Temporal sinus node modification by high-dose continuous intravenous administration of landiolol in a patient with persistent inappropriate sinus tachycardia.

A 20-year-old woman underwent an electrophysiological study for drug-resistant persistent inappropriate sinus tachycardia (IST). Use of a high-dose continuous intravenous administration of landiolol, a short-acting beta-adrenoreceptor blocker, made the patient׳s heart rate suddenly drop with a slight change in the P-wave morphology. Three-dimensional right atrial (RA) activation mapping revealed that the earliest activation site moved 8 mm to a lower anterior site around the high lateral RA. Radiofrequency energy applied to the earliest activation site during tachycardia was successful. A temporal sinus node modification with landiolol administration was useful for mapping and for safe catheter ablation of IST.