Visual laser ablation of the prostate: clinical experience in 108 patients

Use of Laser Technologies in Oncourology

Due to the increasing use of laser technologies in oncourology,we consider it relevant to publish a review of domesticand foreign articles for 2015-2021. The range of application ofvarious lasers in oncourology is very wide (holmium (Ho): YAG,thulium (Tm): YAG, etc.). In comparison with traditional surgicalinterventions, the greatest effectiveness of laser technologies incombination with endoscopy is clearly traced, the risks of intra –and postoperative complications are minimized, the period ofinpatient stay for patients changes.

Lasers in the surgical treatment of canine prostatic neoplasia and selected tumours of the male reproductive system

Light-based technologies are applied in various fields of medicine: for example optical diagnostics, light-activated therapy and surgery. Although light-based surgical procedures had hardly been a novelty, the revolutionizing moment for surgery came with the first use of light to cut tissue. Nowadays, surgical lasers are routinely used across numerous medical specialties, including gynaecology and urology. They are a part of the surgical treatment of benign prostatic hyperplasia, prostate carcinoma, penis carcinoma, genital skin lesions and orchidectomy. While in human urology lasers continue to establish their position as one of the standard surgical tools, veterinary patients are rarely treated with what here is still considered a technical innovation. However, through research on laser treatment of the prostate hyperplasia conducted on a canine model, veterinary medicine has gained a massive portion of data. It may prove beneficial for our clinical patients. In this review, we introduce the very principles of laser surgery as well as its current and future applications in oncologic surgery of the canine prostate gland and the male reproductive system.

Laser Application in Iran Urology: A Narrative Review

The usage of laser in medicine is not recent, and its history in urology goes back to 40 years ago. For the last 2 decades, common uses of laser have been treatments of subjects with urolithiasis, bladder tumors, benign prostatic enlargement, lesions of the genitalia and urinary tract strictures. To evaluate laser application in urology in Iran, we reviewed all of the Iranian literature on the topic. This study was designed to retrieve all studies on laser application in urology in Iran, regardless of publication status or language, covering years 1990-2017. Twenty-six articles were identified: 12 about urolithiasis, 8 about benign prostatic hyperplasia (BPH), 2 case reports, 1 paper about prostate cancer, 1 on female urethral stricture, 1 review and 1 basic sciences study. We conclude that the use of this technology has not yet found its position in Iran, especially in the field of urology. The main causes for it are the difficult accessibility and disturb of laser devices and its accessories, as well as the lack of adequate knowledge of the medical community about this modality.

Radial-firing optical fiber tip containing conical-shaped air-pocket for biomedical applications

We report a novel radial-firing optical fiber tip containing a conical-shaped air-pocket fabricated by deforming a hollow optical fiber using electric arc-discharge process. The hollow optical fiber was fusion spliced with a conventional optical fiber, simultaneously deforming into the intagliated conical-shaped region along the longitudinal fiber-axis of the fiber due to the gradual collapse of the cavity of the hollow optical fiber. Then the distal-end of the hollow optical fiber was sealed by the additional arc-discharge in order to obstruct the inflow of an external bio-substance or liquid to the inner air surface during the surgical operations, resulting in the formation of encased air-pocket in the silica glass fiber. Due to the total internal reflection of the laser beam at the conical-shaped air surface, the laser beam (λ = 632.8 nm) was deflected to the circumferential direction up to 87 degree with respect to the fiber-axis.

Best laser for prostatectomy in the year 2013

Lasers have come a long way in the management of benign prostatic hyperplasia. Over last nearly two decades, various different lasers have been utilized for prostatectomy. Neodymium: yttrium-aluminum-garnet laser that started this journey, is no longer used for prostatectomy. Holmium laser can achieve transurethral enucleation of the prostatic adenoma producing a fossa that can be compared with the fossa after Freyer's prostatectomy. Green light laser has a short learning curve, is nearly blood-less with good immediate results. Thulium laser is a faster cutting laser while diode laser is a portable laser device. Often laser prostatectomy is considered as a replacement for the standard transurethral resection of prostate (TURP). To be comparable, laser should reduce or avoid the immediate and long-term complications of TURP, especially bleeding and need for blood transfusion. It should also be safe in the ever increasing patient population on antiplatelet and anticoagulant drugs. We need to take stock of the situation and identify, which among the present day lasers has stood the test of time. A review of the literature was performed to see if any of these lasers could be called the “best laser for prostatectomy in 2013.”

The evolution of lasers in urology

The world's first laser was developed by Theodore Maiman in 1960. Over the course of the past five decades, this technology has evolved into a highly specialized entity, also finding a niche market in the field of urology. Lasers obtained from various lasing mediums producing amplified light of different wavelengths have been tested for urological applications. Today, these lasers are most commonly used in the surgical management of benign prostatic hyperplasia and as intracorporeal lithotripters. Other uses include ablation of various urologic tumors and incising strictures of the upper- and lower urinary tract. A continuous process of evolution of this technology is taking place, resulting in surgical lasers becoming ever safer, more effective, and more affordable.

Laser treatment of symptomatic benign prostatic hyperplasia

The treatment of lower urinary symptoms secondary to benign prostatic hyperplasia (BPH) after failure of medical therapies remains controversial for most urologic surgeons. The complications of traditional surgery are the driving force behind the development of several minimally invasive treatments of symptomatic BPH. Laser prostatectomy is one of the most investigated such modalities. In this article we reviewed the results of the most common types of lasers used in prostatic surgery.

A randomized prospective study of laser ablation of the prostate versus transurethral resection of the prostate in men with benign prostatic hyperplasia

OBJECTIVES

To compare the safety and efficacy of laser ablation of the prostate, one of the minimally invasive treatments available for men with benign prostatic hyperplasia, to transurethral resection of the prostate (TURP).

METHODS

A prospective randomized study of 100 men with benign prostatic hyperplasia, with 50 patients in each treatment arm, was conducted. All patients met the entry criteria: age older than 45 years, no history of carcinoma of the prostate, a peak flow rate less than 15 mL/s, medical therapy failure, and the ability to undergo regional or general anesthesia. All patients underwent a preoperative evaluation consisting of the American Urological Association (AUA) symptom score, uroflowmetry, pressure-flow study, transrectal ultrasound for prostate volume, and serum prostate-specific antigen determination. Patients underwent either TURP or laser ablation of the prostate using the potassium titanyl phosphate (KTP)/neodymium: yttrium-aluminum-garnet laser. Patients were seen for follow-up at 1, 3, 6, and 12 months.

RESULTS

The mean age was 68.2 years (range 45 to 90) for the laser group and 67.4 years (range 54 to 82) for the TURP group. The mean AUA symptom score was 22 for the laser group and 21 for the TURP group. The mean peak uroflow rate was 7.6 +/- 3.4 mL/s for the laser group and 6.5 +/- 4.0 mL/s for the TURP group. At 12 months of follow-up, the mean AUA symptom score had decreased to 7 (-69.5%) for the laser group and to 3 (-80.9%) for the TURP group. The mean peak uroflow rate increased to 15.4 mL/s (+ 107.8%) for the laser group and to 16.7 mL/s (+ 150.7%) for the TURP cohort. Seventy-five percent of the laser group had a 50% or greater decrease in their individual AUA symptom score compared with 93% of the TURP group. Sixty-five percent of the laser cohort had a 50% or greater increase in their peak uroflow rate compared with 75% of the TURP cohort.

CONCLUSIONS

Laser prostatectomy produced improvements in the peak flow rate and symptom score similar to those produced by TURP. The patients who underwent laser treatment required a longer period to reach maximum improvement, which probably reflects the lack of tissue debulking at the time of surgery. Further improvement in laser technology will be required to produce more immediate results.

Hybrid laser treatment compared with transurethral resection of the prostate for symptomatic bladder outlet obstruction caused by a large benign prostate: a prospective, randomized trial with a 6-month follow-up

OBJECTIVE

To compare the efficacy and safety of hybrid laser treatment, i.e. the combination of visual Nd-YAG laser ablation of prostate and contact Nd-YAG laser vaporization of prostate, with transurethral resection of the prostate (TURP) in the treatment of patients with symptomatic bladder outlet obstruction secondary to a benign high-volume prostate.

PATIENTS AND METHODS

Forty-five symptomatic patients with hyperplastic prostates of >40 mL were randomized to undergo either hybrid laser treatment (21) or TURP (24). All patients were evaluated before and after treatment with a complex urodynamic assessment, and were accepted into the study only if they had infravesical obstruction in the pressure-flow study. In the hybrid method, Nd-YAG laser energy was first delivered by an 'adenoma-dependent' approach to all areas of the obstructing lateral lobe tissue through a side-firing gold-alloy tip fibre at 40 W for 90 s of 'burn'. The prostatic urethra was then opened and the median lobe vaporized using the a contact probe at 40 W. Patients were re-evaluated 3 and 6 months after treatment.

RESULTS

Both treatments proved to be safe, and improved the subjective and objective outcome measures at 3 and 6 months compared with baseline values. After 3 months, there was a greater improvement in the TURP group in peak urinary flow rate (Qmax; P<0.01), mean urinary flow rate (Qave; P<0.01) and postvoid residual urine volume (P<0.05) than in the hybrid laser group. After 6 months, there was a greater improvement in the TURP group in detrusor pressure at Qmax (P<0.01), Qave (P<0.05) and prostate size (P<0.001) than in the hybrid laser group. In the pressure-flow study at 6 months, a higher proportion of patients (seven of 19) were still obstructed in the hybrid laser group than in TURP group (two of 21; P<0.05). TURP caused more intraoperative blood loss (P<0.001) and postoperative problems associated with bleeding; 38% of hybrid laser patients were discharged with a suprapubic catheter, whereas all TURP patients could urinate at discharge (P<0.01). The duration of bladder drainage was longer after hybrid laser treatment (P<0.001).

CONCLUSION

The hybrid laser method was a safe but less effective treatment than TURP for benign prostatic enlargement in patients with prostates of >40 mL.

The follow-up of patients with unfavourable early results of transurethral prostatectomy

OBJECTIVE

To determine the natural course of patients with subjectively disappointing early results after transurethral prostatectomy (TURP), who experience prolonged discomfort and an initial deterioration in symptoms.

PATIENTS AND METHODS

A consecutive series of 127 patients undergoing urodynamic studies and TURP were assessed 3 months after surgery using symptom scores and measurements of urinary flow rate; 107 patients reported improved symptom and quality-of-life scores, but 20 did not improve, with no change or a deterioration. These 20 patients were followed for several months using symptom scores, and measurements of flow rates and residual urine volumes. Baseline variables, including preoperative urodynamic studies, were compared between those who improved and those who did not.

RESULTS

Over a mean (range) follow-up of 10.6 (6-15) months, all those initially not improving showed spontaneous improvement in all three variables with no further treatment and eventually achieved the same significant degree of improvement as those who improved soon after TURP. Preoperatively, those initially not improving had mean lower symptom scores, more bladder irritability and less obstruction than did those who improved.

CONCLUSION

A significant proportion (approximately 15%) of patients with obstructive symptoms will experience considerable symptomatic discomfort for a prolonged period after an uncomplicated TURP and will not gain the full symptomatic benefit from the procedure until 6-9 months afterward.

Simplified treatment planning for interstitial laser thermotherapy by disregarding light transport: a numerical study

BACKGROUND AND OBJECTIVE

The objective was to investigate the effect of light transport on the temperature distribution and the coagulated volume under conditions relevant to interstitial laser thermotherapy (ILT) of tumors in the human liver.

STUDY DESIGN/MATERIALS AND METHODS

Temperature distributions and coagulated volumes produced with a diffusing laser fiber or a conductive heat source, at equal output power, were numerically calculated for tissue with different optical penetration depths. Four irradiation times (5, 10, 20, and 30 min) were studied. A three-dimensional finite-element model was used to calculate the temperature distribution during heating with four conductive heat sources (no light emission). Results were compared with measured temperature distributions during laser irradiation in a gel phantom with known optical properties.

RESULTS

Numerical calculations showed that the influence of light transport on the coagulated volume was negligible in tissue with optical penetration depths below 3-4 mm at all studied irradiation times. The phantom experiment indicated good agreement with the calculated temperature distribution, both with a single diffusing laser fiber and with four fibers.

CONCLUSION

Light transport influences coagulated volumes only slightly under conditions presented in this work, which is relevant to ILT of tumors in the human liver.

A prospective randomized controlled trial of hybrid laser treatment or transurethral resection of the prostate, with a 1-year follow-up

OBJECTIVE

To compare the clinical outcome after hybrid laser treatment of the prostate, combining potassium titanyl phosphate (KTP) and Nd:YAG lasers, with transurethral resection of the prostate (TURP).

PATIENTS AND METHODS

A prospective randomized trial was conducted to compare laser treatment and TURP. The hybrid laser treatment technique involved performing initial 30 W KTP vaporizing bladder neck incisions and prostatotomies followed by a 'free-paint' application of 60 W Nd:YAG coagulation energy. Patients were re-assessed after 6 weeks, 6 months and 1 year, using the International Prostate Symptom Score (IPSS) and uroflowmetry. TURP was conducted using conventional methods.

RESULTS

In all, 204 patients were randomized into the study; at 6 weeks there were significant differences between the groups for the IPSS (12.4 vs 9.1, P=0.001) and maximum urinary flow rates (16.1 vs 20.8 mL/S, P<0. 001) in favour of the TURP group. At 6 months and one year this difference had disappeared. Similar numbers of patients in each group complained of bothersome postoperative urinary symptoms (23% vs 19%). Blood transfusions (5% vs none) and urethral strictures (9% vs 2%) were more common after TURP, whereas more early infective complications occurred after hybrid laser treatment (24% vs 5%). Only one patient in each group required re-operation because of poor resolution of symptoms.

CONCLUSIONS

At one year, hybrid KTP/Nd:YAG laser treatment of the prostate was equivalent to TURP in the improvements in IPSS, maximum urinary flow rate and post-void residual urine.

Urolase v ultraline fibers in laser prostatectomy: 3-year follow-up of a randomized study

Recently, laser treatment of the prostate has been added to the urologist's armamentarium for the treatment of bladder outlet obstruction secondary to benign prostatic hyperplasia (BPH). Until now, limited data on long-term outcome are available notwithstanding the fact that such information is crucial in determining the ultimate role of laser prostatectomy in the treatment of BPH. We now have 3-year data of a comparative study using the Urolase and Ultraline fiber in Nd:YAG sidefiring laser prostatectomy. The study was performed to compare laser prostatectomy using a pure coagulation (Urolase fiber) and a combination of a coagulation and vaporization (Ultraline fiber). In a period of 15 months, 93 men were randomized for laser treatment with the Ultraline fiber (N = 44) or the Urolase fiber (N = 49). Symptom scores, maximal uroflow, postvoiding residual volume, and sexual history were noted over a 3-year period. Adverse events and retreatments were also recorded. The mean postoperative catheterization time was 18 days, without significant difference between the two groups. After 3 years, we demonstrated a durable improvement in maximal flow rate, from 7.8 to 13.9 mL/sec in the Urolase group and from 7.9 to 13.6 mL/sec in the Ultraline group. In both groups, however, a considerable decrease in the maximal flow rate was noted after 3 years compared with 3 months after treatment, from 18.7 to 13.9 mL/sec in the Urolase group and from 20.0 to 13.6 mL/sec in the Ultraline group. The symptom scores showed marked and lasting improvement. The postvoiding residual urine volume became very low in the early postoperative period but did significantly increase after 3 years; nevertheless, it was still only 50% of the preoperative value. Although after 3 years, the maximal uroflow rate was still significantly improved compared with baseline, a considerable decrease was noted when compared with the early postoperative value. The same considerable and lasting improvement in subjective outcome (symptom scores) was seen in both groups. Although the Ultraline fiber also causes vaporization of prostatic tissue, no differences could be noted in the clinical outcome obtained with the two fibers.

Transurethral prostate ablation using saline-liquid electrode introduced via flexible cystoscope

An interstitial saline-electrode has been developed to couple radiofrequency (RF) energy to prostate tissue in order to produce large lesions quickly and controllably. In this study, we attempted to produce similar results using a flexible catheter introduced transurethrally via a flexible cystoscope. An insulated 4F catheter with an extendable needle electrode (26-gauge, 5-mm exposed metal tip) was introduced through a port of a flexible cystoscope into the urethra of 10 dogs via a small perineal incision (required for the canine U-shaped urethra). Under visual endoscopic guidance, the electrode was placed in the center of the prostate and the needle electrode extended at an angle into the prostate, one lobe at a time. Hypertonic saline (14.6% NaCl) was infused at 2 mL/min through the needle electrode into the tissue for 30 seconds before and during RF application. The energy (50 W, 475 kHz) was delivered for 30, 45, 60, or 90 seconds (RFT System; U.S. Surgical Corporation). Prostate and urethral temperatures were monitored using thermocouples mounted on the catheter. There was an automatic high-temperature shut-off if the urethra reached >42 degrees C or if impedance reached >300 omega during RF energy application. Prostate sizes ranged from 1.4 x 2.0 x 1.4 cm to 5.0 x 4.5 x 4.2 cm. In this group, there were no automatic shut-offs at any of the energy durations, and the lesions produced ranged from 1.3 x 1.3 x 1.1 cm (0.99 cm3) to 1.6 x 2.7 x 2.2 cm (5.03 cm3). The average ablation volumes produced were 1.76 cm3 at 30 seconds' RF application, 2.42 cm3 at 45 seconds, 3.96 cm3 at 60 seconds, and 5.03 cm3 at 90 seconds. Histologic examination revealed typical coagulation necrosis in the treatment zone without tissue desiccation. Introduction of the saline-electrode through a flexible cystoscope provides a minimally invasive procedure that quickly and controllably produces large lesions that may provide effective treatment for benign prostatic hyperplasia with less patient discomfort.

Why is transurethral microwave thermotherapy (TUMT) positively effective?

Between 1992 and 1994, 157 patients with benign prostatic hyperplasia were treated with transurethral microwave thermotherapy (TUMT). In evaluating the efficacy of TUMT with the International PrOstate Symptom Score (I-PSS) in 121 patients, 18 (15%) showed excellent and 42 (35%) showed good response. In evaluation of QOL, the result was 43 patients (33%) excellent and 42 patients (35%) good response. In objective evaluation of uroflow in 93 patients, 12 (13%) showed excellent and 13 (14%) showed good response. The prostatic volume did not show a significant decrease after treatment. In terms of overall improvement, according to the criteria proposed at the 2nd International Consultation on BPH, the treatment was considered effective in 53 of 108 patients (48%). Histological examination of the prostate enucleated from a patient 7 months after TUMT revealed degenerative changes of nerve fibres on S-100 protein immunohistochemical staining, which were more extensive than those in smooth muscle cells on HE staining. In in vitro tests the isometric contraction force of the rabbit prostatic tissue was measured after exposure to different temperatures, ranging from 37 to 50 degrees C. No significant change was observed up to 45 degrees C vs. 37 degrees C. After exposure to 48 degrees C, the nerve mediated contractions became completely depressed, although phenylephrine or KCl induced contractions were only partially suppressed. After exposure to 50 degrees C, no contraction was induced by any type of stimuli. In conclusion, it is suggested that good symptomatic improvement after TUMT results from both neural and muscular damage to the prostate. As TUMT is not aiming at a relief of anatomical obstruction, 50 degrees C is thought to be a sufficient thermal condition to cause an irreversible damage to prostatic tissue, which will provide a relief from functional obstruction and urethral instability.

High-power potassium titanyl phosphate laser vaporization prostatectomy

In a search for potential therapeutic strategies for benign prostatic hyperplasia (BPH) that would be associated with less morbidity than transurethral resection of the prostate, various types of laser prostatectomy have been used. Although the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser allows performance of prostatectomy in an almost bloodless field and without absorption of irrigant, the remaining necrotic tissue causes bladder outlet obstruction and related symptoms for 5 to 7 days after treatment. In contrast, the potassium titanyl phosphate (KTP) laser has been found to vaporize tissue with minimal coagulation of the underlying structures. With use of the KTP laser, heat is concentrated into a small volume, the tissue is ablated by rapid vaporization of cellular water, and a 2-mm rim of coagulated tissue is left. After favorable results were obtained in studies of canine prostates and human cadavers, we implemented clinical use of 60-W KTP laser prostatectomy in selected patients. In 10 patients with symptomatic BPH who ranged in age from 52 to 80 years, outpatient KTP laser prostatectomy yielded significantly increased mean peak urinary flow rates (from 8.0 mL/s preoperatively to 19.4 mL/s within 24 hours after the procedure). No patient had hematuria, dysuria, or incontinence after removal of the catheter, and no patient required recatheterization. One patient, however, had urgency, and two other patients became febrile during the 24-hour observation period. Overall, KTP laser vaporization prostatectomy can provide immediate relief from obstructive symptoms of BPH and is not associated with dysuria.

Catheter-free endoscopic laser ablation of the prostate using a 1-size prostatic stent

PURPOSE

Endoscopic laser ablation of the prostate is a safe alternative to transurethral prostatic resection. Recognized disadvantages include prolonged catheterization, postoperative discomfort and delayed symptomatic improvement. We assessed the role of a 1-size temporary prostatic stent in men undergoing endoscopic laser ablation of the prostate.

MATERIALS AND METHODS

A total of 55 men a mean of 73 years old with outflow obstruction, including 9 who presented in urinary retention, underwent endoscopic laser ablation of the prostate and temporary stenting. Urinary flow rate, residual urine volume, symptom score and prostate specific antigen were measured preoperatively, and 6 weeks (with the stent in situ), 3 months (after stent removal) and 12 months postoperatively. Duration of hospital stay and complications were also recorded.

RESULTS

Of the 55 men 37 (67%) voided immediately with the stent in situ, including 7 of the 9 in retention. At 6 weeks with the stent in place mean maximum urine flow was 17.3 ml. per second (preoperatively 8.7). Dysuria was reported by 3 patients. Stent related complications were rare. One stent migrated early, resulting in urinary retention, while 2 that migrated late were asymptomatic. No patient had acute urinary retention after stent removal. Maximum urinary flow rate measured at 6 weeks with the stent in situ was similar to that 1 year after endoscopic laser ablation of the prostate.

CONCLUSIONS

The use of a 1-size, inexpensive plastic prostatic stent enabled catheter-free endoscopic laser ablation of the prostate in 67% of our patients. Early improvements in the urinary flow rate and a lower incidence of dysuria were additional benefits. The result of endoscopic laser ablation of the prostate at 1 year was comparable to that of transurethral prostatic resection.

Influence of decay of laser fibers during laser prostatectomy on clinical results

Three types of sidefiring laser fibers (34 Urolase, 20 Ultraline, and 114 Prolase II) were visually inspected after a laser prostatectomy, and transmission measurements were performed using a power meter (Aquarius). The results were correlated with the clinical outcome. Despite differences in the amount of loss in transmission for the fibers used, we could not establish any significant effect on clinical outcome measures, such as improvement in maximal flow rate or symptom score. The visual aspect of the Urolase fibers was significantly related to the amount of transmission loss, whereas no such relation was found for the other two types of fibers. Prostate size and the total amount of energy delivered by the laser source also did not correlate with the clinical outcome. To determine the relation between the energy absorbed by the prostate and clinical outcome, a large number of patients must be evaluated, and any factor that can be controlled needs to be monitored. For the latter, the power meter as presented here is a useful complementary tool.

The American Urological Association Symptom Index: early postoperative evaluation of irritative and obstructive symptoms due to benign prostatic hyperplasia

In order to evaluate the acute effects of two different treatments on changes in the American Urological Association symptom score, we divided 23 men with benign prostatic hyperplasia into 2 groups. Group 1 (n = 16) and group 2 (n = 7) were treated with transurethral resection of the prostate and visual laser ablation of the prostate, respectively. Twice before and about 1 week after surgery, patients completed the AUA symptom questionnaire and underwent urodynamic evaluation. The symptom indexes were subcategorized as obstructive and irritative symptoms. All symptom scores were identical in groups 1 and 2 preoperatively. Postoperatively, significant improvement was found in obstructive scores, the total score, maximum and average flow rates only in group 1. This outcome is probably the reflection of an essential dissmilarity in both therapies. Clinically, the obstructive subscore appears reactive to changes in obstruction and seems meaningful in follow-up even in the early postoperative days.

Transurethral prostate ablation with saline electrode allows controlled production of larger lesions than conventional methods

A novel technique for prostate ablation using radiofrequency (RF) energy coupled to tissue with interstitial perfusion of saline solutions from a screw-tip catheter has been developed. The electrolyte spreads the current density away from the metal electrode and increases the effective electrode surface area, allowing more RF power input. This prevents tissue desiccation and impedance rise, resulting in controlled production of large lesions. In this study, we attempted to produce similar results using a straight needle and the saline electrode with a transurethral approach and compared the results with those of the same technique without electrolyte perfusion (conventional RF method). For this study, we designed an insulated 22-gauge needle with thermocouples embedded along its length and a 1-cm exposed tip with a retractable intraluminal thermocouple. This needle was inserted into the urethra of 10 dogs through a small perineal incision. Under transrectal ultrasound guidance, the exposed tip of the needle was placed in the center of each lobe. The intraluminal thermocouple was moved from the exposed tip up to the prostate capsule to monitor temperature. The highest power that could be applied in conventional RF methods without immediate desiccation was determined from preliminary experiments as 10 W. Subsequently, 10 W of RF power (475 kHZ) was delivered in one lobe until either the capsule temperature reached 48 degrees C or high impedance (> 400 omega) occurred. In the other lobe, 50 W of RF energy (475 kHz) and electrolyte perfusion (14.6% NaCl, 1 mL/min) were delivered until the capsule temperature reached 48 degrees C or high impedance occurred. Prostate lobe sizes ranged from 3.93 cm3 to 44.47 cm3 (mean 15.07 cm3). At 10 W without saline perfusion, high impedance from tissue desiccation occurred at 45 +/- 27 seconds, with lesions ranging from 0.06 cm3 to 0.93 cm3 (mean 0.34 cm3). At 50 W with saline perfusion, there was no tissue desiccation or impedance rise. The RF application time averaged 181 +/- 115 seconds until the capsule reached 48 degrees C, resulting in lesions ranging from 2.53 cm3 to 22.88 cm3 (mean 8.54 cm3). This study demonstrates that transurethral ablation of the prostate with a saline electrode allows controlled production of larger lesions than conventional RF methods. This may permit a single RF application in each lobe to produce lesions effective for the treatment of benign prostatic hyperplasia even in large glands.

Visual laser ablation of the prostate (VLAP) with bare fiber in conjunction with laser bladder neck incision in the treatment of patients with benign prostatic hyperplasia (BPH)

The objective of this paper was to assess the effectiveness of visual laser ablation of the prostate (VLAP) using a bare fiber with simultaneous laser incision of the bladder neck for patients with symptomatic benign prostatic hyperplasia. Sixty-seven patients with symptomatic bladder outlet obstruction due to benign prostatic hyperplasia were entered into a prospective trial where VLAP was done with neodymium:YAG laser, while the bladder neck incision was done with KTP laser. The laser was delivered using a bare fiber. There was marked improvement demonstrated at three months post-lasing in symptom score and flow rate. No significant changes were noticed in the subsequent follow-up. However, the addition of the bladder neck incision increased the rate of retrograde ejaculation without appreciable improvement in symptom score or flow rate when compared to other published data. None of the patients developed bladder neck contracture. VLAP, using a bare fiber, in conjunction with laser bladder neck incision, produces durable improvement in urine flow rate and symptom score in patients with symptomatic benign prostatic hyperplasia without the development of bladder neck contracture. This method will reduce the costs of laser prostatectomy.

Histomorphological changes after neodymium: YAG laser-coagulation of the human prostate with the Side Focus fiber. Effect of power setting and time

The objective of our study was to determine optimal treatment parameters and appropriate methods of examination for neodymium:yttrium-aluminum-garnet (Nd:YAG) high-power laser coagulation of the human prostate in relation to power setting and time. Transurethral free-beam laser coagulation was performed with the Side Focus side-firing laser fiber in ten patients prior to planned radical surgery, of whom six underwent transperitoneal laparoscopic lymphadenectomy and laser coagulation 4-9 days prior to open surgery. Depth and volume of coagulated prostatic tissue were measured at power setting/time combinations of 40 W/90 s and 60 W/60 s, respectively, while holding total energy delivery constant. Microscopic examination in the early phase showed that epithelial cells had become loose from the basal-cell membrane. By 4-9 days there was evidence of conspicuous squamous epithelial metaplasia with a high proliferation rate as a sign of re-epithelialization. Using the Side Focus side-firing laser fiber, both treatment modalities showed comparable volume coagulation. In contrast there was a significant difference between those prostates removed at 4-9 days and those removed at 60-210 min after laser coagulation. We conclude that laser-induced changes in the human prostate are conclusively discernible only after 4 days.

Transurethral electrovaporization of the prostate: one-year experience

OBJECTIVES

To determine the safety and efficacy of transurethral electrovaporization of the prostate (TVP) in men with lower urinary tract symptoms.

METHODS

A prospective trial of 114 consecutive patients who underwent TVP since August 1994 was conducted. The mean follow-up period was 12.3 months. Parameters evaluated included American Urological Association symptom score (Sx), peak urinary flow rate (Qmax), operative time, postoperative catheterization time, length of hospital stay, and loss of days from work.

RESULTS

Of the 109 men available for follow-up, Sx decreased from 16.7 to 7.3, 6.5, 6.3, and 5.4 at 3, 6, 12, and 18 months, respectively (P < 0.001), whereas Qmax increased from 7.9 to 14.8, 15.6, 16.7, and 16.5 mL/s at 3, 6, 12, and 18 months, respectively (P < 0.001). Mean catheterization time was 10.4 hours; mean hospital period was 0.9 days, and average loss of days from work was 5.6. Complications included intermittent postoperative hematuria in 65 patients (57%). Clot retention in 6 (5%), and bulbar urethral stricture in 2 (2%). Of 74 men who were potent preoperatively, none had postoperative erectile dysfunction; retrograde ejaculation was noted in 62 (84%). Significant postoperative irritative symptoms were reported in 10 men (9%).

CONCLUSIONS

On the basis of 1-year follow-up data, this study demonstrates that TVP is a safe and effective modality for treating lower urinary tract symptoms. However, longer, prospective, blinded studies are needed to determine efficacy relative to transurethral resection of the prostate.

Holmium:YAG laser prostatectomy: results of U.S. pilot study

The holmium:YAG (Ho:YAG) laser wavelength's ability to vaporize and incise soft tissue offers potential advantages for prostatectomy compared with the Nd:YAG laser, which primarily produces tissue coagulation. In this initial U.S. trial, Ho:YAG laser prostatectomy was performed in 20 men, including 2 men treated immediately prior to radical prostatectomy to assess Ho:YAG laser tissue effects in the prostate. A total of 18 men were treated for clinically symptomatic bladder outlet obstruction secondary to benign prostatic hyperplasia (BPH). Estimated excess BPH tissue averaged 24 g (range 5-50 g). A mean of 129 kJ of Ho:YAG laser energy was delivered, combined with a mean of 11 kJ of Nd:YAG energy to provide supplemental coagulation for hemostasis. The mean operative time was 1 hour 34 minutes. No significant intraoperative changes in hematocrit or serum electrolytes were documented. No perioperative or late complications occurred. The mean postoperative catheterization time was 1.4 days. Of the 18 patients, 16 (90%) underwent a successful voiding trial on the first postoperative morning. Immediate improvement in voiding, comparable to that seen after transurethral electrocautery resection of the prostate (TURP), was reported by all patients. Ho:YAG laser resection of the prostate appears to be a useful surgical technique associated with minimal morbidity and immediate improvement in voiding.

Laser treatment of the prostate using the Urolase fiber: the Dutch experience

PURPOSE

Subjective and objective results were assessed after laser prostatectomy with the Urolase fiber at 5 different centers in The Netherlands.

MATERIALS AND METHODS

Patients were evaluated with the international prostatic symptom score questionnaire, uroflowmetry and post-void residual volume measurements. Urodynamic investigations with pressure-flow analysis were performed at 2 centers.

RESULTS

Data for 233 patients were evaluated. Overall significant improvement in mean international prostatic symptom score, maximum flow, post-void residual and urodynamic parameters was noted. Differences in outcome among the centers may be due to variation of technique or different selection criteria. Postoperative morbidity was significant, with irritative voiding complaints for 4 to 6 weeks in up to 50% of all patients and urinary tract infections in 21.1%.

CONCLUSIONS

Laser prostatectomy results in subjective and objective improvement, which is operator independent. Despite the observation that perioperative (intraoperative and immediate postoperative) morbidity seems less severe compared to transurethral resection of the prostate, there is a shift toward greater postoperative morbidity.

Laser prostatectomy: two and a half years' experience with aggressive multifocal therapy

OBJECTIVES

The aim of this study was to evaluate patient outcome 1 to 2 1/2 years after aggressive neodymium: yttrium-aluminum-garnet (Nd:YAG) laser prostatectomy alone or combined with potassium titanyl phosphate (KTP/532) laser therapy.

METHODS

In 32 men with symptomatic bladder outlet obstruction caused by benign prostatic hyperplasia, Nd:YAG laser energy (40 W) was delivered to six or more locations on the prostatic lateral lobes and one or more on the median lobe. In a subgroup of 15 of these patients, the prostate was also incised and sculpted with KTP/532 laser to create a better channel.

RESULTS

In the 32 men, voiding parameters improved: mean peak flow rate increased from 10 to 21 mL/s (110%), residual volume decreased from 167 to 64 mL (62%), and American Urological Association (AUA) symptom score decreased from 24 to 9 (63%). Catheters were removed after 3 days. Of the 17 patients treated with the Nd:YAG laser alone, 12 (70.5%) required recatheterization, whereas only 5 of the 15 (33%) who received KTP/532 laser therapy after Nd:YAG treatment required recatheterization (P < 0.001). In the entire group of 32 patients, complications included predictably prolonged retention (14 to 60 days) in 4 patients (12.5%) with hypotonic bladders, prolonged dysuria in 4 (12.5%), vesical neck contracture in 2 (6%), and significant hematuria in 1; none had incontinence. All 25 sexually active men remained potent (100%), but among these patients retrograde ejaculation developed in 5 (20%).

CONCLUSIONS

Aggressive Nd:YAG laser prostatectomy is safe and effective for obstructive prostates up to 70 mL in volume and produces good results that are sustained for up to 2 1/2 years. Adjunctive KTP/532 laser therapy apparently creates an unobstructed channel more quickly and reduces the rate of postoperative retention, but it does not alter other voiding parameters.

Theoretical analysis of transurethral laser-induced thermo-therapy for treatment of benign prostatic hyperplasia. Evaluation of a water-cooled applicator

A mathematical model for predicting the temperature rise in transurethral laser-induced thermo-therapy for benign prostatic hyperplasia was developed. In the model an optical line source emitting light from an Nd:YAG laser isotropically was placed in the urethra. Water cooling of the urethral epithelium was modelled using a two-tube system. The relationship between the difference in outlet and inlet water temperatures and the highest tissue temperature level reached was theoretically investigated. It was found that the water temperature difference was linearly dependent on the steady-state maximum tissue temperature. The theoretical calculations suggest that the water-cooled applicator can be used to measure the maximum tissue temperature. With temperature control, the prostatic tissue temperature can be prevented from exceeding the boiling point of water, excluding tissue carbonization. The model was also used to evaluate the influence of a number of different parameters on the damaged tissue volume. Increasing the urethral lumen radius by a factor of two by means of inserting different sized tubes was found to augment the tissue volume raised to therapeutic temperatures by up to 50%. The calculations showed that cooling of the urethral epithelium can result in an increase in the damaged volume by 80% as compared to not applying any cooling. The temperature of the cooling water was found to influence the tissue temperature only to a small extent.

A non-randomized comparative study of visual laser ablation and transurethral resection of the prostate in benign prostatic hyperplasia

BACKGROUND

Transurethral resection of the prostate (TURP) has been the preferred surgical treatment for benign prostatic hyperplasia (BPH) for the past 50 years. Alternative methods for treating BPH such as visual laser ablation (VLAP) have been established during the past decade. In order to assess the safety and efficacy of VLAP, this alternative method was performed using a Urolase fiber and neodymium: yttrium-aluminum-garnet laser, and compared to results obtained in patients treated with TURP for BPH.

METHODS

In this non-randomized comparative study, 100 BPH patients were equally split between treatment with VLAP or TURP, and their cases compared. The efficacy was assessed using an International Prostate Symptom Score, urinary flow rates, post-void residual urinary volume and an estimated prostate volume.

RESULTS

There was a clinically significant improvement in all parameters in both groups. In the VLAP and TURP groups, 92.0% and 81.6%, 90.2% and 86.2 and 93.1% and 100.0% were categorized as effectively-treated cases at 3, 6 and 12 months post-operatively, respectively. No severe side effect was seen in VLAP group. The total and post-operative lengths of hospitalization in the VLAP group were shorter, but the duration of post-operative bladder irrigation was longer in these patients.

CONCLUSIONS

Although TURP remains the standard surgical treatment for BPH, VLAP is associated with less morbidity and the clinical outcome is similar compared to patients treated with TURP. VLAP in conjunction with TURP may result in less risk of postoperative urinary retention and vesical irritability.

Prostatism: benign prostatic hyperplasia

This article is devoted to the most common cause of outlet obstruction in the male geriatric population, benign prostate hyperplasia (BPH). The prevalence, pathophysiology, and natural history of BPH is discussed, along with the work-up and indications for medical or surgical intervention. The authors also focus on medical and surgical options now available for management of BPH.

Enhanced radiofrequency ablation of canine prostate utilizing a liquid conductor: the virtual electrode

Conventional radiofrequency (RF) ablative techniques have shown promise for the treatment of symptomatic benign prostatic hyperplasia (BPH); however, present RF technology is limited by the small lesion size, necessitating several probe placements and heating cycles to achieve sizable lesions. This limitation is attributable primarily to a rapid increase in electrical impedance secondary to tissue desiccation and charring at the electrode tip. We devised a hollow screw-tip needle electrode that permits fixation to tissue, recording of temperature and impedance, infusion of fluid, and delivery of RF energy. Infusion of electrolyte solution (i.e., saline) into tissue prevents impedance rise by conducting RF energy away from the metal electrode and permits the creation of large lesions. By varying the conductivity of the perfusate (concentration and temperature), lesions of large diameter can be created in a controlled manner. To determine the long-term tissue effects, we applied this new modified RF technique to the prostates of five mongrel dogs in a chronic (0.5 to 8-week) study. The screw-tip electrode was serially embedded into each lobe of the perineally exposed glands with 1-minute infusion of 0.9% saline (2 mL/min) followed by application of RF energy (500 KHz, 50 W, 2-18 minutes) along with continuous saline infusion. Thermocouples were embedded 5 mm below and at the gland capsule, and RF application was discontinued when the temperature reached 50 degrees C at the periphery. Postoperatively, the animals were examined daily for clinical status and weekly for glandular changes using transrectal ultrasonography. At predetermined intervals, the animals were sacrificed and the prostates excised, measured, sectioned, and examined for histologic changes. Ablative tissue temperatures of 50 to 100 degrees C were produced while impedance remained stable. Four animals required a single catheterization for relief of urinary retention between days 2 and 3; otherwise, all animals demonstrated a quick and uneventful recovery with no edema detectable on day 7 ultrasound examination. The outside dimensions of the gland remained relatively constant throughout the study (+ or - 0.39 cm L + W + H). Histologic examination revealed coagulation necrosis (ablation) in both lobes of all prostates (69.94% + or - 16.62% of the gland) with tissueless cavities forming from the ablation area (28.71% + or - 8.24% of the gland) contained within the capsule surrounded by healthy tissue at the periphery. Intraprostatic lesions were obtained without any gross damage to surrounding tissue, including the bladder and rectal wall. Utilizing a liquid conductor in prostate tissue allows a single electrode-placement heating cycle for controlled ablation for the potential treatment of BPH. This new technique produces more extensive and uniform lesions than conventional RF procedures, and lesion size is limited only by the duration of RF energy application.

Holmium: YAG laser prostatectomy canine feasibility study

BACKGROUND AND OBJECTIVE

Laser coagulation prostatectomy performed with the Neodymium: Yttrium-Aluminum-Garnet laser has emerged as a viable alternative for the treatment of benign prostatic hyperplasia. Laser vaporization prostatectomy, if feasible, has the potential to reduce postoperative catheterization time and achievement time of maximum voiding outcomes. The objective of this study was to determine the ability of the Holmium: Yttrium-Aluminum-Garnet laser wavelength to vaporize prostatic tissue and create an immediate prostatectomy defect.

STUDY DESIGN/MATERIALS AND METHODS

The Holmium: Yttrium-Aluminum-Garnet laser was applied in vivo in a canine prostate model. Laser energy was delivered endoscopically via quartz laser fibers circumferentially to each prostatic fossa. High energies, up to 2.8 joules per pulse and 60 watts total power, were utilized. All prostates were surgically removed immediately following laser applications to determine acute laser effects.

RESULTS

Immediate tissue ablation or vaporization with this laser wavelength was found to be both feasible and relatively efficient. The mean transverse dimension of the prostatic defects produced was 19 mm, with a maximum transverse dimension of 27 mm. In one prostate a cavity of 27 (transverse) by 29 (anterior-posterior) by 43 (length) mm was created, with an estimated tissue removal of approximately 20 cc. Hemostasis with the Holmium laser was adequate in this canine prostate model. In addition to the acute tissue cavity created, a 1-2 mm rim of surrounding tissue coagulation was observed in each specimen.

CONCLUSION

The Holmium: Yttrium-Aluminum-Garnet laser wavelength is capable of acute prostatic tissue vaporization and deserves ongoing study with potential application in the surgical treatment of benign prostatic hyperplasia in men.

Neodymium:YAG laser coagulation prostatectomy: 3 years of experience with 227 patients

PURPOSE

For 3 years we prospectively followed a cumulative cohort of men who underwent neodymium:YAG laser coagulation prostatectomy to relieve bladder outlet obstruction to determine the safety, efficacy and durability of this procedure.

MATERIALS AND METHODS

A total of 227 men with symptomatic bladder outlet obstruction was treated with the Urolase side-firing laser fiber between October 15, 1991 and October 15, 1994. Voiding outcomes, including peak urinary flow rates, residual urine volumes and American Urological Association symptom scores, were measured with time, and immediate and long-term complications were assessed.

RESULTS

Median patient followup was 26 months (maximum 42). Significant improvement occurred in all measured voiding parameters, including 133% in peak flow rates and 61% in symptom scores 1 year postoperatively. Overall 87% of patients noticed improved quality of life as a result of surgery. Minimum postoperative followup was 6 months in all cases. Complications included prostatitis in 2.6% of patients, urethral stricture in 1.8%, bladder neck contracture in 4.4% and reoperation for residual prostate tissue in 5.3%.

CONCLUSIONS

Neodymium:YAG laser coagulation of the prostate represents an efficacious surgical intervention for symptomatic bladder outlet obstruction with minimal associated morbidity. Voiding outcomes are durable through 3 years.

Nd:YAG laser transurethral evaporation of the prostate (TUEP) for urinary retention

BACKGROUND AND OBJECTIVE

Little information is available regarding the effectiveness of laser prostatectomy in patients with urinary retention from benign prostatic hyperplasia since there is no paper specifically dealing with laser prostatectomy in patients in urinary retention.

STUDY DESIGN/MATERIALS AND METHODS

Twenty two unselected consecutive patients presenting with urinary retention due to benign prostatic hypertrophy underwent transurethral evaporation of the prostate (TUEP) using a neodymium:YAG laser and total internally reflecting side-firing free beam quartz fiber. All patients failed at least one voiding trial and averaged > 30 days of urinary catheter drainage preoperatively. A contact evaporation technique was used to evaporate a "TURP-like" channel in the prostatic fossa by means of a series of parallel evaporation troughs.

RESULTS

Eighteen of 22 patients completed 6 months of follow up. Two patients were lost to follow up and two failed TUEP. The average AUA score dropped from 26 to 9 at 1 month and to 3.4 by 6 months postoperatively. All patients who successfully underwent TUEP were urinating spontaneously by 10 days. Average time to catheter removal was 3.5 days. Maximal uroflow was 15.7 ml/sec at 1 month and 20.3 ml/sec by 6 months. Postvoid residual preoperatively averaged 784 ml and decreased to 76 ml by 1 month. Pre- and postoperative hematocrit and serum sodium values did not vary by more than 5%.

CONCLUSION

From this preliminary series we conclude that aggressive evaporation of prostatic tissue is feasible endoscopically and provides a reliable method of near bloodless removal of tissue.

Dosimetry studies utilizing the urolase right-angle firing neodymium:YAG laser fiber in the human prostate

BACKGROUND AND OBJECTIVE

Until recently, little or no objective data have been available to support either the choice of power setting or the timing of laser applications to achieve optimal tissue ablation in the human prostate. The objective of this study was to define quantitative dosimetry curves for the Urolase right angle laser fiber in human prostates. STUDY DESIGN MATERIALS AND METHODS: Transurethral Neodymium:YAG laser application was performed with the Urolase right-angle laser fiber in adult human prostates prior to planned radical surgery. Depth and volume of prostatic tissue coagulation for single, continuous laser applications were measured at variable power settings from 20 to 60 watts while holding total energy delivery constant. Then, holding the power setting constant at 40 watts, the extent of tissue coagulation was measured for variable treatment times from 60 to 120 seconds.

RESULTS

Peak tissue coagulation was observed at 40 watts up to a maximum of 14 mm tissue penetration and 4.23 cc volume coagulated following a single spot laser application. The mean depth of tissue coagulation at 40 watts power setting was 13.5 mm, with a mean volume of tissue coagulation of 3.68 cc. The mean depth of tissue penetration at 40 watts was more than 25% greater than that observed at 60 watts, and the mean volume of tissue coagulation was 190% greater than that observed at 60 watts. As treatment time was increased from 60 to 90 seconds, extent of tissue coagulation increased significantly. However, beyond 90 seconds continuous laser application at 40 watts, a plateau in tissue effects was observed, with minimal increase in tissue coagulation between 90 and 120 seconds. Histologic examination of prostates removed acutely showed heat-induced damage to both stromal and glandular epithelial elements in laser-treated areas. At 1 year, the prostatic urethra was lined with a normal transitional epithelium, and mild periurethral fibrosis with focal squamous metaplasia was seen.

CONCLUSION

Using the Urolase right-angle laser fiber, this study suggests that 40 watts power setting and 90 seconds continuous application time with a Neodymium:YAG laser source represent optimal treatment parameters to maximize prostatic tissue coagulation.

Visual laser ablation of the canine prostate with a diffusing fiber and an 805-nanometer diode laser

BACKGROUND AND OBJECTIVE

Although the popularity of visual laser ablation of the prostate (VLAP) as a treatment for symptomatic, benign prostatic hyperplasia (BPH) is increasing, the perceived advantages of VLAP over conventional transurethral electroresection of the prostate (TURP) is being debated because optimal technique and dosimetry for surgical lasers are still being refined. At this time, the 1.06 neodymium:yttrium-aluminum-garnet (Nd:YAG) laser and a laterally deflecting delivery system is the hardware combination most widely used for VLAP.

STUDY DESIGN/MATERIALS AND METHODS

Reported here is a study of an alternate system, a 805-nm diode laser (Diomed 25 Diomedics, The Woodlands, TX) with a cylindrically diffusing fiber (Surgimedics Inc., The Woodlands, TX). Eight mongrel dogs were prostatectomized by transurethral irradiation of the prostate with 15,000 J of diode laser energy delivered via a fiber that diffuses the energy in a 1.5-cm-long cylindrical pattern. The dogs were sacrificed and prostates harvested at 3 hours and 1,4,7,14,21,35, and 49 days after the procedure, fixed with 10% buffered formalin, and examined histologically.

RESULTS/CONCLUSIONS

It was found that this laser/fiber combination created volumes of tissue coagulation similar to those encountered in our previous work with the Nd:YAG laser in combination with both laterally deflecting and diffuser fibers, while offering the distinct advantages of simplified technique, lower cost hardware, and fewer postoperative complications in the dog model.