Sinus Arrhythmia

Creado por team@ekgdx.com el 22 de Enero de 2023

Let’s talk about sinus arrhythmia.

Sinus arrhythmia is the presence of changing sinus rhythm with varying P-P intervals and constant PR interval. 

Criteria

  • Normal sinus P waves.
  • Varying P-P intervals. 
  • The longest and shortest P-P intervals vary by ≥0.16 sec or ≥10%. 
  • PR interval remains constant. 

There are three types of sinus arrhythmia:

  1. Respiratory-Phasic: Sinus rate increases with inspiration and decreases with expiration.
  2. Nonrespiratory: Sinus rate varies unrelated to respiratory cycle.
  3. Ventriculophasic: Commonly seen in patients with second degree or third degree AV block when the P-P interval containing the QRS complex is relatively shorter compared to the P-P interval without the QRS complex.

Possible causes:

  • Respiratory-Phasic: May be a normal finding in young individuals or with increased vagal tone.
  • Nonrespiratory: Can be seen in a traumatic intracerebral hemorrhage with associated vasospasm, hypoxia or increased intracranial pressure.
  • Ventriculophasic: Can be seen in a second degree or third degree AV block. 

The proposed mechanisms for ventriculophasic sinus arrhythmia are:

  1. Reflex baroreceptor-mediated phasic changes in vagal tone.
  2. Mechanical effect of pressure changes caused by ventricular systole.
  3. Increased ventricular filling during the long sinus cycle with increased blood flow to the sinus node during ventricular systole.

respiratory sinus arrhythmia - EKGDX

Respiratory sinus arrhythmia

 

ventriculophasic sinus arrhythmia - EKGDX

Ventriculophasic sinus arrhythmia: Note that the PP interval containing the QRS is shorter than the PP interval without the QRS, in the setting of 2:1 AV block

 

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References

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Dr. Roig

Sinus Arrhythmia