Chest Mapping in the Evaluation of Pseudoischemic T Waves Related to Intermittent Left Bundle Branch Block

T-wave changes can be observed in many clinical situations and they are classically divided into primary and secondary T-wave changes. Secondary T- wave changes occur during anomalous ventricular activation while primary changes occur when the activation sequence is normal, thus appearing independent from the pattern of ventricular activation. However, at the resumption of normal intraventricular conduction, after a certain period of anomalous activation, a peculiar type of T-wave changes occurs, which mimics ischemic-type modifications. Such a change needs some time to appear and to reach the maximum level, till anomalous activation is present, and a longer time to disappear, after the disappearance of the abnormal ORS pattern. This phenomenon is suggestive of modulation of repolarization related to the entity and duration of the anomalous activation (1–3).