How does the davinci robot do cardiac bypass without opening the chest?

Keyholes: The system uses small, precisely located incisions commonly referred to as keyhole incisions to gain access to the various cardiac structures. The magnifying capability coupled with the extremely small instrument size allow these surgeries to be accomplished without a traditional sternotomy.

No: The operation is done by the surgeon, not the robot. And you need to open the thorax using small incisions.