The coronary circulation consists of the coronary arteries and veins, together with the lymphatics of the heart. Because the lymphatics, apart from the thoracic duct, are of very limited significance to operative anatomy, they will not be discussed at any length in this chapter. The veins, relatively speaking, are similarly of less interest. In this chapter, therefore, we concentrate upon those anatomical aspects of arterial distribution that are pertinent to the surgeon, concluding with a brief discussion of the cardiac venous drainage and the cardiac lymphatics.
THE CORONARY ARTERIES
The coronary arteries are the first branches of the ascending portion of the aorta. They take their origin from the sinuses within the aortic root, immediately above its attachment to the heart (Figure 4.1). There are three sinuses within the aortic root, but only two coronary arteries. The sinuses can be named, therefore, according to whether they give rise to an artery, the normal arrangement being a right coronary, left coronary, and non-coronary aortic sinus (Figure 4.2). When described in this fashion, the terms ‘right’ and ‘left’ refer to the aortic sinuses giving rise to the right and left coronary arteries, rather than to the position of the sinuses relative to the right-to-left coordinates of the body (Figure 4.3). In the normal heart, the aortic root is situated obliquely, while in malformed hearts, the root is frequently positioned abnormally. Whatever the position of the aortic root, however, the two coronary arteries, when two are present, almost always take origin from those aortic sinuses that are adjacent to the sinuses of the pulmonary trunk.