Assessment Of Tricuspid Annular Motion And Right Ventricular Tei Index In Normal Children By Quantitative Tissue Velocity Imaging

Background and Objective:It's important to assess right ventricular (RV) function in congenital and acquired cardiac abnormalities in children. Tissue Doppler imaging (TDI) and Tei index have been recognized as sensitive and reliable methods in quantitative assessment of global RV function. In this study, we used quantitative tissue velocity imaging (QTVI) which derived from TDI to measure velocity and time intervals in tricuspid annulus in 216 normal children. We aimed to evaluate the effects of age, heart rate (HR), body surface area (BSA) and tricuspid valve annulus diameters (TAD) on the QTVI velocity parameters and QTVI-Tei index, and to compare the Tei index by the two methods of QTVI and pulsed wave Doppler (PWD).Methods:A total of 216 normal children were enrolled in this study, who took the regular health care visits in our hospital from November 2009 to March 2010. We divided them into 7 groups:under 1 month of age group,1 month-of age group,6 months-of age group,1 year-of age group,3 years-of age group,6 years-of age group and 9-12 years of age group. GE Vivid 7 and Vivid 7 dimension color Doppler scanners with 1.5-8.0 MHz transducers were used to detect the above children, which could analyze and post-process QTVI images with Echopac workstation.Transtricuspid flow velocity during early diastole (E) and late diastole (A) were measured by PWD in standard apical four-chamber view. RV outflow tract wave by PWD was recorded in parasternal long axis view of outflow tract. The images from standard apical four-chamber view and apical two-chamber view of right heart were recorded for three cardiac cycles.The QTVI sample volume was set at tricuspid annulus of anterior (AAP), septal (SAP) and posterior (PAP) attachment points to acquire speed-time curve. Peak systolic velocity (Sa), peak early (Ea) and late (Aa) diastolic velocity of tricuspid annulus were measured, and Ea/Aa and E/Ea ratio was calculated as well. PWD a component was measured from the trailing edge of the PWD tricuspid flow late diastolic A wave to the leading edge of the subsequent PWD tricuspid flow early diastolic E wave. The b component for the PWD was measured from the leading edge to the trailing edge of the PWD RV outflow tract tracing. The Tei index determined by PWD method was calculated as (a-b/b). QTVI a component was measured from the starting point of QRS wave in ECG to the leading edge of the subsequent early diastolic tricuspid annular QTVI Ea wave. The b component was measured from the leading edge of the systolic tricuspid annular QTVI Sa wave to the trailing edge of the Sa wave. The Tei index determined by QTVI method was calculated as (a-b/b).Results:(1) Sa and Ea were the lowest in children under 1 month of age group [the mean value of AAP, PAP and SAP:Sa (5.61±1.12)cm/s, Ea (7.33±2.12)cm/s]; The above two values increased with age and more rapidly at less than 1 year-of age group. The ratio of Ea/Aa from AAP and PAP were both less than 1 at the age of under 1 month (AAP:0.97±0.29, PAP:0.91±0.26), while more than 1 at other ages. It increased with age before 3 years-of age. E/Ea from all positions decreased with age before 1 year-of age.(2) Sa, Ea and Aa were the lowest from the location of SAP, and followed by those from PAP and AAP (P＜0.05).(3) Sa, Ea, Aa, Ea/Aa and E/Ea correlated significantly with age, HR, BSA and TAD. Multivariate regression analysis showed that TAD was the main factor that influenced Sa, Ea/Aa and E/Ea, and it was the independent factor that influenced Ea at tricuspid annulus. HR influenced Aa independently.(4) QTVI-Tei index and PWD-Tei index were both higher in age group of under 1 month(QTVI-Tei=0.39±0.03, PWD-Tei=0.38±0.05)than those in the group of 1 month-of age (P＜0.05).(5) Overall average Tei index values in RV by the two methods were:QTVI-Tei= 0.37±0.05 and PWD-Tei= 0.35±0.05. There was statistically significant difference between them (P<0.05), the correlation coefficient between them was 0.594.(6) Correlation analysis showed age, BSA and TAD had significant effects on the QTVI-Tei index, and age had significant effect on PWD-Tei index. Multivariate regression analysis revealed both QTVI-Tei index and PWD-Tei index were significantly affected by age.Conclusions:(1)QTVI velocity parameters and QTVI-Tei index developed with age in childhood, and it developed most rapidly during the infant period. This study established the normal values of QTVI velocity parameters of tricuspid annulus and RV Tei index in children. (2)There was asymmetry in the tricuspid annular motion. The AAP attachment might be an appropriate point to study the motion of tricuspid annulus because it had the fastest velocity, and it was easy to acquire; furthermore, it was not influenced by mitral annulus and septum.(3)QTVI velocity parameters can distinguish between systolic and diastolic function. Tei index is a feasible approach to assess global RV function. We suggest using QTVI velocity parameters together with Tei index to assess RV function in children.