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Purpose: Duplex ultrasound (DUS)-measured peak systolic velocity ratios (PSVRs) are commonly used to evaluate arterial stenosis in lower extremity artery disease (LEAD). However, these measurement methods have not yet been standardized. This study aimed to reveal the influence of measuring methods on PSVR values., Methods: A 132 femoropopliteal lesions with PSVR ranging from 1.5 to 3.5 evaluated using method A (angle correction 60°, the direction of blood flow, the no or few atherosclerotic changes closest to the lesion proximal side was defined as the nonstenotic area) were included. The following 4 different methods were then compared with method A: method B, angle correction 45°; method C, angle correction 60° measured along the vessel wall; D, angle correction 60°, with the nonstenotic area the lowest peak systolic velocity area; and E, angle correction 60°, with the reference point fixed at 2 cm proximal to the target lesion area. The difference in PSVR values was analyzed using the Bland-Altman method., Results: The mean PSVR value measured by method A was 2.27±0.51, those measured by methods B, C, D, and E were 2.21±0.55, 2.31±0.66, 2.34±0.63, and 2.11±0.63, respectively. The 95% prediction intervals of the differences in PSVR measurements versus A were -0.64 to +0.53 for method B, -0.59 to +0.68 for method C, -0.77 to +0.91 for method D, and -1.12 to +0.79 for method E., Conclusion: PSVR values considerably differed between measuring methods. PSVR values by DUS are largely dependent on the measurement methods, which could considerably affect the judgment of LEAD., Clinical Impact: Due to differences in several DUS measurement methods, the PSVR results could be changed. Therefore, to need further investigations and unification of measurement method., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objectives: Residual dissection is a concern in endovascular treatment with a DCB, and there is limited knowledge of hemodynamics at a dissection lesion. Therefore, the objective of this study is to evaluate the mean pressure gradient (MPG) and fractional flow reserve (FFR) at a residual dissection after DCB angioplasty for the superficial femoral artery (SFA)., Methods: A total of 59 cases with residual SFA dissection treated with DCB angioplasty at a single center were analyzed retrospectively. The dissection was classified into 6 types (A-F). The primary endpoints were MPG and FFR at a residual dissection lesion after DCB angioplasty, using evaluation with a pressure wire., Results: The median lesion length was 70 (40-130) mm with 24% popliteal involvement, and 11 cases (18%) had chronic total occlusion. A completion angiogram revealed dissection of types A (n = 33, 56%), B (n = 18, 31%), C (n = 7, 12%), and D (n = 1, 2%). The median MPGs in type A, B, and C cases were 0 (0-2), 0 (0-4), and 3 (0-6) mmHg, with a significant lower in type C cases than in type A cases (A vs C, P = .021). The median FFRs in type A, B, and C cases of 1.0 (.98-1.00), 1.0 (.96-1.00), and .98 (.95-1.00) did not differ significantly among dissection types (A vs B, P = .86; A vs C, P = .055; B vs C, P = .15)., Conclusions: This is the first report of hemodynamics at a SFA dissection. The results suggest that low-grade dissection (types A or B) does not affect MPG and FFR at a SFA lesion. This indicates that a bailout stent may be unnecessary for patients with dissection of types A or B. A further investigation is needed to determine whether a scaffold is required for a SFA lesion with type C dissection., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: It is assumed that identification and correction of asymptomatic stenoses in the vascular access circuit will prevent thrombosis that would require urgent intervention to continue hemodialysis treatment. However, the evidence base for this assumption is limited. Recent international clinical practice guidelines reach different conclusions on the use of surveillance for vascular access flow dysfunction and recommend further research to inform clinical practice., Methods: The FLOW trial is a double-blind, multicenter, randomized controlled trial with a 1:1 individual participant treatment allocation ratio over two study arms. In the intervention group, only symptomatic vascular access stenoses detected by clinical monitoring are treated, whereas in the comparison group asymptomatic stenoses detected by surveillance using monthly dilution flow measurements are treated as well. Hemodialysis patients with a functional arteriovenous vascular access are enrolled. The primary outcome is the access-related intervention rate that will be analyzed using a general linear model with Poisson distribution. Secondary outcomes include patient satisfaction, access-related serious adverse events, and quality of the surveillance process. A cost effectiveness analysis and budget impact analysis will also be conducted. The study requires 828 patient-years of follow-up in 417 participants to detect a difference of 0.25 access-related interventions per year between study groups., Discussion: As one of the largest randomized controlled trials assessing the clinical impact of vascular access surveillance using a strong double-blinded study design, we believe the FLOW trial will provide much-needed evidence to improve vascular access care for hemodialysis patients., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: The superficial radial artery (SRA) is a rare congenital anomaly in the forearm. However, it can be detected incidentally via trauma, intraoperative findings, angiography, or ultrasonography. In addition, intra-arterial infusion of intravenous medications and difficulties in radial artery catheterization may occur in cases of the SRA., Methods: Between December 2016 and July 2020, anomalous branches of radial arteries were found incidentally in nine patients at the preoperative visit and identified during ultrasound-guided radial artery puncture in 21 patients when radial artery catheterization using the palpation method proved difficult. Ultrasound examinations were performed for diagnosis and evaluation of these 30 patients., Results: All anomalous branches of the radial artery were SRAs; 11 (37%), 13 (43%), 6 (20%) were present on the right side, on the left side, and bilaterally, respectively. All SRAs ran close to the cephalic vein. The vascular diameters of the radial arteries were the smallest in the radial artery distal to the SRA bifurcation (followed by in the SRA) and the largest in the radial artery proximal to the bifurcation ( p < .001). In two cases, color Doppler study revealed that both the blood flow and color Doppler signal of the SRA disappeared with compression of the radial artery proximal to the SRA bifurcation., Conclusions: Because the SRA runs very close to the cephalic vein, a tourniquet applied to the arm may easily lead to intravenous catheter misplacement into the SRA. In addition, the small radial artery distal to the SRA bifurcation causes difficulty in radial artery catheterization. Furthermore, SRA cases may have falsely normal Allen's test results. Therefore, the authors recommend that the SRA must be identified before vascular puncture for safe vascular catheterization in the forearm., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Although arteriovenous fistula (AVF) continues to be the vascular access of choice for the hemodialysis, arteriovenous graft (AVG) can be the best choice in certain categories of patients and could have several advantages over AVF in a "patient centered approach" to vascular access. In the clinical management of prosthetic fistulas, color Doppler ultrasound (CDU) is the imaging method of choice for identifying stenosis and other AVG complications. In this review, besides highlighting the pivotal role of CDU in the diagnosis of AVG complications, we will underline the key role that ultrasound can play in identifying those stenosis most likely to cause AVG thrombosis. Furthermore, we will emphasize the support that CDU can play in distinguishing the different types of grafts and prosthetic devices such as stent-grafts, in identifying AVG with lower survival, CDU utilities and limitations in the evaluation of freshly-implanted grafts, the different sites available for AVG volume flow measurement and their use based on the configuration of the prosthesis, the time interval elapsed from the surgical intervention and the integrity of the prosthetic walls., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: To date, PCSK9 inhibitors are well known for eliminating cardiac and cerebral artery ischemia events by lowering the serum lipid level. However, the pathophysiological value of in-plaque PCSK9 expression is still unclear., Methods: Advanced plaques removed by carotid endarterectomy were sectioned and stained to identify the PCSK9 expression pattern and its co-expression with rupture-relevant markers. To investigate the correlation of PCSK9 expression with regional blood shear flow, hemodynamic characteristics were analyzed using computational fluid dynamics, and representative parameters were compared between PCSK9 positive and negative staining plaques. To explore this phenomenon in vitro, human aortic vascular smooth muscle cells were used to overexpress and knock down PCSK9. The impacts of PCSK9 modulations on mechanical sensor activity were testified by western blot and immunofluorescence. Real-time polymerase chain reaction was used to evaluate the transcription levels of downstream rupture-prone effectors., Results: PCSK9 distribution in plaque preferred cap and shoulder regions, residing predominantly in smooth muscle actin-positive cells. Cap PCSK9 expression correlated with fibrous cap thickness negatively and co-expressed with MMP-9, both pointing to the direction of plaque rupture. A hemodynamic profile indicated a rupture-prone feature of cap PCSK9 expression. In vitro, overexpression and knockdown of PCSK9 in human aortic vascular smooth muscle cells has positive modulation on mechanical sensor Yes-associated protein 1 (YAP) activity and transcription levels of its downstream rupture-prone effectors. Serial section staining verified in situ colocalization among PCSK9, YAP, and downstream effectors., Conclusions: Cap PCSK9 possesses a biomarker for rupture risk, and its modulation may lead to a novel biomechanical angle for plaque interventions., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: To identify the effects of patient risk factors and pelvic venous reflux (PVR) patterns on treatment outcomes of Pelvic Vein Embolisation (PVE) for Pelvic Venous Disorder (PeVD)., Methods: We performed a retrospective cohort review assessing population, intervention, comparison, and outcomes (PICO) for women undergoing PVE for PVR January 2017-January 2021. We identified 190 patients who had completed both questionnaires and who had given consent for their information to be used for research (Median age 46, IQR 40-52). The distribution of pathological pelvic venous reflux found on transvaginal duplex ultrasound (TVDUS) was analysed for all patients. Pre- and post-procedure symptom burden scores were studied using a standardised questionnaire protocol. We used inferential univariate non-parametric statistics to describe our data., Results: 190 cases were reviewed; 62.6% (119/190) premenopausal, 11.1% (21/190) perimenopausal, 25.3% (48/190) postmenopausal and menopausal status not documented 1% (2/190). 10.1% (19/188) were nulliparous (average age 34 years; range 20-55 years). There was a statistically significant improvement in all symptoms and in the appearance of varicosities on TVDUS post-PVE ( P < 0.05) of the ovarian vein plexus, uterus plexus, arcuate veins, vaginal wall, peri-urethral, peri-anal, haemorrhoids, labial and proximal thigh. The locations of veins requiring embolisation having demonstrated reflux were analysed; 82.8% (154/186) underwent embolisation of at least one internal iliac vein tributary and ovarian vein embolisation. Age, parity, menopausal status and previous laparoscopy did not affect symptom improvement ( P > 0.05). No significant complications such as coil migration were observed., Conclusions: PVE is an effective treatment for pelvic pain due to PeVD and its diagnosis should not be limited to multiparous women of childbearing age, as a significant proportion of patients who benefited from PVE were either nulliparous and/or postmenopausal., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Contemporary quality control methods are often insufficient in predicting clinical outcomes after revascularization in lower extremity arterial disease (LEAD) patients. This study evaluates the potential of near-infrared fluorescence imaging with indocyanine green to predict the clinical outcome following revascularization. Near-infrared fluorescence imaging was performed before and within 5 days following the revascularization procedure. Clinical improvement was defined as substantial improvement of pain free walking distance, reduction of rest- and/or nocturnal pain, or tendency toward wound healing. Time-intensity curves and 8 perfusion parameters were extracted from the dorsum of the treated foot. The quantified postinterventional perfusion improvement was compared within the clinical outcome groups. Successful near-infrared fluorescence imaging was performed in 72 patients (76 limbs, 52.6% claudication, 47.4% chronic limb-threatening ischemia) including 40 endovascular- and 36 surgical/hybrid revascularizations. Clinical improvement was observed in 61 patients. All perfusion parameters showed a significant postinterventional difference in the clinical improvement group ( P -values <.001), while no significant differences were seen in the group without clinical improvement ( P -values .168-.929). Four parameters demonstrated significant differences in percentage improvement comparing the outcome groups ( P -values within .002-.006). Near-infrared fluorescence imaging has promising additional value besides clinical parameters for predicting the clinical outcome of revascularized LEAD patients., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Negative remodeling of the distal aorta due to residual dissection significantly impacts the long-term outcomes of dissection patients after proximal repair of acute aortic dissection. Branched/fenestrated aortic stents are technically demanding, and studies of the first generation of multilayer flow modulators for tackling this clinical scenario are few and limited. The single-center results from a multicenter, prospective, and randomized controlled study aimed to verify the safety and effectiveness of a newly-designed flowdynamics dense mesh stent for treating residual dissection after proximal repair., Methods: Patients with nonchronic residual dissection involving visceral branches were prospectively enrolled in 3 centers (ChiCTR1900023638). Eligible patients were randomly assigned to the flowdynamics dense mesh stent (FDMS) group and control group. Follow-up visits were arranged at 1, 3, 6, and 12 months after recruitment. The primary endpoints were all-cause and aortic-related mortality. The secondary endpoints included visceral branch occlusion, reintervention, and severe adverse events. Morphological changes were analyzed to exhibit the therapeutic effect. Our center participated in the multicenter prospective randomized controlled trial, and the preliminary single-center experience was reported., Results: Thirty-six patients were enrolled in our center, and the baseline characteristics of the 2 groups were comparable. Thirty-four patients completed the 12 month follow-up. Freedom from all-cause and aortic-related death were 94.4% and 100%. All visceral branches remained patent in the FDMS group. Increased area of the true lumen (1.03±0.38 vs 0.48±0.63 cm 2 at the plane below renal arteries, p=0.006; 1.27±0.80 vs 0.32±0.50 cm 2 at the plane 5 cm below renal arteries, p<0.001) and decreased area of the false lumen at the plane below renal arteries (-1.03±0.84 vs -0.15±1.21 cm 2 , p=0.023) were observed in the FDMS group compared with those parameters in the control group. The FDMS group showed a significant increase in true lumen volume (p<0.001) and a significant decrease in false lumen volume (p=0.018)., Conclusions: This newly-designed FDMS for endovascular repair of residual dissection after the proximal repair is safe and effective at 12 months., Clinical Impact: One-year results of the randomized controlled clinical trial indicated the short-term safety and promising effect of FDMS on treating non-chronic residual dissection after proximal repair. At the 12th-month follow-up, the true lumen expanded, the false lumen shrunk and all visceral arteries kept patent. As far as I'm concerned, this is the first randomized controlled study concerning utilizing multilayer flow mesh stent treating aortic dissection. Despite a preliminary single-center report, our results are supposed to provide high-quality evidence to guide clinical practice and fill the gap in the application of FDMS., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: The study is supported by Shanghai Qigong Medical Technology Co., Ltd (Shanghai, China). All authors have nothing else to disclose regarding commercial support.

Cardiac myxomas are the most common primary benign tumors of the heart. The occlusion of peripheral arteries and complete obstruction of the abdominal aorta by a tumor embolus presents with distinct clinical manifestations. Herein, we present the case of a 38-year-old male with acute paresthesia, muscle weakness, erythematous, and violaceous changes in skin color localized to the dorsum of the left forefoot initially treated as cutaneous vasculitis. Further studies revealed the total occlusion of the terminal abdominal aorta by a saddle embolus from a cardiac myxoma. A multidisciplinary team consisting of cardiothoracic and vascular surgeons were involved in treating the patient, which resulted in full resolution of the case. This paper details the progression of acute bilateral limb ischemia to chronic limb threatening ischemia resulting from the total occlusion of the terminal abdominal aorta by a saddle embolus., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Long-term indwelling central venous catheters (CVCs) may cause complications, such as central venous disease (CVD). CVD eliminates the possibility of establishing new arteriovenous access. We herein describe a case in which an arteriovenous graft (AVG) is implanted through the peripheral veins and blood flows back to the patent azygos vein, secondary to superior vena cava stenosis. This shows that if the CVD is correctable or the collateral circulation is an alternative vascular pathway that allows blood to return back to the right atrium, the internal fistula flow is well-balanced with the collateral circulation and there are no clinical symptoms of CVD, an arteriovenous access can be established for the operation. This provides a viable, long-term vascular access option for hemodialysis patients with central venous resource depletion., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The arteriovenous fistula (AVF) is the preferred venous access for maintenance haemodialysis. AVF dysfunction can progress to access failure, with all the associated morbidity and costs of revising vascular accesses. Routine surveillance of AVFs using specialised equipment has the potential to enable early detection of potential problems. The KDOQI Clinical Practice Guidelines for Vascular Access: Update 2019 suggest that surveillance may be useful to supplement regular clinical monitoring but acknowledge a lack of evidence to make firm recommendations. This scoping review of peer-reviewed literature explored outcomes with the routine surveillance of AVFs using specialised equipment in haemodialysis dependent adults. A systematic search was undertaken using terms such as 'vascular access', haemodialysis, surveillance and 'access flow', utilising the data bases ProQuest (Medline), CINAHL and Embase to include original research articles published between October 2016 and August 2022. A total of eight papers were identified for comprehensive analysis, including two randomised controlled trials, two cross-sectional studies, two retrospective reviews and two evaluations. Themes identified include the incidence of thrombotic events, the role of access blood flow measurements, the need for follow-up angiograms after surveillance and identification of the at-risk access. This review of research published in recent years demonstrated an ongoing paucity of evidence for the benefits of routine AVF surveillance. More research focused on actual outcomes is needed in this important area that is a routine part of dialysis unit workloads everywhere., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Arteriovenous Fistula (AVF) surveillance is required to detect early dysfunction (thrombosis, stenosis) and its timely correction prolongs access-patency. Clinical examination (CE) and doppler have been used as screening/surveillance of AVF, for early detection of AVF dysfunction. Since there was inadequate evidence for KDOQI to make recommendations on AVF surveillance and on secondary failure rate. We compared CE, doppler and fistulogram as surveillance modalities in detecting a secondary failure in matured AVF., Methodology: This prospective-observational, single-center study, was done between December 2019-April 2021. CKD stage 5 patients on dialysis/Not-on-dialysis with matured AVF were included at third month. CE, doppler (blood flow, vein diameter, depth), and fistulogram were done at third and sixth month. Secondary failure was assessed at sixth month classifying AVF to patent/functional and failed group. Diagnostic tests were performed by comparing three methods considering fistulogram as gold-standard. Residual urine output is also monitored to look for any contrast induced residual renal function loss., Results: Of total 407 created AVF, 98 (24%) had primary failure. Twenty-five (6%) had surgical complications including unsuccessful AVF and aneurysm/rupture, 156 lost follow-up at third month, 104 consented patients were enrolled, 16 lost to follow-up subsequently, and 88 patients' data were analyzed at the end. At the sixth month, 76(86.4%) had patent AVF, 8 (9.1%) had secondary failure (Thrombosis-4, Central Venous Stenosis-4), and 4 (4.1%) patients expired. Considering fistulogram as a diagnostic standard, CE showed 87.5% sensitivity, and 93.4% specificity (cohen's kappa value of 0.66). Doppler had sensitivity and specificity of 87% and 96% respectively (cohen's kappa value of 0.75), Combination of clinical examination with doppler showed sensitivity and specificity of 100% and 89% respectively., Conclusion: Although the secondary AVF failure rate is less than the primary, CE is an important and valuable tool in the diagnosis and surveillance of AVF in detecting its dysfunction. Moreover, CE with doppler can be used as a surveillance protocol that can detect early AVF dysfunction at par with Fistulogram., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: The methods of estimating vascular access (VA) flow rates are usually based on the indicator dilution theory by measuring recirculation during dialysis sessions., Methods: This is an observational study comparing the VA flow rates measured by NIKKISO DBB-EXA™ and Transonic®. Sixty-five patients (38 M/27 F, mean age 72 ± 10 years) participated in the study. We measured the VA flow rates during dialysis twice with each method and repeated the procedure 7 days later., Results: In 130 double measurements for each method on the same day, mean flow with Transonic® was 1413±715 ml/min and with DBB-EXA™ 1297 ± 664 ml/min. In Bland-Altman analysis, the mean difference between the two methods was 159 ± 211 ml/min (limits of agreement: -274 and 572 ml/min). Eighty-one out of the 130 DBB-EXA™ measurements were within 25% of the Transonic® measurements (62% accuracy). Regarding reproducibility of each method on different days, mean difference in the Bland-Altman analysis was 29 ± 620 ml/min (limits of agreement: -1186 and 1244 ml/min) for the Transonic® measurements and 132 ± 625 ml/min (limits of agreement: -1092 and 1356 ml/min) for the DBB-EXA™ measurements. The measurements on two different days were within 25% of each other for 52 of the 65 patients (80%) with the Transonic® method, and for 35 of the 65 patients (54%) with the DBB-EXA™ method., Conclusions: In conclusion, the DBB-EXA™ method underestimates VA flow rates compared to the Transonic® technique, resulting in a limited accuracy of 62%. There was poor reproducibility for both methods in different day measurements with better performance of the Transonic® technique. The DBB-EXA™ method could be used as a simple tool for a rough estimate of VA flow rates but cannot replace the Transonic® reference method., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Arteriovenous fistulas (AVFs) are frequently used for hemodialysis access, but approximately 15%-20% of AVFs fail to mature within 3 months of their creation. Vascular access interventional therapy (VAIVT) is typically performed for treating an immature AVF. However, it should be performed 4-6 weeks or later after AVF creation. Here, we present a case in which VAIVT effectively addressed AVF occlusion that occurred only 9 days after its creation. The patient was an 82-year-old woman with chronic kidney disease who underwent surgery to create a left radiocephalic AVF for hemodialysis. Nine days postoperatively, disappearance of the AVF sound prompted an angiography, revealing thrombosis near the AVF anastomosis. VAIVT successfully restored blood flow, resulting in AVF maturation, and with no thrombosis or flow dysfunction at 21 months after VAIVT. To the best of our knowledge, this case presents the earliest successful intervention for an occluded AVF., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: Clinical guidelines provide recommendations on the minimal blood vessel diameters required for arteriovenous fistula creation but the evidence for these recommendations is limited. We compared vascular access outcomes of fistulas created in agreement with the ESVS Clinical Practice Guidelines (i.e. arteries and veins >2 mm for forearm fistulas and >3 mm for upper arm fistulas) with fistulas created outside these recommendations., Methods: The multicenter Shunt Simulation Study cohort contains 211 hemodialysis patients who received a first radiocephalic, brachiocephalic, or brachiobasilic fistula before publication of the ESVS Clinical Practice Guidelines. All patients had preoperative duplex ultrasound measurements according to a standardized protocol. Outcomes included duplex ultrasound findings at 6 weeks after surgery, vascular access function, and intervention rates until 1 year after surgery., Results: In 55% of patients, fistulas were created in agreement with the ESVS Clinical Practice Guidelines recommendations on minimal blood vessel diameters. Concordance with the guideline recommendations was more frequent for forearm fistulas than for upper arm fistulas (65% vs 46%, p  = 0.01). In the entire cohort, agreement with the guideline recommendations was not associated with an increased proportion of functional vascular accesses (70% vs 66% for fistulas created within and outside guideline recommendations, respectively; p  = 0.61) or with decreased access-related intervention rates (1.45 vs 1.68 per patient-year, p  = 0.20). In forearm fistulas, however, only 52% of arteriovenous fistulas created outside these recommendations developed into a timely functional vascular access., Conclusions: Whereas upper arm arteriovenous fistulas with preoperative blood vessel diameters <3 mm had similar vascular access function as fistulas created with larger blood vessels, forearm arteriovenous fistulas with preoperative blood vessel diameters <2 mm had poor clinical outcomes. These results support that clinical decision-making should be guided by an individual approach., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: Single bouts of prolonged bent-legged sitting attenuate popliteal endothelial-dependent vasodilation (as assessed via flow-mediated dilation [FMD]), which is partially attributed to arterial 'kinking'. However, the impact of knee-flexion angle on sitting-induced popliteal FMD is unknown. The objective of this study was to perform separate laboratory and free-living studies to test the hypotheses that: (1) popliteal FMD impairments would be graded between knee flexions at 90° (bent-legged sitting) > 45° > 0° (straight-legged sitting) following a 3-hour bout of sitting; and (2) more habitual time spent bent-legged sitting (< 45°) would be associated with lower FMD., Methods: The laboratory study included eight young, healthy adults (24 ± 2 years; four women) who underwent two sitting bouts over 2 days with one leg positioned at a knee-flexion angle of 0° or 90° and the opposite leg at 45° knee flexion. Popliteal FMD was assessed at pre- and postsitting timepoints., Results: Sitting-induced reductions in FMD were similar between all knee-flexion angles (all, p > 0.674). The free-living study included 35 young, healthy adults (23 ± 3 years; 16 women) who wore three activPAL monitors (torso, thigh, shin) to determine detailed sedentary postures. Time spent sedentary (624 ± 127 min/day), straight-legged sitting (112 ± 98 min/day), and bent-legged sitting (442 ± 106 min/day) were not related to relative FMD (5.3 ± 1.8%; all, p > 0.240)., Conclusion: These findings suggest that knee-flexion angle-mediated arterial 'kinking' during sitting is not a major contributor toward sitting-induced popliteal endothelial-dependent vasodilatory dysfunction., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: Effectiveness of thoracic endovascular aortic repair in type B aortic dissection is impaired by persistent retrograde false lumen flow via distal re-entry tears. Controlled, stentgraft-assisted balloon dilatation of the true lumen at its lower end, or Knickerbocker technique, may block retrograde false lumen flow and consequently improve effectiveness by inducing immediate thrombosis along the entire descending thoracic aorta., Materials and Methods: A single-center retrospective analysis was performed for all consecutive patients with aortic dissection treated with the Knickerbocker technique to block retrograde false lumen flow., Results: Eleven patients were included for analysis. Intraoperative control angiography showed successful occlusion of the false lumen at the level of balloon dilatation in 9 out of 11 patients (82%). There was one perioperative mortality (9%), due to stroke. There were 2 early reinterventions, due to retroperitoneal bleeding and due to chyle leakage in the neck after left subclavian artery bypass. Median clinical follow-up duration was 6 (interquartile range [IQR] 2-11] months. There were 2 deaths during follow-up, one at 2 months after TEVAR from unknown cause of death, and one after 11 months due to rupture of an ascending aortic pseudoaneurysm. The Knickerbocker technique led to positive aortic remodeling. At 3 months follow-up, 100% of patients showed complete false lumen thrombosis in the thoracic aorta proximal to the level of balloon dilatation, with decreasing false lumen diameters (100%) and stable (44%) or decreasing (56%) total aortic diameters. In most patients, the false lumen distal to the stentgraft (i.e. at visceral level) remained patent (11% false lumen thrombosis rate), leading to ≥2 mm dilatation at this level (78% of patients) and in the infrarenal abdominal aorta (56% of patients) at 3 months postoperatively. No distal stent-graft-induced new entry tears were noticed during follow-up., Conclusion: The Knickerbocker technique is feasible and effective, leading to positive aortic remodeling of the aorta covered by stentgraft in all of a small cohort of patients., Clinical Impact: Persistent, retrograde false lumen perfusion from distal re-entries following thoracic endovascular aortic repair (TEVAR) for Stanford type B aortic dissection, may lead to progressive, aneurysmal dilatation. Controlled, stent graft-assisted balloon dilatation of the true lumen in the distal descending aorta (i.e. Knickerbocker technique) during TEVAR effectively excludes the false lumen from persistent flow resulting in positive aortic remodeling in our small cohort of patients, and hence potentially eliminates the risk of late post-dissection aneurysm formation in the descending thoracic aorta., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: RHH declares consultancy fees by Medtronic and Terumo Aortic. The remaining authors declare no conflicts of interest. Some of the patients included in this study have been enrolled in the DISSECT-N registry sponsored by Medtronic.

Purpose: Atherosclerotic disease of the forearm arteries can impede the maturation of distal fistulas in diabetic patients. The goal of this study was to look at the maturity of diabetic hemodialysis patients' distal forearm (radiocephalic snuffbox or distal forearm) arteriovenous fistulas., Materials and Methods: Patients with chronic renal failure who were candidates for distal forearm radiocephalic arteriovenous fistula implantation were evaluated in this cross-sectional study. Patients' demographic details, underlying disorders, laboratory measurements, vital signs, and information on their surgery were all noted. Patients were checked for fistula development 1 week, 1 month, 2 months, and then monthly until 6 months after surgery. Arteriovenous fistula maturation characterized by optimal blood flow, vessel dilation, and structural adaptations., Results: Among 343 patients (56% male, 44% female, mean age: 57.32 ± 12.48 years), hypertension prevailed (81.9%), followed by hyperlipidemia (42.3%) and coronary artery disease history (25.9%). AVFs achieved 58.3% maturation in 64.98 ± 11.05 days; higher BP during creation correlated with successful maturation (17.02 ± 1.46 mmHg vs 13.90 ± 1.93 mmHg, P < .05). No significant statistical difference found in distal forearm arteriovenous fistula maturation between males (57.8%) and females (58.9%) ( P > .005). However, 41.7% of AVFs failed in 18.83 ± 17.89 days. Failed AVFs exhibited lower BP during operation and failure (11.75 ± 1.86 mmHg). Kaplan-Meier analysis depicted maturation probabilities over 90 days post-surgery., Conclusion: Diabetes and patient sex did not affect the maturation time of distal forearm AVFs in hemodialysis patients. Increased blood pressure during and after surgery correlated with shorter maturation time., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: The objective of this study was to investigate the flow effects in different degrees of thoracic aortic stent graft protrusion extension by creating bird beak effect simulations using accurate 3D geometry and a realistic, nonlinear, elastic biomechanical model using computer-aided software SolidWorks., Methods: Segmentation in 3D of an aortic arch from a computed tomography (CT) scan of a real-life patient was performed using SolidWorks. A parametric analysis of three models was performed: (A) Aortic arch with no stent, (B) 3 mm bird-beak configuration, and (C) 6.5 mm bird-beak configuration. Flow velocity, pressure, vorticity, wall shear stress (WSS), and time average WSS were assessed., Results: The flow velocity in Model A remained relatively constant and low in the area of the ostium of the brachiocephalic artery and doubled in the left subclavian artery. On the contrary, Models B and C showed a decrease in velocity of 52.3 % in the left subclavian artery. Furthermore, Model B showed a drop in velocity of 82.7% below the bird-beak area, whereas Model C showed a decline of 80.9% in this area. The pressure inside the supra-aortic branches was higher in Model B and C compared with Model A. In Model A, vorticity only appeared at the level of the descending aorta, with low to non-vorticity in the aortic arch. In contrast, Models B and C had an average vorticity of 241.4 Hz within the bird beak area. Regarding WSS, Model A, and Model B shared similar WSS in the peak systolic phase, in the aortic arch, and the bird beak area, whereas Model C had an increased WSS by 5 Pa on average at these zones., Conclusion: In the present simulations' lower velocities, higher pressures, vortices, and WSS were observed around the bird beak zone, the aortic arch, and the supra-aortic vessels., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Purpose: To investigate the relationship between the morphological structure and hemodynamic properties of the compressed iliac vein and explore the reason for the formation of thrombosis in the compressed iliac vein., Materials and Methods: A total of 11 patients with iliac vein compression syndrome (IVCS) were included in this study, and their iliac veins were reconstructed in 3 dimensions (3D). The morphological structures of the iliac veins (confluence angle, degree of stenosis) were analyzed based on the 3D model. Variations in the hemodynamic properties of the iliac vein were investigated at 4 typical moments in one cardiac cycle, and the relationship between the different morphological configurations and the pressure difference was investigated., Results: In the region of the compressed iliac vein, the blood flow velocity is accelerated and the pressure changes abruptly accompanied by the increase in pressure difference. Higher time averaged wall shear stress (TAWSS) and lower relative residence time (RRT) appeared in stenosis regions of compressed iliac vein, while TAWSS was low and RRT was large near the stenosis position. There was a strong positive correlation between the degree of stenosis and the pressure difference (r=0.894), and a positive correlation between the confluence angle of the iliac vein and the pressure difference (r=0.638)., Conclusion: The morphological structure of the compressed iliac vein has an obvious influence on the hemodynamic surroundings; the pressure difference becomes larger when the degree of stenosis and the confluence angle increase. The iliac vein luminal areas with low TAWSS and high RRT near the compressed location can impede blood flow and lead to accumulation of blood components, which may increase the risk of thrombosis formation and should be fully considered in the treatment of IVCS., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Purpose: The kissing stent (KS) method is low-risk compared with open surgery techniques. It is often used to treat aorto-iliac occlusive disease (AIOD). Deployment of the KS geometry has a high technical success rate. However, stent patency reduces in the first 5 years potentially due to deleterious flow behavior. Potentially harmful hemodynamics due to the KS were investigated in vitro., Methodology: A compliant phantom of the aorto-iliac bifurcation was manufactured. Two surrogate stent-grafts were deployed into the phantom in the KS configuration to investigate effects of the presence of the stents, including the compliance mismatch they cause, on the hemodynamics proximal and distal to the KS. The investigation used pulsatile flow through a flow circuit to simulate abdominal aortic flow. Particle image velocimetry (PIV) was used to quantify the hemodynamics., Results: PIV identified peak proximal and distal velocity in vitro was 0.71 and 1.40m·s -1 , respectively, which were within physiological ranges. Throughout systole, flow appeared normal and undisturbed. A lumen wall collapse in the sagittal plane formed during late systole and continued to early diastole proximal to the aorto-iliac bifurcation, distal to the inlet stent position. The wall collapse led to disturbed flow proximal to the stented region in early diastole producing potential recirculation zones and abnormal flow patterns., Conclusion: The normal systolic flow behavior indicates the KS configuration is unlikely to cause an inflammatory response of the arterial walls. The collapse has not been previously identified and may potentially cause long-term patency reduction. It requires further investigation., Clinical Impact: The role of this article is to provide further insight into the haemodynamic behavior through a stented aorto-iliac artery. The results of this investigation will improve the understanding of the effects that using the kissing stent method may have on a patient and help to identify high risk regions that may require more detailed monitoring. This paper also develops the in vitro modelling techniques that will enable further research that cannot be carried out within patients., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Endovascular interventions in infrapopliteal occlusive artery disease are becoming more complex, and this frequently tests the standard method of treatment, plain old balloon angioplasty (POBA). The potential that serration angioplasty could produce a more acceptable tibial artery lumen was assessed in this study., Aim: The aim of this single-center subgroup analysis was to compare acute angiographic results after endovascular treatment using the Serranator serration balloon catheter in patients participating in the PRELUDE-BTK trial with POBA of the infrapopliteal arteries. A secondary objective was to assess post-treatment hemodynamic improvements., Methods: Our center enrolled 15 subjects and treated 17 lesions within the multicenter prospective core laboratory-adjudicated PRELUDE-BTK study. A 25 lesions analyzed separately were treated with POBA and then compared with the Serranator subset. In both cohorts, lesions were treated with either plain angioplasty or Serranator as a stand-alone therapy; subsequent methods, such as drug elution technologies, were not used. Acute angiographic results were analyzed by the SynvaCor angiographic core laboratory. To assess volumetric flow rates, data were analyzed with a fluid flow simulation software and compared against Poiseuille's Law., Results: Final residual stenosis was 17.2%±8.2% in the Serranator group versus 33.7%±15.7% in the POBA group. The mean lumen diameter (MLD) gain for the Serranator group and the POBA group was 1.64±0.41 mm and 1.33±0.63 mm, respectively. The average atmospheric balloon inflation pressure was 5 ATM in the Serranator group versus 9 ATM in the POBA group. Neither group required a bailout stent; however, it was notable that there were significantly more chronic total occlusions (CTOs) treated in the Serranator group at 41.2% versus 12% in the POBA group. Regarding the effectiveness in improving hemodynamic blood flow for non-CTO lesions, the calculated average ratio of post-treatment to pre-treatment flow rates in the Serranator group was 238% than that for the POBA group. For CTO cases where pre-treatment flow rate was zero, final residual stenosis was used as the parameter for comparison. The Serranator group showed a 62% improvement in final residual stenosis over POBA., Conclusion: Endovascular treatment of the infrapopliteal arteries by use of the Serranator serration balloon provides a novel and promising method of action compared with standard balloon angioplasty and, thus, may have a leading role in complex below-the-knee arterial lesions., Clinical Impact: The Serranator device might help to adequately address issues with conventional routine techniques for the treatment of complex lesions in infrapopliteal arteries in patients with advanced stages of PAD and critical limb ischemia. Integrating modern technologies such as the Serranator balloon catheter into clinical routine is mandatory in order to gain a more favorable outcome in these severely diseased patients and, particularly, to reduce mortality and morbidity., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Up to 10% of hemodialysis patients with an arteriovenous fistula (AVF) suffer hemodialysis access induced distal ischemia (HAIDI). We report a treatment option of HAIDI by proximalization of arterial inflow (PAI) to the axillary artery as native upper arm loop and salvaging the matured forearm cephalic vein after previous creation of a radio-cephalic AVF (RCAVF)., Methods: A 79-years-old multimorbid male patient with end-stage kidney disease presented with an elsewhere placed left-sided RCAVF. With the start of cannulations, the patient suffered severe HAIDI. Due to the low/normal AVF-flow of 550 ml/min, a PAI procedure using the matured forearm cephalic and upper arm basilic veins in a form of native upper arm loop was performed., Results: Patient's symptoms resolved postoperatively with successful cannulations and tunneled dialysis catheter removal after 5 weeks. During a follow-up period of 64 months, several interventions were performed to maintain the patency, yet the AVF remained patent for >5 years., Conclusions: This modified PAI technique using native vessels in form of upper arm loop graft is a feasible and durable option to maintain long-term cumulative patency and should be considered as a valid native treatment option for HAIDI., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Arteriovenous fistula (AVF) is the preferred vascular access (VA) for hemodialysis, but it is associated with high non-maturation and failure rates. Predicting patient-specific AVF maturation and postoperative changes in blood flow volumes (BFVs) and vessel diameters is of fundamental importance to support the choice of optimal AVF location and improve VA survival. The goal of this study was to employ machine learning (ML) in order to give physicians a fast and easy-to-use tool that provides accurate patient-specific predictions, useful to make AVF surgical planning decisions., Methods: We applied a set of ML approaches on a dataset of 156 patients. Both parametric and non-parametric ML approaches, taking preoperative data as input, were exploited to predict maturation, postoperative BFVs, and diameters. The best approach associated with lowest cross-validation errors between predictions and real measurements was then chosen to provide estimates and quantify prediction errors., Results: The k -NN was the best approach to predict brachial BFV, AVF maturation, and other VA variables, and it was also associated with the least computational effort. With this approach, the confusion matrices proved the high accuracy of the prediction for AVF maturation (96.8%) and the low absolute error distribution for the continuous BFV and diameter variables., Conclusions: Our data-based approach provided accurate patient-specific predictions for different AVF configurations, requiring short computational time as compared to a physical model we previously developed. By supporting VA surgical planning, this fast computing approach could allow AVF surgical planning and help reducing the rate of non-maturation, which might ultimately have a broad impact on the management of hemodialysis patients., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Peripheral artery disease (PAD) can present as chronic limb threatening ischemia (CLTI) with ischemic pain and tissue loss. Progression of distal disease can lead to a "no option" or end-stage disease without traditional open or endovascular revascularization due to lack of pedal targets. Innovations in endovascular technology allow for the use of percutaneous deep vein arterialization (pDVA) to treat patients with CLTI. Purpose: We describe our experience and technique for treating four patients with end-stage PAD with pDVA. Research Design: Four patients with end-stage PAD were followed during and after pDVA creation. Technical success, complications, wound healing, and freedom from major amputation were analyzed. Data Collection and Analysis: Patient data and outcomes were collected via chart review and at time of follow up appointments in vascular surgery clinic. Results: Technical success was 100%, without post-procedural complications, and patients were continued on antiplatelet and anticoagulation. Three patients (75%) had successful wound healing, with 2 patients healing after transmetatarsal amputation (TMA), and 1 healing a distal foot ulceration that did not require surgery. One patient had worsening ischemic breakdown of a TMA, despite re-intervention on the pDVA, which required a below knee amputation (BKA). Freedom from major amputation was 75% overall, with an average follow-up time of 410 days post-procedure (Range: 113-563 days). Conclusions: Percutaneous deep vein arterialization attempts to provide blood flow to the preserved venous bed in patients with end-stage PAD. Exploration and utilization of this technique continues to expand in the modern vascular era. This case series highlights 4 patients with end-stage PVD who underwent pDVA, with 100% procedural success, and 75% limb salvage rate., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: The long-term survival and low complication rate of autogenous fistulas for hemodialysis access is often offset by early thrombosis and slow or failed maturation leading to the use of central venous catheters. A regenerative material may have the potential to overcome these limitations. A completely biological acellular vascular conduit was investigated in this first-in-human clinical study., Methods: With approval of the ethics board and patients' informed consent, five subjects were enrolled based on predetermined inclusion criteria. Five patients underwent implant of a novel acellular, biological tissue conduit (TRUE AVC™) in the upper arm in a curved configuration between brachial artery and axillary vein. After maturation, standard dialysis was commenced through the new access. Patients were followed up to 26 weeks with ultrasound and physical exam. Serum samples were evaluated for an immune response to the novel allogeneic human tissue implant., Results: This new tissue conduit handled well surgically, with properties similar to that of native human vein. Post procedure conduit flow was excellent in all cases, averaging 1098 ± 388 ml/min at week 4 and remaining stable through 1248 ± 355 ml/min at 26 weeks. Surgical site healing was normal with no edema or erythema by week 4. Six-month primary assisted patency was 80% and secondary patency was 100%. Prescribed dialysis was successfully delivered without infection, and there was no significant change in conduit diameter. Serum testing showed no increase in PRA or IgG specific to the TRUE AVC. One implant required intervention at 5 months with thrombectomy and covered stent procedure., Conclusion: This first-in-human 6-month study with favorable patency and low complication rate establishes the initial safety and feasibility of this novel biological tissue conduit for dialysis access in patients with end-stage kidney disease. Its mechanical durability and lack of immune response establishes TRUE AVC as a potential regenerative material for clinical use., Competing Interests: Declaration of conflicting interestsAH, CP, KG, MM, KS, RM, MS and ZS are share-holders and employee of Vascudyne. HW is paid consultant for Vascudyne.

Background: Arterial calcification due to deficiency of CD73 (ACDC; OMIM 211800) is a rare genetic disease resulting in calcium deposits in arteries and small joints causing claudication, resting pain, severe joint pain, and deformities. Currently, there are no standard treatments for ACDC. Our previous work identified etidronate as a potential targeted ACDC treatment, using in vitro and in vivo disease models with patient-derived cells. In this study, we test the safety and effectiveness of etidronate in attenuating the progression of lower-extremity arterial calcification and vascular blood flow based on the computed tomography (CT) calcium score and ankle-brachial index (ABI)., Methods: Seven adult patients with a confirmed genetic diagnosis of ACDC were enrolled in an open-label, nonrandomized, single-arm pilot study for etidronate treatment. They took etidronate daily for 14 days every 3 months and were examined at the NIH Clinical Center bi-annually for 3 years. They received a baseline evaluation as well as yearly follow up after treatment. Study visits included imaging studies, exercise tolerance tests with ABIs, clinical blood and urine testing, and full dental exams., Results: Etidronate treatment appeared to have slowed the progression of further vascular calcification in lower extremities as measured by CT but did not have an effect in reversing vascular and/or periarticular joint calcifications in our small ACDC cohort., Conclusions: Etidronate was found to be safe and well tolerated by our patients and, despite the small sample size, appeared to show an effect in slowing the progression of calcification in our ACDC patient cohort. (ClinicalTrials.gov Identifier NCT01585402) ., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: Low primary patency rate is a major problem of radio-cephalic arteriovenous fistula (RC-AVF) creation. Radial artery deviation and reimplantation (RADAR) is associated with low juxta-anastomotic stenosis rate. However, inflow artery stenosis is prominent with RADAR. To further reduce injury to veins and arteries during operation, a modified no-touch technique (MNTT) was used to create RC-AVF., Methods: We retrospectively reviewed our prospectively maintained database of patients with end-stage renal disease (ESRD)s undergoing RC-AVF creation for hemodialysis using either the MNTT between January 2021 and January 2022 (MNTT group) or conventional surgical procedure ( end-to-side vein-to-artery anastomosis) between October 2016 and October 2017 (Control group). Patients who chose to undergo RC-AVF surgery underwent standardized preoperative mapping and postoperative fistula evaluations using duplex ultrasound. Additionally, 4D flow MRI data were used to visualize and quantify the hemodynamics of one RC-AVF by MNTT. Outcomes included primary patency, juxta-anastomotic stenosis, and maturation rates., Results: Forty patients underwent RC-AVFs by MNTT, compared to 60 patients in the control group. The MNTT group had a higher primary unassisted patency rate than the control group ( p  = 0.038). Juxta-anastomotic stenosis (all on the cephalic vein) occurred in 4 (10%) patients who underwent MNTT. RC-AVF maturation rates after 3 months were not different between both groups (maturation rate: 90% and 81.7% in the MNTT and control groups, respectively, p  = 0.253). COX regression showed that both conventional AVF surgery ( p  = 0.031) and smaller cephalic vein diameter ( p  = 0.034) were associated with higher odds of RC-AVF failure. The AVF flow within the proximal vein remained helical during cardiac cycle. The distribution of wall shear stress (WSS) and oscillatory shear index (OSI) differed from that of conventional surgical AVF., Conclusion: RC-AVF by MNTT increases primary patency rate and decreases juxta-anastomotic stenosis rate. The improvement in hemodynamics may be one of the important reasons for the better patency rate of in the RC-AVF by MNTT group., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: The current Spanish Clinical Guidelines on Vascular Access for Hemodialysis support the need for surveillance and monitoring of vascular access (VA) to avoid complications. Ultrasound dilution (UD) methods are accepted for the evaluation of VA flow and Transonic® has established the gold standard method for the measurement. The DMed NephroFlow (NIPRO®) device, based on UD method has recently been incorporated. We report a comparative study between the classic Transonic® versus the new NephroFlow® device., Material and Methods: For two consecutive months, measurements of VA flow using both referred systems were performed in patients with a native arteriovenous fistula (AVF) or a graft (AVG) on hemodialysis (HD) in our unit. Both studies were undertaken according to the usual recommendations: VA flow of 250 ml/min, ultrafiltration rate without modifications, both needles in the same vein, and always in the first hour of the HD session., Results: Forty-five patients were included: 17 women and 28 men, mean age of 67 ± 12 years. Thirty patients were diabetic. The baseline meantime on HD was 51 ± 39 months (range: 3-163). Type of VA was: 17 patients radio-cephalic AVF, 17 brachiocephalic AVF, 7 brachiobasilic AVF, and 3 with a graft. The mean flow estimated by the Transonic® was 1222 ± 805 ml/min and the estimated flow by the NephroFlow® device was 1252 ± 975 ml/min. Good reliability between Transonic® and NephroFlow® was observed, with a reliability index of Cronbach's Alpha of 0.927 and an Intraclass Correlation Index of 0.928., Conclusions: The NephroFlow® device seems comparable with the accepted gold standard UD method for estimating VA flow. More studies must be performed to verify these results. However, they should be considered for the surveillance and monitoring of VA flow, in agreement with the Spanish Guidelines., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: The placement of vascular catheters of adequate size in accordance to catheter-to-vein ratio (CVR) recommendations represents one of the cornerstones of catheter-related upper vein thrombosis prevention. However there is scarcity of data on its effect on the venous dynamics of the basilic vein, a common site for long-term catheter placement. This study investigates the effects of the application of positive airway pressure on the diameter and blood flow velocity of basilic vein. We also measured the effects of under-armpit straps, a device commonly used to keep continuous positive airway pressure (CPAP) helmets in place., Methods: We enrolled 28 healthy volunteers. Basilic vein diameter and minimum/maximum blood flow velocity, according to respiratory venous flow oscillation, were measured by ultrasound on the midpoint of their dominant arm during spontaneous breathing and during breathing in a CPAP helmet with 10 cm H 2 O of airway pressure applied, with the helmet kept in place either through armpit straps or by tying the helmet to the bed., Results: The application of 10 cm H 2 O of positive airway pressure significantly increased basilic vein diameter by 0.9 ± 0.2 mm, while reducing minimum blood flow velocity by 1.8 ± 0.4 cm/s. These effects were amplified by the application of under armpit straps., Conclusions: Breathing with positive airway pressure increases basilic vein diameter while reducing blood flow-velocity. This phenomenon might lead to an incorrect assessment of CVR, misleading the operator into choosing improperly large catheters., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: Severe ischemia is a rare complication of radial artery catheterization (RAC). This study aims to summarize risk factors of RAC-elicited severe hand ischemia, preventive, and therapeutic management., Methods: Literature search was conducted in eight electronic English and Chinese databases to identify relevant published cases. Data of interest was extracted and analyzed., Results: Database search identified 28 articles reporting cases of 57 patients developing hand ischemia following RAC. Patients aged between 1 day and 88 years. The indications for RAC included surgery, shock, cardiac arrest, and Neonatal Intensive Care Unit (NICU) admission. Identified risk factors included pre-existing vascular diseases, hypotension, arterial anatomical abnormality or small diameter, vasoconstrictors, and catheter-related problems. Totally, 18 patients complained pain; 32 developed discoloration; 19 pulselessness; 3 paresthesia; 13 swolleness and 19 coldness. Eventually, 30 patients recovered well, but 20 patients unfortunately underwent digital amputation and three patients deceased due to non-RAC-related causes., Conclusion: Severe hand ischemia following RAC is a rare complication, with the reported incidence of approximately 0.09%. There is no definite predictor for RAC-related hand ischemia, but patients with risk factors are prone to the occurrence of hand ischemia. It's vital to initiate early recognition and proactive strategies for a best practice RAC insertion., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

We report a case series of four patients with radial artery occlusion complicating vascular access who were scheduled for coronary angiography. We describe the challenges in selecting adequate vascular access in patients with a history of coronary angiography and percutaneous coronary intervention, as well as the benefits of using preprocedural ultrasound examination of forearm arteries to detect radial artery occlusion. Our case series suggests that if the anterior interosseous artery provides partial blood supply to the hand as a collateral circulation of the occluded radial artery, the transulnar approach may be an alternative safe option for coronary angiography and percutaneous coronary intervention in this population., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Volume flow (Qa) > 1.5-2 l /minQa in arteriovenous accesses may be associated with high flow related systemic or locoregional complications. A variety of surgical techniques are advocated for Qa reduction. Aim of this scoping review is to provide an overview of available evidence regarding the efficacy of this broad spectrum of interventions for Qa reduction in patients with a high flow haemodialysis access. PubMed and Embase were searched according to PRISMA-guidelines. Studies on invasive management of HFA were selected. Inclusion required an English description of surgical techniques in human HFAs including pre- and postoperative access flow-values. Sixty-six studies on 940 patients (mean age 56 years (3-90 years), male 62%, diabetes mellitus 26%, brachial artery-based arteriovenous access 65%) fulfilled inclusion criteria. Performed techniques were banding (58%), revision using distal inflow (12%), plication/anastomoplasty (10%), graft interposition (5%), proximal radial artery ligation (3%), aneurysm repair (4%), or miscellaneous other techniques (8%). Definition of HFA, work-up, indication for surgery and intraoperative monitoring were diverse. All techniques reduced Qa on the short term (mean drop 0.9-1.7 l/min). Secondary access patency rates varied between 70% and 93% (mean follow-up 15 (0-189) months). Definitions of success and recurrence varied widely precluding a comparison of efficacy of techniques. Patient specific factors legitimizing invasive treatment for HFA are discussed. Recommendations on reporting standards when dealing with HFA surgery are provided. In conclusion, the present report on the current management of high flow access does not allow for drawing any definite conclusions due to a lack of standardization in definition, indications for surgical intervention and techniques. Randomized trials comparing different Qa reducing techniques in symptomatic patients are warranted, as are trials comparing a wait-and-see approach versus Qa reduction in asymptomatic patients. As an overview of the variety of techniques was lacking, this scoping review might serve as a map for future researchers., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: The reduction in distal arterial flow following arteriovenous fistula (AVF) creation can cause a perfusion deficit known as haemodialysis access induced distal ischemia (HAIDI). Various techniques have been advocated to treat this difficult problem with varying success. We present the long-term outcomes following a novel banding technique., Methods: 46 patients in this cohort from 2008 to 2021 underwent a novel banding procedure using a Dacron™ patch shaped with one slit-end and saw-tooth edges (resulting in a 'Christmas-tree' pattern) to provide a ratchet mechanism to progressively constrict the fistula outflow. Real-time finger perfusion pressure monitoring allowed an accurate reduction in AVF flow whilst increasing distal arterial perfusion pressure. Baseline characteristic were recorded and Kaplan-Meier survival curves were obtained to calculate the post-intervention primary, assisted primary and secondary patency., Results: 29 patients presented with rest pain and 11 presented with tissue loss due to distal ischemia. The post-intervention primary access patency was 100%, 98%, 78% and 61% at 30, 60 and 180 days and 1 year respectively. Complete resolution of symptoms was achieved in 74% ( n  = 34) of patients and a partial response needing no further intervention was achieved in 11% ( n  = 5) of patients. A Youden index calculation suggested that digital pressures of 41 mm Hg or lower in an open AVF were highly sensitive for symptomatic hand ischemia whereas pressures greater than 65 mm Hg ruled out distal ischemia., Conclusion: 'Christmas-tree' banding with on table finger systolic pressures is not only an efficacious and durable method for treating HAIDI but also preserves fistula patency., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: In elderly and diabetic patients, arterial calcifications are prevalent and result in worse outcomes of arterio-venous fistulas (AVFs). Optimal ultrasound criteria for assessment of calcified arteries are unknown. We report our experience with ultrasound assessment of calcified arteries prior to placement of radio-cephalic (RC) AVFs., Material and Methods: We included 85 patients in whom a RC-AVF placement was planned. Patients were divided according to the presence of radial artery calcifications into a calcified group (moderate/severe calcifications, N  = 18) and control group (no changes/mild atherosclerosis, N  = 67). Doppler ultrasound parameters were analyzed in the calcified group with focus on assessment of the artery, including grading of calcifications and Doppler measurements at rest and during reactive hyperemia (RH)., Results: In the calcified group mean patients' age was 72 ± 11 years, 72% were diabetics, mean resistance index (RI) during RH was 0.78 ± 0.09 (range 0.63-0.90). In 14 (78%) patients an AVF was successfully placed and in 12 it matured (67% maturation rate). A lower RI at rest was observed in the primary failure sub-group with high area under the ROC curve (0.89) and a cut-off value of 0.90 for RI. There was no difference in RI at RH between failed and matured AVFs. 1-year secondary patency was 66% and in eight patients with follow-up ultrasound available, blood flow was 350-1300 ml/min. For comparison, in the control group a radio-cephalic AVF was placed in all patients, primary failure rate was 6%, maturation rate 85% and 1-year secondary patency was 77%., Conclusions: Our very limited experience suggests that successful RC-AVF placement and maturation with good 1-year patency rates is possible in patients with moderately/severely calcified arteries and RI during RH of up to 0.90., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Arterial aneurysms remain a significant public health problem because they often result in death when ruptured; therefore, they require immediate medical treatment. Endovascular aneurysm repair (EVAR) has recently become the primary treatment option, owing to the fewer side effects compared to those with open surgery. However, stents used for conventional EVAR often cause side-branch occlusion, which alters the perfusion of vital organs. Recently, multilayer flow modulator (MFM) stents have been used as a new treatment for arterial aneurysms. These stents appear to be feasible owing to their unique design consisting of an uncoated three-dimensionally braided multilayered structure. MFM stents generally remodulate laminar flow and reduce the flow velocity in the aneurysmal sac, leading to thrombosis, which causes the aneurysm to shrink over time. Thus, they reduce the risk of mortality. Moreover, they reduce morbidity by preserving the side-branch blood flow. They can be easily applied to complex aneurysms and are ready to use without customization, which shortens the waiting time for interventions. This study aimed to evaluate the role of MFM stents in the treatment of arterial aneurysms based on available data.