Toshiyuki Furukawa

Computer simulation of cardiac arrhythmias

A mathematical model of the cardiac conduction system has been developed. The mechanisms of cardiac arrhythmias are described mathematically, and the heart is modeled as a network, where each element is defined by a unique set of time parameters from the action potential. The mathematical description is separated from the network structure, thus making it possible to run the model with different network sizes. Simulated ECG curves are produced in each case. This model is especially suited for rhythm studies, and a variety of different cardiac arrhythmia mechanisms has been simulated such as reentry, reflection, modulated parasystole, and different kinds of block.

Optimal control of medical treatment: Adaptive control of blood glucose level in diabetic coma

Abstract The primary purpose of clinical decision-making is to determine the most adequate treatment for individual pathological conditions, and the process of diagnosis and treatment constitutes a feedback loop. The present study was undertaken to apply “optimal control theory” to this process of clinical decision-making. The basic requirements for the application of optimal control theory in the clinical setting is presented and a clinical application, “adaptive control program,” is proposed for the control of blood glucose level in diabetic coma using a simulation model of blood glucose kinetics.

Body surface potential mapping system equipped with a microprocessor for the dynamic observation of potential patterns

A body surface potential mapping system equipped with a microprocessor has been developed. It enables high-speed real-time and simultaneous observation of e.c.g. data of 96 lead points in a character display mode. The machine has functions not only to perform basic data processing such as baseline correction and linear interpolation for malfunctioned electrodes but also to generate an isopotential contour map, record data onto a floppy disc, make hard copies of displayed patterns and characters, etc. To increase the operation speed, all the assembler programs were put in one module. Thus, an operator can easily recognise the spatial motion pattern of the body surface potential map and, in addition, find malfunctioned channels by observing the pattern. A belt type electrode system allows quick and adaptable attachment. The practical usefulness of the system has been proved with the co-operation of cardiologists with over 120 cases of cardiac disease.

3-D mapping of body surface potentials.

A new system has been developed in which the human body surface potentials are displayed in a 3-dimensional format using computer graphics. A wire-frame model of the human torso is constructed using geometrical data from several cross-sectional slices. The body surface potentials are measured and the isopotential lines drawn. By mapping the co-ordinates obtained with the isopotential line subroutine to the X, Y and Z torso arrays, a 3-dimensional representation of the depolarization wave travelling across the body surface can be displayed. The deviations from its normal path are clearly seen in the 2 clinical cardiac conditions presented (right bundle branch block and left ventricular premature beat). The increased realism and spatial resolution, as compared to ECG and the 2-dimensional contour map, lead to a clear understanding and interpretation of the underlying electrical phenomena of the heart while making a diagnosis or presenting experimental results.