A 51‐year‐old woman presented with recurring palpitations. Electrocardiography revealed narrow QRS tachycardia with short RP configuration. Computed tomography showed coronary sinus (CS) ostial atresia along with a small persistent left superior vena cava (PLSVC). Electrophysiological study identified the retrograde earliest atrial activation site (EAAS) at the CS ostium without decremental properties, and para‐Hisian pacing suggested retrograde atrioventricular nodal conduction. Using a 1.6‐Fr microelectrode catheter distally placed in the CS via the PLSVC, EAAS was confirmed within the left atrium, not the CS ostium. Transseptal approach revealed a left lateral accessory pathway, which was successfully eliminated.

中文翻译：

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微电极导管阐明左心房电位：冠状窦口闭锁伴小持续性左上腔静脉一例

一名 51 岁女性因反复心悸就诊。心电图显示窄 QRS 心动过速且 RP 构型短。计算机断层扫描显示冠状窦 (CS) 口闭锁以及小的持续性左上腔静脉 (PLSVC)。电生理学研究确定了 CS 口处的逆行最早心房激动位点 (EAAS)，没有递减特性，旁希斯起搏提示逆行房室结传导。使用通过 PLSVC 远端放置在 CS 中的 1.6-Fr 微电极导管，确认 EAAS 位于左心房内，而不是 CS 口。房间隔入路显露左侧旁路，已成功消除。