Carotid bypass using the Gore Hybrid Vascular Graft as a rescue technique for on-table failed carotid endarterectomy.

Carotid endarterectomy (CEA) remains the "gold standard" for atherosclerotic lesions involving the carotid bifurcation. Carotid bypass grafting using either polytetrafluoroethylene or long saphenous vein is a suitable alternative technique, especially in challenging endarterectomy and on-table failed CEA. We report our initial experience of using the Gore Hybrid Vascular Graft (W. L. Gore & Associates, Flagstaff, Ariz) in six patients as a rescue technique when standard CEA failed.

Diabetics are less likely to develop thoracic aortic dissection: a 10-year single-center analysis.

BACKGROUND: Diabetes mellitus (DM) is an acknowledged risk factor for atherosclerosis, and diabetics are more likely to have hypertension. Atherosclerosis and hypertension are risk factors for aortic dissection. However, recent studies have shown that DM is associated with changes in aortic wall collagen. In this retrospective study we assess the relationship between DM and thoracic aortic dissection (TAD). METHODS: Patients with a diagnosis of thoracic aortic dissection during the last 10 years were identified from our hospital records. The prevalence of DM in Stanford type A and B TAD was compared with that of two age- and gender-matched control groups. For every diabetic dissection case, 10 controls were selected from the hospital data. RESULTS: Two hundred nineteen patients (median age 61 years, male:female ratio 145:74) were identified with TAD, comprising 131 type A dissections and 88 type B dissections. Only 3 of 131 (2.3%) type A aortic dissections were diabetics, whereas, in control group 1, 241 of 1310 (18.4%) were diabetics and, in control group 2, 116 of 1310 (8.9%) were diabetics [odds ratios: 0.1 (0.03-0.32) and 0.24 (0.07-0.76), respectively] (P = 0.0001 and 0.007, respectively). Similarly, only 2 of 88 (2.3%) type B aortic dissections were diabetics, whereas 228 of 880 (26.0%) and 102 of 880 (11.6%) were diabetics in groups 1 and 2 [odds ratios: 0.07 (0.02-0.27) and 0.18 (0.04-0.73), respectively] (P = 0.0001 and 0.0035, respectively). All these odds ratios were statistically significant (P < 0.01). CONCLUSIONS: Patients with thoracic aortic dissection are less likely to be diabetic. Although we identified association only, not causality, it is possible that DM, or its treatment, has a protective effect against aortic dissection.

Options for end stage vascular access: Translumbar catheter, arterial-arterial access or right atrial graft?

BACKGROUND: Running out of vascular access for dialysis is thankfully rare, but despite this, most units will have a number of patients with few options and in a precarious state. The increasing longevity of dialysis patients portends more patients will reach minimal access options. End stage vascular access is poorly defined but classification may enable assessment and comparison of treatment options. Three options for patients with end stage access are a central venous catheter through a translumbar or transhepatic route, arterial-arterial prosthetic loop or a right atrial graft. AIMS: The aims of this study are to provide a structured review of evidence for these procedures to allow application and guide practice for patients with end stage vascular access. METHODS: A standardised search of published literature was performed of relevant studies. In addition, the references cited in those papers were assessed for any further available articles. All study types were included and reviewed by two authors independently. Primary outcomes were patient survival and secondary patency rate at 3 and 12 months. Secondary outcomes were long-term patency rates, mean time to cannulation and complications such as access dysfunction, thrombosis and infection. SUMMARY: Based on the available evidence, it would appear that arterial-arterial prosthetic loop is a definitive option for maintaining dialysis access in patients with no more arteriovenous access options. Translumbar and transhepatic dialysis catheters may offer short- and medium-term options and right atrial grafts may also be suitable as an option where arterial-arterial prosthetic loop is unsuitable.

Recurrent refractory arterial thromboembolism associated with the Janus kinase 2 V617F mutation.

We report two patients with peripheral vascular disease requiring multiple bilateral radiologic and surgical interventions, and whose disease was unresponsive to conventional anticoagulation and antiplatelet therapy. Although thrombocytosis was only intermittent, analysis of the Janus kinase 2 (JAK2) gene revealed a V617F mutation, thus confirming the presence of an underlying occult myeloproliferative disorder. We propose that JAK2 mutation analysis be considered in patients with recurrent, unexplained arterial events to identify those with occult myeloproliferative disorders.

Aneurysms in vascular access: state of the art and future developments.

A master class was held at the Vascular Access at Charing Cross (VA@CX2017) conference in April 2017 with invited experts and active audience participation to discuss arteriovenous (AV) vascular access aneurysms, a serious and common complication of vascular access (VA). The natural history of aneurysms in VA is poorly defined, and although classifications exist they are not uniformly applied in studies or clinical practice. True and pseudo aneurysms of AV access occur. Whilst an AV fistula by definition is an abnormal dilatation of a blood vessel, an agreed definition of 18 mm, or 3 times accepted maturation diameter, is proposed. The mechanism of aneurysmal dilatation is unknown but appears to be a combination of excessive external remodeling, wall changes due to injury, and obstruction of outflow. Diagnosis of AV aneurysms is based on physical examination and ultrasound. Venography and cross-sectional imaging may assist and be required for the investigation of outflow stenosis. Treatment of pseudo aneurysms and true aneurysms of VA (AVA) is not evidence-based, but relies on clinical experience and available facilities. In many AVA, a conservative approach with surveillance is suitable, although intervals and modalities are unclear. Avoidance of rupture is imperative and preemptive treatment should aim for access preservation, ideally with avoidance of prosthetic materials. Different techniques of aneurysmorrhaphy are described with good results in published series. Although endovascular approaches and stenting are described with good short-term results, issues with cannulation of stented areas occur and, while possible, this is not recommended, and long-term access revision is recommended.

A novel classification system for autogenous arteriovenous fistula aneurysms in renal access patients.

INTRODUCTION: Arteriovenous fistulae (AVFs) constructed for hemodialysis access are prone to aneurysmal degeneration. This can lead to life-threatening sequelae such as aneurysmal rupture. The literature includes various guidelines on the management of certain aspects of access-related aneurysm formation; however, no classification system exists to guide reporting or prognostication. We aimed to create a universally acceptable classification for these aneurysms and establish guidance about their management. METHODS: We clinically examined, duplex scanned, and photographed all of the autologous arteriovenous fistulae in our local renal failure population in January 2010 in order to categorize morphology. We then followed up the cohort for 2 years prospectively to assess outcomes, primarily of rupture or surgical intervention for bleeding. RESULTS: A total of 344 patients were included (292 currently needling their fistula and 52 with low creatinine clearance awaiting dialysis). In all, 43.5% of dialyzed patients had aneurysmal fistulae. We propose a classification system as follows: type 1a: dilated along the length of the vein; type 1b: postanastomotic aneurysm; type 2a: classic "camel hump"; type 2b: combination of type 2a and 1b; type 3: complex; and type 4: pseudoaneurysm. Six fistulae needed emergency surgery for bleeding in the 2-year follow-up period and 5 of these were type 2 aneurysms. The remaining one was in the nonaneurysmal group, although it had become aneurysmal by the time it bled. CONCLUSION: Type 1 aneurysms are much commoner in patients who have not yet needled their fistula and have a relatively innocuous course although type 1a aneurysms should be monitored for high flow and physiological consequences thereof. Type 2 aneurysms are associated with needling of AVFs. They are at significant risk of rupture and need to be monitored carefully or treated prophylactically.

Diabetes mellitus and aortic aneurysm rupture: a favorable association?

INTRODUCTION: Recent reports suggest that diabetic patients are relatively unlikely to have abdominal aortic aneurysms (AAAs). This retrospective study assesses the relationship between diabetes mellitus (DM) and aortic aneurysm rupture. METHODS: Patients with a diagnosis of any aortic aneurysm during a 10-year period were identified from our records. Patients with diagnoses of aortic aneurysm (thoracic, thoracoabdominal, and abdominal, treated and untreated) were included. Patients with nonatheromatous aneurysms (transection, dissection, mycotic, or isolated iliac) were excluded. RESULTS: In all, 1830 patients with nonruptured aneurysms and 232 ruptured aneurysms were included giving a total of 2062 patients with aortic aneurysms (abdominal, thoracic, and thoracoabdominal). Of these 1830, 225 (12.3%) patients with nonruptured aneurysm were diabetic; however, only 13 (5.6%) of the 232 patients with ruptured aortic aneurysm were diabetic (odds ratio [OR] = 0.42; confidence interval [CI]: 0.23-0.75, P = .004). Considering only those with AAAs, 184 (12.4%) of the 1482 nonruptured AAA were diabetic; however, only 12 (6.4%) of the 188 patients with ruptured AAA were diabetic (OR = 0.48 [CI: 0.26-0.88], P = .02). In this study group, the odds of dying due to aneurysm rupture in the diabetic group are significantly lower compared to the nondiabetic groups (OR = 0.31 [CI: 0.13-0.69], P = .004), despite the finding that diabetic patients had almost the same life expectancy as nondiabetic patients (DM, 73 years [67-80] vs non-DM, 75 years [68-82] P = .23). CONCLUSIONS: Diabetic patients with aortic aneurysms are significantly less likely to present with rupture or to die from aneurysm rupture when compared to nondiabetic patients with aortic aneurysms. We have identified association only, not causality. However, it is plausible that DM, or the treatment of DM, may have a protective effect on aortic aneurysm rupture.

Early outcomes of the intraluminal flow guard device for secondary renal access.

PURPOSE: The Flixene Intraluminal Flow Guard (IFG) is a novel arteriovenous graft for use in complex renal access patients. The IFG is a PTFE graft with a covered nitinol stent at the venous end implanted into the axillary vein rather than anastomosed. The purported benefits are improved hemodynamic flow in the vein with reduced neointimal hyperplasia. Our primary aim was to assess its early patency and complications. Our center is the first to publish early outcomes. METHODS: All patients on whom we would have otherwise performed a standard brachial-axillary graft from April to November 2011 were instead given an IFG graft if they were suitable and consented. The only exclusion criteria was an axillary vein size under 5.5 mm as this would not accommodate the intraluminal stent graft. Data were collected prospectively and follow-up was identical to our usual graft surveillance. RESULTS: A total of 12 patients (mean age 64, mean follow-up 393 days) had IFG grafts implanted during the study period. There were no exclusions and all patients consented. All patients were having secondary access following previous failed fistulae or grafts and no patient had an autogenous hemodialysis option. On average each patient had already had 1.1 previous ipsilateral access procedures. Mean operating time was 109 minutes. Functional patency at one year was 65.6%, with a mean functional patency of 162 days. There was only one early complication (wound hematoma) and one graft infection requiring explantation. CONCLUSIONS: The IFG device provides an alternative to standard brachial-axillary grafts and brings similar early patency and complication profile. Continued monitoring of outcomes, however, is required to determine long-term results.

Axillary-axillary interarterial chest loop graft for successful early hemodialysis access.

PURPOSE: Obtaining adequate vascular access in patients undergoing chronic hemodialysis therapy can be demanding, particularly for those in whom all peripheral venous options have been exhausted. CASE: We present a case of a 46-year-old woman with a history of complex vascular access for end-stage renal failure for whom there was no remaining possibility of venous access and had reached a palliative stage. We implanted an emergency loop axillary-axillary interarterial early needling graft. Post-operatively, the patient made a quick and uneventful recovery, resuming hemodialysis after only six days with no interventions necessary up to four months follow-up. To the best of our knowledge, this is the first dedicated case report describing the successful implantation of an axillary-axillary interarterial chest loop graft to re-establish access in a patient with exhausted options. CONCLUSION: We recommend the use of this technique to surgeons who find themselves in comparable situations in the future.

A large aneurysm in an arterio-venous fistula for renal access in a pregnant young woman.

Pregnancy is known to increase the risk of aneurysm formation, likely by a combination of histological changes in vessel walls associated with the hormones of pregnancy and the haemodynamic changes to the circulation. To our knowledge this is the first case of a pregnant woman with a brachial-cephalic arterio-venous fistula (AVF) that had never been needled for haemodialysis, yet became hugely aneurysmal during her pregnancy.

Duplex ultrasound volumetric flow analysis before and after hemodialysis in patients with brachio-cephalic fistulae.

PURPOSE: The United Kingdom Renal Association recommends duplex ultrasound to monitor arteriovenous fistula (AVF) flow rates during surveillance. Significant flow rate changes should prompt further investigation or treatment to avoid a failing fistula. Hemodialysis is known to alter the hemorrheologic and physiologic factors with a potential impact on measured flow rates. The aim of this study was to determine the difference in flow rate measured with duplex ultrasound before and after a single hemodialysis session in patients with brachial-cephalic fistulae. METHODS: Patients with brachial-cephalic AVFs in our dialysis populations who were undergoing regular hemodialysis without recent intervention (less than six weeks) were invited to participate. Flow measurements were made pre-and post-hemodialysis using a Zonare ultrasound machine. The vascular scientist was always blinded to the pre-hemodialysis flow. RESULTS: A total of 157 patients were identified with brachial-cephalic fistulae. Following exclusions, 119 patients were eligible. However, a further 58 were excluded because they declined or did not attend leaving 61 patients in the study. Paired t test showed a statistically significant reduction in flow rate of 105 mL/min (P=0.026) post-hemodialysis which equates to a -6.9% change in flow (95% C.I. -12.7 to -0.8%). Bland-Altman analysis showed limits of flow rate agreement between -599 mL/min and +810 mL/min (+/-1.96 s.d.). CONCLUSIONS: Whilst we have shown a statistically significant change in flow rate post-hemodialysis, this is small and should be taken in the context of previously accepted interobserver variability. Therefore, the practical and financial considerations of implementing an AVF surveillance programme are likely to outweigh the minimal benefit of consistency that would be enabled by strict protocol of pre-hemodialysis flow measurements.

Vascular access outcomes in HIV-positive patients.

PURPOSE: There is a limited source of information about vascular access outcomes in HIV-positive patients in the literature. Previous studies have shown autogenous arteriovenous fistulae (AVF) to have similar cumulative survival rates in HIV-positive and negative patients but functional patency has not been assessed. The primary aim of this study was to investigate functional patency of AVFs in HIV-positive patients. METHODS: A retrospective case-control study identifying 17 HIV-positive patients with AVFs under the care of renal services at Kings College Hospital, London was undertaken. Seventeen HIV-negative controls were matched for age, sex, ethnicity, and co-morbidities. Comparisons were made for pre-operative vein diameter, primary and functional patencies, and post-operative complications. RESULTS: No statistically significant difference was seen for functional patency between AVFs in the HIV-positive and control groups (P=.078). Complications were experienced by five HIV-positive patients (29.4%) and nine of the control group (52.9%). These included aneurysms and pseudoaneurysms for both groups. The difference in pre-operative vein diameter was not significant (P=.102), although only five of the HIV-positive patients had pre-operative vein diameters >=2.5 mm (45.5%) compared to twelve of the controls (75%). CONCLUSIONS: This study reveals that there is no statistically significant difference between the functional patency of autogenous AVFs in HIV-positive patients compared to HIV-negative controls. With less than half of the HIV-positive patients having pre-operative vein diameters >=2.5 mm, this suggests that it is still worth creating AVFs in patients with sub-optimal veins considering the known poorer patency with non-autogenous fistulae.

Comparison among transposed brachiobasilic, brachiobrachial arteriovenous fistulas and Flixene™ vascular graft.

OBJECTIVE: To compare the outcomes of 3 upper arm access types: transposed brachiobasilic arteriovenous fistula (BBAVF), autogenous brachial vein-brachial artery access (ABBA), and a new type of ePTFE graft (Flixene™ graft) (AVG), in a consecutive series of patients treated in a tertiary centre. METHODS: A prospective, computerized access database was analysed retrospectively to identify all patients undergoing BBAVF, ABBA, or AVG between January 1, 2008, and December 31, 2009. RESULTS: A total of 108 patients were identified; of whom 45 had BBAVF, 15 ABBA, and 48 ePTFE brachioaxillary AVG. Early failure was similar in all 3 groups. The 18-month functional patency rates for the ABBAs, BBAVFs, and grafts were 27%, 51%, and 55%, respectively. The median time to first use for AVGs was significantly shorter (p<0.0001). Complications were not more frequent in AVGs than ABBAs and BBAVFs (p=0.127). The total number of access interventions was similar between the AVG and ABBA groups (p=0.58), but it was significantly higher in the AVG group compared with the BBAVF group (p<0.0001). CONCLUSIONS: This study supports the current recommendations of the NKF Kidney Disease Outcomes Quality Initiative for using BBAVFs as third choice after radiocephalic and brachiocephalic arteriovenous fistulas. We also showed good results with a new type of prosthetic graft (Flixene™ graft) that allows cannulation within days of implantation. We now favour the use of this graft instead of basilic vein transposition in elderly patients with short life expectancy and urgent need of renal access.

High brachial artery bifurcation is associated with failure of brachio-cephalic autologous arteriovenous fistulae.

OBJECTIVE: Although European Best Practice Guidelines on vascular access recommend universal pre-operative duplex scan in patients receiving brachio-cephalic (BC) arteriovenous fistulae (AVF), this is not widespread practice. Furthermore, cadaveric and angiographic studies suggest that variation in upper limb arterial anatomy is common. Our aim was to investigate the prevalence of high brachial artery bifurcation (HB) and its impact on BC AVF patency. METHODS: A retrospective analysis of consecutive autologous BC AVF created over an 18-month period (January 2008 to June 2009). Patients with high bifurcations identified at duplex scan were compared with a control group who had normal bifurcations. All patients were followed up at 1, 6 and 12 weeks post-operatively. The study endpoint was AVF patency. RESULTS: One hundred and five autologous BC AVF procedures were performed in our institution, of which 29 (27.6%) were identified as having a high brachial bifurcation on pre-operative duplex scan. The bifurcation was axillary in six patients and located at the proximal, middle and distal third of the humerus in nine, seven and seven patients, respectively. The actuarial functional patency rate was 53.2% (standard error = 9.6%) in the HB group and 76.2% (standard error = 4.9%) in the control group (log-rank test, p=0.027). CONCLUSIONS: These data show that aberrant brachial artery anatomy is both common (12%) and a predictor of autologous BC AVF failure. These data support the universal use of pre-AVF duplex scanning.