Hemodialysis access ultrasound

Color Doppler ultrasound evaluation of arteriovenous grafts for hemodialysis

Although arteriovenous fistula (AVF) continues to be the vascular access of choice for the hemodialysis, arteriovenous graft (AVG) can be the best choice in certain categories of patients and could have several advantages over AVF in a "patient centered approach" to vascular access. In the clinical management of prosthetic fistulas, color Doppler ultrasound (CDU) is the imaging method of choice for identifying stenosis and other AVG complications. In this review, besides highlighting the pivotal role of CDU in the diagnosis of AVG complications, we will underline the key role that ultrasound can play in identifying those stenosis most likely to cause AVG thrombosis. Furthermore, we will emphasize the support that CDU can play in distinguishing the different types of grafts and prosthetic devices such as stent-grafts, in identifying AVG with lower survival, CDU utilities and limitations in the evaluation of freshly-implanted grafts, the different sites available for AVG volume flow measurement and their use based on the configuration of the prosthesis, the time interval elapsed from the surgical intervention and the integrity of the prosthetic walls.

Procedural comparison of a standard PTA balloon for fistula and graft maintenance procedures with the novel Chameleon™ PTA balloon catheter

Introduction:

The incidence of cephalic arch (CA) and central venous (CV) stenosis has been reported in the range of 30% in the literature. The purpose of this study is to compare contrast use, fluoroscopy time, and procedure time between standard imaging by injection of contrast through the access sheath versus injection of contrast through a novel PTA balloon with an integrated injection port.

Methods:

A multi-centered, retrospective evaluation of consecutive patients treated for CA and CV stenosis was performed. Data captured included demographics, co-morbidities, lesion characteristics/location, procedural details, volume of contrast used, fluoroscopy time, and procedure time. The control group was imaged and treated using standard practice with pre and post imaging performed through the sheath and intervention using standard PTA balloon. Imaging and treatment were performed using the Chameleon™ PTA catheter in the treatment arm.

Results:

A total of 68 consecutive patients were included. There were 34 patients in Group A and 34 patients in Group B. Average age was 65.2 versus 66.5 ( p = 0.284), respectively. There were no significant gender differences between groups. Prevalence of co-morbidities of hypertension, coronary artery disease, and diabetes was similar to national rates in both groups. Contrast volume, fluoroscopy time, and procedure time in Group B were significantly less when compared by multiple regression to Group A, correcting for potential confounders ( p = 0.0001, 0.0180, and 0.0008, respectively).

Conclusion:

Use of a PTA balloon with an integrated injection port shows potential for significant reduction in contrast dose, fluoroscopy time, and procedure time.

Clinical Aspects of Dialysis Interventions: Physical and Sonographic Findings

Physical examination (PE) of arteriovenous access remains of high clinical value and continues to be recommended by leading societies and guidelines. PE is easy to learn and perform. Once learned, examiners can provide a comprehensive arteriovenous (AV) access examination in 20 to 30 seconds. Therefore, we continue to advocate that AV access PE should be part of the training for all dialysis care providers. Similarly, ultrasound can provide important AV access evaluation and provide key information. It is relatively cheap and can be readily available at the bed side. Additionally, it is well accepted by patients, as it is not expected to be associated with pain or discomfort during the examination. We present in this review the key components of PE, signs and symptoms of AV access dysfunction, and the role of ultrasound in AV access evaluation as a complementary tool to PE.

The clinical importance of color Doppler ultrasonography in puncture related complications of hemodialysis vascular access

Background

The long-term survival of patients on hemodialysis (HD) is dependent on adequate HD which depends on quality and degree of functionality of vascular access. The aim of our study is to detect the role of color Doppler ultrasonography in evaluation of arteriovenous fistula (AVF).

Materials and methods

Between January 2017 and October 2017, 60 patients had complicated AVF at Qena General Hospital & Qena University Hospital as primary and tertiary centers respectively with the same age group between 18 and 50 years old, had no diabetes mellitus were evaluated using color duplex-Doppler ultrasound (CDUS) after AVF maturation for detection of complications and comparison between primary and tertiary centers of its incidence.

Results

The overall results revealed that 11 patients from 30 patients that had been referred to tertiary centers have complicated AVF (36.7%), and 19 patients had no shunt complication (63.3%). Twenty-two patients from 30 patients that had been referred to primary HD centers had complicated shunts. Thrombosis at tertiary centers represents 13.3%, stenosis 3.3% (1 patient), aneurysmal formation had 6.6% for (2 patients), hematoma 6.6%(2 patients), infection 3.3% (1 patient), venous hypertension 3.3% (1 patient), thrombosis and hematoma at primary centers 16.6% (5 patients for each), aneurysmal formation and infection 13.3% for each, and stenosis 10%.

Conclusions

CDUS is a readily-available, non-invasive, risk-free, bed-side technique that allows precise anatomic knowledge, qualitative, and quantitative data of the upper limb vascular system which greatly help in preoperative planning of AVF creation, assessment of prime time for puncture (maturation), early detection of complications, and choice of appropriate therapeutic procedure for their treatment.

Ultrasound in dialysis access: Opportunities and challenges

Sonography is increasingly being used by nephrologists and the field of dialysis access is no exception. Advances in technology have allowed the addition of this universally available, portable, non-invasive tool to the nephrologist's armamentarium, which provides information on both morphology and physiology without the need for contrast or radiation. Ultrasound may be used across the spectrum of dialysis access, including central venous catheter placements, vascular mapping, regional anesthesia, creation, maintenance and assessment of hemodialysis access as well as assessment of the abdominal wall and peritoneal dialysis catheter placements. However, the lack of exposure in most training programs limits incorporation of routine use of ultrasounds in nephrology practice. As our specialty embarks on the ultrasound revolution, a two-pronged approach is essential to provide ample training opportunities while ensuring establishment of basic standards for training and competency.

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.

Restoration of Autologous Arteriovenous Fistula by Removal of the Occluded Short Venous Part and Venovenous End-To-End Anastomosis in a Hemodialysis Patient

Standard salvage procedures for occuluded autologous arteriovenous fistula (AVF) in a hemodialysis patient are endovascular and/or surgical therapy. When endovascular therapy and thrombectomy prove unsuccessful, it is most likely that creating a new AVF or arteriovenous graft will be considered. However, if the occuluded venous part is short, we have adopted an operative technique for repair of AVF by removal of the occluded short venous part and venovenous end-to-end anastomosis. To our knowledge, the efficacy and clinical course of restoration of AVF by the technique have not been reported to date. Here, we describe the technique and report the successful treatment of a hemodialysis patient who developed AVF occlusion.

The role of mineral metabolism and inflammation on dialysis vascular access failure

Thrombosis of arteriovenous fistula (AVF) is the leading cause of vascular access (VA) loss usually due to silent stenosis. Therefore, assessment of relevant risk factors of VA monitoring may provide insight into potential therapeutic targets for stenosis and thrombosis. The aim of this study was to evaluate the influence of cardiovascular risk factors (including inflammation and mineral metabolism dysfunctions) on the failure of internal AVF in HD patients.

128 HD patients with internal AVF were included in the study and followed up for two years. At baseline, VA morphology and function were followed by Doppler ultrasonography and serum albumin, prealbumine, C-reactive protein, orosomucoid, calcium, phosphorus, parathyroid hormone, bone-type alkaline phosphatase, osteoprotegerin and receptor activator of nuclear factor κB ligand were measured.

At baseline, 50 stenoses were detected but none of them required any intervention. Age and biological parameters did not significantly differ between patients with or without VA stenosis. Over the two year- follow up, VA thrombosis occurred in 19 patients. Preexisting stenosis of VA was present in 9/19 patients (47.3% of cases) (chi-square = 3.708, p = 0.0538). Despite the low rate of events, phosphorus [1.75 (0.95–2.77) vs 1.42 (0.47–3.22) mmol/L, p = 0.0416], Calcium x Phosphorus product [4.00 (2.00–5.90) vs 3.40 (1.10–6.80) mmol2/L2, p = 0.0676] and parathyroid hormone [165.00 (1.00–944.00) vs 79.50 (1.00–846.60) ng/L, p = 0.0814) levels were higher in the 19 thrombotic patients whereas all other biological parameters did not significantly differ.

These results, which confirm that VA thrombosis occurs more frequently upon preexisting stenosis, also demonstrate that mineral metabolism disorders, compared to inflammation, may contribute to VA dysfunction leading to thrombosis.

Sonography of Arteriovenous Fistulas and Grafts

Arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) are the vascular accesses of choice for long-term hemodialysis. Strategies to establish and maintain functioning AVFs and AVGs are essential. In addition to clinical evaluation, ultrasound plays a critical role in the evaluation and maintenance of AVFs and AVGs. AVFs have a high rate of failure to mature which can be reliably diagnosed with ultrasound. Treatable etiologies of the failure to mature can often be diagnosed with ultrasound. Causes of secondary AVG failure can also be diagnosed with ultrasound and treated. AVGs have a relatively short functional life expectancy due to a high rate of AVG thrombosis. Ultrasound is a safe, noninvasive way to diagnose vascular stenosis in both AVFs and AVGs prior to thrombosis, potentially saving the access. Routine surveillance ultrasound of asymptomatic AVFs and AVGs is controversial with conflicting studies on its benefit. Routine surveillance ultrasound of AVFs and AVGs is not common practice.

Approach to the Swollen Arm With Chronic Dialysis Access: It's Not Just Deep Vein Thrombosis

The purposes of this pictorial essay are as follows: (1) Review a systematic approach to using sonography in the initial evaluation of patients with acute arm swelling and permanent dialysis access. (2) Identify normal grayscale and Doppler findings in arteriovenous fistulas and grafts. (3) Discuss a spectrum of vascular differential diagnoses for arm swelling in this setting, including stenosis of the access, draining vein complications, thrombosis, steal syndrome, and aneurysms, as well as several nonvascular causes. (4) Recognize findings that warrant further imaging evaluation or intervention.

MDCT angiography with 3D image reconstructions in the evaluation of failing arteriovenous fistulas and grafts in hemodialysis patients

BACKGROUND

Arteriovenous fistulas and grafts are the methods of choice for vascular access in renal failure patients in need of hemodialysis. Their major complication, however, is stenosis, which might lead to thrombosis.

PURPOSE

To demonstrate the usefulness of 16-MDCTA with 3D image reconstructions, in long-term hemodialysis patients with dysfunctional arteriovenous fistulas and grafts (AVF and AVG).

MATERIAL AND METHODS

During a 17-month period, 31 patients with dysfunctional AVF and AVG (24 AVF and seven AVG) were examined with MDCTA with 3D image postprocessing. Parameters such as comprehension of the anatomy, quality of contrast enhancement, and pathological vascular changes were measured. DSA was then performed in 24 patients.

RESULTS

MDCTA illustrated the anatomy of the AVF/AVG and the entire vascular tree to the heart, in a detailed and comprehensive manner in 93.5% of the evaluated segments, and depicted pathology of AVF/AVG or pathology of the associated vasculature. MDCTA demonstrated a total of 38 significant stenoses in 25 patients. DSA verified 37 stenoses in 24 patients and demonstrated two additional stenoses. MDCTA had thus a sensitivity of 95%. All 24 patients were treated with percutaneous transluminal angioplasty (PTA) with good technical results.

CONCLUSION

MDCTA with 3D reconstructions of dysfunctioning AVFs and AVGs in hemodialysis patients is an accurate and reliable diagnostic method helping customize future intervention.

Upper extremity venous Doppler ultrasound

Ultrasound is the initial imaging modality of choice when evaluating the upper extremity venous system. When sonographic findings are equivocal or nondiagnostic, particularly in evaluating the central deep veins, MR venography or catheter venography correlation may be helpful. Ultrasound provides an accurate, rapid, low-cost, portable, noninvasive method for screening, mapping, and surveillance of the upper extremity venous system.

Clinically immature arteriovenous hemodialysis fistulas: effect of US on salvage

PURPOSE

To retrospectively determine whether postoperative ultrasonography (US) of clinically immature dialysis fistulas can be used to identify potential anatomic origins of immaturity and whether correction of immature fistulas promotes fistula maturation.

MATERIALS AND METHODS

Institutional review board approval was obtained for this retrospective study, with waiver of informed consent. Postoperative US was performed in 95 consecutive subjects (52 men, 43 women; mean age, 58 years) with clinically immature fistulas. Fistulas were deemed sonographically mature if they had a diameter of at least 4 mm, an access flow of at least 500 mL/min, and a depth of no more than 5 mm from the skin surface. Fistulas were deemed clinically mature if they could be used for dialysis for at least 1 month. The proportion of subjects in different US subgroups with fistulas that matured during follow-up was compared with chi2 analysis.

RESULTS

Sixty-seven clinically immature fistulas were deemed sonographically immature. One or more remediable anatomic problems were detected with US in 60 subjects with sonographically immature fistulas; these problems included focal stenosis in 23, accessory veins in 34, and excessively deep veins in 19. Multiple abnormalities were present in 13 subjects. Of 58 subjects with sonographically immature fistulas and known clinical outcomes, 32 underwent an intervention. In those subjects who did not undergo a salvage procedure, only eight fistulas were usable for dialysis. Among those who underwent a salvage procedure, 25 fistulas were subsequently usable for dialysis (P < .001).

CONCLUSION

Clinically immature fistulas frequently have one or more potentially remediable problems seen at postoperative US. Problem-specific salvage procedures increase the proportion of fistulas that are usable for dialysis.

Electron-beam CT as a diagnostic modality in pediatric nephrology and renal transplant surgery

Electron-beam computed tomography is an imaging technology with a variety of medical applications, primarily in cardiology due to its sub-second acquisition time enabling visualization of a beating heart. Recently, this technique has also been introduced into other fields because of lower radiation exposure compared to traditional computed tomography, as well as the strengths of post-procedural three-dimensional visualization. This report evaluates electron-beam computed tomography as a diagnostic modality in pediatric nephrology patients. Seven patients reflecting typical clinical scenarios in pediatric nephrology were reviewed with regard to the value of electron-beam computed tomography and its contribution to the diagnostic workup. Electron-beam computed tomography is noninvasive and allows three-dimensional post-processing, enabling highly accurate images while requiring less radiation and acquisition time. It is very useful for clinical questions that require a detailed description of vascular and renal anatomy.

Hemodialysis arteriovenous fistula maturity: US evaluation

PURPOSE

To compare various objective ultrasonographic (US) criteria for native arteriovenous fistula (AVF) maturation with subsequent fistula outcomes and clinical evaluation by experienced dialysis nurses.

MATERIALS AND METHODS

US fistula evaluation results were analyzed retrospectively in 69 patients within 4 months after AVF placement; adequacy for dialysis was known in 54. Measurements included minimum venous diameter and blood flow rate. Experienced dialysis nurses examined 30 fistulas clinically. Predictors of fistula adequacy were analyzed with univariate and multivariate logistic regression. Mean fistula diameters and blood flow rates were compared by using analysis of variance or unpaired Student t tests.

RESULTS

Fistula adequacy for dialysis doubled if the minimum venous diameter was 0.4 cm or greater (89% [24 of 27]) versus less than 0.4 cm (44% [12 of 27]; P <.001). Fistula adequacy for dialysis was nearly doubled if flow volume was 500 mL/min or greater (84% [26 of 31]) versus less than 500 mL/min (43% [nine of 21]; P =.002). Combining venous diameter and flow volume increased fistula adequacy predictive value: minimum venous diameter of 0.4 cm or greater and flow volume of 500 mL/min or greater (95% [19 of 20]) versus neither criterion met (33% [five of 15]; P =.002). Women were less likely to have an adequate fistula diameter of 0.4 cm or greater: 40% (12 of 30) of women versus 69% (27 of 39; P =.015) of men. No significant differences in blood flow or minimum venous diameter were found during 2-4 postoperative months. Experienced dialysis nurses' accuracy in predicting eventual fistula maturity was 80% (24 of 30).

CONCLUSION

US measurements of AVF at 2-4 months in patients undergoing hemodialysis are highly predictive of fistula maturation and adequacy for dialysis.