Researchers are using OCT to capture video of the embryonic heart before it begins beating.  Whereas ultrasound uses sound waves to create viewable, yet grainy, video images, OCT uses optical contrast and infrared broadband laser sources to help generate a real-time, high-resolution output.

Additional general information:

1. The Embryonic Heart: Imaging Life as it Happens - University of Houston Professor Captures Video of Heart Before it Begins to Beat (Video Snippet)
2. A 3D Video of the Embryonic Heartbeat:  Researchers are using a new imaging technique to study the development of the mammalian heart

System to image embryonic heart.

Detailed view of developing heart.

Another detailed view of developing heart.