Supraventricular Tachycardia
Supraventricular tachycardia (SVT) is an umbrella term for abnormal fast heart rhythms that start in the heart’s upper chambers or the conduction pathways above the ventricles. Episodes typically begin and end abruptly, with the heart suddenly racing at 150 to 250 beats per minute, then returning to normal just as quickly.
Key points
- This umbrella term covers fast heart rhythms starting above the ventricles, with episodes beginning and ending abruptly.
- An episode brings sudden chest pounding or fluttering, lightheadedness or breathlessness, and can last seconds or recur many times a week.
- Verapamil works by slowing the heart’s AV-node signalling, cutting off the re-entrant loop behind most episodes, and belongs among heart and blood pressure medicines.
What happens during an SVT episode
During an episode, most people feel a sudden pounding or fluttering in the chest, often accompanied by light-headedness, breathlessness, or mild chest discomfort. Some experience an urge to urinate as the rapid rate triggers hormonal changes. Episodes can last seconds or hours and may occur once in a lifetime or many times a week.
SVT is not usually life-threatening, but frequent or prolonged episodes can be exhausting and disruptive. When a doctor decides treatment is needed, verapamil is a well-established option: it works by slowing conduction through the atrioventricular node, terminating the re-entrant circuit that drives most SVT. It sits within the broader range of heart and blood pressure medicines used to manage cardiac rhythm and rate.
Seek urgent care if an episode lasts longer than 30 minutes, if you feel faint or lose consciousness, or if chest pain becomes severe.