差异性起搏法对典型心房扑动消融后峡部完全传导阻滞的预测价值

The value of differential pacing in predicting isthmus conduction block after ablation of typical atrial flutter

目的探讨一种简单的方法用以鉴别峡部消融线是完全阻滞还是存在缓慢传导,以降低典型心房扑动(简称房扑)消融后的复发率。方法前瞻性研究30例典型房扑患者消融后峡部的传导,放置20极Halo电极,使最远端的两对电极靠近阻滞线,分别起搏这两对电极并在消融线上标测局部双电位或多电位,我们假设局部电位的初始成分和终末成分分别代表消融线两侧的激动,当起搏部位由离消融线较近的电极对转为较远电极对起搏时,刺激信号到局部电位初始电位成分的时间将会延迟,而刺激信号到局部电位终末成分的时间变化取决于阻滞线是否完整。终末电位提前或不变提示完全阻滞,终末电位延迟提示阻滞线上有传导缝隙。结果用传统判断峡部阻滞的方法做参照标准,选取位点进行差异性起搏共54次,峡部完全阻滞前18次,峡部完全阻滞后36次。当起搏部位转为较远电极对时,初始电位均延迟,平均18±9ms,峡部不全阻滞时,终末电位延迟13±7ms,峡部完全阻滞后,终末电位提前12±8ms。差异性起搏对预测峡部完全阻滞的灵敏度达100%,特异度达88.9%。结论差异性起搏可准确鉴别峡部形成完全阻滞还是存在缓慢传导。

Objective Complete conduction block of cavotricuspid isthmus is necessary to minimize the recurrence of typical atrial flutter, we investigated a simple technique to distinguishing block from persistent conduction through an isthmus ablation line. Methods We prospectively evaluated isthmus conduction in 30 patients after radiofrequency ablation. Halo catheter was placed with the most distal two pairs of bipoles close to the ablation line , the two pairs of bipoles were successively stimulated during recording double or multiple potentials from the ablation line. We hypothesized that because the initial and terminal components of local potentials reflected activation at the ipsilateral and contralateral borders of the ablation lesion, a change to a more proximal pacing site would prolong the stimulus to the initial component timing, whereas the response of the terminal component would depend on the presence of block or persistent conduction. A shortening or no change in timing of the terminal component would indicate block, whereas lengthening would indicate persistent gap conduction. Results The results were compared with traditional criteria for isthmus block. 54 sites were assessed ： 18 before and 36 after the achievement of complete isthmus block. The timing of the initial component was delayed by 18 ± 9 ms , and the terminal component was delayed by 13 ± 7ms in case of persisting conduction and advanced by 12 ± 8 ms after block. The sensitivity and specificity of differential pacing in predicting isthmus conduction were 100% and 88.9% respectively. Conclusions An accurate assessment of isthmus block or persistent isthmus conduction is possible with this technique of differential pacing.