Definition

  Phasic change of the sinus rate in relation to the QRS complex.

  The PP interval containing the QRS complex is
shorter than the PP interval not encompassing it.



Where do we see it?

  In some patients with high degree AV block or complete AV block.

  In some patients with ventricularly paced rhythms.




Mechanism

  The exact mechanism is not known.

     
Suggested mechanisms:

  Ventricular contraction following the QRS complex increases blood flow to the baroreceptors

      which in turn affects the sinus rate through vagal stimulation.

  Ventricular contraction following the QRS complex increases blood flow to the sinus node

      which in turn increases the sinus rate.




Paradoxical Ventriculophasic Sinus Arrhythmia

  The PP interval containing the QRS complex is longer than the PP interval not encompassing it.

  Paradoxical ventriculophasic sinus arrhythmia is very rare.

  Mechanism is unknown.




References

  Circulation 1998;97:2245-2251.

  Cardiology 1970;55:65-8.

  Circulation 1955;11:240-61.

  Journal of Cardiology Cases 2011;3:e37-e39.

  Int J Cardiol 2003;91:71-74.





ECG 1. The ECG above is from a 6 months-old infant with non-restrictive type VSD. He has congenital 2:1 AV block.

Of every two P waves, only one can be conducted to the ventricles
. Also, the interval between the first P wave and
the second P wave
is shorter than the interval between the second P wave and the third P wave .

This is called as
VENTRICULOPHASIC SINUS ARRHYTHMIA . It is less pronounced on the left side of this ECG .

Pediatric cardiologist Dr. Mahmut Gokdemir has donated this ECG to our website.

Click here for a more detailed ECG





ECG 2. Wenkebach type 2:1 AV block. Narrow QRS complexes
suggest Mobitz Type 1, 2:1 AV block.
Of every two P waves
only one is conducted to the ventricles while the other is not .
The above ECG was recorded
at a calibration of 20 mm/mV to show the P waves more clearly.

Click here for a more detailed ECG





ECG 3. The above ECG is from a 67 years-old man and shows ventricular trigeminal rhythm with interpolated
VPCs.
The
PP interval containing the VPC is shorter than the PP interval not encompassing it.
Also, the first
PR interval following the VPC is relatively prolonged when compared with the preceding PR interval.

Click here for a more detailed ECG