Department of Cardiology, Keio University School of Medicine, Tokyo, Japan.
Circ Arrhythm Electrophysiol. 2013 Oct;6(5):1025-31. doi: 10.1161/CIRCEP.113.000810. Epub 2013 Aug 31.
Radiofrequency ablation has limitations, largely related to creation of lesions by heating. Here, we report the first nonthermal ablation by applying photodynamic therapy (PDT) to cardiac tissues using a custom-made deflectable laser catheter. The present study investigated the feasibility of PDT for cavotricuspid isthmus ablation in a canine model.
We evaluated the pharmacokinetic profiles of 17 canines after administration of a photosensitizer (talaporfin sodium) by various protocols. We succeeded in maintaining the photosensitizer concentration at a level in excess of the clinically effective dose for humans. Using a 4-polar 7-French deflectable laser catheter, we performed PDT-mediated cavotricuspid isthmus ablation in 8 canines. PDT caused oxidative injury only to the irradiated area and successfully produced a persistent electric conduction block. No acute, gross changes such as edematous degeneration, thrombus formation, steam pops, or traumatic injury were observed after irradiation. Hematoxylin and eosin staining of tissues samples also showed well-preserved endothelial layers. Testing of the blood samples taken before and after the procedure revealed no remarkable changes. Lesion size at 2 weeks after the procedure and the temperature data collected during irradiation were compared between the PDT and irrigated radiofrequency ablation procedures. A ventricular cross-section revealed a solid PDT lesion, which was as deep as a radiofrequency lesion. In addition, endocardial, surficial, and intramural temperature monitoring during the PDT irradiation clearly demonstrated the nonthermal nature of the ablation technique.
Nonthermal PDT-mediated catheter ablation is a potentially novel treatment for cardiac arrhythmias.
射频消融存在局限性，主要与加热导致的病灶形成有关。在此，我们报告了首例通过应用光动力疗法（PDT）使用定制的可弯曲激光导管对心脏组织进行的非热消融。本研究旨在探讨 PDT 用于犬心房间隔峡部消融的可行性。
我们通过不同方案评估了 17 只犬给药后药物的药代动力学特征。我们成功地将光敏剂（替拉扎明钠）的浓度维持在超过人体临床有效剂量的水平。使用 4 极 7Fr 可弯曲激光导管，我们对 8 只犬进行了 PDT 介导的心房间隔峡部消融。PDT 仅对照射区域造成氧化损伤，并成功产生持续的电传导阻滞。照射后未见急性、大体改变，如水肿变性、血栓形成、蒸汽爆裂或创伤性损伤。组织样本的苏木精和伊红染色也显示出保存完好的内皮层。在程序前后采集的血液样本检测也未发现明显变化。程序 2 周后进行的病变大小和照射过程中收集的温度数据与 PDT 和灌流射频消融程序进行了比较。心室横截面显示出与射频消融一样深的 PDT 病灶。此外，在 PDT 照射过程中进行的心内膜、表面和壁内温度监测清楚地表明了消融技术的非热特性。
非热 PDT 介导的导管消融可能是一种治疗心律失常的新方法。
