Sinus Node Rhythms and Arrhythmias: Difference between revisions

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Please read the [[Introduction|introduction to the 7+2 step plan]] first.
Please read the [[Introduction|introduction to the 7+2 step plan]] first.


The sinus node (SA) is located in the roof of the right atrium. It is the fastest physiological pacemaker. When the sinus node generates an electrical impulse, the surrounding cells of the right atrium depolarise, then the cells of the left atrium, the AV (atrioventricular) node follows and at last the ventricles are stimulated via the His bundle.
The sinus node (SA) is located in the roof of the right atrium. It is the fastest physiological pacemaker. When the sinus node generates an electrical impulse, the surrounding cells of the right atrium depolarize. Then the cells of the left atrium, the AV (atrioventricular)node, follow, and at last the ventricles are stimulated via the His bundle.


<flashow>http://nl.ecgpedia.org/images/0/09/Normal_SR.swf|align=right|height=300px|width=300px</flashow>
<flashow>http://nl.ecgpedia.org/images/0/09/Normal_SR.swf|align=right|height=300px|width=300px</flashow>


With this knowledge it is quite simple to recognise normal sinus rhythm on the ECG.
With this knowledge it is quite simple to recognize normal sinus rhythm on the ECG.


{| class="wikitable"  
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*A [[P wave morphology]] P wave (atrial contraction) precedes every QRS complex
*A [[P wave morphology]] P wave (atrial contraction) precedes every QRS complex
*The rhythm is regular, but varies slightly while breathing
*The rhythm is regular, but varies slightly during respirations
*The rate ranges between 60 and 100 beats per minute
*The rate ranges between 60 and 100 beats per minute
*The P waves maximum height is 2.5 mm in II and/or III
*The P waves maximum height at 2.5 mm in II and/or III
*The P wave is positive in I and II, and biphasic in V1
*The P wave is positive in I and II, and biphasic in V1
|}
|}


As you see, at least knowledge of [[Rate|heart rate]] and [[P wave morphology]] are necessary to determine the rhythm. Still, we have put Rhythm as step 1 as it is of such importance in the interpretation of the ECG, as arrhythmias include the most lifethreatening ECG abnormalities. In most settings however, the rhythm will be sinus rhythm in the vast majority of ECGs.
As you can see, knowledge of [[Rate|heart rate]] and [[P wave morphology]] are necessary to determine the rhythm. We have put Rhythm as step 1 as it is of great importance. Arrhythmias include the most life-threatening ECG abnormalities. In most settings, however, the rhythm will be sinus.


If the rhythm is not sinus rhythm, the '''[[arrhythmias|arrhytmias algorithm]]''' should be followed.  
If the rhythm is not sinus, the '''[[arrhythmias|arrhytmias algorithm]]''' should be followed.  


==Sinus arrhythmias==
==Sinus arrhythmias==
Some variants of sinusrhythm exist:
Some variants of sinus rhythm exist:
*[[Asystole]]
*[[Asystole]]
*[[Sinustachycardia|Sinustachycardia (>100 beats per minute)]]
*[[Sinustachycardia|Sinustachycardia (>100 beats per minute)]]

Revision as of 17:39, 15 January 2010

«Basics Step 2: Heart Rate»


Author(s) J.S.S.G. de Jong
Moderator I.A.C. van der Bilt
Supervisor
some notes about authorship

Please read the introduction to the 7+2 step plan first.

The sinus node (SA) is located in the roof of the right atrium. It is the fastest physiological pacemaker. When the sinus node generates an electrical impulse, the surrounding cells of the right atrium depolarize. Then the cells of the left atrium, the AV (atrioventricular)node, follow, and at last the ventricles are stimulated via the His bundle.

<flashow>http://nl.ecgpedia.org/images/0/09/Normal_SR.swf%7Calign=right%7Cheight=300px%7Cwidth=300px</flashow>

With this knowledge it is quite simple to recognize normal sinus rhythm on the ECG.

Criteria for normal sinus rhythm (see also Basics):
  • A P wave morphology P wave (atrial contraction) precedes every QRS complex
  • The rhythm is regular, but varies slightly during respirations
  • The rate ranges between 60 and 100 beats per minute
  • The P waves maximum height at 2.5 mm in II and/or III
  • The P wave is positive in I and II, and biphasic in V1

As you can see, knowledge of heart rate and P wave morphology are necessary to determine the rhythm. We have put Rhythm as step 1 as it is of great importance. Arrhythmias include the most life-threatening ECG abnormalities. In most settings, however, the rhythm will be sinus.

If the rhythm is not sinus, the arrhytmias algorithm should be followed.

Sinus arrhythmias

Some variants of sinus rhythm exist:

Arrhythmias are discussed in the Arrhythmias chapter.

If the heart rate exceeds 100 bpm, the tachcyardia flow chart should be followed.

Examples

  • An example of normal sinus rhythm.

    An example of normal sinus rhythm.

  • Another example of normal sinus rhythm.

    Another example of normal sinus rhythm.


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