Embolism在线视频

Last class we have talked about

Changes in blood volume

and changes in blood quality

In this class

we will continue to talk about

the adverse effects of the changes in blood quality on the body namely embolism

Embolism refers to the phenomenon of foreign bodies running with blood

and blocking blood vessels

Foreign bodies blocking blood vessels are called Embolus

Generally speaking

There are five ways of embolus operation

The first way is the embolus of the venous system

It is well known that

the venous system returns to the right heart through the vena cava

Therefore when the embolus of the venous system and right heart

flows into the right heart and into the pulmonary artery

it often causes pulmonary embolism

The second way is the embolus of the arterial system

when the embolus of the arterial system or the embolus of the left heart falls off

it will cause embolism of systemic arterial

and some small arteries

The third way is the embolus of portal vein system

The embolus of portal vein system is often embolized to the liver

eventually flows back through the liver

Because the blood recovered from the portal system

Fourth crossed embolism

For example some congenital heart diseases

When the atrial septum or ventricular septal defect

it may cause cross embolism

The fifth point is retrograde embolism

It's rare

It usually occurs when coughing or abdominal pressure and chest pressure increase

Transient blood reflux leads to retrograde occlusion of the embolus

This is the diagram of the running way of the embolus and embolism

As you can see from this diagram

The embolus of the venous system flows back to the right atrium through the vena cava

and passes through the right ventricle causing the embolism of pulmonary artery

While embolus in the left ventricle or artery often causes embolism in the arterial system

There are several types of embolism

thromboembolism fat embolism gas embolism

amniotic fluid embolism and other embolism

Other embolism refers to embolism caused by tumor parasite etc.

First let's talk about thromboembolism

It is the main cause of embolism

About 95% of the embolus come from the deep veins of the lower extremities

Generally speaking after the small embolus falls off

it reaches the right heart through the vena cava and then enters the pulmonary artery

which will not cause serious consequences

However when the course of disease is prolonged

it is easy to cause chronic pulmonary congestion

which may lead to hemorrhagic pulmonary infarction

When many emboli appear and when it is embolized to the trunk

it will lead to respiratory failure right heart failure or sudden death

In this diagram of blood flow changes during pulmonary embolism

we can see that normal lung tissue is supplied by double blood

In addition to pulmonary artery there are also bronchial artery

When pulmonary artery embolism occurs

pulmonary tissue can obtain blood supply through bronchial artery

which is the unique blood supply structure of pulmonary tissue

This picture shows pulmonary embolism

In the middle of the picture we can see the area indicated by the yellow arrow

We can see that there is a silkworm like thrombus in the opened pulmonary artery

which is the pulmonary congestion

caused by the thromboembolism after it reaches the pulmonary artery

There are two main mechanisms of sudden death caused by pulmonary embolism

First a sharp increase in intra-arterial resistance

leads to an increase in the afterload of the right heart

which in turn leads to acute right heart failure

Second embolization can stimulate the vagus nerve

Through the action of nerve reflex on coronary artery bronchial artery or bronchus

it can cause asphyxia or acute right heart failure

These are two common mechanisms of sudden death caused by embolism

In the embolism of systemic circulation

Most emboli come from left heart

It is usually based on thrombosis in the heart valve area of the patient

the thrombus falls off and causes arterial embolism of systemic circulation

which is the most common reason

The influence of thromboembolism on the body

mainly depends on the location of the embolism

the collateral circulation of the embolic organ

and the tolerance of the tissue to ischemia

These three aspects directly determine

the consequences of thromboembolism on the body

Next I'd like to introduce fat embolism

Embolism in the blood vessels causes corresponding lesions

The main and most common inducement is the fracture of the long bone shaft

Because there is yellow bone marrow in the long bone shaft

when fracture occurs

these fatty components

can enter the blood circulation system to cause pulmonary embolism

Generally speaking

the fat drop embolus with a diameter of more than 20 microns

may cause pulmonary capillary embolism

while the embolus with a diameter of less than 20 microns

can enter the systemic circulation through the pulmonary circulation

and then flow into the finer vascular network with the systemic circulation

to cause embolism such as cerebral embolism

A small amount of lipid drips into the blood can be removed by macrophages

without adverse consequences

but when most of the lipid drips into the blood

it will cause most of the pulmonary circulation area to be blocked

resulting in asphyxia and right heart failure leading to death

In this picture We can see that

there are fatty components in the blood vessels of the lung tissue

and in the fatty components

the components of the lymphocytes can be seen

so this is probably the pulmonary artery fat embolism caused by the long bone shaft fracture

This is a high-power picture of the previous one

The empty and bright areas are the areas occupied by fat droplets

which are mixed with many cell components of the lymphocytes

Gas embolism is rare

It mainly occurs in caisson disease also known as diver's disease

It is caused by rapid transition from high pressure environment to low pressure environment

Normally

from high pressure environment to low pressure environment

the original dissolved gas in the blood quickly dissociated into bubbles

and oxygen and carbon dioxide could be dissolved again

Nitrogen formed microbubbles or large bubbles

blocking blood flow or directly damaging the cells

blocking the coronary artery and leading to death

There are other causes of air embolism

such as a negative pressure chest during lung surgery

or a strong contraction of the uterus during childbirth

which can cause external air to enter the blood circulation

and cause embolism

If the amount of embolic air is small enough

to dissolve in the blood

there will be no serious consequences

but when a large amount of gas (such as more than 100ml) enters the blood circulation

it will cause acute heart failure and sudden death

we can see that

About the consequences of air embolism

a few or small bubbles

will not cause serious systemic adverse reactions

Next we will talk about decompression sickness also known as caisson disease

is released into the blood system during the rapid reversal of pressure difference

which is a process in which nitrogen dissolved in the blood

forming such microbubbles or big bubbles

to block the blood vessels

which is the main cause of caisson disease

Finally we will introduce some rare types of embolism

amniotic fluid embolism parasite embolism and tumor embolism

Although amniotic fluid embolism is rare

it is a serious complication in the process of delivery

The main reason is that

when the amniotic membrane ruptured the fetus blocked the birth canal

and the strong contraction of the uterus led to the increase of intrauterine pressure

At this moment amniotic fluid or fetal hair and other substances

were squeezed into the venous sinus of the ruptured uterine wall

causing pulmonary embolism

Its pathological changes are mainly that

fetal hair fetal fat meconium and mucus can be seen in the embolized arterioles of the lung

which often lead to serious consequences

such as pulmonary embolism anaphylactic shock or DIC

Next let's look at some pictures

In this picture

pink and wavy keratinized epithelium can be seen in the capillaries of the lung

which is probably

caused by the exfoliated epithelial components of the fetal keratinization

which also belongs to the category of amniotic fluid embolism

This picture shows a relatively rare type of embolism

It is a kind of tumor embolism formed by tumor cells embolizing into blood vessels

We can see the normal brain tissue on the right side

in the blood vessels on the surface of the left brain tissue

the tumor embolic substance can be seen

These are the common types of embolism

Thanks for your listening