Klinik für Kardiologie und Rhythmologie, Evangelisches Krankenhaus Hagen-Haspe, Brusebrinkstraße 20, 58135, Hagen, Germany.
Department of Cardiology and Electrophysiology, Diakonie Klinikum Siegen, Siegen, Germany.
Herzschrittmacherther Elektrophysiol. 2021 Dec;32(4):467-470. doi: 10.1007/s00399-021-00812-0. Epub 2021 Oct 20.
Amiodarone is commonly used for the treatment of supraventricular and ventricular arrhythmias. As a class III antiarrhythmic drug, it prolongs phase III of the cardiac action potential leading to QT interval prolongation. Therefore, the QTc interval should be monitored during amiodarone up-titration to prevent proarrhythmia. However, QTc monitoring in bundle branch block requires some modification as outlined in this case report. The normal upper value of QT interval has been set at 450 ms for males and 460 ms for females. Patients with preexisting bundle branch block (BBB) by definition exhibit wider QRS intervals, ranging between 120 and 200 ms. This 'augmented' QT interval duration is mainly driven by the prolonged time of ventricular depolarization, rather than the time of ventricular repolarization. This inherent QT interval prolongation in BBB can be corrected with specifically designed electrocardiographic formulas. Nevertheless, accurate QT interval calculation at very low or high heart rates remains challenging.
胺碘酮常用于治疗室上性和室性心律失常。作为一种Ⅲ类抗心律失常药物，它延长了心脏动作电位的相 3，导致 QT 间期延长。因此，在胺碘酮加量期间应监测 QTc 间隔，以防止致心律失常。然而，束支传导阻滞（BBB）中的 QTc 监测需要一些修改，本病例报告对此进行了概述。正常 QT 间期上限值男性设定为 450ms，女性设定为 460ms。根据定义，患有预先存在的束支传导阻滞（BBB）的患者表现出更宽的 QRS 间隔，范围在 120 至 200ms 之间。这种“增强”的 QT 间期持续时间主要是由心室去极化时间延长引起的，而不是心室复极时间延长引起的。BBB 中固有的 QT 间期延长可以用专门设计的心电图公式进行校正。然而，在非常低或高心率下准确计算 QT 间隔仍然具有挑战性。
