[One-dimensional time-dependent model of the cardiac pacemaker activity induced by the mechanoelectric feedback in a thermo-electro-mechanical background].
OBJECTIVE
In a healthy heart, the mechanoelectric feedback (MEF) process acts as an intrinsic regulatory mechanism of the myocardium which allows the normal cardiac contraction by damping mechanical perturbations in order to generate a new healthy electromechanical situation. However, under certain conditions, the MEF can be a generator of dramatic arrhythmias by inducing local electrical depolarizations as a result of abnormal cardiac tissue deformations, via stretch-activated channels (SACs). Then, these perturbations can propagate in the whole heart and lead to global cardiac dysfunctions. In the present study, we qualitatively investigate the influence of temperature on autonomous electrical activity generated by the MEF.


METHODS
We introduce a one-dimensional time-dependent model containing all the key ingredients that allow accounting for the excitation-contraction coupling, the MEF and the thermoelectric coupling.


RESULTS
Our simulations show that an autonomous electrical activity can be induced by cardiac deformations, but only inside a certain temperature interval. In addition, in some cases, the autonomous electrical activity takes place in a periodic way like a pacemaker. We also highlight that some properties of action potentials, generated by the mechanoelectric feedback, are significantly influenced by temperature. Moreover, in the situation where a pacemaker activity occurs, we also show that the period is heavily temperature-dependent.


CONCLUSIONS
Our qualitative model shows that the temperature is a significant factor with regards to the electromechanical behavior of the heart and more specifically, with regards to the autonomous electrical activity induced by the cardiac tissue deformations.
Cardiovascular research center, université de Liège, allée du 6-août, 17 (B5a), 4000 Liège, Belgique. A.Collet@ulg.ac.be
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D001145:Arrhythmias, Cardiac / Q000503:physiopathology / Q000628:therapy; D003198:Computer Simulation; D056966:Excitation Contraction Coupling; D005246:Feedback; D006321:Heart / Q000502:physiology / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008432:Mathematical Computing; D008955:Models, Cardiovascular; D009200:Myocardial Contraction; D010138:Pacemaker, Artificial; D015203:Reproducibility of Results; D012849:Sinoatrial Node / Q000503:physiopathology; D013314:Stress, Mechanical; D013696:Temperature