1967 Volume 5 Issue 5 Pages 364-375
A new type of analog computer, specially designed for the analysis of spatial vectorcardiograms, were introduced. This “spatial magnitude, velocity and acceleration electrocardiograph” can compute the following calculations automatically, using VCG leads as input :
Spatial magnitude ECG=√X2+Y2+Z2
Spatial velocity ECG=_??_
Spatial acceleration ECG=_??_Electrical characteristics of the differential, the squaring, the extracting and the rectifying circuits were excellent.
Spatial magnitude, velocity or acceleration ECG under normal and various pathologic conditions showed the corresponding characteristic patterns. Spatial magnitude ECG was considered as the expression of spatial magnitude of the cardiac vectors on linear time scale. Spatial velocity ECG expressed the rate of change of arc length of spatial vector loop. Acceleration ECG was considered to express the rate of change of the velocity of inscription of spatial vector loop. The velocity or acceleration ECG could not be considered to express the velocity or acceleration of the impulse transmission within the heart directly, although considered to be closely related with them. “coronary T waves” are regarded as the expression of the abnormality of velocity of T loop.
Delayed velocity or acceleration of initial QRS vector was frequently observed in cases of myocardial infarction, and leads to correct diagnosis in cases in which standard ECG were equivocal. In more than 50% of cases of myocardial infarction where the T waves of standard ECG returned to normal, abnormalities of T waves of spatial velocity ECG were observed.
