CABG is performed in patients with significant narrowing of one or more coronary arteries to relieve angina, prevent myocardial infarction and sudden cardiac death. CABG improves the flow of blood to the area of myocardium affected by a coronary artery stenosis by >50%. During surgery a healthy blood vessel is taken from the leg, forearm or chest and grafted to the diseased coronary artery to create an alternative route for the blood flow around the atherosclerotic blockage. Either veins or arteries may be used as conduits for CABG. The most commonly used blood vessels are saphenous veins and the internal thoracic (mammary) artery (Figure 38.1).

Valve surgery is performed to repair or replace diseased heart valves and is often combined with CABG. Valve regurgitation and stenosis are the most common problems requiring surgical intervention. Regurgitation results when the valve doesn’t close tightly causing blood to leak back through the valve. Stenosis occurs when a valve doesn’t open fully due to calcium deposits or scarring (Figure 38.2). Repair is common for mitral and tricuspid valves, while the aortic valve is usually replaced (Figure 38.3). Aortic stenosis, due to age-related progressive calcification is the most frequent type of heart valve disease in older adults, necessitating valve replacement.

Two types of replacement valve are used: