  How do you use imaging to analyse the development of the heart, which not
only changes shape but also undergoes constant, high-speed, quasi-periodic
changes? We have integrated ideas from prospective and retrospective optical
gating to capture long-term, phase-locked developmental time-lapse videos. In
this paper we demonstrate the success of this approach over a key developmental
time period: heart looping, where large changes in heart shape prevent previous
prospective gating approaches from capturing phase-locked videos. We use the
comparison with other approaches to in vivo heart imaging to highlight the
importance of collecting the most appropriate data for the biological question.
