Laser tissue welding: a urological surgeon's perspective

Overview on the Evolution of Laser Welding of Vascular and Nervous Tissues

Laser welding presents a core position in the health sector. This process has had an outstanding impact on the surgical procedures from many medical areas, such as on vascular and nervous surgeries. The aim of the present research is to present an overview on the evolution of laser welding of vascular and nervous tissues. These surgeries present many advantages, such as an absence of foreign-body reactions and aneurysms and good tensile strengths. However, despite the sutureless nature of the process, complementary sutures have been applied to support the procedure success. An important concern in vascular and nervous laser welding is the thermal damage. The development of temperature-controlled feedback systems has reduced this concern with a very precise control of the laser parameters. The bonding strength of vascular and nerve laser welds can be enhanced with the application of solder solutions, bonding materials, and laser-activated dyes. Alternative techniques to laser welding, such as photochemical tissue bonding and electrosurgical high-frequency technologies, have also been tested for vascular and nervous repairs.

Closure of skin incision by dual wavelength (980 and 1064 nm) laser application

Thermal effect of dual wavelength (980 and 1064 nm) laser application in skin incision closure was assessed on 18 male and female Wister rats. 1-cm-long incisions were made on the shaved dorsal region of 220-250 g animals. The incisions were closed by laser irradiation at 1 W and exposure time, 5 seconds in continuous-wave mode (CW) and 1 W and exposure time, 10 seconds in pulsed mode to deliver total energies of 5 J and 10 J per spot onto the incisions, respectively. Animals from each group were sacrificed at 0th, 4th, and 7th days and the skin samples of the weld area were excised for histological analysis using Hematoxylin and Eosin (H & E) stain. Mean thermally altered area (TAA) of CW-mode laser-treated groups was found to increase significantly (p < 0.05) compared with pulsed mode laser treated group at 0th and 4th days post-irradiation while no significant difference (p > 0.05) was statistically found at 7th day post-irradiation. Moreover, tighter closure was observed with CW group at 7th day post-irradiation. We thus conclude that 1 W, 5 J for 5 seconds CW mode laser application of 980 and 1064 nm combined beam form in skin incision closure was found to have absolute wound healing capability with minimal thermal alteration.

Laser welding of vesicovaginal fistula--outcome analysis and long-term outcome: single-centre experience

INTRODUCTION AND HYPOTHESIS

The aim of this study is to evaluate the efficacy and safety of laser welding of vesicovaginal fistula (VVF) at our centre.

METHODS

Between January 1, 2001 and January 3, 2010, eight patients underwent laser welding of vesicovaginal fistula. The mean age was 44 years (35-55). The VVF were primary (failing to heal following conservative management) in five and secondary (recurring following primary repair) in three cases. The mean fistula size was 3 mm (range, 2-4). Neodymium yttrium aluminium garnet (YAG) laser was used for the initial case, and in the remaining seven cases, holmium YAG laser was used for circumferential welding of the fistula. Following the procedure, a catheter was kept for 3 weeks. The mean hospitalisation period was 1 day. The mean follow-up is 47 months (2-110).

RESULTS

Seven patients were dry after catheter removal. In one patient, procedure was abandoned due to bleeding.

CONCLUSIONS

Laser welding of VVF is a simple, safe and efficacious procedure in a select group of patients.

Closure of skin incisions by laser-welding with a combination of two near-infrared diode lasers: preliminary study for determination of optimal parameters

Laser welding has the potential to become an effective method for wound closure and healing without sutures. Closure of skin incisions by laser welding with a combination of two near-infrared lasers (980 and 1064 nm), was performed for the first time in this study. One centimeter long, full-thickness incisions were made on the Wistar rat's dorsal skin. The efficiencies of laser-welding with different parameters were investigated. Incision-healing, histology examination, and a tensile strength test of incisions were recorded. Laser welding with the irradiance level of 15.9 W∕cm(2) for both 980 and 1064-nm lasers and exposure time of 5 s per spot in continuous wave mode yielded a more effective closure and healing with minimal thermal damage, faster recovery, and stronger apposition in comparison with a suturing technique. The conclusion is that skin welding with a combination of two near-infrared diode lasers can be a good candidate for incision closure, and further investigations are in progress for clinical use.

Circumcision in hemophilia: a cost-effective method using a novel device

BACKGROUND/PURPOSE

The authors conducted a prospective clinical study to see whether the need for and the cost of factor substitution after circumcision can be reduced using a novel device for bloodless circumcision in boys with hemophilia.

METHODS

Forty-five boys with hemophilia (age range, 1.5 to 25 years; median age, 11; 40 with hemophilia A, 5 with hemophilia B; weight range, 9 to 75 kg; median weight, 30 kg) were circumcised in our department between 1996 and 2001. Severity of the disease was mild in 9 cases, moderate in 11, and severe in 25. After starting systemic prophylaxis including factor substitution and DDAVP (desmopressin acetate) in reduced doses, all patients underwent circumcision under local anesthesia using a modified straight clamp and a battery-operated diathermic knife specially designed for bloodless circumcision. Duration of factor replacement ranged between 7 and 18 days, and the hospitalization period was 2 to 5 days according to severity of the disease. The last 19 patients were given tranexamic acid orally for 7 days after surgery.

RESULTS

Transient minimal bleeding was observed in 5 patients and easily responded to factor administration. Moderate edema and hyperemia along the excision line owing to the diathermic effect of the device lasted for 3 to 4 days. Normal cosmetic appearance was regained within 7 to 21 days. Excellent patient and family satisfaction was reported. The average cost of the operation was calculated as 81 dollars, 144 dollars, and 243 dollars per kilogram in mild, moderate, and severe cases, respectively.

CONCLUSIONS

Bloodless circumcision with "diathermic knife" is a practical and reliable alternative for boys with hemophilia. Enhancement of local hemostasis using such an alternative device may reduce the need for factor substitution and, accordingly, the cost of circumcision in hemophiliacs, down to 50%.

Time Course and Histology of Urethrocutaneous Fistula Formation in a Porcine Model of Urethral Healing

OBJECTIVE

Urethrocutaneous fistula is a well-known complication of hypospadias surgery and is reported in 5-10% of repairs. Using a previously described juvenile pig model, we present a histological analysis of the healing of the ventral aspect of the urethral repair and describe the histological mechanism of fistula formation.

MATERIALS AND METHODS

Twelve juvenile pigs underwent ventral, longitudinal urethral incision and closure over a 5-French feeding tube. The ventral aspect was closed in running fashion using two closure techniques and three suture types in each animal. Three animals were sacrificed on postoperative day 3, three on day 5, three on day 12, one on day 14, and two on day 21. Closure was one-layered incorporating urethral mucosa in the animals sacrificed on days 3, 5, and 21. An extra-mucosal suture technique was used in the group sacrificed on day 12. Sections of the penis were cut, paraffin embedded, and treated with Hematoxylin and Eosin staining.

RESULTS

Fistulae were seen in 12 specimens and in association with each suture type. Fewer sections of the extra-mucosal technique showed fistulization. Fistulae lined with immature epithelium were seen by day 5. Mature fistulae were observed by day 12. Skin epithelium and urethral mucosa migrated along suture tracts. By days 12 and 21, in addition to mature fistulae, several sections showed well-healed ventral repairs with clearly extramucosal suture tracts.

CONCLUSIONS

Fistula formation begins early in the healing process after ventral urethral repair. Incorporation of urethral mucosa in the ventral repair is a substrate for fistula formation with rapid migration of urethral mucosa and skin epithelium into suture tracts. The importance of a multi-layered repair and extra-mucosal suture technique are thus emphasized with respect to urethral repair. Whether the mucosal or dermal migration along suture tracts can be attenuated or prevented by changing the biochemical environment awaits further investigation.

Enhanced adenoviral-vector mediated gene transfer using human albumin solder

BACKGROUND AND OBJECTIVE

Laser tissue welding with human albumin solder (HAS) has been used as an alternative method of wound closure. Adenoviral vectors have been used to introduce various cytokine genes into wounds to accelerate wound closure. In the present study, we were interested in the effect of HAS on adenoviral vector transfer of the beta-galactosidase (beta-gal) gene in vitro and in vivo.

STUDY DESIGN/MATERIALS AND METHODS

3T3 fibroblasts were used to study the effect of HAS on beta-gal gene transfer in vitro. The presence of beta-gal was determined by Western blot, and its activity by a colorimetric assay. A punch biopsy model of wound healing in pigs was used for in vivo experiments.

RESULTS

HAS increased the efficiency of adenoviral-mediated beta-gal transduction and stabilized the adenovirus at room temperature. HAS protected adenovirus from inactivation by laser, both in vitro and in vivo.

CONCLUSIONS

HAS may stabilize adenoviral vectors to deliver cytokine genes in future wound healing experiments.

Ophthalmic surgery in haemophilia

A wide range of ophthalmic surgical procedures were conducted in five patients with haemophilia of varying severity (one severe and four mild) aged between 8 and 75 years. The operations included intraocular lens implantation, trabeculectomy and vitrectomy. Successful postoperative outcome with haemostasis was achieved in all patients with moderate use of clotting factor concentrates (3000-7000 IU), simultaneous use of oral epsilon amino caproic acid therapy and intravenous deamino-8-D-arginine vasopressin (desmopressin; DDAVP) wherever feasible. None of the patients had circulating inhibitor. One of the patients with milder disease (FVIII 32%) was referred to us after he was operated on for hyphaema elsewhere, without prior knowledge of his diagnosis of haemophilia. Thus, satisfactory eye surgery in patients with haemophilia is possible with a restricted amount of factor concentrates with gratifying results.