Projection of electrocardiographic signs in praecordial maps after exercise in patients with ischaemic heart disease.

Abstract

suMMARY Praecordial surface maps of the electrocardiogram were recorded before and after exercise using 16 electrodes covering the left hemithorax. The ST segment and R and S wave changes were measured in the praecordial maps from 20 individuals with no detectable cardiovascular disease. These showed no significant alteration in ST segments or R/S. In contrast in 40 patients with angiocardiographically proven coronary artery disease it was possible clearly to outline the distribution, severity, and time course of praecordial areas of ST segment depression (36 patients) and ST segment elevation (10 patients). In addition these praecordial areas of ST segment changes were accompanied by a regional and significant fall in the R/S.The praecordial electrocardiogram with exercise complements the anatomical information obtained from the coronary arteriogram by clearly outlining electrocardiographic projections of regional myo--cardial ischaemia or cell death.The exercise electrocardiogram has long been used in the diagnosis and evaluation of patients with coronary artery disease (Bruce and McDonough, 1969;Sheffield and Roitman, 1975;Blackburn, 1977). Interest has centred on ST segment changes on exercise (Roitman et al., 1970;Redwood et al., 1977) though in recent years changes in the QRS vector have been described (Kilpatrick, 1976). Though the praecordial electrocardiogram using 36 to 72 leads is being used to study the natural history of acute myocardial infarction and the effect of interventions (Maroko et al., 1972;Selwyn et al., 1977a;Selwyn and Shillingford, 1977), this technique has not been widely applied to the exercise electrocardiogram. This is the result of difficulties in recording the surface electrocardiogram before transient changes have regressed and in designing an adequate electrode system which is stable during severe exertion. In a recent study, a technique for recording the praecordial electrocardiogram, using conventional equipment available in most hospitals, has been described (Fox et al., 1978). The purpose of the present study is to describe the variety of praecordial electrocardiographic abnormalities that occur on exercise.'This work was supported by a grant from the British Heart Foundation and Welcome Trust.Received for publication 13 February 1979 Methods Twenty normal male volunteers (aged 28 to 74, mean 52 years) and 40 consecutive male patients (aged 32 to 72, mean 54 years) with a typical history of angina pectoris, ST segment changes after exercise, and anatomical evidence of coronary artery disease shown by coronary arteriography were studied. Routine 12 lead electrocardiograms were recorded in all patients. All patients were in sinus rhythm at rest. Patients whose electrocardiograms showed abnormalities in the mean frontal axis (that is beyond -30°and + 120°) or QRS duration more than 110 ms before exercise were excluded from the study.Praecordial exercise electrocardiograms were recorded using a direct writing ink jet Mingograf (Elema-Schonander) recording on four channels si...

R wave amplitude during exercise. Relation to left ventricular function and coronary artery disease.

“…In a group ofpatients with significant but unspecified coronary artery disease, Fox et al 38 using erect bicycle exercise and praecordial surface mapping found a consistent decrease in R wave amplitude in patients with or without electrocardiographic evidence of ischaemia. The reasons for these opposite or less clear-cut findings may be related to differences in the patients under study, the type of exercise, posture during exercise, and the recording leads selected.…”

R-Wave Amplitude and Left Ventricular Volume: Changes with Nitroglycerine and Atrial Pacing

“…26]. Although the validity of this observation has been challenged [2,9,24], change in intracardiac volume is suggested as the single most likely mechanism (the 'Brody effect') based largely on mathematical theory and animal experimental studies (3, 8, 10, 12, 15. 17, 20, 22).…”