Department of Anatomy and Cell Biology, Universidad de Extremadura, Badajoz, Spain.
Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
Heart. 2022 Aug 25;108(18):1430-1437. doi: 10.1136/heartjnl-2021-320304.
Knowledge of the anatomy of the 'conduction tissues' of the heart is a 20th century phenomenon. Although controversies still continue on the topic, most could have been avoided had greater attention been paid to the original descriptions. All cardiomyocytes, of course, have the capacity to conduct the cardiac impulse. The tissues specifically described as 'conducting' first generate the cardiac impulse, and then deliver it in such a fashion that the ventricles contract in orderly fashion. The tissues cannot readily be distinguished by gross inspection. Robust definitions for their recognition had been provided by the end of the first decade of the 20th century. These definitions retain their currency. The sinus node lies as a cigar-shaped structure subepicardially within the terminal groove. There is evidence that it is associated with a paranodal area that may have functional significance. Suggestions of dual nodes, however, are without histological confirmation. The atrioventricular node is located within the triangle of Koch, with significant inferior extensions occupying the atrial vestibules and with septal connections. The conduction axis penetrates the insulating plane of the atrioventricular junctions to continue as the ventricular pathways. Remnants of a ring of cardiomyocytes observed during development are also to be found within the atrial vestibules, particularly a prominent retroaortic remnant, although that their role has still to be determined. Application of the initial criteria for nodes and tracts shows that there are no special 'conducting tissues' in the pulmonary venous sleeves that might underscore the abnormal rhythm of atrial fibrillation.
心脏“传导组织”的解剖学知识是 20 世纪的现象。尽管关于这个主题仍然存在争议，但如果更加关注最初的描述，大多数争议本来是可以避免的。当然，所有心肌细胞都有传导心脏冲动的能力。首先产生心脏冲动的组织，然后以这样的方式传递冲动，使心室有序地收缩。这些组织不能通过肉眼检查轻易区分。到 20 世纪第一个十年末，已经为它们的识别提供了强有力的定义。这些定义仍然适用。窦房结呈雪茄形结构，位于终末沟的心外膜下。有证据表明，它与可能具有功能意义的副节段区有关。然而，关于双结的说法，没有组织学证据。房室结位于 Koch 三角内，有明显的下延占据心房前庭，并与间隔相连。传导轴穿透房室结的绝缘平面，继续作为心室途径。在发育过程中观察到的心肌细胞环的残留物也存在于心房前庭内，特别是一个突出的主动脉后残留物，尽管其作用仍有待确定。应用节点和束的初始标准表明，肺静脉套中没有特殊的“传导组织”，这可能强调了心房颤动的异常节律。
