English

Abstract

The impedance cardiogram (ICG) is a promising tool for non-invasive and cost effective assessment of the hemodynamic state, especially in low acuity and home settings. Important diagnostic parameters are related to characteristic points within the ICG, i.e. the B and the X points that are assumed to mark the opening and closure of the aortic valve., respectively. Based on synchronized echocardiography-ICG data obtained from healthy subjects at rest, we compare 4 existing alternatives for the ICG’s characteristic point definitions associated detection algorithms. We show that those points exhibit considerable biases with respect to the intended onsets of the systole and diastole compared to the Echocardiography Goldstandard. We introduce a new approach to determine these characteristic points based on the analysis of the ICG morphology. For its implementation a computationally simple algorithm, based on high order derivatives, is proposed. This algorithm is evaluated using simultaneously recorded echocardiographies and ICG signals. The achieved results show that the proposed method enables the identification of the main characteristic points, B and X, with significantly smaller errors and much higher correlations compared to current state of the art methods and existing alternative characteristic point definitions.