HSPD1 and hydrops fetalis: This study poses HSPs as stress related proteins that may account for the therapeutic effects of transcutaneous electrical stimulation of the auricular branch of the vagus nerve, where individuals from early HF stages (FC I and II) may respond by upregulating members of the HSP family, and that metabolic exhaustion present in hearts from FC III and IV patients may explain the lack of HSP60 activity.146