Blood is only expelled from the heart when it contracts.

心脏收缩时，血液才从心脏射出。

This is the term used to describe the contraction of the heart.

是用来描述心脏收缩的术语。

This is a term used to describe the contraction of the heart.

是一个用来描述心脏收缩的术语。

In other words, the contraction of the heart is shorter than the filling time.

换言之，心脏收缩比充盈时间短。

Also, though, the timing of the PAC will also determine how the heart contracts and therefore what the ECG looks like.

此外，房性期前收缩的时机也决定了心脏如何收缩以及因此产生的心电图形状。

That is reassuring. But what about the other bad beats, the premature contractions in the heart's lower chambers?

就让人放心了。有害心跳，发生在心脏下腔的期前收缩(室性期前收缩)呢?

The heart contracts and expands in a non-stop rhythm to push our blood around a system of arteries and veins.

心脏不间断地收缩和舒张，推动血液在动脉和静脉系统流动。

And this can quickly lead to cardiogenic shock, since the heart doesn't even have time to fill with blood before each contraction.

很快会导致心源性休克的发生，因为心脏在收缩之前还来不及充盈血液。

On rare occasions, a sudden change in heart rhythm prevents the upper chambers of the heart from contracting normally.

在极少数情况下，心律的突然变化会阻止心脏上腔的正常收缩。

It would squeeze the capsule tightly as the heart contracted and still keep a firm grip on it when the heart was relaxed.

它可以随着心脏的收缩轻微挤压胶囊，且在心脏放松时，也能紧紧抓住。

Cotton was the heartbeat of the section, the planting and the picking were the diastole and systole of the red earth.

棉花便是本地区的脉搏，植棉和摘棉便是红土心脏的舒张和收缩。

Now in addition to systolic heart failure, you've also got diastolic heart failure, which is where the heart's squeezing hard enough but not filling quite enough.

除收缩性心衰外，还有舒张性心力衰竭，指的是心脏收缩功能正常，但是在舒张期充盈受损。

Alright, so also the location of the ectopic focus in the atria determines how the heart contracts and therefore what the ECG looks like.

并且心房异位起搏点的位置决定了心脏如何收缩以及因此产生的心电图形状。

The current stops the irregular contractions of the cardiac muscle, and gives the heart a chance to start beating normally.

电流停止了肌肉的剧烈收缩 心脏，并让心脏有机会正常跳动。

If your heart has decreased contractility then it's going to have to work harder to maintain proper profusion of your body with blood.

如果心脏收缩力下降，么它将不得不更加努力地维持身体适当的血液灌注。

Frank and Starling were looking at the amount of blood in the heart before the ventricles contract.

Frank 和Starling正在观察心室收缩前心脏的血流量。

When your heart contracts, it's fair to think of it as your ventricles contracting, because they are the primary pumping chambers of your heart.

心脏收缩时，可以把它看作是心室收缩，因为它们是心脏的主要泵血室。

That being said, that contraction pumps the blood out the pulmonary valve, which just like the tricuspid valve has three cusps and also prevents blood from going backward.

也就是说，心脏收缩将血液泵出肺动脉瓣；与三尖瓣一样，肺动脉瓣也有三个尖瓣，也可防止血液倒流。

This ability is thanks to the intrinsic conduction system, which is the internal regulating system that causes the heart to contract rhythmically.

种能力是由于内在的传导系统，是导致心脏有节奏收缩的内部调节系统。

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.

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