A low-distortion filter method to reject muscle noise in multi-lead electrocardiogram systems.

This paper proposes a low-distortion filter method for rejection of muscle noise in multilead electrocardiogram (ECG) systems. This approach combines low-pass filtering with a modified version of source consistency filtering. The low-pass filtering splits the raw ECG signal into a muscle-noise-free part and a muscle-noise-overlapping part. The modified source consistency filtering then extracts the signal components from the muscle-noise-overlapping part. The extracted signal components are restored to the muscle-noise-free part as the output. The performance of our method was verified with simulated and clinically recorded ECG signals. The simulated ECG signals were created from computer simulation using three-dimensional, realistically shaped heart and torso models. The ideal signals are superimposed with white noise to simulate muscle noise and with a low frequency sine wave to simulate baseline drift. For verification, our method was compared with Butterworth low-pass filters. The results show that our method can effectively reduce muscle noise with less distortion of the QRS wave than conventional low-pass filters.

A study on home health care support information system for health evaluation.

The need for home health care has been increasing in Japan and the application of various techniques such as medical informatics are desired to support home health care services. Therefore, we developed an information system for health evaluation of the elderly including patients at home by applying multifunctional telephone set and an IC memory card, by which complaints, symptoms, and conditions by them can be collected, recorded, and transmitted to medical facilities. We also conducted an experiment for trial use of the system with the cooperation of elderly female volunteers. It was recognized that the elderly volunteers could operate the system with the help of public health nurses and their health information could be collected by the system. Although the developed system has some problems, it was suggested that the system would be useful for the support of health evaluation of elderly at home.

Comparative simulation of excitation and body surface electrocardiogram with isotropic and anisotropic computer heart models.

Comparative simulations between isotropic and anisotropic computer heart models were conducted to study the effects of myocardial anisotropy on the excitation process of the heart and on body surface electrocardiogram. The isotropic heart model includes atria, ventricles, and a special conduction system, and is electrophysiologically specified by parameters relative to action potential, conduction velocity, automaticity, and pacing. The anisotropic heart model was created by incorporating rotating fiber directions into the ventricles of the isotropic heart model. The orientation of the myocardial fibers in the ventricles of the model was gradually rotated counterclockwise from the epicardial layer to the endocardial layer for a total rotation of 90 degrees. The anisotropy of conduction velocity and intracellular electric conductivity was included in the simulation. Comparative simulations of the normal heart, LBBB, and RBBB showed no significant differences between the two models in the excitation processes of the whole heart or in the body surface electrocardiograms. However, it was easier to induce ventricular fibrillation in the anisotropic model than in the isotropic model. The comparative simulation is useful for investigating the effects of myocardial anisotropy at the whole heart level and for evaluating limitations of the isotropic heart model.

A study on the development of a filing system for funduscopic images with a personal computer for Twin AMHTS.

A filing system for ocular funduscopic image data was developed by using a personal computer for the Twin AMHTS. The development of the system was tried as one of the data transfer system including image data between two similar AMHTSs named the Twin AMHTS through the information network system. The filing system is capable of storing 26782 data of ophthalmoscopic pictures with a data compression mode by using a magneto-optical disk (MOD) whose storage capacity of both sides is 616 MB. It takes no long time for retrieval and display of the image data in the filing system. Good quality of compression and decompression obtained and reproducibility of the ocular fundus picture is favorable regardless of normal or abnormal cases. As a result, it is suggested that the developed system has practical utility although it requires more improvement.