ARG1 and hydrops fetalis: A few reports revealed that arginase 2 protein levels are increased in murine mdx dystrophic heart (Wehling‐Henricks et al. 2010) and in pacing‐induced failing left ventricle (LV) of rabbits (Heusch et al. 2010), and circulating arginase 1 levels are increased in human HF (Quitter et al. 2013).