Modeling the post-extrasystolic potentiation to determine heart failure

Introduction Premature ventricular contractions (PVC) occur naturally in the human heart and lead to a well-studied increase in cardiac contractility, referred to as post-extrasystolic potentiation (PESP), which behaves independently of many otherwise confounding factors. It is well-known that the degree of potentiation differs between healthy and failing hearts. In this paper, we present a method for non-invasive and non-obtrusive assessment of the PESP, leveraging photoplethysmography (PPG) measurements, revealing information on the degree of potentiation and thereby cardiac functioning. Methods We modeled the PESP as a second-order system and we compared the parameters of this system between patients with differing ejection fractions. The method was developed on an internal dataset acquired during percutaneous, electrophysiological procedures. The parameters of the proposed second-order system are determined for each of these patients and the results show a correlation between cardiac ejection fraction and the damping factor, one of the parameters of the system. Results This model-based approach was demonstrated on the earlier mentioned non-obtrusive PPG measurements, as well as invasive blood pressure measurements. Modeling the PESP as a second-order model using information obtained from the non-invasive PPG signal reveals information showing a promising step towards enabling continuous monitoring of cardiac contractility using non-invasive means. Discussion The presented method could be applied in non-invasive, non-obtrusive PPG recording devices such as a smartwatch. This provides a continuously monitored estimate of cardiac contractility as an additional clinical parameter, as well as decreasing the time between reduction of contractility and potential hospital admission.