How can deoxygented blood reach to heart?

De oxygenated blood enters the heart through the superior and inferior vena cavas. The blood enters the right atrium. It is then pumped into the right ventricle. There is a valve known as the tricuspid valve that separates these two chambers. The blood is then pumped from the right ventricle into the pulmonary arteries. These arteries carry the blood to the lungs.