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 all 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. Each parameter was measured three times
by a physician, and the average value was taken.
We analyzed all data using SPSS 19.0 software (SPSS 19.0, Inc., Chicago,
IL, USA). All data conforming to normal distribution were showed as mean
values±standard deviations. Comparisons of the gender among the three
groups were made by using χ²-test. Differences of more than two groups
were compared by analysis of one-way ANOVA. And we compared the
differences between two groups by using LSD-t test. To obtain the
correlations between 3D-STE parameters and NT-proBNP in three groups, we
used Pearson linear correlation analysis. The values of P<0.05
demonstrated that the results were statistically significance.