Junctional Escape Rhythm in Children --Doctors Lounge(TM)

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Forum Name: Arrhythmias

Question: Junctional Escape Rhythm in Children

stevie13wonder - Wed Dec 27, 2006 12:12 pm
My 9 year old is undergoing testing for Long QT Syndrome. He has had an exercise stress test done and is having an adrenaline challenge test done soon. On his stress test he had junctional escape rhythm upon the standing ECG, hyperventilating ECG and during the recovery ECGs. His heart would go from 100 to 50 bpm. Is this normal, I have read that this can lead to TdP in the long qt syndrome. I have only read that junctional escape rhythms happen in children during sleep and in athletes. Any info would help Thanks, Stevie
John Kenyon, CNA - Wed Dec 27, 2006 4:25 pm
Hello Steve - I am wondering what caused your son to initially be brought in for LQT testing. Did he have any fainting episodes or other symptoms suggestive of LQT? Is there a family history of LQT or deafness? These things are very important factors in sorting out this sort of problem so that it can be treated appropriately. The fact that your son exhibited a junctional rhythm upon standing and hyperventilating is odd for a person with LQT, but of course not unheard of. It seems more likely to suggest a blocking of some portion of the conduction pathway or an abnormal slowing (as in what is known as vagotonia, an inappropriate slowing of the heart by the vagus nerve as in dysautonomia). These conditions are generally less worrisome than Long QT, but still would need to be addressed. And of course, if there is a family history of LQT, then all this could simply be prelude to a more complete presentation of LQT symptoms (usually fainting upon being startled by a loud noise, during stress, etc.). This sounds, based on what you've reported, as though the AV junction is temporarily taking over the pacemaking duties because of an imappropriately slowed sinus rhythm. The fact that it may be cutting the rate in half sounds like there could actually be some sort of intermittent block, but I am thinking vagal stimulation is more likely because it occurred upon standing and with hyperventiilation, two things which can stimulate an overly sensitive vagus nerve. Your son might have some variant condition that could cause symptoms similar to LQT, which would be a more benign diagnosis, although Long QT is treatable. It needs to be very accurately diagnosed, however, in order to treat it effectively. If the problem is vagotonia instead, there are different therapeutic approaches. I am not familiar with a direct correlation between a junctional rhythm and TdP, although there can be an indirect relationship. TdP is the usual arrhythmia seen in LQT patients. A junctional escape rhythm is a backup system built in to take over for a too slow heart rate resulting from vagal stimulation or one of the higher degree heart blocks. Symptoms of either of these and LQT can be similar, but the causes really quite different. I hope you get a concrete answer soon, so that you can relax and know that the problem will receive the appropriate treatment. I hope this is helpful.
stevie13wonder - Wed Dec 27, 2006 4:47 pm
Yes this information is very helpful. My son showed borderline Long QT on a few ECGs he had done to investigate a heart murmur that the doctor found while checking him over because he was having dizziness and near fainting spells while swimming and playing hockey. His exercise test showed a QT interval of .478. There is a family history of collapse and sudden death in my mothers family as well, including my sister with a near drowning at the age of 13. My 19 year old son fainted while running about 9 months ago and went into cardiac arrest. It was diagnosed as asthma at the time because he has had severe asthma his whole life and had taken several puffs of ventolin before running. He has since had an ECG showing Borderline Long QT as well. We are just waiting to see his ECGs from the night he was brought into the hospital. The cardiologist we saw that night said that his QT was prolonged because of the ventolin. But I don't have much faith in that cardiologist just by the way he treated us then. The new cardiologist we are seeing is much more thorough. The kids are all scheduled for adrenaline challenge tests soon so a treatment plan can be put in place. The cardiologist also mentioned an AV block about my 9 year old but said that this can be secondary to Long QT Syndrome. Thanks again Stevie
John Kenyon, CNA - Thu Dec 28, 2006 10:22 pm
Hello again - With that family history it seems rather likely your child does have evolving Long QT syndrome. The junctional escape rhythm probably has been functoining as a backup during loss of normal ventricular stimulation. Also, families with a history of electric derangement of the heart's conduction system can have variations and/or additional abnormalities. The episode your 19 year old experienced may well have been the equivalent of an adrenaline challenge as the combination of natural adrenaline (released during an athletic activity) plus the ventolin, which is powerful medicatoin similar in effect to adrenaline. The doctor who observed that the long QT interval at the time was probably caused by the ventolin seems to have missed the greater point that anyone predisposed to Long QT is likely to have it increased by use of any epinepherine-like drug. Long QT, as you probably know, can be intermittent and can also be acquired (usually due to use of certain medications). Use of beta blockers is often recommended therapeutically for confirmed LQT, and can provide a fair degree of protection. There are also implantable devices available for appropriate subjects. The important thing is that this condition can usually be managed, although sometimes some lifestyle changes have to be made as well. It seems you are now in good hands with the new doctor, who appears to be doing all the necessary and appropriate things. I wish you and yours all the best. Please keep us updated.

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