A single-step criterion to differentiate ventricular tachycardia from supraventricular tachycardia with aberrancy. Measure the R-wave peak time in lead II.
Step 1
Single step · lead II
In lead II, is the time from QRS onset to the first change in polarity ≥ 50 ms?
Measure from QRS onset to the peak of the first R wave or, in a predominantly negative complex, to the nadir of the first S wave.
A standalone ECG criterion. A time < 50 ms does not rule out ventricular tachycardia; interpret it together with the other findings and the clinical context. When in doubt in a wide QRS tachycardia, the safe approach is to assume VT.
A tool to support learning and decision-making. The result does not replace clinical evaluation of the patient.
About: Pava algorithm
The Pava criterion uses a single measurement to differentiate VT from SVT with aberrancy: the R-wave peak time in lead II.
In VT, activation starts outside the conduction system and spreads slowly, so the first QRS deflection takes longer to reach its peak.
How to use
Choose a well-defined complex in lead II.
Measure from QRS onset to the peak of the first R wave or, if the complex is predominantly negative, to the nadir of the first S wave.
Compare with the 50 ms cutoff.
How to interpret
Time ≥ 50 ms: positive criterion, favors ventricular tachycardia.
Time < 50 ms: favors SVT with aberrancy but does not rule out VT.
Limitations
Wide QRS tachycardia algorithms were derived in selected populations and lose accuracy in the hands of infrequent users. No result safely rules out ventricular tachycardia: when in doubt, or if the patient is unstable, manage as VT. Because it is a standalone criterion, interpret it together with the other findings and the clinical context.
References
Pava LF, Perafán P, Badiel M, et al. R-wave peak time at DII: a new criterion for differentiating between wide complex QRS tachycardias. Heart Rhythm. 2010;7(7):922–6.
