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With the heart's natural pacemaker being in the atria (the top part of the heart), it's no surprise that many types of abnormal heart rate (arrhythmia) have their origin there.

In the heart, the three most notable things that produce your heartbeat are your atria, your ventricles, and your sinoatrial (or sinus) node. The sinoatrial node can be considered your heart’s natural "pacemaker", it’s in the right atrium (one of two atria in your heart) and sends electrical signals that cause the atria to contract. Then the signal passes through what is called the "AV node", and to the ventricles. This makes sure there is a pause between the contractions of the atria and the ventricles. Once the atria fill with blood from the body, it’s passed to the ventricles, then out of the heart again.

It may sound complex, but an easy way to remember it is that a natural pacemaker pushes blood into the top of the heart, then to the bottom, then out of the heart.

With such a complex system, it’s not difficult to see how it could be disturbed or damaged. Abnormal heartbeats are called arrhythmias, but conditions known as supraventricular tachycardias (SVTs) fall under arrhythmia. Essentially, this means an abnormally fast heartbeat (tachycardia) above the bottom of your heart (supraventricular). These are quite common, and can cause several undesirable symptoms as they affect such an important part of the body.

What symptoms can I expect with supraventricular tachycardia?

It’s no surprise that because of their grouping, the various SVTs have similar symptoms as well. If you start having these symptoms and they’re unexplained by another cause (catching the flu and fatigue, or exercising and a racing heart), it’s important to talk to your doctor about a check-up. This can be especially important as you grow older, as SVT can become more severe and deadly.

The symptoms to watch out for are:

  • A pulse that feels too fast, pounding, irregular, or fluttering
  • The sensation of feeling your heartbeat
  • Dizziness
  • Lightheadedness
  • Fainting
  • Fatigue
  • Inability to exercise
  • Shortness of breath
  • Chest discomfort

There are some symptoms unique to certain types as well; if you have atrial fibrillation you may become confused while symptoms present, and during an episode of what is called paroxysmal supraventricular tachycardia you may suffer from anxiety.

How would a doctor diagnose me?

Usually, they’ll do a physical examination first, checking your pulse and your blood pressure. They might also ask you to do some exercise, as that might help the symptoms "come out" better. After that an ECG or electrophysiology test may be done, these test the electrical activity in your heart and can help find an arrhythmia. If your symptoms are episodic, a Holter monitor, event monitor, or loop recorder may be used, depending on if your symptoms are daily, weekly, or monthly respectively.

What different kinds of supraventricular tachycardia are there?

Several different types of SVT exist, and because of their grouping, they often have similar causes, symptoms, and even treatments. It’s always important to let your doctor know if you’re presenting with symptoms because someone who isn’t a trained professional can’t accurately diagnose what is going on.

Atrial fibrillation or flutter

Atrial fibrillation is a malfunction in the heart’s electrical system and the most common arrhythmia, with about nine percent of Americans over the age of 65 suffering from it. With a normal heart, the sinus node sends consistent electrical signals telling the atria to contract at about 60 to 100 beats per minute. With atrial fibrillation, the signals are chaotic and irregular, demanding the atria contract at about 400 beats per minute. Unable to keep up with the increased demand, it quivers ineffectively, sometimes failing to move blood through the heart.

This is dangerous and can form clots, as well as raising the risk of stroke. With atrial flutter, the heart beats very quickly as well but does it in a regular, organized pattern. Atrial fibrillation or flutter can be caused by medicines, certain conditions, surgery, and heart diseases.

Paroxysmal supraventricular tachycardia (PSVT)

PSVT is supraventricular tachycardia that occurs from time to time (paroxysmal). Problems with the heart’s electrical system cause more electrical signals than necessary to pass to the atria. This can result in episodes lasting from minutes to hours in which your heart reaches 200 beats per minute or more. This condition has very specific causes, such as a medicine called digitalis and other heart conditions. However, drugs, alcohol, caffeine, and smoking can increase the risk of developing it.

Wolf-Parkinsons-White syndrome (WPW)

WPW is a congenital condition where the heart has an additional electrical pathway. Usually, the heart’s electrical signals follow a specific route, which allows the beats to happen consistently and from happening too quickly. When the beats go down the abnormal extra electrical pathway, it can cause the heart to beat at an accelerated rate.

How are these conditions treated?

What’s often done first, or if the conditions aren’t as severe, is to use drugs or electric cardioversion (shock therapy) to try to restore the heart to normal function. The drugs are rarely curative, however, and long term treatments often involve ablation (destroying the problematic area of the heart) or surgery to repair the heart’s pathways. For PSVT and atrial fibrillation, a pacemaker may also be needed.

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