CONTRAINDICATIONS TO EXERCISE TESTING AND PRESCRIPTION

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CONTRAINDICATIONS TO EXERCISE TESTING AND PRESCRIPTION

No matter what kind of exercise testing or physical conditioning is in order, the first step of the clinical evaluation is to determine if any contraindications to exercise exist. Contraindications to exercise must be continually evaluated. Some contraindications can be determined from a simple medical history or physical examination. Others require further laboratory procedures and perhaps, even stress testing to determine. Even after all the testing has been competed, contraindications for exercise training can still manifest.
Contraindications to exercise are not specific to the clinical environment.
The three main purposes for exercise testing are

• Diagnostic and/or Prognostic
• Therapeutic
• Prescriptive
  

The purpose of diagnostic/prognostic exercise testing is to provoke certain conditions or disease so that it can be found and evaluated. The exercise test is more aggressive with larger work increments. The end point of the test is the detection of disease. The recovery is also designed to stress the heart more. The patient is usually put into the supine position to see how the heart responds to an increased venous return caused by the position.
Therapeutic exercise tests are designed to evaluate medical and surgical intervention and are similar to the diagnostic tests. In this case, a condition has been diagnosed for a patient and the patient has been either put on medication to control a condition or has undergone a surgical procedure to correct a problem. The purpose of this test is to see how effective the intervention was. For example, a patient presents to the physician with chest pain. The physician uses the diagnostic tests to determine the presence of angina and then prescribes medications to control the discomfort. The physician then performs another exercise test, the evaluation test, to determine if the medications can effectively control the angina.
On the other hand, the prescriptive test is to determine the functional capacity of the individual and to see how the heart rate and blood pressure respond to the work so that a safe and effective exercise prescription can be given. The test protocol is less aggressive with smaller work increments and an active recovery. The end-point of the test is usually 85% of heart rate max or a maximal voluntary effort.
Prior to any type of exercise testing, the contraindications must be determined based on the purpose of the test and the testing environment. What appears to be contraindications to exercise testing in one setting may not be in another. Although standards of practice should be taken into consideration, the medical director of the program is ultimately responsible for determining contraindications for that site.
The following contraindications were presented by the American College of Sports Medicine. These have been divided into two categories, Absolute and Relative.

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Absolute Contraindications

A recent significant change in the resting ECG suggesting infarction or other acute cardiac events. Exercise testing in the presence of suspected infarction or other unknown cardiac events can further compromise the condition. For example, a silent infarct which has not been previously evaluated may reinfarct and cause more cardiac damage during exercise. These ECG changes should be referred to the physician to be evaluated before exercise testing can proceed.

In a prescriptive setting, these ECG changes are absolute contraindications. However, these ECG changes may be an indication for diagnostic/prognostic exercise testing as part of the evaluation process. Later, after medical or surgical intervention, exercise testing may be appropriate to evaluate the efficacy of the intervention.
Recent complicated myocardial infarction. A recent complicated infarct may become more compromised by exercise. However, low-level discharge exercise tests are frequently administered to uncomplicated infarct patients. In such cases, the enzymes and ECG changes must be stabilized prior to testing.
Unstable angina. Unstable angina is a recent change in anginal patterns. More than half of the post MI patients who survive the MI report that the nature or pattern of their angina changed before the infarct. The typical interval was approximately seven days. Therefore, changing anginal patterns indicates a worsening of the disease and probable infarct.
Uncontrolled ventricular dysrhythmia. Typical ventricular dysrhythmia include frequent PVCs, either unifocal or multifocal, couplets, and Ventricular tachycardia. These dysrhythmia compromise cardiac function because the abnormal beat often produces little or no stroke volume. Cardiac output may be decrease at rest and may not increase with exercise.
On the other hand, some ventricular dysrhythmia are diagnosed by exercise testing especially if they can not be provoked during a 24 hour Holter Monitor. In addition, the medications used to control the ventricular dysrhythmia may be evaluated by exercise testing.
Uncontrolled atrial dysrhythmia that compromises cardiac function. Common atrial dysrhythmia include atrial flutter, atrial fibrillation, and paroxysmal atrial tachycardia. In these dysrhythmia, the atria may not be contracting normally. The contribution of the atrial kick to the cardiac output may be absent. In addition, the ventricles may not get the signal from the atria to contract at a rate appropriate for exercise. Cardiac output may not increase with exercise in the presence of these rhythms.
On the other hand, diagnostic/prognostic exercise testing may used to evaluate the dysrhythmia and exercise testing to evaluate medical intervention may be used following administrations of medications.
Third degree A-V Block. A third degree heart block is a complete heart block or a complete dissociation between the beating of the atria and the ventricles. The atria and the ventricles are contracting at their own rate and the atria do not communicate the impulse to beat to the ventricles. The atria usually contract faster at a rate of 70 to 80 per minute; and ventricles usually contract around 30 per minute. This has also been called an idioventricular rhythm.
The slow ventricular rate is associated with a reduced cardiac output and therefore compromised blood flow. There are two types of complete heart block, congenital and acquired. These types are summarized in the table below. Acquired heart block is associated with 1) coronary heart disease, 2) hypertension, and 3) aortic valvular disease.
Exercise testing can be use to determine the efficacy and evaluation of the pacemaker.
Acute congestive heart failure. Congestive heart failure is a circulatory insufficiency resulting from a variety of etiologies. The heart is in congestive heart failure when it is unable to maintain stroke volume. Excess fluid blacks up into the ventricle, the atria and eventually the pulmonary system. Pulmonary edema as well as edema of the extremities results. Pulmonary edema leads to a cough and shortness of breath which can be detected at rest or during exercise. Cardiac output is compromised at rest in congestive heart failure. Exercise exacerbates the condition.
Patients with congestive heart failure can will often have exercise testing for prognostic evaluation. In addition, the efficacy of medications may also be evaluated through exercise testing.
Severe aortic stenosis. Aortic stenosis is a narrowing of the aortic valve. The narrowing presents an increased resistance to blood flow, an increased afterload, and increased work of the heart.
The work of the heart is compromised at rest in severe aortic stenosis. In addition, the blood flow to the coronary arteries is decreased because of increased ventricular pressures. Exercise further increases the work and subsequent demand for coronary blood supply. Ischemia, infarct, dysrhythmia, and loss of consciousness (via decreased cerebral blood flow) can result with exercise in severe aortic stenosis.
Mild cases of aortic stenosis can tolerate exercise well. In some cases, a patient with aortic stenosis will undergo a prognostic exercise test to determine if exercise is appropriate.
Suspected or known dissecting aneurysm. A dissecting aneurysm is a weakening of the vessel wall which causes a ballooning between the intimal and medial layers of the vessel wall. Atherosclerosis and hypertension are contributing factors. Because the ballooning is susceptible to rupture, the higher blood pressures of exercise must be avoided.
Active or suspected myocarditis or pericarditis. Myocarditis is an inflammation of the cardiac muscle tissue which can be associated with many types of infection. Pericarditis is an inflammation of the pericardial sac surrounding the heart and can result from many different causes from trauma to infarction. The treatment for both conditions is bed rest.
Thrombophlebitis or intracardiac thrombi. Thrombophlebitis is an inflammation and clotting of a vein and intracardiac thrombus is a clot in the chambers of the heart. Exercise is contraindicated because the higher blood flow and pressures during exercise can dislodge the clot. The typical recovery time for thrombophlebitis is 4 to 6 weeks during which time anticoagulants are administered.
Recent systemic or pulmonary embolus. An embolus is a clot or substance in the blood stream. A pulmonary embolus is in the pulmonary circulation whereas a systemic embolus is found in the rest of the circulation. Similar to thrombophlebitis, the higher pressures and flow during exercise may move the embolus to a vital area and cause infarct.

Acute infection.

Significant emotional distress (psychosis).

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Relative Contraindications

Resting diastolic blood pressure >120 mm Hg or resting systolic blood pressure >200 mm Hg. Elevated pressures may reflect other conditions which may require further medical attention. Each blood pressure should be compared to previous pressures.
Moderate valvular heart disease. Rheumatic valvular disease, aortic regurgitation, mitral valve prolapse, and tricuspid disease are examples of moderate valvular disease. Rheumatic valvular disease is an alteration of the structure of the valve resulting from previous rheumatic fever. Regurgitation and poor opening are the major manifestations. The most common valves involved in rheumatic valvular disease are the aortic or mitral. Occasionally the tricuspid valve will be involved, however, the pulmonary valve is almost never involved.
The most common valvular disease found in women is mitral valve prolapse which is a falling down or dropping down of the mitral valve. Mitral regurgitation and frequent dysrhythmia are symptoms of mitral valve prolapse. A 2% mortality, more specifically sudden death during exercise exists.
Known electrolyte abnormalities (hypokalemia, hypomagnesemia). Hypokalemia, low potassium, and hypomagnesemia, low magnesium, increase the risk of exercise testing. In both cases, toxic responses, characterized by ventricular dysrhythmia, can be provoked by exercise. Diuretic medication for hypertension can lead to hypokalemia. Hypokalemia not only provokes dysrhythmia, but blunts the ST segment response making the ST segments uninterpretable.
Fixed-rate pacemaker. A fixed rate pacemaker improves the chronotropic action of the heart, but does not allow variation in the heart rate. In cases of exercise, where cardiac output increases via heart rate and stroke volume, a patient with a fixed-rate pacemaker will be unable to increase cardiac output adequately.
Exercise testing has also been used to evaluate dysrhythmia associated with exercise in the pacemaker patient.
Frequent or complex ventricular ectopy. Ventricular ectopy includes PVCs, either unifocal or multifocal, couplets, and short runs of V tach. Because ectopic beats are often associated with reduced ejection fraction, frequent and complex ectopy can compromise cardiac output, especially during exercise. Blood pressures should be monitored closely to insure adequate ventricular performance during exercise testing for individuals presenting with ventricular ectopy.

In addition, recent onset of ectopy may result in ventricular irritability secondary to an infarct. A probable infarct should be referred for evaluation prior to exercise testing.
Other indications of increased ectopy may include excess caffeine intake, mitral valve prolapse, digitalis toxicity, or any other type of condition that may require further evaluation before testing.
Ventricular aneurysm. A ventricular aneurysm is a ballooning of the ventricle associated with a massive myocardial infarction. Common locations of aneurysms are the anterior wall and the apex.
Because ventricular aneurysms are usually associated with hypertrophy, ventricular dysrhythmia, and congestive heart failure, caution must be taken in exercise testing and training.
Cardiomyopathy, including hypertrophic cardiomyopathy. Cardiomyopathy is a disease or abnormal condition of the cardiac muscle. Cardiomegaly is a hypertrophy of the heart, often of unknown origin.
Idiopathic Hypertrophic Subaortic Stenosis (IHSS) is a congenital condition characterized by enormous hypertrophy of the ventricle, usually the septum. Because the hypertrophy of the septum provides resistance to the blood flow, the hemodynamics are similar that found in aortic stenosis. In addition, these patients have a high risk of sudden death during exercise.
Uncontrolled metabolic disease. Metabolic diseases include diabetes, thyrotoxicosis, and myxedema. Chapter Eleven discusses Diabetes in detail. Both thyrotoxicosis and myxedema are associated with the thyroid gland. Thyrotoxicosis is a toxic condition due to a hypertrophy of the thyroid gland. It is associated with a rapid heart action. On the other hand, myxedema results from hypofunction of the thyroid gland and is characterized by anemia and mental apathy.
Chronic infectious disease
Neuromuscular, musculoskeletal, or rheumatoid disorders that are exacerbated by exercise.
Advanced or complicated pregnancy. Toxemia of pregnancy is a condition that affects some pregnant women later in gestation. It is characterized by an increased fluid retention which increases both the work of the heart and blood pressure. As a consequence, uterine blood flow is decreased and could be decreased more with exercise.
Heart disease in pregnancy has also been shown to decrease uterine blood flow during exercise in humans (Morris).

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The first essential aspect of exercise testing is to determine the existence of these relative and absolute contraindications to exercise. Each contraindication must be evaluated in terms of the purpose of the exercise evaluation and the setting.

Information regarding the contraindications can be obtained from the medical history and physical examination as well as the laboratory testing itself.

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