The Venous Window Needle Guide, a hemodialysis cannulation device for salvage of uncannulatable arteriovenous fistulas.

BACKGROUND: Arteriovenous fistulas (AVFs) are recommended for hemodialysis access when possible. A noncannulatable but otherwise well functioning AVF leads to prolonged catheter dependency and frustration for the patient and the renal health care provider team. Difficult cannulation patients include obese individuals in whom cannulation sites are too deep, and others with vein segments that are short, tortuous, or otherwise difficult to palpate. The Venous Window Needle Guide for Salvage of AV Fistulae (SAVE) trial was designed to evaluate the efficacy and safety of the Venous Window Needle Guide (VWING; Vital Access Corp, Salt Lake City, Utah) device for salvage of such noncannulatable AVFs that are otherwise functional. METHODS: The SAVE study included patients with an established and otherwise mature AVF, in whom an additional procedure would otherwise be necessary to establish reliable cannulation. The VWING is a single-piece titanium device that allows repeated access of an AVF through a single puncture site (buttonhole technique). Inclusion criteria included mature AVFs 6.0 to 15.0 mm in depth with multiple failed attempts at cannulation or where the access could not be palpated. The devices were implanted subcutaneously and sutured to the anterior wall of the mature fistula. Study end points were reliable and successful cannulation and avoidance of adverse events during the 6-month follow-up, implant technical success, and clinical cannulation success. RESULTS: Enrollment included 54 patients at 11 trial sites with implantation of 82 VWING devices. Body mass index was 26 to 50 (median, 36), 40 (74%) patients were female, and age was 17 to 84 (median, 59) years. Forty (74%) individuals were diabetic. Thirty-three (61%) patients were white, 16 (30%) black, and 10 (18%) patients were Hispanic, Pacific Islander, or Native American. Three patients were excluded from data analysis for reasons unrelated to the device. Successful AVF access was achieved using the VWING in 49 (96%) of the 51 patients evaluated. The rate of device-related serious adverse events was 0.31 per patient-year; each event was resolved leaving the AVF functional. The rates of sepsis and study-related interventions were 0.04 and 0.65 per patient-year, respectively. There were no study-related deaths. One device was removed because of infection. The AVF survival rate at 6 months was 100%. The total number of study days was 9497 and the estimated number of device cannulations was 4238. CONCLUSIONS: The VWING was safe and effective in facilitating AVF cannulation for patients with an otherwise mature but noncannulatable fistula. Successful AVF access was achieved using the VWING in 49 (96%) of the 51 patients evaluated. The AVF survival rate at 6 months was 100%.

Optional filters in trauma patients: can retrieval rates be improved?

Prophylactic inferior vena cava interruption may be appropriate in trauma patients at risk for pulmonary embolism for whom anticoagulation is contraindicated. The Recovery filter is approved for removal up to 180 days from insertion. High retrieval rates need to be achieved before we can lower the threshold for inserting these filters prophylactically. The objective of this study was to evaluate the retrieval rate of the Recovery filter in this patient population and how it has influenced our practice. This is a retrospective study in which the records of 122 consecutive trauma patients in whom the Recovery filters were inserted between October 2003 and October 2005 were reviewed. Patients who had the new generation of this filter were excluded. All these filters were inserted with the intention of retrieval. We attempted to contact all these patients at 3 months. The technical factors associated with failure to retrieve these filters were reviewed. There were no complications related to filter insertion. Excluding six patients (4.9%) who expired from causes unrelated to the insertion procedure, 20 patients could not be reached (17.3%) and 21 patients declined retrieval (18.1%). The filters were considered permanent in 18 patients (15.5%) if they were not ambulatory or if they developed inferior vena cava occlusion. Inferior vena cava occlusion was diagnosed in four patients (5.5%). Seventy-three (62.9%) patients presented for follow-up and were evaluated by color venous duplex ultrasound. We attempted to retrieve the filters in 52 patients and were successful in 45 (86.5%). However, the total retrieval rate was 40.5%. All failures of retrieval were related to tilting of the filters or bending of the limbs. There were no complications related to the retrieval procedure. Insertion and retrieval of the Recovery inferior vena cava filter are safe. In spite of the thorough follow-up and the good success rate in retrieving the filters, the overall retrieval rate in this patient population is still low. This should be strongly considered at the time of insertion. Multiple factors were found to contribute. Attention to details in patient selection and follow-up as well as modifications in technique may improve the retrieval rate.

Outside-in signals delivered by matrix metalloproteinase-1 regulate platelet function.

Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade extracellular matrix proteins. These enzymes are implicated in a variety of physiological and pathological events characterized by extracellular matrix remodeling. Recent studies suggest that MMPs may have a signaling capacity, but direct evidence supporting this concept is lacking. In the present study, we demonstrate that outside-in signals delivered by exogenous MMP-1 (interstitial collagenase) markedly increase the number of tyrosine-phosphorylated proteins in platelets. Active MMP-1 also targets beta(3) integrins to areas of cell contact and primes platelets for aggregation. Examination of the endogenous enzyme demonstrated that activated platelets process latent MMP-1 into its active form. Neutralization of MMP-1 activity with MMP inhibitors or specific blocking antibodies markedly attenuates agonist-induced phosphorylation of intracellular proteins, movement of beta(3) integrins to cell contact points, and intercellular aggregation. The finding that MMP-1 is rapidly activated in platelets and controls functional responses identifies a new role for this metalloproteinase as a signaling molecule that regulates thrombotic events.

Native superficial femoral artery peripheral atherectomy site pseudoaneurysm: a case report.

A 45-year-old woman who presented with blue toe syndrome was treated with atherectomy for a focal plaque located in the superficial femoral artery. She subsequently developed a large pseudoaneurysm at the atherectomy site requiring multiple sequential endovascular procedures in order to maintain in-line blood flow to the foot. Pseudoaneurysm formation at native peripheral artery atherectomy site has not been reported previously. We discuss possible complications of atherectomy and the possible mechanism of pseudoaneurysm formation after atherectomy. We address the importance of understanding risks of these minimally invasive procedures along with planning follow-up duplex and potential bail-out tactics.

Simvastatin suppresses experimental aortic aneurysm expansion.

OBJECTIVE: Abdominal aortic aneurysm (AAA) formation is a result of inflammation and extracellular matrix (ECM) remodeling mediated by matrix metalloproteinases (MMPs). Hydroxymethylglutaryl-coenzyme A inhibitors (statins), although clinically used as lipid-lowering agents, have also been demonstrated to have anti-inflammatory effects. This study was designed to determine whether the hydroxymethylglutaryl-coenzyme A inhibitor simvastatin suppresses aneurysm formation in an elastase-induced rat AAA model. METHODS: Aneurysms were created in adult male Wistar rats by infusion of elastase into isolated infrarenal aortic segments. The rats were randomized to receive either simvastatin (n = 17) or placebo (n = 17) by gastric lavage daily starting the day before surgery. The rats were euthanized and the infrarenal aortas harvested on postoperative day 7. Aortic diameters were measured before infusion, immediately after infusion, and at the time of harvesting. Protein expression was measured by immunoblot analysis. Gene expression profiling using Affymetrix U34A rat genome chips was performed to identify changes in gene expression caused by simvastatin treatment. RESULTS: Mean aneurysm diameter was significantly less in the simvastatin treatment group compared with controls (3.4 +/- 0.08 mm vs 4.3 +/- 0.19 mm; P = .0001). MMP-9 and nuclear factor-kappaB protein levels were decreased in the aortas of simvastatin-treated animals. Gene microarray analysis revealed 315 genes with statistically significant changes in expression (P < .05) in the simvastatin group. Genes related to inflammation, ECM remodeling, and oxidative stress function were downregulated. These included genes for interleukin 1, interleukin 4, inducible nitric oxide synthase, P-selectin, platelet-derived growth factor alpha, tumor necrosis factor, and several chemokines. CONCLUSIONS: Simvastatin significantly suppresses experimental aneurysm expansion and reduces protein levels of MMP-9 and nuclear factor-kappaB. Gene array analysis provides evidence that several mediators of inflammation, matrix remodeling, and oxidative stress are downregulated by simvastatin treatment. This suggests that simvastatin inhibits AAA formation by blocking the expression of certain proinflammatory genes. Simvastatin may be useful as an adjuvant therapy to suppress the growth of small aneurysms.

Has the changing nature of vascular surgery adversely affected scholarly activity.

OBJECTIVE: Because of reduced reimbursement and introduction of endovascular techniques into practice, vascular surgeons have increased clinical commitments. Therefore we hypothesized that the scholarly productivity of vascular surgeons has decreased. Study design An author-based Medline search was carried out for members of the Society for Vascular Surgery (SVS). The search included the period from 1985 to 1989 (era 1) for members in 1990, and from 1995 to 1999 (era 2) for members in 2000. Citations were assigned a type: basic science, clinical, case report, letter, or other; and a topic: cardiac, vascular, endovascular, transplantation, or miscellaneous. The main outcome measures were the proportion of members who published in each era and the rates of publication among authors. RESULTS: For era 1, 7069 citations were identified for 529 members, and for era 2, 6823 citations were identified for 615 members. Four hundred forty-two members were cited in era 1 (84%), compared with 443 (72%) in era 2 (P =.01). A significantly smaller proportion of members published clinical research, case reports, and other publications, but not basic science or letters. Excluding unpublished members, there was a median of 11 total publications per author in each era. There were significant reductions in the proportion of members publishing papers related to cardiac (from 36% to 21%), transplantation (8% to 4%), and miscellaneous (43% to 31%) topics, and a significant increase in papers related to endovascular topics (from 19% to 28%) from era 1 to era 2. Moreover, there was a significant increase in median number of vascular (from 5 to 8) and endovascular (1 to 2) papers per published member. Further, the proportion of vascular and endovascular citations compared with total citations increased from 44% to 56% in era 1 and from 3% to 10% in era 2. On a yearly basis, there was a steady decrease in the number of citations throughout era 2, whereas the number of citations in era 1 was relatively constant. CONCLUSIONS: Academic productivity was maintained for individual members who published across both eras, but a smaller proportion of the SVS membership published in era 2. There was also a progressive reduction in the number of publications during the 1990s.

Severe coagulopathy following intraoperative use of topical thrombin.

This report describes a case of severe coagulopathy and bleeding related to the intraoperative use of topically applied thrombin. Commercial thrombin preparations contaminated with bovine factor V have been shown to stimulate the production of antibodies directed against factor V. These antibodies can cause coagulopathy. Our patient developed antibodies against factor V after intraoperative exposure to topical thrombin. The resulting antibody-mediated depletion of factor V caused a severe and refractory coagulopathy. Vascular surgeons should be aware that the use of topical bovine thrombin can cause severe coagulopathy.

Common femoral artery injury secondary to bicycle handlebar trauma.

Blunt trauma from bicycle handlebars is associated with well-described injuries of the abdominal viscera. These injuries result from the forceful compression of the relatively immobile abdominal organs between the handlebar end and the vertebral bodies. The common femoral artery is also immobile as it passes anterior to the superior pubic ramus, rendering this vessel susceptible to a similar mechanism of injury. We have treated two children who sustained thrombosis of the common femoral artery caused by bicycle handlebar trauma. The lack of familiarity with this uncommon mode of injury may contribute to delayed diagnosis and increased morbidity. We therefore wish to draw attention to this mechanism of injury.