The Normal Vectorcardiogram and a System for the Classification of Vectorcardiographic Abnormalities

Abstract

The essentially 3-dimensional nature of the spatial vectorcardiogram (sVCG) requires that it be studied as a vector sequence in space, and not merely in its projections on the arbitrary frontal, sagittal, and transverse planes. One striking characteristic of the normal QRS st-loop is that it lies approximately in a single "plane of predilection," which does not coincide with any of these 3 arbitrary planes. This paper describes the variations observed in the sVCG, recorded by a cubical lead system, with particular reference to the "QRS plane," in a group of normal subjects and suggests a system for classifying abnormalities of the sVCG, based on the QRS plane.

Characteristics of the Frequency Spectrum in the Normal Electrocardiogram and in Subjects Following Myocardial Infarction

“…7 ' 8 Scalar leads reflect the projection of this loop. The 3 scalar limb leads of largest amplitude and those recorded from the left precordium usually exhibit smooth R waves.…”

An evaluation of planarity of the spatial QRS loop by three dimensional vectorcardiography: Its emergence and loss

“…The possibility that this apparent planarity is an artifact imposed by the conducting materials between the heart and electrodes was also excluded by Milnor [3]. Observations on the isolated rabbit heart in a homogeneous fluid medium showed that the preferred QRS plane is still present under such conditions.…”

“…As Milnor pointed out [3], the fact that the normal spatial QRS loop lies approximately in a single plane is rather surprising. When the complex structure of the ventricular musculature is considered together with the numerous possible pathways along which the depolarization impulse passes, it is a rather striking observation that the termini of the successive instantaneous vectors should lie in a single plane.…”

“…There are a number of reports in the literature [1][2][3][4][5][6][7][8][9][10][11][12][13][14] suggesting that the QRS complex of the three-dimensional spatial VCG loop is essentially planar in normal persons.…”

“…Rochet and Vastesaeger [2] confirmed andextended this observation, reporting the variations of normality. Milnor [3]introduced quantitative expression to the QRS plane by means of the panoramic vectorcardiogram. Frank (1956) also observed that normal vectorcardiographic loops are found to lie essentially in a plane, the ratio of maximum length to maximum width-viewed-edgewise usually being at least 10:1 in normal persons [4].…”