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Irreversible ischemia : tissue necrosis ( myocardial scars).Seen in angina pectoris, left ventricular dysfunction, and/or heart failure.Partially or completely reversible when adequate oxygen supply is restored (e.g., after angioplasty or coronary artery bypass grafting ).Hibernating myocardium : a state in which myocardial tissue has persistently impaired contractility due to repetitive or persistent ischemia.Myocardial stunning: acutely ischemic myocardial segments with transiently impaired but completely reversible contractility.Reversible ischemia: Tissue is ischemic but not irreversibly dead and, therefore, still potentially salvageable.For example, a 50% reduction in radius results in a 16-fold increase in resistance: R ≈ 1/( 0.5 x r) 4 = 4 = ( 2/r) 4 = 16/r 4. Vascular stenosis increases vascular resistance significantly. Provided the length of the vessel and viscosity of blood remain constant, the degree of resistance can be calculated using the simplified formula: R ≈ 1/r 4.The resistance to blood flow within the coronary arteries is calculated using the Poiseuille equation : R = 8Lη/(πr 4), where R = resistance to flow, L = length of the vessel, η = viscosity of blood, and r = radius of the vessel.Effect of vascular stenosis on resistance to blood flow Rupture of an unstable atherosclerotic plaque (most common cause)Īn increased heart rate reduces oxygen supply and increases oxygen demand.Coronary atherosclerosis and sequelae, including:.Definition: mismatch between the amount of oxygen the myocardium receives and the amount it requires.Myocardial oxygen supply-demand mismatch CFR is reduced in individuals with CAD due to vascular stenosis and reduced vascular compliance.In healthy individuals, the CFR can be up to 4 times higher on exertion than at rest.Coronary flow reserve (CFR): the difference between maximum coronary blood flow and coronary flow at rest (a measure of the ability of the coronary capillaries to dilate and increase blood flow to the myocardium ).Severe ischemia results in myocardial infarction (see “ Acute coronary syndrome”).The extent of coronary stenosis determines the severity of the oxygen supply-demand mismatch and, thus, the severity of myocardial ischemia.Stable atherosclerotic plaque → vascular stenosis → increased resistance to blood flow in the coronary arteries → decreased myocardial blood flow → oxygen supply-demand mismatch → myocardial ischemia.For plaque formation, see “ Pathogenesis of atherosclerosis.”.Pathophysiology Plaque formation and coronary artery stenosis Atherosclerosis is the most common cause (see “ Risk factors for atherosclerosis”).Įpidemiological data refers to the US, unless otherwise specified. The lifetime risk of coronary artery disease at age 50 is approx.

CAD is the leading cause of death in the US and worldwide.Stable CAD: A form of CAD, in which patients are either asymptomatic or have stable or low-risk unstable angina also used for patients with a history of MI whose symptoms are controlled with treatment.Stable angina : a type of angina that occurs upon exertion, mental stress, and/or exposure to cold and usually subsides within 20 minutes of rest or after administration of nitroglycerin.Angina: chest pain caused by myocardial ischemia ( necrosis of myocytes has not yet occurred) due to narrowing (e.g., thrombus) or spasm (e.g., Prinzmetal angina) of the coronary artery.Coronary artery disease ( CAD): ischemic heart disease due to narrowing or blockage of coronary arteries, most commonly due to atherosclerosis, resulting in a mismatch between myocardial oxygen supply and demand.

Atherosclerosis and acute coronary syndrome (including MI) are discussed in separate articles. This article provides an overview of CAD as well as diagnostic and treatment options for patients with stable CAD. The management of stable CAD involves secondary prevention of atherosclerosis (e.g., smoking cessation, and treatment of diabetes mellitus, hypertension, and dyslipidemia), antiplatelet agents, antianginal medication (e.g., beta blockers), and, in severe cases, revascularization (e.g., percutaneous transluminal coronary angioplasty). Stable CAD can be diagnosed using cardiac stress testing, nonstress cardiac imaging, and/or coronary catheterization. Patients with stable CAD may have stable angina or be asymptomatic, while severe ischemia may lead to acute coronary syndrome, including myocardial infarction ( MI). Other symptoms include dyspnea, dizziness, anxiety, and nausea. Acute retrosternal chest pain ( angina) is the cardinal symptom of CAD. Coronary artery disease ( CAD) is a condition that is most commonly caused by atherosclerosis and the subsequent reduction in blood supply to the myocardium, resulting in a mismatch between myocardial oxygen supply and demand.