Pulsed wave Doppler tracings of transaortic (AV), transpulmonary (PV), and transmitral (MV) flow from one patient during intrinsic LBBB and during optimized CRT. Optimal mode in this case: biventricular pacing with 90 ms sensed AV delay. Reduction in LVPEI (195–153 ms), IVD (73 ms to −11 ms), and MPI (0.53–0.48), and prolongation of FTc (0.48–0.51), and RVPEI (122–164 ms). Note also the reduced mitral regurgitation signal with CRTopt. CRTopt, cardiac resynchronization therapy with optimal settings.