Computer simulation of magnetic-field patterns from the human cardiac conduction system

Abstract

Invasive and noninvasive measurements of the electric and magnetic signals of the PR segment of the human cardiac cycle have been performed during the last decade. It is still questionable whether the detected signals are produced by the activity of the heart conduction system or by atrial repolarization. We present a computer simulation of the magnetic-field patterns generated by a model of the human-heart conduction system (His-Purkinje system, HPS) over the anterior chest wall. The model is based on a close correspondence with the anatomical features of the HPS and accounts for the common His bundle (HB) and the left bundle branch (LBB) only. Computed fields clearly indicate a “ramp” pattern, strongly depending on the position over the chest. The model provides also a spikelike signal at the beginning of the ramp corresponding in time to the propagation of the activation from the HB to the proximal LBB. Both features are in good agreement with results of experimental measurements, thus supporting the hypothesis that the detected field patterns originate from HPS activity. A qualitative comparison with an experimental magnetocardiographic map is also shown.