Momentary giant T-waves hint the genesis of the electrocardiographic T-wave in human.

T-wave morphology changes are linked to dispersion of ventricular repolarization. I encountered an 80-year-old man on hemodialysis manifesting momentary giant T-waves and QT prolongation on the 12-lead electrocardiogram, soon after initiating mechanical ventilation because of hypercapnic respiratory failure. A computed tomography of the brain showed no acute cerebrovascular accidents. An echocardiogram showed no left ventricular asynergy. Mechanisms that may be responsible for this phenomenon are discussed. Interpreting the giant T-waves with the concept of the three bipolar limb lead vectors, the Einthoven's triangle leads to recognize origin of the electrocardiographic T-wave.