论文摘要:
Objective To provide a new feasible and quantitative method for evaluating the severity of aortic regurgitation (AR), energy loss (EL) derived from vector flow mapping (VFM) and the diastolic retrograde time ration in the descending aorta of AR were studied.
Methods VFM were performed in 69 patients with normal left ventricular systolic function and different degrees of AR. According to the current guideline of semi-quantitative evaluation of the AR severity, the patients were divided into three groups: the mild AR, vena contracta (VC) <0.3 cm (Group A, n=27); the moderate AR, vena contracta 0.3-0.6 cm (Group B, n=20); the severe AR, vena contracta ≥0.6 cm (Group C, n=22). And they were compared with 30 normal persons (Group D). VFM, based on color Doppler superimposed on speckle tracking, allows acquisition of the blood flow velocities freely in any direction and calculation of the EL of the blood flow in chambers. The EL of diastolic retrograde flow in the descending aorta was calculated frame by frame in all groups. The color M-mode Doppler view of descending aortic reversal flow was obtained from the suprasternal imaging window, by placing a sample volume within the inner wall of descending aorta. RtR was calculated as: Reversal flow time ratio = reversal flow time (ms) /diastolic time (ms). All the values of the EL and RtR were averaged from three cardiac cycles. Statistical analyses were performed using SPSS 19.0(IBM Inc, Armonk, NY, USA). Continuous variables were expressed as mean ± SD and categorical variables were represented as percentages. Means between groups were compared by one-way ANOVA. Correlation analysis between variables was performed using Pearson correlation. P<0.05 was considered significant.
Results The mean value of EL increased accordingly with the grading of AR (1.87±1.15[J/(s*㎡)] for normal, 4.44±1.46[J/(s*㎡)] for mild AR, 6.78±1.85[J/(s*㎡)] for moderate AR and 15.22±5.34[J/(s*㎡)] for severe AR). RtR also showed an increase in relation to the degree of severity of AR (13.5±3.9% for normal, 20.6±5.2% for mild AR, 37.2±6.2% for moderate AR and 97.5±5.3% for severe AR). Close correlations were found between EL and VC (r=0.938, P <0.001) and jet width/LOVT ratio (r=0.848, P< 0.001). Good correlations were also found between RtR and VC (r=0.889, P <0.001) and jet width/LOVT ratio (r=0.899, P <0.001).
Conclusion EL in descending aorta by VFM in diastole may be a useful quantitative parameter to assess the severity of AR. RtR may be a new accurate quantitative parameter for AR quantitation.