A nuclear cardiology test in which blood flow to the heart muscle is evaluated under stress and at rest, used to detect ischemia caused by coronary artery narrowing.
Indication
- Investigation of ischemia in exertional chest pain or shortness of breath
- Evaluation of the extent and location of disease in known coronary artery disease
- Demonstration of residual ischemia after stenting or bypass
- Functional significance of intermediate stenoses found on angiography
- Cardiac risk assessment before high-risk surgery
- Need for additional evidence after equivocal ECG findings or exercise testing
Preparation
- Fasting for 4-6 hours before the test and avoiding caffeine-containing drinks (tea, coffee, cola) for 24 hours
- Adjustment of certain medications such as beta-blockers and calcium channel blockers with physician approval
- Reporting of asthma/COPD, advanced AV block, and recent cardiac event history (contraindications for dipyridamole)
- Comfortable exercise clothing and athletic shoes if pharmacologic stress is not needed
- Pregnancy or breastfeeding must be reported
How it's performed
- Intravenous access is established in the arm; ECG and blood pressure are continuously monitored
- In patients unable to exercise, dipyridamole (or a similar agent) is administered intravenously for pharmacologic stress
- During stress, a Tc-99m labeled radiopharmaceutical is injected intravenously
- After a specified waiting period, images of the heart muscle are obtained with a gamma camera
- Rest images are obtained on the same day or on a separate day
- Stress and rest images are compared to map ischemia or scar
Post-procedure
- Drinking plenty of water after the test helps eliminate the radiopharmaceutical faster
- Limiting close contact with infants and small children for the first 24 hours after the procedure is recommended
- Results are evaluated by a cardiologist; medical therapy or further investigation is planned
- If significant ischemia is detected, coronary angiography/intervention may be considered
- If results are normal, risk factor control and regular follow-up are continued
Risks
- The radiation dose is small and at a medical level; benefit is judged to outweigh the risk
- With dipyridamole/regadenoson administration: headache, chest tightness, flushing, mild hypotension
- Wheezing in asthma/COPD (reversed with aminophylline if needed)
- Very rare allergic reactions
- Arrhythmia or blood pressure changes with exercise
FAQ
Why is medication given during the test?
In patients unable to exercise, agents such as dipyridamole dilate the vessels to reveal the functional impact of any narrowing.
Why should I avoid tea and coffee before the test?
Caffeine reduces the effect of dipyridamole and may lead to a false negative result; at least 24 hours of caffeine restriction is recommended.
Is the radiation I receive harmful?
The amount used is at a low diagnostic dose; it is administered with a benefit-risk assessment when clinically indicated.
How long does the test take?
Total duration including stress and rest phases is usually 3-4 hours; some protocols may extend the test over two days.
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