SRF and hydrops fetalis: Forced circSlc8a1 expression in mouse heart via an AAV9-based vector system would result in HF via regulating the expression of serum response factor (Srf), connective tissue growth factor (CTGF), β1-adrenergic receptor (β1-AR) via miR-133a or adenylate cyclase 6 (Adcy6) directly.