Last sunday my 12 year old daughter stood up quickly from the couch and fainted without warning. This had never happened before. She came to almost immediately and said she felt fine. Just prior to fainting she had been sleeping for about 12 hours and also had had nothing to eat or drink for close to 14 hours.
When we took her to the ER they found that her QT was 459. The next day the EKG was repeated and was 441. The pediatric cardiologist who read it called the second reading 'high normal"
What is the probablility with this faint and with these numbers that she has long qt? I am terrified of course. Does adolescence contribute to long qt? Is a qt of 441 truly "normal?"
She is a healthy active girl with no health issues of any kind.
Thank you very much for any information you can give.
Any QTc-interval above 440 milliseconds is considered prolonged.
Borderline QT shows a prolongation of QTc, but not prolonged enough to clearly make the diagnosis.
450 to 470 milliseconds is considered borderline. The average QTc for someone who has long-QT syndrome is 490 milliseconds.
A QTc at or above 480 milliseconds in females or 470 milliseconds in males, is probably a sign for long-QT syndrome, in the absence of drugs, electrolyte disturbance, or other conditions that might independently lengthen the QT-interval.
It's difficult to say if her syncopal episode was related to a disturbance in the electrical conduction of her heart. You did mention that she had not had anything to eat or drink for quite some time and that she stood quickly from a sitting postiion. The epeisode could have been what's called a "Vaso Vagal Syncope" Did they check her electrolytes when she was evaluated? At any rate, I would make an appt. for her to see her Primary Care Physician who may suggest a consult with a pediatric cardiologist.
I can only speak from what I've experienced, but the QT time varies all the time, depending on heart rate, adrenaline levels (affects conduction time in the heart), what you eat (potassium, sodium and calcium levels) and what you drink.
I've measured a QTc of 456 msec on EKG, but also a QTc of 340 msec. The formula for calculating QTc (QT time varies with heart rate, and the formula tries to estimate what the QT would be in this EKG if the heart rate was 60) tends to overestimate QT time at high heart rates and underestimate on low ones.
It is possible (and very likely) to have QT prolongation without having the genetic LQTS disorder. LQTS is often found on EKG not only by prolonged QT, but a somewhat mis-shaped T wave that would probably make your doctor suspicious.
Low potassium levels will cause QT prolongation.
Syncope with LQTS often occur at rest with bradycardia (causing a QT time above 600 ms) or with high activity (there are different LQTS disorders). Syncope appears brutal and occurs with a heart rate often above 250 (ventricular tachycardia with the french name Torsades de Pointes). It's unusual to wake up immediately, this is a sign of vasovagal syncope as Brooke said.
I'm going to give you my perspective from a sufferer since the age of 9 (43 now).
I used to do things like your daughter, I would go to answer the phone or stand up to go somewhere and bam I was on the floor or grabbing something not to hit the floor; PE was always a nightmare. I was the typical teen and didn't eat enough, always on the go - sports school etc and never watched my fluid intake; sometimes I slept alot then wouldn't sleep at all. Dr's always said it was due to a response in the change of my blood pressure.
As a child, teen and adult I have fainted sitting, standing, driving or just changing my positions; even turning my neck. Not all of the time am I out for long periods of time, sometimes it's just a split second of unconsciousness, but over my lifetime worsened.
Fast forward to age 43; I am now finding out it wasn't just the BP response. My EP says apparently I've had a neurological problem (NCS & OI) causing this that has just worsened over the years and mine is found to be connected with heart issues or causing them.
Your daughter may never faint again and it's nothing to worry over, or she may have something else going on that needs careful watching. She def needs a full workup and make sure all her levels are where they're supposed to be and I would ask for a cardiac workup as well just to be on the safe side. The other thing you can mention to the pediatric cardiologist is a head up tilt table test that may rule out certain conditions.
If it turns out to be nothing, you have cause to celebrate, if not let us know =)
I don't mean to alarm you but this is something I would take very seriously. ECG machines are not accurate and most doctors do not take prolonged QTs serious enough... trust me from experience. I was 11 when I first starting fainting and was lucky enough to never have a cardiac arrest and I now have an ICD. Is there any family history of sudden death, drownings, seizures? Sometimes people with Long QT Syndrome appear to have seizures when they faint but they are not true seizures and some people get falsely diagnosed with Epilepsy.
An ECG machine will say that my QT interval is around 460, which is high normal for a woman, but when read by an EP it is really way over 500. The problem with the ECG machine is that it takes an average of QT intervals across the ECG but some leads could have much longer QT intervals than others and that is the need for her ECG to be read manually by an experienced Long QT Syndrome EP (Electrophysiologist-Heart Rhythm specialist). There are other things like T wave abnormalities that are common in Long QT Syndrome that doctors, and even cardiologist, don't pay attention to but can help EP make a diagnosis.
You could contact SADS (www.sads.org) or CARE (www.longqt.org) and ask for a specialist in your area. Please trust me when I tell you that regular doctors and most regular cardiologists DO NOT know enough about LQTS to diagnose it. Even after my son had a cardiac arrest we were not taken seriously and I had to search the internet for specialists on my own.
If you can, get a copy of her ECGs and take them with you to see the specialist. They will probably do a stress test, maybe a holter monitor and sometimes an adrenaline challenge test is done. This is where they give IV drugs and watch the heart on monitors to see if the QT lengthens under stress.
Please feel free to contact me with any questions. Don't panic but please look into this further. Try to keep your daughter well hydrated and extra bananas and other foods high in potassium wouldn't hurt either. Loud sounds like phones and alarm clocks can trigger events so keep these down too.
I am so glad to see you have been on here answering this question, stevie. I agree with you that she needs to be seen by a Pediatric Cardiologist as well as an EP Specialist A Tilt Table Test would also be a good test to do based on what happens. Also, the fact that your daughter is a child, only 12, the EKG measurements may be different from the adult. A child's EKG does have differences from an adult. Take your daughter and have her evaluated further; I'm surprised the ER staff did not do that for her.
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