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Transmyocardial laser revascularization preserves regional myocardial perfusion: an MRI first pass perfusion study
Olaf M Mühling1, Ying Wang, Prasad Panse
1Section of Cardiovascular MRI, Department of Diagnostic Radiology, University of Minnesota Medical School, Minneapolis, MN, USA. omuehlin@med1.med.uni-muenchen.de
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).
Conclusion:
TMLR preserves regional myocardial perfusion and improves function as shown with MRPI.
Insights
Transmyocardial laser revascularization (TMLR) preserves myocardial perfusion and improves regional function in pigs with coronary artery occlusion, as demonstrated by quantitative magnetic resonance perfusion imaging (MRPI). This study utilized MRPI to assess perfusion before and after TMLR.
Area of Science:
- Cardiovascular Research
- Medical Imaging
- Surgical Innovation
Background:
- Transmyocardial laser revascularization (TMLR) is a debated procedure for improving myocardial perfusion.
- Quantitative magnetic resonance perfusion imaging (MRPI) offers a method to objectively assess perfusion changes.
Purpose of the Study:
- To evaluate the impact of TMLR on myocardial perfusion and function using MRPI in a porcine model.
- To compare perfusion in TMLR-treated animals versus untreated controls after coronary artery occlusion.
Main Methods:
- Pigs underwent left circumflex artery (LCx) occlusion followed by TMLR treatment in half the cohort.
- Magnetic resonance imaging (MRI) quantified resting perfusion, perfusion reserve (PR), regional wall thickening (RWT), and cardiac output (CO).
- MRPI data were correlated with microsphere-derived blood flow and infarct size (TTC staining).
Main Results:
- TMLR preserved resting perfusion in the lateral left ventricle (LV) myocardium compared to a significant decrease in untreated animals.
- Regional wall thickening improved in the LCx-dependent myocardium post-TMLR.
- While perfusion reserve did not differ significantly between groups, TMLR reduced LV necrosis compared to controls.
Conclusions:
- TMLR effectively preserves regional myocardial perfusion in the setting of coronary occlusion.
- The study demonstrates TMLR's ability to improve regional cardiac function as assessed by MRPI.
- Quantitative MRPI is a valuable tool for evaluating the efficacy of revascularization procedures.