The Nuclear Medicine (NM) Lexiscan Stress Test evaluates heart health by assessing blood flow to the heart muscle, both at rest and under simulated stress. It provides insights into the heart’s function.
Purpose and Overview of the NM Lexiscan Stress Test
The NM Lexiscan Stress Test, also known as a pharmacologic or chemical stress test, assesses the condition of the heart’s coronary arteries. This test is useful for individuals who cannot perform physical exercise due to limitations like arthritis. Instead of physical exertion, Lexiscan (regadenoson) simulates exercise effects on the heart.
Nuclear medicine procedures use small amounts of radiotracers to create images of internal structures and functions. In this test, Technetium-99m sestamibi is a common radiotracer that distributes in the heart muscle proportional to blood flow. Lexiscan works by widening coronary arteries, increasing blood flow to the heart muscle. This helps identify areas not receiving sufficient oxygen. The test aids in diagnosing or monitoring coronary artery disease (CAD), where narrowed or blocked arteries reduce heart blood flow.
Before Your Test: Preparation Guidelines
Preparation for an NM Lexiscan Stress Test involves specific instructions for accurate results. Avoid all caffeine-containing products for 12 to 24 hours before the test, including coffee (even decaffeinated), tea, soda, chocolate, and certain over-the-counter medications. Caffeine interferes with Lexiscan’s effectiveness, potentially leading to inaccurate outcomes.
Fast for 3 to 6 hours before the test, though water is permissible. Discuss all current medications with your healthcare provider, as some heart medications like beta-blockers or those containing dipyridamole or theophylline may need adjustment. Wear comfortable, loose-fitting clothing and bring necessary documents, such as a medication list.
During the Test: The Lexiscan Procedure
Upon arrival, you will register and change into a hospital gown. A healthcare professional will place an intravenous (IV) line, usually in your arm or hand, for administering medications and tracers. Electrodes will be attached to your chest to monitor heart activity.
The initial part involves baseline, or “rest,” imaging. A small amount of radiotracer, such as Technetium-99m sestamibi, is injected through the IV. After a short waiting period, you will lie still while a special camera takes heart images. Lexiscan is then administered rapidly through the IV, typically over about 10 seconds.
Patients often experience temporary sensations shortly after the Lexiscan injection, which might include flushing, warmth, headache, chest discomfort, or shortness of breath. These effects typically begin quickly and usually subside within 15 minutes, though headaches may last slightly longer. A second dose of the radiotracer is injected shortly after Lexiscan to capture “stress” images. The entire procedure, including waiting periods and imaging, generally takes approximately 2 to 4 hours.
After the Test: Recovery and Understanding Results
After the imaging is complete, the IV line will be removed, and you will be monitored briefly to ensure any lingering effects from the Lexiscan have subsided. Drinking fluids is often encouraged to help flush the radiotracer from your system. Any temporary side effects from Lexiscan, such as headache or flushing, should resolve relatively quickly. If concerns arise or symptoms persist, it is important to contact your healthcare provider.
The images captured during the test are analyzed by a cardiologist or nuclear medicine physician. Results are typically not immediate, as the images require careful interpretation. A normal test result indicates that blood flows adequately to all areas of your heart muscle during both rest and simulated stress.
If the test is abnormal, it may suggest areas of reduced blood flow, blockages, or ischemia, which means the heart muscle is not receiving enough oxygen. Sometimes, results might be inconclusive, potentially requiring further diagnostic evaluations. Your doctor will discuss the findings with you and recommend appropriate next steps, which could involve lifestyle adjustments, medication changes, or additional diagnostic procedures like angiography, depending on the findings.