I do not remember the title, it is a novel about 30-40 years old by a popular writer.
The story is that a Jewish doctor is called to treat the Pope who has a heart problem and in the first 20 pages or so follows a full and complete description about the treatment and how the Pope will feel and react following the procedure.
This sounds like “Lazarus,” the third Vatican book by Morris West, a mid-20th century writer who wrote many popular novels, including a lot with Catholic themes.
from Kirkus review:
His Holiness Leo XIV–the aged, iron-willed, unsmiling Pope from a peasant background–is about to be opened up for bypass surgery. His superb Jewish heart surgeon warns him that being so near death will bring on a profound psychological change, perhaps long-lasting depression, and a general weakening of mental powers for at least three months.