1,721,023 research outputs found
Discretizzazione della superficie toracica e di volumi conduttori extra ed intracardiaci per lo studio di campi elettrici cardiaci tridimensionali.
No full textBody surface potential maps preserving the topological properties of the thoracic surface.
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Modeling ventricular repolarization: effects of transmural and apex-to-base heterogeneities in action potential durations
No full textAdvanced multiscale models in computational electrocardiology offer
a detailed representation of the heart bioelectrical activity,
ranging from the microscopic description of ion channels of the
cellular membrane to the macroscopic properties of anisotropic
front propagation in the whole heart. Our model consists of a
Monodomain or Bidomain tissue representation that includes
orthotropic anisotropy, transmural fiber rotation and
homogeneous or heterogeneous intrinsic membrane properties,
described by Luo-Rudy type models. We consider membrane heterogeneities
due either to the presence of midwall cells (M-cells) with different
action potential durations (APDs) or to the presence of subendocardial
ischemic regions. We present the results of large-scale simulations of
an entire heartbeat with epicardial or endocardial pacing of three-dimensional
ventricular blocks. We will also discuss some numerical features of our simulations,
including parallel scalability, multilevel preconditioning and space-time adaptivity
Epicardial excitation during ventricular pacing. Relative independence of breakthrough sites from excitation sequence in canine right ventricle.
No full textMultiple components in the unipolar electrocardiogram: a simulation study in a three-dimensional model of ventricular myocardium
No full textEpicardial and intramural excitation during ventricular pacing: effect of myocardial structure.
No full textPublished studies show that ventricular pacing in canine hearts produces three distinct patterns of epicardial excitation: elliptical isochrones near an epicardial pacing site, with asymmetric bulges; areas with high propagation velocity, up to 2 or 3 m/s and numerous breakthrough sites; and lower velocity areas (<1 m/s), where excitation moves across the epicardial projection of the septum. With increasing pacing depth, the magnitude of epicardial potential maxima becomes asymmetric. The electrophysiological mechanisms that generate the distinct patterns have not been fully elucidated. In this study, we investigated those mechanisms experimentally. Under pentobarbital anesthesia, epicardial and intramural excitation isochrone and potential maps have been recorded from 22 exposed or isolated dog hearts, by means of epicardial electrode arrays and transmural plunge electrodes. In five experiments, a ventricular cavity was perfused with diluted Lugol solution. The epicardial bulges result from electrotonic attraction from the helically shaped subepicardial portions of the wave front. The high-velocity patterns and the associated multiple breakthroughs are due to involvement of the Purkinje network. The low velocity at the septum crossing is due to the missing Purkinje involvement in that area. The asymmetric magnitude of the epicardial potential maxima and the shift of the breakthrough sites provoked by deep stimulation are a consequence of the epi-endocardial obliqueness of the intramural fibers. These results improve our understanding of intramural and epicardial propagation during premature ventricular contractions and paced beats. This can be useful for interpreting epicardial maps recorded at surgery or inversely computed from body surface ECGs
Effects of transmural electric heterogeneities and electrotonic interactions on the dispersion of cardiac repolarization and action potential duration. A simulation study
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