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背景心房压力超负荷所致胶原重构,尤其是胶原纤维的异质性分布是心房颤动发生的重要原因之一,但目前尚未见到对此病理生理过程进行定量分析的报道。目的尝试建立一种能够对心房胶原纤维二维分布情况进行定量描述的方法。方法采用兔腹主动脉肾上段缩窄方法建立左心室压力超负荷模型;按照狭窄程度不同,分为假手术组(无狭窄,n=14),左室肥厚组(50%～60%狭窄,n=16)和心力衰竭组(70%～80%狭窄,n=12)。术后8周,对存活动物(心力衰竭组死亡5只,其余各组无死亡)通过心脏超声、有创血流动力学检测对左心室和左心房结构和功能进行评价。心肌组织胶原分析采用苦味酸天狼猩红染色。利用具有自动角度识别功能的Continuity软件结合圆分布统计分析,对心房胶原纤维的二维分布进行定量分析。采用的圆分布变量为两类,一类为反映胶原纤维角度向量圆分布集中趋势的参数(平均向量长度和集中参数),另一类为反映胶原纤维圆分布离散趋势的参数(圆分布方差和圆分布标准差)。结果腹主动脉肾上段缩窄为50%～60%可形成明显的左心室肥厚及左心房扩大和心房肌细胞肥大;缩窄为70%～80%时,产生明显左心功能衰竭,伴有左心房内径明显增大[(14.7±3.1)vs(6.5±0.9)mm,P<0.01]。压力超负荷左心功能处于代偿期时,左心房胶原纤维平均向量长度、集中参数、圆分布方差和标准差均与假手术组无统计学差异,提示左心功能代偿期时心房胶原分布的异质性并未明显增强;当左心功能失代偿并且心房出现明显扩大时,左心房胶原纤维平均向量长度和集中参数明显降低,而圆分布方差和标准差增大,提示压力超负荷伴左心房明显扩大时心房胶原分布异质性增强。结论由左心房压力超负荷引起的心房胶原纤维二维分布异质性增高的现象,能够采用自动角度识别结合圆分布统计分析进行定量描述。
BackgroundAtrial pressure overload caused by collagen remodeling, especially the heterogeneous distribution of collagen fibers is one of the important causes of atrial fibrillation, but so far no quantitative analysis of the pathophysiological process has been reported. Objective To establish a method that can quantitatively describe the two-dimensional distribution of atrial collagen fibers. Methods The model of left ventricular hypertrophy was established by the method of narrowing the upper abdominal aorta in rabbits. According to the degree of stenosis, the rats were divided into sham operation group (no stenosis, n = 14), left ventricular hypertrophy group (50% -60% stenosis, n = 16) and heart failure group (70% -80% stenosis, n = 12). Eight weeks after surgery, left ventricular and left atrium structures and functions were assessed by echocardiography and invasive hemodynamic tests on 5 surviving animals (5 in the heart failure group and none in the rest). Myocardial collagen analysis using picric acid Sirius red staining. Continuity software with automatic angle recognition and circular distribution statistical analysis were used to quantitatively analyze the two-dimensional distribution of atrial collagen fibers. There are two types of circular distribution variables, one is the parameter (average vector length and concentration parameter) that reflects the central tendency of the circular distribution of collagen fiber angle angle, and the other is the parameter that reflects the discrete tendency of the circular distribution of collagen fiber Standard deviation of circular distribution). Results Abdominal aorta renal narrowing of 50% to 60% of the formation of significant left ventricular hypertrophy and left atrium enlargement and atrial myocyte hypertrophy; narrowing of 70% to 80%, produced significant left ventricular failure, with The diameter of the left atrium was significantly increased [(14.7 ± 3.1) vs (6.5 ± 0.9) mm, P <0.01]. Pressure overload Left ventricular function in the compensatory phase, left atrial collagen average vector length, concentration parameters, circular distribution of variance and standard deviation were not statistically different from the sham operation group, suggesting that the left ventricular function compensatory atrial collagen distribution Of the heterogeneity did not significantly increase; when left ventricular dysfunction and atrial enlargement significantly, the average length and concentration parameters of left atrial collagen fibers decreased significantly, while the circular distribution of variance and standard deviation increased, suggesting that the pressure overload With atrial enlargement of the left atrium significantly increased heterogeneity of atrial collagen distribution. Conclusion The heterogeneity of two-dimensional distribution of atrial collagen fibers caused by left atrial pressure overload can be quantitatively described by using automatic angle recognition and circular distribution statistical analysis.