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Figure 4 (A and B) Show pulsed-wave Doppler recordings of the left ventricular inflow mathematically adjusted for the difference in heart rate between the two pacing modes. Note the significantly prolonged mitral inflow time and the more physiological E and A traces in the VDD mode (B). In the DDD mode, there is incomplete fusion between E-wave (passive mitral inflow) and A-wave (active atrial filling). Note that there is a beginning cutoff of the A-wave in the DDD mode, although there is a lower degree of left ventricular synchronization compared to VDD pacing as suggested by the mitral flow impairment (see text).