Fast heart rate (in paroxysmal supraventricular tachycardia)

If the heart beats very fast, it can often be felt as a racing heart or palpitations (pounding or fluttering) in the chest. In paroxysmal supraventricular tachycardia, the heart rate increases suddenly. It is usually between about 180 and 200 beats per minute during an episode. This can be uncomfortable and frightening.

You may also feel dizzy, weak, have chest pain and find it hard to breathe. In rarer cases, people faint (known as syncope) and fall. That's more common in older people. Some people have to pee a lot after an episode.

The fast heart rate in PSVT is usually caused by a problem in an area of the heart known as the AV node. The AV node lies between the atria (upper chambers) and ventricles (lower chambers).

Normally when the heart beats, the electrical signals coming from the upper chambers arrive at the AV node and are then passed on to the lower chambers. This makes sure that the heart beats regularly. In supraventricular tachycardia, these signals aren't passed on properly. They then get "stuck" in the AV node and circle around it. This causes the AV node to send a lot of signals to the lower chambers within a short space of time. As a result, the heart beats very fast.

PSVT can also be caused by other things, including:

• An extra electrical pathway between the upper and lower heart chambers: The electrical signals are passed on to the lower chambers, but they may also travel back towards the upper chambers. Then they circle around between the upper and lower chambers. This kind of PSVT is known as pre-excitation syndrome. There is a subtype called Wolff-Parkinson-White (WPW) syndrome. Having this subtype can increase the risk of complications – especially if you have atrial fibrillation too.
• Extra heartbeats (extrasystoles): Extra heartbeats occur every now and then (even in healthy people) and don’t cause any problems themselves. But they might be a trigger, causing electrical signals to circle around the AV node or travel back and forth between the upper and lower heart chambers.
• Electrical signals from areas of the upper heart chambers that don't actually belong to the heart's conduction system: This may be the result of scarring in those areas – for example, due to heart disease or heart surgery.
• An electrolyte imbalance in the body, alcohol or drug consumption, or stress.

About 2 to 3 out of 1,000 people have a fast heart rate that arises in the upper heart chambers (atria) or the area where the upper and lower heart chambers meet. Supraventricular tachycardia is more common in women than in men. The risk increases with age.

But this isn't true for all types: Those that are caused by an additional electrical pathway between the upper and lower heart chambers are more common in men and young people.

Supraventricular tachycardia usually comes and goes in episodes: The heart suddenly starts racing, continues to beat fast for several minutes, and returns to a normal rate just as suddenly. In some people, the tachycardia (fast heart rate) can last for more than an hour.

The time between two episodes varies: Some people have several episodes a day, others have them days, weeks or months apart.

If you keep having episodes where your heart suddenly beats faster for a while, it’s a good idea to see a doctor. They will do a physical examination and ask about your symptoms. That’s usually enough to get an idea of whether you have PSVT, and what type.

Like all other heart rhythm disorders, PSVT can only be diagnosed for sure by doing an electrocardiogram (ECG). But the fast heart rate may not occur while you’re having a short ECG done. Because of this, a continuous ECG recording is often done for 24 hours or longer. That involves wearing a small ECG monitor around your neck (under your clothing), for example. The device is connected to electrodes that are placed on the skin of your chest. Special recording devices called event recorders can record the heartbeat over longer periods of time (up to several years), detecting even rare episodes of heart rhythm disorders. These devices are so small that they can be implanted under the skin.

The exact cause of paroxysmal supraventricular tachycardia can be determined with a special examination of the heart (an electrophysiological study) that is done using a catheter. This examination is mainly done if

• it’s becoming clear that you will need treatment with a procedure known as catheter ablation – for example, because your heartbeat is often too fast and it’s very distressing, or
• you have no symptoms, but it’s thought that there are extra electrical pathways between your upper and the lower heart chambers. This is mainly true for athletes and people in responsible positions, such as airline pilots. The electrophysiological study (EPS) allows doctors to see the electrical pathways of the heart in more detail. That helps them to determine whether there’s an increased risk of complications such as ventricular fibrillation.

To find the exact causes, more examinations may be done – like an ultrasound scan of the heart (echocardiogram) or an examination of the thyroid gland.

Paroxysmal supraventricular tachycardia (PSVT) generally doesn’t cause any serious problems. But people who are older and have certain pre-existing health problems are more likely to faint and fall during an episode – and PSVT is also more likely to damage and weaken their heart.

To assess the risk of complications, the cause of the fast heart rate will also play a role: If, for example, it’s caused by an additional electrical pathway between the upper and lower heart chambers (pre-excitation syndrome), PSVT could trigger life-threatening ventricular fibrillation. The risk of this happening is particularly high if you also have atrial fibrillation.

There are two different types of treatment for paroxysmal supraventricular tachycardia (PSVT):

• Treatment to reset the heart rhythm
• Treatment to prevent PSVT episodes in the long term

Special breathing techniques (known as the Valsalva maneuver) have been shown to slow down the abnormally fast heart rate. They involve holding your breath and pushing down into your abdomen (belly area) to increase the pressure there – a bit like when trying to stop hiccups. This is often done together with certain physical positions, like putting your legs up. The Valsalva maneuver stimulates the vagus nerve, which leads to the heart and can slow down the heart rate. The vagus nerve can be stimulated in other ways too – for instance, by quickly drinking a glass of cold water.

You can use these techniques yourself to make your heart rate return to normal. They are also the first treatment of choice if you go to a doctor’s office or hospital. If it doesn’t work, medication is injected. If that doesn’t help either, or if the fast heart rate leads to a serious blood circulation problem, treatment with a controlled electric shock (cardioversion) is tried out to reset the heart rhythm.

As well as treatment to reset the heart rhythm, you can also have treatment to prevent further PSVT episodes in the long term. This is considered if you often have episodes of a fast heart rate and they cause symptoms. One effective treatment is a procedure known as catheter ablation. Here a thin tube ( catheter) is fed into a vein and pushed through to the heart. Then abnormal heart tissue is destroyed (ablated) on purpose. Sometimes catheter ablation is also recommended for people who don’t have any symptoms – but only if their PSVT is more likely to lead to life-threatening complications. As an alternative to catheter ablation, you can have long-term treatment with medication.

No treatment is needed if you are otherwise healthy, don’t have a higher risk of complications, and only have rare episodes of PSVT that don’t bother you much.

When people are ill or need medical advice, they usually go to see their family doctor first. You can read about how to find the right doctor in our topic "Health care in Germany" – and our list of questions can help you to prepare for your appointment.