scholarly journals Platypnea-Orthodeoxia Syndrome: Positional Reversal of the Interatrial Pressure Gradient Demonstrated by Atrial Septal Motion

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Farris Serio ◽  
Kerala Serio M
Keyword(s):  
Pressure Gradient ◽  
Septal Motion

Why septal motion is a marker of right ventricular failure in pulmonary arterial hypertension: mechanistic analysis using a computer model

2017 ◽  
Vol 312 (4) ◽  
pp. H691-H700 ◽  
Author(s):  
Georgina Palau-Caballero ◽  
John Walmsley ◽  
Vanessa Van Empel ◽  
Joost Lumens ◽  
Tammo Delhaas
Keyword(s):  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Pressure Gradient ◽  
Right Ventricular ◽  
Left Ventricular ◽  
Contractile Dysfunction ◽  
Ventricular Relaxation ◽  
Pulmonary Arterial ◽  
Rv Function ◽  
Septal Motion

Rapid leftward septal motion (RLSM) during early left ventricular (LV) diastole is observed in patients with pulmonary arterial hypertension (PAH). RLSM exacerbates right ventricular (RV) systolic dysfunction and impairs LV filling. Increased RV wall tension caused by increased RV afterload has been suggested to cause interventricular relaxation dyssynchrony and RLSM in PAH. Simulations using the CircAdapt computational model were used to unravel the mechanism underlying RLSM by mechanistically linking myocardial tissue and pump function. Simulations of healthy circulation and mild, moderate, and severe PAH were performed. We also assessed the effects on RLSM when PAH coexists with RV or LV contractile dysfunction. Our results showed prolonged RV shortening in PAH causing interventricular relaxation dyssynchrony and RLSM. RLSM was observed in both moderate and severe PAH. A negative transseptal pressure gradient only occurred in severe PAH, demonstrating that negative pressure gradient does not entirely explain septal motion abnormalities. PAH coexisting with RV contractile dysfunction exacerbated both interventricular relaxation dyssynchrony and RLSM. LV contractile dysfunction reduced both interventricular relaxation dyssynchrony and RLSM. In conclusion, dyssynchrony in ventricular relaxation causes RLSM in PAH. Onset of RLSM in patients with PAH appears to indicate a worsening in RV function and hence can be used as a sign of RV failure. However, altered RLSM does not necessarily imply an altered RV afterload, but it can also indicate altered interplay of RV and LV contractile function. Reduction of RLSM can result from either improved RV function or a deterioration of LV function. NEW & NOTEWORTHY A novel approach describes the mechanism underlying abnormal septal dynamics in pulmonary arterial hypertension. Change in motion is not uniquely induced by altered right ventricular afterload, but also by altered ventricular relaxation dyssynchrony. Extension or change in motion is a marker reflecting interplay between right and left ventricular contractility.

scholarly journals Transseptal pressure gradient and diastolic ventricular septal motion in patients with mitral stenosis.

Circulation ◽  
1987 ◽  
Vol 76 (5) ◽  
pp. 974-980 ◽  
Author(s):  
C R Thompson ◽  
I Kingma ◽  
R P MacDonald ◽  
I Belenkie ◽  
J V Tyberg ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Mitral Stenosis ◽  
Septal Motion

Correlation of paradoxical atrial septal motion and an interatrial pressure gradient in severe tricuspid regurgitation

1985 ◽  
Vol 55 (11) ◽  
pp. 1431-1433 ◽  
Author(s):  
Robert F. Percy ◽  
Donald A. Conetta ◽  
Edward A. Geiser ◽  
Theodore A. Bass ◽  
C.Richard Conti ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Tricuspid Regurgitation ◽  
Severe Tricuspid Regurgitation ◽  
Septal Motion

Activated Prominences; Mechanisms for Activation and Eruption

1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer
Keyword(s):  
Pressure Gradient ◽  
Density Gradient ◽  
Current Density ◽  
Convective Instability ◽  
Tearing Mode ◽  
Magnetic Shear ◽  
Long Wavelength ◽  
Ideal Mhd ◽  
Gradient Change ◽  
Accelerated Particles

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.

An Attack on the Contamination Problem in the Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 368-368
Author(s):  
J. J. Kelsch ◽  
A. Holtz
Keyword(s):  
Electron Microscope ◽  
Pressure Gradient ◽  
Ionization Potential ◽  
Simple Solution ◽  
Specimen Surface ◽  
Contamination Rate ◽  
Local Pressure ◽  
High Ionization ◽  
Hydrocarbon Molecules ◽  
Contamination Problem

A simple solution to the serious problem of specimen contamination in the electron microscope is presented. This is accomplished by the introduction of clean helium into the vacuum exactly at the specimen position. The local pressure gradient thus established inhibits the migration of hydrocarbon molecules to the specimen surface. The high ionization potential of He permits the use of relatively large volumes of the gas, without interfering with gun stability. The contamination rate is reduced on metal samples by a factor of 10.

Hydration Chamber for Jeolco 200 Kv Microscope

1970 ◽  
Vol 28 ◽  
pp. 542-543
Author(s):  
V. R. Matricardi ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Electron Microscope ◽  
Water Vapor ◽  
Vapor Pressure ◽  
Pressure Gradient ◽  
Room Temperature ◽  
List Type ◽  
Type Number ◽  
Equilibrium Vapor Pressure

In order to observe room temperature hydrated specimens in an electron microscope, the following conditions should be satisfied: The specimen should be surrounded by water vapor as close as possible to the equilibrium vapor pressure corresponding to the temperature of the specimen.The specimen grid should be inserted, focused and photo graphed in the shortest possible time in order to minimize dehydration.The full area of the specimen grid should be visible in order to minimize the number of changes of specimen required.There should be no pressure gradient across the grid so that specimens can be straddled across holes.Leakage of water vapor to the column should be minimized.

Risk Factors for Hepatic Encephalopathy after Transjugular Intrahepatic Portosystemic Shunt in Patients with Hepatocellular Carcinoma and Portal Hypertension

2015 ◽  
Vol 24 (3) ◽  
pp. 301-307 ◽  
Author(s):  
Jiannan Yao ◽  
Li Zuo ◽  
Guangyu An ◽  
Zhendong Yue ◽  
Hongwei Zhao ◽  
...  
Keyword(s):  
Risk Factors ◽  
Hepatocellular Carcinoma ◽  
Portal Hypertension ◽  
Hepatic Encephalopathy ◽  
Pressure Gradient ◽  
Transjugular Intrahepatic Portosystemic Shunt ◽  
Meld Score ◽  
Portosystemic Shunt ◽  
Portal Flow ◽  
Intrahepatic Portosystemic Shunt

Aims: This study aimed at assessing the risk factors for hepatic encephalopathy (HE) after transjugular intrahepatic portosystemic shunt (TIPS) in patients with hepatocellular carcinoma (HCC) and portal hypertension. Method: Consecutive patients (n=279) with primary HCC who underwent TIPS between January 1997 and March 2012 at a single institution were retrospectively reviewed. Patients were followed up for 2 years. Pre-TIPS, peri-TIPS and post-TIPS clinical variables were reviewed using univariate and multivariate analyses to identify risk factors for HE after TIPS. Results: The overall incidence of HE was 41% (114/279). Multivariate analysis showed an increased odds for HE in patients with: >3 treatments with transcatheter arterial chemoembolization (TACE) and/or trans-arterial embolization (TAE) (odds ratio [OR], 4.078; 95% confidence interval [95%CI], 1.748-9.515); hepatopetal portal flow (OR, 2.362; 95%CI, 1.032-5.404); high portosystemic pressure gradient (OR, 1.198; 95%CI, 1.073-1.336) and high pre-TIPS MELD score (OR, 1.693; 95%CI, 1.390-2.062). Odds for HE were increased 1.693 fold for each 1-point increase in the MELD score, and 1.198 fold for each 1-mmHg decrease in the post-TIPS portosystemic pressure gradient. Conclusion: The identification of clinical variables associated with increased odds of HE may be useful for the selection of appropriate candidates for TIPS. Results suggest that an inappropriate decrease in the portosystemic pressure gradient might be associated with HE after TIPS. In addition, >3 treatments with TACE/TAE, hepatopetal portal flow, and high MELD score were also associated with increased odds of HE after TIPS. Key words:  –  –  – .

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