Division of Cardiovascular Medicine, University of Utah, 30 N 1900 E Rm 4A100, Salt Lake City, UT, USA.
Department of Bioengineering, University of Utah, Salt Lake City, UT, USA.
Europace. 2019 Jan 1;21(1):154-162. doi: 10.1093/europace/euy089.
The goals of this study were to develop a method that combines cryoablation with real-time magnetic resonance imaging (MRI) guidance for pulmonary vein isolation (PVI) and to further quantify the lesion formation by imaging both acute and chronic cryolesions.
Investigational MRI-compatible cryoablation devices were created by modifying cryoballoons and cryocatheters. These devices were used in canines (n = 8) and a complete series of lesions (PVI: n = 5, superior vena cava: n = 4, focal: n = 13) were made under real-time MRI guidance. Late gadolinium enhancement (LGE) magnetic resonance imaging was acquired at acute and chronic time points. Late gadolinium enhancement magnetic resonance imagings show a significant amount of acute tissue injury immediately following cryoablation which subsides over time. In the pulmonary veins, scar covered 100% of the perimeter of the ostium of the veins acutely, which subsided to 95.6 ± 4.3% after 3 months. Focal point lesions showed significantly larger acute enhancement volumes compared to the volumes estimated from gross pathology measurements (0.4392 ± 0.28 cm3 vs. 0.1657 ± 0.08 cm3, P = 0.0043). Additionally, our results with focal point ablations indicate that freeze-zone formation reached a maximum area after 120 s.
This study reports on the development of an MRI-based cryoablation system and shows that with acute cryolesions there is a large area of reversible injury. Real-time MRI provides the ability to visualize the freeze-zone formation during the freeze cycle and for focal lesions reaches a maximum after 120 s suggesting that for maximizing lesion size 120 s might be the lower limit for dosing duration.
本研究旨在开发一种结合冷冻消融与实时磁共振成像（MRI）指导的肺静脉隔离（PVI）方法，并通过影像学手段对急性和慢性冷冻损伤进行定量分析。
通过对冷冻球囊和冷冻导管进行改良，研制出了可用于 MRI 检查的冷冻消融设备。在犬模型（n=8）中，利用这些设备完成了一系列完全的消融实验（PVI：n=5，上腔静脉：n=4，局灶性：n=13），全程均在实时 MRI 引导下进行。在急性和慢性时间点进行对比剂增强磁共振成像（LGE-MRI）检查。LGE-MRI 结果显示，冷冻消融后即刻即刻即发生大量急性组织损伤，随着时间的推移逐渐消退。在肺静脉中，冷冻即刻，静脉口的周长完全被瘢痕覆盖，3 个月后消退至 95.6±4.3%。与大体病理测量结果相比，局灶性病变的急性增强体积明显更大（0.4392±0.28 cm3 vs. 0.1657±0.08 cm3，P=0.0043）。此外，我们的局灶性消融实验结果表明，冷冻区形成在 120 秒后达到最大面积。
本研究报告了一种基于 MRI 的冷冻消融系统的开发，并表明急性冷冻损伤存在较大面积的可逆性损伤。实时 MRI 提供了在冷冻周期中可视化冷冻区形成的能力，对于局灶性病变，在 120 秒后达到最大面积，这表明为了最大限度地增大病变面积，120 秒可能是治疗时间的下限。
