In vivo and 3D visualization of coronary artery development by optical coherence tomography

One of the most critical but poorly understood processes during cardiovascular development is the establishment of a functioning coronary artery (CA) system. Due to the lack of suitable imaging technologies, it is currently impossible to visualize this complex dynamic process on living human embryos. Furthermore, due to methodological limitations, this intriguing process has not been unveiled in living animal embryos, too. We present here, to the best of our knowledge, the first in vivo images of developing CAs obtained from the hearts of chick embryos grown in shell-less cultures. The in vivo images were generated by optical coherence tomography (OCT). The OCT system used in this study is a mobile fiber-based time-domain real-time OCT system operating with a center wavelength of 1330 nm, an A-scan rate of 4 kHz, and a typical frame rate of 8 frames/s. The axial resolution is 17 mu m (in tissue), and the lateral resolution is 30 mu m. The OCT system is optimized for in vivo chick heart visualization and enables OCT movie recording with 8 frames/s, full-automatic 3D OCT scanning, and blood flow visualization, i.e., Doppler OCT imaging. Using this OCT system, we generated in vivo OCT recordings of chick embryo hearts to study the process of connection of the future right coronary artery (RCA) to the aorta. Recordings were made at three critical stages during development: day 8 (no clear connection yet), day 9 (established connection of RCA with the aorta with clear blood flow) and day 10 (further remodeling of the established RCA).