Evaluation of a new modified chest lead in diagnosing wide-complex beats of unknown origin

Abstract

Background: Simulation of electrical activation of the heart and its comparison with real activation is a promising method in testing potential determinants of excitation events in the heart. The need for simulation of the electrical activity of the human heart is now emerging as a step forward for understanding and predicting electrophysiological patterns in humans. Initial points of excitation and the manner in which the activation spreads from these points are important variables determining QRS complex characteristics. It was suggested that in humans, the initial excitation of the left ventricle is primary determinant of QRS complex characteristics, and it begins at the papillary muscles and septum, where the fascicles of the left bundle branch insert. The aim of this study is to test the hypothesis that QRS duration and direction of QRS axis in the frontal plane has excellent agreement between real QRS and simulated QRS using papillary muscle position as the origin of early ventricular activation. Methods: Fourteen healthy adult volunteers were included in the study. Magnetic resonance imaging (MRI) data were obtained to assess the papillary muscle positions. 12-Lead electrocardiographic (ECG) recordings were used to obtain real ECG for assessment of QRS duration and QRS axis in each subject. Simulation software developed by ECG-TECH Corp was used to simulate ECG of each subject and assess simulated QRS duration and QRS axis. Agreement between real and simulated QRS duration and QRS axis was calculated. Results: Seventy-nine percent of subjects had difference of the QRS duration between real and simulated ECG of less than 10 milliseconds. The calculated strength of agreement between simulated and real QRS duration was 71% and considered as ‘good’ (kappa statistics). In 70% of subjects, the difference in the QRS axis was less than 10 degrees. The calculated strength of agreement between simulated and real QRS axis was 80% and considered as ‘excellent’ (kappa statistics). Conclusions: The results suggest the sites of the initiation of electrical activity in the left ventricle, as assessed by the positions of papillary muscles, may be considered as primary determinants of the QRS duration and QRS axis in the humans. This knowledge may help in predicting normal QRS characteristic on a patient-specific basis. This is the first study where simulation of the QRS complex was based on anatomical data from the human hearts.