epas1 is also essential for the maintenance of catecholamine homeostasis and protection against heart failure during early embryonic development. catecholamines regulated by epas1 include epinephrine and norepinephrine. it is critical that the production of catecholamines remain in homeostatic conditions so that both the delicate fetal heart and the adult heart do not overexert themselves and induce heart failure. catecholamine production in the embryo is related to control of cardiac output by increasing the fetal heart rate.