Strebel R T, Utzinger U, Peltola M, Schneider J, Niederer P F, Hess O M
Department of Internal Medicine, University and Swiss Federal Institute of Technology, University Hospital, Zurich, Switzerland.
J Laser Appl. 1998 Feb;10(1):34-40. doi: 10.2351/1.521831.
Limited steerability and injury to the normal vessel wall are major drawbacks of laser coronary angioplasty. To overcome these limitations a new generation of laser systems has been developed which allows not only to eliminate the atherosclerotic plaque but to guide the laser beam by analyzing the laser induced tissue fluorescence (= spectroscopy) for the treatment of the atherosclerotic vessel. An excimer laser (MAX 10 LP, 308 nm, Technolas, Munich, Germany) was used with an emitting (phi 1070 microns) and a detecting (phi 130 microns) optical fiber to induce tissue fluorescence which was analyzed quantitatively by a computerized system. Specimens from the descending (thoracic) aorta were obtained from 24 patients (mean age 68.1 years, range 44-92). Tissue fluorescence was induced with ablating (26-30 mJ/mm2) and nonablating (3 mJ/cm2) laser activations. The emitted fluorescence (range 380-575 nm) was normalized to a wavelength of 380 nm; as a measure of tissue fluorescence the intensity ratio at 500 nm divided by 400 nm was calculated in normal (n = 78), mildly atherosclerotic (n = 40), and severely atherosclerotic (n = 48) tissue samples. Repeated laser activations were carried out and tissue fluorescence was checked until the fluorescence spectrum was normalized. All tissue samples were analyzed histologically by a semiquantitative score. Normal tissue samples showed the highest intensity ratios (5.9 +/- 3.4), whereas mildly (2.9 +/- 1.3) and severely atherosclerotic (2.1 +/- 1.0) samples elicited a significantly reduced fluorescence. Repeated tissue ablations were associated with a normalization of fluorescence intensity ratios in the mildly (7.0) as well as in the severely diseased (4.9) vessels. A curvilinear relationship between intensity ratio and the semiquantitative score was observed (r = 0.66) as well as between intensity ratio and intimal wall thickness (r = 0.62). No gender related differences were found but there was an inverse relationship between fluorescence intensity ratio and age (r = 0.56) as well as between intimal thickness and age (r = 0.41). Excimer laser spectroscopy allows reliable detection of atherosclerotic vessel alterations. Fluorescence intensity ratio is inversely proportional to the intimal wall thickness and the severity of the histologic alterations. There is an age dependency of fluorescence intensity ratio which can be explained by an increase in intimal wall thickness. Successful tissue ablation can be obtained by laser angioplasty and allows determination of the optimal point where complete tissue ablation is achieved by laser activation. Thus, excimer laser spectroscopy is an effective method for selective tissue ablation by laser angioplasty.
激光冠状动脉成形术的主要缺点是可控性有限以及对正常血管壁造成损伤。为克服这些局限性，已开发出新一代激光系统，该系统不仅能够消除动脉粥样硬化斑块，还能通过分析激光诱导的组织荧光（=光谱学）来引导激光束，用于治疗动脉粥样硬化血管。使用准分子激光（MAX 10 LP，308纳米，德国慕尼黑Technolas公司），通过一根发射光纤（直径1070微米）和一根检测光纤（直径130微米）诱导组织荧光，并由计算机系统进行定量分析。从24例患者（平均年龄68.1岁，范围44 - 92岁）的降主动脉（胸段）获取标本。分别采用消融性（26 - 30毫焦/平方毫米）和非消融性（3毫焦/平方厘米）激光激活诱导组织荧光。发射的荧光（范围380 - 575纳米）以380纳米波长进行归一化处理；作为组织荧光的度量，计算正常组织（n = 78）、轻度动脉粥样硬化组织（n = 40）和重度动脉粥样硬化组织（n = 48）样本在500纳米与400纳米处的强度比。进行多次激光激活并检查组织荧光，直至荧光光谱归一化。所有组织样本均通过半定量评分进行组织学分析。正常组织样本显示出最高的强度比（5.9 ± 3.4），而轻度（2.9 ± 1.3）和重度动脉粥样硬化（2.1 ± 1.0）样本的荧光明显降低。在轻度病变（7.0）以及重度病变（4.9）血管中，重复组织消融与荧光强度比的归一化相关。观察到强度比与半定量评分之间呈曲线关系（r = 0.66），强度比与内膜厚度之间也呈曲线关系（r = 0.62）。未发现性别相关差异，但荧光强度比与年龄之间呈负相关（r = 0.56），内膜厚度与年龄之间也呈负相关（r = 0.41）。准分子激光光谱学能够可靠地检测动脉粥样硬化血管病变。荧光强度比与内膜厚度和组织学改变的严重程度成反比。荧光强度比存在年龄依赖性，这可以通过内膜厚度的增加来解释。通过激光血管成形术可以成功实现组织消融，并能够确定通过激光激活实现完全组织消融的最佳点。因此，准分子激光光谱学是一种通过激光血管成形术进行选择性组织消融的有效方法。
