small cardiac vein small cardiac vein the small cardiac vein, also known as the right coronary vein, is a coronary vein that drains parts of the right atrium and right ventricle of the heart. despite its size, it is one of the major drainage vessels for the heart. small cardiac veinbase and diaphragmatic surface of heart (small cardiac vein labeled at lower right.)arteries:rca = right coronaryab = atrial branchessanb = sinuatrial nodalrma = right marginallca = left coronarycb = circumflex branchlad/aib = anterior interventricularlma = left marginalpia/pda = posterior descendingavn = atrioventricular nodalveins:scv = small cardiacacv = anterior cardiacaiv/gcv = great cardiacmcv = middle cardiaccs = coronary sinusdetailsdrains tocoronary sinusidentifierslatinvenae cardiacae minimae, vena cordis parvata98a12.3.01.010ta24166fma4714anatomical terminology anatomy course the small cardiac vein runs in the coronary sulcus between the right atrium and right ventricle, and opens into the right extremity of the coronary sinus. territory the small cardiac vein receives blood from the posterior portion of the right atrium and ventricle. variation the small cardiac vein may empty into the coronary sinus, right atrium, or middle cardiac vein. it may be absent.