We recently extended their work, by studying the synergy of Na+ handling with Ca2+ and CaMKII signaling, since CaMKII hyperactivity in HF has also been associated with late INa and intracellular [Na+] ([Na+]i) overload (Wagner et al., 2006; Grandi and Herren, 2014). This evidence concerns the gene CAMK2G and hydrops fetalis.