正常人群心磁图特征的探讨

Characteristics of magnetocardiography in healthy subjects

目的:采用无屏蔽式心磁图仪MCG-7,探讨我国正常人群的心磁图(MCG)特征,并比较不同年龄组间心磁图各指标是否存在差异。方法:采用德国Magscan公司生产的无屏蔽式MCG-7记录仪,选择平均分级(averageclassification of total maps,ACTM)、异常磁图比率(ratio of abnormal maps,RAM)、复合心室激动指数(complexventricular excitation index,CVEI)、R波与T波顶点的最大磁场值比值(R-max/T-max比值)、T波起始处电流密度最大电轴方向(Tbegin)、T波顶点处电流密度的最大电轴方向(T-max)来描述100例正常人心磁图结果。结果:正常人MCG在ST-T整个复极过程中存在双极对称结构,仅有一个主要电流方向,指向左下0°～90°,Tbegin在10°～25°之间,T-max在25°～35°之间。RAM为18%左右(9.10%～25.75%),ACTM平均值为2.36(2.10～2.50),CVEI平均值为18.68(-12.75～64.00),R-max/T-max比值为4.04(2.53～4.65)。各年龄组心磁图各项指标差异无统计学意义(P>0.05)。结论:心磁图是诊断心肌缺血的有用工具,正常人群不同年龄组间心磁图参数差异无统计学意义。

Objective To examine the parameters that quantify spatial and temporal aspects of cardiac magnetic signals in Chinese healthy individuals.Methods MCGs were registered at rest in 100 healthy subjects,aged（56±10）years（28-78 years）.MCG mapping was performed by MCG-7（MaGIC,Magscan GmbH） installed in an unshielded room.Six parameters including ACTM（average classification of total maps）,RAM（ratio of abnormal maps）,CVEI（complex ventricular excitation index）,R-max/T-max ratio,Tbegin（the max current density angle from T wave begins）and T-max（the max current density angle from T wave ends）were used for MCG analysis.Results During the whole repolarization period,most of the current density maps were characterized by two-dipole structure,the main direction of the vector pointed to a left-down direction at 0°-90°.The average angle of Tbegin pointed to 10°-25°,while T-max pointed to 25°-35°.The value of RAM was 18%（9.10%-25.75%）,ACTM was 2.36（2.10-2.50）,and CVEI was 18.68（-12.75-64.00）.No significant differences existed between various age groups（P0.05）.Conclusions MCG is a useful tool for the diagnosis of chronic myocardium ischemia.No significant differences existed in MCG parameters among various age groups in healthy volunteers.