Holmium laser ablation of recurrent strictures of urethra and bladder neck: preliminary results

The use of a 532-nm laser fitted with a balloon and a cylindrical light diffuser to treat benign biliary stricture: a pilot study

Endoscopic management of benign biliary stricture (BBS) remains challenging. Stenting is currently used for BBS management, but refractory BBS remains problematic. The aim of this study was to assess the safety and feasibility of a dilation balloon-equipped cylindrical light diffuser for BBS in a large animal model. A total of seven mini-pigs were used in the current study. Laser settings were chosen based on the findings of a previous animal study. Five animals were used in a preliminary study to establish process conditions. BBSs were created in the common bile ducts of the other two animals by intraductal radiofrequency ablation (RFA) via endoscopic retrograde cholangiography (ERC). At 4 weeks post-RFA, laser ablation was performed using a customized balloon-equipped cylindrical diffuser at 10 W for 10 s while maintaining balloon inflation for 10 s at 5 atm. A follow-up ERC was performed at 4 weeks post-laser ablation and the animals were sacrificed for histologic evaluation. BBS was observed in all animals by ERC at 4 weeks post-RFA. The mean bile duct stricture diameter in the two animals as determined by ERC was 0.8 mm. Laser ablations were performed without technical difficulty and no adverse event was encountered. At 4 weeks post-laser ablation, mean biliary stricture diameter had dilated to 1.6 mm on cholangiographic finding. On histologic examination, inflammatory cell infiltration in lamina propria and dense collagen deposition were observed, but there was no evidence of bile duct perforation. The devised balloon-equipped cylindrical laser light diffuser appears to be safe and feasible for the treatment of BBS. However, further studies and modifications are required before it can be applied clinically as a monotherapy.

Endoplasmic Reticulum Stress Activation in Alport Syndrome Varies Between Genotype and Cell Type

Alport syndrome is a hereditary progressive chronic kidney disease caused by mutations in type IV collagen genes COL4A3/4/5. X-linked Alport syndrome (XLAS) is caused by mutations in the COL4A5 gene and is the most common form of Alport syndrome. A strong correlation between the type of COL4A5 mutation and the age developing end-stage renal disease in male patients has been found. Mutation to the α (IV) chain causes retention of the protein to the endoplasmic reticulum lumen, which causes endoplasmic reticulum stress (ERS) and subsequent exertion of deleterious intracellular effects through the activation of ERS. The exact time point that mutant type IV collagen α chain exerts its deleterious effects remains elusive. In this study, we explored the relationship between the COL4A5 genotype and cell type in ERS activation. We obtained skin fibroblasts from Alport syndrome patients with different COL4A5 mutation categories [i.e., a missense mutation (c.4298G > T, p.Gly1433Val) in exon 47, a splicing mutation (c.1949–1G > A) in intron 25 and an insertion (c.573_c.574insG, p. Pro193Alafs*23) in exon 10], and then reprogrammed these fibroblasts into induced pluripotent stem cells (iPSCs). Interestingly, no significant dysregulation of ERS pathway markers was observed for the three COL4A5 mutant iPSCs; however, significant activation of ERS in COL4A5 mutant fibroblasts was observed. In addition, we found that the activation levels of some ERS markers in fibroblasts varied among the three COL4A5 mutation types. Mutant COL4A5 proteins were demonstrated to have different effects on cells at different stages of ontogenesis, providing a theoretical basis for choosing the timing of intervention. The observed differences in activation of ERS by the COL4A5 mutant fibroblasts may contribute to the intracellular molecular mechanisms that describe the correlation between genotype and clinical features in XLAS.

Experience of 138 Transurethral Urethrotomy With Holmium:YAG Laser

Introduction: Many valid option modalities are available for the management of urethral stricture disease (USD), such as internal urethrotomy which has the success rates of 33%-60%. The aim of this study was to assess the outcome of holmium: YAG (Ho: YAG) laser urethrotomy (HLU). Methods: One hundred thirty-eight patients with urethral stricture with the mean age of 48±3.03 years old treated by HLU from March 2011 to August 2017. The main purpose of this investigation was to evaluate mean operation time, stricture recurrence rate and post-operation Qmax and complications of transurethral HLU. Results: The most common cause of USD was trauma in 82 (59.4%) patients. Mean laser operation time, mean hospital stay and mean postoperative duration of catheterization were 23.08 ± 9.1 minutes, 19.02 ± 10.7 hours and 10.3 ± 1.05 days respectively. The mean Qmax was 8.3 ± 2.07 mL/s before surgery and 16 ±3.1 mL/s afterward. At the end of 12 months follow-up, a total of 37 (26.8%) patients developed recurrence of the stricture. Patients with posterior, longer urethral strictures and previous history of interventions have more recurrence rate of the stricture. Conclusion: HLU is minimally invasive and seems to be an effective and safe management option for primary, short, urethral strictures. The hospital stay is remarkably short and complications are negligible.

Efficacy of holmium laser urethrotomy and intralesional injection of Santosh PGI tetra-inject (Triamcinolone, Mitomycin C, Hyaluronidase and N-acetyl cysteine) on the outcome of urethral strictures

Introduction

To study the efficacy of holmium laser urethrotomy with intralesional injection of Santosh PGI tetra-inject (Triamcinolone, Mitomycin C, Hyaluronidase and N-acetyl cysteine) in the treatment of urethral strictures.

Material and methods

A total of 50 patients with symptomatic urethral stricture were evaluated by clinical history, physical examination, uroflowmetry and retrograde urethrogram preoperatively. All patients were treated with holmium laser urethrotomy, followed by injection of tetra-inject at the urethrotomy site. Tetra-inject was prepared by diluting acombination of 40 mg Triamcinolone, 2 mg Mitomycin, 3000 UHyaluronidase and 600 mg N-acetyl cysteine in 5–10 ml of saline, according to the stricture length. An indwelling 18 Fr silicone catheter was left in place for 7–10 days.All patients were followed-up for 6-18 months postoperatively by history, uroflowmetry, and if required, retrograde urethrogram and micturating urethrogram every 3 months.

Results

41 (82%) patients had asuccessful outcome,whereas 9 (18%) had recurrences during a follow-up ranging from 6–18 months. In <1 cm length strictures, the success rate was 100%, while in 1–3 cm and >3 cm lengthsthe success rates were 81.2% and 66.7% respectively. This modality, thus, has an encouraging success rate, especially in those with short segment urethral strictures (<3 cm).

Conclusions

Holmium laser urethrotomy with intralesional injection ofSantosh PGI tetra-inject (Triamcinolone, Mitomycin C, Hyaluronidase, N-acetyl cysteine) is a safe and effective minimally-invasive therapeutic modality for short segment urethral strictures.

Therapeutic applications of lasers in urology: an update

There has been renewed interest in the use of lasers for minimally invasive treatment of urologic diseases in recent years. The introduction of more compact, higher power, less expensive and more user-friendly solid-state lasers, such as the holmium:yttrium-aluminum-garnet (YAG), frequency-doubled neodymium:YAG and diode lasers has made the technology more attractive for clinical use. The availability of small, flexible, biocompatible, inexpensive and disposable silica optical fiber delivery systems for use in flexible endoscopes has also promoted the development of new laser procedures. The holmium:YAG laser is currently the workhorse laser in urology since it can be used for multiple soft- and hard-tissue applications, including laser lithotripsy, benign prostate hyperplasia, bladder tumors and strictures. More recently, higher power potassium-titanyl-phosphate lasers have been introduced and show promise for the treatment of benign prostatic hyperplasia. On the horizon, newer and more effective photosensitizing drugs are being tested for potential use in photodynamic therapy of bladder and prostate cancer. Additionally, new experimental lasers such as the erbium:YAG, Thulium and Thulium fiber lasers, may provide more precise incision of soft tissues, more efficient laser lithotripsy and more rapid prostate ablation. This review provides an update on the most important new clinical and experimental therapeutic applications of lasers in urology over the past 5 years.

Efficacy of holmium laser urethrotomy in combination with intralesional triamcinolone in the treatment of anterior urethral stricture

Purpose

To evaluate the outcome of visual internal urethrotomy with a holmium:yttrium-aluminum-garnet laser along with intralesional triamcinolone injection.

Materials and Methods

Patients with an anterior urethral stricture less than 3 cm in length were evaluated by clinical history, physical examination, uroflowmetry, and retrograde urethrogram preoperatively. All patients were treated with holmium laser urethrotomy and intralesional triamcinolone (80 mg) injection under general or regional anesthesia. An 18 F urethral catheter was placed for 5 days. All patients were followed up for 12 months postoperatively by history, uroflowmetry, and if required, retrograde urethrogram or urethroscopy every 3 months.

Results

The mean age of the patients was 42.9 years (range, 14 to 70 years). The overall recurrence rate was 24%. The success rate in patients with strictures less than 1 cm in length was 95.8%, whereas that in patients with strictures of 1 to 3 cm in length was 57.7% (p=0.002). The outcome did not depend on age, duration of symptoms, etiology, or location of stricture.

Conclusions

Holmium laser urethrotomy with intralesional triamcinolone is a safe and effective minimally invasive therapeutic modality for urethral strictures. This procedure has an encouraging success rate, especially in those with stricture segments of less than 1 cm in length.

Thulium laser urethrotomy for urethral stricture: a preliminary report

BACKGROUND AND OBJECTIVES

The outcome of thulium laser urethrotomy for patients with urethral stricture had not been reported. The purpose of this study was to evaluate outcome of endourethrotomy with the thulium laser as a minimally invasive treatment for urethral stricture.

MATERIALS AND METHODS

Twenty-one consecutive patients with urethral stricture were evaluated by retrograde uroflowmetry, International Prostate Symptom Score (IPSS), and quality of life preoperatively at a single academic center. All patients were treated with thulium laser urethrotomy. All patients were followed up for 12-24 months postoperatively by uroflowmetry and by retrograde with voiding cystourethrogram every 3 months. And all patients were followed up by mailed questionnaire, including IPSS and quality of life.

RESULTS

Retrograde endoscopic thulium laser urethrotomy was performed in all 21 patients. Most patients (N = 16; 76.2%) did not need any reintervention. Five patients developed recurrent strictures, of them two patients were treated by another laser urethrotomy, one patient was treated by open urethroplasty with buccal mucosa and the other two patients' reintervention were treated by urethral dilation. No intraoperative complications were encountered, although in 9.5% (N = 2) of patients, a urinary tract infection was diagnosed postoperatively. No gross hematuria occurred. Including two patients treated with repeat laser urethrotomy, 17(81.0%) showed good flow of urine (Q(ave)>16.0 ml/second) and adequate caliber urethra in retrograde urethrogram (RGU) 12 months after operation. Three (14.3%) patients showed narrow stream of urine (Q(ave)<8.0 ml/second) and urethral dilation was done every month or 2 months. There was one patient whose Q(ave) was between 8.0 and 16.0 ml/second. And this patient was treated by neither urethral dilation nor another laser urethrotomy.

CONCLUSIONS

The thulium laser urethrotomy was a safe and effective minimally invasive therapeutic modality for urethral stricture.

Transurethral 2-microm laser in the treatment of urethral stricture

OBJECTIVES

To evaluate the curative efficacy of transurethral 2-mum thulium laser urethrotomy in the treatment of urethral stricture.

METHODS

Two hundred and thirty-eight patients suffering from urethral stricture, all male, aged 47.3 (36-58), underwent transurethral 2-mum thulium laser urethrotomy. The maximum flow rate (MFR), the international prostatic symptom score (IPSS) and the quality of life (QoL) were measured before operation, immediately following the removal of the catheter, and 3 and 6 months postoperatively.

RESULTS

The surgery was performed for all the patients with no rectum injury, urine leakage or massive blood loss. All the patients got free urination immediately following the catheter removal with the mean MFR improved from (3.2 + or - 0.3) ml/s preoperatively to (16.7 + or - 3.1) ml/s, which kept steady to (18.7 + or - 2.9) and (19.2 + or - 2.8) ml/s, respectively 3 and 6 months after operation. IPSS significantly improved from 28.3 + or - 5.8 preoperatively to 7.1 + or - 1.9, 6.4 + or - 1.5 and 5.3 + or - 1.3, respectively when catheter removal and 3 and 6 months after operation. Also during the corresponding period, mean QoL improved from 5.4 + or - 1.1 to 1.1 + or - 0.3, 0.9 + or - 0.2 and 0.8 + or - 0.2. 195, patients got permanent uninterrupted urination without recurrence in the whole 6 months of follow-up. Forty-three patients got recurrence and seven patients encountered with incontinence 1-3 weeks (mean 13.8 days) after catheter removal, but they all got final cure after periodic urethral dilatation and physical exercise.

CONCLUSIONS

Transurethral 2-mum thulium laser is safe and efficient in the treatment of urethral stricture.

Bladder neck incision using a 70 W 2 micron continuous wave laser (RevoLix)

Postoperative bladder neck contracture continues to be a frequently occurring problem. Bladder neck incision (BNI) continues to be the standard mode of treatment. However, the recurrence rate appears to be high. Therefore alternative treatment options are still needed. We report about initial experience with the RevoLix 2 micron continuous wave laser for BNI after a 1-year follow-up. Fourteen patients with a second or third recurrence of bladder neck contracture after primary surgery were included into the trial. All patients reported high-grade obstruction and residual urine. BNI was performed using a 70 W 2-micron continuous wave laser (RevoLix). This laser utilizes the thulium as an active ion. Laser incisions were applied in 5 and 7o'clock lithotomy position. Remaining tissue was vaporized. Assessed outcomes were improvement in AUA-symptom-score, quality of life index and uroflowmetry, measured preoperatively, after 2 and 12 months postoperatively. Mean operating time was 7 min, mean catheterization time was 6.5 h. The mean maximum uroflow-rate improved from 9 ml/s preoperatively to 23 ml/s. AUA-symptom score improved from 22 to 8 points and quality of life index improved from four to one. Two patients developed restenosis so far. Although longer follow-up and larger sample size are needed, BNI with the RevoLix laser is a fast, safe and promising procedure in recurrent bladder neck sclerosis.

Holmium:YAG laser for treatment of strictures of vesicourethral anastomosis after radical prostatectomy

BACKGROUND AND PURPOSE

Strictures of the vesicourethral anastomosis (VUA) following radical prostatectomy tend to recur. We used the holmium:YAG laser for treatment of recurrent stricture of the VUA. We evaluated the technique and its efficacy.

PATIENTS AND METHODS

In 10 patients, the Ho:YAG laser was used with a 365-mum fiber at a setting of 2 J and frequency 10 to 20 Hz, creating a deep incision of the scar tissue at the 6 o'clock position. This was followed by a vaporizing resection of the remaining scar tissue between 3 and 9 o'clock. We aimed to vaporize up to well-vascularized surrounding tissue. Retrospectively, the charts were reviewed for hospital stay, voiding complaints, recurrence of stenosis, complications, and flow rates. The mean follow-up was 18 months.

RESULTS

There were no operative complications. After removal of the catheter, all patients could void without difficulty. No re-treatment was needed for recurrent stenosis. Any existing irritative voiding complaints or incontinence did not change after treatment. In all patients, the flow pattern improved: the mean maximum flow rate increased, and the mean postvoiding residual volume decreased.

CONCLUSION

The Ho:YAG laser seems to be a safe and effective treatment for first or recurrent strictures of the VUA after radical prostatectomy.

High-power laser vaporization of the canine prostate using a 110 W Thulium fiber laser at 1.91 microm

INTRODUCTION

The Thulium fiber laser may have several advantages over current urology lasers, including smaller size, more efficient operation, improved spatial beam quality, more precise tissue incision, and operation in pulsed or continuous-wave modes. Previous laser-tissue interaction studies utilizing the Thulium fiber laser have been limited to laser powers of less than 5 W, restricting potential medical applications. This study describes the preliminary testing of a high-power Thulium fiber laser for vaporization of the canine prostate, ex vivo.

STUDY DESIGN/MATERIALS AND METHODS

A continuous-wave, 110-W Thulium fiber laser operating at a wavelength of 1.91 microm, delivered 88.5+/-2.3 W of power through a 600-microm-core silica fiber for non-contact vaporization of canine prostates (n = 6).

RESULTS

The Thulium fiber laser vaporized prostate tissue at a rate of 0.83+/-0.11 g/minute. The thermal coagulation zone measured 500-2,000 microm, demonstrating the potential for hemostasis.

CONCLUSIONS

The high-power Thulium fiber laser is capable of rapid vaporization and coagulation of the prostate. In vivo animal studies are currently being planned for evaluation of the Thulium fiber laser for potential treatment of benign prostate hyperplasia (BPH).

Comparison of erbium:yttrium-aluminum-garnet and holmium:yttrium-aluminum-garnet lasers for incision of urethra and bladder neck in an in vivo Porcine model

OBJECTIVES

To evaluate, in an animal model, differences in wound healing and scar formation in healthy urethra and bladder neck incised with the erbium (Er):yttrium-aluminum-garnet (YAG) and holmium (Ho):YAG lasers.

METHODS

In each of 18 domestic pigs, three 1-cm-long incisions were made, two at the bladder neck and one in the mid-urethra, using either the Er:YAG laser (9 pigs) or the Ho:YAG laser (9 pigs). In each laser group, 3 animals were killed on postoperative days 0, 6, and 14. The width of collateral damage, as evidenced by coagulation necrosis and granulation tissue at the wound base, and the incision depth were evaluated during tissue analysis.

RESULTS

The collateral damage with the Er:YAG laser at postoperative day 0, 6, and 14 was 20 +/- 5, 900 +/- 100, and 430 +/- 100 microm, respectively. The collateral damage with the Ho:YAG laser was 660 +/- 110, 2280 +/- 700, and 1580 +/- 250 microm, respectively. The amount of granulation tissue was significantly less (P <0.05) at all time points with the Er:YAG laser. Similarly, the incision depths for the Er:YAG and Ho:YAG laser at postoperative day 6 (1100 +/- 200 microm versus 1500 +/- 300 microm, respectively) and 14 (670 +/- 140 microm versus 1240 +/- 140 microm, respectively) were also significantly less (P <0.05) for the Er:YAG laser group, indicating faster healing of the wound created.

CONCLUSIONS

In this in vivo animal study, incisions in the urethra and bladder neck made with the Er:YAG laser healed faster and with less scar formation than incisions made with the Ho:YAG laser.

Optimization of the Erbium:YAG laser for precise incision of ureteral and urethral tissues: in vitro and in vivo results

BACKGROUND AND OBJECTIVES

Tissue damage during endoscopic treatment of urethral and ureteral strictures may result in stricture recurrence. The Erbium:YAG laser ablates soft tissues with minimal peripheral damage and may be a promising alternative to cold knife and Holmium:YAG laser for precise incision of urological strictures.

STUDY DESIGN/MATERIALS AND METHODS

Optimization of the Er:YAG laser was conducted using ex vivo porcine ureteral and canine urethral tissues. Preliminary in vivo studies were also performed in a laparoscopic porcine ureteral model with exposed ureter. Laser radiation with a wavelength of 2.94 microm, pulse lengths of 8, 70, and 220 microseconds, output energies of 2-35 mJ, fluences of 1-25 J/cm2, and pulse repetition rates of 5-30 Hz, was delivered through 250-microm and 425-microm core germanium oxide optical fibers in direct contact with tissue.

RESULTS

Ex vivo perforation thresholds measured 2-4 J/cm2, with ablation rates of 50 microm/pulse at fluences of 6-11 J/cm2. In vivo perforation thresholds were approximately 1.8 J/cm2, with the ureter perforated in less than 20 pulses at fluences greater than 3.6 J/cm2. Peripheral thermal damage in tissue decreased from 30 to 60 microm to 10-20 microm as the laser pulse length decreased from 220 to 8 microseconds. Mechanical tissue damage was observed at the 8 microseconds pulse duration.

CONCLUSIONS

The Er:YAG laser, operating at a pulse duration of approximately 70 microseconds, a fluence greater than approximately 4 J/cm2, and a repetition rate less than 20 Hz, is capable of rapidly incising urethral and ureteral tissues with minimal thermal and mechanical side-effects.

Management of obliterated urinary segments using a laser fiber for access

PURPOSE

We describe a modification of the cut to the light and core-through procedures using a laser fiber to gain through and through access for treatment of complete occlusion of the ureter or urethra.

MATERIALS AND METHODS

Three patients presented with complete obliteration of the ureter (2) and vesicourethral anastomosis (1). In each case the laser fiber was advanced through the obliterated segment under direct vision and then exchanged for a standard guide wire using an open ended catheter.

RESULTS

Through and through access was obtained in all 3 cases and allowed subsequent incision for repair. In all 3 patients the area of incision was stented and urinary continuity was restored.

CONCLUSIONS

Loss of access can lead to complications and termination of any endoscopic procedure. Use of the laser fiber to incise through the obliterated segment and subsequently act as a guide wire in our experience minimized the possibility for loss of access. The disadvantage is the cost of the laser fiber, which cannot be reused. Use of a laser fiber as a guide wire can be a viable and effective option for gaining access across strictures when alternative methods fail.

Potential applications of the erbium:YAG laser in endourology

The holmium:YAG laser has become the laser of choice in endourology because of its multiple applications in the fragmentation of kidney stones, incision of strictures, and coagulation of tumors. This paper describes the potential use of a new laser, the erbium:YAG laser, for applications in endourology. Recent studies suggest that the Er:YAG laser may be superior to the Ho:YAG laser for precise ablation of strictures with minimal peripheral thermal damage and for more efficient laser lithotripsy. The Er:YAG laser cuts urethral and ureteral tissues more precisely than does the Ho:YAG laser, leaving a residual peripheral thermal damage zone of 30 +/- 10 microm compared with 290 +/- 30 microm for the Ho:YAG laser. This result may be important in the treatment of strictures, where residual thermal damage may induce scarring and result in stricture recurrence. The Er:YAG laser may represent an alternative to the cold knife and Ho:YAG laser in applications where minimal mechanical and thermal insult to tissue is required.