Cardioembolic Stroke Kamel, Hooman; Healey, Jeff S
Circulation research,
2017-February-3, 2017-Feb-03, 2017-02-03, 20170203, Letnik:
120, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Cardiac embolism accounts for an increasing proportion of ischemic strokes and might multiply several-fold during the next decades. However, research points to several potential strategies to stem ...this expected rise in cardioembolic stroke. First, although one-third of strokes are of unclear cause, it is increasingly accepted that many of these cryptogenic strokes arise from a distant embolism rather than in situ cerebrovascular disease, leading to the recent formulation of embolic stroke of undetermined source as a distinct target for investigation. Second, recent clinical trials have indicated that embolic stroke of undetermined source may often stem from subclinical atrial fibrillation, which can be diagnosed with prolonged heart rhythm monitoring. Third, emerging evidence indicates that a thrombogenic atrial substrate can lead to atrial thromboembolism even in the absence of atrial fibrillation. Such an atrial cardiomyopathy may explain many cases of embolic stroke of undetermined source, and oral anticoagulant drugs may prove to reduce stroke risk from atrial cardiomyopathy given its parallels to atrial fibrillation. Non–vitamin K antagonist oral anticoagulant drugs have recently expanded therapeutic options for preventing cardioembolic stroke and are currently being tested for stroke prevention in patients with embolic stroke of undetermined source, including specifically those with atrial cardiomyopathy. Fourth, increasing appreciation of thrombogenic atrial substrate and the common coexistence of cardiac and extracardiac stroke risk factors suggest benefits from global vascular risk factor management in addition to anticoagulation. Finally, improved imaging of ventricular thrombus plus the availability of non–vitamin K antagonist oral anticoagulant drugs may lead to better prevention of stroke from acute myocardial infarction and heart failure.
Observational studies suggest that we often fail to detect paroxysmal atrial fibrillation as the cause of ischemic stroke.
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However, owing to the limitations of existing studies, guidelines have yet ...to endorse specific strategies for detecting atrial fibrillation in patients with a new stroke.
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The results of two studies published in this issue of the
Journal
indicate that prolonged monitoring of heart rhythm should now become part of the standard care of patients with cryptogenic stroke.
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This finding represents an important advance, because typical evaluations fail to determine the cause of one third of ischemic strokes. Cryptogenic strokes often . . .
Using administrative claims data, the authors found significantly increased risks for primary thrombotic events beyond the 6-week postpartum period, when the risk is well recognized to be high. ...However, absolute increases in risk from 7 to 12 weeks after delivery were small.
Pregnancy significantly increases the risk of thrombosis. This heightened thrombotic risk rises further during the postpartum period, which is conventionally defined as the 6 weeks after delivery.
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As compared with the nonpregnant state, the 6-week postpartum period is associated with increases by a factor of 3 to 9 in the risk of stroke, by a factor of 3 to 6 in the risk of myocardial infarction, and by a factor of 9 to 22 in the risk of venous thromboembolism.
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It is unknown whether these risks remain increased after the conventionally defined 6-week postpartum period. Guidelines for the treatment . . .
This paper presents an experimental investigation of the solid–liquid phase change process of three natural paraffin waxes, which show slightly different melting temperature: 53 °C, 57 °C, and 59 °C, ...at three heat fluxes: 6.25, 12.5, and 18.75 kW m−2. Furthermore, the use of copper foams to improve the phase change process is experimentally studied by employing three different samples with 5, 10, and 40 PPI and constant porosity equal to 0.95. The experimental results clearly show that the presence of the foam matrix improves the heat transfer capabilities of the passive system allowing for lower surface temperature compared to no-foam case, at the same imposed heat flux. A direct video visualization of the process also permitted to show the effects of the porous medium on melting and solidification processes.
•The phase change process of three paraffin waxes is experimentally studied.•Three copper foams are used to enhance the phase change process.•The visualization of the phase change process with and without foam is presented.•The copper foams strongly enhance the PCM heat transfer performance.•The foams mitigate the paraffin volume change issues in the melt.
Abstract
BACKGROUND
Chronic subdural hematoma (SDH) is a particularly challenging pathology due to high recurrence rates (2%-37%) and complex medical comorbidities that tend to afflict the patient ...population. Recently, there have been several case series published describing the use of middle meningeal artery (MMA) embolization as an alternative to surgery for treatment of new or recurrent chronic SDH.
OBJECTIVE
To describe our first 60 cases of MMA embolization for chronic SDH.
METHODS
MMA embolization was performed using angiography, selective microcatheterization of the MMA, and infusion of polyvinyl alcohol particles. Outcomes were assessed clinically and with interval imaging studies at 1 d, 2 wk, and 6 wk postprocedure, and additional intervals as indicated.
RESULTS
MMA embolization was performed successfully on 60 total SDHs in 49 patients. This includes upfront treatment for new (not previously treated) SDH in 42, for recurrence in 8, and prophylaxis (soon after surgical evacuation) in 10. There were 3 mortalities (unrelated to the procedure), and no procedural complications. Of the 50 nonprophylactic cases, there were 4 (8.9%) cases of recurrence requiring surgical evacuation, and 31 (68.9%) that had resolution or reduction in size >50% of SDH at longest follow-up. Overall, 41 (91.1%) were stable or decreased in size and able to avoid surgery.
CONCLUSION
MMA embolization may represent a minimally-invasive alternative to surgery for new or recurrent chronic SDH, or as prophylaxis to reduce the risk of recurrence after surgery. Given our encouraging results with a 91% long-term success rate, a large scale clinical trial is warranted.
In this research, pore scale simulation of natural convection in a differentially heated enclosure filled with a conducting bidisperse porous medium is investigated using the thermal lattice ...Boltzmann method. For the first time, the effect of connection of the bidisperse porous medium to the enclosure walls is studied by considering the attached geometry in addition to the detached one. Effect of most relevant parameters on the streamlines and isotherms as well as hot wall average Nusselt number is studied for two of the bidisperse porous medium configurations. It is observed that effect of geometrical and thermo-physical parameters of the bidisperse porous medium on the heat transfer characteristics is more complicated for the attached configuration. To assess the validity of the local thermal equilibrium condition in the micro-porous media, the pore scale results are used to compute the percentage of the local thermal non-equilibrium for two of the bidisperse porous medium configurations. It is concluded that for the detached configuration, the local thermal equilibrium condition is confirmed in the entire micro-porous media for the ranges of the parameters studied here. However, for the attached geometry, it is shown that departure from the local thermal equilibrium condition is observed for the higher values of the Rayleigh number, micro-porous porosity, solid–fluid thermal conductivity ratio, and the smaller values of the macro-pores volume fraction.
Abstract Background Although ventriculoperitoneal shunt (VPS) surgery is the most frequent surgical treatment for patients with hydrocephalus, modern rates of complications in adults are uncertain. ...Methods We performed a retrospective cohort study of adult patients hospitalized at the time of their first recorded procedure code for VPS surgery between 2005 and 2012 at nonfederal acute care hospitals in California, Florida, and New York. We excluded patients who during the index hospitalization for VPS surgery had concomitant codes for VPS revision, CNS infection, or died during the index hospitalization. Patients were followed for the primary outcome of a VPS complication, defined as the composite of CNS infection or VPS revision. Survival statistics were used to calculate the cumulative rate and incidence rate of VPS complications. Results 17,035 patients underwent VPS surgery. During a mean follow-up of 3.9 (±1.8) years, at least one VPS complication occurred in 23.8% (95% CI, 22.9-24.7%) of patients. The cumulative rate of CNS infection was 6.1% (95% CI, 5.7-6.5%) and of VPS revision 22.0% (95% CI, 21.1-22.9%). The majority of complications occurred within the first year of hospitalization for VPS surgery. Complication rates were 21.3 (95% CI, 20.6-22.1) complications per 100 patients per year in the first year after VPS surgery, 5.7 (95% CI, 5.3-6.1) in the second year after VPS surgery, and 2.5 (95% CI, 2.1-3.0) in the fifth year after VPS surgery. Conclusions Complications are not infrequent following VPS surgery; however, the majority of complications appear to be clustered in the first year following VPS insertion.
Summary
This paper proposes the use of a hybrid 5 MW power generation system combining concentrated solar thermal and solar photovoltaic technology where the efficiency of the power block is ...increased by taking advantage of hot water from a low‐temperature geothermal source. Aiming at a case study for Winton in Queensland the pertinent meteorological data are used for our simulations. In addition, the paper analyzes the feasibility of including a thermal desalination technology that uses the waste heat from the power block for producing clean water from wastewater. Our design replaces the traditional dry cooling system with a water‐cooled heat exchanger to remove the waste heat from the power block. Finally, this work explores the ratio of concentrated solar thermal and photovoltaic electricity production that optimizes the levelized cost of electricity and water production. the results indicate that the incorporation of the desalination system does not produce a significant increase in this value, and the optimal ratio of electricity production is obtained when the photovoltaic system contributes to 27.5% of the total electricity generation. Our water production cost can be as low as 40 ₵/m3 while for the combined system our minimum levelized cost of electricity figures out at 12.4 ₵/kWh to generate the base load with thermal storage.
IMPORTANCE: Clinically apparent atrial fibrillation increases the risk of ischemic stroke. In contrast, perioperative atrial fibrillation may be viewed as a transient response to physiological ...stress, and the long-term risk of stroke after perioperative atrial fibrillation is unclear. OBJECTIVE: To examine the association between perioperative atrial fibrillation and the long-term risk of stroke. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort study using administrative claims data on patients hospitalized for surgery (as defined by surgical diagnosis related group codes), and discharged alive and free of documented cerebrovascular disease or preexisting atrial fibrillation from nonfederal California acute care hospitals between 2007 and 2011. Patients undergoing cardiac vs other types of surgery were analyzed separately. MAIN OUTCOMES AND MEASURES: Previously validated diagnosis codes were used to identify ischemic strokes after discharge from the index hospitalization for surgery. The primary predictor variable was atrial fibrillation newly diagnosed during the index hospitalization, as defined by previously validated present-on-admission codes. Patients were censored at postdischarge emergency department encounters or hospitalizations with a recorded diagnosis of atrial fibrillation. RESULTS: Of 1 729 360 eligible patients, 24 711 (1.43%; 95% CI, 1.41%-1.45%) had new-onset perioperative atrial fibrillation during the index hospitalization and 13 952 (0.81%; 95% CI, 0.79%-0.82%) experienced a stroke after discharge. At 1 year after hospitalization for cardiac surgery, cumulative rates of stroke were 0.99% (95% CI, 0.81%-1.20%) in those with perioperative atrial fibrillation and 0.83% (95% CI, 0.76%-0.91%) in those without atrial fibrillation. At 1 year after noncardiac surgery, cumulative rates of stroke were 1.47% (95% CI, 1.24%-1.75%) in those with perioperative atrial fibrillation and 0.36% (95% CI, 0.35%-0.37%) in those without atrial fibrillation. In a Cox proportional hazards analysis accounting for potential confounders, perioperative atrial fibrillation was associated with subsequent stroke both after cardiac surgery (hazard ratio, 1.3; 95% CI, 1.1-1.6) and noncardiac surgery (hazard ratio, 2.0; 95% CI, 1.7-2.3). The association was significantly stronger for perioperative atrial fibrillation after noncardiac vs cardiac surgery (P < .001 for interaction). CONCLUSIONS AND RELEVANCE: Among patients hospitalized for surgery, perioperative atrial fibrillation was associated with an increased long-term risk of ischemic stroke, especially following noncardiac surgery.
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