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Assume that the heart is beating, but no pacemaker cells are working for at least 15 seconds. This would be a very long compensatory pause if extrasystole started it. There may be some low frequent cells working at lower frequency (less than 10 Hz) but I do not understand what.

What is the name of condition where main pacemaker cells are not beating? Main pacemakers are SA-node, AV-node and Purkinje-fibers/His-bundle.

Raoul is correct. This is called asystole. It is temporal in the above case.

My definition in research but note the difference to current Clinics so you do not get confused: Asystole is a state of no cardiac electrical activity from pacemaker cells when the conduction system and cardiomyocytes can be still functioning (so the case in my thread). The conduction system and cardiomyocytes of the ventricles are responsible for the bradycardia in my case for short-term.

What do you think about this case? Some bradycardia? Can you suspect asystole there between?

enter image description here

Please, do not make diagnoses based on just this picture (which is often the current standard). Assume case where you see Time-Frequency of the heart perfectly and where you can see exactly the functioning of pacemaker cells at different frequency levels.

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  • $\begingroup$ Masi I have edited the question title which was confusing, please feel free to roll back $\endgroup$
    – One Face
    Jan 21, 2015 at 23:28

2 Answers 2

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If there are no pacemaker cells active, no muscle contraction will occur. This condition is named asystole. It can be a temporary or definitive condition. Some would call it "extreme bradycardia" in temporary cases, but this is just an euphemism.

Edit:

Ok, so let's try to clear up the confusion a bit. Technically, there is no asystole involved here (not even temporary). This rhythm is regularly irregular (irregular, but has a pattern), while asystole has no pattern by its very nature.

What you are seeing here is not the consequence of low frequency firing from pacemaker cells. The supraventricular extrasystoles (every 3rd QRS complex) are a consequence of early ventricular depolarization not triggered by SA node activity. The P wave that would normally trigger the 3rd complex does in fact occur, but it is synchronous with the abnormal QRS complex, which is why you cannot see it. The compensatory pause is due to lengthening of the hyperpolarized state in pacemaker cells, and is a consequence of the addition of the hidden P wave and the extrasystole in a short time.

In conclusion, this pattern is not the result of delayed pacemaker firing, but of early depolarization of cardiomyocytes by an accessory pacemaker.

strip with refractory time interval

I have marked on this strip the maximal time interval of SA node hyperpolarization. Depending on when the P wave hidden in the extrasystole occurs, the real time may be shorter than the above interval.

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  • $\begingroup$ Thank you for your fast answer! You are right. It is temporal asystole. I added a case picture which I think is little bradycardia and suspect asystole. What do you think? $\endgroup$
    – Léo Léopold Hertz 준영
    Oct 25, 2014 at 16:54
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    $\begingroup$ As you can see, there are 12 QRS complexes on this 14 sec. time interval, which yields a ventricular frequency of 51/min. This is termed bradycardia. Furthermore, every third complex has an altered signal, is not preceded by a P wave, and is followed by a compensatory pause. Those complexes are supraventricular extrasystoles, and the rhythm on this strip is termed "trigeminism". $\endgroup$
    – Raoul
    Oct 25, 2014 at 17:03
  • $\begingroup$ I think the case is extreme bradycardia and asystole. What can give frequencies of 5 Hz for 10 seconds? Probably something starts to excite when bradycardia reaches its maximum at 3s (first missing P wave). $\endgroup$
    – Léo Léopold Hertz 준영
    Oct 25, 2014 at 17:07
  • $\begingroup$ I suggest that you read a bit on supraventricular arrhythmias, and especially trigeminism. $\endgroup$
    – Raoul
    Oct 25, 2014 at 17:10
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    $\begingroup$ On the above strip, the inactivation (hyperpolarization) of the main pacemaker (the SA node) starts on the 3rd P wave (hidden in the abnormal QRS complex) and ends on the subsequent P wave, triggering a new (normal) QRS complex. If the pacemaker did not work for 10 seconds, you would have either an escape rhythm than can be junctional (SA node inactivation only), ventricular (SA & AV node inactivation), or a 10 second asystole. This is not apparent on this strip. Here, the inactivation can be estimated to be 1.4 sec. at most. $\endgroup$
    – Raoul
    Oct 26, 2014 at 16:53
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Bradycardia is a heart rate under 60 beats per minute. Your strip shows a heart rate of ~54 BPM (so, yes, it's bradycardia), and the rhythm is trigeminy. There is no asystole involved.

In the following rhythm strip, initially it shows supraventricular tachycardia (of >150 BPM). After adenosine administration, a short period of asystole occurs, allowing the SA node to resume it's normal pacemaker rhythm., then resumption of sinus rhythm (at just under 100 BPM). Notice there are **no electrical complexes) during the asystole. It's not a matter different guidelines. There is no asystole in your rhythm strip.

rhythm strip showing tachycardia, a short period of asystole after adenosine administration, then resumption of sinus rhythm.

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  • $\begingroup$ How can you say that there is no asystole involved? Do you have evidence? $\endgroup$
    – Léo Léopold Hertz 준영
    Oct 25, 2014 at 20:06
  • $\begingroup$ Ok, I am doing research here. In clinics,only clear asystole can be detected. I am trying to detect asymptomatic asystoles which occur only short time. $\endgroup$
    – Léo Léopold Hertz 준영
    Oct 25, 2014 at 20:34
  • $\begingroup$ Please read about event-triggered cardiac monitoring. $\endgroup$
    – anongoodnurse
    Oct 25, 2014 at 20:34
  • $\begingroup$ I know Holter but it is very cumbersome and errorprone, even single important beat can be missed. Current approach in clinics tries to take bigger sample of data - this is ok with current imaging technology, but requires much resources. 48h Holter is now standard. I am researching cardiograms and developing their imaging technologies. I can propose that the case has partial asystole with pacemakers of extremely low frequency active (not even Purkinje/His fibers). And this is confusing me, since I do not understand what can cause so low frequency. $\endgroup$
    – Léo Léopold Hertz 준영
    Oct 25, 2014 at 20:43
  • $\begingroup$ This is what electrophysiology is all about. Event triggered monitoring can be for 30 days, is different from Holter. $\endgroup$
    – anongoodnurse
    Oct 25, 2014 at 20:52

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