A method and system for analyzing cardiac periodicity includes a processor, a display device, and a probe. The method and system includes acquiring ultrasound data from cardiac tissue with the probe, generating an m-mode image from the ultrasound data with the processor, displaying the m-mode image on the display device, selecting a portion of the m-mode image exhibiting periodic motion, analyzing the portion of the m-mode image with the processor to determine a cardiac periodicity, and displaying a graphical representation of the cardiac periodicity on the display device.