An experimental model of giant negative T wave associated with QT prolongation produced by combined effect of calcium and isoproterenol.

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Abstract
Changes of the surface ECG and monophasic action potential induced by isoproterenol injection were investigated under normo- and hypercalcemic conditions in dogs. Biphasic time course of T wave changes, initially inverted and subsequently uprightly tall, was observed after i.v. injection of isoproterenol in doses of > 2 .mu.g. Initial prolongation and subsequent shortening of the phase 2 of action potential were observed on the ventricular surface in accordance with the biphasic time course of the T wave changes on the surface ECG after isoproterenol injection. Giant T wave inversion associated with QT prolongation was obtained by isoproterenol injection under hypercalcemia. Marked prolongation of total duration and phase 2 of action potential was observed in accordance with the giant negative T wave on the surface ECG. Although the mechanism of this experimental model of giant negative T wave is not clear, this model could have important suggestions on the unknown mechanism of giant negative T wave observed in various clinical status.