Competing Approaches to Defining Right Ventricular Motion Directions in Three Dimensions: A Pressing Need for Standardization?

2020 ◽  
Author(s):  
Márton Tokodi ◽  
Bálint Károly Lakatos ◽  
Zoltán Tősér ◽  
Béla Merkely ◽  
Masaaki Takeuchi ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Three Dimensions ◽  
Ventricular Motion

scholarly journals Basis for the Induction of Tissue-Level Phase-2 Reentry as a Repolarization Disorder in the Brugada Syndrome

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Alfonso Bueno-Orovio ◽  
Elizabeth M. Cherry ◽  
Steven J. Evans ◽  
Flavio H. Fenton
Keyword(s):  
Action Potential ◽  
Right Ventricular ◽  
Brugada Syndrome ◽  
Action Potentials ◽  
Human Action ◽  
Three Dimensions ◽  
Phase 2 ◽  
Three Dimensional Model ◽  
Right Ventricular Free Wall ◽  
The Right

Aims. Human action potentials in the Brugada syndrome have been characterized by delayed or even complete loss of dome formation, especially in the right ventricular epicardial layers. Such a repolarization pattern is believed to trigger phase-2 reentry (P2R); however, little is known about the conditions necessary for its initiation. This study aims to determine the specific mechanisms that facilitate P2R induction in Brugada-affected cardiac tissue in humans.Methods. Ionic models for Brugada syndrome in human epicardial cells were developed and used to study the induction of P2R in cables, sheets, and a three-dimensional model of the right ventricular free wall.Results. In one-dimensional cables, P2R can be induced by adjoining lost-dome and delayed-dome regions, as mediated by tissue excitability and transmembrane voltage profiles, and reduced coupling facilitates its induction. In two and three dimensions, sustained reentry can arise when three regions (delayed-dome, lost-dome, and normal epicardium) are present.Conclusions. Not only does P2R induction by Brugada syndrome require regions of action potential with delayed-dome and lost-dome, but in order to generate a sustained reentry from a triggered waveback multiple factors are necessary, including heterogeneity in action potential distribution, tissue coupling, direction of stimulation, the shape of the late plateau, the duration of lost-dome action potentials, and recovery of tissue excitability, which is predominantly modulated by tissue coupling.

Assessment of right ventricular motion with magnetic resonance tissue tagging and slice following

1995 ◽  
Vol 2 (2) ◽  
pp. S42-S42
Author(s):  
E NAGEL ◽  
M STUBER ◽  
S FISCHER ◽  
P BOESIGER ◽  
R SIMON ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Right Ventricular ◽  
Tissue Tagging ◽  
Ventricular Motion

scholarly journals Machine Learning of Three-dimensional Right Ventricular Motion Enables Outcome Prediction in Pulmonary Hypertension: A Cardiac MR Imaging Study

Radiology ◽  
2017 ◽  
Vol 283 (2) ◽  
pp. 381-390 ◽  
Author(s):  
Timothy J. W. Dawes ◽  
Antonio de Marvao ◽  
Wenzhe Shi ◽  
Tristan Fletcher ◽  
Geoffrey M. J. Watson ◽  
...  
Keyword(s):  
Machine Learning ◽  
Pulmonary Hypertension ◽  
Mr Imaging ◽  
Right Ventricular ◽  
Outcome Prediction ◽  
Three Dimensional ◽  
Imaging Study ◽  
Cardiac Mr ◽  
Ventricular Motion

scholarly journals Right Ventricular Function and Its Coupling With Pulmonary Circulation in Precapillary Pulmonary Hypertension: A Three-Dimensional Echocardiographic Study

2021 ◽  
Vol 8 ◽  
Author(s):  
Yidan Li ◽  
Dichen Guo ◽  
Juanni Gong ◽  
Jianfeng Wang ◽  
Qiang Huang ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Right Ventricular ◽  
Clinical Outcomes ◽  
Predictive Value ◽  
Arterial Compliance ◽  
Systolic Pressure ◽  
Functional Class ◽  
Three Dimensions ◽  
World Health ◽  
Pulmonary Arterial

Objective: To assess right ventricular (RV) function and RV-pulmonary arterial (PA) coupling by three-dimensions echocardiography and investigate the ability of RV-PA coupling to predict adverse clinical outcomes in patients with precapillary pulmonary hypertension (PH).Methods: We retrospectively collected a longitudinal cohort of 203 consecutive precapillary PH patients. RV volume, RV ejection fraction (RVEF), and RV longitudinal strain (RVLS) were quantitatively determined offline by 3D echocardiography. RV-PA coupling parameters including the RVEF/PA systolic pressure (PASP) ratio, pulmonary arterial compliance (PAC), and total pulmonary resistance (TPR) were recorded.Results: Over a median follow-up period of 20.9 months (interquartile range, 0.1–67.4 months), 87 (42.9%) of 203 patients experienced adverse clinical outcomes. With increasing World Health Organization functional class (WHO-FC), significant trends were observed in increasing RV volume, decreasing RVEF, and worsening RVLS. RV arterial coupling (RVAC) and PAC were lower and TPR was higher for WHO-FC III+IV than WHO-FC I or II. The RVEF/PASP ratio showed a significant correlation with RVLS. RVAC had a stronger correlation with the RVEF/PASP ratio than other indices. Multivariate Cox proportional-hazard analysis identified a lower 3D RVEF and worse RVLS as strong predictors of adverse clinical events. RVAC, TPR, and PAC had varying degrees of predictive value, with optimal cutoff values of 0.74, 11.64, and 1.18, respectively.Conclusions: Precapillary-PH with RV-PA uncoupling as expressed by a RVEF/PASP ratio <0.44 was associated with adverse clinical outcomes. PAC decreased and TPR increased with increasing WHO-FC, with TPR showing better independent predictive value.

scholarly journals Quantifying right ventricular motion and strain using 3D cine DENSE MRI

2011 ◽  
Vol 13 (S1) ◽  
Author(s):  
Daniel A Auger ◽  
Xiaodong Zhong ◽  
Ernesta M Meintjes ◽  
Frederick H Epstein ◽  
Bruce S Spottiswoode
Keyword(s):  
Right Ventricular ◽  
Ventricular Motion ◽  
Cine Dense

High-resolution scanning electron microscopy (HRSEM) of mitochondria from various rat tissues

1988 ◽  
Vol 46 ◽  
pp. 14-15
Author(s):  
P.J. Lea ◽  
M.J. Hollenberg
Keyword(s):  
Electron Microscopy ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Rat Hepatocytes ◽  
Three Dimensions ◽  
Objective Lens ◽  
Rat Tissues ◽  
Thin Sections ◽  
Reconstruction Methods ◽  
Scanning Electron

Our current understanding of mitochondrial ultrastructure has been derived primarily from thin sections using transmission electron microscopy (TEM). This information has been extrapolated into three dimensions by artist's impressions (1) or serial sectioning techniques in combination with computer processing (2). The resolution of serial reconstruction methods is limited by section thickness whereas artist's impressions have obvious disadvantages.In contrast, the new techniques of HRSEM used in this study (3) offer the opportunity to view simultaneously both the internal and external structure of mitochondria directly in three dimensions and in detail.The tridimensional ultrastructure of mitochondria from rat hepatocytes, retinal (retinal pigment epithelium), renal (proximal convoluted tubule) and adrenal cortex cells were studied by HRSEM. The specimens were prepared by aldehyde-osmium fixation in combination with freeze cleavage followed by partial extraction of cytosol with a weak solution of osmium tetroxide (4). The specimens were examined with a Hitachi S-570 scanning electron microscope, resolution better than 30 nm, where the secondary electron detector is located in the column directly above the specimen inserted within the objective lens.

Inelastic Electron Scattering from Valence Electrons in Aluminum

1976 ◽  
Vol 34 ◽  
pp. 462-463
Author(s):  
P. E. Batson ◽  
C. H. Chen ◽  
J. Silcox
Keyword(s):  
Electron Scattering ◽  
Single Scattering ◽  
Three Dimensions ◽  
Inelastic Electron ◽  
Weak Beam ◽  
Scattering Spectrum ◽  
Valence Electrons ◽  
Diffraction Patterns ◽  
Electronic Scattering

We wish to report in this paper measurements of the inelastic scattering component due to the collective excitations (plasmons) and single particlehole excitations of the valence electrons in Al. Such scattering contributes to the diffuse electronic scattering seen in electron diffraction patterns and has recently been considered of significance in weak-beam images (see Gai and Howie) . A major problem in the determination of such scattering is the proper correction for multiple scattering. We outline here a procedure which we believe suitably deals with such problems and report the observed single scattering spectrum.In principle, one can use the procedure of Misell and Jones—suitably generalized to three dimensions (qx, qy and #x2206;E)--to derive single scattering profiles. However, such a computation becomes prohibitively large if applied in a brute force fashion since the quasi-elastic scattering (and associated multiple electronic scattering) extends to much larger angles than the multiple electronic scattering on its own.

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