Isochrones were displayed both during sinus rhythm and AF.Results During sinus rhythm,the atrial excitation wave front begins from sinus node spreading to right atrium(RA)and left atrium(LA).
Meanwhile, the inner serous pericardium consists of an inner visceral layer, or epicardium — which is actually part of the heart wall — and an outer parietal layer.
The muscular walls of the heart consist of three major " layers" . The bulk of the walls is made up of a layer of cardiac muscle and is called the myocardium.
Whatever the case, the heart needs blood, and if we look at the heart wall, there's three layers—the outermost layer, the epicardium, then the myocardium in the middle, and the endocardium inside the heart.