Is intra-operative blood flow predictive for early failure of radiocephalic arteriovenous fistula?

Background. For over 50 years, radiocephalic wrist arteriovenous fistulae (RCAVF) have been the primary and best vascular access for haemodialysis. Nevertheless, early failure due to thrombosis or non-maturation is a major complication resulting in their abandonment. This prospective study was designed to investigate the predictive value of intra-operative blood flow on early failure of primary RCAVF before the first effective dialysis. Methods. We enrolled patients undergoing creation of primary RCAVF for haemodialysis based on the pre-operative ultrasound vascular mapping discussed in a multidisciplinary approach. Intra-operative blood flow measurement was systematically performed once the anastomosis had been completed using a transit-time ultrasonic flowmeter. During the follow-up, blood flow was estimated by colour flow ultrasound at various intervals. Any events related to the RCAVF were recorded. Results. Autogenous RCAVFs (n = 58) in 58 patients were constructed and followed up for an average of 30 days. Thrombosis and non-maturation occurred in eight (14%) and four (7%) patients, respectively. The intra-operative blood flow in functioning RCAVFs was significantly higher compared to non-functioning RCAVFs (230 vs 98 mL/min; P = 0.007), as well as 1 week (753 vs 228 mL/min; P = 0.0008) and 4 weeks (915 vs 245 mL/min, P < 0.0001) later. Blood flow volume measurements with a cut-off value of 120 mL/min had a sensitivity of 67%, specificity of 75% and positive predictive value of 91%. Conclusions. Blood flow <120 mL has a good predictive value for early failure in RCAVF. During the procedure, this cut-off value may be used to select appropriately which RCAVF should be investigated in the operation theatre in order to correct in real time any abnormalit

Placement of Hemodialysis Catheters Through Stenotic or Occluded Central Thoracic Veins

A method for hemodialysis catheter placement in patients with central thoracic venous stenosis or occlusion is described and initial results are analyzed. Twelve patients, with a mean age of 63.2years (42-80years), with central venous stenosis or occlusion, and who required a hemodialysis catheter were reviewed. All lesions were confirmed by helical CT or phlebography. Five patients had stenosis while seven patients were diagnosed with an occlusion of thoracic central veins. All patients were asymptomatic, without sign of superior vena cava syndrome. After percutaneous transstenotic catheterization or guidewire-based recannalization in occlusions, a balloon dilatation was performed and a stent was placed, when necessary, prior to catheter placement. Technical success was 92%. Three patients had angioplasty alone and nine patients had angioplasty with stent placement. Dialysis catheters were successfully inserted through all recannalized accesses. No immediate complication occurred, nor did any patient develop superior vena cava syndrome after the procedure. The mean follow-up was 21.8months (range, 8-48months). Three patients developed a catheter dysfunction with fibrin sheath formation (at 7, 11, and 12months after catheter placement, respectively). Two were successfully managed by percutaneous endovascular approach and one catheter was removed. In conclusion, for patients with central venous stenosis or occlusion and those who need a hemodialysis catheter, catheter insertion can be reliably achieved immediately after endovascular recannalization with acceptable technical and long-term success rates. This technique should be considered as an alternative procedure for placing a new hemodialysis catheter through a patent vei

Cystathionine Gamma Lyase Is Regulated by Flow and Controls Smooth Muscle Migration in Human Saphenous Vein

The saphenous vein is the conduit of choice for bypass grafting. Unfortunately, the hemodynamic stress associated with the arterial environment of the bypass vein graft leads to the development of intimal hyperplasia (IH), an excessive cellular growth and collagen deposition that results in restenosis and secondary graft occlusion. Hydrogen sulfide (H2S) is a ubiquitous redox-modifying gasotransmitter that inhibits IH. H2S is produced via the reverse trans-sulfuration pathway by three enzymes: cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). However, the expression and regulation of these enzymes in the human vasculature remains unclear. Here, we investigated the expression of CSE, CBS and 3-MST in segments of native human saphenous vein and large arteries. Furthermore, we evaluated the regulation of these enzymes in vein segments cultured under static, venous (7 mmHg pressure) or arterial (100 mmHg pressure) pressure. CSE was expressed in the media, neointima and intima of the vessels and was negatively regulated by arterial shear stress. Adenoviral-mediated CSE overexpression or RNA interference-mediated CSE knock-down revealed that CSE inhibited primary human VSMC migration but not proliferation. We propose that high shear stress in arteriovenous bypass grafts inhibits CSE expression in both the media and endothelium, which may contribute to increased VSMC migration in the context of IH

Predictors and Consequences of Sac Shrinkage after Endovascular Infrarenal Aortic Aneurysm Repair

Background: Aneurysm shrinkage has been proposed as a marker of successful endovascular aneurysm repair (EVAR). We evaluated the impact of sac shrinkage on secondary interventions, on survival and its association with endoleaks, and on compliance with instructions for use (IFU). Methods: This observational retrospective study was conducted on all consecutive patients receiving EVAR for an infrarenal abdominal aortic aneurysm (AAA) using exclusively Endurant II/IIs endograft from 2014 to 2018. Sixty patients were entered in the study. Aneurysm sac shrinkage was defined as decrease &ge;5 mm of the maximum aortic diameter. Univariate methods and Kaplan&ndash;Meier plots assessed the potential impact of shrinkage. Results: Twenty-six patients (43.3%) experienced shrinkage at one year, and thirty-four (56.7%) had no shrinkage. Shrinkage was not significantly associated with any demographics or morbidity, except hypertension (p = 0.01). No aneurysm characteristics were associated with shrinkage. Non-compliance with instructions for use (IFU) in 13 patients (21.6%) was not associated with shrinkage. Three years after EVAR, freedom from secondary intervention was 85 &plusmn; 2% for the entire series, 92.3 &plusmn; 5.0% for the shrinkage group and 83.3 &plusmn; 9% for the no-shrinkage group (Logrank: p = 0.49). Survival at 3 years was not significantly different between the two groups (85.9 &plusmn; 7.0% vs. 79.0 &plusmn; 9.0%, Logrank; p = 0.59). Strict compliance with IFU was associated with less reinterventions at 3 years (92.1 &plusmn; 5.9% vs. 73.8 &plusmn; 15%, Logrank: p = 0.03). Similarly, survival at 3 years did not significantly differ between strict compliance with IFU and non-compliance (81.8 &plusmn; 7.0% vs. 78.6 &plusmn; 13.0%, Logrank; p = 0.32). Conclusion: This study suggests that shrinkage &ge;5 mm at 1-year is not significantly associated with a better survival rate or a lower risk of secondary intervention than no-shrinkage. In this series, the risk of secondary intervention regardless of shrinkage seems to be linked more to non-compliance with IFU. Considering the small number of patients, these results must be confirmed by extensive prospective studies

[Fibromuscular dysplasia and hypertension : beyond renal arteries].

Fibromuscular dysplasia (FMD) is a disease associated with abnormalities of the arterial wall of medium-sized arteries. These abnormalities can lead to stenosis or less frequently to dissections or aneurysms. FMD is probably more frequent than initially thought. Nowadays, it is often a chance finding during a radiologic exam. In symptomatic cases, poor organ perfusion due to stenosis, dissection or aneurysm rupture may lead to the diagnosis. The aim of this non-systematic review illustrated with a clinical case is to present our current knowledge of FMD and to highlight the necessity of a standardized and multidisciplinary work-up to improve management of affected patients and understanding of the disease