Supraventricular Tachycardia (SVT) - General Information
Supraventricular tachycardia SVT is a very common condition in which the heart suddenly goes very fast (often over 200 beats per minute), and just as abruptly goes back to a normal rate. The actual heart rate is usually the same for each episode for a given person - If the heart rate was 210 the first time, it will almost always be 210 every time. Depending on how fast the rate is, and how long the episodes last, people with SVT can experience a sensation of a racing heart, dizziness, shortness of breath or chest pain. If SVT lasts a very long time (days or more), the heart can be injured by the fast rate, but usually SVT has no adverse effects on the heart.
Some people with SVT also have a condition called Wolff-Parkinson-White Syndrome (WPW). Their SVT is very much like anyone else's, but they have special issues that bear on whether to proceed with radio frequency ablation (see below).
SVT is usually triggered by a premature heartbeat, not (as is commonly supposed) by activities like exercise that make your heart go faster otherwise. Most people have some premature heart beats over the course of a day, most commonly at times when their heart is beating at a somewhat slower rate (reading, watching TV) or when their heart is slowing down (such as after exercise). Some people have more premature beats, and more episodes of SVT, when they are excited, or if they have a stimulant on board such as caffeine or certain stimulant medications.
It is very hard to try to avoid SVT by limiting a child's activities. First of all, it almost never works, and can even backfire if a child becomes angry at being told not to run or "get wild". Second, it sends a child the message that they can't do things that other children can, which may harm their self-esteem. Finally, it creates a lot of tension between a child and his or her family, since children need to assert some control over what they do as a natural part of development.
The most useful measures for controlling SVT in most children are vagal maneuvers, such as bearing down (making your face red), hanging upside down, or ice water pack to the forehead and bridge of the nose (for no more than 30 seconds), etc. If SVT is interfering with a child's life, or is thought to be a safety risk by their cardiologist, one can consider eliminating the cause using catheter-delivered radio frequency ablation. There are only a small number of centers with a large experience with this procedure in children, but it is probably important to seek one out if this procedure is necessary for you or your child, and you don't happen to live near one. Medications are a solution if the episodes are interfering with a child's quality of life, or are concerning from a safety perspective, particularly if RFA is not thought to be a good solution or is not available.
Very often, people with SVT will have episodes of tachycardia for a period of time (months to years), followed by a period of time without any episodes. This is particularly common in childhood, and many children with SVT in infancy have no episodes later in life. Because of the tendency for SVT to go away, it often makes sense to "live with it" if the episodes are felt to be safe, and the symptoms are controllable or bearable, rather than rush to RFA or medications.
Some Internet links that may be helpful include:
A number of articles about SVT and WPW