Computers in Biology and Medicine 35 (2005) 299 – 309 http://www.intl.elsevierhealth.com/journals/cobm Changes in the slope of the rst major deection of the ECG complex during acute coronary occlusion Guy Dori a; c ; * , Arie Rosenthal a , Shmuel Fishman d , Yaron Denekamp a; c , Basil S. Lewis b; c , Haim Bitterman a; c a Departments of Internal Medicine, The Lady Davis Carmel Medical Center, 7, Michal St., Haifa 34362, Israel b Department of Cardiology, The Lady Davis Carmel Medical Center, 7, Michal St., Haifa 34362, Israel c Faculties of Medicine, Technion, Israel Institute of Technology, Haifa, Israel d Faculties of Physics, Technion, Israel Institute of Technology, Haifa, Israel Received 15 September 2003; accepted 12 January 2004 Abstract To evaluate the eect of acute coronary occlusion (ACO) during percutaneous coronary intervention (PCI) on the slope of the rst major deection of the QRS complex (the initial QRS slope). Standard ECG signals of 18 patients (89 leads), undergoing PCI were recorded prior to and during ACO. The initial QRS slope was calculated in the baseline state and during ACO. Changes in the standard ECG were detected in 36 of 89 leads (40%). The initial QRS slope during ACO was signicantly dierent from baseline in 74 of 89 leads (83%). The specicity of the change in the slope during ACO was low (29%). ? 2004 Elsevier Ltd. All rights reserved. Keywords: ECG analysis; Myocardial ischemia; PCI; Electrophysiology 1. Background Ischemia causes partial depolarization of the membrane of resting myocardial cells, which in turn decreases conductivity of sodium channels in the cellular membrane, thereby decreases the rapid sodium inux. The latter accounts for phase 0 of the ventricular action potential (AP), which is related to the onset of the early part of the QRS complex of the surface ECG [1–3]. In addition, * Corresponding author. Department of Internal Medicine, The Lady Davis Carmel Medical Center, 7, Michal St., Haifa 34362, Israel. Tel.: +972-4-825-0484; fax: +972-4-826-0213. E-mail address: g dori@bezeqint.net (G. Dori). 0010-4825/$ - see front matter ? 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.compbiomed.2004.01.005