Arteriovenous Hemodialysis Access Research Articles

#532 Association between blood flow measured within 30 days from AV access creation and the risk of thrombosis

Abstract Background and Aims The use of arteriovenous (AV) access for hemodialysis (HD) is hampered by the risk of dysfunction and thrombosis. Various factors affect the risk of AV access thrombosis, such as age, female sex, hematocrit, vessels’ diameter and anatomy, and patients’ comorbidities (e.g. diabetes mellitus, thrombophilia, chronic inflammatory disease). Previous studies have reported contradictory results on the prognostic value of intraoperative blood flow (Qa) measurements. Finally, only few studies have investigated the association between postoperative Qa measurements and thrombosis risk. Therefore, current guidelines report that there is not enough evidence to suggest routine assessment of AV access Qa for surveillance. This study aimed to analyze the association between Qa, measured at the first post-operative visit (within 30 days from creation), and thrombosis risk, in distal and proximal autologous AV fistulae (dAVF and pAVF), and AV grafts (AVG). Method This retrospective cohort study included all AV accesses created in San Paolo Hospital (Milan, IT) between January 1st 2013 and December 31st 2022, with a post-operative Qa measurement available within 30 days from the date of creation. AV accesses were classified as dAVF, pAVF and AVG. Qa was measured by ultrasound as the product of the cross-sectional area and the time-averaged mean velocity, in the feeding artery. The thrombosis-free survival of dAVF, pAVF and AVG was plotted using the Kaplan Meier method. The association between Qa and the risk of thrombosis was studied by Cox proportional hazard models, adjusted for patient's age and sex. Non-linearity was assessed using natural splines. Results A total of 218 AV accesses (92 dAVF, 76 pAVF, and 50 AVG) were created in 191 patients. At baseline, patients had a median age of 69 years, 70% were male, 42% were already on HD treatment, and overall, they had a high prevalence of hypertension, diabetes mellitus and cardiovascular comorbidities. At first post-operative visit, median Qa was 922 [698, 1278] ml/min, 1260 [917, 1825] ml/min, and 1665 [1195, 2508] ml/min, respectively for dAVF, pAVF, and AVG (p <0.001). During a median follow up time of 1.35 [0.55, 2.62] years, 66 AV access thrombosis occurred. The thrombosis-free survival rates for dAVF, pAVF and AVG were 84%, 97%, and 51% at 1 year, and 63%, 66%, and 19% at 5 years (Fig. 1). For dAVF we found a significant L-shaped association between Qa measured at the first post-operative visit and thrombosis risk, with the lowest risk found at Qa of 1289 ml/min and an exponential risk increase for dAVF with Qa <800 ml/min (Fig. 2). Particularly, for dAVF with Qa < 1289 ml/min, we found a 39% increased risk of thrombosis for every 100 ml/min decrease in Qa (aHR 1.39, 95% CI 1.10-1.75, p 0.006). In pAVF, Qa showed a trend of inverse linear association with the risk of thrombosis, although not reaching statistical significance (aHR 1.06, 95% CI 0.96-1.17, p 0.24, for every 100 ml/min decrease in Qa). In AVG, Qa was not associated with the risk of thrombosis (aHR 1.01, 95% CI 0.97-1.06, p 0.57, for every 100 ml/min decrease in Qa). Conclusion In our cohort we found that Qa, measured at the first post-operative visit, is associated with the risk of thrombosis in dAVF, but not in pAVF and AVG. In particular, in dAVF the association is non-linear with the lowest risk in our cohort found at Qa equal to 1289 ml/min, with an exponentially increasing risk for Qa <800 ml/min. Our findings suggest that post-operative flow assessment may be a useful tool to identify dAVF at higher risk of thrombosis and allow a closer monitoring or possible preventive interventions.

Characterization of long-term survival in Medicare patients undergoing arteriovenous hemodialysis access: Presented at the Midwestern Vascular Surgical Society Annual Meeting, Boston, Massachusetts, September 7-9, 2023.

Characterization of long-term survival in Medicare patients undergoing arteriovenous hemodialysis access: Presented at the Midwestern Vascular Surgical Society Annual Meeting, Boston, Massachusetts, September 7-9, 2023.

Characterization of long-term survival in Medicare patients undergoing arteriovenous hemodialysis access

BackgroundPatients undergoing arteriovenous (AV) access creation for hemodialysis often have significant comorbidities. Our goal was to quantify the long-term survival and associated risks factors for long-term mortality in these patients to aid in optimization of goals and expectations. MethodsThe Vascular Implant Surveillance and Interventional Outcomes Network Vascular Quality Initiative Medicare linked data was used to assess long-term survival in the HD registry. Demographics, comorbidities, and interventions were recorded. Because the majority of hemodialysis patients are provided Medicare, Medicare linkage was used to obtain survival data. Multivariable analysis was used to identify independent associations with mortality. ResultsThere were 13,945 AV access patients analyzed including 10,872 (78%) AV fistulas and 3073 (22%) AV grafts. The median age was 67 years and 56% of patients were male. Approximately one-third had a prior AV access and 44.7% had prior tunneled dialysis catheters. Patients receiving an AV fistula, compared with AV grafts, were more often younger, male, White, obese, independently ambulatory, preoperatively living at home, and less often have a prior AV access and tunneled dialysis catheters (P < .05 for all). The 5-year mortality overall was 62.9% with 61.2% for AV fistulas and 68.8% for AV grafts (P < .001). On multivariable analysis for 5 year mortality, nonambulatory status (hazard ratio [HR], 1.67; 95% confidence interval [CI], 1.53-1.83; P < .001), lower extremity access (HR, 1.67; 95% CI, 1.35-2.05; P < .001), human immunodeficiency virus or acquired immunodeficiency syndrome (HR, 1.44; 95% CI, 1.13-1.82; P < .001), White race (HR, 1.43; 95% CI, 1.35-1.51; P < .001), congestive heart failure (HR, 1.33; 95% CI, 1.26-1.41; P < .001), chronic obstructive pulmonary disease (HR, 1.23; 95% CI, 1.15-1.31; P < .001), and AV graft placement (HR, 1.12; 95% CI, 1.02-1.23, P = .016) were most associated with poor survival. Factors associated with improved survival were never smoking (HR, .73; 95% CI, 0.67-0.79; P < .001), prior/quit smoking (HR, .78; 95% CI, 0.72-0.84; P < .001), preoperative home living (HR, .75; 95% CI, 0.68-0.83; P < .001), and hypertension (HR, .89; 95% CI, 0.8-0.99; P = .03). ConclusionsLong-term survival in Medicare patients undergoing AV access creation is poor with nearly two-thirds of patients having died at 5 years. There are many modifiable risk factors that may improve survival in these patients and give an opportunity for transplantation.

Brachial plexus block using only 1% lidocaine to reduce pain during the endovascular treatment of dysfunctional arteriovenous access.

Interventional endovascular treatments of dysfunctional arteriovenous (AV) access for hemodialysis can cause pain and discomfort to the patients. Ultrasound-guided brachial plexus block (BPB) is an alternative regional anesthesia method, but conventional BPB using ropivacaine or bupivacaine may cause long-lasting motor power loss, significantly reducing patient satisfaction. This study aimed to introduce BPB using only 1% lidocaine, which induces sensory loss while minimizing motor block, and evaluate the efficacy and safety of this procedure. This retrospective study was conducted on 277 consecutive patients with dysfunctional AV access requiring percutaneous transluminal angioplasty (PTA). Of these, 174 patients underwent the BPB procedure using 1% lidocaine. Time data were recorded, and the motor strength grade (MRC scale, grade 0-5) was evaluated. Numeric rating pain score (NRPS, grade 0-10) was asked during every PTA, and overall NRPS and satisfaction scores (scale 1-3) were asked after the procedure was completed. Of the 174 patients who received BPB, the success rate was 100%, and there were no significant complications related to BPB. The MRC scale measured at the time when the complete sensory loss was achieved was 1.99 ± 0.63, and that at the point of sensory recovery when the block effect expired was 3.93 ± 0.62, indicating a good grade of motor strength. The average NRPS during PTA in the BPB group was significantly lower than that of the control group without BPB (1.04 ± 2.04vs 6.30 ± 2.71, p < 0.001). The overall satisfaction score was significantly higher in the BPB group than in the control group (2.79 ± 0.50vs 2.00 ± 0.81, p < 0.001). BPB using only 1% lidocaine can induce a sensory block while minimizing the effect on motor function. It can be applied safely in an outpatient clinic setting with relatively higher satisfaction.

Standardized Methodology for Duplex Ultrasound Examination of Arteriovenous Access for Hemodialysis: A Proposal of the French Society of Vascular Medicine and the French-Speaking Society of Vascular Access.

Duplex ultrasound (DUS) is an essential tool for characterizing and monitoring arteriovenous (AV) access for hemodialysis. The aim of the work described here, requested by the French Society of Vascular Medicine in collaboration with the French-Speaking Vascular Access Society, is to propose a standardized methodology for performing and documenting DUS, taking into account the variety of AV access techniques and the problems routinely encountered. A steering committee reviewed the literature and selected the relevant references. A draft was prepared, and all items with missing or conflicting data were submitted to a Delphi consensus. The final document was discussed and approved by all participants. The principles of DUS evaluation of AV access consist of examination of the afferent artery, the anastomosis and the entire venous drainage system. DUS uses B-mode ultrasound, color flow, pulsed wave and power Doppler analysis. DUS can be used in a variety of clinical situations, which can directly influence the methodology of the examination and the interpretation of the results. Blood flow should be assessed as it correlates with the risk of thrombosis. The measurement should be adapted to the different anatomical and hemodynamic conditions encountered. Characterization of stenosis should take into account the residual diameter of the drainage vein and its hemodynamic consequences. Other complications can be assessed with a standardized DUS examination. When performed according to a rigorous methodology, DUS of the AV access allows a comprehensive assessment of its functionality and eliminates the need for further invasive diagnostic procedures.

The Human Acellular Vessel (HAV) as a vascular conduit for infrainguinal arterial bypass.

Autologous vein is the optimal conduit for peripheral arterial bypass surgery, a standard recently highlighted by findings from the BEST-CLI trial. The Human Acellular Vessel is a novel biologic conduit produced using regenerative medicine technologies with structural and mechanical properties like a human blood vessel. Not yet approved by the United States Food and Drug Administration, the Human Acellular Vessel is being studied as an alternative bypass conduit in patients with peripheral arterial disease, vascular injury, and those in need of arteriovenous access for hemodialysis. This report describes and illustrates the technical aspects of intraoperative handling specific to the use of this new and innovative technology.

Characterization of Long-term Survival in Medicare Patients Undergoing Arteriovenous Hemodialysis Access

Characterization of Long-term Survival in Medicare Patients Undergoing Arteriovenous Hemodialysis Access

Preoperative mapping and multidisciplinary team are the key to success of arteriovenous access for hemodialysis

Introduction and objectivesFunctional and durable vascular access is needed for adequate hemodialysis. Arteriovenous fistula is preferred over prosthetic grafts or central venous catheters, but it is associated with high rates of primary failure and maturation failure.Preoperative mapping of arm vessels with color Doppler ultrasound (CDU) has been shown to be helpful in achieving better short and long-term outcomes. Unfortunately, is more time-consuming than a physical examination and requires an experienced examiner and special equipment; some authors defend that CDU should not be part of the routine preoperative assessment.We reported our experience in preoperative vessel mapping using color Doppler ultrasound to purpose a vascular access to the surgical team, surveillance of vascular access, and evaluation of main outcomes (primary failure, maturation failure, and patency). MethodsThis is a single-center retrospective study that includes patients who attended a specific appointment for vascular access planning consultation between January 2019 and December 2021. A nephrologist performed the physical exam and vascular mapping and proposed to the vascular surgeon team a specific type and location of vascular access. Patients were followed until one month after the first hemodialysis through functioning vascular access. ResultsIn this study, 167 patients were evaluated (114 incident patients – chronic kidney disease stage 4 or 5 – and 53 prevalent patients – under hemodialysis through central venous catheter). The vascular accesses proposed by nephrologist were radial-cephalic arteriovenous fistula in 70 patients (41.9%), brachio-cephalic arteriovenous fistula in 50 patients (29.9%), brachio-basilic arteriovenous fistula in 34 patients (20.4%), arteriovenous graft in 8 patients (4.8%) and central venous catheter in 2 patients (1.2%).Vascular access was constructed in 141 patients: distal arteriovenous fistula in 57 patients (40.4%), brachio-cephalic arteriovenous fistula in 54 patients (38.3%), brachio-basilic AVF in 27 patients (19.1%), and arteriovenous graft in 3 patients (2.1%). The created access corresponds to the proposed access in 129 patients (91.5%).Twenty-two (15.6%) primary failures were registered. Distal arteriovenous fistulas and diabetes mellitus were associated with a higher risk of primary failure (OR=3.929 (1.485–10.392), p=0.004; OR=3.867 (1.235–12.113), p=0.014, respectively).The incidence of maturation failure at eight weeks was 4.8%.The primary patency at 6, 12 and 24 months was 76.3%, 70.4% and 49.2%. Primary assisted patency was 84.8% at 6 and 12 months and 81.3% at 24 months. ConclusionsThis study demonstrates that the study of the entire vascular territory performed with color Doppler ultrasound, within a multidisciplinary team of nephrologists and vascular surgeons, is associated with high rates of autologous access and very low rates of primary failure and maturation failure (almost unprecedented in the literature).

The impact of neighborhood social disadvantage on presentation and management of first-time hemodialysis access surgery patients

ObjectivesThe impact of social determinants of health on the presentation, management, and outcomes of patients requiring hemodialysis (HD) arteriovenous (AV) access creation have not been well-characterized. The Area Deprivation Index (ADI) is a validated measure of aggregate community-level social determinants of health disparities experienced by members living within a community. Our goal was to examine the effect of ADI on health outcomes for first-time AV access patients. MethodsWe identified patients who underwent first-time HD access surgery in the Vascular Quality Initiative between July 2011 to May 2022. Patient zip codes were correlated with an ADI quintile, defined as quintile 1 (Q1) to quintile 5 (Q5) from least to most disadvantaged. Patients without ADI were excluded. Preoperative, perioperative, and postoperative outcomes considering ADI were analyzed. ResultsThere were 43,292 patients analyzed. The average age was 63 years, 43% were female, 60% were of White race, 34% were of Black race, 10% were of Hispanic ethnicity, and 85% received autogenous AV access. Patient distribution by ADI quintile was as follows: Q1 (16%), Q2 (18%), Q3 (21%), Q4 (23%), and Q5 (22%). On multivariable analysis, the most disadvantaged quintile (Q5) was associated with lower rates of autogenous AV access creation (OR, 0.82; 95% confidence interval [CI], 0.74-0.90; P < .001), preoperative vein mapping (OR, 0.57; 95% CI, 0.45-0.71; P < .001), access maturation (OR, 0.82; 95% CI, 0.71-0.95; P = .007), and 1-year survival (OR, 0.81; 95% CI, 0.71-0.91; P = .001) compared with Q1. Q5 was associated with higher 1-year intervention rates than Q1 on univariable analysis, but not on multivariable analysis. ConclusionsThe patients undergoing AV access creation who were most socially disadvantaged (Q5) were more likely to experience lower rates of autogenous access creation, obtaining vein mapping, access maturation, and 1-year survival compared with the most socially advantaged (Q1). Improvement in preoperative planning and long-term follow-up may be an opportunity for advancing health equity in this population.

Characterization of Long-term Survival in Medicare Patients Undergoing Arteriovenous Hemodialysis Access

Patients undergoing arteriovenous (AV) access creation for hemodialysis (HD) often have significant comorbidities. Our goal was to quantify the long-term survival and associated risk factors for long-term mortality in these patients to aid in optimization of goals and expectations. The Vascular Implant Surveillance and Interventional Outcomes Network (VISION) Vascular Quality Initiative Medicare–linked data were used to assess long-term survival in the HD registry. Demographics, comorbidities, and interventions were recorded. As the majority of HD patients are provided Medicare, Medicare linkage was used to obtain survival data. Multivariable analysis was used to identify independent associations with mortality. A total of 13,945 AV access patients were analyzed: 10,872 (78%) AV fistulas and 3073 (22%) AV grafts. Patients receiving an AV fistula were more often younger, male, White, obese, independently ambulatory, preoperatively living at home, have fewer comorbidities, and less often have a prior AV access and tunneled dialysis catheters (P < .05 for all). The 5-year mortality overall was 62.9%, with 61.2% for AV fistulas and 68.8% for AV grafts (P < .001). On multivariable analysis, nonambulatory status (hazard ratio [HR]: 1.67, 95% confidence interval [CI]: 1.53-1.83; P < .0001), lower extremity access (HR: 1.67, 95% CI: 1.35-2.05; P < .0001), HIV/AIDS (HR: 1.44, 95% CI: 1.13-1.82; P = .003), White race (HR: 1.43, 95% CI: 1.35-1.51; P < .0001), current smoking (HR: 1.38, 95% CI: 1.27-1.49; P < .0001), congestive heart failure (HR: 1.33, 95% CI: 1.26-1.41; P < .0001), chronic obstructive pulmonary disease (HR: 1.23, 95% CI: 1.15-1.31; P < .0001), and AV graft placement (HR: 1.12, 95% CI: 1.02-1.23; P = .016) were associated with poor survival. Long-term survival in Medicare patients undergoing AV access creation is poor with nearly two-thirds of patients having died at 5 years. Further research focusing on modifiable risk factors in this population is warranted.

Outcomes of operative intervention for ulcers over hemodialysis arteriovenous access.

The native arteriovenous fistula (AVF) is the gold standard for long-term hemodialysis access. When native vein options are exhausted, arteriovenous graft (AVG) becomes the next choice. An ulcer over an AVF or AVG is a serious condition with the potential for life-threatening hemorrhage. This study aims to present our experience with surgical management of ulcers over AVFs or AVGs. Electronic records of 26 patients who underwent 27 consecutive surgical procedures for ulcers over AVFs or AVGs from December 31, 2016 to December 31, 2021 at the Royal Liverpool University Hospital were retrospectively analyzed. The majority were males (14/26, 53.8%) and the median age was 64.5 years. Operative repair was required for 25 ulcers over 24 AVFs and 2 ulcers over 2 AVGs. Ten patients (37%) presented with bleeding. Seventeen (63%) had impending bleeding suggested by a thin soft tissue covering or a false aneurysm at the site of the ulcer. Previous endovascular intervention for fistula outflow stenosis was a significant predictor for presenting with bleeding (p=0.031). All ulcers (27/27, 100%) underwent excision and primary skin closure. Fistula wall defects were directly repaired in 18/27 (66.7%). Four/26 (14.8%) fistulas had to be ligated and 2 (7.4%) had end-to-end re-anastomosis after excision of damaged segments. Three/26 (11.53%) fistulas thrombosed immediately after the intervention. The overall fistula salvage rate was 73.08% (19/26). There was 1 (3.7%) patient mortality due to bleeding from wound breakdown after surgery. An acceptable fistula salvage rate can be expected following surgical repair of ulcers over AVFs and AVGs. A history of previous endovascular interventions for fistula outflow stenosis was a predictor of bleeding from these ulcers.

Effect of Smoking on Outcomes of Arteriovenous Access for Hemodialysis

Effect of Smoking on Outcomes of Arteriovenous Access for Hemodialysis

Evaluation Of The Artegraft Conduit For Lower Extremity Revascularization: Retrospective Analysis Of Outcomes When Used In The Situation Of No Available Autologous Saphenous Vein For Conduit In Lower Extremity Bypass Procedures

Artegraft is a biological conduit made from bovine carotid artery. Over the years, there have been a multitude of studies evaluating the outcomes of Artegraft in arteriovenous access for hemodialysis. There are limited reports on its use in lower extremity revascularization. Use of other biologic grafts such as the umbilical vein graft showed superior outcome compared with other non-biologic grafts in lower extremity bypass. The objective of this paper was to evaluate our experience utilizing Artegraft in lower extremity bypasses when no native venous conduit was available.

Efficacy and Safety of Secondary Procedures for Maintaining Arteriovenous Hemodialysis Access: A Systematic Review and Bayesian Network Meta-Analysis

Randomized trials have compared a variety of different endovascular therapies for patients with a failing arteriovenous (AV) hemodialysis access. However, many clinically relevant therapies have never been compared head-to-head in clinical trials. In the present network meta-analysis (NMA), we evaluated the relative effectiveness of multiple endovascular therapies to maintain AV hemodialysis access according to all available evidence.

Arteriovenous Hemodialysis Access Stenosis Diagnosed by Duplex Doppler Ultrasonography: A Review.

Arteriovenous fistula (AVF) is currently the hemodialysis access with the longest life expectations for the patients. However, even the AVF is at risk for many complications, especially the development of stenosis. The latter can not only lead to inadequate hemodialysis but also lead to AVF thrombosis. Duplex Doppler ultrasonography is a very precise method, in the hands of experienced professionals, for the diagnosis of AVF complications. In this review, we summarize the ultrasound diagnostic criteria of significant stenoses and their indication for procedural therapy.

Ultrasound-Guided Cradle-Like Infiltrative Anesthesia for Percutaneous Transluminal Angioplasty of Stenotic Autogenous Arteriovenous Hemodialysis Access

Percutaneous transluminal angioplasty (PTA) is an effective treatment for autogenous arteriovenous hemodialysis access (AAVA) stenosis; however, it causes pain in most cases. Therefore, safe and effective anesthesia for PTA is required. We introduced a method of ultrasound-guided cradle-like infiltration anesthesia (UCIA) to administer analgesia during PTA. Using ultrasound guidance, 1% lidocaine was injected into the bilateral and inferior perivascular spaces of the stenosis to form a cradle-like region. In this study, 100 consecutive patients were divided into two groups, and the analgesic effect of UCIA was evaluated using a numerical rating scale with non-ultrasound-guided infiltration anesthesia as a control. Meanwhile, we compared the effect of PTA between the two groups with the postoperative internal diameter of the stenosis. The numerical rating scale score was 4.6 ± 1.9 and 2.0 ± 1.6 (P < 0.001) in UCIA group and non-ultrasound-guided infiltration anesthesia group, respectively. The postoperative internal diameter of stenosis was 3.9 ± 0.6 mm and 4.1 ± 0.7 mm (P=0.113); the postoperative AAVA flow volume was 627 ± 176 mL/min and 644 ± 145 mL/min (P=0.600). This study preliminarily showed that UCIA is effective and safe for the analgesia of AAVA PTA.

An Uncommon Cause of Hematemesis in a Patient With End-stage Renal Disease

Question: A 45-year-old man presented with an acute onset of large volume hematemesis associated with worsening facial and neck swelling for the past 6 months. He has a significant past medical history of end-stage renal disease secondary to congenital dysplastic kidneys and has been on hemodialysis for the past 30 years. He has no history of chronic liver disease. Clinical examination revealed diffuse facial and neck edema. Dilated superficial veins were also seen on his upper anterior chest wall. A pulsatile left brachiocephalic arteriovenous fistula was present. The patient was intubated and urgent esophagogastroduodenoscopy was performed. The following bleeding lesion was visualized 25 cm from the incisors (Figure A). What is the diagnosis? Look on page 405 for the answer and see the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI. The patient was suspected to have downhill esophageal varices. The bleeding varix located 25 cm from the incisors was band ligated with successful hemostasis (Figure B). A computed tomographic venography of the thorax was performed, which revealed an occluded right brachiocephalic to superior vena cava stent (white arrow) and a prominent azygos vein (red arrow) (Figure C). The patient underwent a percutaneous central venogram and balloon angioplasty of the occluded right brachiocephalic and superior vena cava stent (Figure D). After the procedure, the patient’s facial and neck swelling diminished rapidly and there were no further episodes of bleeding. Downhill varices, or otherwise known as proximal esophageal varices are most commonly due to superior vena cava obstruction secondary to various etiologies such as malignancy, mediastinal fibrosis, and central venous catheter placement.1Ostler P.J. Clarke D.P. Watkinson A.F. Gaze M.N. Superior vena cava obstruction: a modern management strategy.Clin Oncol (R Coll Radiol). 1997; 9: 83-89Abstract Full Text PDF PubMed Google Scholar Although malignancy is the most common etiology of superior vena cava obstruction, bleeding downhill varices tend to occur more in patients with benign etiologies, such as central venous catheter placement.2Loudin M. Anderson S. Schlansky B. Bleeding 'downhill' esophageal varices associated with benign superior vena cava obstruction: case report and literature review.BMC Gastroenterol. 2016 24; 16: 134Crossref PubMed Scopus (13) Google Scholar This phenomenon may be due to increased venous return and pressure secondary to the underlying arteriovenous access for hemodialysis. The underlying superior vena cava obstruction leads to diversion of venous return through the azygos vein, which in turns causes engorgement of the veins draining the proximal to middle aspect of the esophagus, and causing the development of downhill varices.3Marini T.J. Chughtai K. Nuffer Z. et al.Blood finds a way: pictorial review of thoracic collateral vessels.Insights Imaging. 2019; 10: 63Crossref PubMed Scopus (3) Google Scholar During acute bleeding, endoscopic therapies such as variceal band ligation can be used for hemostasis. However, the mainstay of treatment is to treat and relieve the underlying superior vena cava obstruction. Clinicians should have a high index of suspicion for downhill varices if a patient with end-stage renal disease on hemodialysis presents with upper gastrointestinal bleeding, especially if the patient has a history of central venous catheter placement.

Role of Doppler ultrasonography in the evaluation of hemodialysis arteriovenous access maturation and influencing factors.

The goal of vascular access creation is to achieve a functioning arteriovenous fistula (AVF) or arteriovenous graft (AVG). An autologous fistula has been shown to be superior to AVG or to central venous catheters (CVCs) with lowest rate of re-intervention, but vessel obstruction or immaturity accounts for 20 % to 54% of cases with primary failure of AVF. This review is focused on the factors influencing maturation; indication and timing of preoperative mapping/creation of vascular access; ultrasound parameters for creation AVF/AVG; early postoperative complications following creation of a vascular access; ultrasound determinants of fistula maturation and endovascular intervention in vascular access with maturation failure. However, vascular accesses that fail to develop, have a high incidence of correctable abnormalities, and these need to be promptly recognized by ultrasonography and managed effectively if a high success rate is to be expected. We review approaches to promoting fistula maturation and duplex ultrasonography (DUS) of evaluating vascular access maturation.

Assessment of blood distribution in response to post-surgical steal syndrome: A novel technique based on Thermo-Anatomical Segmentation

The distal ischemic steal syndrome (ISS) is a complication following the construction of an arteriovenous (A-V) access for hemodialysis. The ability to non-invasively monitor changes in skin microcirculation improves both the diagnosis and treatment of vascular diseases. In this study, we propose a novel technique for evaluating the palms' blood distribution following arteriovenous access, based on thermal imaging. Furthermore, we utilize the thermal images to identify typical recovery patterns of patients that underwent this surgery and show that thermal images taken post-surgery reflect the patient's follow-up status. Thermal photographs were taken by a portable thermal camera from both hands before and after the A-V access surgery, and one month following the surgery, from ten dialysis patients. A novel term “Thermo-Anatomical Segmentation”, which enables a functional assessment of palm blood distribution was defined. Based on this segmentation it was shown that the greatest change after surgery was in the most distal region, the fingertips (p < 0.05). In addition, the changes in palm blood distribution in both hands were synchronized, which indicates a bilateral effect. An unsupervised machine learning model revealed two variables that determine the recovery pattern following the surgery: the palms' temperature difference pre- and post-surgery and the post-surgery difference between the treated and untreated hand. Our proposed framework provides a new technique for quantitative assessment of the palm's blood distribution. This technique may improve the clinical treatment of patients with vascular disease, particularly the patient-specific follow-up, in clinics as well as in homecare.

Factors affecting the long term patency of arteriovenous access for hemodialysis: A single center experience

Objective: The objective of the study was to analyze and evaluate the possible factors in the long-term patency of arteriovenous (AV) access for hemodialysis (HD). Materials and Methods: This was a cross-sectional study recruiting patients from January 2019 to December 2019. All patients who have a working HD vascular access, either AV fistula (AVF) or AV graft which has been working for at least 2 years were included and collected demographic data along with other parameters such as timing of creation, interventions, dialysis sessions, and antiplatelet therapy among others. Results: We included 81 patients with AV access patent more than 2 years; 22.5% were aged >65 years, 39.6% were diabetic, 68.5% were hypertensive, and 26.1% had vascular disease. Analysis revealed that the patient factors such as current tobacco usage and side of creation and technical factors such as maturation time, number of dialysis sessions, and single-center dialysis have a significant effect on the patency of the AV access, while the factors such as past tobacco usage, diabetes, hypertension, use of jugular catheter before access creation, and cannulation technique could not establish any statistical effect on the patency of AV access. Conclusion: There is a complex interaction of factors that may affect the patency of an individual AV access. These need to be carefully considered when selecting surgical site or technique, adjuvant treatments, and follow-up protocols for AVFs.