Electrical alternans of the T-U wave without change in the QRS complex

A patient with myelocytic leukemia who showed electrical alternans of the T-U wave with no change in the QRS complex following chemotherapy is described. Electrocardiogram taken 4 days later showed ventricular quadrigeminy in which the T-U wave of the first sinus beat after the ventricular premature contraction was markedly less prominent compared to the successive two sinus beats which showed marked prolongation and inverted T-U waves. The causative factors for alternans of T-U waves may include hypochloremic alkalosis with hypopotassemia and myocardial damage by anticancer drugs such as daunomycin and aclarubicin chloride used for the underlying disease.