Department of Cardiology, The Jikei University School of Medicine, Tokyo, Japan.
J Cardiovasc Electrophysiol. 2011 Dec;22(12):1331-8. doi: 10.1111/j.1540-8167.2011.02112.x. Epub 2011 Jun 7.
Although mitral isthmus (MI) ablation in atrial fibrillation (AF) patients has been shown to be an effective ablative strategy, the establishment of the bidirectional conduction block of the MI is technically challenging. We investigated the usefulness of a steerable sheath for MI ablation in patients with persistent AF and its impact on the clinical outcome of persistent AF ablation.
A total of 80 consecutive patients undergoing MI ablation were randomized to 1 of the following 2 groups: group S (using a steerable long sheath) or group NS (using a nonsteerable long sheath). MI ablation was performed by using an open-irrigated ablation catheter with the guidance of a 3-dimensional mapping system. The endpoint of the MI ablation was the achievement of a bidirectional block.
Bidirectional block through the MI was achieved in 87.5% (70/80) of patients with 14.0 ± 6.7 minutes of radiofrequency application. The bidirectional block was more frequently achieved in patients in group S compared to group NS (97.5% (39/40) vs 77.5% (31/40), P = 0.02). Additionally, epicardial ablation within the coronary sinus was less frequently required in group S compared to group NS (12.5% (5/40) vs 72.5% (29/40), P < 0.0001). Atrial tachycardia after the procedure more frequently occurred in the patients in whom MI block had not been achieved during the initial procedure (40.0% (4/10) vs 10.0% (7/70), P = 0.04).
The MI block could be achieved in the majority of patients by using a steerable sheath. An incomplete MI block increased the risk of AT following persistent AF ablation.
尽管在心房颤动（AF）患者中进行二尖瓣峡部（MI）消融已被证明是一种有效的消融策略，但 MI 的双向传导阻滞的建立在技术上具有挑战性。我们研究了在持续性 AF 患者中使用可转向鞘管进行 MI 消融的有效性及其对持续性 AF 消融临床结果的影响。
共有 80 例连续接受 MI 消融的患者被随机分为以下 2 组之一：组 S（使用可转向长鞘）或组 NS（使用不可转向长鞘）。MI 消融是在三维标测系统的指导下使用开放灌流消融导管进行的。MI 消融的终点是实现双向阻滞。
80 例患者中有 87.5%（70/80）通过 14.0±6.7 分钟的射频应用实现了 MI 的双向阻滞。与组 NS 相比，组 S 中的患者更频繁地实现了 MI 的双向阻滞（97.5%（39/40）比 77.5%（31/40），P=0.02）。此外，与组 NS 相比，组 S 中需要进行心外膜消融的情况较少（12.5%（5/40）比 72.5%（29/40），P<0.0001）。在初始手术中未能实现 MI 阻滞的患者术后更常发生房性心动过速（40.0%（4/10）比 10.0%（7/70），P=0.04）。
使用可转向鞘管可以使大多数患者实现 MI 阻滞。MI 不完全阻滞增加了持续性 AF 消融后发生房性心动过速的风险。
