The heart has its own blood supply

The heart has its own blood supply.

The coronary arteries are the first branches of the aorta. They supply the myocardium and endocardium with oxygenated blood. The 2 main coronary arteries, the left coronary artery and the right coronary artery (Figure 3), branch into a complex network of arteries that supply all areas of the heart. The left main coronary artery divides into the left anterior descending (LAD) and left circumflex (LCX) coronary arteries

Cardiac contraction occurs first in the atria and then the ventricles. Atrioventricular synchrony contributes to the normal function of the heart. Atrial contraction adds 15% to 20%

to the cardiac output under normal physiologic conditions. However, an inherent delay in

electrical activation of the ventricles is necessary for mechanical emptying of the atria to

occur. The delay of the electrical conduction through the atrioventricular (AV) node allows time for the slower mechanical contraction to occur.