Description and outcomes of a simple surgical technique to treat thrombosed autogenous accesses

ObjectiveOwing to the difficulty of removing acute and chronic thrombus from autogenous accesses (AA) by standard surgical and endovascular techniques, many surgeons consider efforts to salvage a thrombosed AA as being futile. We describe a simple technique to extract acute and chronic thrombus from a failed AA. This technique involves making an incision adjacent to the anastomosis, directly extracting the arterial plug, and manually milking thrombus from the access. This report details the outcomes of a series of thrombosed AAs treated by surgical thrombectomy/intervention using this technique for manual clot extraction.MethodsA total of 146 surgical thrombectomies/interventions were performed in 102 patients to salvage a thrombosed AA. Mean follow-up was 15.6 months. Office, hospital, and dialysis unit records were reviewed to identify patient demographics, define procedure type, and determine functional patency rates. Kaplan-Meier survival analysis was used to estimate primary and secondary functional patency rates.ResultsComplete extraction of thrombus from the AA was achieved in 140 of 146 cases (95%). The studied procedure itself was technically successful in 127 cases (87%). Reasons for failure were the inability to completely extract thrombus from the AA in six, failed angioplasty due to long segment vein stenosis or sclerosis in seven or vein rupture in two, and central vein occlusion in one. Three failures occurred for unknown causes ≤3 days of successful thrombectomy. No single factor analyzed (age, sex, race, diabetes status, access type or location) was associated with technical failure. The estimated primary and secondary functional patency rates were 27% ± 5% and 61% ± 6% at 12 months.ConclusionsThe manual clot extraction technique described in this report effectively removed acute and chronic thrombus from failed AAs. Its use, combined with an intervention to treat the underlying cause for AA failure, significantly extended access durability

Prosthetic thigh arteriovenous access: outcome with SVS/AAVS reporting standards

AbstractPurposeDifferences in the reporting methods of results for arteriovenous (AV) access can dramatically affect apparent outcome. To enable meaningful comparisons in the literature, the Society for Vascular Surgery and the American Association for Vascular Surgery (SVS/AAVS) recently published reporting standards for dialysis access. The purpose of the present study was to determine infection rates, patency rates, and possible predictive factors for prosthetic thigh AV access outcomes with the reporting standards of the SVS/AAVS.MethodsA retrospective analysis was performed of all patients who underwent placement of thigh AV access by the Surgical Teaching Service at Greenville Memorial Hospital between 1989 and 2001. Outcomes were determined based on SVS/AAVS Standards for Reports Dealing with AV Accesses. The rate of revision per year of access patency was also determined; this end point more accurately reflects the true cost and morbidity associated with AV access than do patency or infection rates alone.ResultsOne hundred twenty-five polytetrafluoroethylene thigh AV accesses were placed in 100 patients. Nine accesses were excluded from the study, six because there was no patient follow-up and 3 as a result of deaths unrelated to the access procedure and which occurred less than 30 days after access placement. There were six (4%) late access-related deaths. There were 18 (15%) early access failures, related to infection in 14 cases (12%), thrombosis in three cases (2%), and steal in one case (1%). Early failure was more common in patients with diabetes mellitus (P = .036). The primary and secondary functional patency rates were 19% and 54%, respectively, at 2 years. Infection occurred in 48 (41%) accesses. The patency and infection rates were not influenced by patient age, gender, body mass index, or diabetes mellitus. The median number of interventions per year of access patency was 1.68, and this outcome was positively correlated with body mass index (P < .001).ConclusionsProsthetic AV access in the thigh is associated with higher morbidity compared with that reported for the upper extremity, and should be considered only if no upper extremity AV access option is available. Early access failure and the requirement for an increased number of interventions to reestablish and maintain access patency are more common in patients with diabetes mellitus and obesity. The number of interventions per year of access patency is a valuable end point when assessing the outcome of AV access procedures

Extension of the Chiral Perturbation Theory Meson Lagrangian to Order P6P^6

We have derived the most general chirally invariant Lagrangian ${\cal L}_6$ for the meson sector at order $p^6$. The result provides an extension of the standard Gasser-Leutwyler Lagrangian ${\cal L}_4$ to one higher order, including as well all the odd intrinsic parity terms in the Lagrangian. The most difficult part of the derivation was developing a systematic strategy so as to get all of the independent terms and eliminate the redundant ones in an efficient way. The 'equation of motion' terms, which are redundant in the sense that they can be transformed away via field transformations, are separated out explicitly. The resulting Lagrangian has been separated into groupings of terms contributing to increasingly more complicated processes, so that one does not have to deal with the full result when calculating $p^6$ contributions to simple processes.Comment: 59 pages in LaTex, using RevTex macro, TRIUMF preprint TRI-PP-94-6

Preoperative clinical factors predict postoperative functional outcomes after major lower limb amputation: An analysis of 553 consecutive patients

BackgroundDespite being a major determinant of functional independence, ambulation after major limb amputation has not been well studied. The purpose, therefore, of this study was to investigate the relationship between a variety of preoperative clinical characteristics and postoperative functional outcomes in order to formulate treatment recommendations for patients requiring major lower limb amputation.MethodsFrom January 1998 through December 2003, 627 major limb amputations (37.6% below knee amputations, 4.3% through knee amputations, 34.5% above knee amputations, and 23.6% bilateral amputations) were performed on 553 patients. Their mean age was 63.7 years; 55% were men, 70.2% had diabetes mellitus, and 91.5% had peripheral vascular disease. A retrospective review was performed correlating various preoperative presenting factors such as age at presentation, race, medical comorbidities, preoperative ambulatory status, and preoperative independent living status, with postoperative functional endpoints of prosthetic usage, survival, maintenance of ambulation, and maintenance of independent living status. Kaplan-Meier survival curves were constructed and compared by using the log-rank test. Odds ratios (OR) and hazard ratios (HR) with 95% confidence intervals were constructed by using multiple logistic regressions and Cox proportional hazards models.ResultsStatistically significant preoperative factors independently associated with not wearing a prosthesis in order of greatest to least risk were nonambulatory before amputation (OR, 9.5), above knee amputation (OR, 4.4), age >60 years (OR, 2.7), homebound but ambulatory status (OR, 3.0), presence of dementia (OR, 2.4), end-stage renal disease (OR, 2.3), and coronary artery disease (OR, 2.0). Statistically significant preoperative factors independently associated with death in decreasing order of influence included age ≥70 years (HR, 3.1), age 60 to 69 (HR, 2.5), and the presence of coronary artery disease (HR, 1.5). Statistically significant preoperative factors independently associated with failure of ambulation in decreasing order of influence included age ≥70 years (HR, 2.3), age 60 to 69 (HR, 1.6), bilateral amputation (HR, 1.8), and end-stage renal disease (HR, 1.4). Statistically significant preoperative factors independently associated with failure to maintain independent living status in decreasing order of influence included age ≥70 years (HR, 4.0), age 60 to 69 (HR, 2.7), level of amputation (HR, 1.8), homebound ambulatory status (HR, 1.6), and the presence of dementia (HR, 1.6).ConclusionsPatients with limited preoperative ambulatory ability, age ≥70, dementia, end-stage renal disease, and advanced coronary artery disease perform poorly and should probably be grouped with bedridden patients, who traditionally have been best served with a palliative above knee amputation. Conversely, younger healthy patients with below knee amputations achieved functional outcomes similar to what might be expected after successful lower extremity revascularization. Amputation in these instances should probably not be considered a failure of therapy but another treatment option capable of extending functionality and independent living

Transcatheter Implantation of the MONARC Coronary Sinus Device for Mitral Regurgitation 1-Year Results From the EVOLUTION Phase I Study (Clinical Evaluation of the Edwards Lifesciences Percutaneous Mitral Annuloplasty System for The Treatment of Mitral Regurgitation)

ObjectivesThis study sought to assess the safety and efficacy of transcatheter valve annuloplasty in patients with mitral regurgitation (MR).BackgroundMitral regurgitation is associated with a worsened prognosis in patients with dilated cardiomyopathy. Surgical mitral annuloplasty reduces the septal-lateral dimension of the mitral annulus resulting in improved leaflet coaptation with a reduction in regurgitation. Percutaneous annuloplasty with the MONARC device (Edwards Lifesciences, Irvine, California) implanted within the coronary sinus is designed to reduce mitral regurgitation through a similar mechanism.MethodsA total of 72 patients with MR grade ≥2 were enrolled at 8 participating centers in 4 countries. Clinical evaluation and transthoracic echocardiography were performed at baseline and at 3, 6, and 12 months. Multislice cardiac computed tomography and coronary angiography were performed at baseline and 3 months.ResultsThe MONARC device was implanted in 59 of 72 patients (82%). The primary safety end point (freedom from death, tamponade, or myocardial infarction at 30 days) was met in 91% of patients at 30 days and in 82% at 1 year. Computed tomography imaging documented passage of the great cardiac vein over an obtuse marginal artery in 55% of patients and was associated with angiographic coronary artery compression in 15 patients and myocardial infarction in 2 patients (3.4%). At 12 months, a reduction in MR by ≥1 grade was observed in 50.0% of 22 implanted patients with matched echocardiograms and in 85.7% of 7 patients with baseline MR grade ≥3.ConclusionsImplantation of the MONARC device in the coronary sinus is feasible and may reduce MR. However, coronary artery compression may occur in patients in whom the great cardiac vein passes over a coronary artery, necessitating strategies in future studies to avoid this occurrence

Genetic Determinants of Circulating Sphingolipid Concentrations in European Populations

Sphingolipids have essential roles as structural components of cell membranes and in cell signalling, and disruption of their metabolism causes several diseases, with diverse neurological, psychiatric, and metabolic consequences. Increasingly, variants within a few of the genes that encode enzymes involved in sphingolipid metabolism are being associated with complex disease phenotypes. Direct experimental evidence supports a role of specific sphingolipid species in several common complex chronic disease processes including atherosclerotic plaque formation, myocardial infarction (MI), cardiomyopathy, pancreatic beta-cell failure, insulin resistance, and type 2 diabetes mellitus. Therefore, sphingolipids represent novel and important intermediate phenotypes for genetic analysis, yet little is known about the major genetic variants that influence their circulating levels in the general population. We performed a genome-wide association study (GWAS) between 318,237 single-nucleotide polymorphisms (SNPs) and levels of circulating sphingomyelin (SM), dihydrosphingomyelin (Dih-SM), ceramide (Cer), and glucosylceramide (GluCer) single lipid species (33 traits); and 43 matched metabolite ratios measured in 4,400 subjects from five diverse European populations. Associated variants (32) in five genomic regions were identified with genome-wide significant corrected p-values ranging down to 9.08 x 10(-66). The strongest associations were observed in or near 7 genes functionally involved in ceramide biosynthesis and trafficking: SPTLC3, LASS4, SGPP1, ATP10D, and FADS1-3. Variants in 3 loci (ATP10D, FADS3, and SPTLC3) associate with MI in a series of three German MI studies. An additional 70 variants across 23 candidate genes involved in sphingolipid-metabolizing pathways also demonstrate association (p = 10(-4) or less). Circulating concentrations of several key components in sphingolipid metabolism are thus under strong genetic control, and variants in these loci can be tested for a role in the development of common cardiovascular, metabolic, neurological, and psychiatric diseases

Pentoxifylline as an adjunct therapy in children with cerebral malaria

<p>Abstract</p> <p>Background</p> <p>Pentoxifylline (PTX) affects many processes that may contribute to the pathogenesis of severe malaria and it has been shown to reduce the duration of coma in children with cerebral malaria. This pilot study was performed to assess pharmacokinetics, safety and efficacy of PTX in African children with cerebral malaria.</p> <p>Methods</p> <p>Ten children admitted to the high dependency unit of the Kilifi District Hospital in Kenya with cerebral malaria (Blantyre coma score of 2 or less) received quinine plus a continuous infusion of 10 mg/kg/24 hours PTX for 72 hours. Five children were recruited as controls and received normal saline instead of PTX. Plasma samples were taken for PTX and tumour necrosis factor (TNF) levels. Blantyre Coma Score, parasitemia, hematology and vital signs were assessed 4 hourly.</p> <p>Results</p> <p>One child (20%) in the control group died, compared to four children (40%) in the PTX group. This difference was not significant (p = 0.60). Laboratory parameters and clinical data were comparable between groups. TNF levels were lower in children receiving PTX.</p> <p>Conclusions</p> <p>The small sample size does not permit definitive conclusions, but the mortality rate was unexpectedly high in the PTX group.</p

Challenges and Prospects in Ocean Circulation Models

We revisit the challenges and prospects for ocean circulation models following Griffies et al. (2010). Over the past decade, ocean circulation models evolved through improved understanding, numerics, spatial discretization, grid configurations, parameterizations, data assimilation, environmental monitoring, and process-level observations and modeling. Important large scale applications over the last decade are simulations of the Southern Ocean, the Meridional Overturning Circulation and its variability, and regional sea level change. Submesoscale variability is now routinely resolved in process models and permitted in a few global models, and submesoscale effects are parameterized in most global models. The scales where nonhydrostatic effects become important are beginning to be resolved in regional and process models. Coupling to sea ice, ice shelves, and high-resolution atmospheric models has stimulated new ideas and driven improvements in numerics. Observations have provided insight into turbulence and mixing around the globe and its consequences are assessed through perturbed physics models. Relatedly, parameterizations of the mixing and overturning processes in boundary layers and the ocean interior have improved. New diagnostics being used for evaluating models alongside present and novel observations are briefly referenced. The overall goal is summarizing new developments in ocean modeling, including: how new and existing observations can be used, what modeling challenges remain, and how simulations can be used to support observations.Peer reviewe