Riordan Matt M, Kovács Sándor J
Department of Biomedical Engineering, School of Engineering and Applied Science, Washington University, St. Louis, Missouri, USA.
Am J Physiol Heart Circ Physiol. 2007 Jun;292(6):H2952-8. doi: 10.1152/ajpheart.01356.2006. Epub 2007 Feb 16.
Although Doppler tissue imaging frequently indicates the presence of mitral annular oscillations (MAO) following the E' wave (E'' wave, etc.), only recently was it shown that annular "ringing" follows the rules of damped harmonic oscillatory motion. Oscillatory model-based analysis of E' and E'' waves provides longitudinal left ventricular (LV) stiffness (k'), relaxation/viscoelasticity (c'), and stored elastic strain (x(o)') parameters. We tested the hypothesis that presence (MAO(+)) vs. absence (MAO(-)) of diastolic MAO is an index of superior LV relaxation by analyzing simultaneous echocardiographic-hemodynamic data from 35 MAO(+) and 20 MAO(-) normal ejection fraction (EF) subjects undergoing cardiac catheterization. Echocardiographic annular motion and transmitral flow data were analyzed with a previously validated kinematic model of filling. Invasive and noninvasive diastolic function (DF) indexes differentiated between MAO(+) and MAO(-) groups. Specifically, the MAO(+) group had a shorter time constant of isovolumic relaxation [tau; 51 (SD 13) vs. 67 (SD 27) ms; P<0.01] and isovolumic relaxation time [63 (SD 16) vs. 82 (SD 17) ms; P<0.001] and greater ratio of peak E-wave to peak A-wave velocity [1.19 (SD 0.31) vs. 0.97 (SD 0.31); P<0.05]. The MAO(+) group had greater peak lateral mitral annulus velocity [E'; 17.5 (SD 3.1) vs. 13.5 (SD 3.8) cm/s; P<0.001] and LVEF [71.2 (SD 7.5)% vs. 65.4 (SD 9.1)%; P<0.05] and lower heart rate [65 (SD 9) vs. 74 (SD 9) beats/min, P<0.001]. Additional conventional and kinematic modeling-derived indexes were highly concordant with these findings. We conclude that absence of early diastolic MAO is an easily discernible marker for relaxation-related diastolic dysfunction. Quantitation of MAO via stiffness and relaxation/viscoelasticity parameters facilitates quantitative assessment of regional (i.e., longitudinal) DF and may improve diagnosis of diastolic dysfunction.
尽管组织多普勒成像常常显示在E'波（E''波等）之后存在二尖瓣环振荡（MAO），但直到最近才发现环的“振铃”遵循阻尼简谐振动的规律。基于振荡模型对E'波和E''波进行分析可得出左心室（LV）纵向硬度（k'）、舒张/粘弹性（c'）以及储存的弹性应变（x(o)'）参数。我们通过分析35例存在舒张期MAO（MAO(+)）和20例不存在舒张期MAO（MAO(-)）且射血分数正常（EF）的受试者在进行心导管检查时的同步超声心动图-血流动力学数据，来验证舒张期MAO的存在（MAO(+)）与不存在（MAO(-)）是左心室舒张功能较好的一个指标这一假设。采用先前验证过的充盈运动学模型对超声心动图的瓣环运动和二尖瓣血流数据进行分析。有创和无创舒张功能（DF）指标在MAO(+)组和MAO(-)组之间存在差异。具体而言，MAO(+)组等容舒张时间常数较短[τ；51（标准差13）对67（标准差27）毫秒；P<0.01]以及等容舒张时间较短[63（标准差16）对82（标准差17）毫秒；P<0.001]，且E波峰值与A波峰值速度之比更大[1.19（标准差0.31）对0.97（标准差0.31）；P<0.05]。MAO(+)组二尖瓣环侧壁峰值速度更高[E'；17.5（标准差3.1）对13.5（标准差3.8）厘米/秒；P<0.001]、左心室射血分数更高[71.2（标准差7.5）%对65.4（标准差9.1）%；P<0.05]且心率更低[65（标准差9）对74（标准差9）次/分钟，P<0.001]。其他传统指标和运动学模型得出的指标与这些发现高度一致。我们得出结论，舒张早期MAO的缺失是舒张功能障碍相关舒张功能异常的一个易于识别的标志。通过硬度和舒张/粘弹性参数对MAO进行定量有助于对局部（即纵向）DF进行定量评估，并可能改善舒张功能障碍的诊断。
