Background and Aims Left atrial appendage electrical isolation (LAAEI) has demonstrated a significant enhancement in the success rate of atrial fibrillation (AF) ablation. Nevertheless, concerns persist about the safety of LAAEI, particularly regarding alterations in left atrial appendage (LAA) flow velocity and the potential risks of thrombus. This study aimed to assess the efficacy and safety of LAAEI, investigating changes in LAA flow velocity in canines. Methods The study comprised a total of ten canines. The LAAEI procedure used by a 23mm cryoballoon (CB) of the second generation was conducted at least 180 seconds. Intracardiac ultrasonography (ICE) was employed to quantify the velocity flow of the LAA both prior to and following LAAEI. Following a three-month period, subsequent evaluations were performed to assess the LAA velocity flow and the potential reconnection. Histopathological examination was conducted. Results LAAEI was effectively accomplished in all canines, resulting in a 100% acute success rate (10/10). The flow velocity in the LAA showed a notable reduction during LAAEI as compared to the values before the ablation procedure (53.12±5.89 cm/s vs 42.01±9.22 cm/s, P= 0.007). After the follow-up, reconnection was observed in four canines, leading to a success rate of LAAEI of 60% (6/10). The flow velocity in the LAA was consistently lower (53.12±5.89 cm/s vs 44.33±10.49 cm/s, P = 0.006), and no blood clot development was observed. The histopathological study indicated that there was consistent and complete injury to the LAA, affecting all layers of its wall. The injured tissue was subsequently replaced by fibrous tissue. Conclusion The feasibility of using cryoballoon ablation for LAAEI was confirmed in canines, leading to a significant reduction of LAA flow velocity after ablation. Some restoration of LAA flow velocity after ablation may be linked to the passive movement of the LAA and potential reconnecting. However, this conclusion is limited to animal study, more clinical data are needed to further illustrate the safety and accessiblity of LAAEI in humans.

中文翻译：

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第二代冷冻球囊用于犬左心耳电隔离的安全性和有效性

背景和目的左心耳电隔离（LAAEI）已证明可以显着提高心房颤动（AF）消融的成功率。然而，人们对 LAAEI 的安全性仍然存在担忧，特别是左心耳 (LAA) 流速的改变和血栓的潜在风险。本研究旨在评估 LAAEI 的有效性和安全性，研究犬类 LAA 流速的变化。方法 该研究共有十只犬科动物。第二代 23mm 冷冻球囊 (CB) 使用的 LAAEI 程序至少进行了 180 秒。采用心内超声检查 (ICE) 来量化 LAAEI 之前和之后 LAA 的速度流量。三个月后，进行了后续评估，以评估左心耳速度流和潜在的重新连接。进行组织病理学检查。结果 LAAEI 在所有犬科动物中均有效完成，急性成功率达 100% (10/10)。与消融手术前相比，LAAEI 期间左心耳的流速显着降低（53.12±5.89 cm/s vs 42.01±9.22 cm/s，P= 0.007）。随访后，在四只犬中观察到重新连接，LAAEI 的成功率为 60%（6/10）。 LAA 中的流速始终较低（53.12±5.89 cm/s vs 44.33±10.49 cm/s，P = 0.006），并且未观察到血栓形成。组织病理学研究表明左心耳存在一致且完全的损伤，影响其壁的所有层。受伤的组织随后被纤维组织取代。结论 在犬科动物中证实了冷冻球囊消融治疗 LAAEI 的可行性，导致消融后 LAA 流速显着降低。消融后左心耳流速的一些恢复可能与左心耳的被动运动和潜在的重新连接有关。但这一结论仅限于动物研究，还需要更多的临床数据来进一步说明LAAEI在人体中的安全性和可及性。