她决定专攻心脏病学，因为想要帮助更多心脏病患者。

She decided to specialize in ___cardiology because she wanted to help more patients with heart diseases.

他在医院的心脏科工作，专门研究心脏病学。

He works in the hospital's heart department, specializing in ___cardiology.

我父亲的心脏问题需要去看心脏病学专家。

My father's heart condition requires a visit to the ___cardiology specialist.