Abstract
A new multipurpose analog system has been developed, which can compute the following formula automatically and record the spatial magnitude ECG, spatial velocity ECG, spatial acceleration ECG, spatial circumference ECG and polarcardiogram very easily and quickly, using the scalar ECG (X, Y, Z) of vectorcardiographic lead as inputs.
Spatial magnitude ECG=√X2+ Y2+ Z2
Spatial velocity ECG=√ (dX/dt) 2+√ (dY/dt) 2+ (dZ/dt) 2Spatial acceleration ECG =√ (d2 X/dt2) 2+ (d2Y/dt2) 2+ (d2Z/dt2) 2
Spatial circumference ECG=∫√ (dX/dt) 2+ (dY/dt) 2+ (dZ/dt) 2·dt
Time constants for the differentiating circuits were 1 msec, 5 msec and 10 msec for QRS, P and T waves respectively. Vector sum circuits applying absolute value operation introduced by Imai and Nguyen Phuoc (1972) were used in this system instead of the squaring, adding and square root circuits, and simplification of the composition of the system and the highly reliable records were obtained. Computations of the orientation curve of the polar ECG were performed following the Dower's method, and the longitude ECG (α, β and γ) and the latitude ECG (P-A, I-S and R-L)
