Okuma K
Am Heart J. 1976 Oct;92(4):473-80. doi: 10.1016/s0002-8703(76)80047-6.
ECG and VCG changes in QRS configuration before and after left anterior subdivision block (LASB), isolated and combined with right bundle branch block (LASB combined with RBBB), were studied in canine hearts. In another series left posterior subdivision block (LPSB), isolated and combined with right bundle branch block (LPSB combined with RBBB), were also performed. With LASB, the A QRS axis deviated superiorly to the left and the QRS duration showed no significant prolongation. Additional RBBB to the existing LASB, moreover, rotated the A QRS axis counterclockwise, and prolonged the QRS duration significantly. With LPSB, the axis was deviated inferiorly to the right and the QRS duration showed no significant prolongation. Additional RBBB to the existing LPSB rotated the A QRS axis clockwise. The QRS duration showed significant prolongation. Vectorcardiographically, the initial part of the QRS loop did not show any essential changes with either LASB or LPSB. The main and terminal parts of the QRS loop, however, were deviated superiorly and to the left with LASB and inferiorly and to the right with LPSB. No changes were observed in the direction of rotation of QRS loop with either subdivision block. From these results it appears that the changes in the terminal forces are more of importance than the initial forces in the diagnosis of hemiblock.
在犬心研究了左前分支阻滞（LASB）前后、单独及合并右束支阻滞（LASB合并RBBB）时QRS波群形态的心电图（ECG）和向量心电图（VCG）变化。在另一组实验中，也进行了左后分支阻滞（LPSB），单独及合并右束支阻滞（LPSB合并RBBB）。发生LASB时，平均QRS电轴向左上偏移，QRS时限无明显延长。在已有LASB基础上合并RBBB，则使平均QRS电轴逆时针旋转，并使QRS时限明显延长。发生LPSB时，电轴向右下偏移，QRS时限无明显延长。在已有LPSB基础上合并RBBB使平均QRS电轴顺时针旋转，QRS时限明显延长。向量心电图显示，LASB和LPSB时QRS环的起始部分均无本质改变。然而，LASB时QRS环的主体和终末部分向左上偏移，LPSB时向右下偏移。两种分支阻滞时QRS环的旋转方向均无改变。从这些结果看来，在半阻滞的诊断中，终末向量的改变比起始向量的改变更为重要。
