Abstract
Calcium ions (Ca2+) play a major role in the cardiac excitation-contraction coupling. Intracellular Ca2+ concentration increases during systole and falls in diastole thereby determining cardiac contraction and relaxation. Normal cardiac function also requires perfect organization of the ion currents at the cellular level to drive action potentials and to maintain action potential propagation and electrical homogeneity at the tissue level. Any imbalance in Ca2+ homeostasis of a cardiac myocyte can lead to electrical disturbances. This review aims to discuss cardiac physiology and pathophysiology from the elementary membrane processes that can cause the electrical instability of the ventricular myocytes through intracellular Ca2+ handling maladies to inherited and acquired arrhythmias. Finally, the paper will discuss the current therapeutic approaches targeting cardiac arrhythmias.
Highlights
Excitation-contraction coupling (E-C coupling) of the cardiac myocytes is a well studied phenomenon
E-C coupling has been reviewed in detail (Bers, 2002; Eisner et al, 2017), here we consider the elementary steps and the events that can lead to electrical disturbances (Figure 1)
We summarized that RSV was decreased by ion currents involved in the negative feedback regulation of AP duration (APD) (ICa,L, IKs and IKr), while it was increased by INa and Ito, and in general, increased if repolarization reserved was compromised
Summary
Excitation-contraction coupling (E-C coupling) of the cardiac myocytes is a well studied phenomenon. We know that the calcium ion (Ca2+) plays a major role in controlling contraction and force, a feature that was originally described by Sidney Ringer more than a century ago (Ringer, 1883). Since this discovery, it has become clear that changes in intracellular Ca2+ concentration ([Ca2+]i) have a significant role in virtually all parts of the human body. Of particular importance is the fact, that within cardiac myocytes, [Ca2+]i changes must be tightly regulated, so that the heart can beat rhythmically This means that during the cardiac systole, [Ca2+]i has to increase to certain levels to make contraction occur and must fall. E-C coupling has been reviewed in detail (Bers, 2002; Eisner et al, 2017), here we consider the elementary steps and the events that can lead to electrical disturbances (Figure 1)
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