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Biomedical subjects

M Okajima

Publications and source records attributed to M Okajima.

At least 73 records · Page 4Linked to original sources
PubMed1981

On current topics and future prospects in electrocardiography.

Some selected topics and future prospects in electrocardiography were stated, namely, electrocardiograph, computer interpretation of electrocardiogram, body surface mapping and electrocardiography at large. Special attention was paid to computer application to signal processing and decision making with respect to electrocardiography. A brief review for inverse problem in electrocardiography was made as well. In regard to body surface mapping, another way of expression of the maps was proposed where, instead of routine isopotential map, isochrone map for ventricular activation time of QRS complexes was used for representing the ventricular electrophysiologic activities.

Computers↗
PubMed1980

Perthes' disease--a classification based on the extent of epiphyseal and metaphyseal involvement.

A tentative classification of Perthes' disease according to the extent of epiphyseal and metaphyseal involvement in lateral radiographs of the hip was applied to 61 hips in 55 patients. Forty-four hips were treated by containment (Tachjian's trilateral socket hip abduction orthosis) and 17 hips were treated surgically either by intertrochanteric or sub-trochanteric osteotomy. The results correlated well with the classification of the authors. The greater the extent of involvement of the epiphysis and metaphysis, the severer the resulting deformity. The choice of method of treatment is also discussed. It is concluded that this classification may be of prognostic value and may be useful to differentiate atypical cases.

Child↗
PubMed1980

The body surface isopotential maps of the non-transmural infarctions--a simulation study of excitation spread in a ventricular model.

Simulation by a digital computer of excitation spread in a human ventricular model produced displays of body surface isopotential maps. Localization of model myocardial infarctions to non-transmural and transmural sites produced distinctive differences in these displayed isopotential maps. The body surface directly over the infarcted lesion was negative in potential only in the first half period of the QRS complex and then became positive. The model demonstrated that this later positive potential was due to delayed arrival of excitation to the subepicardial layer outside of the subendocardial lesion. While, in transmural infarction, the overlying body surface remained negative in potential throughout the QRS complex. It is expected that body surface isopotential maps will become clinically available and will permit helpful differential diagnoses between non-transumral and transmural myocardial infarctions.

Computers↗
PubMed1979

[ECG data base].

Explore the source record for details and available documents.

Aged↗
PubMed1978

Computational reconstruction of body surfact isopotential maps in myocardial infarction: comparison between nontransmural and transmural infarction.

The relationship between the lack of electromotive force in myocardial infarction and body surface potential distribution was investigated on maps reconstructed from a simulated heart model and transfer impedance vectors of human torso model. The heart model, a cluster of 3-mm cubic blocks, was stored in the memory of a computer. Transfer impedance vectors between 81 lead points on the human torso model and 392 positions covering ventricular areas in the torso were measure. Body surface potential values were calculated mathematically by summing up scalar products between the electromotive force of the heart model and the measured transfer impedance vectors. Thus, reconstructed maps changed in their patterns with the alternation in lacation and/or extent of infarcted region in the heart model. In particular, the appearance of the abnormal potential minimum, which projects the infarcted region in the heart model onto the torso surface, was characteristic in both transmural and subendocardial infarction. In addition, delayed activation in the intact layer of the epicardium overlying the infarcted region produced a potential maximum on the same place as the abnormal potential minimum appeared previously.

Action Potentials↗
PubMed1976

Atrial T (Ta) loop in dogs with or without atrial injury.

In 46 dogs with experimentally produced complete A-V block, the P and the Ta waves before and after the atrial injury were recorded in scalar orthogonal ECG leads at high speed and high amplification. The P and the Ta loops were drawn by hand from the scalar ECG'S. In the dogs without atrial injury, the maximum Ta vector was oriented to the right, superiorly and anteriorly. The P-T angle was close to 180 degrees in each of the three planes. The magnitude of the maximum Ta vector was nearly proportionate to that of the maximum P vector in each plane. The Ta loop was a smooth, elongated ellipse in configuration and showed clockwise rotation in all planes, as did the P loop. The spatial atrial gradient obtained from the scalar ECG was small. In the dogs with atrial injury, the Ta loop changed in direction, configuration, and inscription direction. The P-Ta angle and the relative magnitude of the maximum Ta vector to that of the maximum P vector changed markedly. The change of the P loop remained minimum. The maximum Ta vector and spatial atrial gradient were oriented toward the atrial injury site. The magnitude of the spatial atrial gradient was extremely large after injury. These findings were thought to be important in suggesting the presence of atrial injury and its localization.

Animals↗
PubMed1976

Atrial T (Ta) loop in patients with A-V block: a trial to differentiate normal and abnoral groups.

The P and the Ta waves were recorded with high fidelity and high amplification. The P and the Ta loops were constructed from these waves. Human subjects with A-V block were used, so that the Ta waves could be completely visualized. Subjects were separated into two groups: one group with minimal clinical evidence of heart disease and another with more severe disease. There were great and important differences in the Ta loops between the two groups with minimal differences in the P loops. In the patients with minimal heart disease, the Ta loop was always oriented to the right and superiorly. The P-Ta angle was approximately 180 degrees and all patients in this group showed a small spatial atrial gradient oriented to the left and inferiorly. These findings are similar to those found in normal dogs reported separately in the Journal. In the group of four patients with more severe heart disease, the P-Ta angle varied widely and deviated greatly form 180 degree. The satial atrial gradient was very large in three cases. The findings and others such as the direction of the maximum Ta vectors were diagnostically useful in separating the Ta loops of the two patient groups. Results indicate that the Ta loop may be very useful in separating normal from diseased atria in individuals with A-V block. There are some frequency differences between the Ta wave and the QRS complex. If the Ta wave could be extracted from the QRS complex by the use of some kind of filter when A-V block dose not exist, most of the Ta wave could be visualized. This, along with high fidelity recording techniques, may help detect atrial abnormalities in patients without A-V block. Future development of this equipment as a clinical tool is hoped for.

Aged↗