[The Cannulation of the Arteriovenous Fistula in the Presence of a Stent: Precautions, Risks, and Possibilities].

A proper management and tailored interventions represented two fundamental steps to ensure a long-term use of the arteriovenous fistula (AVF). AVF failure can be attributed to various factors, with stenosis being the most common cause. Different techniques are employed for treating complications, but percutaneous endovascular procedures are the most widely used. In addition to angioplasty (PTA), the possibility of utilizing stents, particularly stent grafts (SG), has further improved outcomes. However, the insertion of these devices involves commitment to a segment of the vessel, which may vary in length, making the indication necessitate a careful evaluation. The positioning of a stent graft indeed limits the space for needle insertion, and on the other hand, the cannulation of the device is considered off-label according to technical specification. This work addresses the issue of puncturing these devices. Alongside a rapid overview, we describe a clinical case of continuous cannulation of a multiply stented AVF, for over 9 years, which opens up the discussion about the possibility of long-term cannulation through proper planning.

Report on an Italian survey of 72 stuck hemodialysis catheters.

BACKGROUND: Reports of stuck hemodialysis catheters have been on the rise in recent years. Aim of this work is to report how this complication has been managed and the relative outcomes in a multicente Italian survey. METHODS: Since 2012, the Italian Society of Nephrology (SIN) Project Group of Vascular Access has collected data among nephrologists on this complication. Data regarding 72 cases of stuck tunnelled central venous catheter (tCVC) in 72 patients were retrieved thanks to this survey. RESULTS: In 11 patients (15%) the stuck catheter was directly buried or left in place. Sixty-one cases were managed through advanced removal techniques. Among these, 47 (77%) stuck tunnelled central venous catheters were successfully removed, while 14 (23%) failed to be withdrawn. Considering removed tCVCs, the use of endoluminal balloon dilatation alone or in combination with other tools showed a percentage of success of 88%. The removal procedure involved numerous specialists. Some complications occurred, such as breakage of the line or bleeding, and two cases of haemopericardium during an advanced procedure. CONCLUSION: The survey shows how the stuck catheter complication was managed in different ways, with conflicting results. When utilized, endoluminal balloon dilatation proved to be the most effective and most often utilized technique, while some cases had suboptimal management or failure. This underlines how delicate the procedure is, and the need for both precise knowledge of this complication and timely organization of removal attempts.

Successful 8-year use of Venous Window Needle Guide for deep arteriovenous fistula cannulation.

We describe the case of a patient who had been on hemodialysis for 8 years using a native arteriovenous fistula cannulated through the Venous Window Needle Guide™ device (VWING). The overall outcome was excellent and complication-free with intact state of the underlying vessel and a high degree of patient satisfaction. The patient was able to carry out self-cannulation without any difficulty almost from the very beginning. The current unavailability of VWING is a missed opportunity in the field of vascular access.

Acute renal infarction: a single center experience.

BACKGROUND: Acute renal infarction is a rare condition whose diagnosis is often delayed. Major risk factors include atrial fibrillation, valvular or ischemic heart disease, renal artery thrombosis/dissection and coagulopathy. METHODS: We reviewed the medical records of 18 patients admitted to our Nephrology Department between 1999 and 2015 for acute renal infarction diagnosed by computed tomography. Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy was performed in some patients during follow-up to assess parenchymal lesions and estimate differential kidney function. RESULTS: Mean age was 59.8 years. Major associated risk factors included hypertension (44 %), obesity (33 %), atrial fibrillation (28 %), peripheral vascular disease (17 %), smoking (17 %), prior thromboembolic event (11 %), diabetes (11 %), estroprogestinic therapy (11 %). Seventy-two percent of patients presented with flank pain. Mean serum creatinine was 1.2 ± 0.6 mg/dl. Acute kidney injury occurred as the initial manifestation in two patients. Patients were managed conservatively, with low molecular weight heparin (83 %) or aspirin (11 %). At the end of follow-up serum creatinine was 1.1 ± 0.3 mg/dl; one patient remained on chronic hemodialysis. 58 % of patients who underwent renal scintigraphy after a median of 8 months had a reduced contribution of the previously affected kidney to total renal function. CONCLUSION: Risk factors associated with the development of chronic kidney disease following renal infarction are unknown. In our subjects, renal function remained stable in all but one patient who developed end stage renal disease. Further studies should focus on etiology and evolution of kidney function in patients with acute renal infarction.

Venous Window Needle Guide for deep vessels and difficult arteriovenous fistula cannulation.

The Venous Window Needle Guide (VWING™) has recently been proposed for patients with difficult arteriovenous fistula (AVF) access for hemodialysis due to deep vessels or other cannulation-related problems. This totally subcutaneous titanium device is sutured onto the upper wall of the matured fistula and may facilitate cannulation by the button-hole technique. We describe our initial experience with nine implants in six patients with a cumulative follow-up of 83 months, and make some experience-based technical suggestions for implant and surveillance radiological imaging. The indication for implantation was deep vessel, previous failure of cannulation or unsuitable site for direct cannulation. No infectious complications were observed during follow-up and proper blood flow was constantly achieved. Some difficulties were occasionally encountered with regard to cannulation; nonetheless, patient satisfaction was not significantly affected. VWING seems to be an interesting option in some patients provided that surgical implantation is carefully carried out and preventive measures against infections are strictly observed.

"Two is better than one": a composite graft made of two different vascular prostheses for urgent hemodialysis access in a troublesome case.

BACKGROUND: Multiple failed hemodialysis access and poor vascular anatomy can jeopardize an end-stage renal disease patient's survival, frequently leading to the urgent need for rapid and durable new vascular access. In these circumstances, the extensive use of central venous catheters (CVC) can led to serious complications, such as infection, thrombosis, and often vessel scarring with obstruction of the central veins. More recently, new self-sealing prosthetic grafts may be cannulated within a few days after implantation, avoiding the need for extensive CVC. However, similar to all synthetic arteriovenous grafts (AVG), the new grafts are prone to rapid and aggressive venous neointimal hyperplasia (VNH), which is responsible for outflow stenosis and access thrombosis. Endoluminal sutureless anastomosis has been demonstrated to have better hemodynamics at the venous outflow with a supposed reduction of VNH, thus potentially improving graft patency. METHODS: We report a case of a successful creation of a composite prosthetic access in a patient with severe comorbidities and nearly complete exhaustion of all vascular sites and with the need for immediate access for hemodialysis. Two relatively novel vascular expanded polytetrafluoroethylene prostheses were used jointly in this patient for a brachial-axillary AVG to allow early cannulation and with the aim of being less vulnerable to outflow stenosis. A multilayer self-sealing graft and a graft with a nitinol reinforced section, which permits endoluminal sutureless anastomosis, were sewed together to create a unique prosthesis with both features. RESULTS: The composite graft was cannulated 48 hr after implantation and continued to function well at 10 months of follow-up without signs of venous stenosis. CONCLUSIONS: This simple technique allows the creation of a customized composite graft with self-sealing properties and improved hemodynamics at the venous outflow.

Dealing with stuck hemodialysis catheter: state of the art and tips for the nephrologist.

The term stuck catheter refers to the condition in which a catheter is not removable from a central vein using standard techniques. Although it is a rare complication, in the last few years it has been reported ever more frequently in hemodialysis due to the widespread use of tunneled catheters. Poor knowledge of the correct procedures and limited experience and training of the specialist in facing this problem are the main reasons for catheter internalization. Stuck catheter is often diagnosed by the nephrologist, who should be competent enough to manage this clinical complication. Among the many options for removing a stuck catheter from the fibrin sleeve, an interventional radiology approach, mainly with endoluminal balloon dilatation, probably provides the best solution. Vascular surgery should be reserved to selected cases in which percutaneous techniques have failed. Nephrologists must play a central role in organizing the treatment of this complication with other specialists in order to avoid making mistakes that may preclude future positive results.