When you click on the link below you will see a video of an angiogram of the IVC, which passes up and through the right atrium to drain exclusively to the left atrium through a stenosis. The SVC and the rest of the heart were entirely normal. This is one of a set of pathologies which can give cyanosis without right ventricular hypertension. The commoner causes are Ebstein's malformation and pulmonary arteriovenous fistula.