An ultrasound imaging system performs spectral Doppler processing in a manner that considers a physiological cycle of a subject. In one embodiment, gaps in a spectral Doppler signal are filled taking by a processor that analyzes changes in the spectral Doppler signal caused by a physiological cycle. Spectral Doppler data are scaled to fit with the data occurring before and after a gap. The firing order of an interleaved imaging mode can also be adjusted so that spectral Doppler imaging is not interrupted during pre-defined or user defined portions of a physiological cycle.
