不同起搏频率对心肌应变的影响

Evaluation of myocardial strain at different pacing rates

目的探讨心率对心肌应变的影响。方法选择20例已植入起搏器的病窦综合征患者。利用常规超声心动图和二维斑点追踪显像技术,测心房起搏频率60,70,80,90和100次/分下每搏输出量和纵向、径向和环状方向上左室18节段收缩期应变峰值并计算心输出量和整体纵向、径向和环状应变峰值。结果随着起搏频率的增加,每搏输出量和左室各节段、各水平及整体在不同方向上的应变峰值递减,心输出量逐渐递增。起搏频率60,70和80次/分时,整体纵向应变峰值分别为-24.58%±10.19%、-23.13%±11.36%和-20.20%±9.48%(P>0.05);而起搏频率90和100次/分时整体纵向应变峰值分别为-15.56%±8.89%(P<0.05)和-9.80%±6.01%(P<0.001)。起搏频率60,70和80次/分时,整体径向应变峰值分别为33.40%±9.81%、31.92%±10.69%和28.84%±10.58%(P>0.05);而起搏频率90和100次/分时整体径向应变峰值分别为23.34%±8.17%(P<0.05)和15.77%±7.42%(P<0.001)。起搏频率60,70和80次/分时,整体环状应变峰值分别为-21.43%±8.48%、-20.23%±7.10%和-17.65%±7.25%(P>0.05);而起搏频率90和100次/分时整体环状应变峰值分别为-13.65%±5.27%(P<0.01)和-8.23%±3.72%(P<0.001)。结论随起搏频率增加,左室各方向应变下降。心率对应变的影响为负性。

Objective To investigate the effects of different heart rate on strain by speckle-tracking imaging speckle- tracking imaging（STI）. Methods Colour doppler images and STI was performed in 20 patients with bipolar DDD pace- makers for sick sinus syndrome. Stroke volume（SV） and left ventricular（LV） peak systolic longitudinal, radial and circum- ferential strain were measured at 60, 70, 80, 90 and 100 beats/min, which was controlled by atrial pacing and atrioventric- ular delay and cardiac output and global strain were calculated. Results There was a significant decrease in SV and LV peak systolic longitudinal, radial and circumferential strain when the pacing rate increased from 60 to 100 beats/min, how- ever the cardiac output increased. The LV peak systolic longitudinal global strain values at 60,70, and 80 beats/min were - 24.58% -＋10.19% ,-23.13% ＋11.36% and -20.20% ＋9.48% respectively （ P〉0.05 ） ,while at 90 and 100 beats/min were -15.56% ＋8.89% （ P〈0.05 ） and -9.80% ＋6.01% （ P〈O. 001 ）. The LV peak systolic radial global strain val- ues at 60,70, and 80 beats/min were 33.40% ±9.81%, 31.92% ± 10.69%, and 28.84% ± 10.58% respectively （ P〉0. 05 ）, while at 90 and 100 beats/min were 23.34% ±8.17% （ P〈0.05 ） and 15.77%±7.42% （ P〈0. 001 ）. The LV peak systolic circumferential global strain values at 60,70, and 80 beats/min were - 21.43 % ± 8.48 %, - 20.23 % ± 7. 10% and -17.65% ±7.25% respectively （ P〉0.05 ）, while at 90 and 100 beats/min were -13.65% ±5.27% （ P〈 0.01 ） and -8.23% ±3.72% （ P〈0.001 ）. Conclusions LV peak systolic longitudinal, radial and circumferentialstrain decreased in parallel with the increasing of heart rate. STI could be used to evaluate the strain at different heart rate.