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Objectives: To study safety and efficacy of selective endovascular trans-arterial embolization (TAE) of renal angiomyolipoma (AML) in a 10-year period at a regional tertiary referral center in Denmark.Patients and methods: All 56 patients who underwent TAE of renal AML at Departments of Urology and Radiology, Copenhagen University Hospital - Rigshospitalet, Denmark, from 2009 to 2020 were included. Seven without preoperative and postoperative imaging were excluded, leaving 49 patients for analysis. From national electronic medical records, we retrieved patient characteristics, surgical data, and follow-up data. Tumor size at the time of embolization and during follow-up was compared using Student's paired t test. Estimated glomerular filtration rate (eGFR) pre- and post-embolization were compared using Wilcoxon rank sum test.Results: We included 49 patients of whom 4 had two tumors treated in the same TAE procedure. Median age was 50 years (interquartile range [IQR]: [29-67 years]), and the median follow-up time was 4.6 years [IQR: 3.0-6.7 years]. Post-embolization syndrome (PES) was experienced in 27 patients, and non-PES in 5 patients. Median length of hospital stay was 0 days [IQR, 0-1]. Postoperative Everolimus immunosuppressive treatment was offered to seven patients. Median tumor size was 6.0 cm [IQR: 4.6-7.9 cm] and was significantly reduced to 3.7 cm [IQR: 2.5-5.2 cm] after treatment (p < 0.001). Kidney function was not affected by TAE. Three deaths, not related to AML, were noted during follow-up.Conclusion: Embolization of AML was in this cohort effective to significantly reduce tumor size without serious adverse events and loss of renal function. TAE is a safe and efficacious treatment and the preferred minimally invasive treatment option of AML.

Median arcuate ligament syndrome (MALS) is the compression of the celiac artery (CA) by the median arcuate ligament. MALS can cause pseudoaneurysm of the gastroduodenal artery, which can lead to fatal bleeding. A 40-year-old male with no prior medical history presented with symptoms of upper gastrointestinal hemorrhage (UGIH). Severe duodenal bleeding was confirmed although endoscopic hemostasis was impossible and final hemostasis was achieved following a subsequent open duodenotomy. A postoperative computed tomographic angiography (CTA) visualized a significant CA stenosis, post-stenotic dilatation and an aneurysm on a jejunal branch artery. The patient underwent coiling of the gastroduodenal artery, gastroepiploic artery and two pancreaticoduodenal arterial branches. The patient was diagnosed with MALS and 6 months later underwent open resection of the median arcuate ligament. MALS should be considered as a rare cause of upper gastrointestinal bleeding. The literature and proposed treatments are discussed.

Non-invasive assessment is preferred for monitoring arteriovenous dialysis fistulas (AVFs). Vector concentration assesses flow complexity, which may correlate with stenosis severity. We determined whether vector concentration could assess stenosis severity in dysfunctional AVFs. Vector concentration was estimated in four stenotic phantoms at different pulse repetition frequencies. Spectral Doppler peak velocity and vector concentration were measured in 12 patients with dysfunctional AVFs. Additionally, 5 patients underwent digital subtraction angiography (DSA). In phantoms, vector concentration exhibited an inverse relationship with stenosis severity and was less affected by aliasing in severe stenoses. In nine stenoses of 5 patients undergoing DSA, vector concentration correlated strongly with stenosis severity (first stenosis: r = –0.73, p = 0.04; other stenoses; r = –0.69, p = 0.02) and mid-stenotic diameter (first stenosis: r = 0.87, p = 0.006; other stenoses: r = 0.70, p = 0.02) as opposed to peak velocities (p > 0.05). Vector concentration is less affected by aliasing in severe stenoses and correlates with DSA in patients with dysfunctional AVF.

The majority of patients with end stage renal disease are in hemodialysis, and therefore dependent on a well functioning vascular access. The arteriovenous fistula is the recommended access and in order to maintain and keep the fistula patent, regular monitoring of the function is necessary. The Ultrasound Dilution Technique is the reference method for volume flow measurement, but it only works in conjunction with the dialysis machine, and use is therefore restricted to dialysis sessions. Volume flow measurement with conventional Doppler ultrasound provides a non invasive, highly accessible solution, but is very challenging due to the angle dependency of the Doppler technique and the anatomy of the fistula. The angle independent vector ultrasound technique Transverse Oscillation provides a new and more intuitive way to measure volume flow in an arteriovenous fistula. In this paper the Transverse Oscillation has been used to measure volume flow directly on four patients’ arteriovenous fistulas, and the measurements were compared to subsequent measurements with the Ultrasound Dilution Technique. The results obtained with the Transverse Oscillation deviate -35.1 – 14.9 % from the reference method, and indicates potential for the method.

Purpose: The purpose of this study was to investigate if the immediate hemodynamic outcome of an endovascular intervention on a dysfunctional hemodialysis arteriovenous fistula is a prognostic factor for primary patency. Methods: This was a prospective observational study including 61 consecutive patients with dysfunctional arteriovenous fistulas referred to our endovascular unit. Patients were treated in accordance with institutional standard protocol including immediate pre- and post-interventional blood flow measurements using an intravascular catheter system. The primary endpoint was primary patency at 12 months in patients with an immediate post-interventional blood flow above or below 600 ml/min. Primary patency was estimated using the Kaplan-Meier method with the standard error of the estimate. Multivariate Cox regression analysis was used to study the effect of blood flow and other potential predictor variables. Results: Post interventional flow did not significantly influence primary patency (p = 0.76). Primary patency was found to be affected by having a history of previous intervention(s) (p = 0.008, hazard ratio 2.9) or low fistula age (P=.038, hazard ratio 0.97 [one-month increase]). Primary patency in group 1 (previous intervention(s)) was 34% ± 13% at 12 months. In group 2 (no previous intervention), primary patency at 12 months was 62% ± 9%. Conclusions: The results of this study do not provide scientific support for using the immediate hemodynamic outcome of an intervention as a prognostic factor for primary patency. Low fistula age and a history of previous intervention in particular were found to reduce primary patency significantly.

Purpose: To test the clinical performance of catheter-based thermodilution and Doppler ultrasound of the feeding brachial artery for blood flow measurements during hemodialysis vascular access interventions.Methods: Thirty patients with arteriovenous fistulas who underwent 46 interventions had access blood flow measured before and after every procedure. Two methods, catheter-based thermodilution and Doppler ultrasound, were compared to the reference method of ultrasound dilution. Catheter-based thermodilution and Doppler ultrasound were performed during the endovascular procedures while flow by ultrasound dilution was determined within three days of the procedure. The methods were compared using regression analysis and tested for systematic bias. Results: Failure to position the thermodilutional catheter correctly was observed in 8 out of 46 (17%) pre-intervention measurements. Post-intervention measurements and ultrasound measurements were feasible in all patients. The average level of agreement was good when comparing catheter-based thermodilution to ultrasound dilution. However, blood flow by ultrasound dilution may differ by ±130 mL/min (±22%) at a flow level of 600 mL/min by thermodilution. Results from Doppler ultrasound displayed a moderate level of agreement on average when compared to ultrasound dilution. Blood flow by ultrasound dilution may differ by ±160 mL/min (±27%) at a flow level of 600 mL/min by Doppler ultrasound. No systematic bias was detected by either method.Conclusions: On average, results from catheter-based thermodilution were more in agreement with results from the ultrasound dilution technique compared to Doppler ultrasound. However, considering the cost and the high technical failure rate of the thermodilutional system, we recommend the use of ultrasound.

Purpose: The purpose of this study was to perform bench and clinical testing of a catheter-based intravascular system capable of measuring blood flow in hemodialysis vascular accesses during endovascular procedures. Methods: We tested the Transonic ReoCath Flow Catheter System which uses the thermodilution method. A simulated vascular access model was constructed for the bench test. In total, 1960 measurements were conducted and the results were used to determine the accuracy and precision of the catheters, the effects of external factors (e.g., catheter placement, injection duration), and to test for systematic bias. In the clinical study, two interventional radiologists conducted a total of 250 measurements in 14 patients with arteriovenous fistulas to determine clinical precision and enable testing for bias between measurers.Results: Accuracy was excellent for both catheters with a high level of agreement between results from the ReoCath Flow Catheter System and the reference flowmeter. Clinical precision, expressed as the mean coefficient of variation, was 5.9% and 4.7% for the antegrade and retrograde catheters, respectively. Flow measurements were significantly affected by the distance between a stenosis and the tip of a retrograde catheter with the effect being proportional to the degree of stenosis. There was no systematic bias between measurers. Conclusions: The Reocath Flow Catheter System was found to be accurate and precise. Reliable results require careful attention to catheter placement. Blood flow measurements provide unique information on the hemodynamic status of a vascular access and have the potential to optimize results of interventions.

Cephalic arch stenosis is a known cause of hemodialysis access failure in patients with brachiocephalic fistulas (BCFs). Outcomes of endovascular treatment are affected by resistance of the stenosis to balloon dilation, a high vein rupture rate and the development of early restenosis. The purpose of this retrospective study was to report outcomes after cutting balloon angioplasty (CBA) of cephalic arch stenosis.