KCNQ1 and hydrops fetalis: In this study, complex nodal line dynamics were observed almost exclusively in LQT1-TICM (see Fig 7 and S3 and S4 Files for LQT1-TICM vs. S5 File for LMC-TICM), suggesting the role of IKs downregulation along with abnormal Ca2+ handling in HF.