Stimulus to A Maneuver

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• Used to differentiate Atypical AVNRT from Septal Bypass Tract
• Measure Stimulus at onset of QRS on RV pacing channel to stimulus to A signal at HRA
• Calculate SA -VA interval
  • SA - VA interval > 85 for Atypical AVNRT. (range 90 - 200)
  • SA - VA interval < 85 for ORT using Septal Pathway (range 0-80)

Weaker of two rules comparing Ventricular Overdrive Maneuver versus Stimulus to A Maneuver because it only reflects retrograde conduction.

In the above example the Stimulus to A is 165 ms and the V to A is 110 ms. Thus the SA- VA equals 55 ms providing evidence that there is a septal pathway

References

Differentiation of Atypical Atrioventricular Node Re-Entrant Tachycardia From Orthodromic Reciprocating Tachycardia Using a Septal Accessory Pathway by the Response to Ventricular Pacing. J Am Coll Cardiol 2001;38:1163–7