Our major findings are: (1) cardiac miR-199a-5p expression was increased in the HF heart tissues compared with the sham-operation group, and JunB expression was relatively lower in the HF group; (2) mir-199a-5p expression increased and JunB expression decreased after stimulation with Ang II; (3) miR-199a-5p promoted apoptosis induced by Ang II stimulation; (4) Jun B was a direct target of miR-199a-5p; and 5) JunB played a protective role in myocardial apoptosis. The gene discussed is AGT; the disease is hydrops fetalis.