The Role Of Tissue Doppler Imaging In The Monitoring Of Left Ventricular Function. Surgery

Background: Cardiac function is good predictor of outcome for cardiac surgery patients. Fast assessment and early intervention of left ventricular (LV) function provides an important information on the hemodynamic status and benefits the outcome and prognosis in the cardiac surgery patients. TDI(tissue Doppler imaging) is a new noninvasive technology of assessing movement of myocardium, which is used for evaluation of the cardiac function. However, there is no literatures on correlation between the TDI variables and pulmonary arterial catheter parameters(PAC) reported in cardiac surgery patients. This study is designed to analysis the relationship between the TDI variables and PAC parameters.Objects: This study was to investigate the success rate of TDI and conventional Doppler sampling at different site of heart; to assess whether mitral annular velocities as measured by TDI are associated with invasive measures of PAC parameters and whether additional information is gained over traditional Doppler variables; to investigate the reliability of TDI in estimating left ventricular filling pressure.Methods: We prospectively studied 40 patients, mean age 63±7.8 years, in sinus rhythm. All patients underwent CABG. Transesophageal echocardiography (TEE), pulmonary artery catheterization (PAC) and other hemodynamic monitoring were performed at the same time. PAC investigated continuous cardiac output (CCO), central venous pressure(CVP) and pulmonary capillary wedged pressure(PCWP). TEE-LVEF was calculated using M-mode analysis and vision assessment of wall motion of LV wall. The following Doppler parameters were assessed: PW Doppler signals from the mitral inflow (E, A), PW TDI of the mitral annulus (Sa, Ea, Aa), thus allowing to obtain the mitral inflow to annulus ratio (E/Ea). Correlations were analyzed between EFs,Sa and CO, and between the TDI parameters and PCWP. Then according to the CI＞2.0, patients were divided into 2 subgroups. Correlations were re-analyzed in the subgroups to identify the differences between two groups. ROC analysis was done for the correlated variables to identify the best parameter and cut-off value to predict elevation of PCWP.Results: 1 TDI spectrums could be obtained from septal annulus, lateral annulus, anterior wall and posterior wall of left ventricle. The success rate of sampling from septal annulus, anterior and posterior wall is 100%, while the lateral annulus is 95%(2 cases unsuccessful). Mitral signal is more easly got with success rate of 100% than pulmonary venous signals with success rate of 85%.2. For the systolic function, both annulus contraction velocity in septal and lateral wall are significantly higher(4.7±0.8, and 6.2±2.2) in normal function group than that(3.8±0.763.8±0.76 and 4.5±1.0) in abnormal group(P＜0.05); Septal and lateral contraction velocity correlated well with CO (r=0.606 and 0.438 respectively), and septal contraction velocity correlated with CO in abnormal group(r=0.653, P＜0.01). Both EFs investigated by calculation(r=0.627, P＜0.01) and vision assessment(r=0.626, P＜0.01) correlate well with CO as well.3. Diastolic function: Although transmitral E/A ratio showed a better correlation with PCWP in abnormal group than that in whole patients, ROC analysis showed that it could not predict the PCWP elevation because 0.5 was included in 95% CI. Pulmonary venous velocity curves were not found have close relationship with PCWP in this study. For TDI of mitral annulus movements, early and late velocity ratio(Ea/Aa) at septal and lateral wall show an inverse correlation with PCWP(r=-0.635, and -0.670 respectively). Septal annulus Ea/Aa has a constant relationship with both normal and abnormal group(r=-0.635 and -0.670 repectively). The ratio of mitral velocity to early diastolic velocity of septal mitral annulus E/Ea(r=0.699, P＜0.01), mean E/Ea(r=0.685, P＜0.01),lateral E/Ea (r=0.681, P＜0.01) ) showed a correlation with PCWP, and septal E/Ea间隔(r=0.681vs 0.738), mean E/Ea (r=0.760 vs 0.527,) had better correlation than did other Doppler variables for all levels of systolic function. The ROC analysis was repeated with PCWP＞12 mm Hg used as the definition of elevated filling pressure. The areas under the respective ROC curves were 0.905(septal E/Ea), 0.764(setal Ea/Aa), 0.732 (mean E/Ea ratio).As with the cutoff value of E/Ea＞14 mm Hg, the septal E/Ea and lateral Ea/Aa had the best ROC curve and was the most readily obtained. Septal E/Ea＞14 had 83.33-92.31% sensitivity and 71.43-87.50% specificity for prediction of elevated PCWP. As with cutoff value of septal Ea/Aa＜0.95, Ea/Aa had 60.00-69.23% sensitivity and 57.14-87.50% specificity.Conclusions: 1. High quality of TDI of mitral annulus, anterior and posterior left ventricle can be obtained with TEE. The success rate of sampling is higher at septal annulus, anterior and posterior of left ventricle than that at lateral site. Mitral flow velocity is much easier to get than pulmonary venous flow velocity.2. EFs accessed by calculation and visual estimation are fast and accurate method to evaluate the systolic function. Septal and lateral annulus systolic velocity had a close relationship with the systolic function while anterior and posterior wall systolic velocity did not have.3. Diastolic function: Although mitral flow velocity ratio(E/A) correlated with PCWP, it can not predict the elevated PCWP; The combination of TDI of the septal mitral annulus and mitral inflow velocity curves and septal annulus early and late velocity ratio provide better estimates of LV filling pressures than other parameters.