Diagnosis

To diagnose supraventricular tachycardia, your doctor will ask questions about your symptoms and your medical history and perform a physical exam. Blood tests are usually done to check for other health conditions that could cause your symptoms, such as thyroid disease.

Your doctor may also order several tests to check your heart health. Tests to diagnosis SVT include:

• Electrocardiogram (ECG). During an ECG, sensors (electrodes) that can detect the electrical activity of your heart are attached to your chest and sometimes to your limbs. An ECG measures the timing and duration of each electrical phase in your heartbeat.
• Holter monitor. This portable ECG device can be worn for a day or more to record your heart's activity as you go about your routine.
• Event monitor or mobile telemetry device. For sporadic episodes of SVT, you may be asked to wear an ECG device for a longer period of time (up to 30 days or until you have an SVT episode or arrhythmia or typical symptoms).
• Echocardiogram. In this noninvasive test, a hand-held device (transducer) placed on your chest uses sound waves to produce images of your heart's size, structure and motion.
• Implantable loop recorder. This device detects abnormal heart rhythms and is implanted under the skin in the chest area.

If your doctor doesn't find a heart rhythm problem during those tests, you may need other tests, such as:

• Stress test. For some people, supraventricular tachycardia is triggered or worsened by stress or exercise. During a stress test, you'll be asked to exercise on a treadmill or stationary bicycle while your heart activity is monitored. If you can't exercise and your doctor thinks heart disease may be causing your arrhythmia, you may receive a drug to stimulate your heart in a way that's similar to exercise.
• Tilt table test. Your doctor may recommend this test if you've had fainting spells. Your heart rate and blood pressure are monitored as you lie flat on a table. The table is then tilted as if you were standing up. Your doctor observes how your heart and the nervous system that controls it respond to the change in angle.

• Electrophysiological testing and mapping. In this test, doctors thread thin tubes (catheters) tipped with electrodes through your blood vessels to several areas within your heart. Once in place, the electrodes can map the spread of electrical signals through your heart.

  In addition, your cardiologist can use the electrodes to stimulate your heart to beat at rates that may trigger — or stop — the arrhythmia. This test allows your doctor to see the location of the arrhythmia and what may be causing it.