at risk of losing a limb based on geography, race, socioeconomic status, and insurance status. There are also a variety of therapeutic approaches to patients with limb-threatening ischemia; 25% undergo primary amputation, 25% undergo medical therapy, and only 50% undergo any attempt at revascularization. Nearly 50% of patients undergoing major amputation have not had a simple diagnostic arteriogram to assess the possibility of limb preservation. The Society of Vascular Surgery and the American Podiatric Medical Association have recognized the benefits of a multidisciplinary approach to limb preservation. Benefits to the patient include rapid assessment, improved healing, and enhanced revascularization. Advantages for the providers include the ability to efficiently manage complex patients with help from the appropriate specialties, an increase in referrals, enhanced identity of the institution, and clinical research and trials. Such a program requires the coordinated effort of physicians, nurses, allied health professionals, and administrators dedicated to the preservation of functional limbs. Beneficial components include identifiable space, a vascular laboratory, hyperbaric oxygen therapy, and protocol-driven care involving diagnostic and therapeutic modalities such as endovascular revascularization, open bypass, and soft tissue reconstruction. Prosthetic expertise is also important to maintain function in those patients for whom amputation is appropriate. But, the key to a program is cooperation and communication among the participants who have a passion for limb preservation. Video Journal Club 'Cappuccino with Claudio Ronco' at http://www.karger.com/?doi=452746.

Postoperative complications after common femoral endarterectomy.

BACKGROUND: Common femoral endarterectomy (CFE) for limited arterial occlusive disease is considered a fairly low-risk operation of short duration. This study investigated the timing of 30-day outcomes as they related to hospital discharge and predicted the risk of operative mortality of this procedure. METHODS: All patients in the National Surgical Quality Improvement Program database who underwent isolated CFE between 2005 and 2010 were selected for the test sample. We identified postoperative mortality and morbidities occurring before and after hospital discharge. A risk calculator for 30-day mortality, developed in the test sample using logistic regression, was validated in a new sample of cases from 2011 to 2012. RESULTS: A total of 1843 CFEs reported from 2005 to 2010 met the inclusion and exclusion criteria. The average operative time was 146 ± 69.5 minutes (median, 133; interquartile range, 98-179 minutes), and 10% of patients needed to return to the operating room. The average length of stay was 4 ± 7.5 days (median, 3; interquartile range, 2-5 days); 91% of patients were discharged ≤ 1 week of surgery. Occurrences of cardiovascular events, renal dysfunction, and pulmonary complication were relatively low. There was 3.4% mortality and 8% wound-related complications, 30% and 86% of which occurred after hospital discharge, respectively. Overall, there was a 15% risk of combined mortality/morbidity, and >60% of these events occurred after discharge. The independent predictors of 30-day mortality were age, nonindependent functional status, preoperative dialysis, sepsis, emergency status, and American Society of Anesthesiologists Physical Status Classification 4 or 5, and the association between risk strata and death in the validation sample was strong (φ = 0.29) and significant (P < .001). CONCLUSIONS: CFE is not as "benign" a procedure as previously believed. The risks of death and wound complications are not insignificant, and a high percentage of these complications occurred after patients were discharged from the hospital. Patients should be carefully selected, especially in the elderly population, and close postoperative follow-up should be considered.

The effect of graft configuration on 30-day failure of infrapopliteal bypasses.

BACKGROUND: Despite advances in endovascular techniques, infrapopliteal bypasses are still required for limb salvage. Short-term graft patency is an important outcome parameter reflecting technical considerations and acute graft thrombosis. Both are important prerequisites for long-term patency. In this analysis, we compared the 30-day patency of all conduit configurations for infrapopliteal bypasses. METHODS: All primary infrapopliteal bypasses from the American College of Surgeons-National Surgical Quality Improvement Program database between 2005 and 2010 were divided into six groups: (1) great saphenous vein (GSV); (2) prosthetic conduit (prosthetic); (3) prosthetic conduit with a distal anastomotic venous adjunct (ADJ), such as a cuff or patch (prosthetic + ADJ); (4) composite graft of prosthetic and a vein segment (composite); (5) spliced autogenous vein (spliced vein); and (6) arm vein. Thirty-day graft failure, patient demographics, and operative details were compared among groups. A multivariate model was used for statistical analysis. RESULTS: A total of 5375 infrapopliteal bypasses were analyzed by conduit: GSV, 3983 (75%); prosthetic, 898 (17%); spliced vein, 160 (3%); prosthetic + ADJ, 112 (2%); arm vein, 93 (2%); and composite, 91 (2%). The difference among groups in demographics and comorbidities was not statistically significant. Perioperative mortality rates were similar among different conduits. After adjusting for sex, age, weight, race, and previous cardiac surgery, the bypass conduit had a significant independent association with 30-day graft patency (P = .006). The GSV failure rate was 7.5%. Composite had a significantly higher 30-day failure rate (15.4%, P = .006). There was no significant difference in 30-day failure rate of spliced vein (5.6%, P = .37) or arm vein (4.3%, P = .24) conduits compared with GSV. Prosthetic had significantly higher 30-day failure rate than GSV (10.5%, P = .004). The addition of adjuvant venous tissue at the distal anastomosis of prosthetic bypasses did not significantly improve their 30-day patency (failure rate of 9.8% for prosthetic + ADJ and 10.5% for prosthetic). There was no significant difference in graft patency between alternative venous conduits (arm vein/spliced vein) and prosthetic + ADJ. CONCLUSIONS: Venous conduits (GSV, spliced vein, arm vein) deliver the best 30-day patency for infrapopliteal bypasses, and GSV remains the most commonly used graft. Prosthetic grafts had a higher 30-day failure rate. Composite grafts should be abandoned because their early patency is not better than pure prosthetic conduits. The addition of a distal venous adjunct did not seem to improve acute prosthetic graft patency, which may reflect lack of effect on thrombogenicity rather than the myointimal hyperplastic response that effects long-term failure of infrapopliteal bypass.

Management of peripheral arterial disease in the context of a multidisciplinary limb program.

Peripheral artery disease (PAD) continues to increase in prevalence worldwide due to risk factors such as advanced age, diabetes mellitus, and obesity. Critical limb ischemia (CLTI) is the advanced form of PAD that can result in a lack of healing and limb loss as the most devastating consequence. Patients with PAD, especially CLTI, benefit from multidisciplinary care to optimize outcomes by reducing cardiovascular morbidity and mortality and preventing lower extremity amputation. Collaboration between various specialties allows a focus on problems involved in treating the patient with PAD including prevention, screening, medical care, wound care, infection, and revascularization when needed. Although there is no clear definition or consensus on the structure of the PAD team, certain guidelines are applicable to most clinical scenarios emphasizing "provider champions" in leading a clinical program. A vascular specialist (vascular surgery, interventional radiology, interventional cardiology) and a soft tissue specialist (podiatry, plastic surgery) are the typical "champions," often involving orthopedics, general surgery, vascular medicine, diabetology/endocrinology, infectious disease, nephrology, and rehabilitation medicine. The team should also include wound nurses, nutritionists, occupational therapists, orthotists, pharmacists, physical therapists, prosthetists, and social workers. This paper presents a brief overview of the structure of the multidisciplinary team with key components and functions of such a team to optimize treatment outcomes for PAD and CLTI.

Comparison of outcomes for open abdominal aortic aneurysm repair and endovascular repair in patients with chronic renal insufficiency.

OBJECTIVE: This study investigates whether this practice is supported by multicenter prospectively collected data. BACKGROUND: Currently, open abdominal aortic aneurysm (AAA) repair (OPEN) is preferred over endovascular repair (EVAR) in patients with chronic renal insufficiency because of the concern that the contrast load used for EVAR may result in postoperative dialysis. METHODS: Patients who underwent EVAR and OPEN for infrarenal AAA were identified in the NSQIP database from 2005 to 2010. Preoperative renal function was assessed by estimated glomerular filtration rate (eGFR) calculated by the Chronic Kidney Disease Epidemiology Collaboration equation. Patients with chronic renal insufficiency were further stratified into 2 different groups: moderate (eGFR = 30-60 mL/min) and severe (eGFR <30 mL/min) renal dysfunction. Multivariate regression model was used for data analysis. RESULTS: We identified 13,191 patients who underwent AAA repair: 9877 patients underwent EVAR and 3314 underwent OPEN. Forty percent of patients had eGFR of less than 60 mL/min. OPEN in patients with moderate renal dysfunction resulted in significantly higher mortality, cardiovascular events, and combined outcomes. However, in patients with severe renal dysfunction, these outcomes were similarly high in both OPEN and EVAR. Most importantly, OPEN in patients with moderate renal dysfunction resulted in 5.2 times higher risk of dialysis. CONCLUSIONS: Contrary to current practice, and despite the use of contrast, EVAR should be the first choice in patients with moderate renal dysfunction if they have the appropriate anatomy. Higher threshold for AAA repair with either OPEN or EVAR should be applied in patients with severe renal dysfunction because postoperative complications were significantly high with either approach.

A comparison of tibial artery bypass performed with heparin-bonded expanded polytetrafluoroethylene and great saphenous vein to treat critical limb ischemia.

BACKGROUND: Expanded polytetrafluoroethylene (ePTFE) bonded with heparin (HePTFE) has been reported to perform equivalent to saphenous vein graft (SVG) for below-knee bypass. This series examines outcomes for tibial artery bypass using HePTFE and SVG over a contemporaneous time period. METHODS: A retrospective analysis of prospectively collected data was conducted for 112 tibial bypasses (62 HePTFE, 50 SVG) performed from November 2006 to January 2009. Demographics for age, sex, race, diabetes mellitus, and end-stage renal disease were similar. Indications for revascularization were also similar: disabling claudication, 9%; rest pain, 25%; and tissue loss, 66%. The HePTFE group included more reoperative procedures (45% vs 26%). All HePTFE bypasses were performed using an autologous vein patch at the distal anastomosis. Postoperative graft surveillance by pulse examination, ankle-brachial index, and duplex ultrasound imaging occurred at 1, 3, 6, and 12 months. Follow-up ranged from 1 to 12 months. Kaplan-Meier and Cox regression analysis evaluated results in patients with no missing variables. RESULTS: HePTFE and SVG bypasses demonstrated no significant differences in target tibial artery distribution: anterior tibial (15 vs 17), dorsalis pedis (4 vs 5), posterior tibial (22 vs 16), and peroneal (21 vs 12). Graft occlusion occurred in 19 patients (16.9%) during follow-up. Primary patency at 1 year was 75.4% for HePTFE and 86.0% for SVG. There was no significant difference in primary patency due to sex (male, 78%; female, 84%), race (white, 82%; African American, 77%), or diabetes mellitus (no diabetes mellitus, 84%; diabetes mellitus, 76%). End-stage renal disease resulted in decreased patency (57%), with an eightfold reduction (95% confidence interval, 1.8%-39.8%; P = .006). SVG patients had a lower risk of occlusion/death (95% confidence interval, 14.2%-94.5%; P > .05). Sixteen amputations were performed, with no significant difference based on conduit. CONCLUSIONS: This experience indicates a trend for single-segment quality saphenous vein to remain the conduit of choice for tibial artery bypass compared with HePTFE. Factors relevant to decreased 1-year patency for the entire cohort were end-stage renal disease and nonhealing ulceration as the indication for revascularization. Although relatively short-term, these results do support HePTFE as a viable alternative conduit for patients with absent or poor quality saphenous vein who need a tibial bypass.

Hemodynamic comparison of differing anastomotic geometries using magnetic resonance velocimetry.

BACKGROUND: Hemodynamic factors at the distal anastomosis play an important role in prosthetic graft performance. A new magnetic resonance imaging (MRI) technique was used to determine the effect of anastomotic geometry on hemodynamic flow patterns. METHODS: Four dimensional (4D) magnetic resonance velocimetry (4D-MRV) is a noninvasive method of analyzing pulsatile flow in three dimensions (3D). End-to-side anastomotic models were constructed by suturing 6 mm polytetrafluoroethylene (ePTFE) grafts to silicone tubing (4 mm i.d.). The models included straight ePTFE, precuffed ePTFE, and patched ePTFE configurations in a pulsatile system, which created flow consistent with physiologic flow rates and pressures. Blood was simulated by a solution of 40% glycerol in distilled water with trace gadolinium. The different models were imaged using MRV techniques in a three-dimensional (3D) coronal slab (0.5 mm thick coronal slices, in-plane field of view (FOV) 18 cm.) The data were reconstructed, resulting in an interpolated resolution of 0.35 mm in each coronal plane. The 3D flow fields were represented as isosurfaces, visualizing the internal geometry of the models with streamlines tangent to the velocity vectors identifying the path of the fluid. Volumetric flow rates for each time phase were calculated by integrating the flow through cross sections of each anastomotic model. Analysis of the flow patterns focused on the anastomotic regions prone to the development of intimal hyperplasia and graft failure as identified in the literature; the toe, floor, heel, and hood. RESULTS: Conventional end-to-side geometry resulted in uniform flow with a low angle of impingement on the recipient vessel floor. A small vortex at the anastomotic heel created minimal recirculation. The precuffed geometry resulted in a large recirculation vortex of chaotic, low flow that increased throughout the pulsatile cycle. Regions of low flow velocity were noted in a substantial portion of the precuffed anastomotic configuration. Flow separation distal to the toe occurred in both geometries, but was more apparent in the precuffed configuration. The patch model had flow characteristics similar to the straight end-to-side geometry. CONCLUSION: Magnetic resonance velocimetry produces 3D, time varying velocity measurements with sufficient accuracy and resolution to analyze hemodynamics in anastomotic geometries. Flow structures in different graft configurations were effectively captured with marked differences noted between standard and precuffed anastomotic geometries. The findings support a conventional end-to-side anastomosis with a low incidence angle using a straight graft as producing favorable hemodynamics as compared to a cuffed configuration. The vein patch configuration closely approximates the conventional, straight anastomotic pattern. We believe the MRV technique has been sufficiently developed to warrant additional in vitro and in vivo studies providing insight into hemodynamic implications for the development of optimal prosthetic graft performance.

The Significance of the Global Vascular Guidelines for Podiatrists: Answers to Key Questions in the Diagnosis and Management of the Threatened Limb.

The publication of the Global Vascular Guidelines in 2019 provide evidence-based, best practice recommendations on the diagnosis and treatment of chronic limb-threatening ischemia (CLTI). Certainly, the multidisciplinary team, and more specifically one with collaborating podiatrists and vascular specialists, has been shown to be highly effective at improving the outcomes of limbs at risk for amputation. This article uses the Guidelines to answer key questions for podiatrists who are caring for the patient with CLTI.

Modern multidisciplinary team approach is crucial in treatment for critical limb threatening ischemia.

The aim of this study was to provide a brief overview of the history the multidisciplinary team approach, highlighting the benefit to the patient with critical limb threatening ischemia in relation to health care economics. Furthermore, we provided a description of the requisites and key components, showing how to build a multidisciplinary team.

Distal vein patch with an arteriovenous fistula: a viable option for the patient without autogenous conduit and severe distal occlusive disease.

BACKGROUND: The addition of a distal arteriovenous fistula (DAVF) to improve patency in lower extremity bypass is well described. This report describes a technique of using a distal AVF to enhance a distal vein patch (DVP) in patients without adequate autogenous conduit and who have concomitant severely disadvantaged arterial runoff. METHODS: A retrospective review from May 2002 to May 2007 analyzed 270 tibial bypasses. DVP-AVF was the conduit in 30 bypass grafts. Patient demographics included 16 men, 14 women, diabetes mellitus (67%), and chronic renal failure (20%). All patients had limb-threatening ischemia manifest as rest pain or tissue loss, with 20 patients referred after failed prior revascularization: 11 failed bypasses, and nine failed endovascular interventions. In each case, the only outflow artery available was an isolated tibial segment or a diseased pedal vessel not ordinarily deemed suitable for bypass. At surgery, a common ostium AVF was created between the outflow tibial artery and corresponding tibial vein before DVP construction. Follow-up was 1 to 24 months, with graft function evaluated by pulse examination and duplex surveillance. Primary patency and limb salvage +/- SE were determined by life-table analysis using Rutherford criteria. RESULTS: The proximal anastomosis originated from the external iliac (23%), common femoral artery (43%), and superficial femoral artery (33%). Outflow arteries included the anterior tibial (40%), posterior tibial (30%), and peroneal (30%). Venous hypertension in the bypassed limb was noted, but not considered problematic in any patient. Perioperative graft failure occurred in one patient. Six graft failures led to six major amputations (1 above knee; 5 below knee). One patent graft was excised due to infection. Primary patency at 6, 12, 18, and 24 months was 78.3% +/- 6.8%, 78.3% +/- 10.5%, 62.6% +/- 11.1%, and 62.6% +/- 15.6%; limb salvage was 78.7% +/- 6.7%, 78.7% +/- 10.1%, 78.7% +/- 10.1%, and 57.7% +/- 12.5%. CONCLUSION: This early experience describes a modification of the DVP technique in patients with threatened limb loss and severely disadvantaged tibial runoff. The addition of an AVF may reduce outflow resistance, thereby contributing to higher flow rates and improved graft patency. Further investigation is warranted because the DVP-AVF technique may result in acceptable graft patency and limb salvage for patients with no other alternative than amputation.