QRS duration

Last year, my report after testing was:

Ventricular Rate 79 BPM
Atrial Rate 79 BPM
P-R Interval 148ms
QRS Duration 144ms
QT 420ms
QTC 481 ms
P Axis 41 degrees
R Axis 154 degrees
TAxiS 112 degrees

Atrial-sensed ventricular-paced rhythm
Biventricular pacemaker detected
Abnormal ECG
When compared with ECG of 03-MAR-2021 23:38,
Vent. rate has increased BY 11 BPM

This is all incomprehensible to me but my cardiologist says all is swell. My concern is the QRS duration. I guess I thought the pacemaker would correct that long duration. I've read about it and it seems higher than the norm still. 

This was from 2019, two years before the CRT-P implantation:


Ventricular Rate 79 BPM

Atrial Rate 79 BPM

P-R Interval 164 ms

QRS Duration 148 ms

QT 396 ms

QTc 454 ms

P Axis 28 degrees

R Axis -38 degrees

T Axis 108 degrees



Normal sinus rhythm

Left axis deviation

Left bundle branch block

Abnormal ECG

When compared with ECG of 31-JUL-2019 01:08,

No significant change was found


Any input on explaining these numbers is greatly appreciated. 


QRS Duration

by Gemita - 2022-07-20 20:12:27

Hi Lavender, I will answer your post tomorrow when I have a clearer head.

Just wanted to say that in the presence of a complete left bundle branch block (which I believe you have) a QRS duration of 144 ms would not perhaps be so unusual.  I would be reassured that all is well as your doctor suggests especially since you have a CRT pacemaker now to prevent dyssynchrony between your ventricles which will be very important.  

The CRT therapy will hopefully work on shortening the QRS width, but this may take time, although I see the QRS has certainly slightly improved, hasn’t it?

We always say here, it is how we feel, not what our numbers are telling us.  And how do you feel, that is what is important?

I will write more tomorrow.  Goodnight Lavender

Thx, you’re a Gem!

by Lavender - 2022-07-20 23:18:21

I do have both left bundle branch block and AV block. Yes a tiny improvement since pacemaker inserted. I'm trying to learn more about myself lol. 

Gemita, I checked the world clock and realized you were posting way past bedtime on your side of the pond. 

My interpretation of the data

by Gemita - 2022-07-21 14:45:03

Lavender I have gone through your latest PM report and commented and also given a few links to help us both understand a little more what some of the data means, the normal ranges and so on.  It is complex, I know, but we have to start somewhere.  I will only respond to the most recent report results, but please be aware this is only my personal interpretation of the data.  I don’t have the expertise of your doctors or all the information your doctors hold on your medical condition(s) or any additional factors that could affect your report results.

Let us first start with:

Atrial-sensed ventricular-paced rhythm is used when the patient has a good sinus node function but poor or no AV node conduction.  Your biventricular pacemaker will sense your natural atrial pacemaker and transmit the signals to the ventricles, since normal AV conduction is lost.

Biventricular pacemaker detected =  biventricular pacing confirmed, where stimulation occurs in both the right and left ventricle to help synchronise the ventricular contractions and to try to prevent or to improve heart failure symptoms. 

I note they mention your ventricular rate has increased by 11 bpm when compared with ECG of 3rd March 2021.  You could ask your doctors what the significance of this increase is?  Also, your ventricular/atrial resting rates seem fairly high at just under 80 bpm.  You could ask about this too: 

Ventricular Rate 79 BPM - see comment above
Atrial Rate 79 BPM - see comment above

P-R Interval 148 ms.  Normal range 120-200 mille seconds, see link for more info.  


QRS Duration 144ms.  The QRS duration in the presence of LBBB (left bundle branch block) may be expected to be within the range of 120 to 150 ms

Your QRS duration 144 ms is long but as mentioned earlier, in the presence of a complete bundle branch block - diagnosed when QRS duration is more than 120 ms - a QRS of 144 ms would not be unusual.  CRT benefits may take longer to be seen in some patients than in others, and this can be perfectly normal.

See links below:



QT 420ms. Your range is okay. See link for further info:


QT(C) 481 ms = QT Corrected:  estimates the QT interval at a standard heart rate of 60 bpm.  

P Axis 41 degrees
R Axis 154 degrees
T Axis 112 degrees

P Axis 41 degrees is normal - range 0 degrees to + 75 degrees

R Axis 154 degrees appears abnormal - range -30 degrees to + 90 degrees.  

T Axis 112 degrees, slightly above normal range which should be less than 105 degrees.

Have a look at the link on Axis for more info and also to read about causes for Axis Deviation.  

See link below:


Another helpful link:


Normal sinus rhythm - you could ask whether you are in normal sinus rhythm most of the time?

Looking at these figures on the whole, they wouldn't alarm me, especially with LBBB and AV Node block which may change the appearance of your ECG as can biventricular pacing.  You could ask your doctors if there are any concerns about the condition of your heart, whether there are any signs of any arrhythmias, any heart abnormalities in the heart’s shape and size, any signs that the heart is working harder than normal to pump blood although you would probably know by your symptoms if this were to be the case.

I see you don’t take any meds and appear to have no current health problems other than diagnosed electrical disturbances of the heart:  left bundle branch block, AV node conduction block, for which you have a CRT pacemaker.  

Conduction problems can cause ventricular standstill, though I see ventricular standstill can occur in their absence too.  I note you don’t seem to have any structural heart problems or signs of heart failure but I would seek confirmation of this?  I note you had extensive investigations to rule out other treatable causes for your intermittent ventricular standstill episodes but found none.  This should give reassurance that your CRT pacemaker alone may be all that will be necessary to support you in the future.  

Does that help a little?  I hope so.

Kindergarten vs college

by Lavender - 2022-07-21 17:59:55

Oh my, Gemita! I'm so appreciative of your extensive research and comments!  I'm feeling like a kindergarten kid listening to a college grad. I'm learning though, much of it is from sitting at your feet, so to speak and reading your comments to all here!

I read your links provided and got a lot out of it. Understanding my condition better is a comfort. All you said makes sense. No one has ever taken the time to investigate and explain all that to me. Not knowing can cause more anxiety-knowledge is power.

I did relook at my cardiologist notes after last June's echocardiogram :

 Normal left ventricular size. The left ventricle has normal systolic function. The estimated left ventricular ejection fraction is 55-60%. Abnormal septal motion consistent with abnormal electrical activation. Normal right ventricle size. The right ventricle has normal function. No significant valve disease. Normal diastolic function. No pericardial effusion. Catheters consistent with dual chamber pacemaker leads seen in the right ventricle and right atrium. As compared to 2/15/21: LV systolic function has improved.

I think all is ok structurally as can be--as per her notes and words to me. From your links, I got the idea that perhaps another note my cardiologist made (there is mitral annular calcification) shows a possible cause for the AV block. This mitral annular calcification is part of aging. One of your links says:  calcification of the annulus can inhibit electrical conduction of the AV node, consequently causing various degrees of heart block. While MAC does not usually necessitate treatment independently, the degree of calcification present in the annulus is an important factor in choosing the most appropriate treatment modality for several conditions that do require intervention.

When my pacemaker was put in, I asked the EP team what caused the AV node block. He said it was aging. 

When I was diagnosed with left bundle branch block, it was an accidental find. The LBBB came and went as it was flickering out over the next years. 

I am in normal sinus rhythm. The QRS duration is noted to be long in the prescence of LBBB as it says in your links. 

I am grateful to have no other medical issues and not be on any meds except for Vit D3. It's as cloudy here as in the UK lol. 

Many thanks and cyber hugs for all the intense detailed work you do here in serving all we who follow you on the path! It's your gentle wisdom that comforts and carries along so many-more than you will ever know! One indicator is looking at the "views" these posts get on this site. It's not uncommon to have 50-100 or more views on a given post in days and hundreds of views in weeks. So many people are learning. 
I am eternally grateful 🥹 💓☮️😘

Wide QRS

by FG - 2022-07-22 09:37:50

Doesn't a dual chamber (RA and RV electrode) PM firing always result in a wide QRS? I found this site. It's technical but highly detailed. Lots of content, search around!





Thank you, FG😃

by Lavender - 2022-07-22 10:27:41

Those links provide a lot of insight! I also was reminded that I was told that I had T wave inversion several years ago. Reading those links showed me that I had classic conduction disease progression. 

I am in awe of how our devices buy us time. The heart is so complex! I recall reading that the first pacemaker was made from a cat food can. My pacemaker tech still calls it "the can." 


by FG - 2022-07-22 10:54:46

Yes it is also fabulously amazing and complex. And when you get a condition like this, like I say I don't have mine yet but I'm preparing myself… My implant date is 8/23.


Yes it is fabulously amazing and complex. And when you get a condition like this, like I say I don't have mine yet but I'm preparing myself… My implant date is 8/23.


In high school I learned a saying by none other than Benjamin Franklin: 'the key to a long and satisfying life is to get yourself a chronic illness and take very good care of it". Now how about that! 

Understanding our condition is an important part of any treatment

by Gemita - 2022-07-23 06:29:14

Oh Lavender, what praise indeed.  Thank you so much.  All I ever set out to do was to try to reassure you that all was probably fine with your heart.  You have certainly reassured me that this is the case with some very healthy notes received from your cardiologist following your last echo.   

I agree the not knowing is what causes us to imagine the worse, but all these electrical faults are a real study and challenge for most of us, unless we are electrophysiologists.  I can understand it is difficult for them to start to engage with us in a manner that we could understand and why when we ask them what was seen, it will be easier for them to say “nothing to worry about” which just causes more confusion, more stress, more doubt that they are not telling us the “whole story”. This is especially true if we notice our hearts are intermittently racing, irregularly beating, pausing, slowing down or causing symptoms like breathlessness, dizzy spells or faintness.  If we can understand more about our condition, we will be able to have that meaningful conversation with our doctors and come away from our consultations feeling reassured and enlightened.  As you say, a little learning goes a long way and it is good to have each other to consult.

I also have mitral annular calcification (MAC) which was seen again yesterday during echocardiography, but technician said it hadn’t progressed since my last echo in 2017.  As you say importance of this finding will depend on “the degree of calcification present”.  It seems more prevalent in females.  You might care to read the “mechanism of Mitral Annular Calcification” link below.  It is interesting, but please don’t read more into it than you need to.  MAC seems to be common as we age and usually not worrisome if we can maintain a healthy lifestyle and the degree of MAC is minimal.


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