Larsson Matilda, Bjällmark Anna, Lind Britta, Balzano Rita, Peolsson Michael, Winter Reidar, Brodin Lars-Ake
School of Technology and Health, Royal Institute of Technology (KTH), Huddinge, Sweden.
Heart Vessels. 2009 Sep;24(5):357-65. doi: 10.1007/s00380-008-1112-3. Epub 2009 Sep 27.
Wave intensity analysis is a concept providing information about the interaction of the heart and the vascular system. Originally, the technique was invasive. Since then new noninvasive methods have been developed. A recently developed ultrasound technique to estimate tissue motion and deformation is speckle-tracking echocardiography. Speckle tracking-based techniques allow for accurate measurement of movement and deformation variables in the arterial wall in both the radial and the longitudinal direction. The aim of this study was to test if speckle tracking-derived deformation data could be used as input for wave intensity calculations. The new concept was to approximate changes of flow and pressure by deformation changes of the arterial wall in longitudinal and radial directions. Flow changes (dU/dt) were approximated by strain rate (sr, 1/s) of the arterial wall in the longitudinal direction, whereas pressure changes (dP/dt) were approximated by sign reversed strain rate (1/s) in the arterial wall in the radial direction. To validate the new concept, a comparison between the newly developed Wave Intensity Wall Analysis (WIWA) algorithm and a commonly used and validated wave intensity system (SSD-5500, Aloka, Tokyo, Japan) was performed. The studied population consisted of ten healthy individuals (three women, seven men) and ten patients (all men) with coronary artery disease. The present validation study indicates that the mechanical properties of the arterial wall, as measured by a speckle tracking-based technique are a possible input for wave intensity calculations. The study demonstrates good visual agreement between the two systems and the time interval between the two positive peaks (W1-W2) measured by the Aloka system and the WIWA system correlated for the total group (r = 0.595, P < 0.001). The correlation for the diseased subgroup was r = 0.797, P < 0.001 and for the healthy subgroup no significant correlation was found (P > 0.05). The results of the study indicate that the mechanical properties of the arterial wall could be used as input for wave intensity calculations. The WIWA concept is a promising new method that potentially provides several advantages over earlier wave intensity methods, but it still has limitations and needs further refinement and larger studies to find the optimal clinical use.
波强度分析是一种能提供有关心脏与血管系统相互作用信息的概念。最初，该技术是有创的。从那时起，新的无创方法得以开发。一种最近开发的用于估计组织运动和变形的超声技术是散斑追踪超声心动图。基于散斑追踪的技术能够精确测量动脉壁在径向和纵向方向上的运动和变形变量。本研究的目的是测试散斑追踪得出的变形数据是否可作为波强度计算的输入。新的概念是通过动脉壁在纵向和径向方向上的变形变化来近似血流和压力的变化。血流变化（dU/dt）通过动脉壁纵向方向的应变率（sr，1/s）来近似，而压力变化（dP/dt）通过动脉壁径向方向的符号反转应变率（1/s）来近似。为验证这一新概念，对新开发的波强度壁分析（WIWA）算法与一种常用且经过验证的波强度系统（SSD - 5500，日本东京阿洛卡公司）进行了比较。研究人群包括10名健康个体（3名女性，7名男性）和10名冠心病患者（均为男性）。目前的验证研究表明，通过基于散斑追踪的技术测量的动脉壁力学特性可能是波强度计算的一个输入。该研究表明两个系统之间在视觉上具有良好的一致性，并且阿洛卡系统和WIWA系统测量的两个正向峰值（W1 - W2）之间的时间间隔在总体组中具有相关性（r = 0.595，P < 0.001）。患病亚组的相关性为r = 0.797，P < 0.001，而健康亚组未发现显著相关性（P > 0.05）。研究结果表明动脉壁的力学特性可作为波强度计算的输入。WIWA概念是一种有前景的新方法，可能比早期的波强度方法具有多个优势，但它仍然存在局限性，需要进一步完善和进行更大规模的研究以找到最佳临床应用。
