Fig. 1

Measurement of amplitude and timing of the effective contraction and the total contraction. a illustrates the definition of Strain and the concept of Myocardial Contraction Efficiency which was put forward for the first time in the current study. b Longitudinal myocardial shortening within left ventricular ejection (LV_Ej) and throughout a beat were defined as effective contraction (EC, green line) and maximum longitudinal strain (MLS, amaranth line), respectively. Time spent for EC and MLS were defined as effective contraction time (ECT, blue line) and total contraction time (TCT, red line), respectively. c shows the pulsed-wave Doppler ultrasound in the LV outflow tract. The horizontal axis represents velocity (m/s) and the vertical axis represents time (ms). EKG was used as the reference of cardiac cycle timing (green curve). Timing of aortic valve opening and closure were measured at the beginning and the end of the envelope and LV ejection period was then determined (period between blue lines). d show the longitudinal strain curve by 2D speckle tracking for a healthy control. The Y axis displays longitudinal strain (%) and the X axis displays time according to EKG (ms). The reference line (the left red line) was placed at the beginning of the QRS complex when the longitudinal strain was defined as zero. Aortic valve closure (AVC) and opening (AVO) were defined according to (c). The majority of contraction occurs within LV_Ej in healthy control. AVO: aortic valve opening; AVC: aortic valve closure; LV_Ej: left ventricle ejection period;EC: effective contraction; MLS: maximum longitudinal strain; ECT: effective contraction time; TCT: total contraction time