Hemodynamics and Wall Mechanics of Vascular Graft Failure.

Blood vessels are subjected to complex biomechanical loads, primarily from pressure-driven blood flow. Abnormal loading associated with vascular grafts, arising from altered hemodynamics or wall mechanics, can cause acute and progressive vascular failure and end-organ dysfunction. Perturbations to mechanobiological stimuli experienced by vascular cells contribute to remodeling of the vascular wall via activation of mechanosensitive signaling pathways and subsequent changes in gene expression and associated turnover of cells and extracellular matrix. In this review, we outline experimental and computational tools used to quantify metrics of biomechanical loading in vascular grafts and highlight those that show potential in predicting graft failure for diverse disease contexts. We include metrics derived from both fluid and solid mechanics that drive feedback loops between mechanobiological processes and changes in the biomechanical state that govern the natural history of vascular grafts. As illustrative examples, we consider application-specific coronary artery bypass grafts, peripheral vascular grafts, and tissue-engineered vascular grafts for congenital heart surgery as each of these involves unique circulatory environments, loading magnitudes, and graft materials.

Autologous Alternative Vein Grafts for Infrainguinal Bypass in the Absence of Single-Segment Great Saphenous Vein: A Single-Center Study.

BACKGROUND: Alternative autologous veins can be used as a conduit when adequate great saphenous vein is unavailable. We analyzed the results of our infrainguinal bypasses after adopting upper extremity veins in our practice. METHODS: This is a single-center observational study involving all patients whose infrainguinal bypass involved the use of upper extremity veins between April 2019, when we began using arm veins, and February 2023. RESULTS: During the study period, 49 bypasses were done in 48 patients; mean age 68.1 ± 9.8; men 32 (66.7%); body mass index 28.0 ± 4.8; indications for surgery: chronic limb threatening ischemia 41 (83.7%); acute limb ischemia 3 (6.1%); complications of previous prosthetic 3 (6.1%), or autologous 2 (4.1%) bypass grafts. Vein splicing was used in 43 (87.8%) bypasses with 3-segment grafts being the most common (26; 53.1%). There were 24 (49.0%) femorotibial, 11 (22.4%) femoropopliteal, 9 (18.4%) femoropedal, and 5 (10.2%) extension jump bypass procedures. Eighteen (36.7%) operations were redo surgeries. Twenty-one (42.9%) bypasses were formed using only arm veins. The median follow-up was 12.9 months (4.5-24.2). Two bypasses occluded during the first 30 postoperative days (2/49; 4.1%). Overall 30-day, 1-year, and 2-year primary patency rates were 93.7% ± 3.5%, 84.8% ± 5.9%, and 80.6% ± 6.9%, and secondary patency (SP) rates were 95.8% ± 2.9%, 89.2% ± 5.3%, and 89.2% ± 5.3%. One-segment grafts had better patencies than 2-, 3-, and 4-segment grafts (1-year SP 100% ± 0% vs 87.6% ± 6.0%). Two-year amputation-free survival was 86.8% ± 6.5%; 2-year overall survival was 88.2% ± 6.6%. CONCLUSIONS: Integration of arm vein grafts in infrainguinal bypass practice can be done safely with low incidences of perioperative graft failure. One-segment grafts had better patencies than spliced vein grafts. The achieved early patency and amputation-free survival rates strongly encourage their use. In the absence of a single-segment great saphenous vein, upper extremity vein grafts should be the preferred conduit choice.

Arteriovenous Fistula Maturation in Patients with Ipsilateral Versus Contralateral Tunneled Dialysis Catheter: A Systematic Review and Meta-analysis.

BACKGROUND: Although it is evident that a prior history of tunneled dialysis catheter (TDC) affects arteriovenous fistula (AVF) function, it is unclear whether its location (contralateral versus ipsilateral to AVF) has any effect on AVF maturation and failure rates. We aimed to document this possible effect. METHODS: This systematic review and meta-analysis were performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies comparing outcomes between patients with contralateral TDC (CONTRA group) and those with ipsilateral one (IPSI group) were examined for inclusion. A random effects model meta-analysis of the odds ratio (OR) was conducted. Primary outcomes were AVF functional maturation, assisted maturation, and failure rates. RESULTS: Four eligible studies comprising 763 patients were included in the meta-analysis. There were no significant differences in terms of AVF functional maturation (OR: 1.49; 95% confidence interval [CI]: 0.64-3.47; I2 = 83.4%), assisted maturation (OR: 0.59; 95% CI: 0.29-1.19; I2 = 61.4%), and failure rates (OR: 0.67; 95% CI: 0.29-1.58; I2 = 83.3%) between the 2 study groups. CONCLUSIONS: TDC laterality seems not to affect fistula maturation rate in patients requiring TDC placement and concurrent AVF creation, but rather, vein- and patient-related characteristics might play a more important role in choosing TDC access site. Further studies are needed to validate these results.

Influence of lipoproteins and antiplatelet agents on vein graft patency 1 year after coronary artery bypass grafting.

OBJECTIVE: It remains unclear whether aggressive low-density lipoprotein cholesterol (LDL-C) management (<1.8 mmol/L) can slow the process of vein graft stenosis. This study aimed to explore the impact of baseline LDL-C levels on vein graft patency in patients on ticagrelor with or without aspirin 1 year after coronary artery bypass grafting (CABG). METHODS: This was a post hoc analysis of the DACAB (Different Antiplatelet Therapy Strategy After Coronary Artery Bypass Graft Surgery) trial (NCT02201771), a randomized controlled trial (ticagrelor + aspirin or ticagrelor vs aspirin) of patients undergoing CABG in China. The study subjects were stratified as LDL-low (baseline LDL-C <1.8 mmol/L, 148 patients with 430 vein grafts) versus LDL-high (baseline LDL-C ≥1.8 mmol/L, 352 patients with 1030 vein grafts). The primary outcome was the 1-year vein graft patency (Fitzgibbon grade A) assessed by coronary computed tomographic angiography or coronary angiography. RESULTS: Baseline/1-year LDL-C were 1.4/1.6 and 2.6/2.4 mmol/L in the LDL-low and LDL-high subgroups, respectively. Regardless of antiplatelet regimen, no significant inter-subgroup difference was observed for 1-year graft patency (LDL-low: 83.8% [359/430 grafts]; LDL-high: 82.3% [848/1030 grafts]; adjusted OR for non-patency [ORadj], 0.96; 95% confidence interval [CI], 0.62-1.50, P = .857). For both subgroups, the 1-year graft patency rates were greater with ticagrelor + aspirin versus aspirin (LDL-low: ORadj, 0.41; 95% CI, 0.17-0.97; LDL-high: ORadj, 0.38; 95% CI, 0.20-0.71; inter P = .679). CONCLUSIONS: In general, baseline LDL-C is not associated with 1-year vein graft patency after CABG. Regardless of the baseline LDL-C levels, ticagrelor + aspirin was superior to aspirin alone in maintaining vein graft patency. The primary factor causing early vein graft disease might not be atherosclerosis but thrombosis.

The predictive value of microperfusion assessments for the follow-up of tibial bypass grafts.

OBJECTIVE: We conducted a prospective evaluation of microperfusion parameters after tibial bypass surgery was performed. Differences between grafts with occlusions during follow-up and patent grafts were analyzed in relation to the pedal arch quality. METHODS: Patients receiving tibial bypass grafts for chronic limb-threatening ischemia from 2019 to 2020 were included. Assessment of microcirculation (parameters: hemoglobin oxygen saturation [sO2] and flow) was done by laser Doppler flowmetry and white light spectrometry (oxygen-to-see), supine and in elevation, whereas the macrocirculation was evaluated by the ankle-brachial index and duplex ultrasound examination. The quality of run-off was graded for each patient. Measurements were performed preoperatively, 1 day postoperatively, and after 6 months. Patients with graft occlusions during follow-up (OCCLUDED) and patients without occlusions (OPEN) were compared. RESULTS: We included 42 patients (13 women, 29 men; mean age, 76.1 years; range, 60-89 years) were included. The patency of all grafts 1 day after the operation was confirmed by ultrasound examination. The overall analysis of the microcirculation showed significant changes in both the supine and elevated leg position between measurements taken preoperatively, 1 day after the operation, and after 6 months for the parameters sO2 and FLOW (sO2 supine, P = .001; sO2 elevated, P < .001; FLOW supine, P < .001; FLOW elevated, P < .001). The comparison of the values 1 day after the operation yielded significantly decreased microperfusion parameters (both O2 and FLOW) in the group that developed bypass occlusion in the later follow-up period (sO2 supine: OCCLUDED, 35.7% [7.3-65.0] and OPEN, 48.7% [25.0-72.3] P = .011; FLOW supine: OCCLUDED, 27.7 A.U. [12.7-52.7] and OPEN, 57.3 A.U. [16.0-106.7], P = .008). No significant differences in the severity of the arch impairment was found between the OPEN and OCCLUDED groups (P = .651). Absolute values of the parameters sO2 and flow showed no correlation with the pedal arch classification. CONCLUSIONS: Significantly poorer microperfusion was detected postoperatively in patients with later occurrence of graft occlusions despite patent grafts on the first postoperative day. Microperfusion measurements might be a possible tool for the prediction of graft failure.

Evaluation of Long-Term Outcomes of Femoropopliteal Bypass Surgery in Patients With Chronic Limb-Threatening Ischemia in an Endovascular Era.

BACKGROUND: To investigate the long-term outcomes of femoropopliteal bypass surgery in patients with chronic limb-threatening ischemia (CLTI) and TransAtlantic Inter-Society Consensus II (TASC II), type D (TASC D) femoropopliteal disease. METHODS: A retrospective analysis was performed for all consecutive patients undergoing above-knee (AK) femoropopliteal bypass surgery at an academic vascular centre between January 2007 and March 2019. Patients with claudication (IC) and patients with CLTI were included. Patency rates and freedom from major adverse limb events (MALE) after 5 years were analysed. RESULTS: In total, 432 femoropopliteal grafts were performed. Indications for surgery were claudication and CLTI in 232 (53.7%) and 200 (46.3%) patients, respectively. Graft material was autologous vein in 186 patients (43.1%), polytetrafluoroethylene (PTFE) in 128 patients (29.6%), and heparin-bonded expanded polytetrafluoroethylene (HePTFE) in 118 patients (27.3%). At the 5-year follow-up, the primary patency rate was 58.1% and 58.3% in patients with CLTI and claudication, respectively. Secondary patency rates were 74.1% and 68.6%, respectively. Freedom from MALE was 64.5% and 61.9%, respectively. Analyses of graft material in the CLTI group showed that, at 5 years, autologous vein grafts had better long-term patency rates than PTFE and HePTFE grafts. At 5 years, the primary and secondary patency rate for autologous vein grafts were 63.2% (P= 0.324) and 83.2% (P = 0.020), respectively. Freedom from MALE was 72.0% with the use of autologous vein grafts, 47.9% using PTFE and, 52.9% using HePTFE, respectively (P= 0.021). CONCLUSIONS: Our study shows that femoropopliteal bypass surgery in patients with TASC D lesions is safe and effective in the long term. Autologous vein grafts remain the first choice for patients with CLTI, also for bypasses in AK position. However, prosthetic grafts in AK the position are an acceptable alternative for revascularisation when the saphenous vein is not available.

Early Graft, Limb and Mortality Outcomes from the Omniflow II Bio-Synthetic Graft.

BACKGROUND: Omniflow II biosynthetic grafts are a commonly used alternative to autologous grafts in vascular bypass procedures. They are chosen for their purported resilience to infection, often in instances of existing graft failure or infection. We examined the short term, 1-3 year outcomes of Omniflow grafts in terms of patency, limb survival and mortality in a sample of 24 individuals. METHODS: This is a single centred retrospective study of Omniflow II grafts implanted between September 23, 2015 and April 05, 2018 in our department. It includes grafts in all anatomical locations. Primary outcome measures were overall patient survival and time to this, primary graft patency (patency with no intervention) and then limb survival at 1 and 3 years. Kaplan-Meier survival analysis was plotted for the 3 primary outcome measures. RESULTS: A total of 24 grafts from 24 individuals were included with mean age 71.4 ± 11.7. We included 5 female and 19 male patients. The commonest indication was rest pain/claudication (N = 8) followed by graft occlusion (N = 6). Femoro-popliteal bypass (N = 13) and Femoro-distal bypass (N = 5) were the commonest procedures. Kaplan-Meier survival analysis demonstrated that 1 and 3-year primary patency rates were 54.2% and 37.5% respectively with Limb survival probability of 75% at 1 year and 70.8% at 3 years. These rates were all considerably lower than those found in previous comparative studies. Mortality however, compared favourably with 1 and 3-year survival probability 91.7% and 87.5% on average 296 days (range 95-451 days) after graft implantation. CONCLUSIONS: We found that rates of primary patency and limb salvage for this graft type were markedly lower than in comparable studies. Further work in the form of a RCT is indicated.

Medical Adjuvant Therapy in Reducing Thrombosis With Arteriovenous Grafts and Fistulae Use: A Meta-Analysis of Randomized Controlled Trials.

Hemodialysis is required for patients with end-stage renal disease (ESRD) that require arteriovenous (AV) grafts or fistulas for vascular access. These access points are prone to thrombosis. To determine the effect of medical adjuvant therapy on AV graft/fistula patency among patients with ESRD on hemodialysis. Adhering to the PRISMA 2020 statement, a systematic search was conducted until August 20, 2021, with keywords including arteriovenous graft, fistula, patency, thrombosis, hemodialysis, adjuvant treatment. The following databases were searched: PubMed, Scopus, Web of Science, CINAHL Plus, and Cochrane. A random-effects model was employed using Review Manager 5.4 for data analysis. The meta-analysis pooled in 1985 participants with 1000 (50.4%) in the medical adjuvant treatment group. At a snapshot, medical adjuvant therapy reduced the risk for graft thrombosis (RR = 0.64, P = .02). Notable medications included aspirin for graft thrombosis (RR = 0.36, P = .006) and ticlopidine for fistula thrombosis (RR = 0.53, P = .01). Certain antiplatelet therapies (aspirin and ticlopidine) reduced the number of patients with AV fistula/graft thrombosis among patients with high heterogeneity among the trials. Other therapies (fish oil, sulfinpyrazone, clopidogrel, and aspirin/dipyridamole) did not demonstrate significant improvement but may be promising once concrete evidence is available. Potential benefits of anti-platelet therapies may be explored to maintain the potency of AV grafts/fistulas through well-designed placebo-controlled trials and long-term follow-up.

Editor's Choice - Paclitaxel Coated Balloon Angioplasty vs. Plain Balloon Angioplasty for Haemodialysis Arteriovenous Access Stenosis: A Systematic Review and a Time to Event Meta-Analysis of Randomised Controlled Trials.

OBJECTIVE: A systematic review and meta-analysis of randomised controlled trials (RCTs) was performed to determine the effectiveness and safety of drug coated balloon (DCB) angioplasty compared with uncoated plain balloon (PB) angioplasty in treating arteriovenous access stenosis. METHODS: MEDLINE, Embase, Scopus, and the Cochrane Central Register of Controlled Trials were searched for RCTs comparing paclitaxel coated DCB and PB angioplasty for arteriovenous access stenosis. The last date of the literature search was 31 December 2020. Risk of bias of the retrieved studies was assessed with the Cochrane Collaboration tool for assessing risk of bias (RoB 2.0). The random effects model was used to estimate the risk of loss of target lesion patency (six and 12 months) and circuit patency (six and 12 months). Procedure related adverse events and mortality rate were also compared. Patency results were pooled using the time to event meta-analytical method and the quality of evidence was assessed according to the GRADE approach. RESULTS: Sixteen eligible trials, including 1 682 lesions, were included in the quantitative analysis for the efficacy and safety of paclitaxel coated DCBs. DCBs were associated with a lower risk of loss of target lesion patency at six months (HR 0.53, 95% CI 0.42 - 0.66) and 12 months (HR 0.60, 95% CI 0.47 - 0.76), and were also associated with improved six and 12 month circuit patency. Overall quality of evidence was moderate to low. Procedural complications were rare, and the risk of death up to 12 months was similar between the two groups (OR 1.03, 95% CI 0.68 - 1.56). CONCLUSION: Paclitaxel coated DCBs reduced the risk of loss of target lesion patency and circuit patency in arteriovenous access stenosis compared with PBs. Considering the heterogeneity of the included trials, there is a need to investigate optimal treatment regimens regarding drug dose and agent of the DCB and the treatment procedure.

Efficacy and Safety of Jotec E-Ventus BX Stent Graft for Iliac Branch Device Procedure: A Retrospective Clinical Study.

BACKGROUND: The endovascular aneurysm repair (EVAR) is a successful treatment for aorto-iliac aneurysms. The success of EVAR is enhanced by the use of devices that maintain the patency of targeted arteries namely the iliac branch device (IBD) With this study we aimed to evaluate the association between the use of Jotec E-ventus during EVAR with IBD and prognosis in patients with aorto-iliac aneurysms. METHODS: This is a retrospective, multicentric study enrolling patients referred to our Vascular Surgery Units from January 2015 to January 2020. All patients underwent EVAR with IBD using Jotec E-ventus as bridging stent. Primary endpoint was the development of types I and III endoleaks. Secondary endpoint was the onset of device occlusion with loss of vascular patency. RESULTS: We studied 32 patients (mean age 71.7±4.5y). Of these, 25 patients were treated with standard EVAR procedure whereas 7 were treated with isolated IBD due to extension of disease involving iliac bifurcation. Median follow-up lasted 15[IQR11-27] months. During follow-up, incidence rates for endoleaks and occlusion were 3.98(95%CI 0.48-14.41) and 1.99(95%CI 0.05-11.12) per 100 pts/year. CONCLUSIONS: Jotec E-ventus during EVAR is associated with a low rate of severe complications in a small cohort of patients with aorto-iliac aneurysms.

Acroangiodermatitis of the hand secondary to a dysfunctional arteriovenous fistula.

Acroangiodermatitis (AAD) is often seen in association with various vascular anomalies such as venous insufficiency, vascular syndromes, and conditions associated with thrombosis. This is the first case reported in the literature associated with arteriovenous fistula stenosis in a patient with chronic kidney disease on hemodialysis. This case is being described for its rarity and to familiarize the clinicians with this unusual complication, especially, to prevent them from thinking of this condition as an infectious complication. It is essential to recognize the uniqueness of the pathophysiology of this disease and to do a clear distinction with that of a venous ulcer. With this work we also aim to help health practitioners with proper management of the condition. As we've seen, surgical treatment in appropriately selected cases corrects the reflux of the venous system and successfully improves the appearance of the verrucous lesion. Our patient was successfully treated by correcting the arteriovenous fistula stenosis with near-complete subsidence of the verrucous lesion within days of the procedure. Acroangiodermatitis management must be conducted with a multidisciplinary approach (dermatology, vascular surgery, and internal medicine). It is essential the comprehensive management of these patients, to ensure prompt recovery and avoid chronic effects, as well as to guarantee the quality of life in the future.

Long-term outcome in pediatric surgical bypass grafting after traumatic injury and tumor resection: retrospective cohort analysis.

Vascular bypass surgery in children differs significantly from adults. It is a rarely performed procedure in the setting of trauma and tumor surgery. Besides technical challenges to reconstruct the small and spastic vessels, another concern in bypass grafting is the adequate limb length growth over time. The primary aim of this study was to assess long-term outcome after pediatric bypass grafting, in a single academic center, focusing on potential effects on limb development. In this retrospective cohort analyses we included all pediatric patients undergoing vascular bypass grafting at our department between 2002 and 2017. All patients ≤ 18 years suffered a traumatic injury or underwent a tumor resection of the lower or upper limb. The youngest female patient was 0.4 years, the youngest male patient was 3.5 years. During the observation period, 33 pediatric patients underwent vascular repair, whereby 15 patients underwent bypass grafting. Median overall follow-up was 4.7 years (IQR ± 9). 8 patients (53%) had a traumatic injury (traumatic surgery group) and 7 patients had a planned orthopedic tumor resection (orthopedic surgery group). In 13/15 (87%) a great saphenous vein (GSV) graft and in 2/15 (13%) a Gore-Tex graft was used for bypassing. Both Gore-Tex grafts showed complete occlusion 12 and 16 years after implantation. No patient died in the early postoperative phase (< 30 days), however 3/7 (43%) in the orthopedic group died during follow-up. Revision surgery had to be performed in 1/15 (7%) patients. A functional use of the extremity was reported in all patients. Normal limb length growth according to the contralateral site, and therefore bypass growth, could be documented in 14/15 patients. Children are surgically challenging. In our study, surgery by a specialized vascular surgery team using GSV grafts led to adequate limb length and bypass growth, and we observed no functional restrictions.

Drug Coated Balloons for Dysfunctional Haemodialysis Venous Access: A Patient Level Meta-Analysis of Randomised Controlled Trials.

OBJECTIVE: To perform an individual patient data level meta-analysis of randomised controlled trials comparing drug coated balloon angioplasty (DCB) against conventional percutaneous transluminal angioplasty (PTA) in the treatment of dysfunctional haemodialysis venous access. METHODS: A search was conducted from inception to 13 November 2020. Kaplan-Meier curves comparing DCB with PTA by target lesion primary patency (TLPP) and access circuit primary patency (ACPP) were graphically reconstructed to retrieve patient level data. One stage meta-analyses with Cox models with random effects shared frailties were conducted to determine hazard ratios (HRs). Dynamic restricted mean survival times (RMST) were conducted in view of violation of the proportional hazards assumption. Conventional two stage meta-analyses and network meta-analyses under random effects Frequentist models were conducted to determine overall and comparative outcomes of paclitaxel concentrations used. Where outliers were consistently detected through outlier and influence analyses, sensitivity analyses excluding those studies were conducted. RESULTS: Among 10 RCTs (1 207 patients), HRs across all models favoured DCB (one stage shared frailty HR 0.62, 95% CI 0.53 - 0.73, p < .001; two stage random effects HR 0.60, 95% CI 0.42 - 0.86, p = .018, I2 = 65%) for TLPP. Evidence of time varying effects (p = .005) was found. TLPP RMST was + 3.54 months (25.0%) longer in DCB treated patients compared with PTA (p = .001) at three years. TLPP at six months, one year, and two years was 75.3% vs. 58.1%, 51.1% vs. 37.1%, and 31.4% vs. 26.0% for DCB and PTA, respectively. The P-Scores within the Frequentist network meta-analysis suggest that higher concentrations of paclitaxel were associated with better TLPP and ACPP. Among six RCTs (854 patients), the one stage model favoured DCB (shared frailty HR 0.72, 95% CI 0.60 - 0.87, p < .001) for ACPP. Conversely, the two stage random effects model demonstrated no significant difference (HR 0.76, 95% CI 0.35 - 1.67, p = .41, I2 = 81%). Sensitivity analysis excluding outliers significantly favoured DCB (HR 0.61, 95% CI 0.41 - 0.91, p = .027, I2 = 62%). CONCLUSION: Overall evidence suggests that DCB is favoured over PTA in TLPP and ACPP.

Arteriovenous fistula maturation: Physical exam versus flow study.

PURPOSE: The purpose of this study was to determine the utility of routine duplex flow study 4 to 6 weeks after primary AVF creation and to compare physical exam against a duplex flow study in predicting fistula maturation. A surveillance algorithm was established to evaluate the naïve fistula after primary creation. METHODS: This was a single institution retrospective review of 155 veterans with primary autogenous AVF creation from 2016 to 2018. All patients received a duplex flow study evaluation after primary creation. A comparison was made between physical exam (PE) and flow study at 4 to 6 weeks post creation. Sensitivities and specificities of physical exam and duplex flow study were compared head-to-head in predicting unassisted fistula maturation. A mature AVF was defined as a fistula that could be repetitively cannulated and provided adequate flow for dialysis. Failure of maturation was defined as an AVF that was never usable for dialysis. An abnormal duplex included thrombosis, stenosis (> 50% on gray scale imaging), inadequate vein diameter (< 4 mm), inadequate vein length or superficialization, or poor flow (< 500 ml/min). Bivariate comparisons were conducted using Pearson's χ², Fishers exact test, and Wilcoxon test depending on distribution. Significance was defined as P < 0.05. RESULTS: There were 53 patients with radiocephalic (RC) fistulas, 41 patients with brachiocephalic (BC) fistulas, and 6 patients with brachiobasilic (BB) fistulas. Of patients with a confirmed abnormal duplex ultrasound, 53% had an abnormal PE (sensitivity 53%; PPV 96.3%, P < 0.001). Of the patients with a confirmed normal duplex, 98% had a normal PE (specificity 98%; NPV 68.5%, P < 0.001). An abnormal duplex flow study had a 67% sensitivity for predicting AVF failure or need for reintervention while an abnormal physical examination had a 42% sensitivity in predicting AVF failure or need for reintervention (P < 0.001). In total, 48 fistulas needed reintervention, however only 20 (42%) were associated with an abnormal physical examination. Of those 48 reinterventions, 20 (42%) fistulas exhibited primary assisted maturation (P < 0.001). On duplex flow study alone, 32 patients had hemodynamically significant lesions necessitating reintervention, which went on to afford 9 (28%) primary assisted mature fistulas (P = 0.69). CONCLUSION: Abnormal duplex flow studies have a better sensitivity for detecting AVF failure or the need for reintervention compared to physical exam alone. An abnormal duplex correlates more with needing a reintervention to achieve maturation than physical exam. Therefore, we advocate routine use of a postoperative duplex flow study to identify potentially correctable issues and optimize fistula maturation.

Limb Graft Occlusion Following Endovascular Aneurysm Repair for Infrarenal Abdominal Aortic Aneurysm with the Zenith Alpha, Excluder, and Endurant Devices: a Multicentre Cohort Study.

OBJECTIVE: Limb graft occlusion (LGO) is a serious complication after endovascular aneurysm repair (EVAR) and while device development enables treatment of increasingly complex aortic anatomy, little is known about how endograft type affects the risk of occlusion. This observational study aimed to explore the incidence of LGO after EVAR for three major endograft systems. METHODS: All patients with standard EVAR as the primary intervention for infrarenal abdominal aortic aneurysm (AAA), between January 2012 and December 2018, at five Swedish vascular surgery centres, were included in this multicentre retrospective cohort study. LGO was defined as a total limb occlusion regardless of symptoms, or a treated significant stenosis. A nested case control (NCC) design with incidence density sampling of 1:3 was used for analysis of potential per-operative and morphological risk factors. Conditional logistic regression was used to estimate multivariable odds ratios (OR) with 95% confidence intervals (CI) RESULTS: A total of 924 patients were included. The majority were male (84%), the mean age was 76 years (± 7.5 SD), and median AAA diameter was 59 mm (IQR 55, 67). Patients were treated with Zenith Alpha (n = 315, ZISL limbs), Excluder (n = 152, PLC/PXC limbs), and Endurant (n = 457, ETLW/ ETEW limbs). During median follow up of 37 months (IQR 21, 62), 55 occlusions occurred (5.9%); 39 with Zenith Alpha (12.4%), one with Excluder (0.7%), and 15 with Endurant (3.3%). In the NCC analysis, the Zenith Alpha device (OR 5.31, 95% CI 1.97 - 14.3), external iliac artery (EIA) landing (OR 5.91, 95% CI 1.30 - 26.7), and EIA diameter < 10 mm (OR 4.99, 95% CI 1.46 - 16.9) were associated with an increased risk of LGO. CONCLUSION: Endograft device type is an independent risk factor for LGO after EVAR. Specifically, the Zenith Alpha demonstrated an increased risk of LGO compared with the Endurant and Excluder devices. In addition, a narrow EIA and landing zone in EIA are also risk factors for LGO.

Mechanisms, Prevention and Treatment of Saphenous Vein Graft Disease.

Saphenous vein grafts are imperfect yet indispensable conduits commonly used for coronary artery bypass grafting. Their degeneration ultimately leading to occlusion results from the pathological response of the vein to altered blood rheology and several types of vascular injury. Surgical techniques minimizing vessel damage, and prolonged antiplatelet and lipid-lowering treatment are established methods of mitigating the degeneration process hence preventing graft occlusions. Percutaneous interventions in degenerated vein grafts carry high risk of embolization, periprocedural myocardial infarction and restenosis. Thus, native vessel should be the preferred treatment target in case of graft failure whenever technically feasible.

Adjuvant heparinization before manipulation of artery reduces early failure in primary arteriovenous fistula for end-stage renal disease patients.

BACKGROUND: Arteriovenous fistula (AVF) is the most preferred vascular access for hemodialysis patients, and early failure of AVF is one of the most avoidable complications of this procedure. We retrospectively evaluated whether adjuvant systemic heparinization just before arterial manipulation could reduce early failure of primary AVF. METHODS: Three hundred and fifty-six patients with end-stage renal failure who underwent primary AVF surgery from April 2009 to September 2020 were enrolled in this study. The patients were divided into two groups based on whether they received adjuvant heparinization or not. Patient backgrounds, frequency of early AVF failure, and bleeding events were compared between the two groups. Multivariate Cox regression analysis identified risk factors for early AVF failure. RESULTS: Early failure of AVF was observed in only 2 of 157 patients (1.2%) in the adjuvant group, and the incident was significantly lower than observed in the non-adjuvant group, i.e., 17 of 199 patients (8.5%) (p = 0.002). Bleeding events were not significantly different between the two groups. Seven of 157 patients (4.5%) in the adjuvant group and 7 of 199 patients (3.5%) in the non-adjuvant group experienced bleeding events (p = 0.785). Female sex, use of steroids, hypoalbuminemia, venous stenosis in pre-surgical evaluation, arterial spasm in the perioperative period, new-onset venous stenosis after AVF anastomosis, technical failure of surgery, no early cannulation after surgery, and non-adjuvant heparinization were related to early AVF failure in the multivariate regression analysis. CONCLUSION: Adjuvant systemic heparinization therapy just before arterial manipulation reduced early failure of primary AVF without increasing bleeding events.