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ECG questions

Hello,

I have a question about some ecg changes. A year ago I saw a cardiologist who have me a perfect bill of health after an echocardiography.

6 months ago, I had an ecg and the computer readout said left axis deviation and LBBB. The doctors reviewed the ecg and said that everything was fine and that the ecg had made the wrong diagnosis (apparently common with the electronic diagnoses) I was happy with that and left without a worry.

Yesterday I had a further ecg (to check my qt interval as I am withdrawing from zoloft and it had previously caused a slight prolongation of my qt interval (470ms). I was so nervous during the ecg that my heart rate was around 120 bpm and I felt a few pvcs etc.... The computer diagnosis said 'sinus tachycardia" and "left anterior hemiblock". My GP said he didn't think I had a hemiblock, but noted the QRS duration was a little wide - 55ms. In any event, he said don't worry and didn't refer the ecg to a cardiologist.

My question is why two recent ecg reports have shown some form of left sided block. I am 30, female, non-smoker in good health. My only health problem is severe (often heart focussed) anxiety/panic attacks and mild white coat syndrome (my highest bp was 155/97 during a panic attack).

Is it possible that 10 years of severe anxiety may have caused an electrical defect? Thanks so much for your help.
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1124887_tn?1313758491
It depends on what you mean by accurate.

It's accurate, but at increasing heart rate (somewhat depending on the cause for an increased heart rate), some changes may occur:

1. The corrected QT time may increase, as Bazett's formula may over-correct at high heart rates. Especially if QRS is widened.

2. QRS voltage may increase, falsely reading left ventricular hypertrophy.

3. PR time may decrease, caused by adrenaline stimulation decreasing conduction time.

4. Axis may change, but up to 120-130 bpm, the axis usually turns rightwards, at even higher bpm it turns leftwards again. My QRS axis is at rest 55-60 degrees, increasing to almost vertical axis (90 deg) up to 130 bpm, then turning left again.

5. Some people may develop non-specific ST changes at higher heart rates. If they persist or worsen at even higher heart rates, and especially if they are accompanied by chest pain or other symptoms, testing for CAD is warranted. However, rapid heart rate driven by anxiety can often produce ST changes at 120 bpm or so that returns to normal at higher heart rates.

Sorry for a slightly technical answer.
7 Comments Post a Comment
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1124887_tn?1313758491
Hello.

No, it's not possible for anxiety to cause LBBB or LAHB. I'm not able to say if you have one of those or not, but if you do, it has nothing to do with anxiety.

Some further comments:
If you have a wide QRS complex (I assume it should be 155 msec and not 55, as 55 is very narrow), your QT time will be "falsely" prolonged. As you know, QRS duration is a part of the QT interval, where the relevant part is actually the JT interval (end of QRS complex is known as the J point or junctional point). If your heart rate is high (but QRS still wide) you will have this effect markedly increased on your "corrected" QT interval.

I would recommend that a cardiologist take a look at your EKG, just to get this cleared up once and for all. As an alternative, you could scan it and post it in the Heart Disease Expert Forum for a cardiologist to look at it.

Good luck!
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Avatar_f_tn
Thank you so much for your comprehensive response! I will refer it to a cardiologist, though my gp will be annoyed about this

I think the qrs may have referred to the axis? Perhaps it was -55 which suggests left axis deviation.

The other thing I am wondering is whether an ecg can be very accurate with a heart rate of 120 bpm!
Blank
1124887_tn?1313758491
It depends on what you mean by accurate.

It's accurate, but at increasing heart rate (somewhat depending on the cause for an increased heart rate), some changes may occur:

1. The corrected QT time may increase, as Bazett's formula may over-correct at high heart rates. Especially if QRS is widened.

2. QRS voltage may increase, falsely reading left ventricular hypertrophy.

3. PR time may decrease, caused by adrenaline stimulation decreasing conduction time.

4. Axis may change, but up to 120-130 bpm, the axis usually turns rightwards, at even higher bpm it turns leftwards again. My QRS axis is at rest 55-60 degrees, increasing to almost vertical axis (90 deg) up to 130 bpm, then turning left again.

5. Some people may develop non-specific ST changes at higher heart rates. If they persist or worsen at even higher heart rates, and especially if they are accompanied by chest pain or other symptoms, testing for CAD is warranted. However, rapid heart rate driven by anxiety can often produce ST changes at 120 bpm or so that returns to normal at higher heart rates.

Sorry for a slightly technical answer.
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1124887_tn?1313758491
Also, some people develop rate-dependent LBBB or RBBB. It may mean nothing, but further examination is often a good idea.
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Avatar_f_tn
Hi again!

Wow! Thanks for such a great answer - I feel very much supported just by having someone 'out there' who understands!

I would say that the sinus tachy reached closer to 140 - 150 bpm; and my heart was absolutely thumping and creating pvcs etc. All over a very horrible experience! Oh and I was nearly hyperventilating!

In any event, I am calling the cardiologist tomorrow to just let him know. I hate the fact some doctors get offended if you ask for a second opinion - I know mine will!! His attitude was that I should just forget about it!

But how can you just ignore what seems to be a sudden left anterior hemiblock?! Assuming the QRS calculations on the ECG weren't messed up by my exceptionally anxious state in which case the electronic diagnosis is probably meaningless.

Thanks again!!
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1124887_tn?1313758491
Hi, and thanks for rating my answer. I really appreciate it :)

You're welcome, and just ask if you have further questions!

Regarding the LAHB, I can't say for sure if you have that or not, the diagnostic criteria is usually basically (as far as I know) left axis deviation in the absence of other causes, such as thickened left ventricle, etc. If your echo was fine a year ago, I would try to think "my heart is healthy". LAHB can occur in healthy hearts and isn't necessarily problematic.

Of course, this is easier said than done (and believe me, I know). It's always very discomforting to have doubts if your doctor did misinterpret something (and we always tend to trust the worst case, don't we? ;) That's why I suggested you could ask a cardiologist to take a look at your EKG.

I believe you will feel a lot better after you've got a cardiologist's opinion on this.
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Avatar_f_tn
Thanks so much!! I do have one question - the one my doctor didn't answer and that is why a young healthy person would suddenly have LAHB? It seems crazy and a bit worrying (I'm only 30).

My only risk factors (as previously said) is very severe anxiety which, over 10 years has frequently caused palpitations and tachycardia. I can't stress how bad this has been my heart rate goes through the roof and often too.

I'm also plucking up the courage to ask my GP to refer the ecg to my previous cardiologist, hopefully this will ease my mind!

Thanks again, you have been so supportive!
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