What does it mean that the imperial doctor Xilaile failed to clear his heart?

Finally, Xilaile treated Dr. Wang Taiyi with lamp oil.

Dr. Wang Taiyi, a doctor of medicine in TV series, has held a grudge against Xilaile since it cured Wang's illness. When Xilaile was recommended by Wang as a cure-too-doctor, and was appreciated by the Empress Dowager Cixi Lafayette, Dr. Wang Taiyi regarded Xilaile as a thorn in the side and wanted to get rid of it quickly. Wang Dong seized every opportunity to suppress Xilaile during his death, and Xilaile was almost destroyed by Dr. Wang, and his family wealth was exhausted. When Dr. Wang was seriously ill and dying, Xilaile put aside personal grievances and came to Dr. Wang's bed with the goodwill of the doctor. It happened that Dr. Wang was blocked with phlegm, and Xilaile wrung the paper flat with lamp oil.