Estimation Of Left Ventricular Diastolic Function And Filling Pressure In A Rabbit Model By Doppler Echocardiography

ObjectsThe present study was aimed to investigate the relations between parameters of left ventricular diastolic function echocardiographically and invasively in rabbit model of pressure overload-induced left ventricular hypertrophy(LVH), and to explore the value of Doppler echocardiographic Ea and E/Ea in the estimation of left ventricular diastolic function and filling pressure.MethodsAn animal model of pressure overload-induced LVH was established by abdominal aortic coarctation in 18 New-Zealand rabbits(model group) which developed LVH with normal left ventricular ejection fraction(LVEF, >50%) and 8 healthy rabbits served as normal controls. Two dimensional and Doppler echocardiographic measurements were detected before abdominal coarction and 24 hours before invasive examination. Echocardiographic measurements included:(1) Left atrial diameter and volume(LAD, LAV),left ventricular end-diastolic and end-systolic diameter (LVEDD,LVESD),wall thickness(IVST,PWT), relative wall thickness (RWT), LVEF and shortening fraction(FS); (2) Transmitral diastolic early and late peak inflow velocities(E,A), peak systolic velocities(Sa),early and late diastolic velocities(Ea, Aa) of mitral annulus by tissue Doppler, and (3) E/A, Ea/Aa, E/Ea. Invasive parameters included left ventricular end-diastolic pressure(LVEDP) and LV-dp/dtmax. Correlation analysis was undertaken between echocardiographic and invasive parameters. Myocardium was examined by histopathology.Results1.Echocardiographic finding Compared with measurements before abdominal coarctation, increased LVEDd, LVEDs,IVST, PWT, RWT,LAD and LAV were found in model group (P<0.05); Although no significant difference in LVEF and FS, a significant decrease was found in Sa; There were significant decreases in Ea and the ratio of Ea/Aa,increases in the ratio of E/Ea(P<0.05),but no difference in E and E/A was found.2. Invasive Parameters In model group, there was a significant increase in LVEDP and a significant decrease in LV-dp/dtmax compared with control group.3. Linear correlation analyses In model group, significant correlations were found between E/Ea and LVEDP(r=0.54,P<0.05),E/Ea and LAV or LAD(r=0.72 and 0.79,P<0.05); Ea related to IVST and PWT (r=-0.42 and -0.60,P<0.05); and correlations between IVST or PWT and LAV was also noted(r=0.32 and 0.53,respectively,P<0.05).4. Increases in the myocardiocyte size and collagen fraction were found in rabbit model by histopathology.Conclusions1. Doppler echocardiography is an important tool in the evaluation of left ventricular diastolic function. Ea correlates with the degree of left ventricular hypertrophy and active relaxation. E/Ea ratio correlates with LVEDP,and the combination of Ea and E/Ea ratio is useful in the evaluation of diastolic function and filling pressure .2. Left atrial size, which correlates with LVEDP, left ventricular wall thickness and E/Ea, may be an important morphologic index in the estimation of left ventricular diastolic function by combining with other Doppler echocardiography indexes such as Ea and E/Ea..3. Left ventricular long-axis systolic performance is slightly impaired in animal model of pressure overload-induced LVH when detected by Doppler tissue imaging although the global systolic function shows"normal".