Diagnostic value of color Doppler ultrasonography and MDCT angiography in complications of hemodialysis fistulas and grafts

The Role of Immunosuppressive Therapy in Aneurysmal Degeneration of Hemodialysis Fistulas in Renal Transplant Patients

BACKGROUND

Venous aneurysms are long-term complications of arteriovenous fistula (AVF) for hemodialysis with an estimated incidence rate of around 5-6%. The purpose of our study is to investigate the role of immunosuppressive therapy in the development of AVF aneurysms in renal transplant patients, and to determine whether AVF closure following transplantation is necessary.

METHODS

Forty-six patients with symptomatic venous AVF aneurysms underwent ligation and resection of their fistulas between January 2013 and January 2020. Immunohistochemical expression of CD3, CD4, and CD8 was assessed on the surgical specimens to characterize lymphocytic infiltrate in the aneurysm wall. Patients were subdivided into "Group A"-kidney transplant patients undergoing immunosuppressive therapy which was comprised of 39 patients and "Group B"-patients who had not undergone kidney transplant which was comprised of 7 patients. The 2 groups did not significantly differ in age, sex nor risk factors for aneurysms.

RESULTS

Group A showed a significantly higher aneurysm diameter (P < 0.0001), mean flow (P < 0.0001) and required a longer duration of surgery (P = 0.0007). A CD3+ lymphocytic infiltrate was significantly more common in Group A than in the Group B (90% vs 29%; P < 0.001). No significant differences in localization (adventitia, media or intima) and type (CD4+ vs CD8+) of lymphocytes were found between the 2 groups.

CONCLUSION

AVF venous aneurysms were significantly larger and with a more intense T-lymphocytic infiltrate in patients undergoing immunosuppressive therapy. This finding suggests that immunosuppressive therapy plays a role in aneurysm formation, supporting the need for AVF closure in patients with an estimated low risk of rejection.

The diagnostic value of multi-detector CT angiography for catheter-related central venous stenosis in hemodialysis patients

The objective is to compare Multi-detector CT angiography (MDCTA) and digital subtraction angiography (DSA) in diagnosing hemodialysis catheter related-central venous stenosis (CVS). During a period of 6 years, hemodialysis patients with suspected catheter related-CVS who received both MDCTA and DSA were retrospectively enrolled. We analyzed the sensitivity, specificity, accuracy, Cohen's kappa coefficient (κ) and other diagnostic parameters for MDCTA compared to DSA. A total of 1533 vascular segments in 219 patients were analyzed. Among the 280 lesions identified by DSA, 156 were correctly identified by MDCTA. There were 124 false negative and 41 false positive diagnoses. MDCTA had a high specificity (96.73%) but a low sensitivity (55.71%), with a moderate inter-test agreement (κ = 0.5930). In stratified analyses of vascular segments, the specificities of MDCTA were 89.93% (superior vena cava), 98.95% (left brachiocephalic vein), 95.33% (right brachiocephalic vein), 99.53% (left subclavian vein), 97.61% (right subclavian vein), 97.13% (left internal jugular vein), and 95.86% (right internal jugular vein), while the sensitivities were 90.00%, 65.52%, 66.67%, 87.50%, 40.00%, 20.00% and 8.11%, respectively. Good to excellent inter-test agreement was observed for the superior vena cava (κ = 0.7870), left brachiocephalic vein (κ = 0.7300), right brachiocephalic vein (κ = 0.6610), and left subclavian vein (κ = 0.8700) compared with poor to low agreement for the right subclavian vein (κ = 0.3950), left internal jugular vein (κ = 0.1890), and right internal jugular vein (κ = 0.0500). MDCTA had a high specificity in diagnosing hemodialysis catheter related-CVS. Its sensitivity varied by central venous segments, with better performance in superior vena cava and brachiocephalic veins.

Angiography and phlebography in a hemodialysis population: A retrospective analysis of interventional results

OBJECTIVE

To clarify the reasons and beneficial effects and duration of arteriovenous fistula patency after radiological interventions in arteriovenous fistula. The patients investigated were referred due to arteriovenous fistula access flow problems.

MATERIAL AND METHODS

In 174 patients, 522 radiological investigations and endovascular treatments such as percutaneous transluminal angioplasty were analyzed, retrospectively. All investigations were performed due to clinical suspicion of impaired arteriovenous fistula function.

RESULTS

Arterial stenosis was significantly more frequent among patients with diabetic nephropathy (p < 0.001) and interstitial nephritis (p < 0.001). According to the venous stenosis, the diagnosis did not affect the frequency (p = 0.22) or the degree (p = 0.39) of stenosis. The degree of stenosis prior to percutaneous transluminal angioplasty correlated significantly with the degree of remaining stenosis after intervention (p < 0.001). Of the 174 patients, 123 (71%) performed a total of 318 investigations including percutaneous transluminal angioplasty. Repeated percutaneous transluminal angioplasty was performed significantly more often in patients with diabetic nephropathy. The median times to the first percutaneous transluminal angioplasty and to the subsequent percutaneous transluminal angioplasties were 9.5 and 5 months, respectively. Arteriovenous fistula in patients with diabetic nephropathy performed similar to most other diagnoses, although performing more percutaneous transluminal angioplasty/patient than most other diagnoses.

CONCLUSION

Many patients could maintain long-term patency of arteriovenous fistula, including those with diabetic nephropathy, with repeated interventions; this motivates a closer follow-up for these patients. Clinically significant stenosis should be dilated as meticulously and as soon as possible. Occlusions of the arteriovenous fistula in most instances can be successfully thrombolyzed or dilated upon early diagnosis.

Value of duplex Doppler ultrasonography for the evaluation of dysfunctional hemodialysis access arteriovenous fistulas prior to endovascular interventions

PURPOSE

To demonstrate accuracy of duplex Doppler ultrasonography (DUS) for the evaluation of native-vein arteriovenous fistula (AVF) dysfunction in end-stage renal disease patients.

METHODS

This retrospective study included 60 patients with dysfunctioning native-vein AVF evaluated with DUS and digital subtraction angiography (DSA) whose results were compared for detection, identification, and localization of AVF lesions. We calculated sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of DUS and evaluated the agreement between DUS and DSA by the Cohen's kappa coefficient (κ).

RESULTS

DUS identified correctly 123 of 130 lesions (sensitivity 94.6%, specificity 97.5%, PPV 98.4%, NPV 92%, accuracy of 95.7%). DUS localized correctly 123 of 130 lesions (sensitivity 94.6%, specificity 98.4%, PPV 98.4%, NPV 94.6%, accuracy 96.4%). The κ value was 0.9120 for detection of all lesions (almost perfect agreement).

CONCLUSION

DUS is a reliable method for the initial evaluation of dysfunctional AVFs, with high sensitivity for detecting and correctly localizing circuit problems.

Spanish Clinical Guidelines on Vascular Access for Haemodialysis

Vascular access for haemodialysis is key in renal patients both due to its associated morbidity and mortality and due to its impact on quality of life. The process, from the creation and maintenance of vascular access to the treatment of its complications, represents a challenge when it comes to decision-making, due to the complexity of the existing disease and the diversity of the specialities involved. With a view to finding a common approach, the Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology [S.E.N.], vascular surgery [SEACV], vascular and interventional radiology [SERAM-SERVEI], infectious diseases [SEIMC] and nephrology nursing [SEDEN]), along with the methodological support of the Cochrane Center, has updated the Guidelines on Vascular Access for Haemodialysis, published in 2005. These guidelines maintain a similar structure, in that they review the evidence without compromising the educational aspects. However, on one hand, they provide an update to methodology development following the guidelines of the GRADE system in order to translate this systematic review of evidence into recommendations that facilitate decision-making in routine clinical practice, and, on the other hand, the guidelines establish quality indicators which make it possible to monitor the quality of healthcare.

Dialysis arteriovenous access monitoring and surveillance according to the 2017 Spanish Guidelines

The Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology (S.E.N.), vascular surgery (SEACV), interventional radiology (SERAM-SERVEI), infectious diseases (SEIMC), and nephrology nursing (SEDEN)), along with the methodological support of the Iberoamerican Cochrane Centre, has developed the Spanish Clinical Guidelines on Vascular Access for Hemodialysis. This article summarizes the main issues from the guideline's chapter entitled "Monitoring and surveillance of arteriovenous access." We will analyze the current evidence on conflicting topics such as the value of the flow-based screening methods for the arteriovenous access surveillance or the role of Doppler ultrasound as the imaging exploration to confirm suspected stenosis. In addition, the concept of significant stenosis and the criteria to perform the elective intervention for stenosis were reviewed. The adoption of these guidelines will hopefully translate into a reduced risk of thrombosis and increased patency rates for both arteriovenous fistulas and grafts.

Imaging of Patients with Complex Hemodialysis Arterio-Venous Fistulas using Time-Resolved Dynamic CT Angiography: Comparison with Duplex Ultrasound

To evaluate the feasibility and potential on therapy management of time-resolved dynamic computed tomography angiography (dCTA) in patients with forearm arterio-venous fistula (AVF)/arterio-venous grafts (AVG). Thirty-five patients with complex failing forearm AVF/AVGs were examined with ultrasound and a dCTA protocol. Diagnosis and therapy management was evaluated versus duplex ultrasound (DUS) in three different readouts: 1. all dCTA datasets; 2. one arterial phase of the dCTA dataset; 3. one arterial and one venous dataset out of the dCTA dataset. All reads were performed >30 days apart from each other. Using all data of the dCTA examination, 20 patients were classified as having a stenosis >50%, 12 high-shunt flow, 11 partial thrombosis, 5 venous aneurysms and 5 complete thrombosis of their AVF/AVG grafts. This lead to 13 additional pathologic findings not visible on DUS and reclassification as normal in one patient with suspected AVF stenosis and complete thrombus on DUS. These additional findings lead to a direct change of therapeutic management in 8 patients. Compared to readout 1 (53 pathologies), readout number 2 and 3 revealed only 33 and 41 pathologies, respectively. dCTA provides additional information, improving diagnostic confidence and leading to changes in therapy management when compared to DUS alone.

Venous aneurysm complicating arteriovenous fistula access and matrix metalloproteinases

Introduction

An arteriovenous fistula (AVF) for placed for hemodialysis may be burdened by one particular complication—the formation of a venous aneurysm. It has been shown that matrix metalloproteinases (MMPs) and neutrophil gelatinase-associated lipocalin (NGAL) could represent markers of disease in both venous and arterial vessels.

Materials and methods

This case study reports a rare case of enormous venous aneurysm-correlated MMP and NGAL levels in a woman with an AVF.

Results

Significantly higher levels of plasma MMP-1, MMP-8, MMP-9, and NGAL were detected in this patient during aneurysmal evaluation before the surgery; these levels significantly decreased 1, 3 and 6 months after surgery.

Conclusion

MMP and NGAL levels could represent a marker of aneurysmal disease, and their plasma evaluation could help physicians to stratify the risk of complications in patients with an AVF.

Radiological Assessment of Vascular access in Haemodialysis Patients

Clinical examination is still the most important diagnostic tool and duplex ultrasonography is the imaging method of first choice. Radiological assessment of vascular access for haemodialysis includes preoperative analysis of vessel anatomy and postoperative surveillance for access maturation as well as diagnosis in vascular access insufficiency. Compared to ultrasonography digital subtraction angiography is superior for the evaluation of the central veins and allows diagnosis and treatment in one session. Computed tomography should only be used in patients with inconclusive ultrasonography results, for example, for the assessment of the central veins and visualization of the vascular tree. Gadolinium-enhanced magnetic resonance imaging is no longer recommended in dialysis patients, because it may trigger nephrogenic systemic fibrosis. In patients with a history of previous central venous catheters additional preoperative imaging of the central veins should be performed. In this article we review the different radiological imaging methods for preoperative assessment and suspected vascular access dysfunction.

Diagnostic accuracy of computer tomography angiography and magnetic resonance angiography in the stenosis detection of autologuous hemodialysis access: a meta-analysis

Purpose

To compare the diagnostic performances of computer tomography angiography (CTA) and magnetic resonance angiography (MRA) for detection and assessment of stenosis in patients with autologuous hemodialysis access.

Materials and Methods

Search of PubMed, MEDLINE, EMBASE and Cochrane Library database from January 1984 to May 2013 for studies comparing CTA or MRA with DSA or surgery for autologuous hemodialysis access. Eligible studies were in English language, aimed to detect more than 50% stenosis or occlusion of autologuous vascular access in hemodialysis patients with CTA and MRA technology and provided sufficient data about diagnosis performance. Methodological quality was assessed by the Quality Assessment of Diagnostic Studies (QUADAS) instrument. Sensitivities (SEN), specificities (SPE), positive likelihood ratio (PLR), negative likelihood values (NLR), diagnostic odds ratio (DOR) and areas under the receiver operator characteristic curve (AUC) were pooled statistically. Potential threshold effect, heterogeneity and publication bias was evaluated. The clinical utility of CTA and MRA in detection of stenosis was also investigated.

Result

Sixteen eligible studies were included, with a total of 500 patients. Both CTA and MRA were accurate modality (sensitivity, 96.2% and 95.4%, respectively; specificity, 97.1 and 96.1%, respectively; DOR [diagnostic odds ratio], 393.69 and 211.47, respectively) for hemodialysis vascular access. No significant difference was detected between the diagnostic performance of CTA (AUC, 0.988) and MRA (AUC, 0.982). Meta-regression analyses and subgroup analyses revealed no statistical difference. The Deek’s funnel plots suggested a publication bias.

Conclusion

Diagnostic performance of CTA and MRA for detecting stenosis of hemodialysis vascular access had no statistical difference. Both techniques may function as an alternative or an important complement to conventional digital subtraction angiography (DSA) and may be able to help guide medical management.