| Cardiac mechanical dyssynchrony usually exist in chronic heart failure(CHF) patients, which present as atrio-ventricular dyssynchrony, interventricular dyssynchrony and intraventricular dyssynchrony. Dyssynchrony motion could decrease the efficience of ventricular systole and cause disadvantages of cardiac hemodynamics. Cardiac resynchronization therapy(CRT) is a kind of new treatment for chronic heart failure. Based on optimizing atrio-ventricular interval, right-left ventricular interval and intraventricular interval, CRT shows positive effect on mechanical dyssynchrony motion and hemodynamics. It was reported that the evidence of cardiac mechanical dyssynchrony pre-operation was an important predictor for the benefit of CRT. Compared with atrio-ventricular dyssynchrony and interventricular dyssynchrony, intraventricular dyssynchrony was more useful in the prediction of CRT response.Using real-time three-dimensional echocardiography and two-dimensional speckle tracking imaging, the present study made comparisons of mechanical dyssynchrony between normal people and CHF patients. The relationship of systolic dyssynchrony and left ventricular systolic dysfunction was also evaluated. Referring to classical tissue Doppler imaging, we explored the most valuable parameter for the prediction of short-term CRT response. Finally, correlations among three techniques were analysed respectively.Part1Evaluation of left ventricular dyssynchrony and its correlation with systolic function by real-time three-dimensional echocardiographyObjective The purpose of this study was to explore the clinical value of real-time three-dimensional echocardiography (RT-3DE) in identifying left ventricular systolic dyssynchrony in heart failure patients with severe damage of cardiac function, and to analyse the relationship between mechanical dyssynchrony and left ventricular systolic function.Methods Twenty-two healthy volunteers (control group) and twenty heart failure patients (case group) were enrolled in this study. Clear Full volume images of the while heart were aquired using RT-3DE. The time to minimal systolic volume (Tmsv) of each segment were measured in time-volume curve derived by Qlab software, and a mean value of Tmsv for the same segment in each group was calculated (Tmsv’). The standard deviation (Tmsv-SD) and the maximal difference (Tmsv-Dif) of time to minimal systolic volume were calculated for basal level、mid level、apical level、12segments and16segments. Dyssynchrony parameters of 12segments and16segments standardized by heart rate (Tmsv-SD%、Tmsv-Dif%) were computered automatically by Qlab. All the parameters were compared between the two groups. The correlation between left ventricular ejection fraction (LVEF) derived from RT-3DE and dyssynchrony parameters were analyzed in case group.Results There were no significant differences among1-17Tmsv’within each group (P>0.05). No significant differences were found between two groups for Tmsv’derived from the same segment (P>0.05). Dyssynchrony parameters of three levels、12segments and16segments in case group were remarkably higher than those in control group (P<0.01). LVEF correlated closely with all of the dyssynchrony parameters in case group (r=-0.511-0.839, P<0.01), and16segments parameters showed the strongest correlation. Parameters standardized by heart rate were more strongly correlated with LVEF than non-standardized ones (r=-0.730～-0.839VS r=-0.626～-0.683)Conculution RT-3DE is a feasible tool for quantifying left ventricular mechanical dyssnchrony. Intraventricular mechanical dyssynchrony exist in CHF patients whose cardiac function have been impaired severely, and it will further impair left ventricular systoic function. Parameters standardized by heart rate may be the more acurate ones to identify left ventricular mechanical dyssnchrony. Part2Evaluation of left ventricular systolic dyssynchrony in chronic heart failure patients by two-dimensional speckle tracking imagingObjective The purpose of this study was to evaluate left ventricular mechanical dyssynchrony in chronic heart failure (CHF) patients using two dimensional speckle tracking imaging (2D-STI), and to compare the usefulness of three patterns of myocardial deformation in mechanical dyssynchrony assessment.Methods37CHF patients were enrolled in this study. According to left ventricular ejection fraction(LVEF), the patienst were classified into two subgroups:LVEF≤35%(group A),35%<LVEF<50%(group B).35healthy volunteers comprised the control group (group C). Standard2D images were acquired in the2-,3-and4-apical views as well as the parasternal short-axis views at the level of mitral valve and papillary muscles. The time to peak-systolic strain and strain rate were measured for each segment in the level of the mitral valve and papillary muscles in Qlab software. Dyssychrony parameters were defined as the standard deviation and the maximal time delay of time to peak-systolic strain and strain rate for 12segments. Parameters were compared among three groups respectively. The cut-off value of each parameter were derived from group C based on statistical principles. Dyssychrony rate of each parameter were calculated in group A and B, and compared within each group respectively. The relationships between dyssynchrony patameters, LVEF, and QRS duration were explored in CHF patients.Results Compared with group C, all the dyssychrony parameters in group A were significant higher (P<0.05), while some of the parameters (Tsl-12SD, Tsl-12Dif, Tslr-12SD, Tslr-12Dif and Tsr-12SD) in group B were remarkable higher (P<0.05). A significant difference among dyssychrony rates was noted within both group A and B (P<0.05), and longitudinal strain parameters were the highest value in both subgroups. LVEF was related to all three forms of strain/strain rate (P<0.05), whereas no relationship existed between QRS duration and dyssychrony parameters (P>0.05).Conclusions2D-STI is useful in quantifying left ventricular systolic dyssychrony in CHF patients. CHF patients have different extents of left ventricular mechanical dyssychrony. Left ventricular systolic function was closely related to mechanical dyssychrony, whereas QRS duration showed no significant correlation. Longitudinal strain parameter shows the best detectability of dyssynchrony motion. Part3Evaluation of CRT short-term response in chronic heart failure patients by real-time three-dimensional echocardiography and two-dimensional speckle tracking imagingObjective The purpose of this study was to evaluate short-term response to cardiac resynchronization therapy (CRT) in chronic heart failure patients by real-time three-dimensional echocardiography (RT-3DE) and two-dimensional speckle tracking imaging(2D-STI). Combined with classical tissue Doppler imaging(TDI), we explored the most valuable parameter for the prediction of left ventricular reverse remodelling post CRT. Finally, correlations among the three techniques were analysed respectively.Methods22chronic heart failure patients received CRT were enrolled in this study. Standard2D images were acquired in the2-,3-and4-apical views as well as the parasternal short-axis views at the level of mitral valve and papillary muscles. Dyssynchrony patameters derived from three techniques were calculated respectively. RT-3DE parameters were defined as the standard deviation and the maximal difference of time to minimal systolic volume for16segments.2D-STI parameters were defined as the standard deviation and the maximal time delay of time to peak-systolic strain for12segments. TDI parameters were defined as the standard deviation of time to peak-systolic velocity for12segments. All the parameters were standardized by heart rate. Response to CRT were defined as a relative decrease in left ventricular end-systolic volume≥15%.Results Compared with pre-operation, response group showed a significant decrease in left ventricular end-systolic volume (P<0.05) and a significant increase in left ventricular ejection fraction (P<0.05). There were remarkable decreases in longitudinal parameters derived from2D-STI and TDI parameters in response group (P<0.05). None of the three technique parameters had significant differences in non-response group (P>0.05). Compared with non-response group, longitudinal parameters pre-operation were remarkable higher in response group (P<0.05). A cut-off value of Tsl-12SD (%R-R)≥7.61%was able to predictc response to CRT with a sensibility of82.10%and a specificity of79.00%. Both Tsl-12SD (%R-R) and Tsl-12Dif (%R-R) had positive correlation with TDI parameters (r=0.557, P<0.05VS r=0.586, P<0.05), while RT-3DE parameters show no relationship with2D-STI and TDI ones (P>0.05)Conclusions It is feasible to identify short-term improvement of intraventricular mechanical dyssynchrony after CRT by2D-STI longitudinal strain and TDI. Longitudinal strain is more usefull in predicting left ventricular reverse remodelling post-operation. TDI showed a good linear relation with2D-STI longitudinal strain, while RT-3DE parameters show no relationship with2D-STI and TDI ones. |
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