Three potential mechanisms for failure of high intensity focused ultrasound ablation in cardiac tissue.
Three potential mechanisms for failure of high intensity focused ultrasound ablation in cardiac tissue.
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DOI：
10.1161/circep.111.967216
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发表时间：
2012-04
期刊：
影响因子：
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通讯作者：
Efimov IR
中科院分区：
文献类型：
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作者：
Laughner JI;Sulkin MS;Wu Z;Deng CX;Efimov IR
高强度聚焦超声 (HIFU) 已被引入用于治疗心律失常，因为它能够在有限的体积内快速改变组织，而无需直接接触心肌。尽管 HIFU 有诸多好处，但据报道存在一些局限性，阻碍了其临床应用。在这项研究中，我们使用多模态方法来评估 HIFU 在心脏消融中的热效应和非热效应。我们设计了一个计算机控制系统，能够同时进行荧光映射和 HIFU 消融。使用该系统，通过应用临床剂量（4-16W）的 HIFU，在离体兔心房（n = 6）中产生线性损伤，并在全心（n = 6）制剂的心室中产生点损伤。此外，我们评估了心房准备中传导所需的消融线间隙大小（n = 4）。电压敏感染料 di-4-ANEPPS 用于评估 HIFU 产生的功能损伤。使用光学相干断层扫描和一般组织学来评估病变程度。使用单根消融线在 6 例心房制备中的 1 例（17%）实现了传导阻滞。休息 10 分钟后，6 个心房制剂中有 0 个 (0%) 表现出单根消融线的持续传导阻滞。在 HIFU 应用期间，由于沿病灶线的声辐射力，观察到组织位移 1-3mm。此外，HIFU 产生的过高声压和高温会产生空化，导致宏观组织损伤。发现最小间隙尺寸为 1.5 毫米即可进行电活动。这项研究确定了导致心脏组织 HIFU 消融失败的三种潜在机制。声辐射力和声空化与不一致的热沉积相结合会增加病变不连续性的风险，并导致间隙尺寸增大，从而促进消融失败。
High Intensity Focused Ultrasound (HIFU) has been introduced for treatment of cardiac arrhythmias, because it offers the ability to create rapid tissue modification in confined volumes without directly contacting the myocardium. In spite of the benefits of HIFU, a number of limitations have been reported, which hindered its clinical adoption. In this study, we used a multimodal approach to evaluate thermal and non-thermal effects of HIFU in cardiac ablation. We designed a computer-controlled system capable of simultaneous fluorescence mapping and HIFU ablation. Using this system, linear lesions were created in isolated rabbit atria (n = 6) and point lesions were created in the ventricles of whole-heart (n = 6) preparations by applying HIFU at clinical doses (4–16W). Additionally, we evaluate the gap size in ablation lines necessary for conduction in atrial preparations (n = 4). The voltage sensitive dye di-4-ANEPPS was used to assess functional damage produced by HIFU. Optical coherence tomography and general histology were used to evaluate lesion extent. Conduction block was achieved in 1 (17%) of 6 atrial preparations with a single ablation line. Following 10 minutes of rest, 0 (0%) of 6 atrial preparations demonstrated sustained conduction block from a single ablation line. Tissue displacement of 1–3mm was observed during HIFU application due to acoustic radiation force along the lesion line. Additionally, excessive acoustic pressure and high temperature from HIFU generated cavitation causing macroscopic tissue damage. A minimum gap size of 1.5mm was found to conduct electrical activity. This study identified three potential mechanisms responsible for the failure of HIFU ablation in cardiac tissues. Both acoustic radiation force and acoustic cavitation in conjunction with inconsistent thermal deposition can increase the risk of lesion discontinuity and result in gap sizes that promote ablation failure.