Study On Right Ventricular Dyssynchrony In Patients With Pulmonary Hypertension Using Tissue Doppler Strain Imaging

Objective:1 To provide another valuable approach in detecting right ventrichlar function using echocardiography by the study on RV dyssynchrony in patients with PH.2 To determine whether right ventricular dyssynchrony is present in patients with pulmonary hypertension (PH) using longitudinal strain imaging, and analyze the correlation of RV dyssynchrony strain parameters with right ventricular(RV) function parameters and structure parameters in order to provide a valuable parameter for clinical evaluation of right ventricular function.Methods:1 The study population consisted of 60 patients with PH (patient group, male 21 and famale 39), in all, 9 patients with primary pulmonary hypertension, 12 patients with congenital heart disease, 11 patients with chronic thrombembolic, 13 patients with chronic obstructive pulmonary disease, 15 patients with connectibe tissue disorder. The PH patients divided into 3 groups based on the values of pulmonary artery Systolic pressure(PASP), each group contained 20 patients. Group A is mild PH Patients (30mmHg≤PASP<50mmHg,1mmHg=0.133kPa) , 7 males and 13 females , mean age of 41.12±15.38 years; group B is medium PH patients (50mmHg≤PASP<70mmHg), 8 males and 12 females , mean age of44.20±15.85 years; group C is severe PH patients (PASP≥70mmHg ), 6 males and 14 females,mean age of 41.00±13.03 years. Patients with right ventricular outflow obstruction, right bundle-branch block, acute myocardial infarction, valvular heart disease, cardiomyopathy, severe arrhythmia, the presence of pacer in the right ventricle and abnormal LV systolic function were excluded from the analysis. The control group consisted of 20 age- and gender- matchde normal volunteers(8 males and 12 females, mean age of 41.25±13.12 years).2 A color Doppler ultrasonic systen(GE Vivid7) and 1.5-4.0MHz transducer was used with an Echopac workstation.3 All echocardiography studies were performed with the subjects lying in the left lateral decubitus position in connection with electrocardiogram. All the date were recorded in 3 continuous beats and were stored in hardware for off-line analysis in Echo Pac. All eochcardiogrophic parameters were measured and calculated by a single operator.4 Image analysis and parameter measurement:4.1 Pulmonary artery systolic pressures were estimated by calculating the systolic pressure gradient between the right ventricle and right atrium by the maximum velocity of the tricuspid regurgitant jet using the modified Bernoulli equation, and then adding to this gradient an estimated right atrial pressure based on the size of the inferior vena cava and its variation with respiration.4.2 We measured right atrial diameter(RATD). Right ventricular end-diastolic and end-systolic areas (RVEDA, RVESA) were measured, RV fractional area change(RVFAC)= [(RVEDA–RVESA)/RVEDA]×100%(RV global systolic function parameter). RV diameter(RVTD) and LV diameter(LVTD) were measured and the ratio of RVTD/LVTD(RV structure parameter) were calculated. All the data mentioned above were obtained in the apical 4-chamber view.Obtaining tissue velocity curve of tricuspid annulus of RV lateral wall in the apical 4-chamber view, we measured early diastolic velocity(Ea) , late diastolic velocity(Aa) and calculated the rate of Ea/Aa(RV diastolic function parameter), as same as, we measured the time from Aa finishing to onset next Ea(a) and the time of the Sa lasting(b), calculating Tei-index according the equation: Tei-index=(a-b)/b.4.3 Reference to the segment model for the RV wall that introduced by D'Arcy et al, RV walls were divided to free wall, posterior wall, interventricular septum and anterior wall along long-axis, each of the wall was further divided to 3 segments (the basal , the moderate and apex-ventricular). We obtained tissue doppler image of the apical 4-chamber view and RV right ventricular outflow long-axis view, regions of interest were placed in the basal and mid-ventricular segments of the right ventricular free wall, interventricular septum, and posterior wall(becouse of unsharp image of RV anterior wall and the angular dependence of apex-ventricular segment, the segments mentioned above were excluded). Obtaining strain curve of 6 segments, we measured the peak longitudinal systolic strain(PST) and the time to peak strain(TQ-S, the time from onset of QRS complexes to Sa) of each segment, calculated the maximal difference of TQ-S(Max-ΔTQ-S, RV dyssynchrony parameter) and PST(Max-ΔPST) in all 6 segments. All parameters velue were averaged from 3 beats.Results:1 Comparison of general parameters There were no differences between the groups in age and sex(P>0.05).Control group had slower heart rate than group A, but this not reach statistical significance(p>0.05), but, the difference had statistical significance(P<0.05) in each of PH groups, the more severe PH, the faster heart rate. RATD in control group compared with group A, no difference was found(p>0.05), but group B and group C were significance larger than control group(p<0.05).2 Comparison of RV parametersPASP progressive increased in control group, group A ,group B and group C, the difference of each group had statistical significance(P<0.01). PH groups had greater RVEDA, RVESA, RATD, RVTD/LVTD and Tei-index than control group, but ,it do not reach statistical significance between group A and control group(p>0.05), the parameters mentioned above in group B and group C were significance larger than control group(p<0.05), expect that RVTD/LVTD only in group C were significance larger than control group(p<0.05). PH groups had smaller RVFAC,Ea,Ea /Aa compared with control group, the difference had no statistical significance between control group and group A(p>0.05), but , there were significant difference in control group compaired with group B and group C.Compared with control group, PH groups had significantly larger Max-△PST and Max-△TQ-S(p<0.01); in PH groups, the difference of Max-△PST had no statistical significance(p>0.05); Max-△TQ-S had no statistical significance(p>0.05) between group B and group C.3 Correlation analysis of RV strain parameters with RV structure and function parameters3.1 Max-△TQ-S had strong correlation with PASP(r=0.81; P < 0.001). Max-△TQ-S had better correlation with RVESA, RVFAC , RVAD/LVTD, Tei-index and Ea ( r=0.62, p<0.001; r=-0.71, p<0.001; r=0.71, p<0.001; r=0.68, p<0.001;r=-0.66,p<0.001, respectively), it had good correlation with RVEDA , RATD and Ea /Aa (r=0.44,p<0.01;r=0.48, p<0.01;r=-0.48, p<0.01, respectively).3.2 Max-△PST had good correlation with PASP(r=0.48, p<0.01), it had some correlation with Tei-index, Ea and Ea /Aa (r=0.41, p<0.05;r=-0.45, p<0.05;r=-0.42,p<0.05, respectively).Conclusion:1 Strain imaging as a new ultrasound technology, which temporal and spatial resolution are both high, can accurately reflected the regional myocardial systolic activities, recognite the nuances in different segments of myocardial deformation in space and time distribution. Strain imaging is a valuable method detecting RV function by echocardiogrophy.2 Patients with PH exhibit right ventricular dyssynchrony,and has signifisently difference in mild PH group. RV dyssynchrony parameter has the following advantages,such as sensitive, curve smoothing, easy to measure, not be affected by cardiac geometry, having good correlation with right ventricular function and structure parameters,et al. We think right ventricular dyssynchrony parameter could evaluate right ventricular function in PH patients earlier.