Supraventricular Tachycardia

We were informed that our son has a condition called supraventricular tachycardia. We would like to know about it. Is there a procedure that can eliminate the problem?

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Robert Steele

Robert W. Steele, MD, is a board certified pediatrician at St. John's Regional Health Center in Springfield, MO. He graduated from medical... Read more

Supraventricular tachycardia is a condition which causes the heart to beat very quickly (200-300 beats/minute) for an extended period of time. It is the most common cause of a heart rate this fast in children and occurs in 1 of 250-1000 kids. But one must first understand how the heart normally beats to understand what happens when it goes awry.

The heart is amazing organ in that it contains millions of individual cells, yet they all normally contract in a rhythmic manner coordinated with each other. This beating is initiated by a natural pacemaker called the sinoatrial node. This SA node located in the upper half of the heart generates an impulse at a rate which depends on the age of the child and the level of activity in which the child is involved. Once the impulse is generated, it follows a very specific path toward the lower half of the heart passing through what is called the atrioventricular node. From there, the impulse travels through the lower half of the heart. This impulse does not travel in the most direct route to go from the top to the bottom allowing for the cells on the top half of the heart to contract just before the bottom ones do. This, in turn, allows for efficient pumping of the blood to the rest of the body.

In supraventricular tachycardia (SVT), the impulse takes a different more direct route from the top to the bottom. In addition, the most common type of SVT in children allows for this impulse to travel in a circle such that the impulse travels from top to bottom quickly but then continues in a route back to where it started stimulating that impulse all over again. You can see that this would cause a fast heart rate because the impulse is feeding back on itself.

The symptoms of this occurring depend on the age of the child. In newborns and infants the most common symptom is poor feeding, however, other symptoms include fast breathing, and lethargy. In older children, a feeling of the heart racing is common,as well as chest pain, dizziness, and fainting may occur. In both sets of children, if you try to take the pulse, you will find it too fast to count.

There is a procedure called catheter ablation that usually cures the problem especially for those whose SVT is caused by the circuitous impulse pathway described above. This is a procedure in which the cardiologist passes a catheter through the blood vessels into the heart. Then through electrical mapping, the abnormal pathway may be plotted. A small electric current is used to kill the heart cells in that pathway thus eliminating it.

A child who has the condition of SVT will only go into the fast heart rate intermittently. And when this occurs, most children feel uncomfortable but do not have life threatening difficulty with the pumping of the blood. There are certain things that may be done at home to get the heart beating in the correct manner, however, they should only be done after a thorough evaluation by a doctor has been done and the manuevers are deemed appropriate. Most children can be managed well with medication. However, if a predisposing factor to SVT is seen on the EKG, significant life-threatening symptoms occur when the SVT occurs, or the SVT is not well controlled on medication, catheter ablation may be most optimal. I suggest you talk with your doctor about all the options.

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