Ultrasound evaluation of access complications: Thrombosis, aneurysms, pseudoaneurysms and infections

Vascular Ultrasound

Vascular point-of-care ultrasound is a useful tool for emergency department (ED) clinicians to evaluate lower extremity pain and swelling. It can quickly and safely detect deep vein thrombosis, a serious condition that can lead to pulmonary embolism and post-thrombotic syndrome as well as diagnose pseudoaneurysm, hematoma, and acute arterial occlusion, a vascular emergency that requires urgent surgical intervention. Point-of-Care Ultrasound can be a useful tool for the evaluation of ED patients with vascular emergencies.

Arterio-Venous Fistula Calcifications-Risk Factors and Clinical Relevance

(1) Background: Arterio-venous fistulas (AVFs) are considered the gold-standard vascular access (VA) in patients on maintenance hemodialysis (HD) therapy. AVF calcifications represent a less studied VA related complication, even though HD patients are at a higher risk for extraosseous calcifications. The aim of this study is to assess the prevalence and risk factors of AVF calcifications, as well as the 5-year impact on AVF functionality and on overall mortality. (2) Methods: We conducted a 5-year prospective study including 161 patients on maintenance HD therapy. At baseline, we collected data related to VA history, comorbidities, demographics, subjective global assessment scale (SGA), and biochemical parameters. All patients underwent a complete AVF ultrasound and we recorded AVF blood flow and the presence of AVF calcifications, stenoses, and aneurysms. (3) Results: In our study, we found an AVF calcification prevalence of 39%. In a univariate analysis, we found that patients with AVF calcifications were associated with other AVF complications as well (stenoses, aneurysms), had longer AVF and HD vintage, as well as higher serum calcium and PTH values. In a multivariate analysis, we found that patients with a longer HD vintage and higher calcium values were independently associated with AVF calcifications. AVF calcifications did not affect 5-year fistula patency, nor were they associated with a higher mortality risk in our group of patients. (4) Conclusions: AVF calcifications were a frequent finding in our analysis, but their presence does not seem to affect the 5-year AVF patency.

Reliable Stenosis Detection Based on Thrill Waveform Analysis Using Non-Contact Arteriovenous Fistula Imaging

Hemodialysis therapy is an extracorporeal circulation treatment that serves as a substitute for renal function. In Japan, patients receive this efficient four-hour treatment, three times per week, allowing them to maintain a social life nearly equivalent to that of healthy individuals. Before the treatment, two punctures are performed to establish extracorporeal circulation, and a high blood flow rate is essential to ensure efficient therapy. Specialized blood vessels created through arteriovenous fistula (AVF) surgery are utilized to achieve high blood flow rates. Although the AVF allows safe and efficient dialysis treatment, AVF stenosis leads to a serious problem in dialysis. To early detect this abnormal blood flow, auscultation and palpation methods are widely used in hospitals. However, these methods can only provide qualitative judgment of the AVF condition, so the results cannot be shared among other doctors and staff. Additionally, since the conventional methods require contact with the skin, some issues require consideration regarding infection and low reproducibility. In our previous study, we proposed an alternative method for auscultation using non-contact optical imaging technology. This study aims to construct a reliable AVF stenosis detection method using Thrill waveform analysis based on the developed non-contact device to solve the problem with the contact palpation method. This paper demonstrates the performance validation of the non-contact imaging in the normal AVF group (206 total data, 75 patients, mean age: 69.1 years) and in the treatable stenosis group (107 total data, 17 patients, mean age: 70.1 years). The experimental results of the Mann-Whitney U test showed a significant difference (p=0.0002) between the normal and abnormal groups, which indicated the effectiveness of the proposed method as a new possible alternative to palpation.

Percutaneous Endovascular Creation of a Neo-arteriovenous Fistula in Dysfunctional Hemodialysis Fistulas

PURPOSE

Arteriovenous fistulas (AVF) is the preferred type of hemodialysis access, but when an arteriovenous anastomosis (AVA) calcifies, surgical revision of the AVF may be required. We report a technique to create percutaneous artery-to-vein intervascular neo-fistulas for re-anastomosis of AVA and evaluate its safety and efficacy.

MATERIALS AND METHODS

9 patients who failed either guidewire navigation or conventional balloon dilation for calcified AVA stenosis/occlusion underwent a salvage procedure of their dialysis shunt by the percutaneous creation of a new arteriovenous fistula. Needle puncture of the adjacent supplying artery and outflow vein under ultrasonographic and/or fluoroscopic guidance was performed and followed by balloon dilation, with or without stent graft placement. The detailed techniques, technical success, primary neo-fistula patency, primary and secondary access patency rates were reported herein.

RESULTS

Technical success was achieved in 100% of the 9 patients treated (7 neo-fistulas with stents and 2 neo-fistulas without stent placement). The median primary neo-fistula and access patencies were 15 and 5 months, respectively. The primary neo-fistula patency rates at 6, 12, and 18 months were 72.9%, 54.7% and 27.9%, respectively, with secondary neo-fistula and access patency rates of 72.9%, 72.9% and 72.9%, respectively. One delayed complication of pseudoaneurysm formation occurred, which was managed by the successful endovascular deployment of a stent graft on an out-patient basis.

CONCLUSION

Percutaneous artery-to-vein intervascular neo-fistula creation is feasible for re-anastomosing calcified AVA, with low adverse effects and acceptable primary neo-fistula and secondary access patency.

Health-care Professionals' Perspectives on Ultrasound Evaluation of Arteriovenous Hemodialysis Fistula: A Narrative Review

Arteriovenous hemodialysis fistulas play a critical role in maintaining life on hemodialysis. With the growing use of Doppler ultrasound in nephrology, its utility has expanded to improve the prognosis and quality of life of patients receiving hemodialysis. On a fistula care team, different health-care professionals, including nephrologists, dialysis technicians, and surgeons or vascular interventionalists, require different information. This review article comprehensively explains how Doppler ultrasound evaluation can be beneficial in the management of arteriovenous fistulas from different perspectives of health-care professionals. The article also introduces the pathophysiology of arteriovenous fistula disease and provides a thorough introduction to the use of Doppler ultrasound for the evaluation of arteriovenous fistulas and their associated diseases, addressing the need for a comprehensive understanding among ultrasound practitioners.

Retrospective analysis of predictive factors for AVF dysfunction in patients undergoing MHD

To construct an early clinical prediction model for AVF dysfunction in patients undergoing Maintenance Hemodialysis (MHD) and perform internal and external verifications. We retrospectively examined clinical data from 150 patients diagnosed with MHD at Hefei Third People's Hospital from January 2014 to June 2023. Depending on arteriovenous fistula (AVF) functionality, patients were categorized into dysfunctional (n = 62) and functional (n = 88) cohorts. Using the least absolute shrinkage and selection operator(LASSO) regression model, variables potentially influencing AVF functionality were filtered using selected variables that underwent multifactorial logistic regression analysis. The Nomogram model was constructed using the R software, and the Area Under Curve(AUC) value was calculated. The model's accuracy was appraised through the calibration curve and Hosmer-Lemeshow test, with the model undergoing internal validation using the bootstrap method. There were 11 factors exhibiting differences between the group of patients with AVF dysfunction and the group with normal AVF function, including age, sex, course of renal failure, diabetes, hyperlipidemia, Platelet count (PLT), Calcium (Ca), Phosphorus, D-dimer (D-D), Fibrinogen (Fib), and Anastomotic width. These identified factors are included as candidate predictive variables in the LASSO regression analysis. LASSO regression identified age, sex, diabetes, hyperlipidemia, anastomotic diameter, blood phosphorus, and serum D-D levels as 7 predictive factors. Unconditional binary logistic regression analysis revealed that advanced age (OR = 4.358, 95% CI: 1.454-13.062), diabetes (OR = 4.158, 95% CI: 1.243-13.907), hyperlipidemia (OR = 3.651, 95% CI: 1.066-12.499), D-D (OR = 1.311, 95% CI: 1.063-1.616), and hyperphosphatemia (OR = 4.986, 95% CI: 2.513-9.892) emerged as independent risk factors for AVF dysfunction in MHD patients. The AUC of the predictive model was 0.934 (95% CI: 0.897-0.971). The Hosmer-Lemeshow test showed high consistency between the model's predictive results and actual clinical observations (χ2 = 1.553, P = .092). Internal validation revealed an AUC of 0.911 (95% CI: 0.866-0.956), with the Calibration calibration curve nearing the ideal curve. Advanced age, coexisting diabetes, hyperlipidemia, blood D-D levels, and hyperphosphatemia are independent risk factors for AVF dysfunction in patients undergoing MHD.

CEUS-guided PTA on stenotic AVF: Morphological and functional point of view

BACKGROUND

Stenosis represents the main cause of hemodialysis fistula malfunction. The ultrasound-guided angioplasty with ecographic contrast (CEUS) could provide further advantages to the classical ultrasound guided method improving the morphological characterization of the stenosis and providing quantitative data with the creation of time intensity curves (TIC) collecting functional data comparable between pre and post procedure.

METHODS

A total of 10 CEUS-guided angioplasties were performed on malfunctioning fistulas. The sonographic contrast medium was injected into the vascular tree trough the introducer. Morphological and functional data nature were collected. Were generated TIC curves, obtained by positioning a ROI in correspondence with the post-stenotic tract of the efferent vein. The data collected, regarding the peak intensity reached by the signal (PI) and the time to reach the peak signal intensity (TTP), were compared in the pre and post-procedural phase with flow of vascular access (Qa) and resistance indices (RI).

RESULTS

Statistically significant correlation (p < 0.05) was observed between Qa and TTP (r = 0.77; p = 0.009), RI and TTP (r = 0.71; p = 0.02), Qa and PI (r = 0.86; p = 0.0012), and between RI and PI (r = 0.88; p < 0.001).

CONCLUSION

In addition to the advantages associated with the use of ultrasound contrast medium in improving the visualization and characterization of the stenosis by facilitating the PTA procedure, the functional data deriving from the quantitative analysis provide new parameters for evaluating the success of the procedure which could also be used as predictive markers of stenosis recurrence together with the classical ones.

Hemodialysis Access: US for Preprocedural Mapping and Evaluation of Maturity and Access Dysfunction

Patients with kidney failure require kidney replacement therapy. While renal transplantation remains the treatment of choice for kidney failure, renal replacement therapy with hemodialysis may be required owing to the limited availability and length of time patients may wait for allografts or for patients ineligible for transplant owing to advanced age or comorbidities. The ideal hemodialysis access should provide complication-free dialysis by creating a direct connection between an artery and vein with adequate blood flow that can be reliably and easily accessed percutaneously several times a week. Surgical arteriovenous fistulas and grafts are commonly created for hemodialysis access, with newer techniques that involve the use of minimally invasive endovascular approaches. The emphasis on proactive planning for the placement, protection, and preservation of the next vascular access before the current one fails has increased the use of US for preoperative mapping and monitoring of complications for potential interventions. Preoperative US of the extremity vasculature helps assess anatomic suitability before vascular access creation, increasing the rates of successful maturation. A US mapping protocol ensures reliable measurements and clear communication of anatomic variants that may alter surgical planning. Postoperative imaging helps assess fistula maturation before cannulation for dialysis and evaluates for early and late complications associated with arteriovenous access. Clinical and US findings can suggest developing stenosis that may progress to thrombosis and loss of access function, which can be treated with percutaneous vascular interventions to preserve access patency. Vascular access steal, aneurysms and pseudoaneurysms, and fluid collections are other complications amenable to US evaluation. ©RSNA, 2023 Supplemental material is available for this article. Test Your Knowledge questions for this article are available through the Online Learning Center.

Successful treatment of a brachial artery pseudoaneurysm in a brachiobasilic arteriovenous fistula using ultrasound-guided manual compression

Pseudoaneurysm is a well-recognized complication seen in arteriovenous fistula (AVF) which usually involves the venous segments. Ultrasound-guided manual compression (UGMC) is a non-invasive and effective treatment for the management of pseudoaneurysms involving the venous segment. Pseudoaneurysm of the arterial segment of AVF is rare complication which usually needs surgical intervention. We report the first successful treatment case of a brachial artery pseudoaneurysm in a brachiobasilic arteriovenous fistula using ultrasound-guided manual compression. The patient presented with a 30 × 30 mm pulsatile swelling below the cubital fossa after second session of hemodialysis using an AVF created 8 weeks earlier. Ultrasound doppler demonstrated a brachial artery pseudoaneurysm in the non-transposed brachiobasilic fistula. Complete occlusion of the cavity with thrombus formation was accomplished after 55 min of compression and the psuedoaneurysm did not recur. UGMC can be an alternative treatment option for select cases of arterial segment pseudoaneurysm in AVF.

Multiparametric ultrasound for upper extremity dialysis access evaluation

The evolution of ultrasound (US) techniques has greatly improved the evaluation of many parameters in dialysis vascular access, which is typically achieved through an arteriovenous fistula (AVF) or graft (AVG). These techniques include grayscale B-mode, color Doppler, power Doppler, spectral Doppler, non-Doppler US flow imaging techniques, contrast-enhanced US, and elastography. In conjunction with a patient's medical history and physical examination, US provides crucial information about the native vascular bed prior to the surgical creation of an arteriovenous anastomosis. It also tracks the maturation progress of the newly created AVF or AVG and aids in diagnosing potential complications of the vascular access. These complications include thrombosis, steal syndrome, aneurysms, pseudoaneurysms, hematomas, infection, ischemic neuropathy, exacerbation of preexisting congestive heart failure, and stenosis.

Ultrasonography-Guided Procedures in the Intensive Care Setting

Ultrasonography guidance can help make procedures safer and more effective, particularly in the intensive care setting. This article discusses techniques to optimize periprocedural ultrasonography and reviews common intensive care procedures for which ultrasonography can be used: vascular access procedures, paracentesis, thoracentesis, and pericardiocentesis.

Deep learning analysis of blood flow sounds to detect arteriovenous fistula stenosis

For hemodialysis patients, arteriovenous fistula (AVF) patency determines whether adequate hemofiltration can be achieved, and directly influences clinical outcomes. Here, we report the development and performance of a deep learning model for automated AVF stenosis screening based on the sound of AVF blood flow using supervised learning with data validated by ultrasound. We demonstrate the importance of contextualizing the sound with location metadata as the characteristics of the blood flow sound varies significantly along the AVF. We found the best model to be a vision transformer trained on spectrogram images. Our model can screen for stenosis at a performance level comparable to that of a nephrologist performing a physical exam, but with the advantage of being automated and scalable. In a high-volume, resource-limited clinical setting, automated AVF stenosis screening can help ensure patient safety via early detection of at-risk vascular access, streamline the dialysis workflow, and serve as a patient-facing tool to allow for at-home, self-screening.

Maintenance and Salvage of Hemodialysis Access

Many end-stage kidney failure patients require hemodialysis as a life-sustaining treatment. Hemodialysis access via arteriovenous fistula or graft creation is preferred over long-term dialysis catheters, but intervention to maintain patency and prevent access failure is common. Endovascular and open surgical techniques are both utilized to address the underlying etiology of failure. Endovascular options include balloon angioplasty, angioplasty with stenting, and drug-eluting stents. Open revision is commonly needed for recurrent stenosis, aneurysmal or pseudoaneurysmal change, hemodialysis access-induced distal ischemia, and infection. Treatment plans should be guided by patient's individualized goals of care and require a multidisciplinary approach to the management of this complex disease.

Surgical Management, Prevention and Outcomes for Aneurysms of Arteriovenous Dialysis Fistulas: A Case Series Study and Review

The escalating population of individuals afflicted with end-stage renal disease necessitates the provision of secure and efficacious vascular access for hemodialysis, with arteriovenous fistulas representing a preferred option. Nonetheless, the creation of dialysis fistulas may entail complications, including the occurrence of fistula aneurysms that may require surgical intervention. This study included eight patients with large aneurysms of dialysis fistulas and aimed to evaluate the safety and effectiveness of classic, endovascular, or hybrid methods for fistula reconstruction or ligation, depending on the indications. Vascular interventions were performed on patients on chronic hemodialysis and on those in whom hemodialysis was discontinued due to the proper functioning of the transplanted kidney. Performed procedures were considered safe and effective. The reconstructed fistulas provided the patients with patent vascular access, allowing for continued hemodialysis. No re-aneurysmal dilatation of the reconstructed or ligated fistulas was observed. Regular monitoring of dialysis fistulas is crucial to detect complications in time. Guidelines should be established to specify the dimensions at which fistula aneurysm should be excised and whether to remove asymptomatic aneurysms at all. For patients who have undergone kidney transplantation, outlines should indicate when the fistula should be preserved and when it should be ligated.

Imaging Patients with Kidney Failure

The approach to imaging a patient with kidney failure continues to evolve. Overstatement of the risk of iodinated contrast material-induced (ie, contrast-induced) acute kidney injury and new guidelines for administration of gadolinium-based contrast media affect screening and the choice of contrast material. Treatment of kidney failure requires dialysis or a kidney transplant. Pretransplant imaging includes assessment for the feasibility of performing a transplant and evaluation for underlying malignancy and peripheral vascular disease. Patients with kidney failure are at high risk for renal cell carcinoma. Subtypes that occur exclusively or more commonly in patients with kidney failure, such as acquired cystic kidney disease, renal cell carcinoma, and clear cell papillary renal cell carcinoma, have specific clinical-pathologic characteristics, with indolent behavior. Performing US for dialysis planning increases the success of placement of an arteriovenous fistula, while postoperative US evaluation is essential in assessment of access dysfunction. Systemic manifestations in patients with kidney failure are multifactorial and may relate to the underlying cause of renal failure or may be secondary to treatment effects. Disturbances in mineral and bone metabolism and soft-tissue and vascular calcifications are seen in patients with chronic kidney disease and mineral bone disorder. Neurologic and cardiothoracic complications are also common. The authors provide a comprehensive overview of imaging considerations for patients with kidney failure, including the appropriate use of CT, MRI, and US with their respective contrast agents; the use of imaging in transplant workup and dialysis assessment; and the common renal and extrarenal manifestations of kidney failure. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Open resection for a large iatrogenic radial artery pseudoaneurysm. Case report

INTRODUCTION AND IMPORTANCE

We present the case in which a large symptomatic pseudoaneurysm (PSA), 6 × 5 cm, with one year of evolution on the path of the right radial artery (RRA) appeared after its punction and cannulation for performing cardiac catheterism in an atrial fibrillation (AF) indefinite anticoagulated patient. Diagnosis and surgical planning were consolidated only by using color duplex ultrasound (CDU), contrasted images were not indicated. The open surgical management was performed during a short-time supraclavicular blockade of peripheral nerves without stopping nor bridging anticoagulant therapy. Complete excision of the deforming mass with no blood loss, decompression of the adjacent structures and direct closure of the arterial defect without compromising of its lumen and path were also achieved.

CASE PRESENTATION

A 74-year-old, Hispanic male patient and former smoker underwent coronary catheterization for thoracic typical pain. One year after, he is admitted for move restrictive pain in distal right forearm and hand paresthesia related to a rapidly growing right radial artery PSA of 6 cm in diameter where the indefinite anticoagulation, indicated for chronic AF, confers a risk of major bleeding. After clinic and exclusive CDU assessing, the patient granted us written authorization for performing an open surgery. One year follow up showed an asymptomatic patient with no RRA residual lesions.

CLINICAL DISCUSSION

Although contrasted are the preferred diagnosis methods when arterial issues are suspected especially angiography since, when indicated, the endovascular treatment may be performed immediately after diagnosis. The CDU performed with a high-sensitivity transducer is the image of choice for an immediate differential diagnosis (Meola et al., 2021 [1]). In addition, it allowed us to see both, the particular PSA inside structure and the patency of ipsilateral ulnar artery, necessary details to propose the successful open surgical treatment finally conducted.

CONCLUSION

Vascular and trauma surgeons should be trained to ensure the correct diagnosis based on preexisting medical conditions, clinical findings and those provided by CDU in order to offer an appropriate and definitive management to peripheral vascular iatrogenic lesions with potential bleeding risk, especially in anticoagulated patients. Since large limb deforming PSAs are recommended to be excided through open access, they should also be trained to perform it without additional risks nor sequelae. Since the number of AF patients is increasing worldwide, main aspects on anticoagulation therapy have to be taught to every surgical team.