This is what leads to a premature ventricular contraction, or PVC.

这就导致了一次室性期前收缩，或者说PVC。

Premature ventricular contractions are early beats that arise from the lower chambers of the heart.

室性早搏是指从心脏下心室产生的早搏。

Now - in both these situations, the QRS complex comes in early, which means an early ventricular contraction.

现在，在这两种情况下，QRS波群都会提前出现，意味着一次提前的心室收缩。

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。

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

有时室性期前收缩会持续发生，而不是孤立事件。

For example, ventricular bigeminy is when a premature ventricular contraction consistently comes after each normal cardiac cycle.

比如，室性二联律就是室性期前收缩在每个正常心动周期之后持续发生。

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。

The ventricular contraction is seen as a QRS complex, and the ventricular repolarization, and therefore it's relaxation, is seen as a T-wave.

心室收缩以QRS复合波群的形式展现，心室复极以及因此发生舒张的波形，则视为T波。

What ends up happening here is there's this big long pause between ventricular contractions, greater than the sinus interval.

最后发生的是在心室收缩之间有一个长间歇，比窦性间歇更长。

Then there's the other kind of irregular heartbeat: Premature ventricular contractions are early beats that arise from the lower chambers of the heart.

还有另一种不规则的心跳: 室性期前收缩是由心脏下腔(左右心室)引起的早期心跳。

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。

Regardless of the originating ventricle, a premature ventricular contraction often has an abnormal T wave since the timing and direction of repolarization will be abnormal as well.

不论起源心室是哪个，室性期前收缩由于去极化的时程和方向也会异常，而经常有一个异常的T波。

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。

And they do that because your ventricles contract to build up pressure and pump blood out of the heart. This high pressure caused by ventricular contraction is called systole.

它们这样做是因为你的心室收缩以增加压力并将血液泵出心脏。这种由心室收缩引起的高压称为心脏收缩。

And there are two tricks to a good ventricular contraction. One, the ventricles are so large that the signal has to be distributed evenly to ensure a coordinated contraction.

良好的心室收缩有两个技巧。第一，心室太大，信号必须均匀分布，以确保协调收缩。

The blood flow starts small, rises to a maximum in mid-systole at the peak of ventricular contraction, then attenuates toward the end of systole.

血流一开始很小，在收缩中期，即心室收缩的最高峰，达到最大值，然后逐渐减弱直到收缩期结束。

For diagnosis, sometimes an electrocardiogram or ECG can be helpful, and people will often have low-amplitude signals, and smaller QRS complexes, due to restricted ventricular contraction.

对于诊断，有时心电图会很有用，病人通常会有低峰信号，或者更小的QRS波，这是由于被限制的心室收缩。

Alright, as a quick recap - Premature ventricular contractions are abnormal heartbeats that originate in the ventricles, and show up as tall and wide QRS complexes on an ECG.

好，作一个小结：室性期前收缩是一种异常的心搏，起源于心室，在心电图上表现出高而宽的QRS波群。

Now, most people with premature ventricular contractions don't notice them, but if they keep occurring they can cause lightheadedness because of less blood getting delivered to the brain.

好，大部分有室性期前收缩的人不会注意到它们，但是如果他们持续发生，会导致头晕，因为被输送到脑部的血液变少。

The force of ventricular contraction starts a wave of increased pressure which begins at the heart and travels along the arteries. This wave is called the pulse.

可于相对靠近体表的动脉处摸到脉搏，尤其是当动脉可被按压于骨上时。