title: Abnormalities of the S-T segment--Part I.
abstract: The usual normal S-T segment of the surface electrocardiogram (ECG) contributes little to the diagnostic procedure. When the S-T segment is too long or too short, or when it is displaced upward or downward, it is commonly abnormal. Under such circumstances, an S-T segment abnormality usually contributes considerable diagnostic information. When the Grant method of ECG interpretation is used, it is possible to perceive abnormalities of the S-T segment that may otherwise be ignored or misinterpreted. This paper describes the method of identification and the significance of primary and secondary S-T segment abnormalities. When a mean vector constructed for the S-T segment displacement seen in 12 ECG leads is relatively parallel with a mean vector representing the T wave, it is, with a few exceptions, part of the repolarization process and is therefore part of the T wave. This may be called a secondary S-T segment abnormality. When a mean vector constructed for the S-T segment displacement seen in 12 ECG leads is not relatively parallel with a mean vector representing the T wave, it is, with a few exceptions, not part of the repolarization process and is therefore not part of the T wave. This may be called a primary S-T segment abnormality.
authors.affiliation: Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Hurst
mesh_terms: D000328:Adult; D004562:Electrocardiography / Q000379:methods*; D006329:Heart Conduction System / Q000503:physiopathology; D006331:Heart Diseases / Q000175:diagnosis*; D006801:Humans; D008955:Models, Cardiovascular