Coronary artery bypass graft (CABG) surgery reroutes blood flow around blocked coronary arteries by using transplanted blood vessels to create detours for blood to flow past blockages and deliver oxygen to the heart muscle. CABG is advised for patients with significant narrowing or blockages of the heart arteries from coronary artery disease. Heart valve surgery repairs or replaces diseased valves and is used to treat valve narrowing, leaking, defects from birth, infections, or calcium deposits. An implantable cardioverter defibrillator (ICD) is an electronic device implanted in the chest that monitors the heart rhythm and delivers electrical pulses or shocks to restore normal heart rhythms when fast or abnormal rhythms are detected.