Division of Cardiology, Gunma Prefectural Cardiovascular Center, Maebashi, Gunma, Japan.
Int J Cardiol. 2011 Apr 1;148(1):30-5. doi: 10.1016/j.ijcard.2009.10.018. Epub 2009 Nov 8.
Radiofrequency (RF) ablation produces thermal necrosis and electrophysiological conduction block when lesions are transmural. However, the phenomenon of endocardial edema may prevent the ablative energy from reaching the deeper layers of the myocardium.
Sixty-seven patients underwent RF ablation of the cavotricuspid isthmus (CTI) for isthmus-dependent atrial flutter (AFL; 54 males, 61±9 years). Cardiac magnetic resonance (CMR) imaging was performed 1 day before ablation, and the length and morphology of the CTI were determined. In addition, 1 day and 1 month after ablation, the change in the wall thickness, prevalence of a high signal in the delayed enhancement (DE) and T2-weighted images at the CTI were evaluated.
Before ablation, DE regions at the CTI were found in 2 patients with a concave type and 1 with a pouch type. No region with a high T2 signal at the CTI was observed in any of the 67 patients. One day after ablation, high T2 signals were detected at the CTI, and the wall thickness was significantly augmented (p<0.0001). CMR also revealed a DE at the CTI in 46 patients (69%). One month after ablation, the thickened wall with a high T2 signal recovered to baseline, and a DE at the CTI was found in 56 patients (84%).
CMR is useful for assessing the creation of endocardial edema and scar tissue resulting from CTI ablation. These results may correlate with the anatomical isthmus block after ablation in a large portion of the patients with isthmus-dependent AFL.
射频（RF）消融在病变贯穿时会产生热坏死和电生理传导阻滞。然而，心内膜水肿的现象可能会阻止消融能量到达心肌的更深层。
67 例患者因峡部依赖型房扑（AFL；54 例男性，61±9 岁）接受了 RF 消融治疗。在消融前 1 天进行心脏磁共振（CMR）成像，并确定峡部的长度和形态。此外，在消融后 1 天和 1 个月，评估 CTI 壁厚度的变化、DE 高信号的发生率以及延迟强化（DE）和 T2 加权图像在 CTI 的高信号。
在消融前，2 例患者存在凹型和 1 例患者存在囊袋型的 CTI DE 区域。在 67 例患者中，没有任何患者存在 CTI 处的高 T2 信号。消融后 1 天，CTI 处检测到高 T2 信号，壁厚度明显增加（p<0.0001）。CMR 还在 46 例患者（69%）中发现 CTI 的 DE。消融后 1 个月，增厚的具有高 T2 信号的壁恢复至基线，并且在 56 例患者（84%）中发现 CTI 的 DE。
CMR 可用于评估 CTI 消融引起的心内膜水肿和疤痕组织的形成。这些结果可能与峡部依赖型 AFL 患者中大部分患者的峡部解剖学阻断后相关。
