| Budget Amount *help |
¥3,920,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥420,000)
Fiscal Year 2007: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2006: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
We investigated the issue of whether the current density map method, in which cardiac current is estimated from the magnetic gradient, facilitates the visualization of cardiac current undetectable by ECG.
1) Evaluation of an infarction vector
Old inferior myocardial infarctions (MI group) and normal healthy subjects (Normal group) were recorded using magnetocardiometer. The electromotive force of the heart was estimated from a current density map. In the current density map of the ventricular depolarization phase, multiple current densities were deduced from magnetocardiograms of the ventricular depolarization phase in the MI group, unlike normal subjects. In 4 patients in the MI group, multiple current sources were suggested, which were not detected in a body surface electrocardiogram. Magnetocardiogram is capable of permitting infarct electromotive forces to be detected, which could not be deduced from electrocardiography data.
2) Detection of cardiac current undetectable by electrocard
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iography using magnetocardiography in various cardiac diseases
The subjects were 50 healthy adults (N group), 40 patients with left ventricular overloading (LVO group), 15 patients with right ventricular overloading (RVO group), 10 patients with an old inferior myocardial infarction (OMI group), and 30 patients with diabetes mellitus (DM group). MCGs were recorded with a second derivative superconducting quantum interference device (SQUID) gradiometer using liquid helium. Isopotential maps and current density maps from unipolar precordial ECG leads and MCGs, respectively, were prepared, and the cardiac electric current was examined. The current density map at the ventricular depolarization phase showed one peak of current density in the N group. However, in the OMI group, the current density map showed multiple peaks of current density areas. In the RVO group, two peaks of current densities were detected at the right superior region and left thoracic region and these two diploles appeared to be from the right and left ventricular derived cardiac currents, respectively. Moreover, there was a significant correlation between the magnitude of the current density from the right ventricle and the systolic pulmonary arterial pressure. The current density map at the ventricular repolarization phase in the N group showed only a single current source. However, abnormal current sources in the current density maps were frequently detected even in patients showing no abnormalities on isopotential maps in the LVO, DM, and OMI groups.
Our results suggest that MCG with a current density map is useful for detecting cardiac current undetectable by ECG in an early stage. Less
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