Daily precordial ST-segment mapping was performed with the millimeter sum of ST-segment deviation (ΣST) in a 48-lead system (1 mv = 20 mm) to evaluate 26 normal subjects and 19 patients with acute myocardial infarction. At the time of admission, ΣST (± S.D.)for transmural infarction (men + 140 ± 84.8, and women + 95.7 ± 8.8) and nontransmural infarction (-67 ± 32) was significantly different (p<0.001) from controls (men + 30.1 ± 18.1, and women + 17 ± 11.7). ΣST approached normal values by 10.6 and 13 hospital days, respectively. Twelve of 14 patients (86 per cent) with transmural infarction had re-elevation of ΣST ( + 76 ± 49.7) 5.8 days (mean) after admission. This finding was associated with abnormal creatine phosphokinase in eight (57 per cent), suggesting infarct extension. Standard six precordial leads did not reflect re-elevation of ΣST in four of the 12 patients with infarct extension. The 86 per cent incidence of infarct extension indicates that measures designed to decrease myocardial ischemia may be effective for many days after the onset of acute myocardial infarction. Multiple electrocardiographic leads applied to the epicardium in animals with myocardial infarction have been used to delineate the severity and extent of myocardial ischemia by summing the ST-segment elevation in the individual leads and determining the number of leads where elevation occurred.1 A depletion of myocardial creatine phosphokinase has been observed within the areas in which ST-segment elevation occurs after induced coronary occlusion in the canine model.1 These findings support the concept that the amount of ST-segment elevation that develops under these circumstances is directly related to the amount of myocardial ischemia or necrosis. Serial observations of precordial ST segments.
ASJC Scopus subject areas