1
|
Bae M, Chung SW, Lee CW, Huh U, Jin M, Jeon CH. Skin perfusion pressure for predicting access-related hand ischemia following arteriovenous fistula surgery based on the brachial artery. J Vasc Access 2021; 23:383-389. [PMID: 33586510 DOI: 10.1177/1129729821993985] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Access-related hand ischemia (ARHI) is a major complication of arteriovenous fistula (AVF). This study aimed to assess the predictive efficacy of skin perfusion pressure (SPP) measurement for ARHI by examining the relationship between SPP and ARHI development and progression after AVF surgery. METHODS Twenty-five patients (16 men and 9 women) who underwent AVF surgery based on the brachial artery between January 2018 and December 2018 were included. The pre- and postoperative SPP values were measured on the day of surgery. ARHI occurrence and severity were measured within 3 days and at 6 months after surgery. Receiver operating characteristic curve analysis was used to evaluate the prediction model of ARHI, and the cutoff points for the calculated coefficients were determined. RESULTS There was a significant correlation between the occurrence of immediate ARHI and the SPP gradient (p = 0.024). An SPP gradient value >50 mmHg had sensitivity and specificity values of 53.85% and 91.67%, respectively, in predicting the occurrence of immediate ARHI. A postoperative SPP <48 mmHg was significantly correlated with the occurrence of 6-month ARHI (p = 0.005), with sensitivity and specificity values of 71.43% and 83.33%, respectively. CONCLUSION The SPP gradient and postoperative SPP values may be effective clinical predictors of ARHI occurring immediately and 6 months after surgery, respectively, with high specificity. These findings could allow clinicians to diagnose and begin early interventions to help prevent ischemic tissue damage in hemodialysis patients following AVF surgery.
Collapse
Affiliation(s)
- Miju Bae
- Department of Thoracic and Cardiovascular Surgery, Pusan National University Hospital, Busan, Republic of Korea.,Medical Research Institute, Pusan National University Hospital, Busan, Republic of Korea
| | - Sung Woon Chung
- Department of Thoracic and Cardiovascular Surgery, Pusan National University Hospital, Busan, Republic of Korea.,Medical Research Institute, Pusan National University Hospital, Busan, Republic of Korea
| | - Chung Won Lee
- Department of Thoracic and Cardiovascular Surgery, Pusan National University Hospital, Busan, Republic of Korea
| | - Up Huh
- Department of Thoracic and Cardiovascular Surgery, Pusan National University Hospital, Busan, Republic of Korea
| | - Moran Jin
- Department of Thoracic and Cardiovascular Surgery, Pusan National University Hospital, Busan, Republic of Korea
| | - Chang Ho Jeon
- Department of Radiology, Pusan National University Hospital, Busan, Republic of Korea
| |
Collapse
|
2
|
Lok CE, Huber TS, Lee T, Shenoy S, Yevzlin AS, Abreo K, Allon M, Asif A, Astor BC, Glickman MH, Graham J, Moist LM, Rajan DK, Roberts C, Vachharajani TJ, Valentini RP. KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update. Am J Kidney Dis 2020; 75:S1-S164. [PMID: 32778223 DOI: 10.1053/j.ajkd.2019.12.001] [Citation(s) in RCA: 964] [Impact Index Per Article: 241.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 12/09/2019] [Indexed: 02/07/2023]
Abstract
The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for hemodialysis vascular access since 1996. Since the last update in 2006, there has been a great accumulation of new evidence and sophistication in the guidelines process. The 2019 update to the KDOQI Clinical Practice Guideline for Vascular Access is a comprehensive document intended to assist multidisciplinary practitioners care for chronic kidney disease patients and their vascular access. New topics include the end-stage kidney disease "Life-Plan" and related concepts, guidance on vascular access choice, new targets for arteriovenous access (fistulas and grafts) and central venous catheters, management of specific complications, and renewed approaches to some older topics. Appraisal of the quality of the evidence was independently conducted by using a Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, and interpretation and application followed the GRADE Evidence to Decision frameworks. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.
Collapse
|
3
|
Kordzadeh A, Parsa AD. A systematic review of distal revascularization and interval ligation for the treatment of vascular access-induced ischemia. J Vasc Surg 2019; 70:1364-1373. [PMID: 31153703 DOI: 10.1016/j.jvs.2019.02.060] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 02/05/2019] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Vascular access-induced ischemia remains a rare but significant complication of arteriovenous fistulas. Distal revascularization and interval ligation (DRIL) is one form of treatment. However, its collated efficacy through a systematic review is yet to be established. METHODS An electronic and systematic search of the literature in MEDLINE, Cumulative Index to Nursing and Allied Health Literature, Embase, and Cochrane Library from 1966 to 2017 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was conducted. Quality assessment of the articles was performed using the Oxford Critical Appraisal Skills Programme, and the recommendation for practice was examined through the National Institute for Health and Care Excellence. Data of treated cases, success, time to ischemia, follow-up, age, sex, diabetes mellitus, fistula type, conduit type, and grade of ischemia were extracted and subjected to a pooled variance-weighted random-effects model. RESULTS Twenty-two studies (n = 459 individuals) were subjected to DRIL. Time to ischemia was 196 days (interquartile range, 30-600 days). Ischemia grade 3/4 (52%) was the most common presentation. The overall success (grades 1-4) was 81% (95% confidence interval, 80.9%-82.5%) during a mean and median follow-up of 22.2 months (interquartile range, 1-60 months) and 18 months, respectively. The conduit of choice was the great saphenous vein (n = 300/459 [65%]), and bypass thrombosis was highest in the polytetrafluoroethylene group (n = 19/44 [43%]). CONCLUSIONS DRIL with adequate long-term outcomes is an effective technique for the treatment of vascular access-induced ischemia.
Collapse
Affiliation(s)
- Ali Kordzadeh
- Department of Vascular, Endovascular and Renal Access, Broomfield Hospital, Mid Essex Hospital Service NHS Trust, Essex, United Kingdom; Faculty of Medical Sciences, Anglia Ruskin University, Cambridge, United Kingdom.
| | - Ali Davod Parsa
- Faculty of Medical Sciences, Anglia Ruskin University, Cambridge, United Kingdom
| |
Collapse
|
4
|
Schmidli J, Widmer MK, Basile C, de Donato G, Gallieni M, Gibbons CP, Haage P, Hamilton G, Hedin U, Kamper L, Lazarides MK, Lindsey B, Mestres G, Pegoraro M, Roy J, Setacci C, Shemesh D, Tordoir JH, van Loon M, ESVS Guidelines Committee, Kolh P, de Borst GJ, Chakfe N, Debus S, Hinchliffe R, Kakkos S, Koncar I, Lindholt J, Naylor R, Vega de Ceniga M, Vermassen F, Verzini F, ESVS Guidelines Reviewers, Mohaupt M, Ricco JB, Roca-Tey R. Editor's Choice – Vascular Access: 2018 Clinical Practice Guidelines of the European Society for Vascular Surgery (ESVS). Eur J Vasc Endovasc Surg 2018; 55:757-818. [DOI: 10.1016/j.ejvs.2018.02.001] [Citation(s) in RCA: 346] [Impact Index Per Article: 57.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
5
|
Henriksson AE, Bergqvist D. Steal Syndrome of the Hemodialysis Vascular Access: Diagnosis and Treatment. J Vasc Access 2018; 5:62-8. [PMID: 16596543 DOI: 10.1177/112972980400500204] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Purpose Steal syndrome is an uncommon but serious condition of arterial insufficiency distal to a permanent hemodialysis fistula. The management of the condition is a great challenge to the surgeon because of the conflicting goals of preserving the fistula and treat the ischemia. In this review the purpose was to analyze the clinical problem and treatment possibilities. Methods Medline and Embase databases were searched for studies relevant to diagnosis and management of steal syndrome of the hemodialysis vascular access. Results The diagnosis of steal syndrome is largely based on clinical features and non-invasive studies. In same cases angiography may be necessary to find out the real causes of the steal syndrome. The cause is usually high fistula flow but other causes as steal phenomenon, inflow, outflow or anastomotic stenosis have to be considered and even combination of causes. The main treatment options are some form of flow reducing procedure or the distal revascularization interval ligation method. In some cases simple distal arterial ligation is the method of choice. Furthermore, in some patients a stenosis has to be treated as the first treatment option. Conclusion For an appropriate treatment of a steal syndrome a careful analysis of the cause is important.
Collapse
Affiliation(s)
- A E Henriksson
- Department of Surgery, Sundsvall County Hospital, Sweden.
| | | |
Collapse
|
6
|
Arteriovenous access ischemic steal (AVAIS) in haemodialysis: a consensus from the Charing Cross Vascular Access Masterclass 2016. J Vasc Access 2016; 18:3-12. [DOI: 10.5301/jva.5000621] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2016] [Indexed: 12/28/2022] Open
Abstract
Arteriovenous access ischaemic steal (AVAIS) is a serious and not infrequent complication of vascular access. Pathophysiology is key to diagnosis, investigation and management. Ischaemia distal to an AV access is due to multiple factors. Clinical steal is not simply blood diversion but pressure changes within the adapted vasculature with distal hypoperfusion and resultant poor perfusion pressures in the distal extremity. Reversal of flow within the artery distal to the AV access may be seen but this is not associated with ischaemia in most cases. Terminology is varied and it is suggested that arteriovenous access ischemic steal (AVAIS) is the preferred term. In all cases AVAIS should be carefully classified on clinical symptoms as these determine management options and allow standardisation for studies. Diabetes and peripheral arterial occlusive disease are risk factors but a ‘high risk patient’ profile is not clear and definitive vascular access should not be automatically avoided in these patient groups. Multiple treatment modalities have been described and their use should be directed by appropriate assessment, investigation and treatment of the underlying pathophysiology. Comparison of treatment options is difficult as published studies are heavily biased. Whilst no single technique is suitable for all cases of AVAIS there are some that suit particular scenarios and mild AVAIS may benefit from observation whilst more severe steal mandates surgical intervention.
Collapse
|
7
|
|
8
|
Huber TS, Larive B, Imrey PB, Radeva MK, Kaufman JM, Kraiss LW, Farber AM, Berceli SA. Access-related hand ischemia and the Hemodialysis Fistula Maturation Study. J Vasc Surg 2016; 64:1050-1058.e1. [PMID: 27478007 DOI: 10.1016/j.jvs.2016.03.449] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 03/23/2016] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Access-related hand ischemia (ARHI) is a major complication after hemodialysis access construction. This study was designed to prospectively describe its incidence, predictors, interventions, and associated access maturation. METHODS The Hemodialysis Fistula Maturation Study is a multicenter prospective cohort study designed to identify predictors of autogenous arteriovenous access (arteriovenous fistula [AVF]) maturation. Symptoms and interventions for ARHI were documented, and participants who received interventions for ARHI were compared with other participants using a nested case-control design. Associations of ARHI with clinical, ultrasound, vascular function, and vein histologic variables were each individually evaluated using conditional logistic regression; the association with maturation was assessed by relative risk, Pearson χ(2) test, and multiple logistic regression. RESULTS The study cohort included 602 participants with median follow-up of 2.1 years (10th-90th percentiles, 0.7-3.5 years). Mean age was 55.1 ± 13.4 (standard deviation) years; the majority were male (70%), white (47%), diabetic (59%), smokers (55%), and on dialysis (64%) and underwent an upper arm AVF (76%). Symptoms of ARHI occurred in 45 (7%) participants, and intervention was required in 26 (4%). Interventions included distal revascularization with interval ligation (13), ligation (7), banding (4), revision using distal inflow (1), and proximalization of arterial inflow (1). Interventions were performed ≤7 days after AVF creation in 4 participants (15%), between 8 and 30 days in 6 (23%), and >30 days in 16 (63%). Female gender (odds ratio, 3.17; 95% confidence interval, 1.27-7.91; P = .013), diabetes (13.62 [1.81-102.4]; P = .011), coronary artery disease (2.60 [1.03-6.58]; P = .044), higher preoperative venous capacitance (per %/10 mm Hg, 2.76 [1.07-6.52]; P = .021), and maximum venous outflow slope (per [mL/100 mL/min]/10 mm Hg, 1.13 [1.03-1.25]; P = .011) were significantly associated with interventions; a lower carotid-femoral pulse wave velocity and the outflow vein diameter in the early postoperative period (days 0-3) approached significance (P < .10). Intervention for ARHI was not associated with AVF maturation failure (unadjusted risk ratio, 1.18 [0.69-2.04], P = .56; adjusted odds ratio, 0.97 [0.41-2.31], P = .95). CONCLUSIONS Remedial intervention for ARHI after AVF construction is uncommon. Diabetes, female gender, capacitant outflow veins, and coronary artery disease are all associated with an increased risk of intervention. These higher risk patients should be counseled preoperatively, their operative plans should be designed to reduce the risk of hand ischemia, and they should be observed closely.
Collapse
Affiliation(s)
- Thomas S Huber
- Division of Vascular Surgery, University of Florida College of Medicine, Gainesville, Fla.
| | - Brett Larive
- Department of Quantitative Health Sciences, Learner Research Institute, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio
| | - Peter B Imrey
- Department of Quantitative Health Sciences, Learner Research Institute, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio
| | - Milena K Radeva
- Department of Quantitative Health Sciences, Learner Research Institute, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio
| | - James M Kaufman
- Division of Nephrology, VA New York Harbor Healthcare System and Division of Nephrology, New York University School of Medicine, New York, NY
| | - Larry W Kraiss
- Division of Vascular Surgery, University of Utah, Salt Lake City, Utah
| | - Alik M Farber
- Division of Vascular and Endovascular Surgery, Boston Medical Center, Boston, Mass
| | - Scott A Berceli
- Division of Vascular Surgery, University of Florida College of Medicine, Gainesville, Fla
| | | |
Collapse
|
9
|
Distal Radial Artery Embolization: An Alternative Approach towards Access Preservation and Limb Salvage in Radiocephalic Arteriovenous Fistulae Complicated by Steal Syndrome. Ann Vasc Surg 2016; 33:131.e1-5. [DOI: 10.1016/j.avsg.2016.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 02/11/2016] [Accepted: 02/11/2016] [Indexed: 11/19/2022]
|
10
|
Leake AE, Winger DG, Leers SA, Gupta N, Dillavou ED. Management and outcomes of dialysis access-associated steal syndrome. J Vasc Surg 2015; 61:754-60. [DOI: 10.1016/j.jvs.2014.10.038] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 10/16/2014] [Indexed: 10/24/2022]
|
11
|
Preoperative Duplex Examination in Patients with Dialysis Access-related Hand Ischemia: Indication for Distal Radial Artery Ligation. J Vasc Access 2015; 16:255-7. [DOI: 10.5301/jva.5000341] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2014] [Indexed: 11/20/2022] Open
Abstract
Purpose To demonstrate that treatment with distal radial artery ligation (DRAL), based on preoperative evaluation with duplex ultrasound, is effective for correction of hand ischemia related to distal radiocephalic arteriovenous fistula (AVF). Methods Two patients with symptoms of hemodialysis access-induced distal ischemia (HAIDI) related to radiocephalic AVF at wrist (necrotic lesion of fingers, pain at rest and loss of sensory function) were studied with preoperative duplex examination. Color Doppler ultrasound (CDU) showed low-normal flux (700 and 500 mL/min respectively), retrograde flow in the DRA and increased digital perfusion after manual occlusion of DRA. They were both treated by ligation of the DRA. Results Both patients had immediate improvement of ischemic symptoms. Reversed DRA flow disappeared and peripheral flow ameliorated. Postoperative AVF flow was 500 and 350 mL/min, stable at 16 and 8 months of follow-up, respectively. Conclusions Preoperative CDU examination, simulating reversed DRA flow interruption, seems to be an effective tool to predict the success of DRAL procedure.
Collapse
|
12
|
|
13
|
Samaha A, Salman L, Asif A. Arterial Angioplasty to Treat Hand Ischemia in a Radial-Cephalic Fistula. Semin Dial 2009; 22:561-3. [DOI: 10.1111/j.1525-139x.2009.00625.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
14
|
Raynaud A, Novelli L, Rovani X, Carreres T, Bourquelot P, Hermelin A, Angel C, Beyssen B. Radiocephalic Fistula Complicated by Distal Ischemia: Treatment by Ulnar Artery Dilatation. Cardiovasc Intervent Radiol 2009; 33:223-5. [DOI: 10.1007/s00270-009-9645-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2009] [Revised: 06/04/2009] [Accepted: 06/22/2009] [Indexed: 11/30/2022]
|
15
|
Low-flow maturation failure of distal accesses: Treatment by angioplasty of forearm arteries. J Vasc Surg 2009; 49:995-9. [DOI: 10.1016/j.jvs.2008.10.061] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Revised: 10/24/2008] [Accepted: 10/27/2008] [Indexed: 11/18/2022]
|
16
|
Plumb TJ, Lynch TG, Adelson AB. Treatment of steal syndrome in a distal radiocephalic arteriovenous fistula using intravascular coil embolization. J Vasc Surg 2008; 47:457-9. [DOI: 10.1016/j.jvs.2007.08.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Revised: 07/27/2007] [Accepted: 08/06/2007] [Indexed: 10/22/2022]
|
17
|
Abstract
Primary vascular access is usually achievable by a distal autogenous arterio-venous fistula (AVF). This article describes the approach to vascular access planning, the usual surgical options and the factors affecting patency.
Collapse
|
18
|
Mwipatayi BP, Bowles T, Balakrishnan S, Callaghan J, Haluszkiewicz E, Sieunarine K. Ischemic Steal Syndrome: A Case Series and Review of Current Management. ACTA ACUST UNITED AC 2006; 63:130-5. [PMID: 16520116 DOI: 10.1016/j.cursur.2005.04.017] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Currently over 5000 patients are receiving hemodialysis in Australia, which is an increase by approximately 7% each year. Distal ischemia secondary to the steal syndrome (ISS) is an uncommon but recognized complication. Several methods are now available to manage this problem including ligation, banding, and distal revascularization with interval ligation (DRIL). The aim of this report is to review the experience of the authors on this complication and its management at Royal Perth Hospital. METHODS The Vascular Physiology Laboratory Database was used to identify those patients referred for investigation of ISS. Data were collected retrospectively from these patients' files concerning their demographics, graft particulars, and type of interventional procedure. Patients were then recalled to assess long-term patency and current venous access and for postoperative vascular studies. RESULTS Eighteen people were identified with ischemic symptoms. The mean age was 66 (range, 44 to 82). Fourteen (77.8%) were men, and 15 (83.3%) were diabetic. Renal failure was secondary to diabetes in 8 patients, hypertension in 3, and a combination of both in 7 patients. Intervention was via the DRIL procedure in 12, ligation in 5, and banding in 1. One patient underwent angioplasty of the ulnar artery before DRIL. At follow-up (between 1 and 12 months), all DRIL bypass were patents. The 5 ligated patients all improved, and the patient who underwent banding thrombosed their graft. CONCLUSION The DRIL procedure should be considered the standard operation to manage ISS in that it manages the ischemia while maintaining the functional fistula. It is, however, still necessary to ligate some fistulae and seek alternative access. There are still no preoperative indicators as to who will suffer ISS.
Collapse
Affiliation(s)
- B P Mwipatayi
- Department of Vascular Surgery, Royal Perth Hospital, Perth, Western Australia.
| | | | | | | | | | | |
Collapse
|
19
|
Hunter ID, Calder FR, Quan G, Chemla ES. Vascular steal syndrome occurring 20 years after surgical arteriovenous fistula formation: an unusual cause of loss of hand function. ACTA ACUST UNITED AC 2004; 57:593-4. [PMID: 15308418 DOI: 10.1016/j.bjps.2004.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
20
|
Ramuzat A, How TV, Bakran A. Steal phenomenon in radiocephalic arteriovenous fistula. In vitro haemodynamic and electrical resistance simulation studies. Eur J Vasc Endovasc Surg 2003; 25:246-53. [PMID: 12623337 DOI: 10.1053/ejvs.2002.1842] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE steal phenomenon following an arteriovenous fistula (AVF) creation is characterised by retrograde flow in the artery segment distal to the anastomosis and occurs in the majority of patients with radiocephalic AVF although this rarely leads to distal ischaemia. To investigate the local haemodynamics after the creation of an AVF, a simple electrical resistance model which assumes time-independent flow was used. The applicability of this model to pulsatile flow conditions was verified using an in vitro flow circuit. The effects of stenoses in various artery segments were also investigated. DESIGN OF THE STUDY the electrical analogue model consists of a pressure source, constant resistances that represent the resistance to flow of various arterial segments and the fistula. The stenosis was modelled by a resistor and a non-linear term is simulated by a current-controlled voltage source. In vitro experiments were performed in pulsatile and steady flow and the results were compared with electrical simulations. The effects of fistula flow and the presence and severity of a stenosis on flow distribution, particularly the direction of flow in the distal radial artery and flow into the hand were assessed. RESULTS steady and pulsatile time-averaged flows measured in vitro compared well with the results of electrical circuit simulations for cases without a stenosis. When a stenosis was present comparisons were made only in steady flow and these show good agreement for stenoses of 75% area reduction. The direction of flow in the distal radial artery was antegrade (towards the hand) at low fistula flow and became retrograde as fistula flow increased. The presence of a severe stenosis in the brachial artery was found to have the strongest influence on flow to the hand. CONCLUSIONS an electrical resistance model of a radiocephalic AVF has been validated with an in vitro pulsatile flow circuit. One of the benefits of this model is that it can be easily analysed using standard circuit simulation software. The model also provide insights into the possible haemodynamics consequences of creating an AVF with or without the presence of a stenosis in the arterial segments.
Collapse
Affiliation(s)
- A Ramuzat
- Department of Clinical Engineering, University of Liverpool, UK
| | | | | |
Collapse
|