title: Induction of angiogenesis after TMR: a comparison of holmium: YAG, CO2, and excimer lasers.
abstract: BACKGROUND
  Transmyocardial laser revascularization (TMR) is an emerging treatment for end-stage coronary artery disease. A variety of lasers are currently available to perform the procedure, although their relative efficacy is unknown. The purpose of this study was to compare changes in myocardial blood flow and function 6 months after TMR with holmium:yttrium-aluminum-garnet (holmium:YAG), carbon dioxide (CO2), and xenon chloride excimer lasers in a model of chronic ischemia.
  
  
  METHODS
  Miniswine underwent subtotal (90%) left circumflex coronary stenosis. Baseline positron emission tomography and dobutamine stress echocardiography were performed to document hibernating myocardium in the left circumflex coronary artery distribution. Animals were then randomized to sham redo-thoracotomy (n = 5) or TMR using a holmium:YAG (n = 5), CO2 (n = 5) or excimer (n = 5) laser. Six months postoperatively, the positron emission tomography and dobutamine stress echocardiography studies were repeated and the animals sacrificed.
  
  
  RESULTS
  In animals undergoing TMR with holmium: YAG and CO2 lasers, a significant improvement in myocardial blood flow to the lased left circumflex regions was seen. No significant change in myocardial blood flow was seen in sham- or excimer-lased animals. There was a significant improvement in regional stress function of the lased segments 6 months postoperatively in animals undergoing holmium:YAG and CO2 laser TMR that was consistent with a reduction in ischemia. There was no change in wall motion in sham- or excimer-lased animals. Significantly greater neovascularization was observed in the holmium:YAG and CO2 lased regions than with either the sham procedure or excimer TMR.
  
  
  CONCLUSIONS
  Transmyocardial laser revascularization with either holmium:YAG or CO2 laser improves myocardial blood flow and contractile reserve in lased regions 6 months postoperatively. These changes were not seen following excimer TMR or sham thoracotomy, suggesting that differences in laser energy or wavelength or both may be important in the induction of angiogenesis.
authors.affiliation: Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: G C
authors.initials: GC
authors.lastname: Hughes
authors.forename: A P
authors.initials: AP
authors.lastname: Kypson
authors.forename: B H
authors.initials: BH
authors.lastname: Annex
authors.forename: B
authors.initials: B
authors.lastname: Yin
authors.forename: J D
authors.initials: JD
authors.lastname: St Louis
authors.forename: S S
authors.initials: SS
authors.lastname: Biswas
authors.forename: R E
authors.initials: RE
authors.lastname: Coleman
authors.forename: T R
authors.initials: TR
authors.lastname: DeGrado
authors.forename: C L
authors.initials: CL
authors.lastname: Donovan
authors.forename: K P
authors.initials: KP
authors.lastname: Landolfo
authors.forename: J E
authors.initials: JE
authors.lastname: Lowe
mesh_terms: D000535:Aluminum; D000818:Animals; D002245:Carbon Dioxide; D006695:Holmium; D053685:Laser Therapy; D007834:Lasers; D008297:Male; D009204:Myocardial Revascularization; D017682:Myocardial Stunning / Q000473:pathology; D018919:Neovascularization, Physiologic; D013552:Swine; D014055:Tomography, Emission-Computed; D015019:Yttrium
chemical_list: D002245:Carbon Dioxide; D015019:Yttrium; D000535:Aluminum; D006695:Holmium