COMPARATIVE EXPERIMENTAL STUDY OF HO-YAG LASER AND TRUE- CUT BIOPSY NEEDLE IN MYOCARDIAL REVASCULARIZATION

Objective.To study the mechanism and effects of blood perfusion on acute ischemic region of myocardium through channel created by Ho- Yag laser and True- cut biopsy needles with myocardial contrast echocardiography. Methods. We partially ligated the left anterior descending coronary artery of canine hearts between the lst and 2nd diagonal branches to produce two groups of acute myocardial ischemia models and then performed tran- smyocardial revascularization (TMR) on this region with Ho- Yag laser and True- cut biopsy needles. Myocardial contrast echocardiography was performed with a new generation of ultrasound contrast agent and second harmonic imaging of this region before, during ischemia and after revascularization. Pictures were taken with“ R” wave trigger skill. Results. Acoustic density (dB) in the ischemic region (anterior wall) with myocardial contrast echocardiography decreased obviously after the left anterior descending artery was ligated (Laser group: 5.40± 1.81, Needle group: 7.11± 2.51) compared with that before (Laser group: 11.69± 1.61, Needle group: 12.96± 2.88, P< 0.01). dB increased remarkably after TMR by either laser or True cut biopsy needle (Laser group: 11.02± 2.01, Needle group: 10.01± 4.45. P< 0.01) compared to that during ischemia and approximated to that before ischemia (P >0.05). We found that the acoustic density of the contrast developed one picture (one cardiac cycle) ahead in the transmyocardial revascularization region than that in the lateral and other region of the left ventricle wall in the scan of both groups. Conclusions. Acute ischemic myocardium can be perfused immediately by oxygenated blood from the left ventricle through channels created with both Ho- Yag laser and True- cut biopsy needles. Evidence of blood perfusion through these channels mainly during systolic phase was detected, and myocardial contrast ultrasound using intravenous perfluorocarbon- exposed sonicated dextrose albumin was regarded as a reliable method in the study of transmyocardial revascularization.

Role of Removing Stasis and Reducing Heat Formula in Clearance of Proximal Ureteral Calculi after Ureteroscopic Ho:YAG Laser Lithotripsy: A Prospective Randomized Study

Objective To prospectively evaluate the efficacy of Removing Stasis and Reducing Heat Formula in accelerating calculus clearance and improving lower urinary tract symptoms of patients with proximal ureteral calculi after ureteroscopic Ho:YAG laser lithotripsy. Methods A total of 138 patients with proximal ureteral calculi underwent ureteroscopic Ho:YAG laser lithotripsy by a single endocrinologist. Stone size varied from 10 to 15 mm. After operation, the patients were randomly divided into three groups: the control group(group A), tamsulosin group(group B), and Removing Stasis and Reducing Heat Formula group(group C). The treatment lasted for 4 weeks or until stone clearance. The primary and secondary outcomes of the three groups at follow-up were assessed. Results Of the 131 patients available for follow-up, 44 cases were in the group A, 45 in the group B, and 42 in the group C, respectively. The stone free rate at 2 weeks in the groups B and C were significantly higher than that in the group A(95.56%, 97.62% vs. 79.55%; all P<0.05). The ureteral colic rate and mean time of fragment expulsion were significantly reduced in the groups B(4.44% and 7.86±4.99 days) and C(2.43% and 6.76±4.37 days) compared with the group A(22.73% and 11.54±9.89 days, all P<0.05). On the day of double-J ureteric stent removal, the group C differed significantly from the group A in the total International Prostate Symptom Score, irritative subscore, obstructive subscore, and quality of life score(all P<0.05). Conclusion Removing Stasis and Reducing Heat Formula in the medical expulsive therapy might be an effective modality for patients with calculus in the proximal uretera after ureteroscopic Ho:YAG laser lithotripsy.

A Stable Wavelength Operation Ho:YAG Laser with Orthogonally Polarized Pump

A stable wavelength operation Ho:YAG laser dual-pumped by two orthogonally polarized Tm:YLF lasers is reported. Under the cw operation mode, a laser output power of 24 W is measured. The corresponding opticaloptical conversion efficiency is 44.75% and the slope efficiency is 50.12%. Under the Q-switched operation mode,the output maximum average power is 22.8 W at the re-frequency of 6 kHz. The corresponding optical-optical conversion efficiency and slope efficiency are 42.64% and 48.01%, respectively. The output central wavelength is 2090.73 nm, the linewidth is 0.40 nm, and the beam quality is M^2< 1.6. Moreover, the shift of the output central wavelength is less than 0.01 nm, and the linewidth shift is also less than 0.01 nm.

An Actively Mode-Locked Ho:YAG Solid-Laser Pumped by a Tm-Doped Fiber Laser

An actively mode-locked Ho： YAG laser pumped by a diode-pumped Tin-doped fiber laser is reported. For the cw operation, we obtain the maximum output power of 3.43 W with a central wavelength 2022.2nm at the maximum incident pump power of 11.4 W, corresponding to a slope efficiency of 34.5%. The beam quality factor M2 is 1.16, and the output beam is close to fundamental TEMoo. In the case of the CWML operation, a stable pulse train is generated with an average output power up to 3.41 W with a slope efficiency of 34.3% at the incident pump power of 11.4 W and a pulse duration of 294ps at a repetition rate of 81.92MHz. In addition, the maximum single pulse energy is 41.6nJ.

Combined Use of Transmyocardial Laser Revascularization and Endothelial Progenitor Cells Enhances Neovascularization and Regional Contractility in a Canine Model of Ischemic Hearts

The purpose of this study was to determine the combined effect of transmyocardial laser re- vascularization （TMLR） and the implantation of endothelial progenitor cells （EPCs） on cardiac function of ischemic hearts in canines. The left anterior descending artery （LAD） was occluded to establish the canine model of acute myocardial infarct （AMI）. Four weeks later, the animals were randomly divided into four groups： TMLR group, in which transmyocardial laser-induced channels were established at the ischemic region; EPCs＋TMLR group, in which EPCs were locally transplanted into laser-induced chan- nels at the ischemic region; EPCs group, in which the EPCs were injected into the ischemic region; con- trol group, in which the AMI animals received neither TMLR nor EPCs. The peripheral blood （50 mL） was sampled in all groups. Mononuclear cells from the peripheral blood were separated and cultured to obtain spindle-shaped attaching （AT） cells in vitro. AT cells were labeled with 1, 1 ＇-dioctadecyl-1 to 3,3, 3＇,3＇-tetramethyl-indocarbocyanine perchlorate （DiI） before injecting into the laser-induced channels or ischemic region. Four weeks after the first operation, TMLR was performed in the TMLR group and EPCs＋TMLR group, and at the same time, the EPCs originating from the AT cells were mixed with cal- cium alginate （CA）. Then the EPCs-CA composites were implanted into myocardial channels induced by laser in the EPCs＋TMLR group, and into the myocardial infarct area in the EPCs group. All dogs underwent echocardiography at second month after LAD occlusion. Finally the samples of myocardium around the LAD were subjected to histochemical and immunohistologic examinations. The results showed there was no significant difference in the diameter of left atrium and ventricle before treatment among all groups （P〉0.05）. Eight weeks after modeling, the regional contractility in the LAD territory in the EPCs＋TMLR group was increased as compared with control group and TMLR group, but there was no significant difference between control group and TMLR group. Neoangiogenesis was observed in the EPCs＋TMLR group, and the fibrosis was seen in the TMLR group. There was no significant dif- ference in neoangiogenesis around the channels induced by laser among EPCs＋TMLR, EPCs and TMLR groups. It was concluded that TMLR combined with EPCs could improve the regional and global cardiac function in AMI, and augment neovascularizaiton in channels of ischemic myocardium induced by laser.

Development of a Single-Longitudinal-Mode Ho:YAG Laser Based on Corner Cube

We present a Tm-doped fiber laser pumped Fabry-Perot etalons Ho：YAG laser based on a corner cube. A maximum single-longitudinal-mode and fundamental transverse mode output power of 478 m W at the wavelength of 2091.06 nm is achieved with a pump power of 16.3 W, corresponding to an optical-to-optical efficiency of 2.9% and a slope efficiency of 7.9%. The single-longitudinal-mode and fundamental transverse mode are less sensitive to the rotating of the corner cube. The results indicate the potential impact of a single-longitudinal-mode Ho： YA G laser with corner cube geometry to improve the anti-maladjustment stability.

A Linearly Polarized Ho:YAG Laser at 2.09 μm with Corner Cube Cavity Pumped by Tm:YLF Laser

A linearly polarized operation Ho： YAG laser at 2090.5 nm with a corner cube cavity is demonstrated. A polarizer with high reflectivity for the s-polarized light at the laser wavelength is employed to achieve a linearly polarized laser. In the same case of resonator length, the corner cube can be used to cut the volume of the Ho：YAG laser and to enhance the stability of the system. The maximum linearly polarized output power of 5.8 W is achieved at the absorbed pump power of 23.3 W, corresponding to a slope efficiency of 29.7%, and the optical-optical conversion efficiency is around 24.9%. The M2 factors of the 2.09μm laser are 2.4 and 1.2 along the horizontal and vertical directions, respectively.

A Mid-IR Optical Parametric Oscillator Pumped by an Actively Q-Switched Ho:YAG Ceramic Laser

We demonstrate a mid-IR ZnGeP2 （ZGP） optical parametric oscillator （OPO） pumped by a dual-end-pumped actively aeoasto-optie Q-switched Ho：YAG ceramic laser. The maximum average output power of 35 W is obtained at a pulse repetition frequency of 20 kHz from the Ho：YAG ceramic laser. Under the maximum incident pump power of Ho：YAG ceramic laser, the maximum output power of 14 W is obtained from the ZGP OPO, corresponding to the slope efficiency of 49.6% with respect to the incident pump power. The wavelength can be tuned from 3.5 μm to 4.2μm （signal）, corresponding to 5.24.1 μm （idler）. The beam quality M2 is less than 2.3 from the ZGP OPO.

High-Power Dual-End-Pumped Actively Q-Switched Ho:YAG Ceramic Laser

We present a high-power Ho：YAG ceramic laser pumped at 1908nm. Using a dual-end-pumped structure, the maximum continuous-wave output power of 48 W is obtained, corresponding to a slope efficiency of 70.4% with respect to the absorbed pump power. At actively Q-switched mode, the maximum average output power of 46 W and the minimum pulse width of 21 ns are achieved at a pulse repetition frequency of 20 kHz, corresponding to a peak power of approximately 109.5kW. In addition, the beam-quality M2 factor is found to be 1.4 at the maximum output power.

Systematic evaluation of a holmium:yttrium-aluminum-garnet laser lithotripsy device with variable pulse peak power and pulse duration

Objective:The Holmium:yttrium-aluminum-garnet(Ho:YAG)laser is the standard lithotrite for ureteroscopy.This paper is to evaluate a Ho:YAG laser with a novel effect function in vitro,which allows a real-time variation of pulse duration and pulse peak power.Methods:Two types of phantom calculi with four degrees of hardness were made for fragmentation and retropulsion experiments.Fragmentation was analysed at 5(0.5 J/10 Hz),10(1 J/10 Hz),and 20(2 J/10 Hz)W in non-floating phantom calculi,retropulsion in an ureteral model at 10(1 J/10 Hz)and 20(2 J/10 Hz)W using floating phantom calculi.The effect function was set to 25%,50%,75%,and 100%of the maximum possible effect function at each power setting.Primary outcomes:fragmentation(mm^3),the distance of retropulsion(cm);
5 measurements for each trial.Results:An increase of the effect feature(25%vs.100%),i.e.,an increase of pulse peak power and decrease of pulse duration,improved Ho:YAG laser fragmentation.This effect was remarkable in soft stone composition,while there was a trend for improved fragmentation with an increase of the effect feature in hard stone composition.Retropulsion increased with increasing effect function,independently of stone composition.The major limitations of the study are the use of artificial stones and the in vitro setup.Conclusion:Changes in pulse duration and pulse peak power may lead to improved stone fragmentation,most prominently in soft stones,but also lead to increased retropulsion.This new effect function may enhance Ho:YAG laser fragmentation when maximum power output is limited or retropulsion is excluded.

Cr,Tm,Ho∶YAG激光器的理论模拟

为了使CTH∶YAG激光器的设计得到更好的优化,从晶体光谱吸收特性、离子间能量转移过程及准三能级运转方式对CTH∶YAG激光器的工作特性进行了理论分析;依据速率方程理论建立了CTH∶YAG激光器运转的理论模型.模拟能量输出与试验结果较好的吻合,验证了此理论模型描述CTH∶YAG激光器运转规律的合理性.模拟结果表明:CTH∶YAG激光器的激光脉冲输出与泵浦有较长的时间延迟且伴随较强的驰豫振荡,冷却温度对激光输出产生较大的影响.

脉冲Ho∶YAG激光对犬多种器官的生物效应

目的 为研究平均功率、照射时间、脉冲能量、脉冲频率等激光参数对Ho∶YAG激光生物效应的影响。方法 我们以犬作为实验对象 ,以不同平均功率、不同照射时间及对相同平均功率的又分为高脉冲能量低脉冲频率 (H)组和低脉冲能量高脉冲频率 (L)组照射皮肤、食管、支气管、胃、膀胱粘膜、卵巢、子宫 ,进行配对研究。结果 肉眼、光镜、电镜观察不同激光参数消融、热凝固作用结果的差异 ,各器官Ho∶YAG激光治疗的安全、有效治疗剂量。结论 脉冲式Ho∶YAG激光的组织表面热凝固作用与平均功率、照射时间成正相关 ;照射时间、脉冲频率恒定时 ,脉冲式Ho∶YAG激光的消融作用与脉冲能量成正比 ;在相同平均功率 ,高脉冲能量低脉冲频率 (H)组的消融作用大于低脉冲能量高脉冲频率 (L)组 ,而热凝固损伤作用小于L组。

Cr,Tm,Ho:YAG激光器温度特性的数值分析

为了分析CTH:YAG激光器在受激跃迁时的温度特性,从速率方程中腔内光子数密度出发,考虑CTH:YAG的准三能级特性以及Tm-Ho准热平衡体系的影响,定义了相对振荡效能参量。采用数值模拟的方法,分析了相对振荡效能的温度特性,得到了其温度变化曲线。结果表明,CTH:YAG的相对振荡效能是温度的非线性减函数,且存在截止温度使腔内振荡无法产生;截止温度与Tm-Ho准热平衡体系的储能成正比,相对振荡效能也随Tm-Ho准热平衡体系的储能的增大而增大。这一结果为CTH:YAG激光器受激跃迁的温度特性提供了理论依据,对改善其工作特性和优化输出结果具有指导性意义。

多路高功率Cr,Tm,Ho:YAG激光器技术

文中介绍了四路Cr,Tm,Ho∶YAG激光器在设定时序下轮流工作,顺序耦合进一根320μm的低OH-石英光纤输出,可以成倍地提高Cr,Tm,Ho∶YAG激光治疗机的输出功率,从而能够适应不同的治疗目的和需要。在三路情况下,当单脉冲最大注入能量为100 J,重频30Hz时,激光器直接输出功率50.17W,光纤末端输出功率35.65W,耦合效率为71%。

重频Cr,Tm,Ho∶YAG激光器输出特性的实验研究

根据对 2 .1 μm波长Cr ,Tm ,Ho∶YAG激光器输出特性的实验研究 ,详细分析了腔长、输出镜透过率、全反镜曲率半径和水温等因素对激光器输出的影响。在镀银腔情况下 ,重频 5Hz时 ,激光阈值为 4 7J,斜效率为 1 .3% ,输入能量为 1 4 4J时 ,最大输出为 7.9W。重频 1 0Hz时 ,激光阈值为 4 5J,斜效率为 1 .1 % ,输入能量为 1 2 1J时 ,最大输出为 9.7W。

Cr，Tm，Ho：YAG激光器输出的实验研究

为了研究Cr,Tm,Ho∶YAG激光器输出脉冲能量和晶体温度的关系,利用有限元的方法计算了不同制冷温度和抽运功率情况下晶体内温度的分布,从而分析温度分布对激光实验输出的影响。控制制冷液温度在15℃、重频5Hz时,获得最大能量为217m J的脉冲输出,斜效率约为1.4%;而重频10Hz时,最大单脉冲输出仅为56m J,斜效率约为0.9%。结果表明,制冷温度和频率的增加都将大大增加激光的抽运阈值,同时降低输出效率。

Ho:YAG激光治疗膀胱癌

为评价ＨｏＹＡＧ激光照射治疗膀胱癌的疗效，用ＨｏＹＡＧ激光对１２４例膀胱癌患者的９２１只肿瘤作３８２次治疗，其中一次治疗近期痊愈者５３例，一次治疗近期痊愈率４２．７％；二次者２４例，二次治疗近期痊愈率１９．４％；三～四次者２３例，三～四次治疗近期痊愈率１８．５％；五次以上者２１例，五次治疗近期痊愈率１６．９％。平均治疗３．０８次。随访１月～３年，复发率为１０．５％，再生率为２４．３％。无１例出现术后膀胱穿孔、出血和输尿管狭窄等并发症。本方法有手术操作安全、简便。

掺Cr^(3+),Tm^(3+),Ho^(3+)离子的YAG晶体的光谱性能

作者测试了Ｃｒ３＋，Ｔｍ３＋和Ｈｏ３＋离子在ＹＡＧ晶体中的吸收谱、荧光谱及荧光衰减寿命。计算了Ｃｒ３＋向Ｔｍ３＋和Ｈｏ３＋及Ｔｍ３＋向Ｈｏ３＋的能量转移效率。表明在（Ｃｒ，Ｔｍ，Ｈｏ）：ＹＡＧ晶体中由于加入Ｃｒ３＋，Ｔｍ３＋离子，使Ｈｏ３＋离子被敏化，荧光强度增大。（Ｃｒ，Ｔｍ。

经鼻腔Ho-YAG激光造孔治疗泪囊鼻腔吻合术后粘连复发的疗效分析

目的 评价利用 Ho- YAG激光治疗泪囊鼻腔吻合术粘连复发的效果。方法 对 12例 (13只眼 )泪囊鼻腔吻合术粘连复发患者进行 Ho- YAG激光治疗 ,观察 6月～ 3年的治疗效果。结果 有 10例 (11只眼 )泪溢消失 ,泪道冲洗通畅 ,治愈率为 84 .6 % ,1例 (1只眼 )泪溢减轻 ,泪道冲洗狭窄 ,有效率为 7.7% ,1例 (1只眼 )泪溢未减轻 ,泪道冲洗阻塞 ,无效率为 7.7%。结论 经鼻腔 Ho- YAG激光造孔是治疗泪囊鼻腔吻合术粘连复发的一种有效的方法 ,而且操作方便 ,患者痛苦小。

Cr,Tm,Ho:YAG激光器耦合效率与束腰关系实验研究

热透镜效应对大功率激光器的光纤耦合系统起着明显的作用。Cr,Tm,Ho:YAG激光器输出的光束为多模光束,文章通过计算不同光束质量和散角的光束的束腰直径和束腰位置,对系统透镜的焦距进行优化计算,实验证明,修改后的光纤耦合系统的耦合效率相对原耦合系统有明显提高,耦合后的光纤末端输出能量明显提高,在使用小孔径的光纤时,可以获得更高能量的输出。