BACKGROUND:About 50% patients with coronary heart disease have no symptoms of cardiac disease before the first onset of myocardial infarction. Therefore, it is of great importance to make early and accurate detection of coronary heart disease and myocardial ischemia.OBJECTIVE: To measure the time of heart repolarization with magnetocardiography and probe into the role of non-invasive magnetocardiographic examination in evaluating cardiac function in patients with coronary heart disease.DESIGN: Case-control observation.SETTING: Department of Cardiology of Philippustift Hospital, Essen,GermanyPARTICIPANTS: Totally 52 patients hospitalized for suspected coronary heart disease in the Department of Cardiology of Philippustift Hospital(Essen, Germany) between March 1998 and December 2002 were recruited,and another 10 patients diagnosed as old myocardial infarction were set as myocardial infarction group. Informed consents were obtained from the patients. Totally 32 healthy volunteers aged above 40 years old were recruited as the control group.METHODS: All the patients received the following examinations: physical and laboratory examinations, rest and stress electrocardiography(ECG), echocardiography, coronary artery angiography and magnetocardiography(MCG) examination. The control group received only rest ECG and MCG examination. The values of QT dispersion with ECG and MCG were compared between the patients and healthy controls. The diagnostic criteria for coronary heart disease: stenosis of one coronary artery ≥ 75% according to coronary artery angiography; index of repolarization time of the heart was measured with MCG QT dispersion and MCG dispersion coincidence (the mean of probe signal and QT dispersion of peripheral probe in each MCG).MAIN OUTCOME MEASURES: ECG QT dispersion, MCG QT dispersion as well as coincidence index of QT dispersion of the observed subjects in each group.RESULTS: The 52 patients with suspected coronary heart disease,10 with myocardial infarction, and 32 healthy controls all entered the result analysis. The patients with suspected coronary disease were divided into 2 groups: group with coronary heart disease (n=27) and group without coronary heart disease (n=25). [1] Comparison of ECG QT dispersion: there was no significant difference among the groups(P ＞ 0.05). [2] Comparison of MCG QT dispersion: MCG QT dispersion in myocardial infarction group was significantly higher than that in control group [81.3±21.5, 52.4±13.6 (F=13.113, P ＜ 0.05)]. [3]Comparison of coincidence index of QT dispersion: Coincidence index of QT dispersion in myocardial infarction group and coronary heart disease group was both significantly higher than that in control group [15.6±4.2, 14.9±4.1, 10.2±2.7 (F=2.403, 3.332, P ＜ 0.01)].CONCLUSION: Compared with ECG, MCG can better reflect changes in the repolarization process of patients with coronary heart disease,and coincidence index of dispersion is superior to QT dispersion. This is because MCG is more sensitive to tangential currents presented at the precardial region when myocardial ischemia and infarction occur.%背景:有近50%的冠心病患者在第1次发生心肌梗死前没有心脏病的征兆,因此尽早可靠地检测到冠心病、心肌缺血尤为重要.目的:采用心磁图对冠心病患者心脏复极时间变异进行测量,探讨无创的心磁图检查对冠心病患者心功能的评估作用.设计:病例-对照观察.单位:德国埃森Philippustift医院心内科.对象:选择1998-03/2002-12在德国埃森Philippustift医院心内科住院,怀疑为冠心病的患者52例,另选择10例确诊为陈旧性心肌梗死的患者作为心肌梗死组,以上患者均知情同意.对照组为32例年龄大于40岁的自愿参与观察的健康人.方法:所有患者均进行普通12导联的心电图、负荷心电图、超声心动图、冠状动脉造影检查、血生化检查及心磁图检查;对照组只行普通12导联心电图及心磁图检查,比较患者与对照组间心磁图、心电图QT离散度的变异程度.冠心病的诊断标准为冠状动脉造影检查发现冠状动脉有1支狭窄≥75%.对于心脏复极时间变异的指标,采用心磁图QT离散度及离散度均一性指数(每个心磁图探头信号与周围探头QT离散度的平均数)进行测量.主要观察指标:各组观察对象的心电图QT离散度、心磁图QT离散度及QT离散度均一性指数.结果:怀疑为冠心病的患者52例、陈旧性心肌梗死组10例及对照组32例全部进入结果分析.怀疑为冠心病的患者分为2组,冠心病组27例,无冠心病组25例.[1]心电图QT离散度的比较:各组差异无显著性意义(P＞0.05).[2]心磁图QT离散度的比较:心肌梗死组显著高于对照组[81.3±21.5,52.4±13.6(f=13.113,P＜0.05)].[3]QT离散度均一性指数的比较:心肌梗死组与冠心病组均显著高于对照组[15.6±4.2,14.9±4.1,10.2±2.7(f=2.403,3.332,P＜0.01)].结论:心磁图能更好地反映冠心病患者心脏复极时间均一性的变异,优于普通心电图,而离散度均一性指数优于QT离散度.因为心磁图对心切线电流更为敏感,而当心肌缺血、梗死时心肌电流在心前区表现为切线电流.
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