Sometimes premature atrial contractions can keep happening rather than being isolated events.

有时房性期前收缩会持续发生，而不是孤立的事件。

Typically treatment for premature atrial contractions isn't required.

通常房性期前收缩并不需要治疗。

They were measuring two things: the number of what are called premature atrial contractions and premature ventricular contractions.

房性早搏和室性早搏的数量。

This system transmits electricity along a precisely-timed pathway that ends with atrial and ventricular contractions — also known as heart beats.

这个系统通过精确定时的途径传输电流，以心房和心室收缩结束——也称为心跳。

They found that drinking coffee did not result in more premature atrial contractions — the early heart beats associated with atrial fibrillation.

他们发现，喝咖啡并没有导致更多的房性早搏——与房颤相关的心脏过早搏动。

The number of flutter waves preceding a QRS complex corresponds to number of atrial contractions to one ventricular contraction.

一个QRS波群前的房扑波的数目，相当于一次心室收缩对应的心房收缩的数目。

Alright, as a quick recap - A premature atrial contraction is when the atria contract too early because of a depolarization from an ectopic focus.

好，快速总结一下：房性期前收缩是指心房因为来自异位起搏点的除极化而过早地收缩。

Premature atrial contractions are diagnosed with an ECG which shows an early and abnormal looking P-wave and a potential QRS that may go along with it.

房性期前收缩可通过心电图诊断，一般是出现一个提前的形状异常的P波，以及一个可能伴随出现的QRS波。

If the heart is beating fast enough, the p-wave from the premature atrial contraction might happen at the same time as the t-wave from the previous, normal contraction.

如果心脏搏动得足够快，心房期前收缩的P波可能会和之前正常收缩的T波同时发生。

It's very common for everyone to have an early beat arising from the upper chambers of the heart called premature atrial contractions, or PACs, once in a while.

每个人的上心室偶尔都会出现早搏即房性早搏（PACs），这是非常常见的。

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。

On an electrocardiogram, the P-wave corresponds to atrial contraction, the PR interval corresponds to the slight delay through the AV node, and the QRS complex is ventricular contraction.

在心电图里，P波表示心房收缩，PR间期表示房室结的延搁，QRS波代表心室的收缩。

If the premature atrial contractions keep happening or cause palpitations, they can be treated with beta blockers or calcium channel blockers, both of which prevent the heart from beating too strongly.

如果房性期前收缩持续发生，或是导致心悸，可以用beta受体阻滞剂或钙通道阻滞剂治疗，这两种药物都可防止心脏过于强力地搏动。

When a premature atrial contraction consistently comes after each normal cardiac cycle, it's called atrial bigeminy and when one consistently comes after every two normal cardiac cycles, it's called atrial trigeminy.

当一个房性期前收缩总是紧接着每一个正常心动周期而来时，它被称为二联律；当一个房性期前收缩总是紧接着每两个正常心动周期而来时，它被称为三联律。

Initially, the blood flows passively into the ventricles, but near the end when there's just a bit left, there's an atrial contraction that gives the blood an extra hard push to help get it out.

起初，这些血被动流入心室；但当快结束，心房还剩一点血时，心房收缩一下，把血液再用力推出心房。

For symptoms, most people with premature atrial contractions don't actually notice them, but if they keep occurring they can cause lightheadedness due to less blood being delivered to the brain and they might also feel palpitations.

对于症状，大部分存在房性期前收缩的人并不能注意到它们，但是如果它们持续发生，会导致更少的血液被输送到大脑，产生眩晕感，也可能会感到心悸。

Oxygenated blood returns to the heart by way of pulmonary veins, which empty into the left atrium. Atrial contractions force blood from the left atrium through the mitral valve, also called bicuspid valve, into the left ventricle.

当心室收缩时，左室内血液经主动脉瓣流入主动脉¬----人体最大的动脉，为全身组织供血。