Claudio Vitale, 59, insisted on finishing the surgery in Naples before undergoing his own operation to clear an artery, Ansa news agency said.
Mr Vitale refused to abandon the operation to remove a tumour, even though he needed emergency treatment.
Both surgeon and patient are reported to be on the mend.
According to reports, Mr Vitale started to feel chest pains part way through the operation at Naples' Cardarelli Hospital.
When the pains worsened, Mr Vitale's team urged him to stop the procedure and get treatment, but he refused.
He agreed to undergo a blood test, which confirmed a heart problem, but the neurosurgeon insisted on completing the operation before getting medical help, reports say.
Half an hour after finishing the surgery, Mr Vitale had an angioplasty operation to treat an angina attack.
"I couldn't leave [the patient] at such a delicate moment," Mr Vitale was quoted by La Repubblica newspaper as saying.
"I'm not a hero, I only did my duty," he said.
Mr Vitale said he hoped to return to work after a period of recuperation.