The reduced Ca2+ spark amplitude and width as well as increased Ca2+ spark TTP in CMCs from MKO mice 7 days after TAC are consistent with the published observations in CMCs with reduced CASQ2 levels (Terentyev et al., 2003), and may thus be explained by the reduced CASQ2 levels in MKO mice 4 days after TAC. Here, CASQ2 is linked to persistent truncus arteriosus.