Lilge L, Radtke W, Nishioka N S
Wellman Laboratories of Photomedicine, Massachusetts General Hospital, Boston 02114.
Lasers Surg Med. 1989;9(5):458-64. doi: 10.1002/lsm.1900090506.
Ablation efficiency and residual thermal damage produced by pulsed holmium laser radiation were investigated in vitro for bovine mitral valves and human calcified and noncalcified cardiac valves. Low-OH quartz fibers (200 and 600 microns core diameter) were used in direct contact perpendicular to the specimen under saline or blood. Etch rate was measured with a linear motion transducer. Radiant exposure was varied from 0 to 3 kJ/cm2. For 200-microns fibers, the energy of ablation was approximately 5 kJ/cm3 in noncalcified and 15 kJ/cm3 in calcified valves. Etch rates were dependent on mechanical tissue properties. Maximum etch rate at 1,000 J/cm2 was 1-2 mm/pulse at 3 Hz repetition rate. Microscopic examination revealed a zone of thermal damage extending 300 microns lateral into adjacent tissue. Thermal damage was independent of radiant exposure beyond twice threshold.
在体外研究了脉冲钬激光辐射对牛二尖瓣以及人体钙化和非钙化心脏瓣膜产生的消融效率和残余热损伤。使用低羟基石英光纤（纤芯直径200和600微米），在生理盐水或血液下垂直与样本直接接触。用线性运动传感器测量蚀刻速率。辐射曝光量在0至3 kJ/cm²之间变化。对于200微米的光纤，在非钙化瓣膜中的消融能量约为5 kJ/cm³，在钙化瓣膜中为15 kJ/cm³。蚀刻速率取决于组织的机械性能。在1000 J/cm²时，以3 Hz重复频率的最大蚀刻速率为1 - 2毫米/脉冲。显微镜检查显示，热损伤区域向相邻组织横向延伸300微米。超过两倍阈值后，热损伤与辐射曝光量无关。
