When that depolarization wave from an atrial ectopic focus gets to the AV node, there are a couple options.

当除极波从房性异位起搏点到达房室结，它有许多选择可做。

Similarly, each of the limb leads produces its own viewpoint of the depolarization wave as well.

同样地，每一个肢体导联也在用不同的角度去记录除极波。

An ECG tracing specifically shows how the depolarization wave during each heartbeat - which is a wave of positive charge.

心电图描记明确显示了除极波在每次心跳中是怎样运动的；除极波是一种正电荷的波。

A reentrant loop basically starts sending out depolarization waves to the rest of the heart tissue each time the wave goes around.

每沿着折返环路环绕一圈，它就开始向其余心肌组织发放除极波。

Now, lead V1 on an ECG measures a depolarization wave that moves towards the right ventricle.

好，心电图的导联V1测量向右心室传导的除极波。

These can appear lots of different ways depending on where the two depolarization waves meet each other.

这会以许多不同方式出现，取决于两个除极波相遇的地点。

As an example, consider how the 6 chest leads - V1 through V6 - register this depolarization wave form called the QRS complex.

作为例子，我们来看一下这6个胸导联，V1-V6是怎样来记录被称为“QRS波群”的除极波形的。

In this situation, the depolarization wave conducts down the left bundle branch and then through the ventricles aberrantly, resulting in an abnormally wide QRS complex.

在这种情况下，除极波向下传导到左束支，然后异常地穿过心室，导致一个异常增宽的QRS波群。

So, in short, a particularly stressed out atrial cell or a reentrant loop can send out depolarization waves that contract the atria, and result in an early, or premature, atrial contraction.

因此，简单说就是一个尤其应激的心房细胞、或者一个折返环路发放除极波导致心房收缩，造成早期或过早的心房收缩。

In fact, if there's a depolarization wave that goes straight up, which is perpendicular to the positive and negative electrodes, then there'd be no deflection at all!

事实上，如果有一个除极波是竖直向上的，即完全垂直于正、负电极的话，那么心电图上就不会显示任何波形。

Another scenario, though, is if a depolarization wave from an atrial ectopic focus gets through the AV node but get sent through the ventricles abnormally like when a bundle branch is in refractory.

另一种情况，如果从房性异位起搏点来的除极波通过了房室结，但却在一个异常的时间到达心室，比如当一个束支处于不应期。

The ECG tracing shows a depolarization wave moving towards an electrode as a positive deflection, and one moving away as a negative deflection, each of which is proportional to the size of the dipole.

在心电图上，向正电极移动的除极波显示为正向的波形（向上的偏转），远离正电极的则显示为负向的波形（向下的偏转），波形的大小与双极子（电压差值）的大小成正比。

Now even though it'd be nice if the depolarization wave lined up perfectly with the electrodes, usually that's not the case, so what we end up looking at is the vector component that is parallel to the electrode.

现在，如果除极波和电极的方向平行，那非常理想，但通常情况并非如此，所以我们最终关注的其实是平行于电极的向量分量。

Now, though, let's say you have a ventricular ectopic focus somewhere in the ventricles, which is a cell or area of tissue that sends off an early depolarization wave, before even the SA node gets to fire.

现在假设你在心室某处有一个异位起搏点，就是一个发放提前除极波的细胞或组织区域，甚至在窦房结开始放电之前。

Next, the ectopic beat could happen during the PR segment, and because the ectopic depolarization happens relatively slowly, oftentimes, it will combine with the normal depolarization wave coming down the ventricular conduction system, resulting in a ventricular fusion beat.

其次，异位心搏可能发生在PR间期，因为异位去极化相对缓慢，它常会和在心室传导系统中下行的正常除极波融合，导致室性融合心搏。