Analysis by VFM
Optimized two-dimensional ultrasound color movies of the apical three-chamber view were transferred to a computer with the VFM software DAS-RS1 (Hitachi Ltd., Tokyo, Japan). Each image of one cardiac cycle was selected using electrocardiography. All aliasing phenomena were checked, and the aliasing area was manually corrected. The LV endocardial boundary was initially traced manually and was then traced automatically throughout the remaining frames. The software used calculated intracardiac EL in one cardiac cycle from VFM images.
By echocardiography and electrocardiography, one cardiac cycle was separated into the following three phases: ED, LD and Sys. ED was defined as the phase from the opening of the mitral valve to before the start of atrial contraction. LD was defined as the phase from the start of atrial contraction to the closing of the mitral valve. Peak EL in each phase was collected as a parameter. An example of the VFM analysis in the present study is shown in Figure 1.