| BackgroundVelocity vector imaging (VVI) is a newly developed offline analysis software package that allows evaluation of myocardial tissue motion and velocity without the limitations of Doppler echocardiography. It utilizes a combination of speckle tracking with complex geometric analysis to follow the myocardium through the cardiac cycle. It offers an intuitive analysis of myocardial mechanics.During the past 25 years the rapid evolution of echocardiography has led to a greater understanding of fetal cardiac physiology. Traditionally fetal cardiac function has been measureed by subjective assessment of contractility and observation for hydrops fetalis. However, a precise understanding of fetal cardiac mechanics and function is lacking.Myocardial tissue motion and velocities have now been investigated in the fetal heart with the first published report indicating its feasibility appearing in 1999 by Harada et al. Since that time a number of preliminary studies have been performed validating the technique and reporting normal longitudinal velocities. In a recent report, Di Salvo et al demonstrated that evaluation of strain and strain rate can also be measured in the fetus with limited variability. These Doppler-based techniques are subject to some technical limitations and are dependent on obtaining an optimal angle of interrogation. It offers an intuitive analysis of myocardial mechanics. However, VVI has not been well studied in normal fetus and there is few reports of its use in the fetal congenital heart disease.Chapter 1 Evaluation of normal fetal cardiac function by velocity vector imaging[Objectives] To investigate the application and the influencing factors of velocity vector imaging for evaluation of myocardial mechanics in the normal fetal ventricles.[Methods] Selected were normal fetuses who underwent systemic ultrasonic examination in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009.Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing wall delay were performed on the left and right ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. Longitudinal strain, strain rate, and diastolic and systolic velocity were measured in the left ventricular free wall, ventricular septum, and right ventricular free wall. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.[Results]1. The measurements of global and segmental strain, strain rate, and opposing wall delay in left and right ventricles were obtained (n=147). There was no significant differences among groups (P>0.05). The strain of left ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-16.05±2.26%),(-16.87±4.01%),(-15.45±6.83%),(-15.71±5.68%),(-16.76±6.64%),(-15.96±6.63%),(-15.57±5.75%), respectively. The strain of right ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-16.13±1.78%),(-16.04±2.90%),(-16.06±6.79%),(-16.28±1.95%),(-16.51±2.28%),(-15.89±2.06%),(-15.71±3.36%), respectively. The strain rate of left ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-2.14±0.70/s),(-2.06±0.84/s),(-2.10±0.64/s),(-2.26±0.75/s),(-2.16±0.55/s),(-2.21±0.79/s),(-2.08±0.65/s), respectively. The strain rate of right ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (-2.06±0.98/s),(-2.24±1.13/s),(-2.08±0.76/s),(-2.10±1.42/s),(-2.03±0.75/s),(-1.96±1.17/s),(-1.93±0.79/s).The time of opposing wall delay of left ventricular strain, strain rate and velocity were (94.30±3.93ms),(93.68±3.17ms),(92.22±4.31 ms).The time of opposing wall delay of right ventricular strain, strain rate and velocity were (93.23±51.81ms),(96.92±47.60ms),(91.19±52.93ms). There was no significant differences among groups (P>0.05).2. The measurements of global and segmental velocity in left and right ventricles were obtained (n=147). The velocity of left ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (1.41±0.29cm/s),(2.35±0.99cm/s),(1.73±0.92cm/s),(0.81±0.37cm/s),(0.58±0.30cm/s),(1.19±0.60cm/s),(1.80±0.87cm/s),respectively. The velocity of right ventricular global, base septal, mid septal, apical septal, apical free wall, mid free wall, base free wall were (1.53±0.33cm/s),(2.40±1.18cm/s),(1.81±0.89cm/s),(1.06±0.60cm/s),(0.78±0.41cm/s),(1.27±0.51cm/s),(1.84±0.79cm/s). There was significant differences among global and six segmental group in left ventricle (F=133.463, P=0.000) and in right ventricle (F=78.198, P=0.000). The comparison between left and right ventricular velocity (global, apical septal, apical free wall) showed significant differences (1.41cm/s VS 1.53cm/s, t=3.033, P=0.003; 0.81cm/s VS 1.06cm/s, t=4.458, P=0.000; 0.58cm/s VS 0.78cm/s, t=4.721, P=0.000). The comparison between left and right ventricular velocity (base septal, mid septal, mid free wall, base free wall) showed no significant differences (P>0.05).The velocity decreased from the base to apical ventricles.3. The measurements of strain, strain rate, diastolic and systolic velocity, and opposing wall delay in the left ventricular free wall, ventricular septum, and right ventricular free wall were obtained (n=145). The systolic and diastolic velocity in the left ventricular free wall, ventricular septum, and right ventricular free wall were (1.11±0.72cm/s), (1.24±0.50cm/s), (1.23±0.59cm/s), (1.16±0.67cm/s), (1.22±0.64cm/s), (1.16±0.64cm/s), and the strain were (-15.93±6.66%), (-15.56±6.79%), (-15.89±2.06%), and strain rate were (-2.17±0.55/s), (-2.10±0.64/s), (-2.08±0.76/s). The paired comparison between groups showed no significant differences (P<0.01).4. The gestational age had significant positive correlation with the velocity in normal fetus (n=145, P<0.01).The fetal heart rate had significant positive correlation with the strain in normal fetus (P<0.01).5. Velocity vector images and learning curves of longitudinal velocity, strain, and strain rate were obtained. The learning curve showed that the velocity decreased from the base to the apex and that the strain and strain rate remained stable.[Conclusions] Measurement of cardiac strain and strain rate using VVI can be applied to evaluate global and segmental ventricular motion and function.Chapter 2 Evaluation of hypoplastic left heart syndrome in fetus by velocity vector imaging[Objectives] To investigate the application of velocity vector imaging for evaluation of myocardial mechanics in hypoplastic left heart syndrome.[Methods] Selected were fifty-six fetus who underwent systemic ultrasonic examination and had been diagnosed as hypoplastic left heart syndrome in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009. The control was healthy pregnant women without contributable history. The case and control group were 1:1 paired. Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing opposing wall delay were performed on the right and left ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.[Results]1. The comparison of global strain, strain rate, velocity, and opposing opposing wall delay between HLHS and control group showed significant differences (P<0.01). The mean differences of left ventricular strain, strain rate, and velocity between normal and HLHS fetus were (4.08±6.71%), (0.53±0.86/s), (-0.27±0.63cm/s). The mean differences of left ventricular opposing wall delay in strain, strain rate, and velocity between normal and HLHS fetus were (801.75±335.26ms,923.08±477.22ms, 850.80±391.45ms). The mean differences of right ventricular strain, strain rate, and velocity between normal and HLHS fetus were (3.99±9.15%), (0.32±0.97/s), (-0.76±0.70cm/s). The mean differences of right ventricular opposing wall delay in strain, strain rate, and velocity between normal and HLHS fetus were (95.07±74.98ms,75.40±77.41ms,89.27±82.00 ms).2. The gestational age had no significant correlation with the velocity in HLHS fetuses (P>0.05).The fetal heart rate had no significant correlation with the strain rate in normal fetus (P>0.05).[Conclusions] Measurement of VVI indices can be applied to evaluate global and segmental ventricular motion and function in the HLHS fetus.Chapter 3 Evaluation of hypoplastic right heart syndrome in fetus by velocity vector imaging[Objectives] To investigate the application of velocity vector imaging for evaluation of myocardial mechanics in hypoplastic right heart syndrome.[Methods] Selected were twelve fetus who underwent systemic ultrasonic examination and had been diagnosed as hypoplastic right heart syndrome in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009. The control was healthy pregnant women without contributable history. The case and control group were 1:3 paired. Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing opposing wall delay were performed on the right and left ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.[Results] 1. The comparison of global strain, strain rate, velocity, and opposing wall delay between HRH and control group in right ventricle showed significant differences (P <0.01). The mean differences of right ventricular strain, strain rate, and velocity between normal and HRH fetus were (4.02±1.63%), (0.70±0.15/s), (-0.54±0.10cm/s). The mean differences of right ventricular opposing wall delay in strain, strain rate, and velocity between normal and HRH fetus were (652.60±312.17ms,949.06±430.19ms,876.86±543.97 ms). The comparison of global strain, strain rate, velocity, and opposing wall delay between HRH and control group in left ventricle showed no significant differences (P>0.05).The mean differences of left ventricular strain, strain rate, and velocity between normal and HRH fetus were(1.28±1.18%),(0.24±0.16/s),(-0.28±0.08/s). The mean differences of left ventricular opposing wall delay in strain, strain rate, and velocity between normal and HRH fetus were (78.58±13.62ms,89.12±18.45ms,128.57±14.06ms).2. The gestational age had no significant correlation with the velocity in HLHS fetuses (P>0.05).The fetal heart rate had no significant correlation with the strain rate in normal fetus (P>0.05).[Conclusions] Measurement of VVI indices can be applied to evaluate global and segmental ventricular motion and function in the HRH fetus.Chapter 4 Evaluation of noncompaction of the ventricular myocardium in fetus by velocity vector imaging[Objectives]To investigate the application of velocity vector imaging for evaluation of myocardial mechanics in noncompaction of the ventricular myocardium.[Methods] Selected were nine fetus who underwent systemic ultrasonic examination and had been diagnosed as noncompaction of the ventricular myocardium in Shenzhen maternity and child healthcare hospital from December 2007 to December 2009. The control was healthy pregnant women without contributable history. The case and control group were 1:3 paired. Two-dimensional 4-chamber images of the heart were interrogated offline using Syngo US Workplace VVI software. Measurements of global and segmental longitudinal velocity, strain, strain rate and opposing wall delay were performed on the right and left ventricle. Comparison was made between each segmental and global, and left and right ventricular measurement respectively. Learning curves of velocity, strain, and strain rate and velocity vector images were performed. The correlation of above measurements with gestational weeks and fetal heart rate was analyzed.[Results]1. The comparison of global and segmental strain, strain rate, velocity, and opposing wall delay between NVM and control group showed significant differences (P< 0.01).2. The gestational age had no significant correlation with the velocity in HLHS fetuses (P>0.05).The fetal heart rate had no significant correlation with the strain rate in normal fetus (P>0.05).[Conclusions] Measurement of VVI indices can be applied to evaluate global and segmental ventricular motion and function in the noncompaction of the ventricular myocardium fetus...
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