Abstract
In echocardiography, various indices are obtained to assess cardiac function. Although these indices should be measured in the images of the same heartbeat, practically, they are measured on different heartbeats on the assumption that the R-R interval of the electrocardiogram is substantially constant. Dual Gate Doppler technique enables us to observe Pulsed Doppler waveform on the different two positions, so it is useful not only for sinus rhythm but also for atrial fibrillation patients. There are two types of Pulsed Doppler, blood flow waveform acquisition and tissue motion waveform acquisition. Dual Gate Doppler can be used in arbitrary combination of two types of Pulsed Doppler. However, it is concerned that by transmitting the beam in two directions, the upper limit of the velocity range is reduced in comparison with the conventional one direction Doppler. Typically, the velocity required for the PW mode is 1.0～1.5m/s.In order to solve this problem, the PRT and the velocity range of the transmission in two sample volumes are constantly optimized. As a result, we have realized a sufficient velocity range for observing blood flow in echocardiography.
