Physiology of the normal heart

Abstract

Cardiac physiology describes how a highly specialized muscular pump converts electrical activity into coordinated muscular work. This integration, from pacemaker automaticity and impulse propagation to calcium cycling, sarcomere contraction and ventriculo-arterial interaction, underpins normal cardiovascular performance and explains many clinical signs in disease. This short review summarizes the cellular architecture of the myocardium, the ionic basis of the cardiac action potential, excitation–contraction coupling, the phases of the cardiac cycle and the principal determinants of stroke volume and cardiac output.