REN and hydrops fetalis: In addition, the renin‐angiotensin‐aldosterone system (RAAS) plays a key role in regulating blood pressure and volume homeostasis in the process of HF,7 while angiotensin II (Ang II) is a core component of the renin‐angiotensin‐angiotensin system (RAS) and plays a key role in the occurrence and development of cardiac remodeling.8