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Figure 1 Effect of asynchronous ventricular activation on left ventricular (LV) pressure (upper tracing) and regional strain (lower tracings). During ventricular pacing, strain in different regions becomes asynchronous, as can be judged from the difference in onset of shortening (negative deflection of the curve). Asynchronous contraction causes reduction in ejection time and slows rates of increase and decrease of LV pressure and increases duration of isovolumic contraction (ic) and isovolumic relaxation (ir).