BACKGROUND The three-dimensional rearrangement of the right ventricular (RV) myocardium during cardiac deformation is unknown. Previous in-vivo studies have shown that myocardial left ventricular (LV) deformation is driven by rearrangement of aggregations of cardiomyocytes that can be characterised by changes in the so-called E3-angle. Ex-vivo imaging offers superior spatial resolution compared with in-vivo measurements, and can thus provide novel insight into the deformation of the myocardial microstructure in both ventricles. This study sought to describe the dynamic changes of the orientations of the cardiomyocytes in both ventricles brought upon by cardiac contraction, with particular interest in the thin-walled RV, which has not previously been described in terms of its micro-architecture. METHODS The hearts of 14 healthy 20 kg swine were excised and preserved in either a relaxed state or a contracted state. Myocardial architecture was assessed and compared between the two contractional states by quantification of the helical, transmural and E3-angles of the cardiomyocytes using high-resolution diffusion tensor imaging. RESULTS The differences between the two states of contraction were most pronounced in the endocardium where the E3-angle decreased from 78.6° to 24.8° in the LV and from 82.6° to 68.6° in the RV. No significant change in neither the helical nor the transmural angle was found in the cardiomyocytes of the RV. In the endocardium of the LV, however, the helical angle increased from 35.4° to 47.8° and the transmural angle increased from 3.1° to 10.4°. CONCLUSION The entire myocardium rearranges through the cardiac cycle with the change in the orientation of the aggregations of cardiomyocytes being the predominant mediator of myocardial wall thickening. Interestingly, differences also exist between the RV and LV, which helps in the explanation of the different physiological capabilities of the ventricles.

中文翻译：

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解决心脏收缩引起的自然心肌重塑；对猪左心室和右心室进行离体心血管磁共振研究。


背景技术心脏变形过程中右心室（RV）心肌的三维重排尚不清楚。先前的体内研究表明，心肌左心室 (LV) 变形是由心肌细胞聚集的重新排列驱动的，其特征在于所谓的 E3 角的变化。与体内测量相比，体外成像提供了卓越的空间分辨率，因此可以提供对两个心室心肌微观结构变形的新见解。这项研究试图描述心脏收缩引起的两个心室中心肌细胞方向的动态变化，特别是对薄壁右心室特别感兴趣，此前从未对其微结构进行过描述。方法健康猪14头，体重20kg，摘除心脏，在松弛状态和收缩状态下保存。通过使用高分辨率扩散张量成像量化心肌细胞的螺旋角、透壁角和 E3 角，评估和比较两种收缩状态下的心肌结构。结果 两种收缩状态之间的差异在心内膜中最为明显，其中左心室的 E3 角从 78.6° 减小到 24.8°，右心室的 E3 角从 82.6° 减小到 68.6°。 RV 心肌细胞的螺旋角和透壁角均未发现显着变化。然而，在左室心内膜中，螺旋角从 35.4° 增加到 47.8°，透壁角从 3.1° 增加到 10.4°。结论整个心肌在心动周期中发生重新排列，心肌细胞聚集方向的变化是心肌壁增厚的主要介质。 有趣的是，右心室和左心室之间也存在差异，这有助于解释心室的不同生理功能。