Case
Hi thanks for taking my call. I’m a local psychiatrist and I obtained an ECG on this 7-year-old boy who I follow and was recently diagnosed with ADHD. The reading from the ECG machine says it is “abnormal” with a comment at the top saying “Evidence of Ventricular Preexcitation.” The child has been asymptomatic and has never complained of any heart related concerns to my knowledge. I am wondering if it is OK to start him on ADHD medications or if I should have him see you?
What am I thinking?
My first reaction is to get a copy of this ECG sent to me for my direct review. If the ECG does show evidence of preexcitation then we are most likely dealing with a child with asymptomatic Wolff-Parkinson-White (WPW) syndrome. This brings up two issues; namely the issue of asymptomatic WPW and how best to manage that, and secondly, the safety of ADHD medications in someone with WPW. In this case, given the desire to start ADHD medications, I would recommend that the child be seen by a pediatric cardiologist or electrophysiologist to meet with the family and discuss the benefits and risks. We will also have an opportunity to discuss the management of WPW and what options we might have to pursue.
| Tachycardias possible with WPW | QRS appearance |
|---|---|
| Atrioventricular reentrant, orthodromic (down AV node) | Narrow |
| Atrioventricular reentrant, antidromic (down accessory pathway) | Wide |
| Atrial fibrillation with rapid ventricular response (via accessory pathway) | Wide |
| AV nodal reentrant tachycardia (bystander pathway- not involved) | Narrow |
History and physical
The first step for evaluating a child with a WPW pattern on ECG is to elicit any history of symptoms. Symptoms can include a feeling of tachycardia or heart racing as well as syncope. Depending on the age of the child, this can sometimes be difficult to elicit. Using colloquial descriptions such as “heart beating out of your chest,” “fast beeping heart,” and other terms may provide a better history from the patient. Requesting history from the parents about times in which the child complained about the heart or chest may also be helpful keeping in mind that complaints can often be nonspecific.
The estimated prevalence of WPW is approximately 1–3 per 1000 individuals. WPW pattern on ECG demonstrates a shortened PR interval with a widening of the QRS and lack of Q waves (see Figs. 13.1 and 13.2A ). This is created by the presence of an accessory pathway that bypasses the typical atrioventricular node allowing for excitation of the ventricle before the normal conducting His-Purkinje system (i.e., ventricular preexcitation). Most accessory pathways can result in the risk of a reentrant form of SVT. This can be by conducting down the AV node and back up the pathway, termed orthodromic, which would result in a narrow complex tachycardia. This can also be by conduction down the pathway and up the AV node, termed antidromic, which would result in a wide complex tachycardia. This wide complex tachycardia may be confused for a ventricular tachycardia (see Fig. 13.2B ).
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