Akemi Takeuchi

Analysis of the T wave of the magnetocardiogram in patients with essential hypertension by means of isomagnetic and vector arrow maps

Magnetocardiograms (MCGs) of 50 normal subjects and 40 patients with essential hypertension were recorded to determine the value of the MCG for detecting abnormal repolarization. Among the patients with essential hypertension, there were nine cases (22.5%) in whom isopotential maps did not show rightward repolarization vectors but isomagnetic and vector arrow maps showed a rightward repolarization vector in some areas in addition to the normal repolarization vector. Departure maps of the ECG showed an increased repolarization vector directed anteriorly in some of these cases. The repolarization abnormality was recognized in only the MCG departure map in four cases, while no case showed abnormality in only the ECG departure map. With the progress of hypertension, the repolarization abnormality was seen more frequently and its detection using the MCG was higher than that using the ECG. Furthermore, multiple dipoles were detected more frequently from the MCG than from the ECG. Thus the MCG seems more useful than the ECG in the analysis of repolarization abnormalities in essential hypertension.

The P wave in the magnetocardiogram

The P wave of the magnetocardiogram (MCG) was investigated in normal subjects and in patients with right and left atrial overloading. In normal subjects, the MCG P wave was positive at right lower sternal sites and negative in the other portions. The current source deduced from the MCG and the isomagnetic map was directed inferiorly and to the left throughout the entire phase of atrial activation. In patients with right atrial overloading, the direction of the current source deduced from the MCG was similar to that of normal subjects, but its amplitude was significantly greater. In left atrial overloadings, a negative-positive biphasic P wave was seen more frequently than in normal subjects at left parasternal sites. In the late phase of atrial activation, the MCG could detect the two dipoles, i.e. one directed inferiorly and other directed to the left. These dipoles might correspond to right and left atrial activities, respectively. These results show that the MCG might add useful information on current source to the conventional electrocardiogram.

Detection of Accessory Pathway in Patients with WPW Syndrome by Means of The Isomagnetic Map and MRI

The current source is expected to be localized more exactly with a magnetocardiogram (MCG) than with an electrocardiogram (ECG). In the present study, the isomagnetic map at the time of the delta wave and a gated magnetic resonance imaging (MRI) were compared to assess the usefulness of the magnetocardiogram (McG) in localizing a position of the accessory pathway (Kent bundle). Spach and Benson reported that the analysis of the T wave was as useful as that of the QRS wave in predicton of the pre-excited sites of the ventricle. 1,2 Therefore, we examined the repolarization wave in order to localize the site of an accessory pathway in WPW syndrome, because the repolarization abnormality might be detected more precisely by the MCG. 3 Our results showed that the analysis of the repolarization wave’s of the MCG was as useful as the delta wave to detect the site of an accessory pathway.

The Magnetocardiogram in Patients with Systolic and Diastolic Overload of the Right Ventricle

The second derivative gradiometer is expected to detect the current source from the right ventricle more specifically, where it is located close to the anterior chest wall because of its unique system. Therefore, we investigated the magnetocardiogram (MCG) in patients with right ventricular overload (RVO), and correlated the MCG findings with hemodynamic parameters. This study was also aimed to diagnose RVO in the presence of right bundle branch block (RBBB), which so far has been considered to be difficult to diagnose by the conventional electrocardiogram (ECG).

Detection of the Abnormal Repolarization Vector in Diabetes Mellitus by Means of the Isomagnetic Map

The magnetocardiogram (MCG) recorded with the second-derivative SQUID gradiometer may be more useful to detect the current source parallel to the anterior chest wall and multiple current dioples than the electrocardiogram (ECG). We have already reported that the abnormal repolarization vector could be detected more frequently by the MCG than ECG in patient with left ventricular overloading and myocardial infarction. 1,2 In the present study, we investigated the clinical usefulness of the isomagnetic map analysis for the diagnosis of repolarization abnormality in diabetic patients.