Wenckebach Pattern of Ventricular Late Potentials

Abstract

Ventricular late potentials are considered a marker of an arrhythmogenic substrate especially in patients with a history of myocardial infarction. The classic way of late potential analysis, the vector analysis in the time domain, the so called Simson method, is useful in the post-infarction risk stratification with its great ability to predict a very low risk when the results are normal. However, the positive prediction is only poor, especially of ventricular fibrillation and sudden cardiac death rather than the prediction of sustained, slow, monomorphic and reproducibly inducible ventricular tachycardia [1].

Up to now recording of late potentials from the body surface, signals in the range of microvolts, requires the application of signal averaging techniques in order to improve the signal-to-noise ratio [2]. However, the primary shortcoming of these methods is that they do not allow the recognition of dynamic variations that may occur on a beat-by-beat basis.

Invasive registrations have shown that in ischemic regions of a postinfarction heart, the origin of late potentials, activation patterns sometimes varied with successive sinus beats. In certain areas 2:1 or Wenckebach like conduction patterns were observed. In canine models it has been demonstrated that the presence of these conduction sequences represent the possibility of initiating a reentrant rhythm rather than the presence of a conduction delay following the regular 1:1 pattern [3].

Since these dynamics are not amenable to signal-averaging techniques but theoretically can be represented on the body surface in a beat-to-beat fashion, methods for single-beat late potential analysis both in the time and the frequency domain have been developed.