scholarly journals An Image-Based Model of the Whole Human Heart with Detailed Anatomical Structure and Fiber Orientation

2012 ◽  
Vol 2012 ◽  
pp. 1-16 ◽  
Author(s):  
Dongdong Deng ◽  
Peifeng Jiao ◽  
Xuesong Ye ◽  
Ling Xia
Keyword(s):  
Human Heart ◽  
Atrioventricular Node ◽  
Linear Interpolation ◽  
Crista Terminalis ◽  
Electrophysiological Properties ◽  
Computed Tomography Images ◽  
Atrioventricular Ring ◽  
Fibers Orientation ◽  
Whole Heart ◽  
Experimental Findings

Many heart anatomy models have been developed to study the electrophysiological properties of the human heart. However, none of them includes the geometry of the whole human heart. In this study, an anatomically detailed mathematical model of the human heart was firstly reconstructed from the computed tomography images. In the reconstructed model, the atria consisted of atrial muscles, sinoatrial node, crista terminalis, pectinate muscles, Bachmann’s bundle, intercaval bundles, and limbus of the fossa ovalis. The atrioventricular junction included the atrioventricular node and atrioventricular ring, and the ventricles had ventricular muscles, His bundle, bundle branches, and Purkinje network. The epicardial and endocardial myofiber orientations of the ventricles and one layer of atrial myofiber orientation were then measured. They were calculated using linear interpolation technique and minimum distance algorithm, respectively. To the best of our knowledge, this is the first anatomically-detailed human heart model with corresponding experimentally measured fibers orientation. In addition, the whole heart excitation propagation was simulated using a monodomain model. The simulated normal activation sequence agreed well with the published experimental findings.

Heterogeneous three-dimensional anatomical and electrophysiological model of human atria

2006 ◽  
Vol 364 (1843) ◽  
pp. 1465-1481 ◽  
Author(s):  
Gunnar Seemann ◽  
Christine Höper ◽  
Frank B Sachse ◽  
Olaf Dössel ◽  
Arun V Holden ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Longitudinal Direction ◽  
Cell Types ◽  
Pacemaker Activity ◽  
Crista Terminalis ◽  
Heterogeneous Distribution ◽  
Electrophysiological Properties ◽  
Atrial Electrophysiology ◽  
Atrioventricular Ring ◽  
The Right

Investigating the mechanisms underlying the genesis and conduction of electrical excitation in the atria at physiological and pathological states is of great importance. To provide knowledge concerning the mechanisms of excitation, we constructed a biophysical detailed and anatomically accurate computer model of human atria that incorporates both structural and electrophysiological heterogeneities. The three-dimensional geometry was extracted from the visible female dataset. The sinoatrial node (SAN) and atrium, including crista terminalis (CT), pectinate muscles (PM), appendages (APG) and Bachmann's bundle (BB) were segmented in this work. Fibre orientation in CT, PM and BB was set to local longitudinal direction. Descriptions for all used cell types were based on modifications of the Courtemanche et al . model of a human atrial cell. Maximum conductances of , and were modified for PM, CT, APG and atrioventricular ring to reproduce measured action potentials (AP). Pacemaker activity in the human SAN was reproduced by removing , but including , , and gradients of channel conductances as described in previous studies for heterogeneous rabbit SAN. Anisotropic conduction was computed with a monodomain model using the finite element method. The transversal to longitudinal ratio of conductivity for PM, CT and BB was 1 : 9. Atrial working myocardium (AWM) was set to be isotropic. Simulation of atrial electrophysiology showed initiation of APs in the SAN centre. The excitation spread afterwards to the periphery near to the region of the CT and preferentially towards the atrioventricular region. The excitation extends over the right atrium along PM. Both CT and PM activated the right AWM. Earliest activation of the left atrium was through BB and excitation spread over to the APG. The conduction velocities were 0.6 m s −1 for AWM, 1.2 m s −1 for CT, 1.6 m s −1 for PM and 1.1 m s −1 for BB at a rate of 63 bpm. The simulations revealed that bundles form dominant pathways for atrial conduction. The preferential conduction towards CT and along PM is comparable with clinical mapping. Repolarization is more homogeneous than excitation due to the heterogeneous distribution of electrophysiological properties and hence the action potential duration.

scholarly journals A Systematic Exposition of Methods used for Quantification of Heart Regeneration after Apex Resection in Zebrafish

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 548 ◽  
Author(s):  
Helene Juul Belling ◽  
Wolfgang Hofmeister ◽  
Ditte Caroline Andersen
Keyword(s):  
Human Heart ◽  
Quantitative Methods ◽  
Heart Function ◽  
Heart Regeneration ◽  
Cardiomyocyte Proliferation ◽  
Ability To Regenerate ◽  
Specific Proteins ◽  
Heart Injury ◽  
Whole Heart ◽  
Study Designs

Myocardial infarction (MI) is a worldwide condition that affects millions of people. This is mainly caused by the adult human heart lacking the ability to regenerate upon injury, whereas zebrafish have the capacity through cardiomyocyte proliferation to fully regenerate the heart following injury such as apex resection (AR). But a systematic overview of the methods used to evidence heart regrowth and regeneration in the zebrafish is lacking. Herein, we conducted a systematical search in Embase and Pubmed for studies on heart regeneration in the zebrafish following injury and identified 47 AR studies meeting the inclusion criteria. Overall, three different methods were used to assess heart regeneration in zebrafish AR hearts. 45 out of 47 studies performed qualitative (37) and quantitative (8) histology, whereas immunohistochemistry for various cell cycle markers combined with cardiomyocyte specific proteins was used in 34 out of 47 studies to determine cardiomyocyte proliferation qualitatively (6 studies) or quantitatively (28 studies). For both methods, analysis was based on selected heart sections and not the whole heart, which may bias interpretations. Likewise, interstudy comparison of reported cardiomyocyte proliferation indexes seems complicated by distinct study designs and reporting manners. Finally, six studies performed functional analysis to determine heart function, a hallmark of human heart injury after MI. In conclusion, our data implies that future studies should consider more quantitative methods eventually taking the 3D of the zebrafish heart into consideration when evidencing myocardial regrowth after AR. Furthermore, standardized guidelines for reporting cardiomyocyte proliferation and sham surgery details may be considered to enable inter study comparisons and robustly determine the effect of given genes on the process of heart regeneration.

Propagation of impulses through the atrioventricular node

1959 ◽  
Vol 197 (6) ◽  
pp. 1171-1174 ◽  
Author(s):  
Jesús Alanís ◽  
Enrique López ◽  
Juan J. Mandoki ◽  
Guillermo Pilar
Keyword(s):  
Action Potential ◽  
Atrioventricular Node ◽  
The Other ◽  
Temporal Course ◽  
Bundle Of His ◽  
Experimental Findings

Records taken from the bundle of His and A-V node region of isolated and perfused dogs' hearts showed an action potential (N potential), which appeared after the auricular response and preceding the electrogram of the bundle of His (H potential). The H potential may disappear without affecting the N potential and the latter may be abolished while the auricular electrogram is still present. These observations permit the interpretation that the N potential is generated independently. The temporal course and the time of occurrence of the N potential, indicate that it represents the activity of the A-V node. The N potential divides the A-H interval into A-N and N-H latencies. Progressively increasing frequencies of activation of the auricle lengthened first the N-H latency until the H potential disappeared. Higher frequencies lengthened the A-N latency until the N potential also disappeared. In order to explain the experimental findings, it is suggested that there are two functional discontinuities, one located between the A-V node and the bundle of His, and the other between the atrium and the A-V node; the first is the most vulnerable for propagation.

Atrioventricular nodal conduction during atrial fibrillation in rabbit heart

1982 ◽  
Vol 243 (5) ◽  
pp. H754-H760 ◽  
Author(s):  
T. Mazgalev ◽  
L. S. Dreifus ◽  
J. Bianchi ◽  
E. L. Michelson
Keyword(s):  
Atrial Fibrillation ◽  
Action Potentials ◽  
Atrioventricular Node ◽  
Interatrial Septum ◽  
Rabbit Heart ◽  
Relative Timing ◽  
Crista Terminalis ◽  
His Bundle ◽  
Atrioventricular Nodal Conduction ◽  
Variable Interaction

Atrial fibrillation was induced in 15 superfused rabbit atrial-atrioventricular nodal preparations in which surface bipolar electrograms were recorded simultaneously from the crista terminalis, interatrial septum, and His bundle along with microelectrode action potentials from cells in the atrionodal (AN), nodal (N), and nodal-His (NH) regions of the atrioventricular node. Effective engagement of the atrioventricular node with propagation to the His bundle was critically dependent on the relative timing of activation at the crista terminalis and interatrial septal input regions of the atrioventricular node. Conduction through the AN and N regions appeared dependent on the relative timing of activation wave fronts emerging from the two input regions. Asynchronous engagement of AN and N regions resulted in both distortion of action potentials and concealed conduction, with delayed conduction and block to the NH region and His bundle. Successful engagement of the NH region always produced a 1:1 NH-to-His bundle relationship. It is concluded that during atrial fibrillation 1) activation of the AN region occurs as a result of the variable interaction of inputs from the crista terminalis and interatrial septum; 2) predictably, effective synchronous engagement of the AN and consequently the N region is responsible for conduction to the NH and His bundle regions; 3) conversely, asynchronous activation inputs from the crista terminalis and interatrial septum result in fragmented, asynchronous as well as concealed conduction within the AN and N regions with block in the atrioventricular node and variable conduction to the His bundle.

scholarly journals Effect of Atrial Stimulation Site on the Electrophysiological Properties of the Atrioventricular Node in Man

Circulation ◽  
1974 ◽  
Vol 50 (2) ◽  
pp. 283-292 ◽  
Author(s):  
WILLIAM P. BATSFORD ◽  
MASOOD AKHTAR ◽  
ANTONIO R. CARACTA ◽  
MARK E. JOSEPHSON ◽  
STUART F. SEIDES ◽  
...  
Keyword(s):  
Atrioventricular Node ◽  
Stimulation Site ◽  
Electrophysiological Properties ◽  
Atrial Stimulation

Randomized Study of Propofol Effect On Electrophysiological Properties of the Atrioventricular Node in Patients with Nodal Reentrant Tachycardia

2006 ◽  
Vol 29 (12) ◽  
pp. 1375-1382 ◽  
Author(s):  
PAULO WARPECHOWSKI ◽  
GUSTAVO G. LIMA ◽  
CLÁUDIO M. MEDEIROS ◽  
ARI TADEU L. SANTOS ◽  
MARCELO KRUSE ◽  
...  
Keyword(s):  
Randomized Study ◽  
Atrioventricular Node ◽  
Reentrant Tachycardia ◽  
Electrophysiological Properties

scholarly journals Hierarchical Timescales in the Neocortex: Mathematical Mechanism and Biological Insights

2021 ◽  
Author(s):  
Songting Li ◽  
Xiao-Jing Wang
Keyword(s):  
Large Scale ◽  
Detailed Balance ◽  
Receptive Fields ◽  
Spatial Summation ◽  
Progressive Increase ◽  
Connectivity Matrix ◽  
Electrophysiological Properties ◽  
Neuronal Populations ◽  
Sensory Neural ◽  
Experimental Findings

A cardinal feature of the neocortex is the progressive increase of the spatial receptive fields along the cortical hierarchy. Recently, theoretical and experimental findings have shown that the temporal response windows also gradually enlarge, so that early sensory neural circuits operate on short-time scales whereas higher association areas are capable of integrating information over a long period of time. While an increased receptive field is accounted for by spatial summation of inputs from neurons in an upstream area, the emergence of timescale hierarchy cannot be readily explained, especially given the dense inter-areal cortical connectivity known in modern connectome. To uncover the required neurobiological properties, we carried out a rigorous analysis of an anatomically-based large-scale cortex model of macaque monkeys. Using a perturbation method, we show that the segregation of disparate timescales is defined in terms of the localization of eigenvectors of the connectivity matrix, which depends on three circuit properties: (1) a macroscopic gradient of synaptic excitation, (2) distinct electrophysiological properties between excitatory and inhibitory neuronal populations, and (3) a detailed balance between long-range excitatory inputs and local inhibitory inputs for each area-to-area pathway. Our work thus provides a quantitative understanding of the mechanism underlying the emergence of timescale hierarchy in large-scale primate cortical networks.

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.

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