Heart tissue, like all tissues in the body, needs a supply of oxygen, nutrients, and a way to get rid of metabolic waste. This is achieved through the coronary circulation, which includes arteries, veins, and lymphatic vessels. Blood flows through the coronary vessels at a frequency related to the relaxation and contraction of the heart muscle.[9]
The heart tissue receives blood from two arteries that emerge from the aorta just above the valve, the left coronary artery, which is the main artery, and the right coronary artery. The left coronary artery divides shortly after its origin into two arteries, the left anterior descending artery and the left circumflex artery. The left anterior descending artery supplies the left ventricle (heart tissue, periphery, and septum) by branching into smaller arteries. The left circumflex artery perfuses the posterior and inferior surfaces of the left ventricle. The right coronary artery supplies the right atrium, the right ventricle, and the lower posterior portions of the left ventricle. The sinoatrial node is perfused from the right coronary artery (in about 60% of cases), and the atrioventricular node is also supplied from the right coronary artery (in about 90% of cases). The right coronary artery runs in a groove on the back of the heart, while the left anterior descending artery runs in a groove on the front of the heart. People show great variations in the anatomy of the arteries that irrigate the heart.[27]
The coronary sinus is the large vein that drains into the right atrium, and receives blood from most of the cardiac venous drainage, as it receives blood from the great cardiac vein (which in turn receives blood from the left atrium and both ventricles) and the posterior cardiac vein (draining blood from the back of the left ventricle ) and the middle cardiac vein (blood drains the bottom of the right and left ventricles) and the small cardiac veins.[28] The anterior cardiac veins drain blood from the front of the right ventricle and drain directly into the right atrium.[9]
There are small lymphatic networks located under the three layers of the heart wall called plexuses. These networks are combined into the left and right main trunks, which pass from the interventricular groove on the surface of the heart, and receive smaller vessels as they pass through the sulcus. Then these vessels travel in the atrioventricular sulcus and receive a third vessel that drains the part of the left ventricle which is located on the diaphragm. The third vessel joins the left vessel and they travel along the pulmonary artery and the left atrium to terminate in the inferior bronchotracheal ganglion. The right vessel runs along the right atrium and part of the right ventricle which lies on the diaphragm, and then it usually runs in front of the ascending aorta and ends in the brachiocephalic ganglion.[29]
