Ishikawa K
Chest. 1976 Jun;69(6):762-8. doi: 10.1378/chest.69.6.762.
The net effect of intracavitary blood mass on cardiac dipole is believed to augment its radial components and reduce the tangential components. Commonly known as the Brody effect, it results from the lower resistivity of intracavitary blood mass as compared to the surrounding tissues (the short-circuiting effect). Thus, an increase in hematocrit should reduce and a decrease in hematocrit augment the Brody effect. It has generally been assumed that the initial portion of the process of ventricular depolarization and the left maximal spatial vector (LMSV) represent the radial components, while the terminal portion of the process of ventricular depolarization and the right maximal spatial vector (RMSV) represents the tangential components of cardiac dipole. Furthermore, the atrial accession is believed to be tangential. Based on this Brody effect, it is anticipated that an improvement of anemia, as indicated by an increase in hematocrit, would tend to reduce the initial portion of the QRS, and LMSV, but enhance the terminal portion of the QRS, and the P-wave amplitude; however, the results of this study were not in agreement with such predictions. With an improvement of anemia, a significant number of cases showed no essential changes in these electrocardiographic factors or even showed reactions oppisite to the Brody effect. This probably indicates that there are many other factors which might modify the Brody effect.
心腔内血液团块对心脏电偶极的净效应被认为会增强其径向分量并减少切向分量。这通常被称为布罗迪效应，它是由于心腔内血液团块的电阻率低于周围组织（短路效应）所致。因此，血细胞比容增加应会减弱布罗迪效应，而血细胞比容降低则会增强该效应。一般认为，心室去极化过程的起始部分和左最大空间向量（LMSV）代表径向分量，而心室去极化过程的终末部分和右最大空间向量（RMSV）代表心脏电偶极的切向分量。此外，心房附加波被认为是切向的。基于这种布罗迪效应，预计血细胞比容增加所表明的贫血改善会倾向于减少QRS波群的起始部分和LMSV，但会增强QRS波群的终末部分和P波振幅；然而，本研究结果与这些预测不一致。随着贫血的改善，相当数量的病例在这些心电图因素上没有本质变化，甚至出现了与布罗迪效应相反的反应。这可能表明还有许多其他因素可能会改变布罗迪效应。
