Objectives: The purpose of this validation study was the quantitative assessment of myocardial perfusion during graded coronary stenosis by analysis of FCI as compared to gold standard fluorescent microspheres (FM).
Background: Fluorescent cardiac imaging (FCI) is a novel technology to visualize coronary vessels and myocardial perfusion intraoperatively using the dye indocyanine green with an infrared sensitive imaging device.
Methods: Graded flow-limiting (FLS) and non-flow-limiting stenoses (NFLS) of the left anterior descending coronary artery (LAD) were created in 20 open-chest pigs. After pharmacological vasodilatation using selective adenosine A2A receptor antagonist non-flow-limiting stenoses were graded to reduce hyperemia LAD flow by 30%, 60% and 90% (n=10, NFLS). Graded stenoses reduced resting LAD flow by 25%, 50%, 75% and 100% of baseline flow measured using transit time flowmeter (n=10 FLS). FCI images were analyzed using a digital image processing system (LLS, Ulm, Germany). The impairment of myocardial perfusion was quantified by background-subtracted peak fluorescence intensity (BSFI) and slope of fluorescence intensity (SFI) obtained with FCI and compared to myocardial blood flow (MBF) assessed by FM.
Results: All flow-limited stenoses resulted in an impairment of myocardial perfusion visualized by FCI. During NFLS and FLS normalized BSFI (r=0.92, p<0.0001) as well as SFI (r=0.93, p<0.0001) decreased significantly (p<0.0001) and demonstrated excellent linear correlation with FM-derived MBF. Even a low impairment can be quantified by FCI.
Conclusions: The impairment of myocardial perfusion in response to increased stenoses can be quantitatively assessed by FCI, and correlates good with results obtained by FM.