The spatial orientation of the plane including the mean QRS and T vector of the normal electrocardiogram.

T HERE is some evidence1' 2 that the spatial angle between the mean QRS and T vector might serve as an important criterion for the diagnosis of ventricular hypertrophy or coronary insufficiency, although the angle was not actually measured. Recently, a method has been described' to construct and measure this angle from the conventional electrocardiogram. With this method, a vector is defined in terms of its direction in the horizontal plane (H'), its vertical angle (V0, elevation), and its magnitude. The method is simple; the measurement of a vector can be completed within three minutes or less. For some purposes, at least, it may be desirable to analyze not only the spatial angle between the mean QRS and T vector, but also the spatial orientation of the plane included by these vectors. The present report indicates the findings in exploratory studies.