Unsuccessful Ablation

[JenRaw]

I have a 7 year old boy with WPW.  My son had an ablation in January.  All was clear at the 1 month follow up, but his EKG was suspicious at the 6 month.  He just had an SVT episode which confirmed that he will need a second ablation procedure due to WPW.  Why was the first one unsuccessful in the end?  If this other pathway was there, then why was it not seen on the first EP study?  Is it common to have to have a second ablation?    What creates the need for a second ablation?  Did the first one not take, or did another pathway occur?  If it doesn't work this time, what are our options?
Thank you for your time.

[PikaPika88]

Back to 1985, I had my His bundle ablation to stop the palpitations.  I was diagnosed wpw and medicated at 15 years old.  After the ablation, I had a heart block.  During the heart block, a new anterograded pathway formed to start the conduction.  AV node was not function anymore till now but I have my own heart beats via the pathway (I don't know can it call accessory pathway or not because I only depend it to do the conducting).  Doctors said the accessory pathways won't grow.  It manifests but I still believe it can grow.  

[Jeffrey R Boris, M.D.]

Dear Jen,

Unfortunately, this can be frustrating for families when this happens.  For our other readers, Wolff-Parkinson-White syndrome (WPW) occurs when there is an extra (or more than one extra) electrical connection between the top and the bottom of the heart.  The extra pathway can allow for an abnormal heart rhythm (arrhythmia) called supraventricular tachycardia (SVT).  SVT is a fast abnormal rhythm, or tachyarrhythmia, occurs when the electrical signal goes down the normal pathway and back up the extra pathway; less commonly, it can do the opposite.

When the heart is first forming, there are many electrical connections between the top and the bottom of the heart.  However, over time, these go away and leave just the one connection:  the atrioventricular (A-V) node.  If one or more of these connections remain, they can cause SVT.  Your son underwent an ablation, in which several catheters were placed in his heart to electrically map the heart.  This was likely done under anesthesia.  The extra pathway was found, and then an ablation catheter was placed on the pathway.  Depending on which method was used, it was either burned, with radiofrequency ablation, or frozen, with cryoablation.

Obviously, I can’t tell exactly what happened with your son’s ablation experience.  However, there are a couple of possibilities here.  When the ablation occurs, it destroys the cells in the pathway.  However, it also causes damage to some of the cells around it.  This leads to local swelling, or edema.  This edema can cause the electrical conduction in the area to disappear or be very slow.  The edema can take a while to resolve.  Therefore, the pathway may not have been completely ablated OR there could have been more than one abnormal pathway, in which one was ablated and one was temporarily damaged.  Another potential cause is that the anesthesia changed the conduction properties of the electrical pathway so that it seemed to go away.  This is less likely, though, as your son’s ECG was normal at one month.  Also, there are very good anesthetic agents now that cause minimal electrical conduction problems, so if your electrophysiologist performs a large number of ablations, this is probably not the problem here.