1. A method of generating high frame rate composite ultrasound frames, comprising: acquiring a series of ultrasound frames for each of N sectors over a duration of one or more cardiac cycles; substantially simultaneously acquiring an ECG signal for each cardiac cycle, wherein each of said series of ultrasound frames for each sector is triggered or gated using said ECG signal; synchronizing the data for the sectors in time using the ECG signals; combining the data from the various sectors to generate a series of composite ultrasound frames at high frame rate; and displaying at least one of said series of frames to a user.