Hiren Mistry

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.

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.

Autogenous Brachial—Brachial Fistula for Vein Access. Haemodynamic Factors Predicting Outcome and 1 Year Clinical Data

UNLABELLED Two-stage autogenous brachial vein-brachial artery access (ABBA) has been proposed as an option where adequate superficial vein is not available for the creation of conventional haemodialysis fistulae. METHODS This report depicts the clinical outcome of a series of 17 consecutive patients who underwent ABBA in a single centre. Of the 17 patients, nine had had at least one previous arterioventricular (AV) fistula or graft, and eight were new to haemodialysis. Patencies were assessed using the Kaplan-Meier survival analysis. RESULTS In 14 patients, the brachial vein was transposed (82%) and the time to transposition ranged from 4 to 26 weeks (median time: 6 weeks). The functional patency rate was 45.75% at 12 months. After stage one, all fistulas that went on to develop well had a brachial vein flow of at least 900 ml min(-1), and this was significantly higher than in fistulas that failed to develop (p=0.005). The maturation rate in our study was 65% and the median time to cannulation of the fistula was 8 weeks from the stage 1. Of the 17 patients, 12 (71%) experienced at least one complication. Ten (59%) demonstrated moderate-to-severe stenoses; eight of which necessitated angioplasty and/or percutaneous mechanical thrombolysis. CONCLUSIONS ABBA was characterised by a high incidence of complications and a long period to achieve maturation. Despite close monitoring and a high rate of secondary interventions, the patency rate was low. With this experience, we now only consider it an alternative in patients without adequate superficial veins, who have had failed grafts or where there is a very high risk of infection.

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.

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.

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.

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 postoperative 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.

Importance of Pedal Arch in Treatment of Critical Limb Ischaemia

The revascularization of patients with critical leg ischaemia (CLI) is essential for limb salvage and healing tissue loss. Both infrainguinal bypass surgery and angioplasty are established techniques in the treatment of these patients. The healing of tissue loss is dependent on several factors, but re-establishing direct blood flow is mandatory to achieve this process. The role of the pedal arch in the treatment of patients with CLI has not been fully studied. The quality of the pedal arch could impact on the ability of a successful revascularization in healing tissue loss, as well as the long-term durability of both surgical and radiological treatment of patients with CLI.

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.