After we take a thorough history (which indicates the cause and type of your syncope in the vast majority of cases), we may order the following tests, especially if we think your syncope is cardiac in origin:
- Electrocardiogram (ECG) – a number of electrical wires are placed on your torso, which transmit information about the electrical activity of your heart. This information is displayed as line tracings on paper, and can reveal abnormalities in the expected pattern of spikes and dips of the heartbeat
- Echocardiogram – A hand-held device is placed on your chest that uses high-frequency sound waves (ultrasound) to produce images of your heart's size, structure and motion. This provides valuable information about the health of your heart, and helps us gather information about the structure of the heart
- Holter/external loop monitoring – An external device (Holter monitoring is for 24 hours, while an external monitor provides up to 1 month of data) you wear that continually records the electrical activity of your heart during daily activities
- Electrophysiological test – This test is used to evaluate the integrity of the electrical system of the heart or to provoke arrhythmias suspected as the cause of syncope. First, we use both local and intravenous (IV) anesthesia, and then fine wires are threaded from the groin veins and positioned in strategic locations in the heart to record cardiac electrical signals and “map” the spread of electrical impulses during each heartbeat
- Exercise stress testing – You will be asked to walk in place on a treadmill with electrodes attached to your skin on the chest area to record your heart function. Many aspects of your heart function can be checked including heart rate, breathing, blood pressure, ECG (EKG) and how tired you become when exercising. This test has many uses, among them, helping diagnose the cause of syncope.
When the suspected cause of syncope is neurological (related to the nervous system) in origin, tests often include:
- Tilt table testing – This test is performed routinely at Valley. In it, you lie on a bed and are tilted to typically 60-70° while your heart rate and blood pressure are monitored. We use tilt table testing to distinguish between orthostatic hypotension and chronic orthostatic intolerance in cases of syncope we think may be related to a neural (autonomic function) disorder.
- Carotid sinus massage – This test can be performed alone or in conjunction with tilt-table testing. In it, one of our team manually presses on the carotid sinus artery, located in the side of your neck, to see if your syncope was produced by accidental stimulation of your carotid sinus (the large part of the arterial wall where the common carotid artery in the neck divides into its two main branches)
If the usual workup fails to reveal a cause, we may consider long-term continuous cardiac monitoring:
- An implantable loop recorder (ILR) is placed under the skin at the chest level in front of the heart. This monitoring device is considered the gold standard for diagnosing the cause of syncope when other tests have failed to do so. One of our team members places this small device near your left breastbone using a local anesthesia. You can go home the same day.
The device either automatically records the electrical activity of the heart when your heart rate drops below or goes above a specified threshold, or you can manually activate it when the feeling of dizziness or lightheadedness starts.
What we are seeking is the ECG recording at the time of your syncope. If that shows bradycardia, you may need permanent pacemaker implantation (PPM); if it shows supraventricular or ventricular tachycardia, you may need catheter ablation or ICD implantation.
