Both adult cardiac troponin I (cTnI; TNNI3 gene) and fetal/slow skeletal troponin I (ssTnI; TNNI1 gene) were expressed in the cardiac tissue of HF children, but only cTnI expression levels increased significantly by mechanical support compared to pre-VAD levels (Figure 4C). Here, TNNI1 is linked to hydrops fetalis.