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Long QT or Not!?!?! Someone HELP!

Hi Everyone! I have been on a very long and complicated journey with my heart for the past year. So I'll try to make this as short and uncomplicated as possible! Lol SO. I've been to the ER with my heart more times than I can count. Seen two diff cardiologists & one Electrophysiologist & a neurologist. So everytime I go into the ER my ECG comes back "Abnormal" "Sinus rhythm with short PR" and "ST & T wave abnormality". I've been admitted twice and spent a week in the hospital on my last stay. I've had stress tests done as well as the neuclear. Echo done which revealed that I have mild Mitra Valve Prolapse. But my stress tests and my blood work come back fine. And while I was in the hospital my heart rate would be fine while sitting but skyrocket upon standing to like 160. They keep saying well we know something is wrong just don't know what. I've also worn a event monitor which caught a rythem of 186 that woke me up in the middle of the night. I've had two episodes like that this year. And I also have extremely low blood pressure. I've worn a halter that my EP said was completely normal. Now the neurologist told me I have Dysautonomia/Mitra Valve Prolapse. So I started seeing the top cardiologist in that field, he invented the test for dysautonomia. Anyway. So on my visit he did a routine ECG and I noticed it was borderline LONG QT!! He looked at it and said no the machine is probably wrong, it doesn't look long to me. SO. Me being me I've pulled out all the ECG's I have here at home and have used the Long QT calculators online and they are all saying that my QTc is wayyyy longer than the ECG calculated. So my question is, is this possibly accurate?? Is there more to be considered than the numbers I'm typing in on these online calculators.
Example my last ECG
Heart rate - 90 bpm
PR int: 108 ms
QRS dur: 86ms
QT- 390
QTc- 438
Which is suppose to be normal QT interval. Well when I do it on the online calculator it comes back as QTc of 478!!!!!
What is the deal here!? I'm freaking out! And yes I've made sure the speed on the machine is 25mm and everything I'm typing in is right. And ALL my ECG's are this way. They always so ST-T wave abnormalities & They show readings of borderline Long QT but then when I calculte them online they are wayyyyyy off. Like in the red zone for LONG QT! Somebody HELP!!!  
2 Responses
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1124887 tn?1313754891
I can tell you why there is a difference.

The calculators online are using the old Bazett formula for calculating QTc. What those formulas do, is trying to determine "what the QT interval (which shortens at higher heart rates and prolongs at lower) would be if your heart rate was 60". The Bazett formula is (in-)famous for over-correcting the QTc at high heart rates (making it longer than it would be at heart rate 60) which is why your EKG machine is using the newer Fridericia formula which doesn't over-correct QTc at higher heart rates.

I have also experienced that my QTc is "prolonged" when I had panic attacks when EKG was registered and my heart rate was high. I was just telling the doctor "ah, you're using Bazett" when my QTc was in the 460s and my heart rate was 130. Bazett doesn't work as well at heart rates above 80.

Preferrably, you should register an EKG when your heart rate is slow (closer to 60) to find your "true" QT interval. The formulas used are just theoretical approaches to what your QT interval likely would be at slower heart rates. Every person have their unique relationship between QT interval and heart rate. In some people, QT interval narrows much with increased heart rate and in some people it doesn't.
Helpful - 0
14991338 tn?1447193706
is something wrong is a excellent member of med help heart rhythm. always answering and for the most part online.

On the subject ( hope this is ok BBECK3 ), would you be able to tell me why the q t time varies on different days?
so may people i have spoken to on here, and from my own experience, we have had ecg's multiple times and sometimes the q t interval in quite largely different. once mine was around 420 calculated and most of the time now its around 390 calculated ?
Helpful - 0
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