Analysis of T-wave abnormalities associated with myocardial infarction using a theoretic model

The physiological basis of serial T-wave abnormalities associated with myocardial infarction was studied. After coronary artery ligation in dogs, ventricular functional refractory periods (FRPs) were measured at five to eight epicardial, intramural, and en-docardial sites. FRPs measured during acute ischemia shortened an average of 26 msec. FRPs measured 24 to 72 hr after coronary ligation were 24 msec longer at is-chemic than at nonischemic sites. Alterations of recovery times were analyzed in terms of a repolarization model which related the form of the action potential downstroke to the form of the T wave of the body surface ECG. Observed FRPs were used to in-fer action potential duration and T waves were derived. Shortening FRPs in the antero-lateral wall of the ventricle increased the amplitude of derived T waves in the X lead and caused T-wave inversion in the Z lead. Prolonging FRPs in the same area caused T-wave inversion in lead X and increased T amplitude in lead Z. The form of derived T waves qualitatively corresponded to serial T-wave abnormalities seen in patients with myocardial infarction. Additional Indexing Words: T-wave model Transmembrane action potential form THE RECOGNITION of myocardial in-farction is one of the major diagnostic applications of the electrocardiogram. The physiological mechanisms of QRS abnornali-ties resulting from destruction of excitable tis-sue and alteration of intraventricular conduc-tion have been reasonably well defined, but the mechanism of ST-T-wave abnormalities is less completely understood. The recent de-velopment of a theoretic model of repolari