Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Myocardial Infarction, Acute


Related Terms

  • Acute Coronary Syndrome (ACS)
  • Angina
  • Cardiovascular Disease
  • Coronary
  • Coronary Artery Disease
  • Coronary Occlusion
  • Coronary Thrombosis
  • Heart Attack
  • Ischemic Heart Disease
  • MI

Differential Diagnosis

Specialists

  • Cardiologist, Cardiovascular Physician
  • Cardiothoracic Surgeon
  • Critical Care Internist
  • Emergency Medicine Physician

Comorbid Conditions

Factors Influencing Duration

Factors that may lengthen disability include extent of the MI, development of complications, the individual’s age, and co-existing medical conditions. The length of disability may also be affected by physical demands of the job. Individuals with larger infarcts (greater loss of exercise capacity due to greater loss of heart pumping ability) and individuals with more strenuous jobs may lack the capacity to return to prior employment.

Medical Codes

ICD-9-CM:
410.00 - Myocardial Infarction of Anterolateral Wall, Episode of Care Unspecified
410.01 - Myocardial Infarction of Anterolateral Wall, Initial Episode of Care
410.02 - Myocardial Infarction of Anterolateral Wall, Subsequent Episode of Care
410.10 - Myocardial Infarction of Other Anterior Wall, Episode of Care Unspecified
410.11 - Myocardial Infarction of Other Anterior Wall, Initial Episode of Care
410.12 - Myocardial Infarction of Other Anterior Wall, Subsequent Episode of Care
410.20 - Myocardial Infarction of Inferolateral Wall, Episode of Care Unspecified
410.21 - Myocardial Infarction of Inferolateral Wall, Initial Episode of Care
410.22 - Myocardial Infarction of Inferolateral Wall, Subsequent Episode of Care
410.30 - Myocardial Infarction of Inferoposterior Wall, Episode of Care Unspecified
410.31 - Myocardial Infarction of Inferoposterior Wall, Initial Episode of Care
410.32 - Myocardial Infarction of Inferoposterior Wall, Subsequent Episode of Care
410.40 - Myocardial Infarction of Other Inferior Wall, Episode of Care Unspecified
410.41 - Myocardial Infarction of Other Inferior Wall, Initial Episode of Care
410.42 - Myocardial Infarction of Other Inferior Wall, Subsequent Episode of Care
410.50 - Myocardial Infarction of Other Lateral Wall, Episode of Care Unspecified
410.51 - Myocardial Infarction of Other Lateral Wall, Initial Episode of Care
410.52 - Myocardial Infarction of Other Lateral Wall, Subsequent Episode of Care
410.60 - Myocardial Infarction of True Posterior Wall, Episode of Care Unspecified
410.61 - Myocardial Infarction of True Posterior Wall, Initial Episode of Care
410.62 - Myocardial Infarction of True Posterior Wall, Subsequent Episode of Care
410.70 - Subendocardial Infarction, Episode of Care Unspecified
410.71 - Subendocardial Infarction, Initial Episode of Care
410.72 - Subendocardial Infarction, Subsequent Episode of Care
410.80 - Myocardial Infarction of Other Specified Sites, Episode of Care Unspecified
410.81 - Myocardial Infarction of Other Specified Sites, Initial Episode of Care
410.82 - Myocardial Infarction of Other Specified Sites, Subsequent Episode of Care
410.90 - Myocardial Infarction of Unspecified Site, Episode of Care Unspecified
410.91 - Myocardial Infarction of Unspecified Site, Initial Episode of Care
410.92 - Myocardial Infarction of Unspecified Site, Subsequent Episode of Care

Overview

© Reed Group
Myocardial infarction (MI) is widely known as a heart attack. It results in permanent damage to a portion of the heart wall due to decreased blood flow (ischemia) and thus oxygen delivery. In about 90% of cases, MI is caused by the formation of a blood clot (thrombus) that obstructs an artery that brings blood to the heart (coronary artery). Rupture of an area of cholesterol build-up (plaque) that has accumulated within a coronary artery over time (atherosclerosis) is often the trigger for thrombus formation. MI may be preceded by pain in the chest (angina). Other non-atherogenic causes of MI include vasospasm (e.g., variant angina); drug use that can lead to coronary vasospasm (i.e., methamphetamines, cocaine); small masses (emboli) that obstruct a coronary artery (e.g., from an infected cardiac valve); severe chest trauma from a motor vehicle accident; or coronary occlusion from vasculitis. Less common causes include situations that cause a mismatch between the demand for oxygen and the available supply, leading to cardiac ischemia and MI. Some examples include acute anemia (e.g., from a gastrointestinal bleed) and carbon monoxide poisoning.

Incidence and Prevalence: In the US, about 1.5 million MIs per year result in 500,000 to 700,000 deaths (Zafari). An MI occurs every 29 seconds, with one death each minute. In the US, incidence of MI is 600 per 100,000 individuals per year (Zafari). Incidence of MI in developed countries is similar to the US with the exception of France and the Mediterranean region where the incidence is lower; some researchers believe that this is due to a diet rich in monounsaturated fats and wine consumption with meals. Cardiovascular disease is the leading cause of death worldwide, causing 12 million deaths per year (Zafari).

Source: Medical Disability Advisor



Causation and Known Risk Factors

Risk factors for atherosclerotic plaque formation which cannot be modified include age over 60 (plaques take time to develop), male gender, and family history. Risk factors that can be modified include obesity, smoking, diabetes mellitus, elevated lipid levels (hypercholesterolemia, hypertriglyceridemia), uncontrolled hypertension, and sedentary lifestyle.

Among individuals between 40 and 70 years of age, more men than women will have atherosclerosis and Mis; risk for men and women becomes equal after age 70. (Zafari). Although MI is most common in individuals older than age 45 years, the risk in younger individuals increases for cocaine users, insulin-dependent diabetics, those with hypercholesterolemia, smokers, and those with a positive family history of atherosclerosis. Those with a first-degree male relative younger than 45 years of age with MI, or with a first-degree female relative younger than 55 years of age with MI also have a heightened risk (Zafari).

Source: Medical Disability Advisor



Diagnosis

History: Most myocardial infarctions produce severe anterior chest pain that lasts for over 15 minutes, or much longer than the usual (3-10 minutes for episodes of angina without infarction). MI can be "silent" or go unrecognized, especially in diabetics. There is usually a history of risk factors including prior cardiac history, diabetes mellitus, elevated lipid levels (i.e., hypercholesterolemia and hypertriglyceridemia), uncontrolled hypertension, smoking, and sedentary lifestyle, as well as family history. The circumstances surrounding onset should be delineated; time since onset is especially important since chest discomfort that lasts longer than 30 minutes suggests MI. Pain accompanying MI is often localized in the anterior chest and may be described as tightness, pressure, heaviness, or a squeezing sensation. Pain may radiate into the arm (more commonly the left arm), neck, jaw, or stomach area. Shortness of breath (dyspnea) may be present, and may be the only symptom of MI in diabetics and the elderly. There may also be cough and wheezing. Nausea with or without vomiting and abdominal pain may be present, particularly with inferior or posterior wall involvement. The individual may be lightheaded with or without loss of consciousness (syncope), anxious, sweaty (diaphoretic), weak, or fatigued. It is especially important to consider the diagnosis of MI in individuals who are more likely to have atypical presentations including diabetics, the elderly, and women.

Physical exam: On physical examination, the individual may be lying quietly in bed and appear pale and sweaty. Heart rate may be increased (tachycardia), normal, or decreased, and the pulse may be irregular due to dysrhythmias. Additional sounds not heard in a healthy heart may also be present (third and / or fourth heart sounds). Blood pressure may be increased (hypertension), normal, or decreased (hypotension). Some individuals may have a low-grade fever. If congestive heart failure (CHF) is present, there may be abnormal lung sounds (rales), swelling in the lower extremities (edema), and distention of the neck veins (elevated jugular venous pressure).

Tests: Commonly ordered blood tests include a complete blood count (CBC) to exclude anemia and infection; serial cardiac enzymes (troponin, creatine kinase, and creatine kinase-MB) to follow damage to heart muscle over time; serum electrolyte levels; and C-reactive protein (CRP), a marker of inflammation. In normal people the cardiac enzyme levels in the blood are very low, but, if heart muscle dies (infarcts), the dying heart cells release these chemicals and they are then present at increased levels in the blood. An electrocardiogram (ECG) may show changes in the electrical patterns of the heart and can help to localize the damaged area. However, only about half of all individuals with MI will show changes on their ECG. Those with definite changes are called "ST segment elevation myocardial infarcts" (STEMI), while those with proven infarctions but who lack these definite EKG changes are called "NON-ST segment elevation myocardial infarcts" (NSTEMI).

Imaging studies can help to rule out alternative diagnoses or complications as well as localize the damaged area of heart muscle. Chest x-ray can reveal pulmonary edema resulting from heart failure. Echocardiography is helpful in evaluating wall motion abnormalities and ventricular function and also can show complications from an MI such as valvular insufficiency or pericardial effusion. Transesophageal echocardiography is used to distinguish MI from aortic dissection. Radioisotope scans reveal areas of healthy tissue and are especially helpful in individuals with an atypical presentation. High-resolution CT scans allow direct visualization of the interior (lumen) of coronary arteries as well as any plaque in the coronary walls. The definitive imaging study is cardiac catheterization, that shows the location of the artery blocked typically by a blood clot, and the residual degree of heart pumping ability (ejection fraction). It also detects many potential cardiac complications.

Source: Medical Disability Advisor



Treatment

The goal of treatment is to restore adequate blood flow (perfusion) and oxygen supply to the heart, relieve pain, and prevent or treat any complications. More than half of all deaths from MI occur in a pre-hospital setting (Zafari). Appropriate pre-hospital treatment by trained emergency medical services (EMS) personnel is key to improving the chance of survival. An extension of this is bystander use of automated external defibrillators. Most individuals will receive (either during ambulance transport to the hospital or on their arrival in the emergency department) aspirin, a beta-blocker to help control heart rate and thereby reduce oxygen demand, and morphine sulfate for control of pain and anxiety. When appropriate, nitrates may be given to help reduce discomfort, lower blood pressure, and relieve pulmonary congestion.

The best treatment for myocardial infarction is immediate cardiac catheterization and revascularization of the heart by angioplasty / stent / atherectomy. In this procedure, a tiny flexible tube (catheter) with a balloon at the tip is inserted into the femoral artery in the groin. The catheter is advanced through the artery to the site of the blockage in the coronary artery and the balloon is inflated. This opens the artery; sometimes a metal stent is placed to help the artery to stay open.

If the coronary anatomy cannot be adequately “fixed” by an angioplasty / stent, emergent coronary artery bypass grafting may be indicated.

For those who are not able to be quickly treated in a hospital with cardiac catherization capability, intravenous medication to dissolve the blood clot that is blocking the coronary artery (thrombolytic therapy) may be an option if the person is treated within the first few hours after onset of the infarction. This medication is administered into an arm vein (intravenously).

Some individuals do not present to a hospital until a few days into their heart attack, and some have contraindications to cardiac catheterization (e.g., patients with known severe renal disease who cannot tolerate the x-ray contrast agent needed to visualize coronary anatomy or patients in cardiogenic shock) Thus, some are not treated with immediate catheterization, but rather are managed “medically”.

Once stable, the individual will be transferred to the cardiac care unit (CCU) for continual heart monitoring and observation. Other medications that are used in specific situations include angiotensin converting enzyme (ACE) inhibitors, platelet glycoprotein Iib/IIIa inhibitors, anti-arrhythmic drugs for irregular heart rhythms, medications to increase or decrease blood pressure, diuretics to increase urine output and remove excess fluid from the lungs (e. g., CHF, pulmonary edema). These and other medications that were started in the hospital are usually continued at the time of discharge. If the blood cholesterol level is above 200 mg/dL, medication to lower cholesterol may be prescribed.

Source: Medical Disability Advisor



Prognosis

Early recognition of signs and symptoms associated with MI can significantly reduce mortality and improve prognosis. Involvement of trained emergency medical services (EMS) personnel in pre-hospital care can shorten the interval between onset of symptoms and definitive care. More than 50% of deaths occur before the individual reaches the hospital (Zafari). Once hospitalized, the mortality rate is 10% (Zafari). Survivors have a reduced life expectancy due to progression of the coronary artery disease and the effects of the same disease process (atherosclerosis) in other vascular beds (e.g. stroke).

In those treated medically (without revascularization) a low-level treadmill stress test may be done just before discharge to help assess long-term prognosis, need for medication(s) to treat exertional chest pain (exertional angina), or need for further procedures to improve blood flow to the MI damaged area of the heart (revascularization procedures). These procedures include balloon angioplasty, placement of stents, and coronary bypass surgery. The treadmill study can be a factor in return-to-work decisions.

Source: Medical Disability Advisor



Rehabilitation

Cardiac rehabilitation can be very helpful in recovery from MI. Individuals who have experienced an MI progress through an individualized, graded exercise program to increase their exercise tolerance and fitness levels.

Phase 1 often begins in the hospital and uses low levels of exercise to prevent problems associated with prolonged bed rest, decrease the likelihood of blood pressure fluctuations that can occur with changes in position (orthostatic hypotension), and maintain mobility. Exercises begin with the individual lying on his or her back (supine position) and progress to exercises performed in a sitting and later, a standing position. A gradual increase in the distance an individual is able to walk is an important part of the individual's exercise program. Initial sessions with a physical therapist may be 5 to 10 minutes, with a gradual increase in the duration and physical demands.

Phase 2 begins after discharge from the hospital and takes place in an outpatient setting such as a rehabilitation center. Goals are to improve functional capacity by increasing physical endurance and promoting return to everyday activities. Individuals undergo electrocardiograph (ECG) monitoring while performing exercise. A physical therapist keeps a daily log of the individual's blood pressure, heart rate, and cardiac rhythm.

Phase 3, also in an outpatient setting, begins 3 to 6 months from the start of rehabilitation and may last for several months. Individuals may continue an outpatient program for up to a year to accomplish their goals while remaining on modified work duty. The level of exercise is gradually increased to include recreational activities such as swimming, hiking, cycling, and light jogging according to the individual's tolerance. Modifications may need to be made for individuals who have had surgery or who have other medical conditions.

Cardiac rehabilitation should combine progressive exercise with education and lifestyle modification. It is essential to change exercise, diet, stress management, smoking, and lifestyle habits to decrease the risk of a recurring MI.

FREQUENCY OF REHABILITATION VISITS
Nonsurgical and Surgical
SpecialistMyocardial Infarction, Acute
Physical TherapistUp to 2-3 visits/week within 4 months, or 36 total visits
For those who have had a heart attack within the last year, Medicare covers up to 36 sessions (http://www.caring.com/medicare_information/medicare-coverage-of-cardiac-rehabilitation).

Source: Medical Disability Advisor



Complications

There are several uncommon, but very serious mechanical complications of MI. These include rupture of a valve, rupture of the wall between the two pumping chambers (ventricular septal defect), and rupture of the wall of the heart (cardiac rupture). These are medical emergencies and require urgent surgery. Many are fatal. Most of these have occurred, and thus are known before the person has recovered enough for return to work decisions to be discussed.

Another complication is recurrent or persistent chest pain (angina). Persistent chest pain for several days after an MI is common and may be due to inflammation of the surface of the heart (pericarditis) or inadequate oxygen supply to the heart (ischemia).

Another complication is Heart Failure (HF). This happens when damage to the heart muscle prevents adequate pumping action, leading to a decrease in blood flow to the tissues and organs of the body. Symptoms include shortness of breath, fatigue, and swelling in the ankles and feet. This may be a temporary condition with recovery of the heart muscle in a few days or weeks, or it may signal permanent damage. New York Heart Association Functional Class III (comfortable at rest, but symptoms of CHF with almost any activity) is usually compatible only with sedentary work. New York Heart Association Functional Class IV (symptoms at rest) is usually not compatible with gainful employment, and consideration of heart transplantation is the potential treatment.

Arrhythmias may occur after an MI. Some arrhythmias (e.g., premature ventricular contractions (PVCs)) are so common that they are considered part of the MI rather than a complication. A slow heart beat (bradycardia) is less common than some of the other arrhythmias and may require the insertion of an electronic pacemaker. Having had a prior MI does predispose to having future arrhythmias, including episodes of syncope (loss of consciousness) and cardiac arrest (sudden cardiac death). If the patient has had serious arrhythmias during the hospitalization and / or early convalescent period, or if the infarct was large and the heart's pumping ability (ejection fraction) is severely reduced, the person may be treated with an implanted cardiac defibrillator. This battery powered device is about the size of a pacemaker, but is designed to detect arrhythmias with fast heart rates that could produce syncope or cardiac arrest, and terminate the arrhythmia by giving the heart an electronic shock (cardioversion).

Re-stenosis of coronary arteries treated by angioplasty / stent / atherectomy does occur. Most of these occur early (3-6 months after the infarct/percutaneous procedure). For this reason an exercise treadmill test is frequently done between 3-6 months after the infarct and percutaneous procedure to detect this before a recurrent infarction occurs.

Long term progression of the underlying coronary artery disease frequently occurs, and to prevent this as well as to prevent disease in other arteries (e.g. stroke) secondary prevention by treating modifiable risk factors (including cholesterol level, blood pressure, smoking, sedentary life style, and diabetes) is important.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Individuals with an uncomplicated small MI, a normal, or near normal, ejection fraction, good results on a low-level treadmill test (good exercise capacity and no angina/ischemia), and whose work is not strenuous, usually can return to full-time work without restrictions within 2 to 4 weeks.

Individuals with work involving more strenuous activity or who have developed complications such as CHF, usually require additional time for recuperation before returning to work. The larger the infarct, and the lower the ejection fraction, the greater the chances for serious ventricular arrhythmia and / or heart failure with heavy activity. Patients with low ejection fractions may have had prophylactic insertion of an implanted cardiac defibrillator. Reassignment to a less strenuous job may be necessary. Modifying risk factors such as obesity, smoking, hypertension, diabetes, elevated cholesterol levels, and sedentary lifestyle may help prevent future Mis (secondary prevention). Thus, exercise (including work) may build capacity and improve prognosis, but exercise may provoke serious arrhythmias and even cardiac arrest.

For more information on risk, refer the "Work Ability and Return to Work," page 262, and to "Disease and Injury Causation," page 238.

Source: Medical Disability Advisor



Maximum Medical Improvement

With no further evidence of unstable angina or significant arrhythmia, MMI would be at 180 days.

Source: Medical Disability Advisor



Failure to Recover

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:

  • Was diagnosis confirmed by ECG and serial cardiac enzyme tests?
  • What other tests were used to confirm the diagnosis and evaluate for complications?
  • X-rays? CT? Echocardiogram? Radioisotope scan?
  • Has a symptom limited treadmill test been done after the infarct to evaluate exercise (work) ability?
  • Is the level of exercise required for the individual’s job known from occupational tables? Is there a need to measure the exercise difficulty of the job in question?
  • Has an Echocardiogram been done to document the ejection fraction, and the competency of the cardiac valves?

Regarding treatment:

  • Did individual receive prompt treatment with a thrombolytic agent or undergo urgent coronary angioplasty? Was coronary artery bypass grafting performed?
  • Were appropriate medications administered?
  • Did the MI result in any complications?
  • Was a pacemaker or an implanted cardiac defibrillator inserted?
  • Were complications appropriately treated?
  • Is individual taking aspirin, a beta-blocker, an ACE inhibitor, and / or cholesterol-lowering drugs? Have other medications been prescribed?
  • Has the individual been in a formal cardiac rehabilitation exercise program? Is the individual doing a home aerobic exercise program?

Regarding prognosis:

  • Does individual have an underlying condition that may affect recovery? Is this condition(s) being effectively treated?
  • Is individual a candidate now for procedures such as balloon angioplasty, stents, or coronary bypass surgery?

Source: Medical Disability Advisor



References

Cited

Melhorn, J. Mark, and William Ackerman, eds. Disease and Injury Causation, Guides to the Evaluation of. AMA Press, 2008.

Talmage, J. B. , J. M. Melhorn, and M. H. Hyman, eds. Work Ability and Return to Work, AMA Guides to the Evaluation of. Second ed. Chicago: AMA Press, 2011.

Zafari, Maziar A. , et al. "Myocardial Infarction." eMedicine. 13 Dec. 2012. Medscape. 31 Jan. 2013 <http://emedicine.medscape.com/article/155919-overview>.

Source: Medical Disability Advisor






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