Shocks and Post-shock Plasma Processes

2020 ◽  
pp. 55-85
Author(s):  
Jacco Vink
Keyword(s):  
Post Shock

scholarly journals Constitutively Active Acetylcholine-Dependent Potassium Current Increases Atrial Defibrillation Threshold by Favoring Post-Shock Re-Initiation

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Brian O. Bingen ◽  
Saïd F. A. Askar ◽  
Zeinab Neshati ◽  
Iolanda Feola ◽  
Alexander V. Panfilov ◽  
...  
Keyword(s):  
Potassium Current ◽  
Defibrillation Threshold ◽  
Post Shock ◽  
Atrial Defibrillation ◽  
Constitutively Active

Abstract 2140: Infrequent Need for Pacing Following Implantable Cardioverter-Defibrillator Shocks: Analysis of the Sudden Cardiac Death in Heart Failure Trial

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Jordan M Prutkin ◽  
Jeanne E Poole ◽  
George Johnson ◽  
Jill Anderson ◽  
Daniel B Mark ◽  
...  
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Sudden Cardiac Death ◽  
Cardiac Death ◽  
Nyha Class ◽  
Prior History ◽  
Baseline Heart Rate ◽  
Implantable Cardioverter Defibrillators ◽  
Heart Failure Trial ◽  
Post Shock

Background: Implantable cardioverter-defibrillators (ICD) are routinely programmed to pace after a shock to prevent possible asystole. In those with no prior history of bradycardia, there is little data regarding the prevalence and characteristics of those who use post-shock pacing (PSP). Methods: We analyzed the occurrence of pacing within the first nine beats after the first successful ICD shock for ventricular tachycardia (VT) or ventricular fibrillation (VF) in the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT). All ICDs were single lead with the first PSP delivered at 1400msec and all subsequent stimuli delivered at 1200msec. We excluded patients with pacing during pre-shock rhythms and those who had pacing rates different than the protocol default rate of 50bpm (1200 msec). Results: There were 2521 patients enrolled in SCD-HeFT, of which 811 received an ICD. A total of 153 shock events were examined; 36 (23.5%) had at least one of the first nine beats paced post-shock, though only 4 (2.5%) had greater than 4 out of the 9 beats paced. No subjects needed pacing for all nine beats and only 8 (5.2%) paced for greater than 5 seconds. There were no differences in age, gender, etiology of cardiomyopathy, or NYHA class between those with PSP or not. The prevailing heart rate pre-shock was predictive of PSP; the mean cycle length of the baseline rhythm pre-shock was longer (slower rate) for those who used PSP (735 ± 228msec vs. 624 ± 158msec, P=0.001). More often, VF (vs. VT) was the rhythm shocked in those using PSP (P=0.015). A trend also was seen toward increased frequency of PSP in those receiving 30J shocks (16 of 49) versus ≤20J shocks (20 of 104, P=0.068). Conclusion: Patients infrequently require multiple paced beats post-shock for VT or VF. Patients using PSP have a slower baseline heart rate and are more likely to have VF as the shocked rhythm. While 1 or 2 paced beats out of the first nine occurred occasionally, these patients also had rapid return of their native rhythm for which the hemodynamic contribution of 1 or 2 paced beats is unclear. These data suggest that for most patients receiving a primary prevention ICD programmed for shock-only therapy, the need for PSP is limited. PSP use may reflect convention and the assumption that minor post-shock pauses are detrimental.

Modeling of Hydrogen-Air Detonations in the TONUS CFD Code and Its Application to the FLAME F-19 Test

2008 ◽  
Author(s):  
Eveliina Takasuo
Keyword(s):  
Cfd Simulation ◽  
Hydrogen Combustion ◽  
Severe Accident ◽  
Parameter Study ◽  
Model Parameters ◽  
Gas Detonation ◽  
Global Rate ◽  
Detonation Structure ◽  
Mesh Resolution ◽  
Post Shock

In severe accident management, the ability to predict pressure and thermal loads resulting from hydrogen combustion is important since they may threaten containment integrity. In computational modeling, different combustion regimes have to be accounted for and state-of-the-art techniques developed for reliable analysis. In the present study, the focus is on computational fluid dynamics code validation for reactive flows in the detonation regime. The FLAME hydrogen combustion test F-19 performed at the Sandia National Laboratories has been simulated by using the gas detonation model implemented in the TONUS CFD code which is developed by CEA and IRSN (France). In this model the reactive Euler equations are solved and the reaction rate is obtained by the Arrhenius global rate equation. Several simulations were run in order to examine the effect of modifying the parameters of the chemistry model. A mesh convergence study was performed for the purpose of finding out the necessary mesh resolution which could capture the detonation propagation with adequate accuracy. In addition, Chapman-Jouguet post-shock equilibrium conditions and the ZND detonation structure for the present gas mixture were examined by chemical kinetics calculations. The CFD simulation results were compared to the test results and the Chapman-Jouguet post-shock conditions. It was observed that the computational results differ from the C-J results with the C-J velocity being slightly exceeded. The model parameter study showed that it is not possible to significantly affect the flame propagation by adjusting the model parameters.

HYPEROSMOLARITY ABROGATES NEUTROPHIL PRIMING BY POST-SHOCK MESENTERIC LYMPH

Shock ◽  
2001 ◽  
Vol 15 (Supplement) ◽  
pp. 6
Author(s):  
R J Gonzalez ◽  
E E Moore ◽  
D J Ciesla ◽  
W L Biffl ◽  
C C Silliman
Keyword(s):  
Mesenteric Lymph ◽  
Post Shock ◽  
Neutrophil Priming

scholarly journals Shocked Molecular Hydrogen from Star Forming Regions

1987 ◽  
Vol 115 ◽  
pp. 181-181 ◽  
Author(s):  
Adair P. Lane ◽  
John Bally
Keyword(s):  
Shock Waves ◽  
High Velocity ◽  
Molecular Hydrogen ◽  
Near Infrared ◽  
Young Stars ◽  
Emission Lines ◽  
Molecular Gas ◽  
Star Forming ◽  
Star Forming Regions ◽  
Post Shock

Near infrared (2 micron) emission lines from molecular hydrogen provide a powerful probe of the morphology and energetics of outflows associated with stellar birth. The H2 emission regions trace the location of shock waves formed when the high velocity outflow from young stars encounters dense quiescent gas. Since H2 is the dominant coolant of the hot post-shock molecular gas, the H2 lines provide a measure of the fraction of the total mechanical luminosity radiated away from the cloud.

scholarly journals Are cosmological gas accretion streams multiphase and turbulent?

2018 ◽  
Vol 610 ◽  
pp. A75 ◽  
Author(s):  
Nicolas Cornuault ◽  
Matthew D. Lehnert ◽  
François Boulanger ◽  
Pierre Guillard
Keyword(s):  
Galaxy Formation ◽  
Direct Interaction ◽  
Mass Range ◽  
Initial Kinetic Energy ◽  
Two Phase ◽  
Dynamical Time ◽  
Order Of Magnitude ◽  
Post Shock ◽  
Gas Accretion ◽  
Halo Gas

Simulations of cosmological filamentary accretion reveal flows (“streams”) of warm gas, T ~ 104 K, which bring gas into galaxies efficiently. We present a phenomenological scenario in which gas in such flows, if it is shocked as it enters the halo as we assume and depending on the post-shock temperature, stream radius, its relative overdensity, and other factors, becomes biphasic and turbulent. We consider a collimated stream of warm gas that flows into a halo from an overdense filament of the cosmic web. The post-shock streaming gas expands because it has a higher pressure than the ambient halo gas and fragments as it cools. The fragmented stream forms a two phase medium: a warm cloudy phase embedded in hot post-shock gas. We argue that the hot phase sustains the accretion shock. During fragmentation, a fraction of the initial kinetic energy of the infalling gas is converted into turbulence among and within the warm clouds. The thermodynamic evolution of the post-shock gas is largely determined by the relative timescales of several processes. These competing timescales characterize the cooling, expansion of the post-shock gas, amount of turbulence in the clouds, and dynamical time of the halo. We expect the gas to become multiphase when the gas cooling and dynamical times are of the same order of magnitude. In this framework, we show that this mainly occurs in the mass range, Mhalo ~ 1011 to 1013 M⊙, where the bulk of stars have formed in galaxies. Because of the expansion of the stream and turbulence, gas accreting along cosmic web filaments may eventually lose coherence and mix with the ambient halo gas. Through both the phase separation and “disruption” of the stream, the accretion efficiency onto a galaxy in a halo dynamical time is lowered. Decollimating flows make the direct interaction between galaxy feedback and accretion streams more likely, thereby further reducing the overall accretion efficiency. As we discuss in this work, moderating the gas accretion efficiency through these mechanisms may help to alleviate a number of significant challenges in theoretical galaxy formation.

Sign in / Sign up

Export Citation Format

Share Document