The coronary circulation is the circulatory system of the heart which allows the blood supply to the cardiac muscle and endocardium. The oxygen-rich blood is conveyed by the left and right coronary arteries and its branches, while the drainage of the deoxygenated (oxygen-depleted) blood is carried out by the great cardiac vein as well as by the anterior cardiac, posterior left ventricular, and the middle cardiac vein. Both coronary arteries arise from the aortic sinuses (sinuses of Valsalva) at the root of the aorta and they each gets filled up with flowing blood during each cardiac systole (ventricular contraction).
In human beings, the coronary circulation essentially consists of the right and left coronary arteries, which begin at the base of the aorta. These two main arteries divide and forks into smaller branches to supply the whole myocardium. There are three types of blood supply to the heart: right coronary, left coronary, and general, which in some measure determine the nature of the pathology of the coronary circulation in the event of disease of the heart vessels. The cardiac veins, on the other hand, are both larger and greater in number than the arteries. The veins empty into the right atrium. The principal arterial and venous trunks are connected by a well-developed network of anastomoses, which facilitates collateral (shunt) circulation in cases of impairment of blood supply to the heart.
The coronary circulation is completed by a dense network of capillaries (approximately twice the number per unit volume than in the skeletal muscles) which supply and drain the heart. Effectively, the arterioles (smallest arterial branches) is connected to the venules (smallest veins) by these capillaries, which pour the arterial oxygenated blood into the myocardium but also pick up deoxygenated blood that is carried into the venules. The level of the coronary circulation in a healthy body corresponds exactly to the force and frequency of the heartbeat.
The coronary circulation is regulated both by physical factors (for example, blood pressure in the aorta) and by neural and humoral mechanisms. Thus, we can say that coronary circulation is influenced by physical and mental condition and by the degree and character of stress or load. It is sharply impaired by nicotine and certain factors that lead to atherosclerosis, hypertension, and cardiac ischemia, such as overstrain of the nervous system, negative emotions, improper nutrition, and the absence of constant physical exercise. Coronary insufficiency and disturbances of coronary circulation are among the most frequent causes of death in economically developed countries, and therefore their prevention and treatment (mainly of infarction) are the most pressing problems of modern medicine.
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| Above, anterior view of human heart, showing arteries and veins of the coronary circulation. |