If an atrial cell outside of the SA node initiates a depolarization, it's called an atrial ectopic focus.

如果一个窦房结以外的心房细胞引发了一个除极，这个心房细胞被称为房性异位起搏点。

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。

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。