Finally there's the augmented vector foot, or aVF, on the left foot which anatomically isn't straight down, but it's close enough that it ends up representing the vector facing straight down on the diagram.

最后还有位于左腿的左下肢加压导联（aVF），解剖学上来讲它不是竖直向下的，但因为它非常接近竖直方向，最终代表了心电图上竖直向下的向量。