Landiolol hydrochloride, also known as Onoact50, is an ultra-short-acting highly selective β1 receptor antagonist. Its primary function is to antagonize β1 receptors present in the heart, thereby improving tachyarrhythmias caused by catecholamine-induced increased heart rate. It is first launched in September 2002. In clinical practice, it is primarily used for the emergency treatment of tachyarrhythmias during surgery (including atrial fibrillation, atrial flutter, and sinus tachycardia) and for the emergency treatment of tachyarrhythmias (including atrial flutter, atrial fibrillation, and sinus tachycardia) under postoperative hemodynamic monitoring.