Recording of surface His-Purkinje potentials

The movement of the activation front in the His-Purkinje system determines the shape of the intracardiac recorded triphasic wave, but has little influence upon the shape of the surface signal. The unfiltered surface signal shows a step at the moment the His-bundle is activated by the av-node. The spike recorded by many investigators is probably the result of high-pass filtening of this step. To lessen the influence of the direction of the activity in the heart upon the shape of the recorded signal, registration of the two dimensional surface field is proposed. The transverse and longitudinal components of the surface field are recorded and used to compute the magnitude of the surface field as a function of time, irrespective of direction. In patients with a short PQ-time, discrimination between the end of the P-wave and the beginning of the HPS-wave can be problematic, especially when these signals overlap. In these cases, use can be made of the method introduced in a previous study, for the separation and suppression of the P-wave in the ECG. An improvement of this method will be discussed.