Hazama Hisanao, Yoshimori Masato, Honda Norihiro, Awazu Kunio
Graduate School of Engineering, Osaka University.
Institute for Academic Initiatives, Osaka University.
Laser Ther. 2017 Dec 31;26(4):282-287. doi: 10.5978/islsm.17-RE-03.
Endovenous laser ablation (EVLA) has been well-reported as a minimally invasive method to deal with varices of the lower extremities. The lasers used fall into two categories: pigment, i.e., hemoglobin-specific lasers in the visible and near-infrared (near-IR) wavebands and longer wavelength mid-infrared lasers where the chromophore is water. The fiber used to deliver the laser energy is also important, and not enough attention has been paid to this element of EVLA. The present study was therefore designed to compare EVLA delivered through two specific fiber types coupled with a near-IR laser wavelength where water was the major chromophore.
A laser diode system at the wavelength of 1470 nm was used as the laser energy source near a peak in the water absorption spectrum. Laser energy was delivered with two specific types of optical fiber, a Radial™ fiber and a Radial 2ring™ fiber (CeramOptec, Germany), and EVLA was evaluated using a computer simulation model taking light transport into account based on the Monte Carlo method and temperature distribution with the heat conduction equation.
It was confirmed from both the simulation model and a previously published experiment that carbonization and sticking during EVLA caused by excess temperature rise can be minimized by using the Radial 2ring fiber compared with the Radial fiber, coupled with the 1470 nm wavelength. In the future, lasers with different wavelengths or optical fibers with differing irradiation modes may appear as candidate systems for EVLA. It is important to evaluate safety and efficacy carefully using the methods in the present study before moving to indications in human subjects.
静脉腔内激光消融术（EVLA）作为一种治疗下肢静脉曲张的微创方法已有大量报道。所使用的激光分为两类：色素类，即可见光和近红外（近红外）波段中针对血红蛋白的激光，以及发色团为水的较长波长的中红外激光。用于传输激光能量的光纤也很重要，但在EVLA的这一要素方面尚未得到足够重视。因此，本研究旨在比较通过两种特定类型光纤传输的EVLA，并结合以水为主要发色团的近红外激光波长。
使用波长为1470 nm的激光二极管系统作为接近水吸收光谱峰值处的激光能量源。激光能量通过两种特定类型的光纤传输，即Radial™光纤和Radial 2ring™光纤（德国CeramOptec公司），并使用基于蒙特卡罗方法考虑光传输以及利用热传导方程考虑温度分布的计算机模拟模型对EVLA进行评估。
从模拟模型和先前发表的实验均证实，与Radial光纤相比，使用Radial 2ring光纤并结合1470 nm波长，可将EVLA期间因温度过度升高导致的碳化和粘连降至最低。未来，具有不同波长的激光或具有不同照射模式的光纤可能会作为EVLA的候选系统出现。在应用于人体受试者之前，使用本研究中的方法仔细评估安全性和有效性非常重要。
