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Figure 2 (A) Sample of the echocardiographic measurements. (B) Representative patterns of transmitral Doppler flow during AV sequential pacing with the optimal AV delays. White bars indicate the atrial pacing spike. (a) High right atrial (HRA) pacing; (b) Coronary sinus (CS) pacing; (c) Bi-atrial (BiA) pacing. The BiA pacing produced the most increased peak velocity of the atrial filling wave (A Vmax) and the shortest interval from the atrial pacing spike on the electrocardiogram to the peak of the atrial filling wave (S-A peak). E Vmax = peak velocity of the early filling wave; TVI = mitral flow time velocity integral; other abbreviations as in Figure 1.