Endovascular repair of bleeding aortoenteric fistulas: A 5-year experience

AbstractPurpose: Aortoenteric fistula (AEF) is an uncommon but catastrophic complication that can occur either primarily or after aortic reconstruction. Untreated, it is uniformly fatal. Conventional surgical management is associated with a perioperative mortality rate of 25% to 90% and frequent major complications. We reviewed our experience with the endovascular treatment of both primary and secondary AEFs in an effort to determine whether endovascular repair is a less morbid alternative to traditional surgical treatment in select patients. Methods: In a 5-year period, seven high-risk patients who had bleeding and an AEF documented by means of radiology or endoscopy (2 primary, 5 secondary) were treated with coil embolization (1) or placement of an endovascular aortic stent graft (3 aortouniiliac, 2 tube, 1 bifurcated). One patient underwent computed tomography (CT)-guided percutaneous catheter drainage of an infected perigraft collection. The average follow-up period was 27 months (range, 11-66 months), and follow-up consisted of physical examination, complete blood count, and contrast-enhanced helical CT scanning at 3, 6, and 12 months and yearly thereafter. All patients were treated with intravenous antibiotics perioperatively and were prescribed life-long oral antibiotics on discharge. Results: There was one perioperative death (14%) caused by fungal sepsis. Persistent sepsis after stent-graft placement necessitated laparotomy and bowel resection in one patient. One patient had three bouts of recurrent sepsis that were successfully treated with a change of antibiotic. There were three late deaths (43%) unrelated to the procedure or AEF. Three patients (43%) were alive and well an average of 36 months (range, 23-67 months) after the procedure, with no clinical or radiologic evidence of recurrent bleeding or infection. Conclusion: Endovascular management of AEFs is technically feasible and may be the preferred treatment in select patients with bleeding and no signs of sepsis. In the setting of gross infection, it may also be considered in high-risk patients as a bridge to more definitive treatment after hemodynamic stabilization and optimization. (J Vasc Surg 2001;34:1055-9.

Endovascular stent grafting in the presence of aortic neck filling defects: Early clinical experience

AbstractObjective: Although endovascular grafts have been increasingly applied to the treatment of abdominal aortic aneurysms, their use in clinical trials is limited by well-defined anatomical exclusion criteria. One such criterion is the presence of thrombus within the infrarenal neck of an aneurysm, which is thought to (1) prevent the creation of a permanent watertight seal between the graft and the vessel wall, resulting in an endoleak; (2) contribute to stent migration; and (3) increase the risk of thromboembolism. This article summarizes our experience with endovascular abdominal aortic aneurysm exclusion in 19 patients with large aortic aneurysms, significant medical comorbidities, and apparent thrombus extending into the pararenal aortic neck. Methods: Of 268 patients undergoing abdominal aortic aneurysm repair, 19 (7%; 17 men; mean age, 71 years) demonstrated computed tomographic and angiographic evidence of intramural filling defects at the level of the aortic neck. In no instance did these filling defects extend above the renal arteries. Endovascular grafting was performed through use of a balloon-expandable Palmaz stent and an expanded polytetrafluoroethylene graft, delivered and deployed under fluoroscopic guidance. Follow-up at 3, 6, and 12 months and annually thereafter was performed with computed tomography and duplex ultrasound scan. Results: Spiral computed tomography and aortography revealed an irregular flow-limiting defect, occupying up to 75% of the aortic circumference, in every case. The mean aneurysm size, aortic neck diameter, and neck length before the procedure were 6.1, 2.43, and 1.4 cm, respectively; the mean aortic neck diameter after the procedure was 2.61 cm. No primary endoleaks were observed after graft insertion, and no delayed endoleaks have been detected during follow-up, which ranged from 7 to 48 months (mean, 23 months). In one patient, an asymptomatic renal artery embolus was detected on immediate follow-up computed tomography, and in another patient, an asymptomatic posterior tibial embolus occurred. Conclusion: No primary endoleaks, endograft migration, or significant distal embolization were observed after endografting in patients with aortic neck thrombus. The deployment of the fenestrated portion of the stent, above the thrombus and across the renal arteries, allows for effective renal perfusion, graft fixation, and exclusion of potential mural thrombus from the circulation. The presence of aortic neck thrombus may not necessarily be a contraindication to endovascular repair in select patients. (J Vasc Surg 2001;33:340-4.

Seasonal and Temperature-Associated Increases in Gram-Negative Bacterial Bloodstream Infections among Hospitalized Patients

BACKGROUND: Knowledge of seasonal trends in hospital-associated infection incidence may improve surveillance and help guide the design and evaluation of infection prevention interventions. We estimated seasonal variation in the frequencies of inpatient bloodstream infections (BSIs) caused by common bacterial pathogens and examined associations of monthly BSI frequencies with ambient outdoor temperature, precipitation, and humidity levels. METHODS: A database containing blood cultures from 132 U.S. hospitals collected between January 1999 and September 2006 was assembled. The database included monthly counts of inpatient blood cultures positive for several clinically important Gram-negative bacteria (Acinetobacter spp, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) and Gram-positive bacteria (Enterococcus spp and Staphylococcus aureus). Monthly mean temperature, total precipitation, and mean relative humidity in the postal ZIP codes of participating hospitals were obtained from national meteorological databases. RESULTS: A total of 211,697 inpatient BSIs were reported during 9,423 hospital-months. Adjusting for long-term trends, BSIs caused by each gram-negative organism examined were more frequent in summer months compared with winter months, with increases ranging from 12.2% for E. coli (95% CI 9.2-15.4) to 51.8% for Acinetobacter (95% CI 41.1-63.2). Summer season was associated with 8.7% fewer Enterococcus BSIs (95% CI 11.0-5.8) and no significant change in S. aureus BSI frequency relative to winter. Independent of season, monthly humidity, monthly precipitation, and long-term trends, each 5.6°C (10°F) rise in mean monthly temperature corresponded to increases in gram-negative bacterial BSI frequencies ranging between 3.5% for E. coli (95% CI 2.1-4.9) to 10.8% for Acinetobacter (95% CI 6.9-14.7). The same rise in mean monthly temperature corresponded to an increase of 2.2% in S. aureus BSI frequency (95% CI 1.3-3.2) but no significant change in Enterococcus BSI frequency. CONCLUSIONS: Summer season and higher mean monthly outdoor temperature are associated with substantially increased frequency of BSIs, particularly among clinically important gram-negative bacteria

Cas3 Protein—A Review of a Multi-Tasking Machine

Cas3 has essential functions in CRISPR immunity but its other activities and roles, in vitro and in cells, are less widely known. We offer a concise review of the latest understanding and questions arising from studies of Cas3 mechanism during CRISPR immunity, and highlight recent attempts at using Cas3 for genetic editing. We then spotlight involvement of Cas3 in other aspects of cell biology, for which understanding is lacking—these focus on CRISPR systems as regulators of cellular processes in addition to defense against mobile genetic element

Solar-Powered Coin-Operated Mobile Charging Station for Sustainable Energy Access and Resilience

This study centers on the creation of a cutting-edge coin-operated mobile gadget charging station, harnessing the inexhaustible power of solar energy via an integrated storage battery. The primary objective is to champion solar energy as a sustainable off-grid power source with boundless growth potential. Moreover, this innovative solution extends its utility to the commercial realm, where users can access it for a nominal fee, ensuring their mobile gadgets remain charged for specified periods. In addition to its commercial viability, this charging station also serves as a crucial lifeline during unforeseen calamities and prolonged power outages, offering an essential emergency charging station. Its self-sufficient design allows it to continually charge mobile devices in the presence of sunlight. Whether it's day or night, the coin-operated mobile gadget charging station stands ready to power up small electronics and mobile devices, ensuring uninterrupted connectivity

Parametric studies of penetration events : a design and analysis of experiments approach.

A numerical screening study of the interaction between a penetrator and a geological target with a preformed hole has been carried out to identify the main parameters affecting the penetration event. The planning of the numerical experiment was based on the orthogonal array OA(18,7,3,2), which allows 18 simulation runs with 7 parameters at 3 levels each. The strength of 2 of the array allows also for two-factor interaction studies. The seven parameters chosen for this study are: penetrator offset, hole diameter, hole taper, vertical and horizontal velocity of the penetrator, angle of attack of the penetrator and target material. The analysis of the simulation results has been based on main effects plots and analysis of variance (ANOVA), and it has been performed using three metrics: the maximum values of the penetration depth, penetrator deceleration and plastic strain in the penetrator case. This screening study shows that target material has a major influence on penetration depth and penetrator deceleration, while penetrator offset has the strongest effect on the maximum plastic strain

Predicting iliac limb occlusions after bifurcated aortic stent grafting: Anatomic and device-related causes

AbstractObjective: Graft limb occlusion may complicate endovascular abdominal aortic aneurysm repair. The precise etiologic factors that contribute to the development of these graft limb thromboses have not been defined. We evaluated our experience with bifurcated aortic endografts to determine factors that may predict subsequent limb thrombosis. The management of the thrombosed limbs and the results after treatment were also investigated. Methods: During a 4-year period, 351 patients with aortic aneurysms underwent treatment with bifurcated endografts (702 graft limbs at risk). These 351 bifurcated devices included AneuRx (Medtronic, Minneapolis, Minn; n = 35), Ancure (Guidant, Menlo Park, Calif; n = 8), Gore (W.L. Gore & Associates, Sunnyvale, Calif; n = 25), Talent (World Medical, Sunrise, Fla; n = 255), Teramed (Teramed, Minneapolis, Minn; n = 10), and Vanguard (Boston Scientific Vascular, Natick, Mass; n = 18). Details regarding the type of device, mechanism of deployment, and aortoiliac artery anatomy were collected prospectively and analyzed. Graft limbs were analyzed for diameter, use of additional endograft iliac extensions, deployment in the external iliac artery, and endograft to vessel oversizing. Follow-up included physical examination, duplex ultrasonography, and spiral computed tomographic scans at 1 month, 6 months, and 12 months and annually thereafter. The follow-up period ranged from 2 to 54 months, with a mean follow-up period of 20 months. Results: Twenty-six of 702 limbs (3.7%) had an occlusion develop. The risk of limb thrombosis was associated with a smaller limb diameter. Mean graft limb diameter was 14 mm in the occluded population, and patent limbs had a mean diameter of 16 mm. Thrombosis occurred in 16 of 291 limbs (5.5%) that were 14 mm or less and in 10 of 411 limbs (2.4%) that were greater than 14 mm (P = .03). Extension of a graft to the external iliac artery was performed in 96 of the 702 limbs. Eight of these 96 limbs (8.3%) had thrombosis develop as compared with 18 of 606 (3.0%) that extended to the common iliac artery (P = .01). No significant association was present between limb thrombosis and the contralateral or ipsilateral side of a device, the configuration of the iliac graft limb end (closed web, open web, or bare spring), or the degree of iliac graft limb oversizing. AneuRx, Ancure, Vanguard, and Talent grafts each sustained limb occlusions, with no occlusions seen among the Gore and Teramed devices. No significant increased risk of graft limb thrombosis was observed in unsupported grafts (1/16; 6.3%) versus supported grafts (25/686; 3.6%; P = not significant). Thromboses occurred between 1 day and 23 months after surgery. Thirteen of the 26 thromboses (50%) occurred within 30 days of surgery. Presenting symptoms were mild to moderate claudication in eight patients (30.8%), severe claudication in 16 patient (61.5%), and paresthesia and rest pain in two patients (7.7%). Eighteen of 26 patients (69.2%) eventually needed intervention to reestablish flow to the occluded limb, including thrombolysis and stenting in two patients (7.7%), axillary femoral bypass in one patient (3.8%), femoral-femoral bypass in 13 patients (50.0%), and axillary-bifemoral bypass in two patients (7.7%). All patients with mild to moderate symptoms under observation had improvement in symptoms with no further interventions necessary. All revascularizations were successful in relieving symptoms. Conclusion: Graft limb occlusion is a recognized complication of endovascular treatment of abdominal aortic aneurysms that may be associated with smaller graft limb diameter and extension to the external iliac artery. Occlusions usually necessitate additional intervention for resolution of ischemic symptoms. The use of small diameter grafts should be avoided when possible to reduce the risk of graft limb occlusions. (J Vasc Surg 2002;36:679-84.

Minimax Current Density Coil Design

'Coil design' is an inverse problem in which arrangements of wire are designed to generate a prescribed magnetic field when energized with electric current. The design of gradient and shim coils for magnetic resonance imaging (MRI) are important examples of coil design. The magnetic fields that these coils generate are usually required to be both strong and accurate. Other electromagnetic properties of the coils, such as inductance, may be considered in the design process, which becomes an optimization problem. The maximum current density is additionally optimized in this work and the resultant coils are investigated for performance and practicality. Coils with minimax current density were found to exhibit maximally spread wires and may help disperse localized regions of Joule heating. They also produce the highest possible magnetic field strength per unit current for any given surface and wire size. Three different flavours of boundary element method that employ different basis functions (triangular elements with uniform current, cylindrical elements with sinusoidal current and conic section elements with sinusoidal-uniform current) were used with this approach to illustrate its generality.Comment: 24 pages, 6 figures, 2 tables. To appear in Journal of Physics D: Applied Physic

Outcome of elective endovascular abdominal aortic aneurysm repair in nonagenarians

ObjectiveCompared with open repair of abdominal aortic aneurysms (AAA), endovascular repair (EVAR) is associated with decreased perioperative morbidity and mortality in a standard patient population. This study sought to determine if the advantage of EVAR extends to patients aged ≥90 years.MethodsThis was a retrospective review from a prospectively maintained computerized database. Of the 322 patients aged ≥80 treated with EVAR from January 1997 to November 2007, 24 (1.9%) were aged ≥90. Mean age was 91.5 ± 1.5 years (range, 90-95 years), and 83.3% were men. Mean aneurysm size was 6.8 cm (range, 5.2-8.7 cm).ResultsMean procedural blood loss was 490 mL (range, 100-4150 mL), and 20.8% required an intraoperative transfusion. Mean postoperative length of stay was 6.0 days, (median, 4 days; mode, 1 day; range, 1-42 days), with 33.3% of patients discharged on the first postoperative day. Amongst the 24 patients, there were 6 (25.0%) perioperative major adverse events, and 2 patients died, for a perioperative mortality rate of 8.3%. Mean follow-up was 20.5 months (range, 1-49 months). Overall, three patients (12.5%) required a secondary intervention, comprising thrombectomy, angioplasty, and proximal cuff extension. No patients required conversion to open repair. Two patients (8.3%) died of AAA rupture at 507 and 1254 days. Freedom from all-cause mortality was 83.3% at 1 year and 19.3% at 5 years. Freedom from aneurysm-related mortality was 87.5% at 1 year and 73.2% at 5 years. Endoleak occurred in five patients (20.8%), with three type I and two of indeterminate type; of these, two patients with type I endoleak underwent secondary intervention at 153 and 489 days after EVAR, of which one case was successful.ConclusionOur study supports that EVAR in nonagenarians is associated with acceptable procedural success and perioperative morbidity and mortality. The medium-term results suggest that EVAR may be of limited benefit in very carefully selected patients who are aged ≥90 years