Atrial tachycardia in children (also know as atrial ectopic tachycardia or AET) is an arrhythmia, or abnormal heart rhythm that causes a fast heart rate. Normal electrical conduction in the heart starts with the generation of electricity in the sinus node in the upper portion of the right atrium. Electricity moves from the sinus node through the atrium. From there, it is transmitted to the AV node to the ventricles. At electricity passes to the ventricles, the heart muscle contracts.

Syncope is the medical term for fainting. Syncope is one of the more common heart related symptoms in children and teenagers. In fact, some experts have estimated that up to 50% of children will have a fainting spell at some point during their childhood or teenage years! Fortunately most episodes of fainting in children have a relatively benign cause.

To understand normal electrical conduction, it's first important to have an understanding of normal blood flow and normal heart anatomy. The heart functions to pump blood to the lungs and the body. In order to pump, the heart requires an electrical impulse just like any other muscle in the body. With normal electrical conduction, electricity for the heart originates from the sinus node in the upper right corner of the right atrium. Electricity then spreads across both atria before reaching the AV node where it momentarily pauses. From the AV node, electricity then rapidly passes through the right and left bundle branches to reach the ventricles. As electricity passes through the ventricles, the muscle is stimulated to contract.

The heart itself requires blood to work properly just like any other organ in the body. The normal coronary arteries serve the purpose of giving the heart muscle blood.  The coronary arteries originate from the aorta just above its takeoff from the heart. Normally there are 2 coronary arteries, the right and the left. The right coronary artery supplies blood to the right atrium, right ventricle, the bottom portion of the left ventricle, and the back part of the ventricular septum. The left coronary artery divides into 2 major branches: the left anterior descending and the circumflex. The left anterior descending supplies blood to the front and bottom of the left ventricle, as well as the front portion of the ventricular septum. The circumflex supplies blood to the left atrium and the back portion of the left ventricle. Venous blood draining from the heart muscle returns by way of the coronary veins to the coronary sinus which eventually drains into the right atrium.

An atrial septal defect (ASD) is a hole in the atrial septum, the upper wall of the heart separating the right and left atria. Intervention is occasionally necessary to close an ASD in a child. This most commonly occurs in the setting of a large or moderate size hole. The most common indication for intervention is the presence of dilation of heart chambers, specifically the right ventricle, due to long-standing excess blood flow. Typically intervention in children is performed between 2 and 5 years of age, although it can easily be accomplished earlier if necessary.

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