The 3 orthogonal lead electrocardiogram has been evaluated with computer assisted interpretation in 20 patients with acute pulmonary embolism confirmed by pulmenary angiography. Initial 3-lead electrCcardiographic abnormalities were found to be at least as helpful as the 12-lead electrocardiogram in supporting the clinical diagnosis. In addition, however, sequential changes in both the maximum QRS and T vector orientations in frontal and transverse planes were more often apparent than any sequential changes in the 12-lead electrocardiogram. While no specific 3 lead electrocardiographic criterion for pulmonary embolism could be determined, this technique was more helpful than conventional methods infollowing serial electrocardiographic changes in patients with this condition.The recent availability of pulmonary angiography x-ray, serial enzyme studies, full blood count and has facilitated a more critical appraisal of the 12 ESR. Patients were divided into two groups for purlead electrocardiographic appearances in acute poses of analysis. Group 1 consisted of 14 patients pulmonary embolism than has hitherto been pos-with no previous history of cardiac or respiratory sible (Stein et al., 1975). As far as is known, there disease. Group 2 consisted of 6 patients who had a have, however, been no studies to evaluate serial 3 significant cardiac or respiratory history which per se orthogonal lead electrocardiographic abnormalities had led to the development of an abnormal electroin patients with acute pulmonary embolism proven cardiogram. The details of age, sex, duration of angiographically. With the recent availability of a symptoms before presentation, together with the routinely used computer programme for storing underlying diagnosis are shown for groups 1 and 2 orthogonal lead data to enable comment on day-to-in Tables 1 and 2, respectively. day electrocardiographic changes to be made Pulmonary angiography was performed in all cases. (Macfarlane, Cawood, and Lawrie, 1975), it was A 7 x 125 Gensini catheter was passed via a right decided to undertake a study of 3 orthogonal lead medial cubital vein into right atrium, right ven-(and corresponding 12 lead) electrocardiograms in tricle, and then into the main pulmonary artery. order to determine whether or not diagnostic Pressure measurements were taken in these three criteria for a positive electrocardiographic change sites. The catheter was then left in the main could be incorporated into the routinely used pulmonary artery and 45 to 55 ml (dose depending programme.on body weight) angiografin were then injected using a Girdlund H-P injector. The angiogram was Subjects and methods recorded on 35 x 35 cm film using an Elema Twenty patients (12 male and 8 female-mean age Schonander rapid film changer in conjunction with 52+13) were included in the study. In all cases a a high speed fine focus tube. Films were exposed at diagnosis of acute pulmonary embolism was sus-a rate of 4 per second for 4 seconds and thereafter pected on clinical grounds and confirmed by 1 per sec...
