The use oflasers in urology has dramatically escalated over the past year as urologists learn that this approach allows prostate surgery on an outpatient basis, saving valuable time for the surgeon and reducing costs to the healthcare system. With over 400,000 BPH cases treated each year, laser technology is being assimilated into a high volume market that is already having a positive financial impact on the suppliers. However, competition from entrenched electrosurgery manufacturers is intense, and conservative elements in the urology medical community have attempted to block adoption ofthis innovative technology. We will discuss the various laser products available for BPH treatment, as well as the research and regulatory status of each system. In mid 1993 the FDA implemented stringent rules that put more teeth in earlier warnings. Specifically, the agency ruled that all laser devices intended for the treatment ofBPH must go through a lengthy Pre-Market Approval (PMA) process. Given the current rate ofPMA reviews, marketing clearance for this indication could take several years —iftheAdvisory Panel finally decides that lasers are safe and clinically effective. CR. Bard was the first company to file a PMA application (June 1993) for treatment ofBPH with the Urolase fiber. Data was collected from six investigational sites, with a one-year followup study. The FDA distributed formal guidelines for clinical investigations of BPH fibers earlier this year, but it is not clear how many suppliers of laser fibers have obtained IDE's and implemented scientific studies. Faced with the uncertainties and costs of this regulatory path, some companies may simply decide to do nothing. Additional enforcement actions by the FDA are focused on halting the liberal sale of fibers under general urology 510(k) clearances that nearly all companies have obtained [See ML!, April 1993). Reportedly, the agency is in the process of notifying manufacturers regarding specific limits on the use ofthese products. Until now, several companies have been actively selling fibers and tramingurologists touse these devices inprostatectomy procedures. By avoiding anylabeling referring to BPH, fibers are sold in a "grey market" that caters to users who abhor government control ofmedical practice. Ironically, this grey market represents the largest single market for surgical laser products at this time. As ifthe regulatory repression ofprostatectomy fibers wasn't bad enough, various regional Medicare carriers have been denying reimbursement for laser procedures. Most recently, Blue Cross of Northern California decided not to pay claims for laser procedures until FDA marketing clearance comes through. A survey oflaser users throughout the country reveals a great deal of confusion and fears. While hospitals are financially motivated to increase utilization of installed surgical lasers, many urologists are afraid that insurers may deny reimbursement oftheir professional fees —or even demand return of payment already made. In the final analysis, it remains to be seen whether urologists will still be interested in laser technology if and when it becomes approved. Given the certainty of broad Medicare cutbacks, and the uncertainty of reimbursement levels for the laser procedure, the economic factors that currently drive physician interest laser treatment of BPH [See MLI, June 1993] may not apply in the future. Moreover, the negative signals provided by ongoing patent litigation, financial instability, and our industry's history only serve to make laser use less appealing. Currently, all of our hopes regarding the potential market for laser BPH products seem to center on C.R. Bard. If this company emerges from the PMA process before the window of opportunity closes and rekindles the interest of urologists, then they deserve much credit for salvaging this market for the medical laser industry.

Abstract not available.

A long term prospective randomized trial comparing Visual Laser Ablation of the Prostate (VLAP) to Transurethral Resection of the Prostate (TURP) was begun in August, 1991. The short term follow-up results have been presented with the findings that there was no statistically significant difference in the objective and subjective improvements in patients following either operative procedure. These studies also have revealed the complication rate to be significantly less than the reported complications following TURP. The patients who met routine pre-operative surgical criteria for the relief of bladder outlet obstruction secondary to benign prostatic hyperplasia were randomized prospectively into two groups. These groups were subsequently followed post-operatively with AUA symptom scoring, post-void residual urine and peak voiding flow rates. These results were compared to their pre-operative evaluation and followed for 18 months. The long term data indicates that the patients continued to enjoy significant objective and subjective improvement comparable to that following TURP. The complication rates are significantly reduced compared to TURP. This indicates that the improvements noted following VLAP are durable and continue to be maintained after an eighteen month follow-up.

This report will elaborate on the results of higher power density lesions. Right angle fibers at 80 to 95 watts power were used in near contact or contact, and all cases were monitored on transrectal ultrasound and performed on video. Six month postoperative results on forty-nine evaluable patients revealed changes in AUA symptom scores from a mean of 21.7 to 8.6, peak flow rates improving from a mean of 8.3 to 19.9 mL/second and mean flow rates improving from 4.1 to 10.2 mL/second. These results compare favorably to those of a standard TURP. Complications and adverse events were negligible.

Laser Prostatectomy has become popular with many Urologists because it is associated with a lower morbidity than transurethral resection (TURP). It is however unknown for how long the procedure will remain efficacious. The TURP has been shown to require redoing after an average of 15 years. In this paper three conceptually different approaches will be discussed using even more varieties of delivery device.

The aim of our study was to systematically determine the effect of Nd:YAG laser in the prostatic tissue of a canine animal model and to define the correlation of laser dose with the depth of coagulation necrosis. This study was carried out with a right angle non contact laser delivery system.

In this study, the optical and thermal characteristics of the various commercially available devices for treating benign prostatic hyperplasia, using transurethrally delivered Nd:YAG laser light, were evaluated. To calculate the optimal parameters for each delivery system, the created tissue effect was dynamically modeled. Optically the devices were evaluated using by measuring the 3D irradiance distribution in a water environment. The thermal behavior of the devices was studied by a specially developed thermal imaging technique. The optical and thermal characteristics of the devices together with optical and thermal parameters of prostatic tissue were used as an input for a theoretical model to predict the extent of laser induced permanent damage and thus the effect of the device. Results show the influence of beam profile, spot size and secondary reflections of each laser prostatectomy device and modeling its therapeutic effect, will contribute to obtain an optimal dosimetry with best fitted parameters for each individual device.

Laser prostatectomy is an alternative to conventional surgical resection. However, clinical studies lack sufficient power to determine optimal exposure parameters. This paper describes axi-symmetric and 3D finite element models of heat transport in laser irradiated tissue. These models have been verified with an analytical solution for a laser with a Gaussian beam profile using both stationary, and scanning laser beams. Percent errors between the analytical solutions and the finite elements solutions were less than 7%. Further development of these models will facilitate optimization of laser prostatectomy methods.

Normally, a laser prostatectomy to treat Benign Prostatic Hyperplasia is performed using a fixed dosimetry. Differences in, e.g., blood flow, optical properties and geometry, are not taken into account, although most of these differences may be distinguished when performing a cystoscopy, e.g., the color of the prostate. These characteristics show their influence in the final tissue effect. We developed a model to predict the permanent damage to the tissue.

We describe here a highly durable 600 (mu) optical fiber with a 20 mm frosted distal tip protected by a smooth transparent cover that is capable of remaining in contact with tissue for prolonged periods. When used with a Neodymium:YAG (Nd:YAG) laser, the active fiber surface diffuses optical radiation in a radial pattern, delivering up to 40 W power, and thus providing consistent and uniform interstitial photothermal therapy. Animal studies in the United States and clinical studies in Europe have demonstrated the feasibility of using these fibers to treat a variety of soft-tissue pathologies, including benign prostatic hyperplasia.

Interstitial laser coagulation of the canine prostate using the Sharplan interstitial thermal therapy fiber (Model 25432) was performed in 9 adult dogs and the subsequent gross and histopathologic changes occurring in the prostate were studied at intervals ranging from 1 hour to 5 weeks. A large well-demarcated area of acute coagulative necrosis developed around each fiber tract which in turn was surrounded by a prominent narrow zone of marked tissue disruption and an outer zone of hemorrhage. Liquefaction developed within the coagulative areas within 24 hours and by 4 days, each prostatic lobe contained an irregular cavity which became lined by normal-appearing transitional epithelium and that by 5 weeks, communicated with the prostatic urethra. These changes, similar to those reported following transurethral visual laser ablation of the prostate, suggest that interstitial laser thermal therapy may provide an alternative means for treating selected patients suffering from prostatic enlargement.

Visual laser ablation of the prostate was performed on 8 mongrel dogs employing a cylindrically diffusing fiber delivery system and a 1.06 neodymium:YAG laser. Each dog received 15,000 J of laser energy delivered to the prostate in one continuous dose of 25 W for 10 min. Gross and histopathologic examination of serial sections of the prostate was performed at intervals from 2 hours to 7 weeks postoperatively. Grossly, a spherical zone of destruction averaging 2.8 cm in diameter was present in all dogs. Histopathologic changes in the prostate consisted of acute coagulative necrosis with interstitial edema at 2 hours, becoming hemorrhagic at 24 hours. A prominent circular area of acute coagulative necrosis with extensive areas of liquefaction and hemorrhage was presented at 4 days. Early re- epithelialization of the resulting cavity was present at 3 weeks with nearly complete resolution 7 weeks postoperatively. We believe that, because of the simplified fiber placement and complete lack of postoperative complications in this small group of dogs, the cylindrically diffusing fiber could offer significant advantage over side fire-style fibers for transurethral prostatectomies.

This paper examines the potential effectiveness of a high power, 810 nm diode laser in inducing thermal coagulation of prostatic tissue. A theoretical study is performed to compare the effectiveness of the diode laser with the currently used Nd:YAG laser (1064 nm) for prostate coagulation. Transurethral diode laser irradiation in a canine model is also performed to examine the efficacy of inducing thermal coagulation in vivo. Model results show that comparable tissue effects can be obtained with both diode and Nd:YAG lasers. The in vivo results indicate that considerable amount of coagulation necrosis of prostatic tissue can be induced by the high power diode laser.

We report preliminary potato dosimetry and canine studies evaluating a new 1,000-(mu) optical fiber whose distal tip has been bent to 45 degree(s), allowing for endoscopic delivery of neodymium:YAG laser energy at an angle of 60 degree(s). Our results suggest that this fiber is comparable with other more complex angled delivery systems; has several advantages: it can deliver greater power over longer time intervals, producing larger volumes of coagulative necrosis, and it may be operated in a contact mode within a fluid medium without fiber `burnout.' This fiber should prove useful for transurethral laser ablation of the prostate.

The contact laser applications for the removal of the enlarged prostate are distinctly different than the majority of non-contact Nd:YAG lasers that rely on coagulation necrosis and delayed sloughing. Contact Nd:YAG laser allows cutting, coagulation and vaporization of tissue with minimal penetration beyond the contact surface. Using the contact laser prostatectomy technique, the contact laser probe directly touches and immediately vaporizes the prostatic tissue under the probe. The net result is the immediate removal of the obstructing tissue, in a manner similar to the standard electrosurgical TURP. This immediate removal of tissue offers the patient treated with the contact laser the potential for decreased catheter time and a more rapid resolution of symptoms. Our initial experience suggests that the contact technique may be better suited for the smaller prostate gland (i.e. less than 30 gm). The contact laser may also be used for a procedure termed the `laser assisted TURP': a standard electrosurgical TURP is performed and the contact laser is used for hemostasis. Several investigators have reported non-randomized results of the contact technique with good outcomes. A prospective randomized trial of the contact laser prostatectomy vrs the electrosurgical TURP is underway. The contact laser vaporization of the prostate holds great promise for the treatment of symptomatic benign prostatic hypertrophy: it is virtually bloodless and allows immediate visualization of the TUR defect.

To develop a new transperineal laser prostatectomy through a biopsy needle, we determined the efficiency of a pulsed Nd:YAG laser irradiation for canine prostate. The Ho:YAG laser ((lambda) equals 2.1 micrometers ) may induced stress-wave to destroy the small vessels in prostate. After the exposure of the canine prostate, it was punctured by the needle. A quartz fiber of which core-diameter was 200 or 400 micrometers was inserted into the 18 G needle. The irradiation fluence was set to 150 - 600 J/cm² and repetition rate was kept at 2 Hz. The cross-section of the irradiated portion of the prostate extracted immediately after the irradiation showed dark-colored hemorrhage layer around the ablation tract with 1 - 2 mm thickness. Some hemorrhage was histologically seen in stoma and gland in the irradiated prostate. In the case of 150 - 175 J/cm² in the irradiation fluence, the irradiated portion of the prostate was found in the wedge-shaped area with brown color at one week after the irradiation. The lymphocytes infiltrating into the wedge-shaped zone were found. The wedge- shaped zone spread over the prostate and the change of urethral mucosa was minimum at one month after the irradiation. In the case of 500 - 600 J/cm² irradiation, the paraurethral cavity was made at one month after the irradiation. The histological examination showed that the hemorrhage and subsequent histological changes may be caused by the laser induced stress-wave rather than thermal effect. Our results suggest that transperineal irradiation of pulsed Ho:YAG might offer an effective treatment for benign prostatic hyperplasia with the minimal damage to the urethral mucosa.

The conventional treatment of the obstructive pelviureteric junction (PUJ) is open surgical repair via a loin incision and a pyeloplasty. A funnel-shaped PUJ is constructed by means of sewing in a flap of pelvis into the proximal ureter or a spatulated anastomosis is performed. Wickham suggested that an incision of the PUJ combined with stenting could be performed by means of a percutaneous approach and would replicate a Davis intubated pyeloplasty. Davis had shown that simply incising a narrow PUJ or ureteric stricture followed by stenting for 6-8 weeks would result in the regeneration of muscle and epithelium around the stent to form an unobstructed new structure. The percutaneous approach had a lower success rate than conventional open surgery. Approximately 30% of cases relapsed. These failures could however also be treated by a second incision and stenting. A less invasive modification of the percutaneous approach is to perform the entire procedure via a ureteroscope. This has been performed using large caliber ureteroscopes and electrical incision. We report here the use of a holmium laser to incise the ureter in combination with a miniaturised ureteroscope. It has been shown that large caliber ureteroscopy carries a high complication rate with strictures and perforations. Miniaturised ureteroscopy is safer and easier.

Transitional bladder cell carcinoma (TCC) is easily recognizable, but for the diagnosis of severe dysplasia and carcinoma in situ (CIS) one can only rely on randomly taken biopsies. Fluorescence tagging of tumors by sensitizing agents such as hematoporphyrin derivatives (HpD) is possible but presents, even at low doses, a number of serious drawbacks for the patient. We demonstrate a cystoscopic fiber optic instrument, based on a small mercury arc lamp, for in vivo demarcation of human bladder carcinoma. The instrument detects the tissue autofluorescence upon UV excitation (365 nm), thus eliminating the need for sensitizing agents. The average demarcation contrast obtained for CIS and TCC is respectively 2.6 and 3.2, which is about 60% higher than what can be expected from photodynamic imaging with low-dose HpD. The main underlying biophysics are derived from a spectral analysis of the observed autofluorescence signals. The integration of the diagnostic method with a reliable therapeutic technique for tumor cell destruction, opens the way for cost-effective preventive care of high-risk patients.

The holmium laser pulsed at 350 microsecond cuts tissue and fragments calculi. It has been assessed for minimally invasive urological intervention. It is useful for partly excising and partly coagulating tumors, incising strictures and the obstructed PUJ. It partly drill and partly fragments urinary calculi however hard. Other lasers are more effective at any one particular application, but this laser is a useful compromise as a multifunctional device.

Laser technology has been applied to intracorporeal lithotripsy for ureteral calculi at several different wavelengths. The most successful of these is the Alexandrite. Development through animal studies, FDA approval, and current use is examined. After 22 months and a study encompassing 175 procedures the device has demonstrated efficacy equal to or surpassing other laser and non-laser methods with equal or greater safety to adjacent soft tissue structures.

The gallium arsenide semiconductor laser can emit in the near infrared where the depth of penetration into tissue is great although scattering is less than with the Nd:YAG laser. The laser is highly compact. It runs off a normal electrical outlet with no cooling requirement. It is therefore quiet and convenient. The laser has been assessed in a wide variety of applications in our urological department.

Seventy patients with 316 tumors of urinary bladder have been treated by high power gold vapor laser with HPD photodynamic therapy in this hospital. All cases were histopathologically diagnosed as transitional cell carcinoma, T1-T3 stage and all are recurrent ones. HPD was administered intravenously 48 hours before the treatment (5 mg per kg of patient weight) and irrigated into bladder 2 to 4 hours (2.5 mg per kg of patient weight) before the treatment. The power calculated was 70.8 - 509.6 mw/cm per pulse. The pulse energy was 0.5 mJ per pulse and the repetition rate was 6000 - 9000 Hz. Both the tumors and whole bladder were irradiated through the fiber inserted in the bladder by cystoscope. The results of a follow-up from 4 to 46 months are as follows: cured 54 (77.14%); good effect 12 (17.14%); improved 4 (5.7%). Regrowth occurred in only 8 cases (11.43%) between 3 to 14 months.

Theoretical model of microsecond shockwave laser lithotripsy is developed. The destroying stone is considered to be a medium with low absorption and high scattering which contains high-absorptive organic inclusions. Laser radiation penetrates deep into such type of media and bulk destruction processes may occur in its significant volume. The distribution of energy fluence in stone volume was found in diffusion approximation. The evolution of state for each individual inclusion was studied. It was shown that the organic matter thermochemical decomposition plays an important role here. Such process leads to gas and high-absorption pyrocarbon generation. It produces sharp increasing of pore volume, cracks formation, and results shockwave generation. These processes change the state of illuminated stone layer-- lead to the formation of highly absorptive loose composition. Such layer change-- predestruction--produces conditions for the later effective transformation of laser energy. Some important dependencies for such processes were found both in simplified analytical form and numerically. Computer simulation for described model of microsecond laser lithotripsy was done with the parameters typical for ruby microsecond laser. Obtained results give the basis for the estimation of lithotripsy efficiency.

For the last two years we have applied continuous dual-wavelength Nd:YAG 20 - 60 W power laser to various urologic operations. Transmission of laser irradiation via a flexible quartz fiber permitted operating at any depth of the wound. High-intensity irradiation of 1.06 mkm wavelength was effective in making thin incisions into a variety of tissues, including skin, subcutaneous fat, aponeurosis, muscles, urinary bladder wall, prostate gland, renal pelvis, renal capsule and parenchyma, and urethra. The incisions were especially effective if the contact method was used. Operational access was accomplished in 3 - 5 minutes. At the same time, hemostasis occurred in small diameter vessels. More reliable hemostasis could be achieved by means of 1.32 mkm wavelength. With the present laser device, we carried out 57 different urologic operations in our clinic. Examples of such operations include prostatectomy, pyelolithotomy, ureterolithotomy, nephrectomy, resection of renal cysts, condylomata acuminata of the urogenital organs, and papilloma of the urethra and bladder. The results suggest that a combination of these two wavelengths may prove most effective. Advantages of this approach include a decreased blood loss and decreased surgical time, asepsis, good short- and long-term results, and no complications.

A ruby laser with a 0.694 mkm wavelength was used as a source of a new model of laser lithotriptor. The optical irradiation parameters selected included 1 mks duration pulse, frequency from 1 to 5 Hz, energy at an output of up to 120 mJ, transmitted via light guide quartz fiber of 400 kmk. The tip of the light guide was directed to the calculus through a catheterized cystoscope. Light guide position control was done by the presence of a specific acoustic signal accompanying plasma formation. Plasma is not formed by laser action on the ureter wall. In doubtful cases we used roentgenological examination. After lithotripsy and direct processing by irradiation, histological investigations of the ureter wall showed only slight submucosal hemorrhage or revealed no changes. Implantation of the calculus and fiber particles into the ureter wall was not observed. Twenty-nine patients were subjected to lithotripsy of calculus (oxalates, urates, phosphates) in the low and mid-ureter. Usually from 1000 to 3000 impulses were used to destroy the calculus. Calculus fragments passed without assistance (13 patients) or were removed by extractors (7 patients). The recovery of passing of urine and removal of renal colic were observed during lithotripsy if obturation had occurred (8 patients). Ureteral perforation, blood loss, and acute pyelonephritis did not occur.

18 cases of BHP were treated since 1990 by Nd:YALO₃ (Nd:YAP) laser transurethral prostatectomy. The ages of these patients from 54 to 88 years with a mean age of 69.6 years. In all cases, there were dysuria, 10 cases acute retention of urine, 5 cases residual urine more than 50 ml, 12 cases abnormal ECG. 4 cases chronic bronchitis and pulmonary emphysema, 4 cases hypertension and 3 cases diabetic. The working conditions of the laser machine are as follows: wavelength of laser: 1079.5 nm; output power of fiber: variation range from 0 to 100 w. The merits of the procedure were less bleeding during operation, shorter operation time and more quick convascence. Cure has been achieved in 11 cases and improvement in 2 cases. The indication, merits and complication of TULP were discussed.

A total of 21 consecutive patients with retention of urine underwent visual laser ablation of prostate. Twelve of these had spinal anesthesia, eight had local anesthesia and one had general anesthesia. Seventeen had acute retention; 13 from BPH, 1 due to carcinoma of prostate and three were due to Bladder Neck Stenosis (BNS). Four had chronic retention; three due to BPH and one due to BNS. A Nd:YAG/KTP laser was used and the laser was delivered via Angle Delivery Device. All 13 patients in acute retention due to BPH became catheter free after a mean catheter time of 8 days (range 1 - 22 days), the three patients with acute retention due to BNS were catheter free the next day after the laser incision of the BNS and the patient with acute retention from carcinoma of prostate required a TURP after 45 days of initial laser irradiation. Of the four patients with chronic retention, three with BPH required a TURP procedure after waiting over a month. The patient with chronic retention with BNS was catheter free after 7 days of his laser procedure. We conclude that laser prostatectomy using a side firing laser probe is effective in patients with acute retention but did not work well in our hands for chronic retention patients.

The fragmentation response of urinary and ureteral calculi via a single flexible UV quartz/quartz fiber with 320 micrometers core diameter has been studied in-vitro using a Q- switched solid-sate alexandrite laser system running simultaneously at two wavelengths in the Blue (380 nm) and Near-IR (760 nm) spectral region with continuously adjustable pulse energy ratios of both laser radiations. It was found that the fragmentation quality--compared to a dye laser system with 1.2 microsecond(s) ec pulse duration at 504 nm--is significantly better and faster, and strongly depends on the stone surface color, the acoustic impedance of the exterior/interior stone structure and the energy ratio of the Blue and Near-IR laser beams.