conte , who has performed about about 200 heart and lung transplantations on humans , said that , after dr. alexis carrel , an american surgeon and experimental biologist who won a 1912 nobel prize for his work in organ transplantation and in other fields , demikhov `` probably had the biggest early impact on the field of heart and lung transplantation , because during the '40s and '50s he did hundreds and hundreds of experiments on dogs that showed different techniques of how to actually do heart and lung transplants .