高血压患者的扭转和心肌应变与左心室射血分数的关系。
Relation of torsion and myocardial strains to LV ejection fraction in hypertension.
机构信息
Division of Cardiovascular Medicine, Department of Medicine, University of Alabama at Birmingham, 1530 3rd Avenue South, Birmingham, AL 35294, USA.
出版信息
JACC Cardiovasc Imaging. 2012 Mar;5(3):273-81. doi: 10.1016/j.jcmg.2011.11.013.
OBJECTIVES
The goal of this study was to define the mechanism of preserved ejection fraction (EF) despite depressed myocardial strains in hypertension (HTN).
BACKGROUND
Concentric left ventricular (LV) remodeling in HTN may have normal or supranormal EF despite depressed myocardial strains. The reason for such discordance is not clear. The aim of this study was to comprehensively evaluate the LV mechanics in a well-defined HTN population to define underlying reasons for such a paradox.
METHODS
Sixty-seven patients with resistant HTN and 45 healthy control subjects were studied by cardiac magnetic resonance imaging and tissue tagging with 3-dimensional analysis. Amplitude and directional vector of longitudinal (Ell), circumferential (Ecc), and principal strain for maximal shortening (E3) were computed at basal, mid, and distal LV levels, respectively. LV torsion, defined as the rotation angle of apex relative to base, and LV twist, which accounts for the effects of differential LV remodeling on torsion for comparison among the 2 groups, were also calculated.
RESULTS
LV mass index and LV mass/LV end-diastolic volume ratio were significantly higher in the HTN group compared with controls, consistent with concentric LV remodeling. Ell and Ecc were significantly decreased in amplitude with altered directional vector in HTN compared with controls. However, the amplitude of E3 was similar in the 2 groups. Torsion and twist were significantly higher in HTN, which was mainly due to increase in apical rotation. The HTN group demonstrated significantly increased LV wall thickening compared with controls that resulted in greater LVEF in the HTN group compared with controls (70% vs. 65%, p < 0.001, respectively).
CONCLUSIONS
In compensated LV remodeling secondary to HTN, there is increased LV wall thickening with preserved E3 and increased torsion compared with normal controls. This, therefore, contributes to supranormal LVEF in HTN despite depressed longitudinal and circumferential strains.
目的
本研究旨在确定高血压（HTN）患者射血分数保留（EF）但心肌应变压低的机制。
背景
HTN 中的同心性左心室（LV）重构可能具有正常或超正常的 EF，尽管心肌应变压低。这种不和谐的原因尚不清楚。本研究的目的是全面评估明确的 HTN 人群的 LV 力学，以确定这种悖论的潜在原因。
方法
对 67 例难治性 HTN 患者和 45 例健康对照者进行心脏磁共振成像和组织标记的 3 维分析。分别在 LV 基底、中部和远端计算纵向（Ell）、环向（Ecc）和最大缩短的主应变（E3）的幅度和方向向量。LV 扭转定义为心尖相对于基底的旋转角度，LV 扭结考虑了 LV 重塑的差异对两组之间扭转的影响，也进行了计算。
结果
与对照组相比，HTN 组的 LV 质量指数和 LV 质量/LV 舒张末期容积比显著升高，符合同心性 LV 重构。与对照组相比，HTN 组 Ell 和 Ecc 的幅度明显降低，方向向量发生改变。然而，两组的 E3 幅度相似。HTN 组的扭转和扭结明显升高，主要是由于心尖旋转增加。与对照组相比，HTN 组的 LV 壁增厚明显增加，导致 HTN 组的 LVEF 明显高于对照组（分别为 70%和 65%，p<0.001）。
结论
在 HTN 引起的代偿性 LV 重构中，与正常对照组相比，LV 壁增厚增加，E3 增加，扭转增加。因此，这导致 HTN 中存在超正常的 LVEF，尽管存在纵向和环向应变压低。
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