Coronary bypass surgery is a procedure that restores blood flow to your heart muscle by diverting the flow of blood around a section of a blocked artery in your heart. Coronary bypass surgery is a surgical procedure that diverts the flow of blood around a section of a blocked or partially blocked artery in your heart. By creating a new pathway to the heart, coronary bypass surgery improves blood flow to your heart muscle. During coronary bypass surgery, a healthy blood vessel is taken from your leg, arm or chest and connected to the other arteries in your heart so that blood bypasses the diseased or blocked area.