Irregular beat-to-beat variations in the shape and amplitude of the ST-T wave during a positive diagnostic ajmaline test

The figure demonstrates visible irregular beat-to-beat variations in the shape and amplitude of the ST-T wave during a positive diagnostic ajmaline test in a 58-year-old female patient with no previous history of arrhythmic events. Only leads V1 and V2 recorded from their standard positions, from the 3rd intercostal space (leads V13 and V23, respectively), and 2nd intercostal space (V12 and V22) are presented (12.5 mm/second, 1 cm/mV). Note the irregular pattern of ST-T wave variability.