What Is Pre-Excitation (From An EKG) And Is It Dangerous?

Question: On a routine EKG I was diagnosed to have pre-excitation. What is that and is it dangerous?

Answer :Pre-excitation is a term used to describe the early delivery of an electrical impulse to heart muscle prior to when it should normally be arriving. This condition is also known as Wolf-Parkinson-White Syndrome, or WPW. It's due to the presence of an extra pathway from the upper or atria to the lower or ventricular chambers of the heart. This is a pathway that is normally present in fetal or embryonic life, but that is supposed to disappear completely by birth. In those people in whom it doesn't disappear, we are left with that extra pathway.

The pre-excitation refers to what's seen on an electrocardiogram. The condition predisposes patients to a short circuit in the heart where an impulse can go down one pathway and up another when that second pathway shouldn't be there. This can cause very rapid heart rates that can be symptomatic in terms of patient comfort, but in most situations are not dangerous.

There is one circumstance in which Wolf-Parkinson-White or pre-excitation is dangerous, and that's when it occurs in patients who are also prone to have atrial fibrillation. In these patients, the presence of both conditions creates a risk for life-threatening heart rhythm disturbances and requires aggressive management. Patients who have pre-excitation and atrial fibrillation or are at risk for atrial fibrillation will generally be recommended to have an ablation procedure, which means going in with a catheter or wire into the heart, finding the extra pathway and delivering energy to that site to burn out the pathway. This procedure has a very high success rate and removes the danger associated with the risk of atrial fibrillation in pre-excitation.