Study Of Left Ventricular Asynchrony In Children With Congestive Heart Failure By Quantitative Tissue Velocity Imaging

Part I : Evaluation of Inter- and Intraventricular Synchrony in Normal Children by Quantitative Tissue Velocity ImagingBackground and objective In order to remain normal function, the heart itself must keep synchrony in antrum and ventricle. Many studies were reported that various degrees of asynchronous phenomenon can be found in patients with coronary heart disease, hypertrophic and dilated cardiomyopathy, bundle branch block, and so on. Congestive heart failure (CHF), in which asynchronous phenomenon is more severe, is caused by the end-stage of various heart diseases. When asynchrony remains in ventricle, there will be disharmonic ventricular systole, even contradictory movements in ventricular wall which can cause descend of systolic function. Furthermore, there will also arise asynchrony of ventricular diastole which can cause shortening of filling time in left ventricle, valid myocardial movement, mitral regurgitation, and aggravate the heart function. To assess myocardial asynchrony, the traditional methods, including radioisotope, magnetic resonance imaging (MRI), electrocardiograph (ECG), echocardiography of M-mode and two dimensional imaging, are limited because of respective shortage. The quantitative tissue velocity imaging (QTVI) can analyze multiple segments of myocardium simultaneously along long-axis of heart, having significant advantages in assessing myocardial asynchrony. The purposes of this study was to evaluate the inter- and intraventricular synchrony in normal children. Materials and methods Quantitative Tissue velocity imaging (QTVI) was performed in 100 normal children (50 boys, 50 girls; age from 1 month to 14 years; average age is 7.5±2.9) using apical four-chamber view and two- chamber view. The flowing segments were investigated: posteroseptal, lateral wall, anterior wall and posterior wall of left ventricle. Every left ventricular wall was divided into three segments including basal segment (Bas), middle segment (Mid) and apex segment (Apex) on average. Sampling points were set at myocardial layer of interface between valve and Bas, Bas and Mid, Mid and Apex. Twelve QTVI curves of four walls and myocardial movement curve of interface between valve of right ventricular lateral wall and basal segment in apical four-chamber view were obtained. The time from onset of QRS complexes to peak velocity during systole and diastole (Ts and Te ) were measured in myocardial movement curves of every segments. Ts and Te represent the time of electromechanical systole and diastole of myocardium respectively.Results1. Myocardial synchrony of LV in normal children:①The Ts was no difference in different segments of the same wall in LV (P>0.05); There was remarkable difference of Ts in the septum, anterior wall, lateral wall and inferior wall (P<0.05); the difference of Te in LV different segments had no statistical significance (P>0.05).②Change regulation of Vs and Ve in every segments of LV: Vs and Ve of three segments (Bas, Mid and Apex) in same wall decreased in gradually: Bas>Mid>Apex.2. Ts and Te of basal segment in right ventricular lateral wall:①Ts of basal segment in right ventricular lateral wall was delayed 41.0±15.7ms compare to mean Ts of four walls in LV (P<0.01).②There was no difference between Te of basal segment in right ventricular lateral wall and that of four walls in LV (P>0.05).3. Influenced factors of Ts, Te, Vs and Ve:①The mean Ts had negative correlation with heart rate.②The mean Te had negative correlation with heart rate and diastolic pressure. Conclusions1. The systolic and diastolic movement in different segments of the same wall was highly synchronized and there was slightly difference of systolic synchrony in some LV walls. These may be the characteristics of normal children.2. The study found it was different from adult that Ts of septum and anterior wall in LV was slight longer than that of lateral and inferior wall and systolic wave was dull in QTVI in child. It need further study to confirm the concrete mechanism.3. The myocardial movement was basically synchrony but Ts had slight difference between LV and RV in child.Part II: Study of left Ventricular Asynchrony in Children Patients with Congestive Heart Failure by Quantitative Tissue Velocity ImagingBackground and objective Congestive Heart failure (CHF) is the end-stage of various heart diseases. Because of the high morbidity and mortality, treatment of CHF to increase the survival rate remains one of the the major challenges in health care practice. Cardiac resynchronization therapy (CRT) is an original, effective and no medicamental method in treating CHF. Recently, how to evaluate the electromechanical systole in ventricle, choose the appropriate patients before CRT and observe curative effect after therapy becomes a hot topic in researchful field. Based on ultrasonic technique, evaluation of systolic asynchrony becomes a valuable technique increasingly used in choosing the appropriate patients before CRT and observing curative effect after therapy. The quantitative tissue velocity imaging (QTVI), developed on the basis of Doppler tissue imaging (DTI), can obtain the movement messages in every segments of myocardium simultaneously. On the contrary, traditional DTI technique, using the method of pulse Doppler, can only observe one point of myocardial movement each time. Furthermore, it is more sensitive, convenient and rapid than traditional method for assessing the myocardial asynchrony because of its facility, accuracy and reduplication. The purposes of this study were:①To observe the asynchronous movement of LV in children with CHF.②To evaluate the relationship between LV asynchrony in children with CHF and function of LV, QRS duration, remodeling and mitral regurgitation.Materials and methods Forty Normal children and thirty children with CHF were studied by QTVI using apical four-chamber view and two- chamber view. In CHF group, the study population consisted of 3 patients with endocardial fibroelastosis, 16 patients with dilated cardiomyopathy, 8 patients vital myocarditis and 3 patient with noncompaction of ventricular myocardium(the function of the heart: II-IV grades). Apparatus used GE Vivid 7 color Doppler with 3.0MHz frequency probe. The flowing segments were investigated: posteroseptal, lateral wall, anterior wall and posterior wall of left ventricle. Every left ventricular wall was divided into three segments including basal segment (Bas), middle segment (Mid) and apex segment (Apex) on average. Sampling points were set at myocardial layer of interface between valve and Bas, Bas and Mid, Mid and Apex. Twelve QTVI curves of four walls and myocardial movement curve of interface between valve of right ventricular lateral wall and basal segment in apical four-chamber view were obtained. The time from onset of QRS complexes to peak velocity during systole and diastole (Ts and Te) were measured in myocardial movement curves of every segments. Ts and Te represent the time of electromechanical systole and diastole of myocardium respectively. The maximal difference in Ts and Te within the same wall (Intra-△Ts and Intra-△Te) and all 12 segments (Max-△Ts and Max-△Te) of LV were calculated. Intra-△Ts and Intra-△Te represent the asynchronous systolic and diastolic index of the different segments in same myocardial wall respectively. Max-△Ts and Max-△Te represent the asynchronous systolic and diastolic index of the whole left ventricle respectively. Parameters of LV function and the other measures indexes included:①Ejective fraction of LV (LVEF);②Tei index;③The preejection period (PEP) of aorta (Q-A) and pulmonary artery (Q-P) and their difference (Q-AP).④The mean of systolic peak velocities and early diastolic peak velocities of mural annulus of six walls (Mean Vs and Mean Ve,);⑤End diastolic diameter of LV (LVEDd);⑥Spherical index of LV (LVSI);⑦The ratio of area of mitral regurgitation is area of left atrium (MRA/LAA);⑧QRS duration. Results1. There was no remarkable difference in age between the control group and the CHF group (P>0.05). But in those two groups, there were statistically significant in heart rate, QRS duration, Tei index and LVEF (P <0.01).2. Intra-△Ts, Intra-△Te, Max-ATs, Max-△Te, mean Vs and Ve in CHF group were significantly prolonged compared with those parameters of control group (P3. In CHF group, Max-ATs was negatively correlated with LVEF (r=-0.54, P<0.05) and positively correlated with Tei index (r=0.58, P<0.01) ,but it was not correlated with QRS duration. Max-△Te was positively correlated with QRS duration (r=0.57, P<0.01) and not correlated with LVEF and Tei index.4. Q-A,Q-P and Q-AP in CHF group were significantly prolonged compared with control group(P <0.01).Conclusions1. It is similar to adult that asynchrony in LV exists within not only the different walls of same segment but also the different segments of same wall in children with CHF.2. The LV systolic asynchrony in children with CHF have close relations with LVEF, mean Vs and LVEDd and diasolic asynchrony have close relations with mean Ve and MRA, which indicates asynchrony in LV can influence the LV function, remodeling and mitral regurgitation.3. Existing in children with CHF, the obvious synchrony in LV and RV can cause further injury of the heart function.4. QRS duration has a certain relation with the diasolic index of myocardial asynchrony.