Near-infrared Fluorescence Coronary Angiography: a New Noninvasive Technology for Intraoperative Graft Patency Control

Background: Intraoperative graft patency verification is of major clinical importance for quality control after coronary artery bypass grafting (CABG), especially if surgery is performed on the beating heart. This is one of the first reports of fluorescence coronary angiography (FCA) using the dye indocyanine green (ICG), a noninvasive technology for direct visualization of coronary arteries, bypass grafts, and myocardial perfusion.

Methods: Twenty-three domestic pigs (weight, 45-72 kg) underwent FCA of the left anterior descending coronary artery (LAD). In the first group (n = 6 pigs), FCA was used to visualize the native coronary vessels and myocardial perfusion. In the second group (n = 8 pigs), 14 stenoses of various degrees and 4 total vessel occlusions were created by snares on different segments of the LAD, and FCA was used to visualize the effects of these obstructions. In the third group (n = 9 pigs), a coronary bypass procedure on the beating heart was performed by a left internal mammary artery or a human saphenous vein graft to the LAD, and FCA was used to visualize graft patency. Three pigs were removed from the study because of ventricular fibrillation. ICG was intravenously applied, and the heart was illuminated with near-infrared light emitted by laser diodes. The fluorescence emission was detected by an adapted charge-coupled device camera system. The images were displayed in real time on a high-resolution monitor. Subsequently, images obtained with FCA were compared to those obtained with coronary angiography (n = 10 pigs).

Results: In all cases, high-quality FCA images of coronary arteries and myocardial perfusion were obtained. All stenoses resulted in an impairment of the myocardial perfusion visualized by FCA. Occlusion of the LAD or the diagonal branch resulted in a total perfusion defect of the corresponding anterior myocardial wall with immediate reperfusion after releasing the snare. In 5 cases a patent bypass graft with an apparent homogenous perfusion of the corresponding myocardium was detectable. In one procedure, FCA images indicated total occlusion of the bypass graft and a total perfusion deficit in the distal LAD region. Correlation between FCA and coronary angiography in detection of stenoses and graft patency was excellent.

Conclusion: With the fluorescence technique using ICG, visualization of blood flow in coronary vessels and bypass grafts, as well as of myocardial perfusion, is feasible. FCA is a highly sensitive and reproducible method and an excellent technique for intraoperative quality control in CABG.