Tetralogy of Fallot exhibits squatting symptoms because squatting involves flexing the lower limbs, which reduces the amount of venous return to the heart, thereby decreasing the cardiac workload. At the same time, the arteries of the lower limbs are compressed, increasing systemic vascular resistance, reducing right-to-left shunting, and temporarily alleviating hypoxia symptoms. Infants who cannot walk often prefer to be held with their thighs up, with both lower limbs bent; after they become able to walk, they frequently squat down momentarily during walking or playing.