Electrophysiology and Tension Development in a Transmural Heterogeneous Model of the Visible Female Left Ventricle

2005 ◽  
pp. 172-182 ◽  
Author(s):  
Gunnar Seemann ◽  
Daniel L. Weiß ◽  
Frank B. Sachse ◽  
Olaf Dössel
Keyword(s):  
Left Ventricle ◽  
Tension Development ◽  
Heterogeneous Model

scholarly journals Drift of Scroll Waves in a Mathematical Model of a Heterogeneous Human Heart Left Ventricle

Mathematics ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 776
Author(s):  
Sergey Pravdin ◽  
Pavel Konovalov ◽  
Hans Dierckx ◽  
Olga Solovyova ◽  
Alexander V. Panfilov
Keyword(s):  
Left Ventricle ◽  
Homogeneous Model ◽  
Heterogeneous Model ◽  
Wave Dynamics ◽  
Ventricular Cells ◽  
Large Heterogeneity ◽  
Scroll Wave ◽  
Spatio Temporal ◽  
Human Left Ventricle ◽  
Transmural Heterogeneity

Rotating spiral waves of electrical excitation underlie many dangerous cardiac arrhythmias. The heterogeneity of myocardium is one of the factors that affects the dynamics of such waves. In this paper, we present results of our simulations for scroll wave dynamics in a heterogeneous model of the human left ventricle with analytical anatomically based representation of the geometry and anisotropy. We used a set of 18 coupled differential equations developed by ten Tusscher and Panfilov (TP06 model) which describes human ventricular cells based on their measured biophysical properties. We found that apicobasal heterogeneity dramatically changes the scroll wave dynamics. In the homogeneous model, the scroll wave annihilates at the base, but the moderate heterogeneity causes the wave to move to the apex and then continuously rotates around it. The rotation speed increased with the degree of the heterogeneity. However, for large heterogeneity, we observed formation of additional wavebreaks and the onset of complex spatio-temporal patterns. Transmural heterogeneity did not change the dynamics and decreased the lifetime of the scroll wave with an increase in heterogeneity. Results of our numerical experiments show that the apex may be a preferable location of the scroll wave, which may be important for development of clinical interventions.

Mechanics of Active Contraction in Cardiac Muscle: Part II—Cylindrical Models of the Systolic Left Ventricle

1993 ◽  
Vol 115 (1) ◽  
pp. 82-90 ◽  
Author(s):  
J. M. Guccione ◽  
L. K. Waldman ◽  
A. D. McCulloch
Keyword(s):  
Left Ventricle ◽  
Cardiac Muscle ◽  
Sarcomere Length ◽  
Left Ventricular ◽  
Isometric Tension ◽  
Fiber Stress ◽  
Tension Development ◽  
Deactivation Model ◽  
Biomechanical Engineering ◽  
Asme Journal

Models of contracting ventricular myocardium were used to study the effects of different assumptions concerning active tension development on the distributions of stress and strain in the equatorial region of the intact left ventricle during systole. Three models of cardiac muscle contraction were incorporated in a cylindrical model for passive left ventricular mechanics developed previously [Guccione et al. ASME Journal of Biomechanical Engineering, Vol. 113, pp. 42-55 (1991)]. Systolic sarcomere length and fiber stresses predicted by a general “deactivation” model of cardiac contraction [Guccione and McCulloch, ASME Journal of Biomechanical Engineering, Vol. 115, pp. 72-81 (1993)] were compared with those computed using two less complex models of active fiber stress: In a time-varying “elastance” model, isometric tension development was computed from a function of peak intracellular calcium concentration, time after contraction onset and sarcomere length; a “Hill” model was formulated by scaling this isometric tension using the force-velocity relation derived from the deactivation model. For the same calcium ion concentration, the sarcomeres in the deactivation model shortened approximately 0.1 μm less throughout the wall at end-systole than those in the other models. Thus, muscle fibers in the intact ventricle are subjected to rapid length changes that cause deactivation during the ejection phase of a normal cardiac cycle. The deactivation model predicted rather uniform transmural profiles of fiber stress and cross-fiber stress distributions that were almost identical to those of the radial component. These three components were indistinguishable from the principal stresses. Transmural strain distributions predicted at end-systole by the deactivation model agreed closely with experimental measurements from the anterior free wall of the canine left ventricle.

scholarly journals A structure-function analysis of the left ventricle

2016 ◽  
Vol 121 (4) ◽  
pp. 900-909 ◽  
Author(s):  
Edward P. Snelling ◽  
Roger S. Seymour ◽  
J. E. F. Green ◽  
Leith C. R. Meyer ◽  
Andrea Fuller ◽  
...  
Keyword(s):  
Left Ventricle ◽  
Structure Function ◽  
Function Analysis ◽  
Left Ventricular ◽  
Work Rate ◽  
Ovis Aries ◽  
Capra Hircus ◽  
Heavy Exercise ◽  
Tension Development ◽  
Arterial Blood

This study presents a structure-function analysis of the mammalian left ventricle and examines the performance of the cardiac capillary network, mitochondria, and myofibrils at rest and during simulated heavy exercise. Left ventricular external mechanical work rate was calculated from cardiac output and systemic mean arterial blood pressure in resting sheep ( Ovis aries; n = 4) and goats ( Capra hircus; n = 4) under mild sedation, followed by perfusion-fixation of the left ventricle and quantification of the cardiac capillary-tissue geometry and cardiomyocyte ultrastructure. The investigation was then extended to heavy exercise by increasing cardiac work according to published hemodynamics of sheep and goats performing sustained treadmill exercise. Left ventricular work rate averaged 0.017 W/cm3 of tissue at rest and was estimated to increase to ∼0.060 W/cm3 during heavy exercise. According to an oxygen transport model we applied to the left ventricular tissue, we predicted that oxygen consumption increases from 195 nmol O2·s−1·cm−3 of tissue at rest to ∼600 nmol O2·s−1·cm−3 during heavy exercise, which is within 90% of the oxygen demand rate and consistent with work remaining predominantly aerobic. Mitochondria represent 21-22% of cardiomyocyte volume and consume oxygen at a rate of 1,150 nmol O2·s−1·cm−3 of mitochondria at rest and ∼3,600 nmol O2·s−1·cm−3 during heavy exercise, which is within 80% of maximum in vitro rates and consistent with mitochondria operating near their functional limits. Myofibrils represent 65–66% of cardiomyocyte volume, and according to a Laplacian model of the left ventricular chamber, generate peak fiber tensions in the range of 50 to 70 kPa at rest and during heavy exercise, which is less than maximum tension of isolated cardiac tissue (120–140 kPa) and is explained by an apparent reserve capacity for tension development built into the left ventricle.

609 Noninvasive left ventricle contractility assessment in patients with long-term volume overload

1999 ◽  
Vol 1 ◽  
pp. S101-S101
Author(s):  
O FOKINA ◽  
N TVERDOKHLEBOV ◽  
V SANDRIKOV ◽  
L KOUZNETZOVA
Keyword(s):  
Left Ventricle ◽  
Volume Overload
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