PSVT stands for paroxysmal supraventricular tachycardia, a type of abnormally fast heart rhythm that starts suddenly, lasts minutes to hours, and then stops just as abruptly. During an episode, the heart races at 120 to 230 beats per minute, well above the normal resting rate of 60 to 100. The word “paroxysmal” means it comes and goes in episodes, “supraventricular” means the problem originates above the heart’s lower chambers, and “tachycardia” simply means a fast heartbeat.
How PSVT Works Inside the Heart
Your heart relies on electrical signals that travel along a specific path to coordinate each beat. In PSVT, those signals get caught in a loop. Instead of firing once and moving on, the electrical impulse circles back on itself, triggering the heart to beat again immediately. This creates a rapid, repetitive rhythm that can sustain itself for seconds, minutes, or occasionally hours before the loop breaks and normal rhythm returns.
The three main types of PSVT are defined by where that electrical loop forms. The most common is AVNRT (atrioventricular nodal reentrant tachycardia), where the loop exists within the heart’s central electrical junction. The second is AVRT (atrioventricular reentrant tachycardia), where an extra electrical pathway between the upper and lower chambers creates the circuit. The third and least common type is focal atrial tachycardia, where a single spot in the upper chambers fires electrical signals too rapidly. All three produce the same hallmark pattern: a heart that suddenly shifts from a normal rate to a very fast, regular rhythm, then snaps back to normal.
What an Episode Feels Like
Palpitations are the defining symptom, reported by about 84% of people during an episode. You feel your heart pounding, fluttering, or racing in your chest, and it typically starts without any warning. Nearly half of people also experience chest pain, and about 38% feel short of breath. Lightheadedness, sweating, and fainting are also common. Some people describe a sensation of fullness or pounding in the neck, caused by the upper chambers of the heart contracting against closed valves.
About 94% of people say their episodes seem to come out of nowhere. A smaller number, around 15%, notice emotional stress just before an episode begins, and about 17% link the onset to a specific body movement like bending over, crouching, or lying down.
What happens after an episode is sometimes overlooked but worth knowing about. More than half of people report fatigue and lightheadedness once normal rhythm returns. About 45% notice they urinate more frequently than usual in the one to three hours following an episode. This happens because the rapid heart rate stretches the heart’s upper chambers, which triggers the release of a hormone that signals the kidneys to produce more urine. A small percentage, around 7%, experience lingering chest pain for one to three hours afterward.
How PSVT Is Diagnosed
The challenge with PSVT is that episodes are unpredictable. Your heart may be beating perfectly normally during a routine office visit, so a standard electrocardiogram (ECG) might look completely unremarkable. The most reliable diagnosis comes from capturing the heart’s electrical activity during an actual episode. Portable heart monitors worn for days or weeks can catch those fleeting events.
When an ECG does capture an episode, doctors look for specific clues to determine which type of PSVT is present. A fast, regular rhythm with a narrow waveform on the tracing points toward a supraventricular origin. Subtle distortions in the waveform can reveal whether the loop is running through the heart’s central junction (suggesting AVNRT) or through an accessory pathway (suggesting AVRT). These distinctions matter because they guide treatment decisions, particularly if a procedure to correct the problem is being considered.
Stopping an Episode
The first line of defense during an episode is a set of physical techniques called vagal maneuvers. These work by stimulating the vagus nerve, which slows electrical conduction through the heart and can break the reentrant loop. The most well-known technique is the Valsalva maneuver: bearing down hard as if straining during a bowel movement. In its standard form, this works only about 5% to 20% of the time.
A modified version has proven far more effective. You perform the same bearing-down effort while sitting up at a 45-degree angle, then immediately lie flat and have your legs raised to 45 degrees. A large analysis of 19 clinical trials involving over 2,500 patients found that this modified approach roughly doubled the success rate compared to the standard technique, with no increase in side effects. The overall success rate in the modified group was significantly higher, making it the recommended first step during an episode.
If vagal maneuvers don’t work, the next step in a medical setting is a medication given through an IV that very briefly (for a few seconds) blocks electrical conduction through the heart’s central junction. This pause is usually enough to interrupt the loop and restore normal rhythm. The sensation can feel intense, with a brief flush of warmth or chest tightness, but it passes within seconds.
Long-Term Treatment Options
For people who have infrequent, brief episodes that aren’t too disruptive, learning vagal maneuvers and managing triggers may be enough. Avoiding known triggers like excessive caffeine, alcohol, sleep deprivation, and high stress can reduce how often episodes occur.
When episodes are frequent or significantly affect quality of life, catheter ablation is the most definitive treatment. In this procedure, a thin wire is threaded through a blood vessel to the heart, and the small area of tissue responsible for the abnormal electrical loop is carefully destroyed using heat or cold energy. The long-term success rates are high: 98% for AVNRT (the most common type) and 92% for AVRT. For focal atrial tachycardia, the success rate is around 80%. These numbers make ablation one of the most effective procedures in cardiology, and most people who undergo it never have another episode.
Daily medications to prevent episodes are another option, typically reserved for people who prefer not to have a procedure or who aren’t good candidates for ablation. These drugs work by slowing the heart’s electrical conduction, making it harder for the reentrant loop to sustain itself.
Is PSVT Dangerous?
PSVT is rarely life-threatening. The heart itself is usually structurally normal, and the episodes, while frightening, don’t cause lasting damage in most cases. The main concern is quality of life: unpredictable racing heartbeats can cause significant anxiety, limit physical activity, and lead to repeated emergency room visits. Fainting during an episode can also be dangerous depending on what you’re doing at the time, such as driving or climbing stairs. In rare cases involving very prolonged or extremely fast episodes, the heart muscle can weaken over time if the condition goes untreated, a phenomenon known as tachycardia-induced cardiomyopathy. For the vast majority of people with PSVT, effective treatment eliminates episodes entirely or reduces them to a manageable level.