[Definition of ventricular tachycardia]

The definition of ventricular tachycardia, clear in principle as it consists of tachycardias arising from the ventricular mass and therefore distal to the bifurcation of the His bundle, is not as simple on clinical practice. When the QRS complexes are wide, the rate of the arrhythmia and its active or passive characteristics are not so clear-cut. The number of beats justifying the term tachycardia, the classification as simple or complex, become affairs of conventions, which may change with the evolution of concepts and improved understanding of the electrophysiological mechanisms. A certain flexibility in the usage of terminology should follow the evolution of ideas.