Right atrial procedures require snaring the venous cannulas to prevent air entrapment in the venous line. In particular situations with complex congenital morphology and/or presence of severe pericardial adhesions the right atrial opening without the inferior vena cava cannula in the surgical field and without dissecting and snaring the inferior vena cava itself, might substantially facilitate the surgical technique, provided an adequate venous drainage is assured to avoid flow reduction or circulatory arrest. In several patients with congenital or acquired heart disease with potentially complicated venous drainage, like extracardiac Fontan procedure and tricuspid valve replacement, cardiopulmonary bypass was conducted either on normothermia (congenital lesions) or with mild hypothermia (acquired disease), with 3 l/min per m2 flow index and venous drainage through femoral vein cannulation. The right atrium was opened without snaring the inferior vena cava, never provoking reduction of the venous drainage nor air locks in the venous line. This approach substantially enhanced the surgical exposure and therefore facilitated the operative technique without any negative consequence to the patients. Right atrial surgery on cardiopulmonary bypass without direct cannulation and snaring of both superior and inferior vena cava is feasible without flow reduction for surgeons taking care of both congenital and acquired cardiac lesions.