Coronary artery disease definition pdf arteries labeled in red text and other landmarks in blue text. The vessels that remove the deoxygenated blood from the heart muscle are known as cardiac veins. The coronary arteries that run deep within the myocardium are referred to as subendocardial. Schematic diagram of the coronary arteries and veins.
Base and diaphragmatic surface of heart. Coronary arteries supply blood to the myocardium and other components of the heart. The left coronary artery distributes blood to the left side of the heart, the left atrium and ventricle, and the interventricular septum. Eventually, it will fuse with the small branches of the right coronary artery. It follows the anterior interventricular sulcus around the pulmonary trunk.
An anastomosis is an area where vessels unite to form interconnections that normally allow blood to circulate to a region even if there may be partial blockage in another branch. The anastomoses in the heart are very small. The marginal arteries supply blood to the superficial portions of the right ventricle. On the posterior surface of the heart, the right coronary artery gives rise to the posterior interventricular artery, also known as the posterior descending artery. It runs along the posterior portion of the interventricular sulcus toward the apex of the heart, giving rise to branches that supply the interventricular septum and portions of both ventricles.
There are some anastomoses between branches of the two coronary arteries. This is because blockage of one coronary artery generally results in death of the heart tissue due to lack of sufficient blood supply from the other branch. When two arteries or their branches join, the area of the myocardium receives dual blood supply. These junctions are called anastomoses. However, this can only occur if the atheroma progresses slowly, giving the anastomoses a chance to proliferate. Under the most common configuration of coronary arteries, there are three areas of anastomoses.
There is also an anastomosis between the septal branches of the two coronary arteries in the interventricular septum. The photograph shows area of heart supplied by the right and the left coronary arteries. In rare cases, a person will have the third coronary artery run around the root of the aorta. If the posterior descending artery is supplied by both the right coronary artery and the circumflex artery, then the coronary circulation can be classified as “co-dominant”. A precise anatomic definition of dominance would be the artery which gives off supply to the AV node i. Most of the time this is the right coronary artery. If the papillary muscles are not functioning properly, the mitral valve may leak during contraction of the left ventricle.
This causes some of the blood to travel “in reverse”, from the left ventricle to the left atrium, instead of forward to the aorta and the rest of the body. On the other hand, the posteromedial papillary muscle is usually supplied only by the PDA. This makes the posteromedial papillary muscle significantly more susceptible to ischemia. PDA is more likely to cause mitral regurgitation. Because of this, blood flow in the subendocardium stops during ventricular contraction. Flow never comes to zero in the right coronary artery, since the right ventricular pressure is less than the diastolic blood pressure. This contributes to the filling difficulties of the coronary arteries.
Chronic moderate ischemia causes contraction of the heart to weaken, known as myocardial hibernation. In addition to metabolism, the coronary circulation possesses unique pharmacologic characteristics. Prominent among these is its reactivity to adrenergic stimulation. A hypothesis for ischemic papillary muscle dysfunction”. This page was last edited on 8 October 2017, at 21:44.