Although fluorescence microscopy has opened up new avenues for developmental imaging, the heart remains a particularly challenging organ to image in 3D timelapse. To image processes on timescales of minutes to hours (such as heart development, cell migration, repair and regeneration) demands some form of synchronized image acquisition in order to separate the high-frequency heartbeat motion from the lower-speed morphological changes of interest. We have combined image processing with optics to develop prospective optically-gated light sheet microscopy that allows synchronised 3D imaging of the in vivo beating zebrafish heart. However, sustained timelapse imaging over 24h or more presents significant additional challenges, since the dramatic morphological changes undergone by the heart frustrate existing synchronization approaches. I will describe how we have been able to overcome this barrier by using adaptive prospective optical gating technologies, and present 24h 3D-timelapse video imaging of cardiac development and immune response to cardiac injury.