多普勒超声测定左心室Max（dp／dt）的新方法

心室内压力变化率峰值Ｍａｘ（ｄｐ／ｄｔ）是一项评价心肌收缩功能的重要指标。但其测定常需借助于心导管术，临床应用受到限制。依据流体力学基本定律，本文提出：等容收缩期内表现为压力的势能将在射血期部分地转化为以１／２ｐＶ２为形式的动能，因而势能的最大变化率Ｍａｘ（ｄｐ／ｄｔ）将在动能的最大变化率Ｍａｘ（ｄｋ／ｄｔ）上得到反映。应用特制计算机软件将主动脉血流速度曲线转化为４Ｖ２曲线，该曲线的一级导数峰值即为Ｍａｘ（ｄｋ／ｄｔ）。应用脉冲多普勒超声测定２３例先天性心脏病患儿的主动脉血流频谱参数并与心导管测定的左心室Ｍａｘ（ｄｐ／ｄｔ）进行对比分析。结果显示：主动脉血流频谱参数Ｍａｘ（ｄｋ／ｄｔ）与左心室Ｍａｘ（ｄｐ／ｄｔ）呈良好相关（ｒ＝０．８１７，Ｐ＜０．００１），直线回归方程为：Ｍａｘ（ｄｐ／ｄｔ）＝０．４７Ｍａｘ（ｄｋ／ｄｔ）＋６７．９（Ｋｐａ／ｓ），平均加速度ｍＡ及Ｖｐ２／ＡＴ与Ｍａｘ（ｄｐ／ｄｔ）亦有较好的相关性。表明由多普勒超声获得的主动脉血流频谱参数Ｍａｘ（ｄｋ／ｄｔ）能较准确地估侧左室Ｍａｘ（ｄｐ／ｄｔ），因而可作为评价心脏收缩功能的可靠指标

A New Ultrasound Method for Estimation of Left Ventricular Max(dp/dt)

Max(dp/dt)is an important index for assessing ventricular contractility.Unforunately,clinical application of max(dp/dt)has been limited by the fact that its measurement generally requres cardiac catheterization.According to the hydrodynamic law,we hypothesize the potential energy manifested as intravenrtacular pressure during isovolumetric systolic period is partially converted to the kinetic energy expressed as 1/2p V 2 in ejection time,therefore ,the peak rate of kinetic energy change,max(dk/dt),should reflect the maximum rate of potential energy,max(dp/dt).Following this assumption with customized computer software the aortic flow profile was digitized and converted to 4V 2 curve whose maximum value of the first derivative is termed as max(dk/dt). In 23 patients with congenital heart defect,aortic flow indices measured with pulse wave Doppler echocardiography were compared with left ventricular max(dp/dt)obtanied by cardiac catheterization.The results show that aortic flow index max(dk/dt)correlated very well with left ventricular max(dp/dt).The linear regresstin equation was as follows:Max(dp/dt)=0 47Max(dk/dt) 67 9(KPa/s)(r=0 817,P<0 001).A fair correlation of max(dp/dt)with mA and Vp 2/AT was also found.It is concluded that Doppler derived aortic index max(dk/dt)could be used to estimate LV max(dp/dt).Thus,Max(dk/dt)may be a reliable index of contractile state.