Metastases to the myocardium are less common, but arise more commonly when cancer spreads via the blood.

然而转移到心并不是很常见，但是当癌细胞传播到血液中时，心癌的可能性将会升高。

Now, with coronary artery disease, there’s ischemia, or reduced blood flow to the region of myocardium supplied by that artery.

现在，冠状动脉性疾病患者存在心缺血，即由某一动脉供血的心血供减少了。

In this case, less blood and oxygen gets through the coronary artery to the heart tissue, which damages the myocardium.

在该情况下，冠状动脉没有给心脏供应足够的血液和氧气，进而导致心。

Over time, this results in maximal vasodilation beyond the obstruction, and it helps the collateral vessel redivert blood to the ischemic myocardium.

随着时的推移，这会使端的血管最大程度地扩张，并帮助侧支循环将血流引向缺血的心。

There's also a tiny third opening into the right atrium called the coronary sinus, which collects blood from coronary vessels returning from the myocardium.

右心房还有第三个微小的开口叫冠状窦，以收集从心返回的冠状静脉血液。

The end result is that blood is diverted, or stolen, away from the ischemic myocardium to non-ischemic areas, which further worsens the ischemia.

最终结果就是血液从缺血的心被转移或者说被“偷”到未缺血区域，进一步加剧了缺血。

As a result of ischemia, in the myocardium supplied by coronary artery B, the myocardial cells don’t receive enough oxygen, which is called hypoxia.

于是冠脉B供血的心出现了缺血，心细胞无法获得足够的氧气，称为“缺氧”。

This is a cross-section of the Chen-Lupino boy's myocardium.

这是Chen-Lupino心的横截面。

In severe cases, blood flow can been completely cut off, which results in myocardial infarction, or the necrosis of a portion of myocardium.

严重的情况下，血流会被完全断，引起心梗死，即心的部分坏死。

This is typically due to some kind of damage to the myocardium—or the heart muscle —which means it can’t contract as forcefully and pump blood as efficiently.

比较典型的是由于心，意味着心不能有力收缩，进而有效泵血。

If blood flow’s reduced or the myocardium is thicker, blood has a harder time reaching this deeper layer just under the endocardium, called the subendocardium.

一旦血流减少或心变厚，血流便难以到达最深层，即心内膜下层。

So, moving from the outside of the heart to the inside of the heart: after the epicardium, there's the myocardium, which is the muscular middle layer.

在心外膜后，有心层，即中的肉层。

It’s during these time of exertion or emotional stress that people with stable angina have chest pain, since the blood flow isn’t meeting the metabolic demands of the heart muscle, or myocardium.

稳定型心绞痛患者在劳累或情绪激动时会胸痛发作，因为此时血供跟不上心代谢的需要。

The myocardium also has dedicated blood vessels called coronary vessels, which lay on the outside of the heart and then penetrate into the myocardium to bring blood to that layer because it needs a lot of energy to pump blood.

心也有专门的血管，叫冠状动脉血管；位于心脏外侧，然后穿入心输血，因为心泵血需要消耗许多能量。

Because of this difference, the left ventricle needs to be stronger; and so the muscular layer of the left ventricular wall or its myocardium is three times thicker than the right ventricle's myocardium.

由于这种差异，左心室需要更强壮；因此左心室壁的肉，即心，比右心室的心厚三倍。

The muscular walls of the heart consist of three major " layers" . The bulk of the walls is made up of a layer of cardiac muscle and is called the myocardium.

心外层是心外膜，内层是心内膜。

Whatever the case, the heart needs blood, and if we look at the heart wall, there’s three layers—the outermost layer, the epicardium, then the myocardium in the middle, and the endocardium inside the heart.

无论什么情况下，心都需要供血，我们学习心壁时知道，心壁有3层：最外层的心外膜、中层的心，以及心脏内的心内膜。