Background

Left atrial (LA) longitudinal strain is a novel parameter used for the evaluation of LA function, with demonstrated prognostic value in several cardiac diseases. However, the extent of load dependency of LA strain is not well known. The aim of this study was to evaluate the impact of acute changes in preload on LA strain, side by side with LA volume, in normal subjects.

Methods

Twenty-five healthy volunteers (13 men; mean age, 31 ± 2 years) were prospectively enrolled, who underwent two-dimensional and three-dimensional echocardiographic imaging during acute stepwise reductions in preload using a tilt maneuver: baseline at 0°, followed by 40° and 80°. Left ventricular and LA size and function parameters were measured using standard methodology, and LA strain-time curves were obtained using speckle-tracking software (TomTec), resulting in reservoir, conduit, and contractile strain components. All parameters were compared among the three loading conditions using one-way analysis of variance for repeated measurements.

Results

Although there were no significant changes in blood pressure, heart rate increased significantly with tilt. As expected, LA volumes, left ventricular volumes, and left ventricular ejection fraction, as well as E wave, A wave, and e′ significantly decreased with progressive inclination. In parallel, LA reservoir, conduit, and contractile strain values decreased with reduction in preload (reservoir: 42.9 ± 3.9% to 27.5 ± 3.8%, P < .001; conduit: 29.3 ± 2.7% to 20.2 ± 5.0%, P < .001; contractile: 13.6 ± 2.9% to 7.3 ± 3.5%, P < .001). Paired post hoc analysis showed that all LA strain values were significantly different among all three tilt phases. Of note, percentage change in LA reservoir strain was significantly smaller than that in LA maximum volume.

Conclusions

In normal subjects, LA strain is preload dependent but to a lesser degree than LA volume. This difference underscores the relative advantage of LA strain over maximum volume, when LA assessment is used as part of the diagnostic paradigm.

中文翻译：

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正常受试者左心房负荷的负荷依赖性

背景

左心房（LA）纵向应变是用于评估LA功能的新参数，在多种心脏疾病中具有预后价值。然而，LA应变的载荷依赖性程度尚不为人所知。这项研究的目的是评估正常受试者中预紧力的急性变化对LA菌株的影响，并与LA容量并列。

方法

前瞻性招募了25名健康志愿者（13名男性，平均年龄31±2岁），他们在通过倾斜操作逐步降低预负荷期间接受了二维和三维超声心动图成像：基线为0°，然后是40°和80°。使用标准方法测量左心室和LA的大小和功能参数，并使用斑点跟踪软件（TomTec）获得LA应变时间曲线，从而产生储层，导管和收缩应变成分。使用单向方差分析对三种负载条件下的所有参数进行比较以进行重复测量。

结果

尽管血压没有明显变化，但心率随倾斜而显着增加。正如预期的那样，LA容积，左心室容积和左心室射血分数以及E波，A波和e'随着进行性倾斜而显着降低。同时，LA储层，导管和收缩应变值随预载的减少而降低（储层：42.9±3.9％至27.5±3.8％，P  <.001；导管：29.3±2.7％至20.2±5.0％，P  <。 001；收缩性：13.6±2.9％至7.3±3.5％，P  ＜.001）。配对事后分析显示，所有三个倾斜阶段之间的所有LA应变值均显着不同。值得注意的是，LA储层应变的百分比变化明显小于LA最大体积的变化。

结论

在正常受试者中，LA应变与预紧力有关，但程度小于LA量。当将LA评估用作诊断范例的一部分时，这种差异强调了LA菌株相对于最大体积的相对优势。