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 stenosis, stiff or fused leaflets block this fast outflow of blood. The narrowing is usually caused by an inherited defect, calcium build-up on the valve, or scarring from childhood rheumatic fever related to strep throat.