Surface mapping of RS-T segment in acute myocardial infarction.

Abstract

A method of surface mapping of the RS-T segment deviations that occur in acute myocardial infarction is described. The results observed in i5 patients are recorded and the potential value of this procedure is discussed in (i) diagnosis of myocardial infarction; (ii) delineating the extent of the myocardial ischaemia; and particularly (iii) its use as a method of examining the effect of therapies on the extent of myocardial ischaemia.Body surface iso-potential maps of the QRS have been reported in normal adults (Taccardi, I963), children (Spach et al., I966), and infants (Tazawa and Yoshimoto, I969), and in a number of cardiac disorders (Blumenschein et al., I968; Karsh, Spach, and Barr, I970). In experimental myocardial infarction in dogs, the area of the RS-T segment deviation in the epicardial leads has been used to represent the area of ischaemic myocardium (Rakita et al., 1954; Katcher, Peirce, and Sayen, I960; Sayen et al., I958; Braunwald et al., I969). It seemed probable that in man surface mapping of the RS-T segment deviations on the chest wall would reflect in some measure the underlying epicardial changes and perhaps define the position and extent of the myocardial infarction to a greater degree than the routine electrocardiogram.It is the purpose of this paper to describe a method and give the results of surface mapping of the RS-T segment deviations that were observed in a series of cases of proven myocardial infarction. MethodsFifteen patients who were admitted to the coronary care unit in the Hammersmith Hospital with a clinical diagnosis of acute myocardial infarction were studied. All but one had electrocardiographic evidence of acute myocardial infarction on the standard I4 lead electrocardiogram (including V4R and V7) and all had a transient diagnostic rise in serum enzymes.Electrocardiograms were recorded using a direct writing ink jet apparatus (Mingograph Elema-Schonander) recording on the three channels simultaneously. The electrodes used were the Welsh self-retained type with a contact diameter of i cm. In order to avoid spread of potentials the electrode jelly was applied only over a small area and the electrodes were carefully separated. The gain employed was I0 mm for I m volt and the paper speed was 25 mm/sec.The praecordial electrocardiograms used for surface mapping were recorded with the patient in the supine position and recorded daily for the first 7 days after the onset of symptoms and subsequently every few days during the patient's stay in hospital. In a few patients further electrocardiograms were recorded from 2 to 7 weeks later. These electrocardiograms were recorded from 72 points, distributed evenly throughout an area which extended from the mid-clavicular line on the right to the mid-axillary line on the left and from a line drawn horizontally through the angle of Louis to a line drawn horizontally through a point 6 cm below the xiphisternum (Fig. I). These points, which were 3 to 4 cm apart, were marked with a skin pencil so that all subsequent electrocardiograms were...

Nicardipine in models of myocardial infarction.

“…According to Reid et al (1971), ECG mapping techniques in patients allow the natural history of acute myocardial infarction to be followed. Similar observations have been made epicardially in dogs subjected to acute coronary artery occlusion (Hillis et al, 1976a, b).…”

The effects of shock energy, propranolol, and verapamil on cardiac damage caused by transthoracic countershock.

“…In the precordial leads recorded at a paper speed of 25 mm/sec, ST-T segment elevation was measured as the deviation of ST-T from the isoelectric TP segment of the trace 60 msec after the nadir of the S wave. 15 Continuous recordings of lead II of the ECG, heart rate (Devices Ltd.), and mean arterial blood pressure were made at a slow paper speed before and for 1 hr after application of the shocks.…”

Relationship between epicardial ST-segment elevation and myocardial ischemic damage after experimental coronary artery occlusion in dogs.

“…In addition, they found a good linear correlation between the miagnitude of ST-segment elevation 15 min after coronary arterv branch occlusion, and the extent of mvocardial creatine phosphokinase (CPK) enzyme depletion or the degree of histological disorganization 24 h later (7)(8)(9). These observations have formed the basis for the mapping of precordial ST-segment elevation as a method to measure extensions and reductions in the size of evolving clinical infarcts (10)(11)(12)(13). In contrast, our own studies (14) and those of Cohen and Kirk in dogs (15) did not reveal a simple quantitative relationship between epicardial ST-segment elevation and the regional myocardial blood flow (MBF) at 15 min after experimental coronary occlusion.…”