Speckle Tracking Echocardiographic Analysis Of Left Ventricular Geometry And Systolic Function During Perioperation Of Ventricular Septal Defect Surgery

Since open-heart surgery with cardiopulmonary bypass (CPB) began with closure of an atrial septal defect by John Gibbon in 1953[1], the CPB have been applied widely in the field of cardiac surgery. Cardiac surgery with CPB has been used to correct many cardiac abnormalities for congenital or acquired heart diseases, and provide opportunity for survival, but it is also associated with a defined degree of preoperative and postoperative morbidity and mortality related severe complication, such as low cardiac output syndrome, arrhythmias, heart failure. Potential mechanisms have included the significant change of hemodynamics immediate after operation and the procedures themselves, such as CPB related systemic inflammatory response syndrome, direct surgical aggression on the heart tissue, injury effect of hypothermia and/or ischemia and reperfusion . Identification of patients who are at higher risk may allow better targeting of investigation, monitoring, and treatment, ultimately leading to an improvement in patient outcome.The important determinants of left ventricular (LV) systolic function are ventricular geometry, preload, afterload, contractility, synchrony of contraction and heart rate . Echocardiography is considered to be an ideal tool for LV function assessment. Among the several LV function echocardiographic indexes, the most commonly used in the clinical setting are LV ejection fraction (EF) and shortening fraction (FS). However, EF and FS are load-dependent parameters and may not reflect the regional myocardium contractile function.A novel approach to quantify regional LV function from routine gray-scale 2D echocardiographic images, known as speckle tracking (STE), calculates myocardial strain independent of angle of incidence. The software uses conventional gray-scale B-mode recordings and tracks myocardial speckles, which serve as natural acoustic markers. Myocardium multi-dimensional, i.e. longitudinal, radial and circumferential deformation can be measured from echocardiographic views. Experimental and clinical studies have demonstrated that the SET method can assess the LV regional and global contractile alterations accurately in healthy subjects, in the settings of acute and chronic ischemia, dyssynchrony, and cardiomyopathy .Ventricular septal defects (VSD) are a common congenital heart disease, and their repair is one of the most representative cardiac operations. In this study, we used the STE technique to evaluate the effect of cardiac surgery with CPB on the LV geometry, LV regional and global contractile synchrony and function associate with VSD surgery. The study was divided into three parts as follows:Part 1. Assessment of left ventricular geometry during perioperation of VSD surgery using 2D echocardiographyThe aim of this part was to assess the effect of cardiac surgery with CPB on the LV geometry associate with the repair of VSD using 2D echocardiography. The VSD surgical patients were involved in this study. The patients were divided into three groups according the size of the VSD: small (S), moderate (M) and large (L) group.Results:â‘ pre-operation: compared with the values in the control group, the LV end-systolic and end-diastolic longest diameter (Ls, Ld) in longitudinal section, radial anterior to posterior diameter (APs, APd), and lateral to septal diameter (LSs, LSd) in cross section, sphericity index (SIs, SId), [(D₁+D₂+D₃)/3L]d,[(D₁+D₂+D₃)/3L]s,[2D₁/L]d,[2D₁/L]s, LSd/APd, LSs/APs, and fractional shortening of L, D₂, LS, AP (FSL, FSD₂, FSLS, FSAP) showed no significant difference in the S VSD group. Ld, Ls, LSd, LSs, APd, APs, SIs, [(D₁+D₂+D₃)/3L]d, [2D₁/L]d, FSD₂, FS_LS increased significantly (P<0.05 or 0.01), SId, [(D₁+D₂+D₃)/3L]s, [2D₁/L]s, LSs/APs decreased significantly and FS_AP, LSd/APd showed no significant difference in the M VSD and L VSD groups. FSL showed no significant difference in the M VSD group, and FSL decreased significantly in the L VSD group (P<0.05).â‘¡within 6 hours after the operation, the Ld, Ls, LSd, APd, [2 D1/L]d, FSLS significantly lower than that before operation in the S VSD group (P<0.05), the others parameters showed no significant difference when compared with the preoperation. Ld, Ls, LSd, APd, APs, LSd/APd, SIs, [(D₁+D₂+D₃)/3L]d, [2 D₁/L]d, FSD₂, FSLS were significantly lower (P<0.05) and SId, [(D₁+D₂+D₃)/3L]s, [2 D₁/L]s, LSs/APs were significantly higher (P<0.05) than those before operation in the M and L VSD groups, the others parameters showed no significant difference between the preoperation and postoperation.â‘¢postoperation: Compared with the values in the control group, all the parameters showed no significant differences in the S VSD group. The FSLS, FSAP decreased significantly (P<0.05), LSs, APs increased significantly (P<0.05), and the other parameters showed no significant differences in the M VSD group. The Ld, SIs, LSd, APd, LSs, APs, [(D₁+D₂+D₃)/3L]d, [2 D₁/L]d values increased significantly (P<0.05), [(D₁+D₂+D₃)/3L]s, [2 D₁/L]s, LSd/APd, LSs/APs, FSLS, FSAP values decreased significantly (P<0.05), and the other parameters showed no significant differences in the L VSD group.Part 2. Assessment of LV regional and global contractile synchrony during perioperation of VSD surgery using speckle tracking echocardiographyThe aims of this part were to assess the effect of cardiac surgery with CPB on the LV regional and global contractile synchrony associate with the repair of VSD using speckle tracking echocardiography combined with strain parameter, and to assess the value of speckle tracking echocardiography in the evaluation of LV contractile synchrony during perioperation. The VSD surgical patients were involved in this study; the patients were divided into three groups according the size of the VSD: small (S), moderate (M) and large (L) group.Results:â‘ preoperation: Compared with the values in the control group, the standard deviation of the time to peak systolic longitudinal strain (Tsl), peak systolic radial strain (Tsr) and peak systolic circumferential strain (Tsc) in all segments (Tsl-SD, Tsr-SD, Tsc-SD) and the maximal temporal difference of Tsl, Tsr, Tsc (Tsl-diff, Tsr-diff, Tsc-diff) in all segments showed no significant differences in the S group. The Tsl-SD, Tsl-diff increased significantly (P<0.05), and the other parameters showed no significant differences in the M VSD group. The Tsl-SD, Tsl-diff, Tsc-SD, Tsc-diff increased significantly (P<0.05), and the other parameters showed no significant difference in the L group. The longest Tvl, Tvr and Tsc occurred in the antero-septal or septal segments in all three groups.â‘¡within 6 hours after the operation, the all parameters showed no significant difference as compared with the preoperation in the S VSD group. All the parameters were higher significantly in the M and L groups than those before operation (P<0.05).â‘¢postoperation: Compared with the values in the control group, the all parameters showed no significant difference in the S VSD group. All the parameters increased significantly in the M and L VSD groups (P<0.05). The longest Tvl, Tvr and Tsc occurred in the antero-septal or septal segments in all three groups.Part 3. Assessment of LV regional and global contractile function during perioperation of VSD surgery using speckle tracking echocardiographyThe aims of this part were to assess the effect of cardiac surgery with CPB on the LV regional and global contractile function associated with the repair of VSD using speckle tracking echocardiography combined with strain and strain rate parameters, and to assess the value of speckle tracking echocardiography in the evaluation of LV contractile function during perioperation. The VSD surgical patients were involved in this study; the patients were divided into three groups according the size of the VSD: small (S), moderate (M) and large (L) group.Results:â‘ preoperation: Compared with the values in the control group, the LV end-distolic volume (LVEDV), end-systolic volume (LVESV), and LV ejection fraction (LVEF) showed no signigicant difference in the S VSD group; the LVEDV increased significantly (P<0.05) and LVESV, LVEF showed no significant difference in the M group; the LVEDV, LVESV increased significantly (P<0.05) and LVEF showed no significant difference in the L group. The longitudinal strain (SL), radial strain (SR), circumferential strain (SC), and longitudinal strain rate (SrL), radial strain rate (SrR), and circumferential strain rate (SrC) in all segments showed no significant difference in the S VSD group; the SL, SR, SC, SrL, SrR, SrC values in all segments increased significantly(P<0.05) in the M VSD group; the SL, SrL values decreased significantly(P<0.05) in all segments and the SR, SC, SrR, SrC decreased significantly in anterior, posterior, and inferior walls (P<0.05) and showed no significant difference in anter-septal, septal, lateral walls in the L VSD group.â‘¡within 6 hours after the operation, compared with the values before operation, the LVEDV, LVESV, LVEF showed no significant difference in the S VSD group; The LVEDV, LVESV and LVEF decreased significantly in the M and L VSD groups (P<0.01). The SL, SR, SC, SrL, SrR, SrC in all segments decreased significantly in the three groups (P<0.05 or <0.01).â‘¢postoperation: Compared with the values in the control group, the LVESV, LVEDV, and LVEF showed no significant difference in the S and M VSD groups, the LVEDV, LVESV increased significantly and LVEF decreased significantly in the L VSD group (P<0.05). The SL, SR, SC, SrL, SrR, SrC decreased significantly in all segments in the three groups (P<0.01).Conclusions:Based on the present study, our conclusions are as follows:â‘ The LV dynamic geometry changed and trended to normalize in the early postoperative period. In longitudinal section, the LV is more elliptical in the end-diastole and more spherical in the end-systole as compared with preoperation. In cross section, the LV geometry did not changed in the end-diastole, was still circular, similar to the preoperation, but it changed from elliptical model of preoperation to spherical model after operation in the end-systole. The LV geometry was normalizing immediately after operation in the S VSD group, and was gradual normalizing over time after operation in the M and L groups.â‘¡VSD repair had no significant effect on the LV regional and global contractile synchrony in the S VSD group, but it impaired the LV contractile synchrony in the M and L VSD groups.â‘¢Speckle tracking echocardiography combined with strain parameter can assess accurately the change of LV regional and global contractile synchrony during perioperation of cardiac surgery.â‘£The VSD repair impaired the LV regional and global contractile function immediately after operation in the three groups. We presumed that reduction in LV preload and myocardium injury related the procedures themselves were the primary causes.⑤Speckle tracking echocardiography combined with strain and strain rate parameters can assess accurately the change of LV regional and global contractile function during perioperation of cardiac surgery. Strain and strain rate are also load-dependent parameters and may not reflect the true myocardial contractile status, but it can demonstrate the presence of early abnormalities of myocardial contractile function despite a normal LV EF.