The right coronary artery arises from the right aortic sinus of Valsalva and passes in the right atrioventricular groove. It gives the sinoatrial nodal artery in 60% of individuals, the right marginal artery, and in 85% of people the posterior descending artery (right dominant circulation), which supplies the posterior interventricular septum and the atrioventricular node. In left dominant systems the posterior descending is supplied by the left circumflex.
RCA occlusion produces inferior STEMI, recognisable by ST elevation in leads II, III, and aVF. Proximal RCA occlusion causes right ventricular infarction in addition to inferior MI, presenting with hypotension, elevated JVP, clear lung fields, and ST elevation in right-sided leads, a combination requiring volume resuscitation rather than nitrates. The RCA's supply of the sinoatrial and atrioventricular nodes explains why inferior MI frequently produces bradyarrhythmias including complete heart block. RCA disease is revascularised surgically with saphenous vein graft or percutaneously with stenting.
Proximal RCA thrombosis produces inferior myocardial infarction with ST elevation in inferior leads and risk of right ventricular involvement causing haemodynamic compromise, bradyarrhythmias from SA and AV node ischaemia, and cardiogenic shock requiring urgent primary PCI.
Proximal RCA occlusion before the right ventricular marginal branch infarcts the right ventricle, producing a paradoxical clinical picture of hypotension with elevated JVP and clear lungs requiring aggressive IV fluid resuscitation, distinguishing it from left ventricular failure.
