RYR2 and hydrops fetalis: During HF, impaired Ca2+ uptake due to dysregulation in several calcium cycling proteins and increased SR Ca2+ leak through type-2 ryanodine receptors (RyR2) resulting in reduced intracellular Ca2+ stores required for cardiomyocyte contraction and increased baseline cytosolic Ca2+ [45,46,47,48,49,50].