| BackgroundLeft ventricular(LV) dilation and geometric changes after acute myocardial infarction(AMI) is defined as left ventricular remodeling. Accurately measurement of LV volume is of major importance for early evaluation, dynamic observation and prognosis of cardiac remodeling after AMI. Therefore, attention has been paid to accurately measurement of LV volume. LV ejection fraction(LVEF) can sensitively reflect the changes in ejection function and systolic function of left ventricle as well as reliably evaluate the efficiency of pumping in left ventricle. Therefore, LVEF is the mainly variable in quantitative evaluation of global systolic function in LV.Left atrial(LA) volume and function are the important regulators of LV diastolic filling, being important as maintaining normal cardiac function. Accurate measurement of LA volume and function has important clinic value. It is helpful to evaluate the changes in LA volume and function for further understanding the information about prognosis on the basis of measuring LV volume and function in patients with AMI.Because of the limitation of Bi-plane LV angiography, magnetic resonance imaging(MRI), two dimensional echocardiography(2DE) and dynamicthree-dimensional echocardiography in measurement of heart chamber volumes, it would be of clinical importance to find an invasive, accurate, simple and repeatable method for measuring LA and LV volumes and evaluating LV remodeling after AMI.New real time three dimensional echocardiography(RT-3DE) has recently become available. The system permits a true three-dimensional assessment of cardiac structure and function and calculation of cardiac chamber volume without geometrical assumption with aid of TomTec volume analysis software. RT-3DE provides a new measurement method for accurately evaluating LV and LA volumes and functions as well as dynamic alterations after AMI. However, the functional ability and clinical feasibility in measuring LV and LA volumes and functions of this system need further study. Aim(1) To evaluate the validation and feasibility of RT-3DE measurement of LV and LA volumes and functions of normal subjects and patients with AMI;(2) To evaluate the difference in methodology of LV and LA volumes and functions measuring between normal subjects and patients with AMI;(3) To study the validation and feasibility of RT-3DE in evaluating cardiac remodeling after AMI. Methods1. Study population. (Dgroup I (control group): thirty subjects(mean age 57+12 years, 21 men and 9 women) served as control subjects. All subjects had no cardiac disease and had normal physical examination, chest roentgenogram, electrocardiogram, as well as echocardiogram. (2)group II: Thirty patients with old myocardial infarction (mean age 60+14 years, 23 men and 7 women) were included.2. Measureing methods. (l)Magnetic resonance imaging. Measuring volumes and functions of left atrium and ventricule. (2)Echocardiography. 2DE examination. Atrial and ventricular volumes and functions were measured with biplane Simpson's method.(3) RT-3DE. Real-time 3DE images were obtained from the apical window. Measurement of RT-3DE volumes were performed off-line with TomTec volume analysis software. Endocardial contours were marked in 2 planes[RT-3DE(2), 90° perplane], 4 planes[RT-3DE(4), 45° per plane], 8 planes[RT-3DE(8), 22.5° per plane] and 16 planes[RT-3DE(16), 11.25° per plane]. The left ventricular end-diastolic volume(LVEDV), left ventricular end-systolic volume(LVESV), stroke volume(SV), left ventricular ejection fraction(LVEF), maxium left atrial volume(LAVmax), minimum left atrial volume(LAVmin), onset atrial emptying volume(OAEV), left atrial ejection fraction(LAEF=LASV/OAEV X 100%)were measured from the resulting three-dimensional volume.3. Statistical analysis. Data analysis were performed using SPSS statistical software(version 10, SPSS Inc., Chicago, Illinois). Results are represented as mean and standard deviation. A /'-value/' <0.05 was considered significant. Correlations were performed between echocardiography and MRI measurements with Pearson method. Differences in measurements between echo and MRI were expressed as mean ± SD. Agreement analysis between methods was performed according to the technique of Bland and Altman. Results:1. LV volume and function variables in group I2DE and RT-3DE(2) underestimated LVEDV, LVESV and SV significantly compared with MRI. LVEDV, LVESV and SV obtained by RT-3DE(4), RT-3DE(8), RT-3DE(16) were also lower than those obtained by MRI but the differences were not significant. LVEDV, LVESV, SV, EF by MRI had higher correlations with those by RT-3DE(4), RT-3DE(8), RT-3DE(16) than with those by RT-3DE(2), 2DE.There were greater differences between LVEDV, LVESV, SV, EF by 2DE, RT-3DE(2) and those by MRI. Also, there were wider limits of agreement between LVEDV, LVESV, SV, EFby2DE, RT-3DE(2) and those by MRI.2. LV volume and function variables in group II2DE, RT-3DE(2), RT-3DE(4) underestimated LVEDV , LVESV and SV significantly compared with MRI. LVEDV, LVESV and SV obtained by RT-3DE(8), RT-3DE(16), were also lower than those obtained by MRI but the differences were not significant. LVEDV, LVESV, SV, EF by MRI had higher correlations with those by RT-3DE(8), RT-3DE(16) than with those by RT-3DE(4) , RT-3DE(2), 2DE. Therewere greater differences between LVEDV, LVESV, SV> EF by 2DE> RT-3DE(2), RT-3DE(4) and those by MRI. Also, there were wider limits of agreement between LVEDV, LVESV, SV^ EFby2DE> RT-3DE(2), RT-3DE(4) and those by MRI. 3. LA volume and function variables in group I and group II In group I and group II, 2DE, RT-3DE(2), RT-3DE(4) underestimated LAVmax^ LAVmin and OAEV significantly compared with MRI. LAVmaxs LAVmin and OAEV obtained by RT-3DE(8), RT-3DE(16) were also lower than those obtained by MRI but the differences were not significant. LAVmax> LAVmin, OAEV and LAEF by MRI had higher correlations with those by RT-3DE(8), RT-3DE(16) than with those by RT-3DE(4), RT-3DE(2), 2DE.There were greater differences between LAVmax> LAVmin, OAEV, LAEF by 2DE, RT-3DE(2), RT-3DE(4) and those by MRI. Also, there were wider limits of agreement between LAVmax^ LAVmin, OAEV, LAEF by 2DE> RT-3DE(2), RT-3DE(4) and those by MRI. Conclusions1. RT-3DE is accurate and reliable for the quantitative assessment of left atrial and ventricular volumes and functions. There were good correlation and agreement between left atrial and ventricular variables obtained by RT-3DE and those by MRI.2. The accuracy of RT-3DE in measuring left atrial and ventricular volumes has a close relation with the number of image planes in processing data. It is accurate as well as efficient to measure LV volumes in control group with RT-3DE(4) and it is accurate as well as efficient to measure LV volumes in patients with OMI and LA volumes both in control group and in patient group with RT-3DE(8),3. RT-3DE provides a new measurement for accurately evaluating cardiac remodeling after AMI.
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