A novel fluorescent cardiac imaging system for preclinical intraoperative angiography

Sara Mashalchi,Sara Pahlavan,Marjaneh Hejazi

doi:10.1186/s12880-021-00562-y

Abstract

BackgroundIntraoperative coronary angiography can tremendously reduce early coronary bypass graft failures. Fluorescent cardiac imaging provides an advanced method for intraoperative observation and real-time quantitation of blood flow with high resolution.MethodsWe devised a system comprised of an LED light source, special filters, lenses and a detector for preclinical coronary artery angiography. The optical setup was implemented by using two achromatic doublet lenses, two positive meniscus lenses, a band-pass filter, a pinhole and a CCD sensor. The setup was optimized by Zemax software. Optical design was further challenged to obtain more parallel light beams, less diffusion and higher resolutions to levels as small as arterioles. Ex vivo rat hearts were prepared and coronary arteries were retrogradely perfused by indocyanine green (ICG). Video angiography was employed to assess blood flow and plot time-dependent fluorescence intensity curve (TIC). Quantitation of blood flow was performed by calculating either the gradient of TIC or area under curve. The correlation between blood flow and each calculated parameters was assessed and used to evaluate the quality of flow.ResultsHigh-resolution images of flow in coronary arteries were obtained as precise as 62 µm vessel diameter, by our custom-made ICG angiography system. The gradient of TIC was 3.4–6.3 s−1, while the area under curve indicated 712–1282 s values which ultimately gained correlation coefficients of 0.9938 and 0.9951 with relative blood flow, respectively.ConclusionThe present ICG angiography system may facilitate evaluation of blood flow in animal studies of myocardial infarction and coronary artery grafts intraoperatively.

Highlights

Intraoperative coronary angiography can tremendously reduce early coronary bypass graft failures
We developed an fluorescent cardiac imaging (FCI) system for visualization and assessment of coronary artery blood flow in preclinical models, as a basis for development of intraoperative coronary angiography; our compact design included four-lenses, a band-pass filter and a detector, and resulted in high-resolution imaging of coronary artery flow
Aspherical lens uniformed the incident light In our in-house built FCI system, we used an aspherical lens in order to achieve uniform illumination

Summary

Introduction

Intraoperative coronary angiography can tremendously reduce early coronary bypass graft failures. FCI offers a noninvasive, high-resolution and quantitative system for coronary vessel visualization, and intraoperative assessment of bypass grafts and myocardial perfusion [6,7,8]. Detter and colleagues could successfully enhance FCI efficacy by combining quantitative assessments of myocardial perfusion and FCI imaging for evaluation of graded coronary stenoses, indirectly identifying the bypass graft success [8]. They developed a quantitative system for validation of FCI by differentiating between flow-limiting and non-flow limiting coronary stenosis, to indirectly predict the success rate of bypass surgery [10]. A high correlation between relative blood flow and time-dependent fluorescence intensity curve-associated parameters, was obtained

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Conclusion