ABSTRACT
The arterial blood supply to the heart comes from the right coronary artery (RCA) and the left coronary artery (LCA), which arise from the anterior and posterior aortic sinuses respectively. The heart can autoregulate its blood supply at coronary perfusion pressures (CoPP) between 60 and 180 mmHg. Outside this range, the coronary circulation becomes pressure dependent. When endothelium is damaged the production of these vasoactive substances is reduced, making coronary vessels prone to vasospasm and platelet aggregation. ANS exerts a weak effect on the coronary circulation. α-adrenergic receptor stimulation causes vasoconstriction while β-adrenergic and vagal stimulation leads to vasodilatation of coronary vessels. Myocardial oxygen supply is determined by coronary blood flow and the arterial oxygen content. Vasoactive hormones require an intact endothelium in order to produce their effect. Atrial natriuretic peptide causes vasodilatation while vasopressin and angiotensin II cause vasoconstriction.
