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Figure 3 Blood flow and tissue Doppler echocardiographic measurements of heart cycle intervals and systolic left ventricular synchrony (LVS). a = interval between onset of the QRS complex and cessation of left ventricular/right ventricular outflow; b = interval between onset of the QRS complex and start of AV inflow; c = interval between stop and start of AV inflow; d = part of the ejection phase with tissue velocities >0.5 cm/s. CL, PET, ET, a, b, c, and d were directly measured. The other parameters were calculated using the following formulae: IVRT = b – a; IVCT = c – IVRT – ET; DFT = CL – c; Tei index = (c – ET)/ET; Z-ratio = 100 x (DFT + ET)/CL; LVS = 100 x (d/ET). AV = atrioventricular; CL = cycle length; DFT = diastolic filling time; ET = ejection time; IVCT = isovolumic contraction time; IVRT = isovolumic relaxation time; PET = pre-ejection time interval between onset of the QRS complex and onset of left or right ventricular outflow.
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