title: [Geographical distribution of left ventricular Tei index based on principal component analysis].
abstract: OBJECTIVE
  To provide a scientific standard of left ventricular Tei index for healthy people from various region of China, and to lay a reliable foundation for the evaluation of left ventricular diastolic and systolic function.
  
  
  METHODS
  The correlation and principal component analysis were used to explore the left ventricular Tei index, which based on the data of 3 562 samples from 50 regions of China by means of literature retrieval. Th e nine geographical factors were longitude(X₁), latitude(X₂), altitude(X₃), annual sunshine hours (X₄), the annual average temperature (X₅), annual average relative humidity (X₆), annual precipitation (X₇), annual temperature range (X₈) and annual average wind speed (X₉). ArcGIS soft ware was applied to calculate the spatial distribution regularities of left ventricular Tei index.
  
  
  RESULTS
  There is a significant correlation between the healthy people's left ventricular Tei index and geographical factors, and the correlation coefficients were -0.107 (r₁), -0.301 (r₂), -0.029 (r₃), -0.277 (r₄), -0.256(r₅), -0.289(r₆), -0.320(r₇), -0.310 (r₈) and -0.117 (r₉), respectively. A linear equation between the Tei index and the geographical factor was obtained by regression analysis based on the three extracting principal components. The geographical distribution tendency chart for healthy people's left Tei index was fitted out by the ArcGIS spatial interpolation analysis.
  
  
  CONCLUSIONS
  The geographical distribution for left ventricular Tei index in China follows certain pattern. The reference value in North is higher than that in South, while the value in East is higher than that in West.
authors.affiliation: Institute of Health Geography, College of Tourist and Environment Science, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Xu
authors.forename: Miao
authors.initials: M
authors.lastname: Ge
authors.forename: Jinwei
authors.initials: J
authors.lastname: He
authors.forename: Ranyin
authors.initials: R
authors.lastname: Xue
authors.forename: Shaofang
authors.initials: S
authors.lastname: Yang
authors.forename: Jilin
authors.initials: J
authors.lastname: Jiang
mesh_terms: D002681:China; D003971:Diastole; D005843:Geography; D006352:Heart Ventricles; D006801:Humans; D025341:Principal Component Analysis; D012016:Reference Values; D012044:Regression Analysis; D013599:Systole; D016276:Ventricular Function