Classification of Chimney EVAR-Related Endoleaks: Insights from the PERICLES Registry

Juxtarenal aortic aneurysms (JAAs) pose significant challenges for endovascular aneurysm repair (EVAR). A short or absent infrarenal neck typically excludes standard EVAR as a viable or reasonable treatment option. In this context, the use of chimney grafts (chEVAR) is gaining in popularity and applicability. These grafts are designed to course in the aortic lumen outside the main stent-graft to maintain normal perfusion to the involved target branches. As such, they may represent a promising and less resource-intensive option for management of JAAs. However, this technical strategy is not without challenges of its own, particularly the inevitable creation of \u201cgutters\u201d that result from the interaction of the chimney graft with the main aortic stent-graft. These gutters can become a conduit for type Ia endoleak formation, hence they represent the Achilles\u2019 heel of chEVAR. Current reports point to a relatively wide-ranging incidence (0%\u201313%) of type Ia endoleaks related to chEVAR. The PERICLES Registry collected the global transatlantic experience of 13 European and US vascular centers reporting 517 patients with complex aneurysms treated with EVAR and chimney parallel grafts. Overall, 6% of PERICLES chEVAR patients had a type Ia endoleak at completion angiography, but the rate of persistent endoleaks was only 2.9% at a mean 17.1 months of follow-up. Close review of the postoperative computed tomography angiograms of these persistent endoleak patients revealed distinct types and patterns of chEVAR-related type Ia endoleaks and form the basis of a new classification proposed herein. It is hoped that these observations will lead to development of new treatment algorithms for effective management of chimney-related endoleaks and, in some cases, to prevent them from occurring in the first place

The emergency use of endografts in the carotid circulation to control hemorrhage in potentially contaminated fields

We report our experience with the use of endoluminal grafts to control emergency bleeding in two patients with tracheoinnominate fistulas and three patients with carotid blowouts. Systemic infectious complications were not seen. However, rebleeding occurred in one patient, and extensive stent coverage to control bleeding was required in a second. Survival was usually limited by the patient’s cancer. There was one long-term survivor without cancer whose tracheostomy was placed for neurologic compromise. A review of the literature for similar cases identified 18 additional endografts placed for carotid blowout and 3 placed for tracheoinnominate fistulas. Overall, infectious complications occurred in only two patients, whereas rebleeding occurred in eight patients. On the basis of these findings, we believe that endografts are useful to control emergency hemorrhage in these two pathologies because treatment is usually palliative, given the poor survival secondary to the underlying disease. However, more extensive graft coverage may be necessary considering the erosive nature of these processes

Comparison of LED and Conventional Fluorescence Microscopy for Detection of Acid Fast Bacilli in a Low-Incidence Setting

INTRODUCTION: Light emitting diode fluorescence microscopes have many practical advantages over conventional mercury vapour fluorescence microscopes, which would make them the preferred choice for laboratories in both low- and high-resource settings, provided performance is equivalent. METHODS: In a nested case-control study, we compared diagnostic accuracy and time required to read slides with the Zeiss PrimoStar iLED, LW Scientific Lumin, and a conventional fluorescence microscope (Leica DMLS). Mycobacterial culture was used as the reference standard, and subgroup analysis by specimen source and organism isolated were performed. RESULTS: There was no difference in sensitivity or specificity between the three microscopes, and agreement was high for all comparisons and subgroups. The Lumin and the conventional fluorescence microscope were equivalent with respect to time required to read smears, but the Zeiss iLED was significantly time saving compared to both. CONCLUSIONS: Light emitting diode microscopy should be considered by all tuberculosis diagnostic laboratories, including those in high income countries, as a replacement for conventional fluorescence microscopes. Our findings provide support to the recent World Health Organization policy recommending that conventional fluorescence microscopy be replaced by light emitting diode microscopy using auramine staining in all settings where fluorescence microscopy is currently used

A multi-level spectral deferred correction method

The spectral deferred correction (SDC) method is an iterative scheme for computing a higher-order collocation solution to an ODE by performing a series of correction sweeps using a low-order timestepping method. This paper examines a variation of SDC for the temporal integration of PDEs called multi-level spectral deferred corrections (MLSDC), where sweeps are performed on a hierarchy of levels and an FAS correction term, as in nonlinear multigrid methods, couples solutions on different levels. Three different strategies to reduce the computational cost of correction sweeps on the coarser levels are examined: reducing the degrees of freedom, reducing the order of the spatial discretization, and reducing the accuracy when solving linear systems arising in implicit temporal integration. Several numerical examples demonstrate the effect of multi-level coarsening on the convergence and cost of SDC integration. In particular, MLSDC can provide significant savings in compute time compared to SDC for a three-dimensional problem

Integrating an N -Body Problem with SDC and PFASST

Vortex methods for the Navier–Stokes equations are based on a Lagrangian particle discretization, which reduces the governing equations to a first-order initial value system of ordinary differential equations for the position and vorticity of N particles. In this paper, the accuracy of solving this system by time-serial spectral deferred corrections (SDC) as well as by the time-parallel Parallel Full Approximation Scheme in Space and Time (PFASST) is investigated. PFASST is based on intertwining SDC iterations with differing resolution in a manner similar to the Parareal algorithm and uses a Full Approximation Scheme (FAS) correction to improve the accuracy of coarser SDC iterations. It is demonstrated that SDC and PFASST can generate highly accurate solutions, and the performance in terms of function evaluations required for a certain accuracy is analyzed and compared to a standard Runge–Kutta method

Iliac artery recanalization of chronic occlusions to facilitate endovascular aneurysm repair

Concurrent iliac occlusion and abdominal aortic aneurysm is rare. Traditionally, the endovascular approach to these patients has consisted of aortouniiliac devices combined with femoral–femoral bypass. With improved facility of endovascular techniques, standard bifurcated endografts represent an alternative option in these patients. This study examined outcomes of patients undergoing iliac recanalization and traditional bifurcated endovascular aneurysm repair in the face of access vessel occlusion.Outcomes of patients at three academic tertiary referral centers who underwent attempted iliac recanalization of chronic iliac occlusions and concurrent endovascular aneurysm repair of an infrarenal aortic aneurysm were retrospectively reviewed. Patients with acute iliac thrombosis and those with severely stenotic (but patent) iliac vessels were excluded.During a 6-year period, 15 occluded iliac arteries were treated in 14 patients (13 men). Mean age was 67.8 years (range, 52-80 years). Primary indication for intervention was disabling claudication in four patients, size of abdominal aortic aneurysm in nine, and symptomatic aneurysm in one. Seven patients presented with a unilateral common iliac artery (CIA) occlusion, four with a unilateral external iliac artery (EIA) occlusion, three with a unilateral combined CIA and EIA occlusion, and one with bilateral CIA occlusions. Stents had been placed previously in two of the occluded CIAs and in one of the occluded EIAs. Average length of the occluded segment was 7.5 cm (range, 2-17 cm). The occluded CIAs and EIAs had mean diameters of 8.6 and 5.7 mm, respectively. Successful recanalization was achieved in 14 of the 15 vessels (93.3%). One EIA ruptured during recanalization but was easily controlled with a covered stent. A re-entry device was used in two cases. Overall, 13 bifurcated devices were successfully implanted. Bilateral iliac occlusions in one patient were recanalized. One Talent (Medtronic, Santa Rosa, Calif), eight Excluder (W. L. Gore and Associates, Flagstaff, Ariz), and four Zenith (Cook Medical, Bloomington, Ind) devices were used. Mean length of stay was 2.3 days (range, 1-6 days). No major perioperative complications or deaths occurred. During a mean follow-up of 28.2 months (range, 1-86 months), there was 100% primary patency of successfully recanalized iliac arteries. Aneurysm sac size decreased from a mean of 5.1 cm (range, 3.1-7.6 cm) preoperatively to 4.4 cm (range, 2.8-7.1 cm) at follow-up. No aneurysms grew or ruptured. Three type II endoleaks occurred, one of which required coiling at 15 months. Two late deaths occurred: one at 36 months secondary to complications from a coronary artery bypass graft/mitral valve replacement and one at 34 months from a myocardial infarction.The use of bifurcated endovascular devices after recanalization of an occluded iliac system is technically feasible and durable at midterm follow-up. This technique re-establishes aortoiliac inflow to both lower extremities, obviates the need for extra-anatomic bypass, and may preserve hypogastric perfusion in some patients

Iliac artery recanalization of chronic occlusions to facilitate endovascular aneurysm repair

Concurrent iliac occlusion and abdominal aortic aneurysm is rare. Traditionally, the endovascular approach to these patients has consisted of aortouniiliac devices combined with femoral–femoral bypass. With improved facility of endovascular techniques, standard bifurcated endografts represent an alternative option in these patients. This study examined outcomes of patients undergoing iliac recanalization and traditional bifurcated endovascular aneurysm repair in the face of access vessel occlusion.Outcomes of patients at three academic tertiary referral centers who underwent attempted iliac recanalization of chronic iliac occlusions and concurrent endovascular aneurysm repair of an infrarenal aortic aneurysm were retrospectively reviewed. Patients with acute iliac thrombosis and those with severely stenotic (but patent) iliac vessels were excluded.During a 6-year period, 15 occluded iliac arteries were treated in 14 patients (13 men). Mean age was 67.8 years (range, 52-80 years). Primary indication for intervention was disabling claudication in four patients, size of abdominal aortic aneurysm in nine, and symptomatic aneurysm in one. Seven patients presented with a unilateral common iliac artery (CIA) occlusion, four with a unilateral external iliac artery (EIA) occlusion, three with a unilateral combined CIA and EIA occlusion, and one with bilateral CIA occlusions. Stents had been placed previously in two of the occluded CIAs and in one of the occluded EIAs. Average length of the occluded segment was 7.5 cm (range, 2-17 cm). The occluded CIAs and EIAs had mean diameters of 8.6 and 5.7 mm, respectively. Successful recanalization was achieved in 14 of the 15 vessels (93.3%). One EIA ruptured during recanalization but was easily controlled with a covered stent. A re-entry device was used in two cases. Overall, 13 bifurcated devices were successfully implanted. Bilateral iliac occlusions in one patient were recanalized. One Talent (Medtronic, Santa Rosa, Calif), eight Excluder (W. L. Gore and Associates, Flagstaff, Ariz), and four Zenith (Cook Medical, Bloomington, Ind) devices were used. Mean length of stay was 2.3 days (range, 1-6 days). No major perioperative complications or deaths occurred. During a mean follow-up of 28.2 months (range, 1-86 months), there was 100% primary patency of successfully recanalized iliac arteries. Aneurysm sac size decreased from a mean of 5.1 cm (range, 3.1-7.6 cm) preoperatively to 4.4 cm (range, 2.8-7.1 cm) at follow-up. No aneurysms grew or ruptured. Three type II endoleaks occurred, one of which required coiling at 15 months. Two late deaths occurred: one at 36 months secondary to complications from a coronary artery bypass graft/mitral valve replacement and one at 34 months from a myocardial infarction.The use of bifurcated endovascular devices after recanalization of an occluded iliac system is technically feasible and durable at midterm follow-up. This technique re-establishes aortoiliac inflow to both lower extremities, obviates the need for extra-anatomic bypass, and may preserve hypogastric perfusion in some patients

A Hybrid Godunov Method for Radiation Hydrodynamics

From a mathematical perspective, radiation hydrodynamics can be thought of as a system of hyperbolic balance laws with dual multiscale behavior (multiscale behavior associated with the hyperbolic wave speeds as well as multiscale behavior associated with source term relaxation). With this outlook in mind, this paper presents a hybrid Godunov method for one-dimensional radiation hydrodynamics that is uniformly well behaved from the photon free streaming (hyperbolic) limit through the weak equilibrium diffusion (parabolic) limit and to the strong equilibrium diffusion (hyperbolic) limit. Moreover, one finds that the technique preserves certain asymptotic limits. The method incorporates a backward Euler upwinding scheme for the radiation energy density and flux as well as a modified Godunov scheme for the material density, momentum density, and energy density. The backward Euler upwinding scheme is first-order accurate and uses an implicit HLLE flux function to temporally advance the radiation components according to the material flow scale. The modified Godunov scheme is second-order accurate and directly couples stiff source term effects to the hyperbolic structure of the system of balance laws. This Godunov technique is composed of a predictor step that is based on Duhamel's principle and a corrector step that is based on Picard iteration. The Godunov scheme is explicit on the material flow scale but is unsplit and fully couples matter and radiation without invoking a diffusion-type approximation for radiation hydrodynamics. This technique derives from earlier work by Miniati & Colella 2007. Numerical tests demonstrate that the method is stable, robust, and accurate across various parameter regimes.Comment: accepted for publication in Journal of Computational Physics; 61 pages, 15 figures, 11 table

Early and efficient detection of Mycobacterium tuberculosis in sputum by microscopic observation of broth cultures.

Early, efficient and inexpensive methods for the detection of pulmonary tuberculosis are urgently needed for effective patient management as well as to interrupt transmission. These methods to detect M. tuberculosis in a timely and affordable way are not yet widely available in resource-limited settings. In a developing-country setting, we prospectively evaluated two methods for culturing and detecting M. tuberculosis in sputum. Sputum samples were cultured in liquid assay (micro broth culture) in microplate wells and growth was detected by microscopic observation, or in Löwenstein-Jensen (LJ) solid media where growth was detected by visual inspection for colonies. Sputum samples were collected from 321 tuberculosis (TB) suspects attending Bugando Medical Centre, in Mwanza, Tanzania, and were cultured in parallel. Pulmonary tuberculosis cases were diagnosed using the American Thoracic Society diagnostic standards. There were a total of 200 (62.3%) pulmonary tuberculosis cases. Liquid assay with microscopic detection detected a significantly higher proportion of cases than LJ solid culture: 89.0% (95% confidence interval [CI], 84.7% to 93.3%) versus 77.0% (95% CI, 71.2% to 82.8%) (p = 0.0007). The median turn around time to diagnose tuberculosis was significantly shorter for micro broth culture than for the LJ solid culture, 9 days (interquartile range [IQR] 7-13), versus 21 days (IQR 14-28) (p<0.0001). The cost for micro broth culture (labor inclusive) in our study was US $4.56 per sample, versus US$11.35 per sample for the LJ solid culture. The liquid assay (micro broth culture) is an early, feasible, and inexpensive method for detection of pulmonary tuberculosis in resource limited settings

Performance of LED-Based Fluorescence Microscopy to Diagnose Tuberculosis in a Peripheral Health Centre in Nairobi.

Sputum microscopy is the only tuberculosis (TB) diagnostic available at peripheral levels of care in resource limited countries. Its sensitivity is low, particularly in high HIV prevalence settings. Fluorescence microscopy (FM) can improve performance of microscopy and with the new light emitting diode (LED) technologies could be appropriate for peripheral settings. The study aimed to compare the performance of LED-FM versus Ziehl-Neelsen (ZN) microscopy and to assess feasibility of LED-FM at a low level of care in a high HIV prevalence country