The general, electro-physiologic concept of cardiac preexcitation consists of the presence of an accessory electrical path able to activate a portion of the ventricular muscle or the conducting system, earlier than normal. Cardiac preexcitation refers to 2 conducting fronts in equilibrium with each other, with an activation fusion well evident on surface electrocardiogram (ECG) (Fig. 1). Depending on anatomic and physiologic conditions, the preexcitation can be maximal or concealed (Fig. 2). Independently from the degree of preexcitation, an accessory pathway (AP) can be involved in cardiac arrhythmias, which should be carefully identified and investigated and, for this aim, the ECG still represents the best tool. In the past 3 decades, the knowledge of AP has improved after the initial introduction of intracavi-tary EP and later ablation; by this tool the complete the AP anatomy and electrophysiology were confirmed and fully characterized. Manifestations of preexcitation on the ECG have been typically associated with the presence of 3 different features historically named with the first observer (Fig. 3).
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机译：心脏预激的一般电生理学概念包括存在能够比正常更早激活心室肌或传导系统的辅助电路。心脏预激是指 2 个相互平衡的传导前沿，在表面心电图 （ECG） 上非常明显地激活融合（图 1）。根据解剖学和生理条件，预激发可以是最大的，也可以是隐蔽的（图2）。与预兴奋程度无关，心律失常可能涉及辅助通路 （AP），应仔细识别和研究，为此，心电图仍然是最佳工具。在过去的 3 年中，在最初引入椎内 EP 和后来的消融术后，对 AP 的认识有所提高;通过该工具，完整的 AP 解剖学和电生理学得到确认和充分表征。心电图上的预激表现通常与历史上以第一位观察者命名的 3 个不同特征的存在有关（图 3）。
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