Studies on vectorcardiography

To elucidate the cause of high degree left axis deviation (LAD) revealed in ECG, 86 subjects in total, 60 males and 26 females, whose ECG indicated a QRS-interval less than 0.12 sec and a mean QRS electrical axis in-between -30° to -90°, were selected for analysis of VCG. Lead systems of VCG introduced by Frank and Kimura were employed for this study.As described in preceeding paper, the Kimura lead system is considered to be useful for the analysis of LAD since in experiments of human torso models, this system was demonstrated to have a value in use to detect vertical changes of heart-electromotive-forces. Then, by the analysis of configurations of QRS-loop in the frontal plane of VCG, they were divided as follows; in the Frank lead system: 6 types, F-1 to F-6, in the Kimura lead system: 5 types, CCW(L), CCW(R), CCW(R'), CW(L), CW(R). In the latter, they were furthermore sub-divided into 3 types, a, b, and c, according to the length of the vertical component of QRS-loop. (See the text, Fig. 1 and Fig. 2)Results were as follows: 1) F-4 and F-5 types which are considered to represent the left anterior hemiblock (LAH) in the Frank lead system showed CCW(L) type, left superiorly deviated QRS-loop with elongation, in the Kimura lead system. 2) The SI SII SIII type in the ECG was determined to corespond to F-1, F-2, or F-6 type in the Frank lead system, and to CCW(R), CCW(R'), or CW(R) type in the Kimura lead system in which the right component of QRS-loop was dominant. 3) Several cases classified as F-3 or F-6 type in the Frank lead system which could not be defined as LAH were determined as CCW(L)a type in the Kimura lead system suggesting the LAH. 4) There could not be found correlations between Rosenbaum's diagnostic criteria for LAH and these VCG configurations. Therefore, it was suggested by the present study that the analysis of VCG configurations are useful for the diagnosis of LAH. 5) VCGs of ostium primum atrial septal defect were classified as F-6 and CCW(R') types whose configurations of QRS-loop were different from the one of LAH. 6) Several cases of pulmonary emphysema associating with LAD were disclosed to be classified as F-4 and CCW(L)a types suggesting the LAH.