Patient Education & Informed Consent
Patient Instructions
Provide patients with the following instructions:
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Do not eat, drink anything other than water, or smoke for 3 hours prior to the test.
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Do not consume anything with caffeine, including products that say “decaffeinated or “caffeine free,” after midnight the night before the test.
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Wear comfortable clothing.
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Bring a list of all current medications, along with times and dosages. (Before the test, consider each patient’s medications and withdraw those that will interfere with results prior to test if possible.)
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Avoid strenuous activities (eg, jogging, running) before the appointment.
Elements of Informed Consent
Patients are exposed to small amounts of radiation, and risks, while minimal, should be discussed.
Patients should be instructed regarding complications and complication rates for the relevant pharmacologic stress testing agents.
Equipment
IV pharmacologic stress testing requires a controlled delivery infusion pump.
A sphygmomanometer is used to record baseline blood pressure and repeat blood pressures during the test.
A 12-lead echocardiogram (ECG) is used for continuous monitoring.
Radioiodinated tracers are used to document stress testing results. Radioiodine (123I)-labeled agents are used to evaluate blood flow to the heart and left ventricular function.
Myocardial perfusion imaging (MPI) offers a method of visualizing blood flow to the heart by injection of a radioactive cardiac-specific tracer. This improves the diagnostic accuracy of a cardiovascular stress test by providing another method of detecting perfusion defects aside from measuring ST depression on the ECG. MPI offers the additional advantage of estimating left ventricular function.
Patient Preparation
Anesthesia
Anesthesia is not used in pharmacologic stress testing.
Positioning
Some centers prefer to use pharmacologic stress testing in conjunction with echocardiogram, MRI, or CT scanning because it avoids repositioning the patient, which may be necessary during nuclear imaging. Repositioning the patient may cause a false-positive pharmacologic stress test result because of different degrees of attenuation of myocardial tissue imaging with changes in the breast positions, as seen in women.
Monitoring/Follow-up
Continue monitoring (both electrocardiographically and hemodynamically) for at least 4 minutes after the effects of the pharmacologic stress testing agent have resolved.
Patients typically have no activity restrictions after the test.
Instruct breastfeeding women regarding when breastfeeding can be resumed, depending on the specific agent used.
Other follow-up may be required based on the results of the stress test or other related conditions.
Complications of Specific Agents
Specific pharmacologic agents have specific adverse effects, as follows:
Adenosine
Approximately 80% of patients experience minor adverse effects from adenosine infusion. However, an absence of these effects does not imply a lack of efficacy of the adenosine with respect to coronary vasodilation. The chest pain experienced during adenosine infusion is very nonspecific and does not indicate the presence of CAD. However, approximately a third of patients with ischemia after perfusion imaging have ST-segment depression during the infusion of adenosine.
Three categories of adverse effects exist, including systemic effects (dizziness [7%], headache [21%], symptomatic hypotension [3%], dyspnea [19%], and flushing [35%]), gastrointestinal effects (nausea [5.1%]), and cardiac effects (chest pain [34%] and ST-segment changes [13%]).
Dipyridamole (Persantine)
The adverse effects experienced are similar to those with use of adenosine. While adverse effects are less frequent with dipyridamole (47% of patients), they tend to be more serious than those associated with adenosine.
The most common adverse effects of dipyridamole are chest pain (19%), headache (12%), and hypotension (4.6%). In addition, 12% of patients require aminophylline for reversal of adverse effects.
Dobutamine
Adverse effects occur in approximately 75% of patients undergoing dobutamine stress testing. Effects include ST changes (50%), chest pain (31%), palpitations (29%), and significant supraventricular or ventricular arrhythmias (8-10%).
Regadenoson (Lexiscan)
During clinical development, of 1,337 patients in whom Lexiscan was administered, adverse effects occurred in 80% as follows: dyspnea (28%), headache (26%), flushing (16%), chest discomfort (13%), angina pectoris or ST-segment depression (12%), dizziness (8%), chest pain (7%), nausea (6%), abdominal discomfort (5%), dysgeusia (5%), feeling hot (5%).
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Normal radionuclide uptake (dipyridamole-Cardiolite).
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ECGs show a normal sinus rhythm and a sinus rhythm with a left bundle branch block.
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ECG depicts electrophysiologic events of left bundle branch block.
Tables
Results |
Rest |
Stress |
Conclusion |
Findings |
Normal |
Normal |
Blood flow to coronary artery is likely normal |
Findings |
Normal |
Reversible perfusion defect |
Artery blockage may be present |
Findings |
Abnormal |
Abnormal |
Heart has had prior injury, eg, previous heart attack |
