title: Dynamic changes of the QRS complex in unstable angina pectoris.
abstract: Despite intensive medical treatment to control chest pain, about one-third of patients with unstable angina have an unfavourable outcome within a period of 1 to 2 months. Holter monitoring can identify patients with silent myocardial ischaemia that are at a high risk of sustaining a major cardiovascular event. The present paper describes the use of dynamic, continuous, computerized on-line vectorcardiography for real-time monitoring of QRS-complex and ST-segment changes in patients with unstable coronary disease. In many patients a pattern of frequent repetitive episodes of QRS change was observed, with or without concomitant ST change. Whereas no patient had episodes of ST-vector change without also having episodes of significant QRS change, 15 patients had several episodes of QRS changes without any episode of significant ST change. The number of episodes of significant increase of the QRS vector difference correlated weakly but significantly with the number of episodes of significant ST-vector magnitude change (r = 0.34, p less than 0.05). The present study suggests that myocardial ischaemia will influence the QRS complex as well as the ST segment. The mechanism behind the QRS changes observed is not clear but episodes of QRS change without ST change or chest pain, may reflect sudden depressions of left ventricular function, as has been reported by others to occur in patients with coronary artery disease. Dynamic vectorcardiography offers the opportunity to monitor all parts of the QRST complex in real time.
authors.affiliation: Department of Medicine, University of Göteborg, Ostra Hospital, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Dellborg
authors.forename: G
authors.initials: G
authors.lastname: Gustafsson
authors.forename: M
authors.initials: M
authors.lastname: Riha
authors.forename: K
authors.initials: K
authors.lastname: Swedberg
mesh_terms: D000328:Adult; D000368:Aged; D000789:Angina, Unstable / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy; D015906:Angioplasty, Balloon, Coronary; D017023:Coronary Angiography; D001026:Coronary Artery Bypass; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis; D014672:Vectorcardiography