This article is intended to act as an introduction to a session on high technology and the prostate. The session includes microwaves, lasers, ultrasound, and cryotherapy and different authors describe these modalities in varied ways. However, there are already a number of approaches that can be used when treating an obstructive prostate gland. Nevertheless there is still a place for researching into new modalities for this condition. This is because the basic problem is a very simple one, the destruction of the obstructing portion of the prostate gland without damaging surrounding structures. Also prostatic surgery is very common and the revenue consequences are enormous. Approximately 400,000 transurethral prostatectomies are performed per year in the USA.

During the past decade, the authors have been involved extensively in the use of local Microwave Hyperthermia (915 MHz) to the prostate, delivered transrectally. The initial purpose was to use local heat (41 degree(s)-44 degree(s)C) in order to treat cancer of the prostate which is a very common problem in western society, responsible for considerable morbidity and mortality. At a later stage, benign prostatic enlargement and chronic prostatitis were included in the clinical studies. A special apparatus was developed for this purpose known as the Prostathermer (Biodan Co.). Treatment was found to be safe, easy to perform, well-tolerated by patients, and effective in bringing about relief in obstructive and irritative symptoms of prostatism, with local regression in cancer patients. Such has been the experience in several hundreds of patients and thousands of treatment with years of follow-up. Similar experience was shared by several other investigators in several countries. Local hyperthermia to the prostate has opened new horizons for urological clinical work and research. For the moment, it should be regarded as a therapeutic option, both by itself and also in conjunction with other forms of treatment for the various pathologies of the prostate.

Transurethral microwave hyperthermia is emerging as an important treatment modality in the management of patients with benign prostatic hyperplasia. The existing transurethral applicators are easy to operate and some have been designed to be disposable. Heating patterns measured in the laboratory and clinically are similar. There is a predictable temperature distribution clinically useful in the immediate periurethral prostate. Results of preclinical studies have been presented.

Transurethral microwave hyperthermia is a new conservative treatment modality for benign prostatic hyperplasia. From April 1989 until July 1990, 104 patients were treated using this method, with a mean post-treatment follow-up of 6 months. Seventy-four patients were admitted with subjective and objective low outflow obstructive parameters. Thirty were admitted because of acute urinary retention. Five to 10 hyperthermia sessions were administered on an outpatient basis during which 915 MHz microwaves were delivered to the prostate. In the group of patients with a bilobular hyperplasia, an improvement of the total FDA symptom scale with at least 5 points was noted in 60% after 6 months. Major improvement was noted in obstructive symptoms. Those patients with a trilobular hypertrophy showed an improvement in 40%, for a median bar obstruction 28.6% and for medium lobe hyperplasia 41.1%. The most important improvement in the mean average flow and mean peak flow was also noted in the patients with bilobular or trilobular hypertrophy. In both groups a slight decrease of postvoiding residual urine was noted. In those patients with acute urinary retention, 17 out of 23 with a bilobular hypertrophy regained spontaneous micturition. All of those with a median lobe or median bar obstruction required operation. During treatment the patients experienced bladder spasms, perineal pain, and minor urethral bleeding. Approximately 10% of patients had symtomatic urinary infection, which responded well to an appropriate therapy. Post hyperthermia histologic examination of the prostate revealed myonecrosis and thrombosis of the superficial blood vessels with fibrotic reorganization which seemed to be completed three weeks after the end of treatment. This suggests that transurethral microwave hyperthermia induces shrinking of the periurethral prostatic tissue and lowers the static outflow obstruction component.

A percutaneous, low power, interstitial method of controlled tissue coagulation by laser light has been developed and assessed as a possible alternative to existing therapy for benign and malignant prostatic disease. For prostate cancer this technique may be of importance when the tumor volume is small and well defined, particularly as these tumors can increasingly be identified by transrectal ultrasound (TRUS) and are unlikely to have metastasised. The possibility therefore arises of destruction of such small lesions in situ, thereby avoiding the need for radical surgery or radiotherapy. Using the male beagle prostate model, one or more 150-400 micron fibers was implanted within the substance of the prostate through which a Yttrium Aluminum Garnet (YAG) laser energy could be transmitted. Using long exposures and lower powers than used in routine endoscopic laser therapy, well-defined areas of coagulative necrosis could be created without extensive tissue charring or damage to the fiber. For an energy dose of 1000J a lesion approximately 1 cm in diameter results at four days. The ultrasound scanning methods can detect the fiber(s) and the area(s) of coagulation. At 6/52 months following treatment, healing was by fibrosis or cystic degeneration. There were no ill effects on the subjects following coagulation of the prostate. Multiple fiber experiments produced larger volume lesions relevant to more extensive cancer or for the coagulation of benign adenomatous hyperplasia causing outflow symptoms. Ultrasound guided clinical treatments in patients with cutaneous metastases or hepatic and pancreatic tumors have confirmed the experimental results so far obtained. The technique may prove of value for the destruction of early, small, focal tumors of the prostate and for the treatment of moderate benign enlargement. Clinical trial for both benign and malignant disease has commenced.

Transurethal laser prostatectomy, using a 600-(mu) laser quartz fiber capable of directing the laser energy at 90 degree(s), a neodymium: YAG laser, and conventional cystoscopic equipment was satisfactorily performed in dogs. Urinary continence was preserved. Preliminary studies suggested an optimum power setting of 60 W delivered for 60 seconds at four quadrants (12, 3, 6, and 9 o'clock positions). In these animals, the technique provided a simple and safe procedure and did not require catheter drainage.

A transurethral ultrasound-guided Nd:YAG laser delivery system has been developed for use as an alternative approach to the treatment of benign prostatic hyperplasia. The TULIP system has been extensively tested in canine models and is currently undergoing FDA trials in humans.

Cryosurgical ablation of the prostate is a technique that has been enhanced by recent technological advances such as transrectal ultrasonography and fiber optics. Preliminary information suggests that it can be performed safely with less morbidity than the literature previously records. Our preliminary results consist of six patients. No complications have been noted in eight cases (2 patients were done twice). Prostatic biopsy on two of the three patients who could be evaluated show no evidence of cancer. All six showed histologically

Fifty-nine males with bladder outlet obstruction were treated with transurethral ultrasonic aspiration of the prostate. Utilizing a 26.5 French urethral sheath, surgery was accomplished with a 10 French, 0-700 micron vibration level ultrasonic tip with an excursion rate of 39 kHz. Complete removal of the adenoma was accomplished, followed by transurethral electrocautery biopsies of both lateral lobes to compare pathologic specimens. One-year follow-up revealed satisfactory voiding patterns in 57 of 59 men (96%). Two men developed bladder neck contractures. Pathologic comparisons showed 100% correlation between aspirated and TUR specimens (56 BPH, 3 adeno-carcinoma). Forty-sevel men were active sexually preoperatively (6 with inflatable penile prostheses). Post ultrasonic aspiration, 46 men had erectile function similar to preoperative levels with one patient suffering erectile dysfunction. Forty men (85%) had antegrade ejaculation while 7 (15%) experienced retrograde or retarded ejaculation. No patients were incontinent.

High-intensity focused ultrasound has been used experimentally to ablate hepatic, brain, and subcutaneous tumors without damaging adjacent tissues. We report our pilot experience in dogs using this modality to ablate prostatic tissue. Six dogs subjected to acute injury were sacrificed one hour after focused ultrasound ablation; four dogs subjected to chronic injury were sacrificed two, four, six, and twelve weeks post ablation. The pathology of the acute injury and chronic response to this injury is presented. High-volume ablation was created without injury to adjacent tissue. Grossly, the post-ablation prostate appears identical to the posdt-TUR-P defect. Subsequently, a combined imaging/therapy transrectal transducer has been developed and has been used in six dogs. The size and appearance of this probe is similar to current commercially available transrectal imaging probes. Prostate ablation was successful in all dogs and no injury to the rectal wall was apparent when energy levels were appropriate. Again, the post ablation prostate resembled a TUR-P defect. The implications of these findings using this new modality are potentially immense. Plans for human trials are being formulated.

This paper describes laser irradiation in the prostatic adenocarcinoma of stage A. Prostatic adenocarcinoma is an unsuspected prostatic tumor, incidentally discovered during an hystologic examination after TURP or adenectomy, limited to the prostate. Sixteen patients with hystological diagnosis of prostatic carcinoma of stage A (12 A1 and 4 A2) entered the trial. After ultrasound control of the reduced prostatic tissue to a thin residual capsule an endoscopic and percutaneous irradiation with endoscopic Nd:YAG laser was performed. Average follow-up is 18 months (range 6-48). All patients had negative biopsies. No tumor had progressed. There were no side effects, both potency and continence were unchanged. The results are promising and comparable to short-term results obtained with conventional treatment.

This paper describes the extended endoscopic treatment of early prostate cancer. A 'radical' TURP under ultrasound control leaves residual prostatic capsule 6 mm or less in depth. If the resected tissue includes prostatic cancer (

The authors investigate the laser induced fluorescence spectroscopy of prostate tissue.

In 1988, the KTP-532 laser was used to ablate a series of benign urethral strictures. Rather than using a single incision, as in urethrotomy, strictures were treated with a 360$DEG contact photoradiation. Thirty-one males, average age 53.2 years, received 37 treatments. Six patients underwent a second laser treatment. Stricture etiology was commonly iatrogenic (32%), traumatic (16%), and post-gonococcal (10%). Stricture location included mainly bulbar (49%), membranous (20%), and penile (12%) areas. The surgical technique consisted of a circumferential ablation followed by foley catheter placement (mean 10 days). Follow-up on 29 of 31 patients ranged from 1 to 16 months (mean 9.7) Complete success occurred in 17 patients (59%) who had no further symptoms or instrumentation. Partial success was seen in 6 patients (20.5%) with symptoms but no stricture recurrence. Six patients (20.5%) failed therapy requiring additional surgery or regular dilatations. No complications were encountered. Although longer assessment is required, KTP-532 laser ablation of urethral strictures appears efficacious.

The Nd:YAG laser treatment of a 32-year-old man affected by azoospermia is presented. Preoperative evaluations showed fructose absence in the ejaculate and transrectal echothomography showed bilateral seminal vesicles dilatation. Before the surgical procedure a transperineal vesicledeferentography echographycally guided was carried out. The exam showed the absence of ejaculatory duct and the presence of cystic dilatation in which both seminal vesicles joined. During the exam a mixture of contrast medium and methylen blue was injected into the seminal vesicles. Later, transurethrally and by means of a sapphire contact tip, a new channel, over the veru montanum, was created by a Nd:YAG laser irradiation (25 Watts/2 seconds). The irradiation was carried out until an efflow of seminal material mixed with blue came out through the new channel. Ten months later the patient has 32.106/ml spermatozoa with good quality of semen analysis.

Laparoscopic pelvic lymphadenectomy has become increasingly of interest to Urologists in staging patients not only with prostatic carcinoma but for those patients suffering with carcinoma of the bladder. It also allows access for therapeutic treatment such as treatment of varicoceles and laser phototherapy for transmural coagulation of bladder cancers. Lasers have proven extremely better in allowing surgical incisions through the laparoscope and coagulation of bleeders. Both the KTP and Neodymium Yag Laser have been used for this purpose. The KTP Laser has distinct advantages in that it allows 1) flexible fiber easily used through laparoscopes, 2) the ability to coagulate and cut retroperitoneal tissue, and 3) seal lymphatics when lymph nodes are removed. The KTP fiber can be used to incise the retroperitoneum to expose the lymph node tissue. Grasping the lymph nodes with forceps, the laser can excise and coagulate the proximal and lymphatic channels. The laser fiber will not experience carbonization as can occur with the Yag Laser fiber unless a contact tip sapphire end is utilized. The KTP's laser fiber ability to give coagulation and ablation of tissue through a liquid medium allow it to be an excellent choice for laparoscopic pelvic lymphadenectomy.

Following a series of opto-acoustic-mechanical and spectroscopic studies into the basic mechanisms of laser lithotripsy, a plasma-mediated opto-mechanical energy transfer model is presented. Laser energy, first absorbed by the calculi material at the surface and couples into the initiated plasma following ionization of vaporized material, is finally transformed into destructive mechanical energy via a shock wave induced by the impulsive expansion of the resulting plasma. This leads to the fragmentation of the calculi. The laser-plasma energy coupling gives a new definition for the fluence threshold to laser induced breakdown, which agrees with shock wave detection and analysis. A laser pulse shape with initial low intensity and sufficient fluence to vaporize a required amount of target material (lasting a few microsecond(s) ) and terminating in a short, intense pulse of about 1microsecond(s) or less, to couple most of the laser energy into the dense young plasma and so create high pressures, is required to produce optimum effect for laser lithotripsy. An opto-mechanical coupler has been designed which transfers the maximum laser energy into mechanically destructive energy, and successfully fragments various types of urinary and biliary calculi even including those calculi with poor surface absorptance, like pure white cystine. A solid state laser, Ho:YAG (2.1 micrometers wavelength and 150 microsecond(s) pulse width), has also been tested as an alternative to the flashlamp-excited dye laser. The underwater shock wave induced by this laser has been measured and has successfully fragmented calculi with poor absorptance in the visible region.

A spectroscopic stone/ureter identification system is already in clinical use for pulsed dye laser lithotripters (590 nm). Alexandrite lasers are believed to be a solid-state laser alternative to pulsed dye lasers in lithotripsy. We investigated different spectroscopic stone/ureter detection schemes for the q-switched alexandrite laser (750 nm and 375 nm), including plasma detection, spectral LIF analysis, and time resolved LIF intensity analysis. Additionally, we investigated the possibility to identify different stone types using laser induced fluorescence exited at UV wavelengths.

Laserlithotripsy in association with flexible or semirigid 'miniscopes' is gaining increasing importance for ureteric stone therapy. So far, the Nd:YAG and the pulsed dye-laser have been used for laser lithotripsy in clinical applications. For both systems good results have been reported for most urinary calculi and no relevant side effects could be demonstrated in experimental and clinical use. Since both systems, however, have their specific drawbacks, the new solid-state Alexandrite laser was developed to combine the advantages of the two existing lithotripsy lasers. The results of in vitro and in vivo evaluation as well as the first clinical experiences of this new system show that it is comparable in respect to the lithotriptic potential in vitro and the lack of long-term side effects in vivo. The combination of a solid state laser that can utilize 200 micrometer quartzfibers for lithotripsy will prove advantageous in the clinical routine.

Alexandrite laser system which emits a wavelength of 750 nm has been recently proposed as a substitute for the pulsed-dye laser (504 nm) for laser-lithotripsy. We have carried out in vitro lithotripsy trials in order to evaluate the efficiency of a flashlamp pumped Q-Switched Alexandrite laser. The experimental system was performed by an alexandrite laser (Quanta-System Inc.), with a pulse energy between 40-80 mJ/pulse, at a repetition rate of 10-20 Hz; and a pulse duration of 250-300 nsec. This system permits the use of 320-500 micrometers fibers.

To minimize urotherial tissue injuries by false laser irradiation during the laser stones fragmentation, a novel fiber-optic analytical system was developed which was able to distinguish urotherial tissues from urinary stones in vivo. This system was composed of the fiber-optic pulsed photo-thermal radiometry (PPTR) system together with a thin-fiber endoscope. The ultraviolet Ar laser was employed as the excitation light source. The catheter of this system was 6F in diameter and consisted of SiO2 glass fiber (400 micrometers (phi) ) as an excitation line, an As-S glass fiber (400 micrometers (phi) ) as a detection line, and a thin-fiber endoscope (610 micrometers (phi) ). A urinary stone was introduced into the canine ureter uneter under general anesthesia. The catheter system was inserted through an opening of the ureter distal to the stone. The e-folding decay time of the PPTR waveform of which optical and/or thermal properties of the tissues and stones were characterized was measured in vivo. The e-folding decay times were significantly different between urinary stones and the canine ureter. These results suggest that the fiber-optic PPTR analysis might be significantly useful procedure to prevent urotherial tissue from false irradiation injuries in clinical laser stone fragmentation.

Abstract not available.

The intracorporal lithotripsy of ureter stones using laser pulses with a duration of 8 to 20 ns is carried out by means of energy converters. These devices have the purpose to transform the optical energy of the laserlight into mechanical energy of shockwaves, which cause the intended stone fragmentation. Therefore this method is independent of any optical property of the stone. For the endoscopic lithotripsy a continuous flow of irrigation liquid must be supplied to ensure a clear field of view and to transport the small stone fragments out of the body. In the case of the method developed by us, a second function is appointed to this liquid: the energy conversion. In transparent liquids, conversion of the optical energy is done by the laser-induced breakdown (LIB), which produces mechanical shockwaves. To release such a LIB, the laserpulse intensity must exceed a certain threshold. To achieve a LIB in the liquid at the fiber exit there are two possibilities. First, the fiber exit is spherically shaped, which leads to a kind of focus between fiber and stone. Second, the threshold intensity of the liquid is lowered. This is performed by addition of minimal amounts of Fe+++-ions. To obtain a stable and physiologically applicable irrigation solution the Fe+++-ions were added to isotonic saline solution in form of a dextran complex.

The mid-infrared pulsed Holmium lasers operating around (lambda) approximately equals 2 micrometers are gaining more and more significance for numerous medical applications especially due to the ability to transmit the IR laser energy via recently available fiber-optic delivery systems. This paper describes a rotating mirror Q-switched Cr:Tm:Ho:YAG-laser ((lambda) equals 2.12 micrometers ) generating pulse durations in the microsecond(s) region. Pulse lengths up to 10 microsecond(s) have been achieved. This time domain is expected to offer several advantages for medical applications compared to the free running pulse length of around 300 microsecond(s) as well as to the 200 ns unstretched Q-switched pulse duration. Shock waves produced by laser induced plasmas have been investigated and analysed with these pulses and the fiber fragmentation resulting from the optical breakdown at high power densities was evaluated.

In the past a widespread use of pulsed solid-state and flashlamp-pumped pulsed dye lasers in the vast medical field of endoscopic laser-induced shock wave lithotripsy (LISL) of urinary, biliary, and salivary stones was hindered mainly by the facts that (1) the available systems were too expensive compared to other conventional therapies; (2) the laser systems of the first generation didn't ideally fit into existing operation rooms because they were bulky and heavy; (3) the laser systems--except for the non solid-state dye laser system--provided only a fixed wavelength for stone fragmentation. This paper reports on a new concept of a small size pulsed and tunable alexandrite laser system for laser-induced shock wave lithotripsy that could provide not only wavelengths in the fundamental region of 720-860 nm with high peak powers and high energy fluences but also in the frequency-doubled region of 360-430 nm. The fragmentation process is induced via the violet wavelengths and the fragmentation efficiency is reinforced via the fundamental wavelengths of the laser system.

Laser lithotripsy (LISL) in combination with a bare fiber can lead to fragmentation of the fiber tip. Fiber fragmentation of four lithotripsy laser systems was measured under clinical conditions (calcium sulphate stone, covered with water), a Q-Switched Alexandrite laser, a pulse-stretched alexandrite laser, and two different dye lasers were used. The threshold for fiber fragmentation for pulses of Gaussian shape was 200 MW/cm2 peak power density. The Q-Switched Alexandrite laser leads to fragmentation rates of 100mm/1000 pulses at typical pulse-energies (50mJ, 150ns), whereas fiber fragmentation did not occur if dye lasers were used (80 mJ, 1.3 microsecond(s) ; 80 mJ, 2.5 microsecond(s) ) due to their longer pulse-lengths and lower power densities respectively. Using a pulse-stretched alexandrite laser fragmentation could be avoided if pulse lengths above 1 microsecond(s) were used. During LISL the fiber fragments which are produced will be embedded in the ureter wall and therefore subsequent formation of stenoses may be possible.

This paper describes preliminary experimental data of kidney stone fragmentation by the laser induced shock acoustic pulses. Acoustic pulses were produced in a thin layer of liquid as a result of absorption process of 1.06 micrometers radiation pulses. The phosphate Nd:glass laser operated in a pulse Q-switched regime with the pulse energy up to 10 J and pulse duration $OM 30 ns. The pressure induced by acoustic pulses on stones surface was reached up to 1-2 kbar in focal area, that was sufficient for stone destruction.

This paper describes the experimental investigation of the fragmentation processes of urinary stones by Cr,Nd:YSGG laser radiation (2.79 micrometers ). The laser operated in a pulse free-running regime with the pulse energy up to 1 J and pulse duration of 250-550 micrometers . It was shown that about 3 kJ of total radiation energy was required in order to ablate 1 g of urinary calculus. In those conditions, the stone substance was broken in a small fibrous-like dust. The maximum size of particles did not exceed 0.2-0.4 mm. The qualitative comparison of the stone ablation efficiency for the Cr,Er:YSGG laser, Cr,Nd:YSGG laser (1.06 micrometers ), and Cr,Tm,Ho:YSGG laser (2.09 micrometers ) was carried out.

The rapid growth of laparoscopic cholecystectomy and other laparoscopic procedures has created the need for simple, secure techniques for laparoscopic closure without sutures. While laser tissue welding offers one solution to this problem, concerns about adequacy of weld strength and watertightness remain. Tissue solders are proteinaceous materials which are placed on coapted tissue edges of the tissue to be closed or sealed. Laser energy is then applied to fix the glue in place completing the closure. Closure of the choledochotomy following a laparoscopic common duct exploration is one potential application of this technique. Canine longitudinal choledochotomies 5 mm in length were sealed using several laser glues and using the 808 nm diode laser. Saline was then infused until rupture of the closure and peak bursting strength recorded. Fibrinogen glue provided moderately good adhesion but poor burst strength. Handling characteristics were variable. A viscosity adjusted fibrinogen preparation produced good adherence with mean weld strength 264 +/- 7 mm Hg. The clinical endpoint for welding was a whitening and drying of the tissue. New laser solders can provide a watertight choledochotomy closure of adequate immediate strength. This would allow reliable, technically feasible common bile duct exploration via a laparoscopic approach.

A common cause of morbidity in patients recovering from bowel surgery is leakage from colonic anastomoses. A technique utilizing a laser activated protein solder to strengthen colonic anastomoses in a canine model was evaluated. Following creation of six single-layer interrupted suture anastomoses in four dogs, a protein solder consisting of indocyanine green dye and fibrinogen was topically appied to the serosal surface and exposed to 808 nm continuous wave diode laser energy. Immediately following anastomosis, the mean leakage pressure of sutures alone was 129 +/- 14 mm hg (n equals 6), while the mean leakage pressure of sutures reinforced with the laser welded solder was 312 +/- 32 mm hg (n equals 6) (p <0.001). Histologic examination of sections take through the anastomosis demonstrated a layer of fibrinogen across the anastomotic gap without evidence of thermal injury. Laser activated protein solder significantly enhances the immediate strength of sutured colonic anastomoses without causing appreciable thermal injury to surrounding tissues.

Most general surgeons are familiar with monopolar electrocautery, but few are equally comfortable with laser dissection and coagulation. At courses across the country, surgeons are being introduced to laparoscopy and laser use in one and two day courses, and are certified from that day forward as laser laparoscopists. Some surgeons are told that laser and electrosurgery may be equally acceptable techniques for performance of laparoscopic surgery, but that a surgeon may double his patient volume by advertising 'laser laparoscopic cholecystectomy.' The sale of certain lasers has skyrocketed on the basis of such hype. The only surprise is that laparoscopic cholecystectomy complications occurring in this country seem to be more closely related to the laparoscopic access and visualization than to the choice of laser of electrocautery as the preferred instrument for thermal dissection. The purpose of this article is to: 1) Discuss the physics and tissue effects of electrosurgery and laser; 2) compare the design and safety of electrosurgical and laser delivery systems; and 3) present available data comparing laser and electrocautery application in laparoscopic cholecystectomy.

Pelvic node dissection has gained widespread acceptance as the final staging procedure in patients with normal acid phospatase and bone scan free of metastatic disease prior to definitive therapy for cure. However, the procedure has had a high morbidity (20-34%) and a major economic impact on the patient due to lengthy hospitalization and recuperative time. The development of laparoscopic biopsy techniques suggests that the need for open surgical lymphadenectomy may be reduced by a laparoscopically performed lymphadenectomy. The goal of this report is to investigate the possibility of laparoscopic pelvic lymphadenectomy in an animal model. Our interest in laparoscopy is based on the ability of this technique to permit tissue removal without the need for major incisions. In laparoscopic cholecystectomy and laparoscopic appendectomy, the surgical procedure is essentially unaltered. The diseased organ is removed and there is no need for a large abdominal incision.

The accurate and timely diagnosis of acute appendicitis remains a difficult clinical dilemma. Misdiagnosis rates of up to 40% are not unusual. Laparoscopic appendectomy provides a definitive diagnosis and an excellent method for routine removal of the appendix with very low morbidity and patient discomfort.

This paper is to report and analyze our clinical experience in ap].ying endosoopi. c Nd:YAG laser to treat 451 esophagostenoses (1197 peraon times) including all kinds of then. All kinds of esophagostexiosis were mainly characterized by having difficulties swallowing foods. Some of their esophagus were even oompletely obstructed and could not drink even a drop of water On the basis of experint&xts in animals, fresh organs of the body, we started to treat all kinds of esophagostenosis with endoscopio Nd:YAG laser in 1985. By the end of 1989, 451 patients bad been treated in our hospital. Boh the patients and we felt satisfactory with the results we gain.

Interest in lasers has increased exponentially due to the meteoric growth of laparoscopic cholecystectomy. This paper reviews the laser technologies available for laparoscopic use. The relative merits and liabilities for each wavelength and delivery system are discussed. Considerations for future developments of these technologies are provided.

Nineteen patients with upper tract filling defects were studied in order to determine their clinical diagnosis. In nine patients ureteropyeloscopy confirmed the presence of urothelial tumors of the upper urinary tract. In all the patients ureteroscopy and cold biopsy apparently localized low grade tumors. All the patients underwent Nd:YAG laser irradiation of the tumor and of the base utilizing 25-30 Watts for 3 sec. During the follow-up the patients had endoscopic surveillance every three months (average follow-up is 12 months). Ureteropyeloscopy seems to be an accurate form of evaluation and management of all upper urinary tract filling defects. It permits endoscopic access into ureter and renal pelvis, and coupled Nd:YAG laser it allows, in the same session, treatment of primarily low grade-low stage tumors by conservative approach and endoscopic means.

Dehiscence rates of esophageal anastomoses range between 5 and 20%. Causative factors include ischemia, tension, foreign body reaction, microabscesses, and the negative pressure within the thoracic cavity. Laser assisted tissue sealing (LATS) has been shown to decrease anastomotic leakage rates in other tissues. Using a canine model the efficacy of LATS in enhancing single layer hand swen intrathoracic esophageal anastomoses was assessed. Via a left thoracotomy, paired two centimeter transverse incisions (one laser sealed, one control) were made in the proximal and distal esophagus in nine dogs. Both were sewn using a single layer of 4-0 polyglycolic acid. A combination of albumin (0.2 cc), sodium hyaluronate (0.4 cc), and indocyanine green (1 gtt) was applied to one of the randomly chosen hand sewn repairs. The albumin/hyaluronate combination is used to provide a protein matrix across the anastomosis for ingrowth of fibroblasts. Indocyanine green dye selectively absorbs at $OM805 nm which matches the output of the diode laser (808 +/- 1 nm), thus improving uptake of laser energy by the targeted tissues. The anastomosis was then exposed to continuous wave diode laser energy for $OM2 minutes at a power density of 9.6 W/cm2. The esophagus was recovered either at the time of sealing or two days postoperatively and infused with saline under pressure. Bursting pressures were considered the point of initial saline leakage. At time 0 there was no significant difference in bursting pressures between the LATS group and controls. However, at two days postoperatively controls burst at 121 +/- 14 mmHg while the laser assisted anastomoses burst at 295 +/- 35 mmHg (p < .005). HPS staining of uninjured portions of the laser sealed anastomoses revealed minimal thermal injury to the mucosal surface initially, with some regeneration of mucosal lining at two days postoperatively. No foreign body reaction to the solder was noted. Laser reinforcement of single layer hand sewn esophageal anastomoses appears to increase bursting pressure and may result in reduced incidence of anastomotic leakage.