The heart condition SVT, supraventricular tachycardia, is a periodic, very fast heartbeat that is not created by exercise, stress or high fever, according to WebMD. SVT is caused by a problem in the heart's electrical system that results in a heartbeat ranging from 100 to 300 beats per minute.
SVT episodes typically only last a short period of time, WebMD reports. With treatment, and sometimes on its own, the heart returns to a normal rhythm of 60 to 100 beats a minute. Some patients have episodes that occur so quickly that they don't report symptoms. SVT becomes serious when episodes last for longer periods.
Although malfunctioning electrical connections in the heart are the most common cause of SVT, it can be brought on by other factors, WebMD states. Medications, including some prescribed for heart and lung problems, can cause SVT. Sometimes the condition runs in families, such as those who develop Wolff-Parkinson-White syndrome. Occasionally other health issues and even surgery can cause SVT.
SVT symptoms include feeling dizzy or light-headed, WebMD explains. Some patients experience a pounding pulse or a feeling that the heart is racing. Other symptoms include fainting or near-fainting, throat tightness, shortness of breath, chest tightness and sweating.