Almost 2.3 million people in the UK are living heart disease and >36,000 cardiac surgery operations are carried out each year. During surgery the heart is isolated from the rest of the circulation and a heart-lung machine is used to supply oxygen to the blood and pump it around the body. The heart is stopped and provided with nutrients by a cardioplegic solution that is injected directly into the heart arteries. This allows the surgeon to operate on the heart while it is still and not filled with blood but looking after the heart in this way during surgery is not ideal. The heart muscle can become short of oxygen, and when the heart is restarted, and blood starts to flow again the muscle can be harmed.
The damage is believed to be caused mainly by the formation of highly reactive molecules known as ‘free radicals’ in the heart muscle during the time it is short of oxygen. Propofol is a general anaesthetic widely used in cardiac surgery and research suggests that propofol could protect the heart muscle against damage from free radicals. We want to investigate whether adding propofol to the cardioplegic solution in patients having isolated coronary artery bypass grafting (CABG) surgery using the heart-lung machine is beneficial and if the benefit is greater the more propofol that is used.