Improving haemodialysis fistula maturation following early ultrasound vascular mapping: 'The Venous Preservation Scan'.

AIM: Formation of autogenous arteriovenous fistula (AVF) in patients with chronic kidney disease (CKD) is complicated by a high primary failure rate. We hypothesized that early (months to years before AVF creation) Venous Preservation Scan (VPS) followed by vasculature preservation is effective in protecting the patient's best 'for fistula' vasculature. This study was performed to evaluate the impact of VPS on AVF outcomes. METHODS: The case records of 123 patients who underwent ultrasound mapping for AVF creation in a district hospital were reviewed. Ninety-seven were VPS and 26 were Routine Pre-Operative Planning Scan (RPOPS) performed immediately prior to surgery. Outcomes of 21 patients who went onto AVF creation in the VPS group were compared to 23 patients in the RPOPS group. RESULTS: Success and complication rates for AVF placement in patients who underwent VPS versus RPOPS were 100% versus 91.3% (P = 0.27) and 0 versus 8.7% (P = 0.23). A greater proportion of AVF created following RPOPS required intervention before maturation (47.6% vs 19%, P = 0.05). The median primary patency of AVF created following VPS versus RPOPS was 492 (IQR 222, 1219) versus 169 (IQR 116, 414) days (P = 0.02). The cumulative patency did not differ between the two groups (median = 807 (IQR 499, 1308) versus 1059 (IQR 331, 1263) days, P = 0.26). CONCLUSIONS: This small study suggests that VPS may favourably influence the survival of primary AVF and reduce the need for assisted interventions. However, confirmation with larger randomized controlled trial is warranted.

Pericatheter Leak Associated With Earlier Peritoneal Dialysis Initiation Does Not Influence Long-Term Outcomes.

Introduction: Internationally, peritoneal dialysis (PD) is increasingly being commenced within 2 weeks of catheter insertion. Studies are warranted to evaluate outcomes of this strategy. Methods: This study examines outcomes of early-start PD (ESPD) and conventional-start PD (CSPD), commencing at ≤14 days and >14 days after catheter insertion, respectively. All adults with kidney failure within a large metropolitan PD unit initiating PD through a new catheter, inserted using laparoscopic or modified Seldinger technique, between August 2019 and August 2022, were included in this retrospective observational study. Demographic data and episodes of infectious and mechanical complications were collected using electronic medical records. Analysis was conducted using analysis of variance and Chi-square testing. A P-value < 0.05 was significant with Bonferroni correction performed where relevant. Kaplan-Meier and competing risks analyses were performed for time to PD-related peritonitis and transfer to hemodialysis. Results: A total of 297 patients (70% male, mean age 58.7 years) were included, with 130 (43.8%) patients undertaking ESPD. Most patients had laparoscopically inserted catheters (65.3%) and 65 patients (22.0%) received prior hemodialysis. When compared to CSPD, ESPD was associated with a higher number of pericatheter leaks (6.9% vs. 0.6%, P = 0.003), with otherwise similar complication episodes and no significant difference with respect to time to PD-related peritonitis or transfer to hemodialysis. Catheter insertion technique or prior hemodialysis treatment did not significantly influence outcomes. Conclusion: ESPD is associated with increased pericatheter leaks when compared to CSPD, with an otherwise similar complication profile.

Changing the peritoneal dialysis access algorithm with a precise technique of percutaneous Seldinger PD catheter placement.

BACKGROUND: In 1953, Swedish radiologist Sven Seldinger introduced a technique for blood vessel or hollow organ access using a needle, guide wire and catheter. Over the last two decades, this technique has been used for Peritoneal Dialysis (PD) catheter placement, "Seldinger PD" (SPD). To improve the safety and accuracy of SPD, ultrasound, X-ray guidance, contrast imaging and micropuncture techniques have been incorporated to a greater or lesser extent. METHODS: This manuscript describes a new and rigorous technique of SPD developed at our unit and results in the first 64 cases. One of our goals was to replace emergency Central Vein Catheter Hemodialysis with "Urgent-Start" PD. We therefore sought to develop a procedure that was ultra-safe, minimally invasive and readily done on the sickest patients under Local Anesthetic. As the technique was new to our unit, and because of progressive modifications of the technique, some of the results reflect our "learning curve." In addition, 55% of the patients referred to our program had "crashed" into renal failure, 32% were deemed "unfit for General Anaesthesia" by the Anaesthetists and 53% were moderately to severely obese, resulting in a very morbid and vulnerable cohort. RESULTS: Despite this, we had no procedure related mortality, no organ injury and no significant bleeding. Technical success was 97% (intention-to-treat). Urgent Start PD was used in 36%; overall, 3/61 catheters placed experienced PD fluid leak. Correct catheter tip placement - in the Pelvic Pouch - was documented in all cases; significant catheter migration was seen in 18% of those with imaging follow-up, only two requiring revision. Most catheter migrations occurred early in our series before our low peritoneal puncture technique became standard. CONCLUSIONS: We believe this SPD technique is safe, precise, clinically and financially cost-effective and can replace other forms of PD placement in most situations.

Defining a significant stenosis in an autologous radio-cephalic arteriovenous fistula for hemodialysis.

The current definition of a significant stenosis in an autologous arteriovenous fistula (aAVF), the percentage narrowing compared with the adjacent "normal" vessel, is inaccurate. We believe a significant stenosis in the aAVF is an absolute minimal luminal diameter determined by the requirements of the hemodialysis pump. To determine what absolute diameter constitutes a hemodynamically significant stenosis in a radio-cephalic autologous arteriovenous fistula (RC aAVF), the minimal luminal diameter of dysfunctional RC aAVF was compared to that of functional RC aAVF using grayscale and color ultrasound. There were 93 fistulas in study group and 77 in control group. The mean minimum luminal diameter in study group was significantly lower than in control group (2.19 vs. 4.71 mm, p 0.001). With a cutoff value of 2.7 mm, there was 90% sensitivity and 80% specificity in distinguishing functional fistula from dysfunctional fistula. The area under the receiver-operator curve was 90% (CI 84-94%), indicating that a 2.7 mm diameter is accurate in discriminating functional from dysfunctional fistulas. An absolute minimal luminal diameter of 2.7 mm, as determined with grayscale and color ultrasound, is a useful cutoff for defining significant stenosis in a RC aAVF.

Vertical or transverse incisions for access to the femoral artery: a randomized control study.

BACKGROUND: To look at wound complications with either a transverse or vertical groin incision in vascular surgery. METHODS: All patients undergoing vascular procedure requiring access to femoral vessels were randomized to either a vertical or transverse incision. Patients were followed up for 28 days after the procedure and examined for wound infection, wound breakdown, development of lymphatic leak and lymphatic collection. RESULTS: 88 patients (116 groins) were randomised to either incision. Of these, 55 groins had transverse incisions and the remaining had vertical incisions. There was no significant difference in the patient's age, sex, smoking, diabetes, operative times and use of prosthetic material. 29/61 (47.5%) of vertical incisions and 7/55 (12.7%) of transverse incisions had wound complications (p<0.001). There were 13(11%) wound infections in the 116 groins by day 28. There were 3 wound infections in the transverse group and 10 infections in the vertical group (p=0.062). There were 17 (27.9%) lymphatic leaks in the vertical incisions compared to 7(12.7%) in the transverse incisions (p=0.044). The majority of infections were diagnosed after patient discharge from hospital. CONCLUSION: Wound complications are higher with vertical incision. Many infections are diagnosed after patient discharge. We recommend transverse incisions for access to the femoral vessels in the groin.

Colour duplex ultrasound accurately identifies focal stenoses in dysfunctional autogenous arteriovenous fistulae.

AIMS: The aims of this study is to correlate colour duplex ultrasonography (US) with contrast fistulography for the detection of functional stenoses in the autogenous AVF (arterio-venous fistula) circuit. METHODOLOGY: Colour duplex US scans of 93 dialysis patients with dysfunctional AVF were compared with fistulograms performed within 6 weeks of the US. The AVF circuit was divided into six zones: inflow artery; anastomosis; distal vein; mid vein; proximal vein; and central vein. Colour duplex US and fistulogram images/reports were independently re-reported for stenoses in each fistula zone by two trained clinicians blinded to the outcomes. For each fistula, only zones examined by both modalities were included in the study. Kappa analysis of the results was performed to assess the accuracy of colour duplex US in the dysfunctional AVF circuit. RESULTS: Most AVF studied were radio-cephalic (59%) or brachio-cephalic (22%). Stenoses identified within the AV circuit in order of frequency were: distal vein (41), mid vein (23), arterial (12), proximal vein (7) and anastomosis (3). The interval between US and fistulogram studies was 33 + or - 29 days. Congruence of results between US and fistulograms ranged from 85% to 96%, depending on the zone examined. Kappa analysis of this US versus fistulogram data was also moderate to good, ranging from 0.72 and 0.91. CONCLUSIONS: Colour duplex US provides an accurate diagnostic assessment of a dysfunctional autogneous AVF, and is an important planning tool for subsequent open or endovascular intervention. It is particularly accurate in the peri-anastomotic area of the fistula which harbours the majority of fistula problems.

Results of the endovascular treatment system for occluded native arteriovenous fistula.

BACKGROUND: Arteriovenous fistula is the definitive vascular access for patients on long-term haemodialysis. The aim of this study is to present the techniques and results of the Endovascular Treatment System that we have developed for managing the occluded native arteriovenous fistula. METHODS: The current study is a retrospective chart review on all patients who presented with an occluded native arteriovenous fistula and underwent attempted recanalization between 1 January 2005 and 31 December 2014. RESULTS: A total of 130 patients were included in the study. Post-intervention primary access patency was 83.8% at 6 months, 78.7% at 12 months, 64.6% at 2 years and 59.6% at 3 years. Post-intervention assisted access patency in fistulas-in-use was 86.5% at 6 months, 81% at 12 months, 66.8% at 2 years and 61.2% at 3 years. Post-intervention secondary patency for all cases was 84.7% at 6 months, 80.2% at 12 months, 66.1% at 2 years and 62% at 3 years. Post-intervention secondary patency in fistula-in-use was 91.1% at 6 months, 90% at 12 months, 85% at 2 years and 74.6% at 3 years. Access survival nor patency differed significantly when incisional thrombectomy was compared to angioplasty with or without stenting with access survival of 91.2% and 92.5% at 12 months and access patency of 82.9% and 89.7% at 12 months (P = 0.834 and P = 0.898, respectively). CONCLUSIONS: In autologous arteriovenous thrombosed fistulae, the use of endovascular techniques to revive the access is a viable and safe technique to employ in most cases.

Multicentre, randomised, blinded, control trial of drug-eluting balloon vs Sham in recurrent native dialysis fistula stenoses.

BACKGROUND: Endovascular treatment of autogenous arteriovenous haemodialysis fistula stenosis has high reintervention rates. We investigate the effect of drug-eluting balloons in the treatment of recurrent haemodialysis fistula stenosis. METHODS: This is a randomised, controlled, investigator-initiated and run, prospective, blinded, multicentre trial. Patients with recurrent autogenous arteriovenous haemodialysis fistula stenosis received standard endovascular treatment plus drug-eluting balloon or standard endovascular treatment plus uncoated balloon (Sham). Primary endpoint was late lumen loss in trial area on ultrasound at 6 weeks, 3, 6 and 12 months. Secondary endpoints were freedom from reintervention to the Index Trial Area and decline in fistula flow (Qa). Interim analysis was performed at 6 months (unblinded due to timeliness). RESULTS: Patients with 132 recurrent stenoses (48% in bare Nitinol stents) were randomised with 70 receiving drug-eluting balloon and 62 Sham. At 6 months, decline in late lumen loss was 0.23 ± 0.03 mm/month for Sham and 0.045 ± 0.03 mm/month for drug-eluting balloon arm, a significant difference (0.18 mm, p = 0.0002). At 12 months, this difference persisted at 0.12 mm (p = 0.0003). At 6 months, significant difference in late lumen loss for instent restenoses (p = 0.0004) was observed, with non-significant difference for unstented restenoses (p = 0.065). Mean time for freedom from reintervention was 10.14 months for Sham versus 42.39 months for drug-eluting balloon (p = 0.001). The same was shown for instent (p = 0.014) and unstented (p = 0.029) restenoses. Qa decline rate at 6 months was 36.89 mL/min/month (Sham) and 0.41 mL/min (drug-eluting balloon). The difference was significant (36.48 mL/min; p = 0.02) and persisted to 12 months (p = 0.44). CONCLUSION: Paclitaxel drug-eluting balloon significantly delays restenosis after angioplasty for recurrent autogenous arteriovenous haemodialysis fistula stenosis, persisting to 12 months. Drug-eluting balloon significantly increases freedom from reintervention at 12 months with these effects true in stented and unstented fistulas.

Diameter of inflow as a predictor of radiocephalic fistula flow.

INTRODUCTION:: The optimal method for vascular access surveillance is largely unknown. A previous case-control study suggested a simplified anatomical measure obtained by Doppler ultrasound-the narrowest segment of the circuit or "minimal luminal diameter" may identify patients with a dysfunctional radiocephalic arteriovenous fistula. The relationship between minimal luminal diameter and access flow (Qa) in the radiocephalic arteriovenous fistula has not previously been studied. METHODS:: Patients undergoing Doppler ultrasound of a radiocephalic arteriovenous fistula over an 8-month period were identified retrospectively. Minimal luminal diameter was identified and demographic and clinical data were collected. Qa was estimated by Doppler estimation of brachial artery flow. The relationship between minimal luminal diameter and Qa was examined by correlation and using different levels of minimal luminal diameter as a simplified measure to detect or exclude low Qa (<600 mL/min). RESULTS:: A total of 81 Doppler ultrasound scans were performed. In all, 26 scans demonstrated brachial artery flow <600 mL/min. Simple logistic regression indicated a weak statistical relationship between the minimal luminal diameter and Qa (R2 = 0.27, p < 0.01). Minimal luminal diameter performed poorly as a marker of low Qa with low specificity, however, showed high negative predictive value for ruling out low Qa at a minimal luminal diameter of 3.2 mm or higher (94%). Qa estimated by brachial artery flow correlated well with Qa estimated by indicator dilution (R2 = 0.83, p < 0.01) without significant mean difference or proportional bias. CONCLUSION:: Minimal luminal diameter correlates weakly with Qa. Low minimal luminal diameter values should not be used in isolation to determine low Qa for a radiocephalic arteriovenous fistula. Conversely, minimal luminal diameter >3.2 mm largely excludes a low-flow radiocephalic arteriovenous fistula in this cohort. Brachial artery flow is a reasonable measure of Qa in comparison with indicator dilution.

Paclitaxel drug-eluting balloons to recurrent in-stent stenoses in autogenous dialysis fistulas: a retrospective study.

PURPOSE: To assess the effect of the Medtronic paclitaxel drug-eluting balloon (DEB) on re-intervention to in-stent stenoses in autogenous dialysis arteriovenous fistulas (AVFs). BACKGROUND: AVF is the optimum haemodialysis access. The commonest problem is stenosis, preventing maturation, causing inadequate dialysis or precipitating occlusion. Conventional angioplasty has a high recurrence rate. Successful drug elution in the coronary circulation led us to use DEBs in recurrent AVF stenoses since 2010. METHODS: This is a retrospective study, based on prospective audit data, using DEBs on recurrent in-stent stenotic lesions in the AVF circuit of our haemodialysis population. To analyse the effect of DEBs on re-intervention, we created two Kaplan-Meier curves. The first curve compares the last "disease-free-interval" pre-DEB intervention to the first "disease-free interval" post-DEB, giving us "re-intervention-free percentage at 12 months" pre- and post-DEB. The second curve takes into account the multiple pre- and post-DEB interventions to the index lesion, and uses a marginal proportional hazards model to estimate the hazard ratio for "DEBpresent vs. DEBabsent". RESULTS: From 1 September 2010 to 1 December 2013, we treated 625 AVF stenoses with endovascular techniques. In 86 of these stenoses, DEBs were used. Of the 86 DEB interventions, 37 were included for this study, 49 were excluded. In the study group, there was a significant difference in "re-intervention-free percentage at 12 months" before and after DEB: 19% vs. 69%. The hazard ratio for "DEBpresent" vs. "DEBabsent" was 0.23 (95% CI 0.14 to 0.36, p<0.001). CONCLUSIONS: This retrospective study suggests that DEBs significantly reduce re-intervention on recurrent in-stent AVF stenoses.

In vitro surrogate models to aid in the development of antivirals for the containment of foot-and-mouth disease outbreaks.

Foot-and-mouth disease virus (FMDV) is a highly pathogenic member of the genus Aphthovirus (family Picornaviridae) that is only to be manipulated in high-containment facilities, thus complicating research on and discovery of antiviral strategies against the virus. Bovine rhinitis B virus (BRBV) and equine rhinitis A virus (ERAV), phylogenetically most closely related to FMDV, were explored as surrogates for FMDV in antiviral studies. Although no efficient cell culture system has been reported so far for BRBV, we demonstrate that infection of primary bovine kidney cells resulted in an extensive but rather poorly-reproducible induction of cytopathic effect (CPE). Madin-Darby bovine kidney cells on the other hand supported viral replication in the absence of CPE. Antiviral tests were developed for ERAV in Vero A cells employing a viral RNA-reduction assay and CPE-reduction assay; the latter having a Z' factor of 0.83±0.07. The BRBV and ERAV models were next used to assess the anti-aphthovirus activity of two broad-spectrum antiviral agents 2'-C-methylcytidine (2CMC) and ribavirin, as well as of the enterovirus-specific inhibitor enviroxime. The effects of the three compounds in the CPE-reduction (ERAV) and viral RNA-reduction assays (BRBV and ERAV) were comparable. Akin to 2CMC, compound A, a recently-discovered non-nucleoside pan-serotype FMDV inhibitor, also inhibited the replication of both BRBV and ERAV, whereas enviroxime was devoid of activity. The BRBV and ERAV surrogate models reported here can be manipulated in BSL-2 laboratories and may facilitate studies to unravel the mechanism of action of novel FMDV inhibitors.