Arai Tomoyuki, Hojo Rintaro, Kitamura Takeshi, Fukamizu Seiji
Department of Cardiology, Tokyo Metropolitan Hiroo Hospital, 2-34-10, Ebisu, Shibuya-ku, Tokyo 150-0013, Japan.
Eur Heart J Case Rep. 2020 Sep 9;4(5):1-4. doi: 10.1093/ehjcr/ytaa312. eCollection 2020 Oct.
Superior vena cava (SVC) isolation has improved the outcomes of paroxysmal atrial fibrillation (AF) originating from the SVC. However, right phrenic nerve (PN) injury is a major complication of this procedure. Therefore, in cases where the right atrium (RA)-SVC conduction site is near the PN, tremendous care is required to prevent PN injury.
Repeated SVC isolation was performed due to the recurrence of SVC-triggered AF. The RA-SVC activation map revealed that the partial conduction block line was detected, and the propagation broke through the gap at the course of the PN site from the RA to the SVC. Since the course of the PN identified at high-output pacing was wide, the SVC was isolated by making longitudinal lines on both sides of the PN in a cranial direction, except for where low-output pacing captured, confirming compound muscle action potential to detect PN injury. Eventually, the SVC was successfully isolated without PN injury, and the sinus rhythm was maintained without antiarrhythmic drugs during a 14-month follow-up period.
Superior vena cava isolation was difficult depending on the course of the PN, and some methods to avoid PN injury were reported. However, this method can facilitate safe and effective SVC isolation with the conventional system, including the cases with AF foci located on the course of the PN.
上腔静脉（SVC）隔离改善了起源于SVC的阵发性心房颤动（AF）的治疗效果。然而，右侧膈神经（PN）损伤是该手术的主要并发症。因此，在右心房（RA）-SVC传导部位靠近PN的情况下，需要格外小心以防止PN损伤。
由于SVC触发的AF复发，进行了重复的SVC隔离。RA-SVC激动标测显示检测到部分传导阻滞线，激动从RA到SVC在PN部位的行程中突破了间隙。由于在高输出起搏时识别出的PN行程较宽，除了低输出起搏夺获的部位外，在PN两侧向头侧方向制作纵向线来隔离SVC，通过确认复合肌肉动作电位来检测PN损伤。最终，成功隔离了SVC且未发生PN损伤，在14个月的随访期内未使用抗心律失常药物维持窦性心律。
上腔静脉隔离因PN的行程而异，且有一些避免PN损伤的方法被报道。然而，该方法可通过传统系统促进安全有效的SVC隔离，包括AF病灶位于PN行程上的病例。
