Ashley S, Brooks S G, Gehani A A, Kester R C, Rees M R
Cardiac Research Unit, Killingbeck Hospital, Leeds, UK.
Lasers Surg Med. 1990;10(3):234-44. doi: 10.1002/lsm.1900100304.
Contact probes made from synthetic sapphire crystal, designed for general laser surgery, are currently being evaluated for use in laser angioplasty. Their mode of action and safety in the context of arterial recanalisation is unknown, particularly with respect to the degree of probe and catheter heating. Infrared thermal imaging was used to investigate the surface temperature rise of various rounded sapphire probes during emission of continuous wave Nd-YAG (1,064 nm) laser energy. Catheter safety was addressed by analyzing the temperature of the metal interface between the optical fiber and sapphire, as well as the catheter proximal to this junction. Transmission of Nd-YAG energy through each probe was also measured. Five rounded probes of 1.8-3.0 mm diameter (three supplied by Surgical Laser Technologies [SLT], two by Living Technology [LT]), along with their respective optical catheters, were compared. There was a large temperature gradient between the front and rim of the probes. The maximum surface temperature rise of the sapphire (at 20 W, 5-second exposure) was 314-339 degrees C (SLT) and 90-108 degrees C (LT) [P less than 0.001, 3-way ANOVA]. The reason for this difference may be related to "crazing" of the front surface of the SLT sapphires. At all energy levels sapphire temperatures were considerably lower than attained by metal laser thermal angioplasty probes. Forward transmission was slightly higher in the SLT probes (75-85%) than the LT sapphires (54-69%). With fiber perfusion at 2 ml/minute, a minor degree of heating of the metal sapphire holders was recorded (maximum rise 35 degrees C), but heating of the catheter proximal to this was negligible. Therefore, it would appear that the risk of tip detachment or arterial injury due to heating of the connecting metal interface is extremely low. Without perfusion, however, there was a greater degree of interface heating in the LT delivery system suggestive of more laser backscattering by these sapphires compared with the SLT probes [P less than 0.001, one-way ANOVA]. The SLT system is, therefore, potentially safer in this respect. These results suggest that some degree of surface heating of contact probes due to energy absorption within the sapphire does occur, but is localised to the front of the probe. This effect may contribute to the process of arterial recanalisation with this device. However, variation in the thermal and optical properties of sapphires from different sources has been demonstrated. The influence of these properties on plaque ablation, and ultimately the clinical performance of different contact probe systems, requires further investigation.
由合成蓝宝石晶体制成的接触式探头专为一般激光手术设计，目前正在评估其在激光血管成形术中的应用。它们在动脉再通情况下的作用方式和安全性尚不清楚，特别是在探头和导管加热程度方面。使用红外热成像技术研究了各种圆形蓝宝石探头在连续波Nd-YAG（1064纳米）激光能量发射期间的表面温度升高情况。通过分析光纤与蓝宝石之间金属界面的温度以及该连接处近端的导管温度来探讨导管安全性。还测量了Nd-YAG能量通过每个探头的传输情况。比较了五个直径为1.8 - 3.0毫米的圆形探头（三个由外科激光技术公司[SLT]提供，两个由生命技术公司[LT]提供）及其各自的光导管。探头前端和边缘之间存在很大的温度梯度。蓝宝石的最大表面温度升高（在20瓦、5秒曝光时）为314 - 339摄氏度（SLT）和90 - 108摄氏度（LT）[P小于0.001，三因素方差分析]。这种差异的原因可能与SLT蓝宝石前端表面的“裂纹”有关。在所有能量水平下，蓝宝石温度都远低于金属激光热血管成形术探头所达到的温度。SLT探头的向前传输率（75 - 85%）略高于LT蓝宝石（54 - 69%）。当光纤灌注速度为每分钟2毫升时，记录到金属蓝宝石固定器有轻微程度的加热（最大升高35摄氏度），但近端导管的加热可忽略不计。因此，由于连接金属界面加热导致尖端分离或动脉损伤的风险似乎极低。然而，在无灌注情况下，LT输送系统中界面加热程度更大，这表明与SLT探头相比，这些蓝宝石的激光反向散射更多[P小于0.001，单因素方差分析]。因此，在这方面SLT系统可能更安全。这些结果表明，由于蓝宝石内部能量吸收确实会导致接触式探头表面有一定程度的加热，但局限于探头前端。这种效应可能有助于该装置进行动脉再通的过程。然而，已证明不同来源蓝宝石的热学和光学特性存在差异。这些特性对斑块消融的影响以及最终对不同接触式探头系统临床性能的影响，需要进一步研究。
