What is Supraventricular tachycardia (SVT)?
Supraventricular Tachycardia (SVT) is an abnormal rhythm (arrhythmia) in which the top chambers of the heart (the atria) beat fast, often causing the bottom chambers of the heart (the ventricles) to beat faster than 100 beats per minute. SVT is actually a broad category that includes multiple different types of arrhythmias that share certain properties. During an episode of SVT, an individual's heart will often beat at a rate of over 100 beats per minute (bpm), although it is possible for the heart to be at over 200 bpm.
Although SVT is usually benign, it can be dangerous if a patient has such high heart rates that they develop symptoms of lightheadedness, shortness of breath, or loss of consciousness. This danger can be significantly increased if the patient experiences a loss of consciousness while operating a vehicle or heavy machinery, working at high elevations, working around a body of water, etc.
What causes SVT?
SVT is most frequently caused by abnormal circuits in the heart that allow the heart’s electrical activation to be conducted on pathways outside of the normal conduction system. Patients are often born with these abnormal circuits. For a majority of the time, these abnormal circuits are not in use. However, under the right conditions, these circuits activate and the SVT is started and may be maintained. SVT may also be caused by heart cells that beat autonomously from the heart’s normal conduction system and can be rapid enough to overpower the normal conduction system.
What are the symptoms?
Although some people with SVT have no symptoms, many patients will feel palpitations (an awareness of one's own heart beating), a feeling of a racing or pounding heart, lightheadedness, neck fullness, near-fainting, chest pain, shortness of breath, or loss of consciousness.
What is the treatment for SVT?
Medications can be helpful for SVT and may be the only treatment needed. When medications do not work or are not a good option, ablation procedures can also be pursued. In some SVTs, an ablation may actually be the preferred first line of treatment. Depending on the specific SVT that is determined to be present, an ablation may offer a definitive cure. For SVTs where an ablation is not curative, the procedure still is generally able to significantly decrease the frequency of the SVT and level of symptoms caused by the SVT. The best treatment choice will be determined after the specific type of SVT is diagnosed and after a discussion between you and the cardiologist as to the pros and cons of each approach.