A Computer Model for In Silico Trials on Pacemaker Energy Efficiency

Pacemakers are commonly required to treat bradycardia. They are composed of a pulse generator and leads implanted in the heart, and deliver an electrical pulse so as to elicit cardiac contraction. The capture threshold (minimum energy required to stimulate the heart) is critical to assess and predict pacemaker performance. Indeed, the threshold may change due to fibrosis associated with the inflammatory process, resulting in loss-of-capture, requiring rehospitalization. We developed a 3D model that computes threshold curves depending on the pacemaker and cardiac tissue properties. Its credibility is being assessed by verification and validation in the context of capture threshold measurements on animal hearts. It aims to assist device companies in the early development phase of new lead designs. Here, it is used to compute the proportion of a population for which the initial device setting no longer captures, based on user-defined lead geometric and electric properties and population statistics. As a proof of concept, we compare the performance of MicroPort's VEGA™ lead and a custom one. The results show that the new design decreases the threshold to capture in one over three tested pulse durations, which is an improvement, but achieves poorer performance after the onset of fibrosis.