Inverse solution of ST vector as a single unfixed location dipole in patients with acute myocardial infarction

For the quantitative assessment of infarct site and size in patients with acute myocardial infarction, an attempt was made to solve the inverse problem, that is, to characterize ST vector in the infarcted myocardium from ST segment deviations in 29 precordial leads and their sterical positions A simple inverse model was employed, assuming that the source origin of ST segment displacement in surface electrocardiograms was a single unfixed dipole embedded in the homogeneous infinite medium. The magnitude, direction and position of ST vector were calculated as an inverse solution by computer. The direction of ST vector determined by this inverse problem was well in accord with infarct site assessed by left ventriculography or myocardial scintigraphy carried out later. However, the magnitude of ST vector was poorly correlated (r = 0.47, p less than 0.005, n = 17) with infarct size estimated from serum creatine phosphokinase, although a good correlation (r = 0.74) was obtained when 3 cases with extremely large infarction were excluded. These results suggest that our inverse solution of ST vector is useful for prediction of the site and size of acute myocardial infarction.