The tricuspid valve sits between the right atrium (the heart’s upper chamber that stores deoxygenated blood) and the right ventricle (the heart’s bottom chamber where blood flows to the lungs). When blood is sent to the lungs to be oxygenated, this valve is pushed open like a one-way gate. Blood rushes through the open valve into the right ventricle. In tricuspid valve regurgitation, the valve flaps (leaflets) do not close tightly after blood is pushed through. Sometimes they balloon backwards (prolapse) as they close. In regurgitation, blood that was just pumped out leaks back into the atrium. Causes include: high blood pressure that enlarges the aorta, valve infection (endocarditis), rheumatic fever, or inherited conditions (such as a valve with one or two leaflets instead of the normal three).