Fig. 3

Quantitative analysis (to compare with the results of analysis represented in Fig. 7) by echo-particle imaging velocimetry of the orientation angle (φ) of the global hemodynamic forces exchanged between blood and surrounding tissues during acute study (post-cardiac resynchronization therapy 13-day follow-up). Left: Two-dimensional transthoracic echocardiogram high-temporal resolution contrast echocardiographies are performed by three-chamber apical view approach during acute study of different setting (a, b, c, d). Right: Changes in electrical activation settings modify the orientation of intraventricular forces during acute study. The intraventricular forces were predominantly transverse and not aligned along the LVaxis (a₁) as quantified by the large value of their mean angle φ (φ = 55.6°). A first setting option (CRT ON, VV delay 0 ms) changed the orientation of intraventricular forces (b₁) reducing the angle (φ = 45°), and increasing the delay (CRT ON, VV delay − 30 ms) improved the alignment (c₁) reducing the angle (φ = 40.3°). The sequential biventricular activation with delay − 50 ms (d₁) provided the best alignment of intraventricular forces (φ = 38.8°). CRT cardiac resynchronization therapy, F.U. follow-up, PIV particle imaging velocimetry, VV interventricular, TTE transthoracic echocardiogram