Preoperative mapping for haemodialysis access surgery with CO(2) venography of the upper limb

The outcomes of carbon dioxide digital subtraction angiography for percutaneous transluminal balloon angioplasty of access circuits and venous routes in hemodialysis patients

The outcomes of carbon dioxide digital subtraction angiography (CO2-DSA) for performing percutaneous transluminal balloon angioplasty (balloon PTA) in hemodialysis patients has not been fully clarified. The purpose was to compare the outcomes of balloon PTA of hemodialysis shunts in terms of vessel patency between patients treated using CO2-DSA and conventional digital subtraction angiography using iodine contrast medium (C-DSA).We retrospectively evaluated 76 patients (38 males and 38 females, mean age: 65.0 ± 14.0 years). They were under hemodialysis and treated with balloon PTA using CO2-DSA or C-DSA at our institution between 2009 and 2016. Mean duration of the follow-up period was 25.59 ± 21.45 months. We compared the patency rates obtained after CO2-DSA-based balloon PTA with those after C-DSA-based balloon PTA. Secondary patency, which was defined as the duration of patency after all further endovascular interventions until surgical repair, was considered as the endpoint in this study.Overall, 19 and 57 patients underwent CO2-DSA- and C-DSA-based balloon PTA, respectively. CO2-DSA- and C-DSA-based balloon PTA produced clinical success rates of 100% and 96.5%, respectively. Blood vessel injury occurred in one patient who underwent C-DSA-based balloon PTA. No major complications occurred in CO2 group. At 24 months, the post-PTA secondary patency rates of CO2-DSA- and C-DSA-based balloon PTA were 94.1% and 93.9%, respectively (P = .9594).CO2-DSA is safe for hemodialysis patients. Compared with C-DSA, CO2-DSA-based balloon PTA produces have a similar secondary patency rate.

Outcomes of Transposition of Brachiobasilic Arteriovenous Fistula in Two-Stage Technique: A Single-Centre Experience With Literature Review

Introduction 

Arteriovenous fistulae (AVF) are considered a better option for long-term dialysis access. The distal radiocephalic AVF is the most preferred followed by proximal radiocephalic, brachiocephalic and brachiobasilic AVFs (BBAVF) with basilic vein transposition. In case of failure of AVF at other anatomical locations, BBAVF may improve the outcomes for patients needing dialysis for long term. The two-stage technique of BBAVF has easier dissection and lesser devascularisation risk. The disadvantages are need for two interventions and delay in maturation.

Materials and Method

It was a retrospective observational study including 42 patients who underwent transposition of BBAVF as two-stage procedure from June 2014 to July 2018. The data recorded were demographic characteristics, such as median age, gender, dialysis status at AVF creation and operative duration. Complications like postoperative limb oedema, bleeding and thrombosis of AVF were recorded. Patency and access outcome of AVF were documented at three-month follow-up.

Results 

Among 42 patients, 27 (64.3%) were males. The median age was 50 years. Around 14% of patients had minor complications like oedema. Eight (19%) patients needed re-exploration due to bleeding or thrombosis. The early access failure rate that is a failure before discharge was 4.7%. The patency rate at three months was 90.5%, but the primary functional rate was 74%.

Conclusion 

Transposition of BBAVF as a two-step technique is associated with reasonable patency rate and primary functional rate. The related complications were low, and a good number of fistulae could be saved with timely intervention.

Use of carbon dioxide as an intravascular contrast agent: A review of current literature

Use of X-ray contrast allows us to differentiate between two or more adjacent structures on radiographic studies. The X-ray contrast agent can be the one with increase X-ray absorption, like iodine and a barium X-ray contrast agent or the one with decrease X-ray absorption like air and carbon dioxide contrast agent. Each contrast agent possesses different risks and benefits in various ways. Carbon dioxide as an intravascular contrast agent can be used as an alternative intravascular contrast agent and has superior results in some cases. In patients with renal dysfunction or iodinated contrast allergy, the use of Iodinated Contrast Agent poses the risk of considerable morbidity. Similarly, use of Gadolinium is discouraged in subject with severe renal dysfunction. Use of carbon dioxide (CO₂) as an intravascular contrast, offers an alternative in such patients for certain procedures, as it is not nephrotoxic and it does not incite allergic reactions. It is inexpensive, readily available and due to its unique physical properties, it can be used to image a wide variety of vascular beds and chambers. The aim of this paper is to systemically review the current literature to describe the indications, contraindications, adverse effects, instruments, precautions, latest methodologies and data supporting for the use of CO₂ as a contrast agent.

Imaging in Vascular Access

This review examines four imaging modalities; ultrasound (US), digital subtraction angiography (DSA), magnetic resonance imaging (MRI) and computed tomography (CT), that have common or potential applications in vascular access (VA). The four modalities are reviewed under their primary uses, techniques, advantages and disadvantages, and future directions that are specific to VA. Currently, US is the most commonly used modality in VA because it is cheaper (relative to other modalities), accessible, non-ionising, and does not require the use of contrast agents. DSA is predominantly only performed when an intervention is indicated. MRI is limited by its cost and the time required for image acquisition that mainly confines it to the realm of research where high resolution is required. CT’s short acquisition times and high resolution make it useful as a problem-solving tool in complex cases, although accessibility can be an issue. All four imaging modalities have advantages and disadvantages that limit their use in this particular patient cohort. Current imaging in VA comprises an integrated approach with each modality providing particular uses dependent on their capabilities. MRI and CT, which currently have limited use, may have increasingly important future roles in complex cases where detailed analysis is required.

Arteriovenous fistula in dialysis patients: Factors implicated in early and late AVF maturation failure

Increasing numbers of patients are being diagnosed with end-stage renal disease (ESRD), and the demand for on haemodialysis (HD) is rising. Arteriovenous fistulae (AVFs) remain the best conduit for adequate HD, with fewer complications associated with long-term use compared to bypass grafts and central venous catheters. However, it is known that many newly formed fistulae do not mature to provide useful HD access. The paper provides a narrative overview of factors influencing the process of AVF maturation failure.

Current tools for prediction of arteriovenous fistula outcomes

It remains challenging to accurately predict whether an individual arteriovenous fistula (AVF) will mature and be useable for haemodialysis vascular access. Current best practice involves the use of routine clinical assessment and ultrasonography complemented by selective venography and magnetic resonance imaging. The purpose of this literature review is to describe current practices in relation to pre-operative assessment prior to AVF formation and highlight potential areas for future research to improve the clinical prediction of AVF outcomes.

One-stage vs. two-stage brachio-basilic arteriovenous fistula for dialysis access: a systematic review and a meta-analysis

Introduction

A brachiobasilic arteriovenous fistula (BB-AVF) can provide access for haemodialysis in patients who are not eligible for a more superficial fistula. However, it is unclear whether one- or two-stage BB-AVF is the best option for patients.

Aim

To systematically assess the difference between both procedures in terms of access maturation, patency and postoperative complications.

Methods

Online search for randomised controlled trials (RCTs) and observational studies that compared the one-stage versus the two-stage technique for creating a BB-AVF.

Results

Eight studies were included (849 patients with 859 fistulas), 366 created using a one-stage technique, while 493 in a two-stage approach. There was no statistically significant difference between the two groups in the rate of successful maturation (Pooled risk ratio = 0.95 [0.82, 1.11], P = 0.53). Similarly, the incidence of postoperative haematoma (Pooled risk ratio = 0.73 [0.34, 1.58], P = 0.43), wound infection (Pooled risk ratio = 0.77 [0.35, 1.68], P = 0.51) and steal syndrome (Pooled risk ratio = 0.65 [0.27, 1.53], P = 0.32) were statistically comparable.

Conclusion

Although more studies seem to favour the two-stage BVT approach, evidence in the literature is not sufficient to draw a final conclusion as the difference between the one-stage and the two-stage approaches for creation of a BB-AVF is not statistically significant in terms of the overall maturation rate and postoperative complications. Patency rates (primary, assisted primary and secondary) were comparable in the majority of studies. Large randomised properly conducted trials with superior methodology and adequate sub-group analysis are needed before making a final recommendation.