Analyzing ventricular late potentials using a vector magnitude function

Approaches to analyzing ventricular late potentials (VLP) have in general been limited to an examination of the vector magnitude of three orthogonal lead signal averages. This study investigates the errors that can arise in detecting VLP from the vector magnitude (VM) in the presence of residual noise after signal averaging. The results from a simulation and a preliminary clinical study suggest that the latest moment of ventricular activation, i.e., the QRS offset, is consistently underestimated in the VM. This implies that VLP may not be detected consistently on the basis of measured QRS duration.<>