We use various other tests to evaluate and diagnose cardiac conditions, including the tilt table test and ankle brachial index (ABI).
Tilt Table Test
A tilt table test is used to evaluate the cause of unexplained fainting (syncope).
Your doctor may recommend a tilt table test if you’ve had repeated, unexplained episodes of fainting. A tilt table test may also be appropriate to investigate the cause of fainting if you’ve fainted only once, but another episode would put you at high risk of injury due to your work environment, medical history, age, or other factors.
A tilt table test is generally safe, and complications are rare. But, as with any medical procedure, it does carry a risk of complications.
Preparing for the test:
- You may be asked to not eat or drink 2 hours before the test
- Unless your doctor tells you otherwise, take your medications as usual
Potential complications include:
- Prolonged low blood pressure
- Prolonged pause between heartbeats (asystole)
- These complications usually go away when the table is returned to a horizontal position
In some cases, if blood pressure and heart rate changes indicate you are about to faint, the table is returned to a horizontal position, and you may not actually lose consciousness. If you faint at any time during the test while you’re in the vertical position, the table is returned to a horizontal position immediately, and you’re monitored closely. Most people regain consciousness almost immediately.
If you feel signs and symptoms such as nausea, sweating, light-headedness, or irregular heartbeats, tell a member of your healthcare team.
During the test:
- Sticky patches (electrodes) will be placed on your chest, legs, and arms. The electrodes are connected by wires to an electrocardiogram (ECG or EKG) machine that monitors your heart rate
- A blood blood pressure monitor will be placed on your arm or finger to check your blood pressure
- If needed, an IV line will be placed into a vein in your arm for delivering medication during the second part of the test
- You will lie down on a table that can be moved from a horizontal to a vertical position. The table has a footrest and safety belts. The belts are placed around your body during the test to help ensure that you don’t slip off the table
- Your heart rate and blood pressure are monitored for about five minutes while you’re lying flat (horizontal)
- The bed is then moved to a vertical position so that you are in a head-up position. Depending on the reason for the tilt table test, you may stay in the vertical position for about 5 to 10 minutes, or you may remain in the vertical position for up to 45 minutes. While you are in the vertical position, you remain as still as possible
- If you don’t faint or experience any other symptoms after 45 minutes, the medication isoproterenol may be given through an IV line. This medication lowers your diastolic blood pressure (the bottom number in a blood pressure reading), lowers peripheral vascular resistance, increases your heart rate, and may prompt the abnormal nervous system reflex that causes vasovagal or neurocardiogenic syncope. You will remain in the upright position and are monitored for another 15 to 20 minutes
When your tilt table test is complete, you may return to your normal activities for the remainder of the day.
Your CT images will be interpreted and a report of the findings will be sent to your physician, who will then discuss the results with you.
Ankle Brachial Index
Ankle brachial index (ABI) is a simple test to evaluate blood flow to your legs. This noninvasive test determines if there is any narrowing or restriction of an artery or blood vessel that reduces blood flow.
This test is done by measuring blood pressure at the ankle and in the arm while a person is at rest.
Preparing for the test:
- Wear comfortable, loose-fitting clothing
- Take your daily medication as normal
During the test:
- You will be asked to lie on your back while standard blood pressure cuffs are placed around your ankles and arms. The cuffs will be inflated and a small ultrasound probe will be placed against the leg. As the cuffs are deflated, waveforms will be documented, assessing blood flow.