Evaluation Of Left Ventricular Systolic Function In Patients With Atrial Septal Defects Before And After The Transcatheter Closure By Two-dimensional Speckle Tracking Imaging

【Objective】The atrial septal defect(ASD) is one of the most common congenital heart diseases. Left atrial(LA) shunt to the right atrium(RA) can lead to overload of the right ventricle(RV) and right atrium(RA) capacity. Left ventricular(LV) systolic function reduces because of the pressure of RV. Severe cases may deteriorate to heart failure, and even death. In recent years, with the development of minimally invasive surgery,percutaneous interventional closure was regarded as the preferred clinical treatment because of its smaller wound, quicker recovery, shorter hospitalization, and fewer complications.Two-dimensional Speckle Tracking Imaging(2D-STI) is a novel technology that not only quantitatively can analyze the myocardial velocity, strain and strain rate but also the LV torsion. STI is regarded as a comprehensive quantitative evaluation of overall and regional LV myocardial systolic function.The purpose of this study was to evaluate the variation in LV systolic function in patients with ASD before and after the transcatheter closure.【Methods】Thirty patients with ASD as a patient group(ASD) and 30 healthy volunteersas a control group(NC)were enrolled. The images were recorded at before, 2 days and 6months after the transcatheter closure. The size of the RV, RA and LV by two-dimensional echocardiography were obtained, and the left ventricular end-diastolic volume(LVEDV)and end-systolic volume(LVESV), left ventricular stroke volume(LVSV), and left ventricular ejection fraction(LVEF) were calculated by biplane modified Simpson method.Part 1: Quantitative evaluation of the changes of LV short axial strain in patients with ASD before and after transcatheter closure by 2D-STIDynamic two-dimensional gray-scale images of LV short axis at three different levels(basal level, middle level and apical level) were imported into Echo PAC workstation and analyzed. The images of LV short axis were divided into 6 segments: anterior septum(AS),anterior wall(AW), laterior wall(LW), posterior wall(PW), inferior wall(IW) and mid-posterior septum(MP-Sept) automatically. Circumferential strain- time curve and radial strain- time curve of regional myocardium were obtained by STI. The peak value of the circumferential strain(Sc), peak value of the radial strain(Sr) and time to peak of strain were measured. The global parameters were obtained by averaging each strain of regional myocardium. All the data were analyzed by statistical software.Part 2: Quantitative evaluation of LV torsion in patients with ASD before and after the transcatheter closure by 2D-STIDynamic two-dimensional gray-scale images of LV short axis at two levels(basal level and apical level) were imported into Echo PAC workstation and analyzed. The basal rotation angle- time curve, apical rotation angle- time curve and torsion- time curve of LV were obtained in the similar manner, and the peak value of rotation angle, peak value of torsion angle, and time to peak were measured. Then those parameters were analyzed by statistic software.【Results】(1) Comparison of general parameters:Compared with NC,RVDd and RADd of ASD group increased(P<0.05)before transcatheter closure. At the same time, LVDd,LVEDV, LVESV, LVEF and LVSV of ASD group all decreased(P<0.05)compared with NC. RVDd and RADd of ASD group decreased(P<0.05)and LVDd increased(P<0.05)at 2 days after transcatheter closure when compared with the data before closure. Thoseparameters have showed no statistical difference between NC and ASD at 2-days after the transcatheter closure. LVEDV and LVSV of ASD increased( P<0.05) 2 days after transcatheter closure and increased to normal level further(P<0.05)6 months after the transcatheter closure. LVESV、LVEF increased(P<0.05)to normal level 2 days after the transcatheter closure.(2) Comparison of circumferential strain(Sc) of LV regional myocardiumCompared with NC,regional myocardial Sc of ASD group decreased(P<0.05). Sc of AS, AW, LW and PW increased significantly(P<0.05)2 days after the transcatheter closure and those parameters were higher than the NC. Six months after the transcatheter closure, those parameters reduced to the normal level(P<0.05). Sc of IW and MP-Sept increased(P<0.05)to the normal level 2 days after the closure surgery.(3) Comparison of radial strain(Sr) of LV regional myocardiumCompared with NC,regional myocardial Sr of ASD group decreased(P<0.05)except PW. Two days after the transcatheter closure these parameters increased(P<0.05)to the normal level. Sr of PW in ASD increased(P<0.05)compared with NC before the closure surgery. There have showed no statistical difference between NC and ASD at 2-days after the transcatheter closure. Sr of PW in ASD decreased(P<0.05)to normal level until6-months after the transcatheter closure.(4) Comparison of LV global strainGlobal circumferential strain(GCS) of LV in patients with ASD were lower than the NC( P<0.05). Two-days after undergoing transcatheter closure the GCS increased(P<0.05)and they were higher than the NC(P<0.05). Six-months after the transcatheter closure they reduced to the normal level(P<0.05).There were no statistical differences of LV global radial strain(GRS) between NC and ASD before closure. However, the GRS of ASD increased(P<0.05)and they were higher than the NC(P ﹤ 0.05) 2 days after the transcatheter closure. And it reduced to normal level(P<0.05)at six-months after the transcatheter closure.(5) Comparison of the peak value of rotation angle at LV basal level short axisCompared with NC,the peak value of rotation angle of LV at basal short axis levelin ASD decreased except PW(P<0.05)before closure. AW and LW of peak rotation angle increased to normal level after 2 days undergoing transcatheter closure(P<0.05). AS,IW and MP-Sept of peak rotation angle increased to normal level until 6-months after the undergoing transcatheter closure( P<0.05).The peak rotation angle of PW in ASD increased compared with NC and those parameters decreased to normal level 2 days after the transcatheter closure(P<0.05).(6) Comparison the peak value of rotation angle at LV apical level short axisThe peak rotation angle of LV at apical level short axis in ASD before closure were higher than NC(P<0.05). There was no obvious change 2 days after transcatheter closure.These parameters decreased to normal level until 6 months after the transcatheter closure(P<0.05).(7) Comparison of the peak value of torsion angle of the global LVThe peak value of torsion angle of the global LV in ASD were lower than the NC group(P<0.05). They increased to normal level 2 days after the transcatheter closure(P<0.05).(8) Comparison of the time to peakThe time to peak of strain, rotation angle and torsion angle of LV showed no statistical difference between ASD and NC, and these parameters above mentioned showed no statistical difference before and after the transcatheter closure.【Conclusion】(1) This study confirmed that the 2D-STI could evaluate the circumferential strain,radial strain, torsion and rotation of the LV before and after transcatheter closure.(2) LV systolic function reduced because of the increased volume load and pressure of RV.(3) Capacities of both RV and RA reduced after transcatheter closure. At the same time, the LV capacity increased and LV myocardium reconstructed. The geometric and reverse reconstruction of LV generated and LV systolic function was improved.(4) LV would reconstruct until six months after the transcatheter closure.