Fluorescent Cardiac Imaging

Abstract

Background-The purpose of the present study was to examine whether the effect of coronary stenoses of variable severity on myocardial perfusion can be quantitatively assessed in vivo by analysis of fluorescent cardiac imaging (FCI) compared with the gold standard, the fluorescent microsphere method. FCI is a novel technology to visualize coronary vessels and myocardial perfusion intraoperatively using the indocyanine green dye with an infrared-sensitive imaging device. Methods and Results-Graded stenoses and total vessel occlusion of the left anterior descending coronary artery were created in 11 open-chest pigs. Stenoses were graded to reduce resting left anterior descending coronary artery flow by 25%, 50%, 75%, and 100% of baseline flow measured by transit-time flowmeter. FCI images were analyzed with a digital image processing system. The impairment of myocardial perfusion was quantified by background-subtracted peak fluorescence intensity and slope of fluorescence intensity obtained with FCI and compared with myocardial blood flow assessed by fluorescent microsphere. All stenoses resulted in an impairment of myocardial perfusion visualized by FCI. Occlusion of the left anterior descending coronary artery resulted in a total perfusion defect (no fluorescence intensity) of the corresponding anterior myocardial wall. During graded stenosis and total vessel occlusion, normalized background-subtracted peak fluorescence intensity and slope of fluorescence intensity decreased significantly (PϽ0.0001). Both background-subtracted peak fluorescence intensity (rϭ0. Clinical Perspective p 1014At present, there are several technologies to assess intraoperative bypass function, including intraoperative coronary angiography, thermal coronary angiography, ultrasound transit-time flow measurement (TTFM), and high-frequency epicardial echocardiography. However, all these techniques have limitations such as invasivity, misinterpretation, or poor resolution, and the clinical impact of most of these methods remains an unsolved issue. 2,3 Recently, we described the value of a novel, indocyanine green (ICG) -based imaging system (LLS GmbH, Ulm, Germany) for intraoperative visualization of blood flow in 4 -6 Thus, indirect parameters to detect anastomotic stenoses were evaluated in the present study. Our group has previously shown that this technique also allows the visualization of myocardial perfusion, providing further information with respect to the blood supply to the corresponding myocardium. 8 Visualized by fluorescent cardiac imaging (FCI), coronary stenoses resulted in an impairment of myocardial perfusion, and vessel occlusion resulted in a total perfusion defect of the corresponding myocardial region. 4 Although high-quality images of myocardial perfusion were obtained by FCI, quantitative assessment of myocardial perfusion deficits was not yet possible. 4 The aims of the present study were to quantitatively assess the effect of different coronary stenoses on myocardial perfusion by analysis of FCI and to compare the...

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