Real-time three-dimensional echocardiography and 3D-STE
measurements
To acquire 3D echocardiographic LV full volume images, we used a
matrix-array 4V-D probe (1.7-3.3 MHz). In real-time dynamic
three-dimensional pattern, the frame rates of echocardiographic image
were 25-50 frames/s. When the entire LV myocardium, endocardium, and
epicardium were clearly displayed in apical 4-chamber view, we told the
patients to hold their breath after a calm breath in order to eliminate
breathing motion artifacts. Furthermore, to make sure a clear image, it
is necessary to adjust the buttons that control the depth and width of
the probe during the operation. Then turning into 4D full volume
pattern, we continued to collect real-time
dynamic three-dimensional images
of LV in four consecutive cardiac cycles which can be analyzed with
3D-STE. At last, starting 4-dimensional automatic LV quantitative
analysis software (4D-Auto LVQ) to analyze all the collected full-volume
images. This software will automatically delineate the edocardial
boundary of the LV, which can be manually adjusted if required. The
parameters including LV end-diastolic volume (LVEDV), LV end-systolic
volume (LVESV), LV ejection fraction (LVEF) were measured and strain
curves for 17 segments of the LV wall were obtained. Global longitudinal
strain (GLS), global area strain (GAS), global radial strain (GRS) and
global circumferential strain (GCS) of 17 myocardial segments in each
direction were got by computing the weighted average of the peak
systolic strain values. The left atrial intima was traced in the same
way to measure the left atrial maximum volume, and calculated the left
atrial maximum volume index (LAVImax, LAVImax=LAVmax/BAS). Each
parameter was measured three times by a physician, and the average value
was taken.