Ioannidis Panagiotis, Christoforatou Evangelia, Zografos Theodoros, Charalambopoulos Panagiotis, Kouvelas Konstantinos, Christoulas Georgios, Syros Periklis, Tsitsinakis Georgios, Kappou Theodora, Tsoumeleas Andreas, Floros Sotirios, Tagoulis Dimitrios, Ntarladimas Ioannis, Tagoulis Ioannis, Avzotis Dimitrios, Manolis Antonis S, Vassilopoulos Charalambos
Heart Rhythm Center Athens Bioclinic Athens Greece.
First Cardiology Department Red Cross Hospital Athens Greece.
J Arrhythm. 2021 May 12;37(3):584-596. doi: 10.1002/joa3.12545. eCollection 2021 Jun.
After mitral isthmus (ΜΙ) catheter ablation, perimitral atrial flutter (PMF) circuits can be maintained due to the preservation of residual myocardial connections, even if conventional pacing criteria for complete MI block are apparently met (MI pseudo-block). We aimed to study the incidence, the electrophysiological characteristics, and the long-term outcome of these patients.
Seventy-two consecutive patients (mean age 62.4 ± 10.2, 62.5% male) underwent MI ablation, either as part of an atrial fibrillation (AF) ablation strategy (n = 35), or to treat clinical reentrant atrial tachycardia (AT) (n = 32), or to treat AT that occurred during ablation for AF (n = 5). Ιn all patients, the electrophysiological characteristics of PMF circuits were studied by high-density mapping.
Mitral isthmus block was successfully achieved in 69/72 patients (95.6%). Five patients developed PMF after confirming MI block. In these patients, high-density mapping during the PMF showed a breakthrough in MI with extremely low impulse conduction velocity (CV). In contrast, in usual PMF circuits that occurred after AF ablation, the lowest CV of the reentrant circuit was of significantly higher value (0.07 ± 0.02 m/s vs 0.25 ± 0.07 m/s, respectively; < .001). Patients presented with clinical AT had better prognosis in maintaining sinus rhythm after MI ablation compared with patients presented with AF.
Perimitral atrial flutter with MI pseudo-block may be present after MI ablation and has specific electrophysiological features characterized by remarkably slow CV in the MI. Thus, even after MI block is achieved, a more detailed mapping in the boundaries of the ablation line or reinduction attempts may be needed to exclude residual conduction.
二尖瓣峡部（MI）导管消融术后，即使常规起搏标准显示达到完全MI阻滞，但由于残留心肌连接的保留，仍可维持二尖瓣周围房扑（PMF）环路（MI假性阻滞）。我们旨在研究这些患者的发生率、电生理特征及长期预后。
连续72例患者（平均年龄62.4±10.2岁，男性占62.5%）接受MI消融，其中35例作为房颤（AF）消融策略的一部分，32例用于治疗临床折返性房性心动过速（AT），5例用于治疗AF消融过程中发生的AT。所有患者均通过高密度标测研究PMF环路的电生理特征。
72例患者中有69例（95.6%）成功实现二尖瓣峡部阻滞。5例患者在确认MI阻滞后发生PMF。在这些患者中，PMF发作期间的高密度标测显示MI处有突破，冲动传导速度（CV）极低。相比之下，AF消融后出现的常见PMF环路中，折返环路的最低CV值明显更高（分别为0.07±0.02m/s和0.25±0.07m/s；P<0.001）。与AF患者相比，临床诊断为AT的患者在MI消融后维持窦性心律的预后更好。
MI消融术后可能存在伴有MI假性阻滞的二尖瓣周围房扑，其具有特定的电生理特征，表现为MI处CV显著缓慢。因此，即使实现了MI阻滞，仍可能需要在消融线边界进行更详细的标测或再次诱发尝试，以排除残留传导。
