title: 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.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Urology, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors.forename: Ioannis M
authors.initials: IM
authors.lastname: Varkarakis
authors.forename: Takeshi
authors.initials: T
authors.lastname: Inagaki
authors.forename: Mohamad E
authors.initials: ME
authors.lastname: Allaf
authors.forename: Theresa Y
authors.initials: TY
authors.lastname: Chan
authors.forename: Craig G
authors.initials: CG
authors.lastname: Rogers
authors.forename: E James
authors.initials: EJ
authors.lastname: Wright
authors.forename: Nathaniel M
authors.initials: NM
authors.lastname: Fried
mesh_terms: D000535:Aluminum; D000818:Animals; D002921:Cicatrix / Q000209:etiology* / Q000473:pathology; D004871:Erbium; D005260:Female; D006097:Granulation Tissue / Q000473:pathology; D006695:Holmium; D053685:Laser Therapy / Q000009:adverse effects* / Q000295:instrumentation; D007834:Lasers / Q000009:adverse effects*; D009336:Necrosis; D034421:Sus scrofa; D014521:Urethra / Q000473:pathology / Q000601:surgery*; D001743:Urinary Bladder / Q000473:pathology / Q000601:surgery*; D014945:Wound Healing; D015019:Yttrium
chemical_list: C503779:yttrium-aluminum-garnet; D015019:Yttrium; D004871:Erbium; D000535:Aluminum; D006695:Holmium