原级：cardiologist
1. He was also examined by cardiologists and his heart was found healthy with normal functioning.
2. There are both too many and too few coronary stent implants operations in China, one of the country's top cardiologists claims.
3. Cardiologists first spent more than three hours to transfer a healthy heart.
4. A long debate has simmered over whether the heart's cells are replaced and most cardiologists had been convinced that they were not.