Wide QRS-complex tachycardia – elucidating mechanism by atrial pacing maneuvers.
A 44-year-old man with a structurally normal heart presented with a history of regular palpitations. He was not on any medication and his baseline electrocardiogram (ECG) was normal. During the electrophysiologic study, diagnostic catheters were placed in coronary sinus (CS), His bundle – right bundle (HB-RB) region and right ventricular apex (RVA). The His-ventricular (HV) interval was normal (45ms) and CS pacing displayed continuous decremental atrio-ventricular (AV) conduction with no change in the HV interval.