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By the end of this course, the learner will be able to:
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Overview: A typical patient with angina is 50-60 year-old male or a 65 to 75-year old woman. The Framingham Study, a long term study started in 1949 consisting of 5127 men and women who since have been examined at two-year intervals to determine factors relating to the development of heart disease, has determined that one in four men with angina can expect to have a myocardial infarction within 5 years; that for women the risk is about half that for men; and that the 8-year mortality rate in patients with angina who are over 55 is about 30%, of which about 44% of the deaths will be sudden. Angina is estimated to effect 7,120,000 people in the United States and 350,000 new cases of angina occur each year. The estimated crude prevalence of angina: for non-Hispanic white women is 4.1%, for men is 3.4%; for non-Hispanic black women 4.6%, and men 2.6%; for Mexican-American women 4.6% and men 3.4%.
Stable Angina Pectoris The patient usually describes stable angina pectoris symptoms in one or several of the following terms: heaviness, pressure, squeezing, and sensation of strangling or constriction in the chest. It may also be described as aching, burning or indigestion. The pain typically occurs in the substernal region of the chest and may radiate to the neck, jaw, teeth, arms shoulders and abdomen. The more severe the attach the greater the radiation. The pain usually is of short duration. Angina pectoris is a condition in which the heart muscle does not receive enough blood (nutrients and oxygen) resulting in chest pain. This lack of blood supply to the heart muscle to sustain various levels of work required of the heart is called myocardial ischemia. Coronary atherosclerosis is often an underlying problem in angina. Angina occurs when the blood flow to the heart is enough for normal needs but not enough for increased needs such as occurs in physical exercise, strong emotions or extreme temperatures. For example running to catch a bus could trigger an attack of angina where walking to the bus stop might not. People who have coronary artery spasm may have angina when they are resting. This is called Prinzmetal's or variant angina pectoris. Variant Angina or Prinzmetal's Angina Variant angina also called Prinzmetal's angina differs from typical chronic stable angina pectoris in that it occurs almost exclusively when a person is at rest and does not follow a period of physical exertion or emotional stress. Attacks can be very painful and usually occur between midnight and 8 a.m. Many people with Prinzmetal's angina go through an acute, active phase. Anginal and cardiac events may occur frequently for six months or more. During this time, nonfatal myocardial infarction occurs in up to 20% of patients and death occurs in up to 10% of patients. People who develop arrhythmia (heart rhythm irregularities) at this time are at greater risk for sudden death. Most people who survive this initial three to six-month period stabilize and their symptoms and cardiac events diminish over time. Their long-term survival ranges from 89 to 97% at five years. Unstable Angina Pectoris Unstable angina pectoris is a clinical syndrome with symptoms between stable angina pectoris and acute myocardial infarction and perhaps sudden death. Unstable angina appears in three different ways: A patient with chronic stable angina experiences progressive increase in frequency, and pain severity with less exertion or at rest. A patient without angina history may experience angina, which is unstable, progressive in frequency and severity with less and less exertion. A patient has prolonged coronary pain that is clinically suggestive of acute myocardial infarction without ECG or enzymatic evidence of infarction. This can occur in patients with or without previous stable angina. Patients with unstable angina should be hospitalized immediately for both therapy and diagnosis. The following are some of the conditions that can have clinical symptoms similar to angina pectoris: Myocardial Infarction, Pericarditis, right ventricular hypertension, aortic stenosis, and esophageal spasm. Therefore, a differential diagnosis between angina and other conditions is made when such symptoms occur. Tests for Angina
The standard electrocardiogram (ECG) is a critical tool in the diagnosis of angina pectoris. In fact a 12-lead ECG recorded at rest in the
absence of pain is normal in about half of the patients with typical angina. However, an ECG taken in the presence of pain may yield a
great deal more information because it may document the presence of transient ST segments depression, a characteristic sign of
subendocardial ischemia.
An exercise ECG is helpful in detecting coronary artery disease in patients with a normal resting ECG. It requires progressive, upright supervised exercise, usually on a treadmill to achieve 85% of the patient's maximal heart rate. Several studies have correlated findings from the exercise ECG with the presence or absence of significant obstruction of the coronary arteries with findings with angiography. In general, the studies show that an exercise ECG has a sensitivity of about 65% and a specificity of about 90%. This means that patients without coronary artery disease will have a negative test 90% of the time or that the false-positive rate is 10%. Variant angina is due to coronary artery spasm. In approximately 75% of the patients severe atherosclerotic coronary artery obstruction is present in at least one major vessel. The spasm usually occurs very close to the obstruction. The ergonovine test is the most sensitive test for coronary artery spasm. Ergonovine is introduced to induce coronary spasm. Hyperventilation and coronary injections of acetylcholine are other means used to induce variant angina. Radioisotope imaging is a viable procedure for diagnosing coronary artery disease. Presently thallium-201 is the isotope most frequently used for myocardial imaging. Angiography is the procedure that provides the most information about the coronary arteries; it carries risks that include myocardial infarction, stroke, and death. Mortality is about 0.1% in centers that perform a minimum of 6 procedures a week. The risk for infarction and stroke are also about 0.1%. A clear indication for angiography is a patient with unacceptable incapacitating angina who is on maximal medical therapy or in young and vigorous patients who have a great deal of cardiac muscle at ischemic risk. Medical Therapy Angina can be treated medically with drugs which purpose is to reduce myocardial oxygen consumption, improve coronary artery blood flow and prevent disease progression. The physiological factors most favorable to manipulation are blood pressure, heart rate, contractility and left ventricular volume. Progression of atherosclerotic disease can be slowed by control of lipids (fats), smoking cessation, regular exercise and use of drugs such as aspirin to help prevent thrombosis from plaque rupture and platelet plugs. Postmenopausal estrogen replacement may be helpful in women at risk for cardiovascular disease. Medical therapy for ischemia is generally the combined use of beta-adrenergic blocking agents, nitrates, and calcium channel blockers. Beta-adrenergic blocking agents such as propranolol reduce heart rate, myocardial contractility and blood pressure. Part of the hypotensive effect is a result of vasodilation. Nadolol, timolol, pindolol and labetalol are also nonselective beta-blockers. Metroprolol, atenolol, acebutolol and betaxolol are cardioselective blocking agents. Nitrates by their action reduce myocardial oxygen consumption and can also increase coronary artery blood flow and are platelet inhibitors. Depending on the situation, nitroglycerin can be administered sublingually (beneath the tongue) by skin patch, intravenously, or orally by tablet. Calcium channel blockers play a key role in the electrical excitation of cardiac cells and in the mechanical contraction of both myocardial and vascular smooth muscle cells. Nifedipine, nicardipine, felodipine, amlodipine, isradipine and bepridil are calcium channel blockers that are available for use in the United States. These agents differ in mode of action and clinical effect. However, they are all effective for the treatment of coronary artery spasm via the influx of calcium into vascular smooth muscle cells. They are also effective for the treatment of both chronic stable angina and unstable angina pectoris. The combination therapy of beta-blocking agents and nitrates are used to control pulse rate and blood pressure. The addition of calcium blockers can further relieve angina symptoms in 60 to 70 percent of patients. The dosages of these drugs in combination are carefully determined and monitored to achieve effective medical treatment. Anticoagulation therapy with warfarin in the treatment of angina is controversial. There are no convincing studies showing that anticoagulation therapy reduces angina. Many randomized clinical trials have shown that antiplatelet agents (such as aspirin) play a secondary role in the prevention of cardiovascular events in patients who have had a stroke, transient ischemia, myocardial infarction, or unstable angina.
Invasive Procedures Percutaneous transluminal coronary angioplasty (PTCA) is an accepted, viable therapy for some patients with coronary artery disease. This procedure requires that a balloon-tipped catheter is passed percutaneously and is maneuvered across an area of stenosis in a coronary artery. The balloon is then inflated under pressure which causes dilation of the artery in the area of stenosis (narrowing of the artery). The National Heart, Lung and Blood Institute has a registry of PTCA patients and has found that the overall success rate has risen from 67% between (1977-1981) to 88% between (1985-1986). The current PTCA mortality rate is about 1%. About 4 % of PTCA patients have complications such as prolonged angina or myocardial infarction, which requires emergency coronary artery bypass surgery. In 30 to 40% of patients stenosis recurs in the effected PTCA artery. PTCA is mostly used in single-vessel disease, but in certain cases can be done in multi-vessel disease. Coronary artery bypass surgery (CABG) generally involves one of two procedures. A saphenous vein is taken from the thigh and used to bypass the obstructed coronary artery. The distal end of the vein is sutured to the aorta and the proximal end into the coronary artery beyond the stenotic area. The internal mammary artery is freed and its distal end is anastomosed (connected with sutures) to the coronary artery beyond the occlusion. With an experienced cardiovascular operating team CABG has a mortality rate of 1 to 2%. Complete relief of angina is about 70% and another 20% have partial relief. Sixty-five to 85% experience increased exercise tolerance. In general studies have shown that the greater the severity of coronary artery disease and left ventricular dysfunction, the greater the benefit of surgery over medical therapy. Thus, surgery improves survival in patients with main left coronary artery disease and in patients with three-vessel disease plus impaired left ventricular function. No study has demonstrated that surgery improves survival for one or two-vessel disease without involvement of the proximal left anterior descending artery. The decision on whether or not to adopt a medical or surgical approach for a patient with angina is directly related to the amount of myocardium (heart muscle) at risk from a single occlusive event.
References Scientific American Medicine, July, 1997, 1:IX Ischemic Heart Disease: Angina Pectoris, (CD-ROM) Isselbacher K, Braunwald E, Wilson J, Fauchi A, Kasper D, Eds: Harrison's Principles of Internal Medicine, 13th Edition, McGraw-Hill, New York, 1994, (CD-ROM) American Heart Association, Heart & Stroke A-Z Guide, World Wide Web Internet site, URL: http://www.amhrt.org Antianginal Agents: Organonitrates, Calcium Channel Blockers, Beta-Adrenergic Antagonists, URL: http://lysine.pharm.utah.edu/netpharm/dl_ang.htm Angina and Acute Myocardial Infarction, Internet URL: http://home.hkstar.com/-shwan/angina_AMI.html U.S. National Library of Medicine , Health Services/Technology Assessment Text data (HSTAT) data base, Internet URL: http://text.nlm.nih.gov/ Landau C, Lange RA, Hillis LD: Percutaneous transluminal angioplasty. New England Journal of Medicine 318:265, 1988 Hampton JR, Henderson RA, Julian DG, et al: Coronary angioplasty versus coronary artery bypass surgery: the Randomized Intervention Treatment of Angina (RITA) trial. Lancet 341:573, 1993 Hamm CW, Reimers J, Ischinger T, et al: A randomized study of coronary agioplasty compared with bypass surgery in patients with symptomatic multivessel coronary disease. New England Journal of Medicine 331:1037, 1994 Franklin BA, Exercise and Angina. Physician and Sportsmedicine, 1995 Jul;23(7):79-80 MEDCEU Continuing Education Courses CEU for Nurses and Healthcare Professional
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