scholarly journals Filament Dynamics during Simulated Ventricular Fibrillation in a High-Resolution Rabbit Heart

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Pras Pathmanathan ◽  
Richard A. Gray
Keyword(s):  
High Resolution ◽  
Ventricular Fibrillation ◽  
Electrical Activity ◽  
Three Dimensional ◽  
Coronary Vessels ◽  
Rabbit Heart ◽  
Filament Dynamics ◽  
Surface Patterns ◽  
Time Specific ◽  
Whole Heart

The mechanisms underlying ventricular fibrillation (VF) are not well understood. The electrical activity on the heart surface during VF has been recorded extensively in the experimental setting and in some cases clinically; however, correspondingtransmuralactivation patterns are prohibitively difficult to measure. In this paper, we use a high-resolution biventricular heart model to study three-dimensional electrical activity during fibrillation, focusing on the driving sources of VF: “filaments,” the organising centres of unstable reentrant scroll waves. We show, for the first time, specific 3D filamentdynamicsduring simulated VF in a whole heart geometry that includes fine-scale anatomical structures. Our results suggest that transmural activity is much more complex than what would be expected from surface observations alone. We present examples of complex intramural activity, including filament breakup and reattachment, anchoring to the thin right ventricular apex; rapid transitions among various filament shapes; and filament lengths much greater than wall thickness. We also present evidence for anatomy playing a major role in VF development and coronary vessels and trabeculae influencing filament dynamics. Overall, our results indicate that intramural activity during simulated VF is extraordinarily complex and suggest that further investigation of 3D filaments is necessary to fully comprehend recorded surface patterns.

scholarly journals Mapping cardiac surface mechanics with structured light imaging

2012 ◽  
Vol 303 (6) ◽  
pp. H712-H720 ◽  
Author(s):  
Jacob I. Laughner ◽  
Song Zhang ◽  
Hao Li ◽  
Connie C. Shao ◽  
Igor R. Efimov
Keyword(s):  
Motion Tracking ◽  
Imaging System ◽  
Normal Sinus Rhythm ◽  
Structured Light ◽  
Three Dimensional ◽  
Cardiac Mechanics ◽  
Rabbit Heart ◽  
Surface Registration ◽  
Whole Heart ◽  
Surface Mechanics

Cardiovascular disease often manifests as a combination of pathological electrical and structural heart remodeling. The relationship between mechanics and electrophysiology is crucial to our understanding of mechanisms of cardiac arrhythmias and the treatment of cardiac disease. While several technologies exist for describing whole heart electrophysiology, studies of cardiac mechanics are often limited to rhythmic patterns or small sections of tissue. Here, we present a comprehensive system based on ultrafast three-dimensional (3-D) structured light imaging to map surface dynamics of whole heart cardiac motion. Additionally, we introduce a novel nonrigid motion-tracking algorithm based on an isometry-maximizing optimization framework that forms correspondences between consecutive 3-D frames without the use of any fiducial markers. By combining our 3-D imaging system with nonrigid surface registration, we are able to measure cardiac surface mechanics at unprecedented spatial and temporal resolution. In conclusion, we demonstrate accurate cardiac deformation at over 200,000 surface points of a rabbit heart recorded at 200 frames/s and validate our results on highly contrasting heart motions during normal sinus rhythm, ventricular pacing, and ventricular fibrillation.

scholarly journals A Simplified 3D Model of Whole Heart Electrical Activity and 12-Lead ECG Generation

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Siniša Sovilj ◽  
Ratko Magjarević ◽  
Nigel H. Lovell ◽  
Socrates Dokos
Keyword(s):  
Electrical Activity ◽  
Three Dimensional ◽  
Model Complexity ◽  
Bidomain Model ◽  
Computationally Efficient ◽  
Lead System ◽  
Heart Electrical Activity ◽  
Cell Tissue ◽  
Whole Heart ◽  
Electrocardiogram Ecg

We present a computationally efficient three-dimensional bidomain model of torso-embedded whole heart electrical activity, with spontaneous initiation of activation in the sinoatrial node, incorporating a specialized conduction system with heterogeneous action potential morphologies throughout the heart. The simplified geometry incorporates the whole heart as a volume source, with heart cavities, lungs, and torso as passive volume conductors. We placed four surface electrodes at the limbs of the torso: , , and and six electrodes on the chest to simulate the Einthoven, Goldberger-augmented and precordial leads of a standard 12-lead system. By placing additional seven electrodes at the appropriate torso positions, we were also able to calculate the vectorcardiogram of the Frank lead system. Themodel was able to simulate realistic electrocardiogram (ECG) morphologies for the 12 standard leads, orthogonal , , and leads, as well as the vectorcardiogram under normal and pathological heart states. Thus, simplified and easy replicable 3D cardiac bidomain model offers a compromise between computational load and model complexity and can be used as an investigative tool to adjust cell, tissue, and whole heart properties, such as setting ischemic lesions or regions of myocardial infarction, to readily investigate their effects on whole ECG morphology.

scholarly journals On the Role of Ionic Modeling on the Signature of Cardiac Arrhythmias for Healthy and Diseased Hearts

Mathematics ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 2242
Author(s):  
William A. Ramírez ◽  
Alessio Gizzi ◽  
Kevin L. Sack ◽  
Simonetta Filippi ◽  
Julius M. Guccione ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Cardiac Arrhythmias ◽  
Large Scale ◽  
Structural Parameters ◽  
Computational Cost ◽  
Three Dimensional ◽  
Electrophysiological Properties ◽  
Modeling Approaches ◽  
In Silico Studies ◽  
Whole Heart

Computational cardiology is rapidly becoming the gold standard for innovative medical treatments and device development. Despite a worldwide effort in mathematical and computational modeling research, the complexity and intrinsic multiscale nature of the heart still limit our predictability power raising the question of the optimal modeling choice for large-scale whole-heart numerical investigations. We propose an extended numerical analysis among two different electrophysiological modeling approaches: a simplified phenomenological one and a detailed biophysical one. To achieve this, we considered three-dimensional healthy and infarcted swine heart geometries. Heterogeneous electrophysiological properties, fine-tuned DT-MRI -based anisotropy features, and non-conductive ischemic regions were included in a custom-built finite element code. We provide a quantitative comparison of the electrical behaviors during steady pacing and sustained ventricular fibrillation for healthy and diseased cases analyzing cardiac arrhythmias dynamics. Action potential duration (APD) restitution distributions, vortex filament counting, and pseudo-electrocardiography (ECG) signals were numerically quantified, introducing a novel statistical description of restitution patterns and ventricular fibrillation sustainability. Computational cost and scalability associated with the two modeling choices suggests that ventricular fibrillation signatures are mainly controlled by anatomy and structural parameters, rather than by regional restitution properties. Finally, we discuss limitations and translational perspectives of the different modeling approaches in view of large-scale whole-heart in silico studies.

scholarly journals Using high-resolution displays for high-resolution cardiac data

2009 ◽  
Vol 367 (1898) ◽  
pp. 2667-2677 ◽  
Author(s):  
Christopher Goodyer ◽  
John Hodrien ◽  
Jason Wood ◽  
Peter Kohl ◽  
Ken Brodlie
Keyword(s):  
High Resolution ◽  
Liquid Crystal Display ◽  
Three Dimensional ◽  
Rabbit Heart ◽  
Input Devices ◽  
Tiled Display ◽  
Interactive Display ◽  
Liquid Crystal Display Panel ◽  
Display Walls ◽  
Magnetic Resonance Imaging Scanning

The ability to perform fast, accurate, high-resolution visualization is fundamental to improving our understanding of anatomical data. As the volumes of data increase from improvements in scanning technology, the methods applied to visualization must evolve. In this paper, we address the interactive display of data from high-resolution magnetic resonance imaging scanning of a rabbit heart and subsequent histological imaging. We describe a visualization environment involving a tiled liquid crystal display panel display wall and associated software, which provides an interactive and intuitive user interface. The oView software is an OpenGL application that is written for the VR Juggler environment. This environment abstracts displays and devices away from the application itself, aiding portability between different systems, from desktop PCs to multi-tiled display walls. Portability between display walls has been demonstrated through its use on walls at the universities of both Leeds and Oxford. We discuss important factors to be considered for interactive two-dimensional display of large three-dimensional datasets, including the use of intuitive input devices and level of detail aspects.

Patterns of wave break during ventricular fibrillation in isolated swine right ventricle

2001 ◽  
Vol 281 (1) ◽  
pp. H253-H265 ◽  
Author(s):  
Moon-Hyoung Lee ◽  
Zhilin Qu ◽  
Gregory A. Fishbein ◽  
Scott T. Lamp ◽  
Eugene H. Chang ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Transmembrane Potential ◽  
Three Dimensional ◽  
Single Mechanism ◽  
Tissue Surface ◽  
Potential Recording ◽  
Surface Patterns ◽  
Optical Maps ◽  
Target Wave ◽  
Wave Break

Several different patterns of wave break have been described by mapping of the tissue surface during fibrillation. However, it is not clear whether these surface patterns are caused by multiple distinct mechanisms or by a single mechanism. To determine the mechanism by which wave breaks are generated during ventricular fibrillation, we conducted optical mapping studies and single cell transmembrane potential recording in six isolated swine right ventricles (RV). Among 763 episodes of wave break (0.75 times · s−1· cm−2), optical maps showed three patterns: 80% due to a wave front encountering the refractory wave back of another wave, 11.5% due to wave fronts passing perpendicular to each other, and 8.5% due to a new (target) wave arising just beyond the refractory tail of a previous wave. Computer simulations of scroll waves in three-dimensional tissue showed that these surface patterns could be attributed to two fundamental mechanisms: head-tail interactions and filament break. We conclude that during sustained ventricular fibrillation in swine RV, surface patterns of wave break are produced by two fundamental mechanisms: head-tail interaction between waves and filament break.

scholarly journals Three-dimensional whole-heart vs. two-dimensional high-resolution perfusion-CMR: a pilot study comparing myocardial ischaemic burden

2015 ◽  
Vol 17 (8) ◽  
pp. 900-908 ◽  
Author(s):  
Adam K. McDiarmid ◽  
David P. Ripley ◽  
Kevin Mohee ◽  
Sebastian Kozerke ◽  
John P. Greenwood ◽  
...  
Keyword(s):  
Pilot Study ◽  
High Resolution ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Whole Heart ◽  
Perfusion Cmr ◽  
Ischaemic Burden

High Resolution Microscopy of Multi-Layered Biological Crystals

1982 ◽  
Vol 40 ◽  
pp. 80-83
Author(s):  
H.A. Cohen ◽  
T.W. Jeng ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Low Dose ◽  
Three Dimensional ◽  
Data Interpretation ◽  
Two Dimensional ◽  
Biological Objects ◽  
Density Maps ◽  
Density Map ◽  
Complex Crystal ◽  
High Resolution Microscopy

This tutorial will discuss the methodology of low dose electron diffraction and imaging of crystalline biological objects, the problems of data interpretation for two-dimensional projected density maps of glucose embedded protein crystals, the factors to be considered in combining tilt data from three-dimensional crystals, and finally, the prospects of achieving a high resolution three-dimensional density map of a biological crystal. This methodology will be illustrated using two proteins under investigation in our laboratory, the T4 DNA helix destabilizing protein gp32*I and the crotoxin complex crystal.

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