| Unstable angina is defined as a new onset of chest pain with exertion (effort angina) within the past 2 months, the increasing frequency or longer duration of pre-existing angina, or the precipitation of pre-existing effort angina with less exertion than previously used. Alternatively, it is defined as angina occurring at rest, usually longer than 20 minutes within the past week.
This condition represents a degree of hardening of the coronary arteries (coronary atherosclerosis) between that which characterizes stable effort angina and myocardial infarction (heart attack). Unstable angina is caused by temporarily inadequate oxygen delivery to a portion of the heart muscle (myocardial ischemia) due to either increased oxygen demand (as during exercise) or decreased oxygen supply (as during coronary artery spasm). Myocardial infarction involves a permanent loss of a portion of the heart's muscle cells. Not all individuals with unstable angina go on to infarction, although when infarction does occur, it is considered a serious development.Risk: Since unstable angina is an expression of coronary atherosclerosis, in general, risk factors for unstable angina are the same as those for atherosclerosis. |
Source: Medical Disability Advisor
| History: Pain in the center of the chest under the breastbone occurring at rest or with minimal exertion is typical. The individual reports a dull, heavy, or burning sensation, not a sharp one. Pain may radiate to the arms, neck, back, shoulders or jaw and can occur in only one of these regions without involving the chest. Physical exam: The exam during an episode of rest angina may reveal a change in the individual's blood pressure (hypertension or hypotension), disordered heart rhythm (gallop), a transient heart murmur, or skipped beats. Often, no abnormalities are present on physical exam. Tests: A 12-lead electrocardiogram (ECG) during pain at rest may show characteristic changes of the ST-T segments (ST segment elevation or depression, inverted T waves) but may occasionally be normal. A physical stress test such as a treadmill or a chemical stress test such as a dobutamine study may be performed if the chest pain does not recur or occurs infrequently during hospitalization. Coronary angiography is often indicated to define anatomy and refine the prognosis. Blood tests to measure the release of cardiac enzymes from damaged heart tissue may help confirm or exclude the diagnosis of myocardial infarction. Blood enzyme tests usually remain normal with unstable angina since actual damage to the heart is absent or minimal. These enzyme blood tests include CK-MB, troponin-T, troponin-I, CK-MB isoforms, and myoglobin. |
Source: Medical Disability Advisor
| Medical treatment for unstable angina includes nitroglycerin (NTG) administered under the tongue (sublingually), orally, or more often in a vein (intravenously). NTG preparations improve blood flow through the arteries nourishing the heart. NTG preparations also dilate arteries and veins in the arms, legs, and stomach (peripheral arteries and veins), thereby reducing the oxygen consumption of the heart. Medications that control high blood pressure (i.e., calcium channel blockers), lower the heart rate (i.e., beta-blockers), and control arrhythmias (i.e., digitalis, intravenous lidocaine, and miscellaneous oral anti-arrhythmics) are also very useful.
Aspirin therapy or other antiplatelet agents are often prescribed to retard or prevent the formation of a blood clot (thrombus) in the coronary artery and thereby reduce the chances of heart attack. Similarly, intravenous heparin is often initially employed to prevent thrombus formation and reduce the immediate chances of heart attack. Aspirin or other antiplatelet drugs may be continued indefinitely.
Initial treatment and management are based on the individual's risk of a heart attack or death while in the hospital. The risk is assessed at the time of admission. Individuals at low risk include those with rest pain lasting less than 20 minutes. Individuals at intermediate risk include those with chest pain at rest lasting longer than 20 minutes that is relieved by sublingual NTG and individuals with effort angina of less than 2 months duration or more than 2 months duration occurring with distinctly less provocation. Individuals at high-risk for heart attack include those with pain lasting more than 20 minutes that is unrelieved by NTG, marked ST-T wave changes during pain, and cardiovascular instability such as congestive heart failure and/or low blood pressure.
Individuals with low risk of unstable angina may be treated as outpatients. Individuals with new onset chest pain with effort are given a trial of antianginal medication starting with a sublingual nitrate for use during anginal attacks and an oral beta-blocker for ongoing use. If this does not control the symptoms, a long-acting nitrate may be added, either by mouth or as a skin patch or paste (topically). Calcium channel blockers are indicated for suspected coronary artery spasm (Prinzmetal's variant angina). An antiplatelet drug such as aspirin should be given to help reduce the possibility of a heart attack by inhibiting the development of a thrombus within the coronary artery.
Individuals with intermediate-risk unstable angina who manifest with increasing angina are usually already taking antianginal medications. These medications should be adjusted, as necessary, until the symptoms are controlled or until higher doses are not tolerated.
Individuals with new onset effort angina should have a cardiac stress test performed to define the risk of future cardiac events more accurately and plan further treatment. In most cases, a cardiac stress test is performed when the heart rate and blood pressure have been appropriately reduced with medication(s). A resting heart rate of 60 beats per minute or less and blood pressure of 120/80 or less are the usual goals. A treadmill study with or without a radioisotope (thallium) or a stress echo study using a drug called dobutamine are the two stress tests performed most often.
If a stress test shows ischemia despite the administration of medication(s), coronary arteriography is performed. It will indicate whether the blocked arteries can be successfully treated by a coronary revascularization procedure. Current revascularization procedures include balloon angioplasty, cleaning out the atherosclerotic material using a sharp device (rotational atherectomy), laser removal of atherosclerotic material, insertion of a device to mechanically "prop open" the coronary artery (intracoronary stent), and coronary artery bypass grafting (CABG) using veins from the legs or chest wall.
Individuals with intermediate-risk unstable angina are usually hospitalized and treated the same as low-risk individuals with unstable angina once they are pain-free. Individuals with ongoing pain at rest despite medication generally have coronary angiography performed to guide further therapy (i.e., more medication or a revascularization procedure). Those individuals who become pain-free with medical therapy alone usually have a cardiac stress test performed after being pain-free for 48 hours. The results are used to further assess risk and plan future treatment.
If the stress test does not produce angina or reveal ECG evidence of inadequate oxygen delivery to the heart muscle (myocardial ischemia), the individual is reclassified as low risk. Medical management is usually sufficient, and the individual may be discharged from the hospital 1 to 2 days after the stress test.
Individuals at high-risk usually have coronary angiography performed soon after admission, followed by a revascularization procedure. Individuals with ongoing symptoms and/or ischemia indicated by ECG are hospitalized and admitted to either a coronary care unit (CCU) or a monitored bed in a less intensive setting. An oral beta-blocker may also be prescribed. A cardiac stress test is performed after the individual has been pain-free for 48 hours. The results are used to reassess risk and plan further treatment. If the stress test does not reveal ischemia, the individual is reclassified as low risk. Medical management is usually sufficient, and the individual may be discharged from the hospital in 1 to 2 days.
If the stress test shows ischemia only during high levels of activity and if there is no evidence of left heart dysfunction (i.e., hypotension, difficulty breathing, or excessive fatigue), further diagnostic testing is required either by an alternative type of stress test or a coronary arteriography. If the stress test shows ischemia at low activity levels, or if there is evidence of left heart dysfunction, the individual is reclassified as high-risk. Coronary arteriography may be indicated, followed by revascularization.
High-risk unstable angina requires hospitalization and continuous ECG monitoring in a CCU. Initial treatment includes bed rest, oxygen, antiplatelet drugs, heparin, and antianginal medications. Sublingual nitrates are usually given first in addition to a beta-blocker. If the individual still has ischemia, a calcium channel blocker may be added if coronary artery spasm is suspected. In severe cases, narcotics may be necessary to relieve pain.
Symptoms continuing after an hour or more of medical treatment are an indication for immediate coronary arteriography followed by coronary bypass surgery or angioplasty. This treatment improves revascularization. If the individual's heart is failing seriously, intra-aortic balloon counterpulsation may be needed to support circulation until coronary bypass or angioplasty can be performed. However, most individuals can be stabilized with medical treatment. The individual is allowed to walk at increasing intervals if pain-free and stabilized for 24 hours. When symptoms are clearly under control, the individual is moved to a regular bed.
Further medical evaluation is the next step. Revascularization improves the prognosis in high-risk individuals, so coronary arteriography is performed usually within 24 hours to determine whether these procedures are feasible. After revascularization, ongoing treatment includes antiplatelet drugs and modification of risk factors. Anti-anginal drugs are not required unless residual ischemia occurs.
High-risk individuals who do not receive revascularization may require prolonged hospitalization. Individuals diagnosed with unstable angina receive the same ongoing treatment as prescribed for stable angina. These treatments include anti-anginal drugs, antiplatelet drugs, and modification of risk factors. |
Source: Medical Disability Advisor
| The outcome of unstable angina depends on several factors. One is the severity of the underlying coronary artery disease and whether it involves one, two, or all three of the coronary arteries. Prognosis also depends on the risk assessment of an acute myocardial infarction (AMI) on admission and on the type of treatment subsequently given. In many cases, revascularization by angioplasty, directional atherectomy, stenting, or CABG improves the prognosis. Unstable angina will either resume a stable course spontaneously or with therapy or progress to a heart attack. The unstable phase usually resolves within 8 weeks. If the individual survives the unstable phase, the prognosis becomes that of either stable angina pectoris or a myocardial infarction. |
Source: Medical Disability Advisor
| The goal of rehabilitation for unstable angina is to design a physical conditioning program for the individual that increases the amount of activity yet limits the onset of symptoms of this form of angina. Individuals must first be able to identify and communicate the symptoms as true angina pain. The physical therapist and other health care personnel knowledgeable in treating various forms of angina use a scale to rank anginal symptoms and determine the amount and intensity of exercise prescribed. Grading unstable angina on a pain scale of 1 to 9 ("1" being "no pain" and "9" being "unbearable") is a beneficial tool for individuals to communicate their angina symptoms during exercise to the physical therapist.
The exercise session for individuals with angina begins with a prolonged warm-up period. Proper breathing while exercising is critical. The principles of mild aerobic conditioning in a physical therapy setting have been commonly used in developing a program for individuals with various forms of angina including unstable angina. Rehabilitation for this condition follows the same progression in related cardiac diseases, with emphasis on avoiding fast bursts of activity and avoiding exertion.
Rehabilitation of the unstable angina patient begins with monitoring of symptoms throughout low-demand aerobic activities. In a hospital or cardiac rehabilitation setting, individuals are monitored for heart rate, rhythm, blood pressure, and chest pain. As endurance improves without symptoms of unstable angina, exercise time is advanced. Exercise increases in time and intensity as suits the individual. As the individual improves, work-type activities can be incorporated into the rehabilitation regimen to build the endurance needed for return to work.
This related increase in endurance also translates into a generally more active lifestyle. Ultimately, rehabilitation should enable the individual to perform endurance or aerobic routines such as running, brisk walking, cycling, or swimming, thus increasing the strength and efficiency of the heart. Modifications may be needed for those individuals taking various medications or who are experiencing other conditions with resulting angina. |
Source: Medical Disability Advisor
| The major complication of unstable angina is a myocardial infarction. Sudden death from a ventricular arrhythmia may occur. Additional complications arising from a myocardial infarction may also develop. |
Source: Medical Disability Advisor
| Activity is significantly limited during unstable angina. Restriction to no work or lighter and/or part-time work may be required after unstable angina has resolved, depending on the individual's functional classification following a treadmill or other stress test. Return to work for individuals who have an AMI or go on to CABG is based on the time needed to recover from the AMI or surgery. |
Source: Medical Disability Advisor
| If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case. Regarding diagnosis:
- Did individual present with any one of the clinical scenarios consistent with the diagnosis of unstable angina (new onset effort angina within the past 2 months, increasing frequency or longer duration of pre-existing effort angina, or precipitation of pre-existing effort angina with less exertion than previously used)?
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Did individual complain of dull, heavy, or burning pain in the chest that radiated to the arms, neck, back, or shoulders?
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Were there any abnormalities upon examination? Altered blood pressure, abnormal heart rhythm, or a heart murmur?
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Was a 12-lead ECG done? Did the findings indicate unstable angina?
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Was a coronary angiography performed, and did results support the diagnosis?
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Were blood tests taken to measure cardiac enzymes? Did results confirm or exclude diagnosis?
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If the diagnosis was uncertain, were other conditions with similar findings ruled out, i.e., coronary artery spasm, costochondritis, pulmonary embolism, pericarditis, or pleurisy?
Regarding treatment:
- Based on individual's risk for pending heart attack, was treatment prompt and appropriate? Was individual hospitalized?
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Was individual categorized as low, intermediate, or high-risk? Was pain relieved by sublingual NTG?
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Were anticoagulants, antiplatelets, or thrombolytic medications given? Was NTG prescribed? Were beta-blockers or calcium channel blockers necessary to slow the heart rate?
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Did individual's symptoms (chest pain) resolve within 1 to 2 hours after medical intervention? If not, was arteriography and angioplasty or coronary artery bypass done?
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Was the unstable angina associated with heart failure? If so, was intra-aortic balloon counterpulsation attempted to support the blood pressure and improve cardiac performance?
Regarding prognosis:
- Did the angina stabilize following medical interventions?
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Was angiographic or surgical revascularization done? If so, what was the expected outcome?
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Did individual participate in a cardiac rehabilitation program, as recommended? If not, are barriers present that prevent compliance with rehabilitation recommendations, i.e., insurance limitations, lack of transportation, or lack of motivation?
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Was the unstable angina complicated by a myocardial infarction?
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Does individual have any medical conditions that may affect ability to recover or influence prognosis (obesity, hypertension, diabetes mellitus, lung disease, heart valve disease, peripheral atherosclerosis, cardiomyopathy, or alcoholism)?
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Source: Medical Disability Advisor
| Cannon, Christopher P., and E. Braunwald. "Unstable Angina." Heart Disease: A Textbook of Cardiovascular Medicine. Eds. E. Braunwald, et al. 6th ed. Philadelphia: W.B. Saunders, 2001. 1232-1255. MD Consult. Elsevier, Inc. 19 May 2005 <http://home.mdconsult.com/das/book/47334204-2/view/924?sid=368472695>. |
Source: Medical Disability Advisor
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