PLN and hydrops fetalis: Extensive studies have suggested that alterations in calcium‐handling proteins, including ryanodine receptor 2 (RyR2), SR Ca2+‐ATPase 2a (SERCA2a), phospholamban (PLB), and sodium/calcium exchanger 1 (NCX1), contribute to changes in intracellular calcium transients and diastolic SR Ca2+ release that, in turn, lead to Ca2+‐triggered arrhythmogenesis in HF animal models.9, 25, 26, 27 Therefore, we next detected the protein expression of RyR2, SERCA2a, PLB, and NCX1 in each group.