Cardiac surgery involves surgery on the heart or heart valves. A cardiac surgeon performs heart surgery, also known as coronary artery bypass surgery, on patients who have heart disease or heart valve disorders. Reasons that may make heart surgery necessary are: coronary artery disease, congenital heart defects, disease of the heart valves, or heart attack. Some heart conditions can cause permanent damage to the heart muscle, and can be fatal.

Doctor density varies by specialty and location. The United States has 113 practicing cardiac surgeons. Broken out by state, cardiac surgery doctor density in Alabama is 2, in Arizona is 3, in Arkansas is 4, in California is 33, in Colorado is 2, in Connecticut is 1, in Delaware is 1, in District of Columbia is 1, in Florida is 18, in Georgia is 6, in Hawaii is 1, in Illinois is 13, in Indiana is 3, in Iowa is 5, in Kansas is 1, in Kentucky is 6, in Louisiana is 5, in Maryland is 3, in Massachusetts is 6, in Michigan is 2, in Minnesota is 6, in Mississippi is 2, in Missouri is 9, in Montana is 2, in Nebraska is 3, in New Hampshire is 3, in New Jersey is 4, in New York is 7, in North Carolina is 3, in North Dakota is 1, in Ohio is 9, in Oklahoma is 1, in Oregon is 3, in Pennsylvania is 12, in South Carolina is 5, in Tennessee is 4, in Texas is 18, in Utah is 3, in Virginia is 2, in Washington is 3, in West Virginia is 5, and in Wisconsin is 5.