CD34 and hydrops fetalis: In addition, immunohistochemistry was used to assess the positive rate of CD34 and αSMA and the results showed that the positive expression rate of CD34 in myocardium tissues of the control and the HF group were 6.76 ± 0.58 and 17.13 ± 1.47% (p < 0.05), respectively (Figure 1D).