How does blood return from the cardiac tissues to the right atrium

Well the blood returns from the cardiac tissues to the right atrium because
the blood goes through the tricuspid valve and into the right ventricle then the right ventricle makes the blood go to the lungs and thats where the oxygen is at then the blood goes through organs and tissues then gets to the heart through the veins and a vein named the vena cave has the blood return to the right atrium.  

Due to the amount of pressure