Spatial Transcriptomic Profiling of Human Saphenous Vein Exposed to Ex Vivo Arterial Haemodynamics-Implications for Coronary Artery Bypass Graft Patency and Vein Graft Disease.

Vein graft disease is the process by which saphenous vein grafts, utilised for revascularisation during coronary artery bypass graft surgery, undergo an inflammation-driven intimal hyperplasia and accelerated atherosclerosis process in subsequent years after implantation. The role of the arterial circulation, particularly the haemodynamic properties' impact on graft patency, have been investigated but have not to date been explored in depth at the transcriptomic level. We have undertaken the first-in-man spatial transcriptomic analysis of the long saphenous vein in response to ex vivo acute arterial haemodynamic stimulation, utilising a combination of a custom 3D-printed perfusion bioreactor and the 10X Genomics Visium Spatial Gene Expression technology. We identify a total of 413 significant genes (372 upregulated and 41 downregulated) differentially expressed in response to arterial haemodynamic conditions. These genes were associated with pathways including NFkB, TNF, MAPK, and PI3K/Akt, among others. These are established pathways involved in the initiation of an early pro-inflammatory response, leukocyte activation and adhesion signalling, tissue remodelling, and cellular differentiation. Utilising unsupervised clustering analysis, we have been able to classify subsets of the expression based on cell type and with spatial resolution. These findings allow for further characterisation of the early saphenous vein graft transcriptional landscape during the earliest stage of implantation that contributes to vein graft disease, in particular validation of pathways and druggable targets that could contribute towards the therapeutic inhibition of processes underpinning vein graft disease.

Superior long-term patency of no-touch vein graft compared to conventional vein grafts in over 1500 consecutive patients.

OBJECTIVES: To evaluate the long-term angiographic patency of saphenous vein grafts (SVG) harvested using the no-touch technique compared to the conventional technique. METHODS: This was a single-center, retrospective, cohort study. The inclusion criteria were individuals who underwent a CABG (coronary artery bypass grafting) between January 1995 and July 2020, and who successively needed a clinically-driven angiography. The primary endpoint was long-term patency. The secondary endpoints were differences in patency based on sub-group analysis (single vs. sequential graft, divided by target vessel). RESULTS: The study included 1520 individuals (618 no-touch, 825 conventional and 77 arterial grafts). The mean clinical follow-up time was 8.4 years ± 5.5 years. The patency per patient was 70.7% in the no-touch grafts vs. 46.7% in the conventional grafts (p < 0.001, OR = 2.8). The graft patency was 75.9% in the no-touch grafts vs. 62.8% in the conventional grafts (p < 0.001, OR = 1.8). CONCLUSIONS: The no-touch vein grafts were associated with statistically significantly higher patency at long-term compared to the conventional grafts. CLINICAL TRIAL REGISTRATION: NCT04656366, 7 December 2020.

[Stenotic FAV: Success of the Collaboration Between Spoke and HUB].

The arteriovenous fistula constitutes the vascular access of first choice in hemodialysis. We present three clinical cases that highlight the resolution in interventional radiology of venous stenosis, one of the major complications. Clinical monitoring and instrumental diagnostics with color Doppler ultrasound have prevented the failure of the AVF due to high risk of thrombosis. The angiographic interventions, thanks to the collaboration between Spoke and Hub, were completed without complications.

Assessment of primary patency for femoropopliteal graft entrapment within the sartorius muscle.

PURPOSE: Blind tunneling of subfascial femoropopliteal bypass grafts may result in inadvertent graft passage through the sartorius. The purpose of this study was to determine whether intramuscular passage of femoropopliteal bypass grafts affects primary patency. METHODS: Patients undergoing femoropopliteal bypass at a Veterans Administration hospital and associated university medical center over a recent 13-year period who also had postoperative cross-sectional imaging adequate to determine graft location were examined. Five-year primary patency of grafts circumferentially enveloped by the muscle was compared with that of both extramuscular subfascial grafts and subcutaneous grafts. RESULTS: 370 femoropopliteal grafts were identified, among which 258 (70%) were subfascial. Vein grafts comprised 51% of the subfascial grafts, and 53% were inserted above the knee. Available postoperative imaging in 110 subfascial grafts demonstrated 74 (67%) to lie completely within the muscle at some point. Among imaged subfascial grafts, primary patency at five years for intramuscular grafts was not significantly worse than extramuscular grafts (P = 0.31). This remained true whether grafts were vein (P = 0.39) or prosthetic (P = 0.31) and whether grafts inserted to the above-knee (P = 0.43) or below-knee (P = 0.21) popliteal artery. Multivariable Cox regression revealed a significant relationship between use of vein grafts (P = 0.013), active smoking (P = 0.01), and hypertension (P = 0.041) and primary patency, but not intramuscular graft location (P = 0.31). CONCLUSION: This study failed to demonstrate significantly inferior primary patency among subfascial femoropopliteal grafts tunneled intramuscularly. Larger studies may be required to adequately detect any differences in patency by muscular entrapment, especially among subgroups.

Perioperative Vascular Access Mapping in Patients with Hemodialysis: A Comparative Study of Access Navigation and Selection in Jordan.

Purpose: This study aimed to elucidate the impact of three different mapping methods on the outcomes of arteriovenous fistula (AVF), including the traditional physical examination (PE) method, color duplex ultrasonography (CDU) mapping conducted by a radiologist (CDU-R), and CDU mapping performed by the operating surgeon (CDU-S). Patients and Methods: This retrospective study was conducted at a tertiary center in Jordan. Patients were divided into three groups based on the venous mapping method: PE, CDU-R, and CDU-S. Various outcomes were analyzed, including immediate technical success, clinical adequacy at 3 months, and 1-year patency rates. Additional demographic and clinical factors influencing access patency or contributing to early failure were also examined. Results: The study included 303 eligible patients: 100 in the PE group, 103 in the CDU-R group, and 100 in the CDU-S group. The overall immediate technical success rate was 72%, which was highest in the CDU-S group (95%, p < 0.001). Additionally, the CDU-S group had the highest clinical access adequacy rate (78%, p < 0.01). Notably, the mapping method also influenced the anatomical location of the AVF, as none of the patients in the radiologist group had a forearm AVF. CDU-R, forearm location, intraoperative arterial calcifications, and operative duration were identified as predictors of AVF failure. Conclusion: The results suggest that perioperative vascular mapping by the operating surgeon not only results in a higher rate of immediate success but also improves access adequacy and prevents unnecessary delays in providing an effective lifeline for hemodialysis patients. The present study highlights the burden of access failure in these patients and the evolving evidence surrounding preoperative vein mapping.

The application of blood flow sound contrastive learning to predict arteriovenous graft stenosis of patients with hemodialysis.

End-stage kidney disease (ESKD) presents a significant public health challenge, with hemodialysis (HD) remaining one of the most prevalent kidney replacement therapies. Ensuring the longevity and functionality of arteriovenous accesses is challenging for HD patients. Blood flow sound, which contains valuable information, has often been neglected in the past. However, machine learning offers a new approach, leveraging data non-invasively and learning autonomously to match the experience of healthcare professionas. This study aimed to devise a model for detecting arteriovenous grafts (AVGs) stenosis. A smartphone stethoscope was used to record the sound of AVG blood flow at the arterial and venous sides, with each recording lasting one minute. The sound recordings were transformed into mel spectrograms, and a 14-layer convolutional neural network (CNN) was employed to detect stenosis. The CNN comprised six convolution blocks with 3x3 kernel mapping, batch normalization, and rectified linear unit activation function. We applied contrastive learning to train the pre-training audio neural networks model with unlabeled data through self-supervised learning, followed by fine-tuning. In total, 27,406 dialysis session blood flow sounds were documented, including 180 stenosis blood flow sounds. Our proposed framework demonstrated a significant improvement (p<0.05) over training from scratch and a popular pre-trained audio neural networks (PANNs) model, achieving an accuracy of 0.9279, precision of 0.8462, and recall of 0.8077, compared to previous values of 0.8649, 0.7391, and 0.6538. This study illustrates how contrastive learning with unlabeled blood flow sound data can enhance convolutional neural networks for detecting AVG stenosis in HD patients.

A review of the current recommendations and practices for hemodialysis access monitoring and maintenance procedures.

The growing number of prevalent arteriovenous (AV) accesses has been associated with an increase in the incidence of procedures being performed to maintain patency. To reduce the rate of unnecessary procedures, the 2019 Kidney Disease Outcome Quality Initiative guidelines addended the AV access surveillance recommendations, which includes clinical monitoring and assessment of dialysis adequacy alone. Abnormal clinical findings would necessitate follow-up angiography with or without confirmatory duplex ultrasound. Due to poor patency, increased surveillance schedules have been proposed to identify stenosis early and potentially prevent acute thrombotic events and AV access failure. In this review, we outlined current AV access monitoring and maintenance procedure recommendations, as described by the Centers for Medicare and Medicaid Services and 2019 Kidney Disease Outcome Quality Initiative guidelines. In addition, we highlight the findings of recently published randomized controlled trials that have examined increased surveillance schedules.

[Prevalence and intervention effect of arteriovenous graft stenosis].

Objective: To evaluate the prevalence, intervention methods and effect of arteriovenous graft (AVG) stenosis. Methods: The clinical data of patients who received AVG in the Blood Purification Center, the First Affiliated Hospital of Zhengzhou University from January 2018 to December 2022 were retrospectively analyzed. The patency rate, prevalence and intervention effect of AVG stenosis were analyzed. Results: A total of 475 patients aged (55.5±11.8) years were included, and there were 193 male cases (40.6%) and 282 female cases (59.4%). The patients were followed up for [M (Q1, Q3)] 19 (12, 30) months, and the primary, assisted primary and secondary patency were 14 (5, 27), 27 (13, 55), and 59 (33, 65) months, respectively. There were 799 access events which needed intervention, with a total standardized intervention rate of 0.90 per patient-year. Totally, 431(53.9%, 431/799) stenosis events occurred in 207 AVG. Among 422 AVG stenosis events with complete clinical data, 57.8% (244/422) were multi-site stenosis and 42.2% (178/422) were single-site stenosis. The most common sites of stenosis were graft-vein anastomosis (47.6%, 340/715), venous outflows (22.7%, 162/715), and puncture zone (20.0%, 143/715). In the 414 stenosis with intact follow-up data, 90.8% (376/414) were treated by balloon angioplasty, 8.5% (35/414) received covered stent insertion, and 0.7% (3/414) were intervened by open surgery. Clinical success rate was 98.1% (406/414). The primary patency time after endovascular treatment was 6 (4, 12) months. Covered stent significantly increased post-intervention primary patency time compared withballoon angioplasty [6 (3, 7) months vs 3 (1, 4) months, P=0.020]. Conclusions: Stenosis is the most common complication of AVG, and the most common sites are graft-vein anastomosis, venous outflows, and puncture zone. Intervention of AVG stenosis has a high clinical success rate, and a relatively low post-intervention patency. Covered stent insertion improves the post-intervention patency of AVG, which has a poor effect using balloon expansion.

[Intervention principles for complications of arteriovenous graft].

Stenosis, thrombosis, and infection are major complications of arteriovenous graft (AVG). Endovascular therapy is usually adopted for stenosis, while bypass, interposition, patch angioplasty and other surgical techniques can also be used for special sites. Interventions of AVG thrombosis include removal of thrombus and treatment of the underlying stenosis. The former includes catheter directed thrombolysis, endovascular intervention, surgical treatment, or hybrid treatment. Etiological detection before the application of empirical antibiotics is the first step of infection management. According to different infection ranges, partial graft excision and interposition, total graft excision and partial graft excision can be performed respectively. Active prevention, timely identification, and appropriate intervention of the complications can improve the long-term outcomes of AVG. Personalized interventional strategy should be employed based on the systemic evaluation.

[Factors influencing primary patency time of percutaneous transluminal balloon angioplasty for hemodialysis arteriovenous grafts].

Objective: To investigate the factors affecting primary patency time in arteriovenous graft (AVG) patients receiving percutaneous transluminal balloon angioplasty (PTA). Methods: Hemodialysis patients who underwent AVG placement at the First Affiliated Hospital of Chongqing Medical University between February 2018 and December 2021 were included. The factors including age, gender, total duration of AVG use, site of stenosis, degree of stenosis, length of stenosis, residual stenosis, and presence of thrombosis were analyzed, and influencing factors of primary patency time in AVG were determined using a multiple linear regression model. Results: A total of 101 patients who underwent 331 PTA treatments were enrolled, including 35 males and 66 females. The median age of patients undergoing PTA for the first time was 61 (51, 68) years, and the primary patency time after PTA was 5 (3, 10) months. The patients were followed up for (38.5±15.3) months. Multivariable linear regression analysis revealed that severe stenosis at the venous anastomosis and reflux veins (ß=-2.773, 95%CI:-5.440--0.105, P=0.042), female (ß=-2.247, 95%CI:-3.853--0.642, P=0.006), and previous multiple PTA treatments (ß=-0.516, 95%CI:-0.978--0.054, P=0.029) were risk factors for a shorter primary patency time after PTA. Conclusion: Severity of stenosis at the venous anastomosis and reflux veins of the AVG, female, and a history of multiple previous PTA treatments are associated with a shorter primary patency time in AVG patients.

Coronary angiography was used to assess the effect of diabetes on off-pump coronary artery bypass graft patency.

This study aimed to examine the influence of diabetes on the left internal mammary artery (LIMA) and saphenous vein (SV) graft failure for 5-year follow-up. We enrolled 202 patients who underwent isolated off-pump coronary artery bypass grafting (CABG) surgery in 2014, angiographic follow-up occurred at 5 years after surgery. Angiographic outcomes in patients with or without diabetes were analyzed. Multivariate logistic regression analysis was used to identify independent predictors of graft dysfunction. A total of 66 (32.7%) patients had diabetes. Five-year rates of LIMA and SV graft failure were similar in patients with and without diabetes. In addition, in diabetics, the proportion of complete graft failure was significantly lower in the LIMA grafts (12/66, 18.2%) than in the SV grafts (57/133, 42.9%) (P = .001). In nondiabetic, the proportion of complete graft failure was also significantly lower in the LIMA grafts (28/136, 20.6%) than in the SV grafts (105/275, 38.2%) (P < .001). Multivariate logistic regression analysis showed that mean graft flow (MGF) was an independent predictor factor for LIMA (odds ratio = 1.186, 95% CI = 1.114-1.263, P < .001) and SV (odds ratio = 1.056, 95% CI = 1.035-1.077, P < .001) graft failure. Diabetes did not influence the patency of LIMA or SV grafts over a 5-year follow-up. LIMA grafts should be maximized in patients undergoing off-pump CABG surgery. Diabetes does not affect the patency of grafts CABG. Using angiography, our study proved that diabetes does not affect the patency of grafted vessels after CABG for 5 years.

Use of dual-lumen microcatheter pullback injection in complex percutaneous coronary intervention.

Dual-lumen microcatheters (DLMC) are utilized in challenging wiring scenarios as well as for contrast and medication injections. Nonetheless, lesion characterization remains extremely challenging in many cases. We describe a DLMC-facilitated technique which can assist in locating the distal anastomosis while navigating an occluded bypass graft during retrograde chronic total occlusion recanalization, as well as in the differential diagnosis of abrupt vessel closure. This "DLMC Pullback Injection" technique is performed by injecting contrast through the over-the-wire port of the DLMC, while the latter is quickly pulled back across the region of interest in a dynamic fashion. We believe this technique has the potential to solve challenging scenarios and to enrich the complex percutaneous coronary intervention operator's armamentarium.

Long-Term Patency Between Brachiocephalic and Brachiobasilic Fistulas: A Single Institution Review.

BACKGROUND: Dialysis access is a fundamental procedure performed by vascular surgeons. Commonly, upper extremity access is utilized via a brachiobasilic fistula (BBF) or brachiocephalic fistula (BCF). BCF is preferred due to ease compared to BBF without documented improved function. Few studies compare patency outcomes between BBF and BCF over time. Our goal was to evaluate the difference in outcomes between BBF and BCF. METHODS: This is a retrospective review of patients with BCF or BBF between 2019 and 2022. Patients were split by procedure: BCF and BBF. Data collected included demographics, vein size, tunneled catheter, and previous access. Primary outcomes included primary patency (PP), primary assisted patency (PAP) and secondary patency (SP). Secondary outcomes included 30-day complications, access abandonment, interventions and mortality. Linear regression, Kaplan-Meier, and log-rank test were performed. RESULTS: Our study had 184 patients, 109 (59%) with BCF and 75 (41%) with BBF. There were no differences in demographics except for body mass index and vein size (BBF: 4 vs. BCF: 3.6 mm, P = 0.020). There was no difference in PP at 1 year (41% vs. 47%, P = 0.547) or SP at 2 years (73% vs. 84%, P = 0.058) in BBF versus BCF. However, PAP was significantly greater in BCF (80% vs. 67%, P = 0.030) at 1 year. Secondary outcomes revealed no difference in wound complications (1% vs. 0%, P = 0.408), access abandonment (35% vs. 28%, P = 0.260), or number of interventions (1 vs. 1, P = 0.712) in BBF versus BCF. Mortality was significantly greater in the BBF patients (19% vs. 6%, P = 0.005). On adjusted analysis, BBF had 43 min longer operative time (P < 0.001) and 22 cc greater blood loss (P < 0.0001). CONCLUSIONS: In this single center review comparing BBF and BCF, no difference was seen between BBF and BCF in terms of PP or SP. Even with larger vein size, BBF did not confer a benefit in long term patency or access abandonment. Additionally, BBF did not confer decreased procedures to maintain patency and BBF had greater operative length and blood loss, as well as mortality. We believe this study demonstrates that for patients who must use an upper extremity location, when the cephalic vein is satisfactory, using the cephalic vein is preferred as it does not negatively impact long-term patency.

Role and Value of Intravascular Ultrasound in the End-Stage Renal Disease Population: A Narrative Review.

Vascular access for hemodialysis is the lifeline for patients with end-stage renal disease (ESRD); therefore, maintenance of the vascular access is of the utmost importance. The dialysis circuit can be complicated by stenosis or thrombosis. In particular, central venous stenosis is frequently encountered in the vascular access of patients with ESRD, and this complication may require endovascular management. Conventional catheter-based venography may be inadequate for identifying dynamic forms of extrinsic compression and intravascular webs associated with these lesions. For these types of access complications, balloon angioplasty remains the first-line intervention, with stenting reserved for selected scenarios. Accurate assessment of the venous configuration is therefore important to ensure an adequate treatment response. Intravascular ultrasound (IVUS) has been shown to be beneficial in lower extremity venous interventions. The use of IVUS in dialysis access interventions is currently limited but may be indicated in selected challenging clinical situations. In this article, we discuss the potential uses of IVUS in the ESRD population based on our institutional experience and on the current literature.

Pathohistomorphometric and Immuno-Histologic Changes in Early Arteriovenous Fistula Failure in Patients with Chronic Kidney Disease.

BACKGROUND: Hemodialysis is a prevalent treatment for the end-stage chronic kidney disease (CKD) worldwide. The primary arteriovenous fistula (AVF), widely considered the optimal hemodialysis access method, fails to mature in up to two-thirds of the cases. The etiology of the early AVF failure, defined as thrombosis or inability to use within three months post-creation remains less understood, and is influenced by various factors including patient demographics, surgical techniques, and genetic predispositions. Neointimal hyperplasia is a primary histological finding in stenotic lesions leading to the AVF failure. However, there are insufficient data on the cellular phenotypes and the impact of the preexisting CKD-related factors. This study aims to investigate the histological, morphometric, and immunohistochemical alterations in the fistula vein, pre-, peri-, and post-early failure. MATERIALS AND METHODS: Eighty-nine stage 4-5 CKD patients underwent standard preoperative assessment, including the Doppler ultrasound, before a typical radio-cephalic AVF creation. Post-failure, a new AVF was created proximally. The vein specimens were collected during the surgery, processed, and analyzed for morphometric analyses and various cellular markers, including Vimentin, TGF, and Ki 67. RESULTS: The study enrolled 89 CKD patients, analyzing various aspects of their condition and AVF failures. The histomorphometric analysis revealed substantial venous luminal stenosis and varied endothelial changes. The immunohistologic analysis showed differential marker expressions pre- and post-AVF creation. CONCLUSION: This study highlights the complexity of the early AVF failures in CKD patients. The medial hypertrophy emerged as a significant preexisting lesion, while the postoperative analyses indicated a shift towards neointimal hyperplasia. The research underscores the nuanced interplay of vascular remodeling, endothelial damage, and cellular proliferation in the AVF outcomes.

Safety and Performance of a Cell-Impermeable Endoprosthesis for Hemodialysis Vascular Access Outflow Stenosis: A Brazilian Multicenter Retrospective Study.

PURPOSE: To evaluate the safety and performance of Wrapsody™, a cell-impermeable endoprosthesis (CIE), for treating hemodialysis vascular access outflow stenosis. MATERIALS AND METHODS: Investigators retrospectively analyzed 113 hemodialysis patients treated with a CIE (11/2021-12/2022) across four centers in Brazil. De novo or restenotic lesions were treated. The primary efficacy outcome measure was target lesion primary patency (TLPP) at 1, 3, 6, and 12 months; the primary safety outcome measure was the absence of serious local or systemic adverse events within the first 30 days post-procedure. Secondary outcome measures included technical and procedural success, access circuit primary patency (ACPP), and secondary patency at 1, 3, 6, and 12 months post-procedure. RESULTS: Thirty-nine patients (34.5%) had thrombosed access at the initial presentation, and 38 patients (33.6%) presented with recurrent stenosis. TLPP rates at 1, 3, 6, and 12 months were 100%, 96.4%, 86.4%, and 69.7%, respectively. ACPP rates were 100% at 1 month, 89.2% at 3 months, 70.9% at 6 months, and 56.0% at 12 months. The target lesion secondary patency rates at 1, 3, 6, and 12 months were 100%, 97.3%, 93.6%, and 91.7%, respectively. In the adjusted multivariate Cox regression analysis, male sex and endoprosthesis with diameters of 10, 12, 14, and 16 mm were associated with improved primary patency rates. No localized or systemic serious adverse event was observed through the first 30 days post-procedure. CONCLUSION: The CIE evaluated in this study is safe and effective for treating peripheral and central outflow stenoses in hemodialysis vascular access. LEVEL OF EVIDENCE: Level 2b, cohort study.