Prophylactic distal revascularization and interval ligation procedure during femoral vein transposition fistula creation in patients at high risk for ischemic complications.

Femoral vein transposition arteriovenous fistula (FVt AVF) is a viable autologous option when upper extremity dialysis access sites have become compromised. High volume flow through the AVF can lead to ischemic complications, including steal syndrome (SS), and may threaten access and limb viability. Risk factors for SS include: age >60 years, female sex, diabetes, atherosclerosis, hypertension, and previous limb procedures. Two dialysis patients, who were at high risk for SS in their lower extremities as assessed during the preoperative evaluation for an elective FVt AVF, had a distal revascularization and interval ligation (DRIL) procedure concurrently performed. At 42 and 24 months from their respective surgeries, both patients are reliably using their lower extremity autologous access sites and have not developed any signs or symptoms of ischemia. DRIL may represent an effective surgical strategy that can prophylactically be used to minimize the incidence of ischemic complications during FVt AVF in carefully selected, high-risk patients.

Complex left profunda femoris vein to renal vein bypass for the management of progressive chronic iliofemoral occlusion.

Chronic occlusions of the inferior vena cava (IVC) and iliofemoral veins are long-term sequelae of deep venous thrombosis (DVT) that can lead to postthrombotic syndrome (PTS). Patients may present with a wide spectrum of signs and symptoms, ranging from mild discomfort and swelling to severe venous hypertension and ulcerations. We report a 68-year-old man who had a history of left lower extremity DVT after a laminectomy and who developed PTS with nonhealing ulcers. The patient underwent a cross-pubic femorofemoral venous bypass that failed to improve his clinical status. After unsuccessful endovascular attempts for recanalization of the iliofemoral segment, a profunda femoris to IVC bypass was performed. The symptoms recurred 2 years later. Venography revealed restenosis at the caval anastomosis that did not resolve by endovascular means. A surgical revision was performed, and given the quality of the IVC, a jump bypass was created to the left renal vein. The swelling improved and the ulcers healed completely. Twenty-eight months after the complex reconstructions, he remains ulcer-free with mild edema controlled with stockings. Venous reconstructions remain a viable option for patients with symptomatic and recalcitrant nonmalignant obstruction of the large veins.

Left common iliac artery to inferior vena cava abdominal wall arteriovenous graft for hemodialysis access.

We describe a novel arteriovenous graft configuration in the abdominal wall for hemodialysis in a 51-year-old woman with sickle cell disease. Upper extremity access sites were exhausted, and intrathoracic central veins occluded. Because of diminished quality of the left groin due to scar tissue from previous infected access, inadequate vasculature, and the presence of functional femoral catheter in the right groin with common iliac vein stenosis, we decided to create an arteriovenous graft from the left common iliac artery to the inferior vena cava. Adequate thrill and uneventful postoperative recovery was observed. At 4 months, the patient has been successfully using her graft.

Prevalence of variant brachial-basilic vein anatomy and implications for vascular access planning.

OBJECTIVE: To describe and increase understanding of the brachial-basilic vein anatomy that could impact planning of long-term hemodialysis access procedures. METHODS: Preoperative vein mapping was conducted in a cross-sectional, observational study in end-stage renal disease patients from August 2005 to May 2010. "Traditional" anatomic description with basilic-brachial junction at the axillary level with paired brachial veins was classified as "Type 1." Junctions observed at the mid or lower portions of the upper arm with duplication of the brachial vein above that level were classified as "Type 2." Junctions at the mid and lower portions of the upper arm with no duplication of the brachial vein above that level were classified as "Type 3." RESULTS: Two hundred ninety patients (mean age, 56 ± 17 years; 52% men) were observed and 426 arms mapped (221 right, 205 left). The prevalence of variations in venous arm anatomy was as follows: Type 1: 66%; Type 2: 17%; and Type 3: 17%. CONCLUSIONS: This study underscores the need for heightened awareness of upper arm venous variations and advocates the regular use of preoperative ultrasound imaging. We propose that recognition of Type 3 anatomy may have implications in access algorithm and planning.

Surgical management of hemodialysis-related central venous occlusive disease: a treatment algorithm.

BACKGROUND: Creation and preservation of dialysis access in patients with central venous occlusive disease (CVOD) is a complex problem. The surgical approach and decision-making process remains poorly defined. We evaluated our experience in the surgical management of hemodialysis-related CVOD. Surgical technique, demographics, complications, reinterventions, access function rates, and factors influencing morbidity and mortality were examined. METHODS: From January 2006 to May 2010, we performed a total of 1,703 dialysis access-related procedures, 1,021 arteriovenous fistulas (AVFs), 335 arteriovenous grafts (AVGs), and 314 access revisions including endovascular salvage procedures. Seventeen patients (10 women [58%] with a mean age of 44 ± 27 years) with CVOD who were not suitable for peritoneal dialysis or kidney transplant underwent 20 complex vascular access procedures. The indications were need for access creation in 14 cases (70%) and preservation in the remaining 6 (30%). Polytetrafluoroethylene (PTFE) was used for all surgical bypass grafts (BPG). All patients had previously undergone multiple access surgeries and had failed percutaneous interventions for CVOD. RESULTS: The surgical planning centered on finding venous outflow for an arteriovenous (AV) access; central venous reconstructions were necessary in 10 (50%) cases (seven [35%] in the thoracic central venous system and three [15%] in infradiaphragmatic vessels) and extracavitary venous BPG in two (10%) cases. Non-venous access options included axillary arterial-arterial chest wall BPG in five (25%) cases and brachial artery to right atrium BPG in three (15%). Technical success was achieved in all cases (100%). Mean follow-up was 14.1 months, both BPG and AV access patency rates were 66% at 6 months and overall average AV access function time was 9.2 months. Of these, 85% of patients were discharged home and following 19 (95%) cases they returned or improved their baseline functional status. One death occurred from multiorgan failure during the 30-day postoperative period. Four additional patients died within 3 years of the procedure secondary to nonsurgical-related comorbidities. CONCLUSION: The need for complex vascular accesses will continue as the number of patients with end-stage renal disease increases. CVOD is an access surgical challenge and with this article we propose a decision-making algorithm.

Pilocarpine improves recognition of nestmates in young honey bees.

Honey bees can distinguish nestmates from non-nestmates, directing aggressive responses toward non-nestmates and rarely attacking nestmates. Here we provide evidence that treatment with pilocarpine, a muscarinic agonist, significantly reduced the number of aggressive responses directed toward nestmates. By contrast, treatment with scopolamine, a muscarinic antagonist, significantly increased attacks on nestmates. Locomotor activity was not altered by these pharmacological treatments. When interpreted in light of known cholinergic pathways in the insect brain, our results provide the first evidence that cholinergic signaling via muscarinic receptors plays a role in olfaction-based social behavior in honey bees.

Use of position and feature cues in discrimination learning by the whiptail lizard (Cnemidophorus inornatus).

Animals use a variety of cue types to locate and discriminate objects. The ease with which particular cue types are learned varies across species and context. An enormous literature contains comparisons of spatial cue use to use of other cue types, but few experiments examine the ease with which various nonspatial cues are learned. In addition, few studies have examined cue use in reptiles. Thus, the authors compared whiptail lizards' (Cnemidophorus inornatus) ability to learn and reverse a discrimination using either position (left or right) or visual feature cues. Lizards learned and reversed the task using position cues faster and with greater accuracy than using feature cues.

Endovascular salvage of a right brachial artery-right atrium hemodialysis graft using a covered endoprosthesis.

Creation of a functional hemodialysis access in patients with exhausted peripheral access sites and concomitant central venous occlusive disease (CVOD) is a multifaceted challenge; often requiring complex, innovative solutions, not without their own complications. We present a 57-year-old hemodialysis patient with a history of hypercoagulable disorder and multiple failed arteriovenous accesses. Because of inadequate peripheral access sites and chronic occlusions in superior vena cava, brachiocephalic veins and inferior vena cava, in addition to multiple transhepatic catheter related issues; we decided to perform a right brachial artery to right atrium (RA) hemodialysis graft. The access was used without complications for 18 months at which point he had his first episode of thrombosis; open thrombectomy and percutaneous balloon angioplasty (PTA) at the atrial anastomosis were done with success. The following three months, he endured two more thrombectomies and PTAs. During the last intervention we performed an intravascular Ultrasound (IVUS) through the atrial anastomosis, which demonstrated stenosis; and the decision was made to extend the outflow anastomosis with a covered stent into the atrium. Therefore a 10 cm x 10 mm Viabahn stent-graft (W. L. Gore and Associates, Flagstaff, Ariz.) was deployed and post dilated with 8 mm balloon within the graft component. Repeat injection and Intravascular Ultrasound (IVUS) demonstrated significant improvement and free outflow. The brachial-RA hemodialysis graft could be use immediately and at 5 months has remained fully functional and no reinterventions have been necessary.

Surgical femorocaval bypass for recalcitrant iliofemoral venous occlusion to endovascular treatment.

Patients with chronic occlusion of iliac veins may present with symptoms ranging from mild discomfort to severe disability, including limb swelling, venous claudication, and ulceration. Endovascular treatment has emerged as first line of interventional therapy. Surgical venous-venous bypasses for the management of these patients in the era of endovascular therapy are rarely performed. These procedures are reserved only for patients with severe symptoms and long occlusive lesions that have failed previous endovascular interventions. We present a clinical scenario involving the use of femorocaval bypass to treat an iliofemoral occlusion recalcitrant to stenting, manifesting with severe lower extremity swelling and venous claudication. The surgical bypass resulted in significant improvement in the patient's clinical status.

Management of dialysis access-associated "steal" syndrome with DRIL procedure: challenges and clinical outcomes.

PURPOSE: The distal revascularization interval-ligation (DRIL) procedure has demonstrated efficacy in the management of dialysis access-associated steal syndrome (DASS); however, this has not been widely used because of concerns about complexity, risk of ligating a native artery, and lack of long-term outcomes. METHODS: Retrospective review of all patients with DASS who underwent DRIL procedure from March 2005 to August 2011. Indications, clinical considerations, bypass grafts, and patency rates were determined; complications, reinterventions, and factors influencing their outcomes were studied. RESULTS: 33 patients, (70% women, mean age of 56 ± 13) with DASS underwent a DRIL. Indications were ischemic pain alone in 12 (36%) patients, loss of neurologic function in 7 (21%), both ischemic pain and loss of neurologic function in 4 (12%) tissue loss in 7 (21%), pain during hemodialysis in one (3%), and "prophylactic" DRIL during a femoral vein transposition (FVt) fistula in two (6%). Technical success was 100%; Ischemic symptoms fully resolved by DRIL in 24 of the 31 symptomatic patients (77%) and during the follow up period DASS did not develop in the subjects we judged at high risk and underwent DRIL during FVt. One serious complication occurred because of early bypass thrombosis causing worsening hand gangrene requiring transmetacarpal amputation. The primary, assisted-primary, and secondary patency rates of the arterial bypass at 12 months were 65%, 75%, and 95% respectively. AV access primary, assisted-primary, and secondary patency were 29%, 85%, and 94% at 12 months. CONCLUSIONS: DRIL procedure is effective at relieving symptoms in carefully selected patients, but does have potential complications such as bypass failure and worsened ischemia. DASS remains a complex clinical entity in that it is not fully understood, and deserves further study.

The current status of endovascular repair of abdominal aortic aneurysms (EVAR).

Abdominal aortic aneurysms (AAA) affect close to a quarter of a million people in the United States every year. Intervention is designed to treat the AAA when the patient becomes symptomatic and to prevent the fatality associated with rupture. Physicians and patients should weigh the risks associated with intervention compared to the risk of rupture for the particular size of the aneurysm and the patient's comorbidities. Thus, the decision to intervene, especially in asymptomatic aneurysms, is mostly based on clinical judgment. Endovascular AAA repair (EVAR) is attractive in that it offers a minimally invasive approach that obviates a major abdominal procedure and cross-clamping of aorta. We report on the current affairs of the major clinical trails evaluating the outcomes of patients undergoing EVAR and describe the current devices available in the United States for endovascular repair.

Stimulation of muscarinic receptors mimics experience-dependent plasticity in the honey bee brain.

Honey bees begin life working in the hive. At approximately 3 weeks of age, they shift to visiting flowers to forage for pollen and nectar. Foraging is a complex task associated with enlargement of the mushroom bodies, a brain region important in insects for certain forms of learning and memory. We report here that foraging bees had a larger volume of mushroom body neuropil than did age-matched bees confined to the hive. This result indicates that direct experience of the world outside the hive causes mushroom body neuropil growth in bees. We also show that oral treatment of caged bees with pilocarpine, a muscarinic agonist, induced an increase in the volume of the neuropil similar to that seen after a week of foraging experience. Effects of pilocarpine were blocked by scopolamine, a muscarinic antagonist. Our results suggest that signaling in cholinergic pathways couples experience to structural brain plasticity.