Clinical Resources

Vereckei aVR Algorithm

Wide Complex Tachycardia Differentiation — aVR Lead Algorithm

Step 1

Is there an initial R wave in lead aVR?

Step 2

Is there an initial r or q wave > 40 ms in lead aVR?

Step 3

Is there a notch on the descending limb of the initial dominant negative deflection in aVR?

Step 4

Calculate the vi/vt ratio: voltage change in the first 40 ms (vi) ÷ voltage change in the last 40 ms (vt) of the QRS complex.

vi — first 40 ms voltage (mV)

vt — last 40 ms voltage (mV)

Measure absolute voltage changes (magnitudes) in the initial and terminal 40 ms of the QRS in lead aVR.

Result

Diagnosis —

Determined at —

Answer Step 1 to begin the algorithm.

Reference

Vereckei A et al. New algorithm using only lead aVR for differential diagnosis of wide QRS complex tachycardia. Heart Rhythm. 2008;5(1):89-98

Algorithm Summary

This 4-step algorithm uses only lead aVR to differentiate ventricular tachycardia (VT) from supraventricular tachycardia (SVT) with aberrant conduction. Sensitivity 96.5%, specificity 75.0% for VT. When uncertain, treat as VT — it is the safer assumption.