Riordan Matt M, Kovács Sándor J
Department of Biomedical Engineering, Washington University, St. Louis, MO 63110, USA.
J Appl Physiol (1985). 2007 May;102(5):1862-70. doi: 10.1152/japplphysiol.01219.2006. Epub 2007 Jan 25.
Traditionally, global and longitudinal (i.e., regional) left ventricular (LV) diastolic function (DF) assessment has utilized features of transmitral Doppler E and A waves or Doppler tissue imaging (DTI)-derived mitral annular E' and A' waves, respectively. Quantitation of regional DF has included M-mode echocardiography-based approaches and strain and strain rate imaging (in selected imaging planes), while analysis of mitral annular "oscillations" has recently provided a new window into longitudinal (long-axis) function. The remaining major spatial degree of kinematic freedom during diastole, radial (short-axis) motion, has not been fully characterized, nor has it been exploited for its potential to provide radial LV stiffness (k'(rad)) and relaxation/damping (c'(rad)) indexes. Prior characterization of regional (longitudinal) DF used only annular E'- and A'-wave peak velocities or, alternatively, myocardial strain and strain rate. By kinematically modeling short-axis tissue motion as damped radial oscillation, we present a novel method of estimating k'(rad) and c'(rad) during early filling. As required by the (near) constant-volume property of the heart and tissue/blood incompressibility, in subjects (n = 10) with normal DF, we show that oscillation duration-determined longitudinal (k'(long) and c'(long)) and radial (k'(long) and c'(rad)) parameters are highly correlated (R = 0.69 and 0.92, respectively). Selected examples of diabetic and LV hypertrophic subjects yield radial (k'(long) and c'(rad)) parameters that differ substantially from controls. Results underscore the utility of the incompressibility-based causal relation between DTI-determined mitral annular long-axis (longitudinal mode) and short-axis (radial mode) oscillations in healthy subjects. Selected pathological examples provide mechanistic insight and illustrate the value and potential role of regional (longitudinal and radial) DF indexes in fully characterizing normal vs. impaired DF states.
传统上，整体和纵向（即局部）左心室舒张功能（DF）评估分别利用了经二尖瓣多普勒E波和A波的特征或多普勒组织成像（DTI）得出的二尖瓣环E'波和A'波的特征。局部DF的定量分析包括基于M型超声心动图的方法以及应变和应变率成像（在选定的成像平面中），而对二尖瓣环“振荡”的分析最近为纵向（长轴）功能提供了一个新的视角。舒张期剩余的主要运动自由度，即径向（短轴）运动，尚未得到充分表征，也未因其提供径向左心室僵硬度（k'(rad)）和松弛/阻尼（c'(rad)）指标的潜力而被利用。先前对局部（纵向）DF的表征仅使用二尖瓣环E'波和A'波的峰值速度，或者使用心肌应变和应变率。通过将短轴组织运动在运动学上建模为阻尼径向振荡，我们提出了一种在早期充盈期间估计k'(rad)和c'(rad)的新方法。根据心脏的（近乎）等容特性以及组织/血液不可压缩性的要求，在舒张功能正常的受试者（n = 10）中，我们表明由振荡持续时间确定的纵向（k'(long)和c'(long)）和径向（k'(long)和c'(rad)）参数高度相关（分别为R = 0.69和0.92）。糖尿病和左心室肥厚受试者的选定示例产生的径向（k'(long)和c'(rad)）参数与对照组有很大差异。结果强调了基于不可压缩性的因果关系在健康受试者中DTI确定的二尖瓣环长轴（纵向模式）和短轴（径向模式）振荡之间的实用性。选定的病理示例提供了机制性见解，并说明了局部（纵向和径向）DF指标在全面表征正常与受损舒张功能状态方面的价值和潜在作用。
