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了解心脏病和心肌梗塞

An Osmosis Video: Heart Attack Explained

《渗透医学》
According to the world health organization,
根据世界卫生组织的报道
cardiovascular disease is the leading cause of death worldwide
在全球范围 心血管疾病是头号杀手
as well as in the US
包括美国在内
of those a large proportion are caused by heart attacks,
这其中很大一部分是死于心脏病
also known as acute myocardial infarctions, or just myocardial infarctions,
也就是急性心肌梗死 或心肌梗死
sometimes just calledMI.
有时简称“心梗”
The word infarction means that some area of tissue has died
梗死的意思是因为缺乏血液流动
due to a lack of blood flow and therefore a lack of oxygen
从而引发缺氧 使某些组织区域死亡
“ Myo ” refers to the muscle
肌是指肌肉
and “ cardial ” refers to the heart tissue
心是指心脏组织
So the heart attack or MI
所以心脏病或心梗
you have death of heart muscle cells
会导致心肌细胞死亡
because of a lack in blood flow,
因为血液缺乏流动
a process called necrosis.
这一过程称为坏死
Now the heart’s main job is to pump blood to your body’s tissues right?
心脏的主要工作是将血液泵入全身组织 对吧
well,the heart also needs blood,
但心脏自己也需要血液
and so it also pumps blood to itself
因此心脏会通过冠脉循环
using the coronary circulation.
将血液输送给自己
The coronary circulation is this system of small arteries and veins
冠脉循环是一个由小动脉和静脉组成的系统
and help keep the heart cells supplied with fresh oxygen
它可以给心脏细胞提供新鲜氧气
heart attacks happen when these small arteries become blocked
当这些小动脉阻塞时 心脏病就会发作
and it stopped supplying blood to the heart tissue
动脉停止向心脏供血
if this happens for long enough heart tissue dies
如果持续时间足够长 心脏就会死亡
almost all heart attacks are ultimately a result of
几乎所有的心脏病都是因为
endothelial cell dysfunction
血管内皮细胞功能障碍
which relates to anything that irritates or
各种刺激物或引起光滑的动脉内膜发炎的物质
inflames the slippery inner lining of the artery the Tunica intima
都会让血管内皮细胞产生功能障碍
One classic irritant are the toxins found in tobacco
烟草中的毒素是一种典型的刺激物
which float around in the blood and damage these cells
它漂浮在血液中并损伤血管内皮细胞
That damage then becomes a site for atherosclerosis,
这种损伤会导致动脉粥样硬化
a type of coronary artery disease where deposits of fat
这是一种冠状动脉疾病
cholesterol proteins calcium and white blood cells build up
它会让脂肪 胆固醇 蛋白质 钙和白血球堆积
start to block blood flow to the heart tissue this
并开始阻止血液流向心脏
this mound of stuff has two parts to it
堆积的物质由两部分构成
the soft cheesy textured interior
柔软的脂质内部
and the hard outer shell which is called the fibrous cap
还有坚硬的外壳 也叫做纤维帽
Collectively this whole thing’s ominously called plaque.
这些堆积的物质统称为动脉粥样斑块
Usually, though, it takes years for plaque to build up,
但通常情况下 斑块的形成需要数年
and this slow blockage only partially blocks the coronary arteries,
这类缓慢形成的阻塞物只会部分阻塞冠状动脉
and so even though less blood makes it to heart tissue,
因此进入心脏的血液虽然减少了
there’s still blood.
但供血还是有的
Heart attacks happen when there’s a sudden complete blockage or
当冠状动脉突然完全堵塞或闭塞时
occlusion of a coronary artery
心脏病就会发作
so let’s see how that can happen.
所以让我们来看看心脏病是如何发作的
Since these plaques sit right in the lumen of the blood vessel,
因为这些斑块正好位于血管腔内
they’re constantly being stressed by mechanical forces from blood flow,
血液流动会不断地给它们施加机械力负荷
and interestingly it’s often the smaller plaques with softer caps
通常小斑块的纤维帽会更软
rather than the larger ones with harder caps
大斑块的纤维帽会更硬
that are especially prone to break or get ripped off.
但有趣的是前者比后者更容易破裂或脱落
Once that happens the inner cheesy filling
一旦破裂或脱落 里面的脂质堆积物
which remember is this mix of fat, cholesterol, proteins, calcium,
即由脂肪 胆固醇 蛋白质 钙
and white blood cells is thrombogenic
和白细胞组成的混合物就会形成血栓
and this means that it tends to form clots very quickly.
这意味着血块形成的速度会非常迅速
So platelets, or blood-clotting components in the blood,
血液中的血小板或凝血成分
flow by and get excited;
会被激活 然后聚集起来
and they adhere to the exposed cheesy material.
并附着于裸露在外的脂质层上
In addition to piling up,
除了聚集堆积
the platelets also release chemicals that enhance the clotting process.
血小板还会释放出促进凝血过程的化学物质
Now this happens super fast,
这个过程会非常迅速
think about how quickly a small cut stops bleeding,
想想小伤口止血的速度有多快
that’s a very similar process
这两个过程很相似
it happens in a matter of minutes, right?
几分钟就能止血了 对吧
And now that coronary artery is fully occluded.
现在冠状动脉就被完全堵塞了
So now let’s change views a bit,
让我们稍微转换下视角
If we take a slice of the heart like this,
如果我们像这样切开心脏看
this side being posterior, or back,
上面是心脏的后面
and this being anterior, or the front,
下面是心脏的正面
with the left and right ventricles here
左右心室在这里
and then we have the three most commonly blocked arteries
这里是三条最常发生堵塞的动脉
the left anterior descending or LAD
冠状动脉左前降支 简称左前降
which supplies blood to the anterior wall and septum of the left ventricle
它可以向左心室前壁和隔膜供血
which accounts for 40-50 % of cases,
供血量占左心室供血量的40-50%
the right coronary artery, or the RCA
右冠状动脉 简称右冠脉
which covers the posterior wall, septum and papillary muscles of the left ventricle
可以给左心室的后壁 隔膜和乳头肌供血
accounts for about 30-40 % of cases,
供血量占左心室供血量的30-40%
and finally, the left circumflex artery, or LCX
最后是冠状动脉左回旋支 简称左回旋支
which supplies to the lateral wall of the left ventricle
它可以向左心室侧壁供血
about 15-20% of cases.
供血量约占左心室供血量的15-20%
Notice that the majority of these areas supply the left ventricle
注意 大部分这些动脉都在给左心室供血
most heart attacks therefore involve the left ventricle,
因此 大多数心脏病都与左心室有关
where the right ventricle and both atria—the upper chamber—
右心室和心房 即上腔室
aren’t as often affected.
通常不会受到影响
Each of these areas is called the artery’s zone of perfusion.
这里的各个区域都被称为动脉灌注区
and if we take a closer look at one of these zones,
如果我们放大这块区域来看
we’ll see that basically you’ve got the endocardium,
可以看到这里主要有心内膜
which is the smooth membrane on the inside of the heart,
即心脏内部的平滑膜
and then the myocardium, all the heart muscle
然后是心肌 即心脏的肌肉
and then, the epicardium, the outer surface of the heart which
再然后是心外膜 即心脏外面的一层膜
which is where the coronary arteries live.
这里也是冠状动脉所在的位置
Let’s say the LAD gets blocked,
假设左前降发生堵塞
the area of perfusion is now at serious risk,
灌注区就会处在极其危险的境地
and within about a minute,
大约在一分钟内
the muscle cells in this zone don’t see enough oxygen and become ischemic,
这个区域的心肌细胞就会缺氧并出现缺血
and the muscle layer’s ability to contract is severely reduced.
肌肉层的收缩能力也会严重减弱
This initial stage is extremely sensitive,
这个过程初期时会非常敏感
since the ischemic damage to cells in the perfusion zone
因为灌注区因缺血而损伤的细胞还是可逆的
After about 20-40 minutes, though,
但约20至40分钟后
damage starts to become irreversible and the cells start to die,
损伤开始变成不可逆转的 细胞也开始死亡
and this zone changes to a zone of necrosis, or dead tissue.
这个区域变成了坏死区 或坏死组织
Once lost, these cells will never return or regrow
心肌细胞一旦死亡便不能恢复或再生
that’s why quickly identifying and treating an MI is super important
因此迅速诊断并快速治疗心梗至关重要
The first area affected is the inner third of the myocardium,
首先受到影响的是心室壁内侧1/3的区域
since it’s farthest from the coronary artery
因为它离冠状动脉最远
and the last area to receive blood,
是最后一个得到供血的区域
and it’s subject to higher pressures from inside the heart.
并且它受到的心脏内部的压强更大
If the blockage suddenly lyses or breaks down and blood flow returns,
如果阻塞物突然溶解或分解 血流也恢复
sometimes patients ’ damage will be limited to the inner third,
有时病人的损伤只会在心室壁内侧1/3处
and this would be called a subendocardial infarct.
这种病症叫做心内膜下心肌梗死
An ECG, or electrocardiogram,
心内膜下心肌梗死的心电图
done at this point typically shows an ST-segment depression,
通常显示为ST段压低
or in other words, it doesn’t show ST segment elevation,
换句话说就是不显示ST段抬高
so sometimes we call this an NSTEMI
因此我们有时会称之为NSTEMI
which stands for non-ST elevation myocardial infarction.
全称非st段抬高性心肌梗死
Other causes of this sort of subendocardial infarcts
心内膜下心肌梗死的其他致病因素还有
would be severe atherosclerosis and hypotension
严重的动脉粥样硬化和低血压
anything that ultimately leads to poor perfusion of the heart tissue.
以及各种导致心脏灌注区损伤的因素
After about 3 to 6 hours, though,
但大约3到6小时后
the zone of necrosis extends through the entire wall thickness,
坏死区将会累及整个心室壁
called a transmural infarct,
我们称之为透壁性梗死
which this time shows up as ST-segment elevation on ECG
此时心电图显示为ST段抬高
which is why they’re sometimes called STEMIS,
所以称之为STEMIS
or ST elevation myocardial infarctions.
全称ST段抬高性心肌梗死
So the difference between NSTEMIs and STEMIs is that NSTEMIs
因此NSTEMIS和STEMIS的区别是
don’t have ST-segment elevation,
非ST段抬高性心梗没有ST段抬高
and these are caused by partial infarct of the wall,
并且是由心室壁部分梗塞引起的
whereas STEMIs have ST-segment elevation
ST段抬高性心梗有ST段抬高
and involve the whole wall thickness.
并且心梗累及到了整个心室壁
Patients that have an MI will most commonly have
患有心梗的病人通常会有
severe and crushing chest pain or pressure,
严重的 剧烈的胸痛或胸闷
that might radiate up to the left arm or jaw,
还可能会辐射到左臂或下颌
they might have diaphoresis or sweating,
他们可能会有发汗 盗汗
nausea, fatigue, and dyspnea.
恶心 疲劳 呼吸困难的症状
All of these are either a direct result of an end-organ
以上都是终末器官受损的直接反应
like the heart or the brain not getting enough perfusion
比如心脏或大脑未得到足够的血液灌注
so think chest pain and dizziness.
就会出现胸痛和头晕
Or from the sympathetic response from the body
或者为了让心脏更好运转 维持血压
to help the heart work harder and preserve blood pressure
身体就会出现皮肤交感反应
so think sweating and clammy skin.
于是就出现流汗和皮肤湿黏的症状
Many people also have referred pain
许多人还会出现牵涉痛
where the nerves in the heart are irritated,
因为心脏的神经受到了刺激
but that pain can be felt in the jaw,
但这种疼痛会出现在下颌
shoulder, arm, or back instead.
肩膀 手臂或背部
In addition to an ECG, labs can be
除了心电图 实验室检查对
very useful in diagnosing an MI.
心梗的诊断也是很有用的
When there’s been irreversible damage to heart cells,
当心肌细胞受到了不可逆的损伤
their membranes become damaged
细胞膜也会受损
and the proteins and enzymes inside escape,
细胞内的蛋白质和酶就会跑出来
and can enter the bloodstream.
进入到血液中
Three key ones are troponin I, Troponin T, and CK-MB
三个关键指标 肌钙蛋白I 肌钙蛋白T 和CK-MB
which is a combination of creatine kinase enzymes M and B
即肌酸激酶M和肌酸激酶B的组合物
Both troponin I and T levels can be elevated in the blood
在发生心梗2到4小时内
within 2-4 hours after infarction,
肌钙蛋白I和T在血液中含量会升高
and usually peak around 48 hours,
通常约48小时后到达峰值
but stay elevated for 7-10 days.
但在7到10天内降至正常
CK-MB starts to rise 2-4 hours after infarction,
心梗后2到4小时 CK-MB开始升高
peaks around 24 hours, and returns to normal after 48 hours.
约24小时后达到峰值 48小时后恢复正常
Since CK-MB returns to normal more quickly,
因为CK-MB恢复到正常的速度更快
it can be useful to diagnose reinfarction,
所以它对再梗死的诊断是很有用的
a second infarction that happens after 48 hours
心肌二次梗死会在48小时后出现
but before troponin levels go back to normal.
但此时肌钙蛋白还没恢复正常
A second heart attack happens following 10% of MIs.
10%的心梗患者会出现心肌二次梗死
A major complication with MIs are arrhythmias,
心梗的主要并发症是心律不齐
or abnormal heart rhythms,
或称心律异常
with the highest risk being immediately following an MI,
心律失常的危险指数仅次于心梗
since the damage or injury can disrupt how the cells conduct electrical signals.
因为它会损伤或破坏细胞的电信号传导
Kind of along the same lines,
与心梗差不多
depending on how much contractile or muscle tissue is affected,
根据心脏收缩功能和心肌受到的损伤程度
patients’hearts might not be able to pump enough blood to the body,
患者的心脏可能无法向全身输送足够的血液
resulting in cardiogenic shock.
从而导致心源性休克
In the days following an infarction,
心梗后的几天内
the tissue around the infarcted area becomes inflamed
梗死区域的组织开始发炎
and is invaded by neutrophils,
中性粒细胞侵润梗死区域
which can lead to pericarditis,
就会导致心包炎
inflammation of the pericardium.
就是心包膜的炎症
In the next couple weeks, macrophages invade the tissue,
接下来的几周里 巨噬细胞侵入组织
and the healing process begins with the formation of granulation tissue,
肉芽组织形成 这标志着愈合修复进程开始
which is new connective tissue that’s yellow and soft.
新生的结缔组织呈现黄色 质地柔软
At this phase, the tissue’s most at risk of myocardial rupture.
在这个阶段 心脏最容易发生心肌破裂
After 2 weeks to several months,
2周到几个月内
the cardiac tissue scarring process finishes,
心脏组织形成瘢痕的过程结束
and the resulting tissue becomes grayish-white in color.
形成的瘢痕组织呈现灰白色
Since the scar tissue doesn’t help pump blood,
由于瘢痕组织无泵血功能
over time the remaining heart muscle can grow or change shape
久而久之 剩下的心肌会生长或发生变形
to try and compensate for these lost cells
它们会更卖力地进行泵血
and pump harder,
试图代替死去的细胞
but they ultimately continue to fail, which can lead to heart failure.
但最终仍会失败 并且还会导致心脏衰竭
Now a potentially life-saving treatment that
目前有种可能挽救生命的疗法
can be performed immediately following an MI,
它可以在心梗发作时立即实施
is fibrinolytic therapy,
这种疗法叫纤容治疗
which uses medications to break down fibrin in blood clots.
这种方法用药物来分解血凝块中的纤维蛋白
An angioplasty might also be done,
血管成形术也可以用来治疗心梗
which is a minimally invasive endovascular procedure
这是一种微创侵入式血管手术
where a deflated balloon inserted into the blockage
这种方法将一个未充气的球囊插入血栓
then inflated to help open the artery
通过充气帮助血管疏通
And finally a percutaneous coronary intervention might also be performed,
最后也可以采用经皮冠状动脉介入治疗
where a tiny catheter is used to place a stent in the coronary artery
用极小导管在冠状动脉中放置支架
to physically open up a blood vessel.
运用物理方法疏通血管
Each of these focuses on
每种疗法的侧重点都是
re-establishing blood flow to the the dying heart heart cells
让血液重新流向已经死亡的心脏细胞
since time is tissue.
因为时间就是生命
If early enough following blockage,
如果血管能够尽快疏通
some of these cells that haven’t entered into the irreversible stage
一些还未进入到不可逆阶段的心肌细胞
can be salvaged and saved,
还可以被抢救回
while the others will be destroyed and removed.
没法拯救回来的细胞将会被摧毁和清理
This can improve both short and long-term function
这可以改善心脏短期和长期的机能
as well as prevent further damage
并避免造成进一步损伤
and reduce the overall zone of necrosis.
减少整体坏死区域的面积
Now an important complication of re-establishing perfusion,
但目前重建灌注或再灌注治疗的
or reperfusion therapy, is reperfusion injury,
一个主要并发症是再灌注损伤
where tissue is damaged by returning blood flow.
血液回流造成心脏组织损伤
And, this is thought to happen because of a couple mechanisms.
目前认为这是由多种因素导致的
First, blood flowing back to cells brings this influx of calcium
首先 血流回流会带着钙离子一起回流
and since calcium leads to muscle contraction,
因为钙离子会使肌肉收缩
the irreversibly damaged cells contract,
受到不可逆损伤的细胞也会收缩
and since they’ve been irreversibly damaged,
又因为这些细胞的损伤是不可逆的
they get stuck like that and can’t relax.
它们就会收缩成这样 没法再反弹回来
This shows up on histology as this characteristic contraction band necrosis.
在组织学上表现为典型的收缩带坏死
Also though, blood brings along oxygen, right?
即便如此 血液还是携带了氧气 对吧
Yeah it does.
是的
But that oxygen, paradoxically,
但矛盾的是
can actually lead to more cellular damage.
氧气实际上会使细胞损伤加重
The conditions in an ischemic heart
心脏在缺血状态下
seem to cause an increased conversion of the returning oxygen
似乎会使更多的氧气
to reactive oxygen species,
转化成活性氧
which go on to damage more heart cells.
进而会破坏更多的心脏细胞
In addition to reestablishing blood flow though,
除了恢复血流
there are a number of medications that might be given in the acute setting
在紧急情况下还可以使用一些药物
including antiplatelet meds like aspirin,
如阿司匹林等抗血小板药物
anticoagulants like heparin,
肝素等抗凝剂
nitrates which relax the coronary arteries and help lower preload,
还有能让冠状动脉放松 降低预负荷的硝酸盐
beta blockers that slow down the heart rate and thereby cardiac demand,
减慢心率从而降低心脏需求的受体阻滞剂
pain medication to help relieve the discomfort,
也可以使用止痛药来缓解不适
and statins which help improve a patient’s lipid profile.
使用他汀类药物来改善患者血脂
now there are a ton of individual factors to consider when
在心肌梗死的紧急治疗中
when it comes to acute management of a myocardial infarction,
需要考虑到诸多的个体因素
and of course many long term issues to consider as well
当然还要考虑一些长期的问题
the most important of which is to address the underlying risk factors
其中最重要的是解决潜在的风险因素
like an improved diet and quitting smoking.
如改善饮食和戒烟
All right as a quick recap.
快速回顾一下
Heart attack, also known as myocardial infarction, or MI,
心脏病 也称心肌梗死或心梗
is the death of heart muscle cells due to the lack of blood flow,
是种由于血液缺乏流动导致心肌细胞死亡的疾病
most commonly caused by atherosclerosis of the coronary arteries.
通常是由冠状动脉粥样硬化引起的
The most common symptoms of MI include
心梗最常见的症状包括
crushing chest pain or pressure that
挤压性胸痛或胸闷
might radiate up to the left arm or jaw ,
疼痛还可能辐射到左臂或下颌
sweating, nausea, and dyspnea.
还会出现出汗 恶心 呼吸困难的症状
Treatment of MI includes re-establishing blood flow using medications, angioplasty,
心梗的治疗有通过药物 血管形成术
or percutaneous coronary intervention.
经皮冠状动脉介入重建血流等疗法
Underlying risk factors should be addressed for long term management.
其潜在的危险因素需要得到长期的控制
thanks for watching
感谢收看
if you’re interested in a deeper dive on this topic
如果你有兴趣深入地探讨一下这个话题
take a look at as Moses org where
可以登录Moses.org
we have flashcards, questions and other awesome tools to help you learn medicine
网站上有问题 抽认卡和一些很棒的工具来帮助你学习医学
otherwise you can always support us by donating on patreon
另外 您可以通过Patroen给我们捐款
subscribing to our channel or following us on social media
订阅或在社交媒体上关注我们的方式来支持我们

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译制信息
视频概述

关于心肌梗死的机理,治疗及控制危险因素

听录译者

收集自网络

翻译译者

Claudia

审核员

审核员1024

视频来源

https://www.youtube.com/watch?v=2kLlhlsesRQ

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