Saijou no Meii

Saijou no Meii (最上の命医) is a manga written by Irie Kenzou and illustrated by Hashiguchi Takashi. It was serialized in Shounen Sunday and has a sequel by the name, Saijou no Meii: The King of Neet.

Plot
Saijou Mikoto was born with a bad heart. It was thanks to the incredible skills of Japanese leading pediatric heart surgeon, Shindou Mamoru, that he survived into adolescence, and he's decided to show his gratitude by becoming the greatest pediatric surgeon the world has ever known.