| Objective: To assess the function and the change of blood flow of left atrial appendage(LAA) in patients with atrial fibrillation using two-dimensional speckle tracking transesophageal echocardiography(2D-TEE)and M-mode color Doppler,and predict the risk of thrombus in LAA.Method:1 Seventy-three patients with AF were enrolled experimental group then all patients were corresponded to diagnosis of AF guide line,which was enacted by European Society of Cardiology(ESC) in 2010.The patients were divided into two group by the presence of thrombus in LAA:(1)patients had thrombus in LAA(n=29,male 19,female10,mean age of 62±8years),(2)patients had no thrombus in LAA(n=44,male 26,femal 18,mean age of 63±7years).We selected 20 healthy volunteers who were matched age and gender with atrial fibrillation patients to serve as controls(n=20,male13,female7,mean age of61±9years).The volunteers had no related medical history,physical examination,ultrasound echocardiography,electrocardiogram(ECG) and laboratory tests showed no abnormality.2 A commercially available Philips i E33 ultrasound machine(PHILIPS Healthcare) was employed,with a probe of X7-2t.QLAB CMQ workstation was available for quantitative analysis of 2D-STEE.3 Before TEE,patients should make preoperative examination and fast for solids and liquids at least 4-6h,and sign a consent form,and then take two 2%Lidocaine Hydrochloride Jelly orally for pharynx mucosal local anesthetic.The patients should lie left position and were connected with ECG.We recorded the data,such as gender,age,and heart rate(HR).4 Parameters measurement and image analysis: 1) Parameters of the two-dimentional transthoracic echocardiography was measured :left atrium diameter(LAD),LVEF,diastolic e-wave(e') and left ventricular filling pressure(E/e').Examiner took the X7-2t probe,which was a high frequency probe, insert into the esophagus and in the middle esophagus rodating the transducer angle to between 60°and 90°would generate the long axis of the LAA.Then we adjusted the Gain in order to get the image to display cleanly and four consecutive heart cycles were recorded with stable ECG recording and stored for on-line analysis.Below LAA parameters all was measured in the long axis of the LAA;2) Parameters of the two-dimentional transesophageal echocardiography To measure LAA two-dimentinal parameters,we took the dynamic image.In the end-diastolic,we measured the maximum width of the orifice of the LAA and the maximum length form the middle of the orifice to the tip.Then,in the end-diastolic and end-systole we traced left atrial appendage endocardial for the maximum area of the LAA(LAAmax) and minimum area of the LAA(LAAmin) respectively.We can calculate the left atrial appendage area change percentage(LAA-EF).LAAmax was divided by a difference,which was gained by LAAmax minusing LAAmin, to get LAA-EF.The pulsed Doppler sample volume was typically placed 1 to 2 cm from the orifice within the chamber. During atrial fibrillation,we measured LAA maximum positive wave and maximum negative wave serve as LAA emptying velocity(LAA-EV) and filling velocity(LAA-FV) respectively.During sinus rhythm,we measured LAA maximum positive wave(followed closely by P wave in the ECG) and LAA maximum negative wave(followed closely by P wave in the ECG) serve as LAA emptying velocity and filling velocity respectively. Under the color Dopplor M-mode echocardiography measured left atrial appendage flow propagation velocity(LAA-FPV).According to slope of the blood first mixing in the LAA,we can measure LAA-FPV;3) Image acquisition of Speckle Tracking Echocardiography and image analysis : Two-dimensional echocardiography images were analysed using QLAB CMQ. The STE analysis was performed online by single operator to avoid interobserver variability. During atrial fibrillation patients,LAA endocardial border was manually traced in the LAA long axis plane when LAA under dilaed conditions. During sinus rhythm volunteers,LAA endocardial border was manually traced in the LAA long axis plane when the LAA was in end-diastolic state(before the P wave in the ECG). The software automatically generated a region of intrest(ROI) comsing by six segments. If tracking of the LAA endocardium was ungratified,manual adjustments of the shape and width of ROI were performed to acquire optimal tracking. As preciously described,LAA peak longitudinal strain(LAA PLS),measured at the end of the reservoir phase,was calculated by averaging values observed in all LAA segments(global LAA PLS). LAA strain rate(SR) was measured by quantifying LAA endocardial velocities of contraction and relaxation and local deformation.Sysole srain rate(Ssr) was measured by negative peak wave from SR curve and diastole srain rate(Dsr)was measured by positive peak wave from SR curve.Results:1 Comparision of general clinical parameters between controls and patients with atrial fibrillation.Gender and age did not significantly differ between controls and AF patients(P>0.05). Heart rate was significantly faster in AF patients whose LAA had thumbus than in controls(P<0.05),but there was no difference in the heart rate between AF patients with thrombus and AF patients with no thrombus(P>0.05).2 Comparison of echocardiographic characteristics between healthy controls and patients with atrial fibrillation.When compared with control subjects, LAAL,e'and LVEF were no significant differences in atrial fibrillation patients(P>0.05). LAAW,LA diameter(LAD), E/e'(left ventricular filling pressure)and LAAmin,LAA-EF,LAA-EV,LAA-FV,LAA-FPV in atrial fibrillation patients had significantly diffences with controls(P<0.01).LAA-EV,LAA-FV,LAA-EF,LAA-FPV in atrial fibrillation patients, who had thrombus in LAA,were lower than atrial fibrillation patients who had no thrombus and controls.LAAW,E/e' in atrial fibrillation patients showed greater than atrial fibrillation patients who had no thrombus and controls.LAA-FPV in atrial frillation whose LAA with no thrombus were showed lower than controls(P<0.01). But LAAW,LAA-EF,LAA-EV,LAA-FV,E/e',LA diameter were similar between atrial frillation patients who had no thrombus and controls(P>0.05).In ROC analysis,LAA-FPV had a sensitivity of 85.7% and the specificity of 82.8%(AUC0.869) in predicting functional status with a cut-off was55.4cm/s.3 Comparison of 2D-STE analysis between healthy controls and patients with atrial fibrillation.LAA PLS,Ssr were significantly lower in AF patients than in controls,and in AF patients who had thrombus were the lowest( P<0.01).In atrail fibrillation patierts with thrombus,Dsr was lower than atrail fibrillation patierts with no thrombus and controls.But there was no significantly differences between atrail fibrillation patierts with no thrombus and controls.In ROC analysis, LAA PLS had a sensitivity of 81.3% and the specificity of 93.1%(AUC0.953) in predicting functional status with a cut-off was 20.5%.Ssr had a sensitivity of 75% and the specificity of 82.8%(AUC0.809) in predicting functional status with a cut-off was 2.80-1.4 Correlations between LAA PLS and LAA-FPV and other clinical parameters LAAPLS was significantly positive correlated with LAA-FPV,LAA-EF(P<0.01) and positive correlated with LAA-EV,LAA-FV(P<0.01);LAAPLS was significantly negative correlated with LAAW, LAAL, E/e', LAD(P<0.05).LAA-FPV was positive correlated with LAA-EF, LAA-EV,LAA-FV(P<0.01)and negative correlated with LAD(P<0.01).5 Logistic regression analysis We used Logistic regression analysis to screen the more important risk factors of LAA thrombus in atrail fibrillation patients. We got the conclusion that LAA PLS and LAA-FPV were significant determinants of thrombus (P<0.05).The regression equation was logit P=-6.310+0.227 LAA PLS+0.038LAA-FPV.Conclusion:1 LAA shape:In atrial fibrillation patients, the risk increased with the increasing of the width of the orifice of LAA.2 LAA blood:In artial fibrillation patients,the risk increased with the decreasing of LAA-EV,LAA-FV and LAA-FPV.3 LAA peak longitudinal strain: In artial fibrillation patients,the risk increased with the decreasing of LAA PLS.4 Speckle tracking echocardiography and M-mode color dopplor are more specific and unbiased diagnostic test for evaluating LAA functions with the mono-faceted procedures. |
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