title: Transmyocardial laser revascularization preserves regional myocardial perfusion: an MRI first pass perfusion study.
abstract: OBJECTIVE
  It is controversial whether transmyocardial laser revascularization (TMLR) improves myocardial perfusion. Therefore, we assessed myocardial perfusion before and after TMLR with quantitative magnetic resonance perfusion imaging (MRPI) in an animal study.
  
  
  METHODS
  One week after partial occlusion of the left circumflex artery (LCx) in 12 pigs, resting perfusion (ml/g/min), perfusion reserve (PR) with adenosine, regional wall thickening (RWT), cardiac output (CO) were quantified with MRI in the LCx (lateral) and LAD (septal) dependent myocardium. Subsequently, six animals were treated with TMLR of the lateral left ventricle (LV). Six animals were left untreated. A final MR was performed 8 weeks later. MRPI data were compared to microsphere-derived blood flow and % LV necrosis (TTC). 'Normal' myocardial perfusion was assessed with MRPI in 12 non-instrumented animals.
  
  
  RESULTS
  Resting perfusion prior to TMLR (0.7-0.9+/-0.3) in the LV-lateral myocardium was preserved after TMLR (1.0+/-0.3) and decreased without TMLR (0.3+/-0.1, P<0.05). There was a significant difference (P<0.01) between the TMLR treated and untreated group. Compared to 'normals' (1.2+/-0.2) perfusion of the LV-lateral wall was not different after TMLR but reduced (P<0.02) without TMLR. PR was not different between TMLR-treated (1.4+/-0.9) and untreated (1.9+/-0.6) group but was reduced (P<0.04) compared to PR of 'normals' (2.7+/-0.8). MRPI data and microsphere-derived perfusion were significantly correlated (P<0.01). RWT in the LCx-dependent myocardium improved (P<0.02) after TMLR. CO decreased (P<0.02) and TTC-staining indicated more LV-necrosis without TMLR (6.6+/-1.6 vs. 3.7+/-1.5, P<0.01).
  
  
  CONCLUSIONS
  TMLR preserves regional myocardial perfusion and improves function as shown with MRPI.
authors.affiliation: Section of Cardiovascular MRI, Department of Diagnostic Radiology, University of Minnesota Medical School, Minneapolis, MN, USA. omuehlin@med1.med.uni-muenchen.de
authors.forename: Olaf M
authors.initials: OM
authors.lastname: Mühling
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Prasad
authors.initials: P
authors.lastname: Panse
authors.forename: Michael
authors.initials: M
authors.lastname: Jerosch-Herold
authors.forename: Mary M
authors.initials: MM
authors.lastname: Cayton
authors.forename: L Samuel
authors.initials: LS
authors.lastname: Wann
authors.forename: Mahmood M
authors.initials: MM
authors.lastname: Mirhoseini
authors.forename: Norbert M
authors.initials: NM
authors.lastname: Wilke
mesh_terms: D000818:Animals; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008833:Microcirculation; D023421:Models, Animal; D017202:Myocardial Ischemia / Q000473:pathology / Q000601:surgery*; D015425:Myocardial Reperfusion; D009204:Myocardial Revascularization; D009206:Myocardium / Q000473:pathology*; D011897:Random Allocation; D012039:Regional Blood Flow; D013552:Swine