What are Embolisms?

Embolism refers to the phenomenon that abnormal substances insoluble in blood appear in circulating blood and flow with the blood, thereby blocking the lumen of blood vessels. Embolism is also a life reaction. If there is a fracture or extensive soft tissue injury, fat or bone marrow embolism is found in the lung at necropsy, it can be proved to be an antenatal injury; when the jugular vein is damaged and open rupture, a large amount of air enters the right heart through its opening, forming an air plug This is sufficient to prove that the jugular vein injury is a prenatal injury. ^[1]

[shun sè]

Embolism refers to the phenomenon that abnormal substances insoluble in blood appear in circulating blood and flow with the blood, thereby blocking the lumen of blood vessels. Embolism is also a life reaction. If there is a fracture or extensive soft tissue injury, fat or bone marrow embolism is found in the lung at necropsy, it can be proved to be an antenatal injury; when the jugular vein is damaged and open rupture, a large amount of air enters the right heart through its opening, forming an air plug This is sufficient to prove that the jugular vein injury is a prenatal injury. ^[1]

[Pronunciation] shun sè

English

embolism (n.)

embolize (v.)

The phenomenon that abnormal substances insoluble in the blood appear in the circulating blood and block the vascular cavity with the blood flow to a distance is called embolism. A substance that blocks blood vessels is called

(A) thromboembolism

Embolism caused by thrombotic detachment is called thromboembolism and is the most common form of embolism. Due to the different sources of thrombi, the size of the emboli and the location of the embolism, the impact on the body is also different.

Pulmonary embolism

More than 90% of the emboli in pulmonary arterial thromboembolism come from the deep veins of the lower limbs, especially the iliac vein, femoral vein, and iliac vein, followed by the pelvic vein, or the ovary, periprostatic vein, and uterine vein, and occasionally from the right heart wall thrombus. The consequences of pulmonary embolism depend on the size and number of emboli and the state of pulmonary function. There are generally three cases:

If the emboli are small and the pulmonary function is good, there will not be serious consequences, because the lung has dual blood circulation. At this time, the tissues in the pulmonary artery distribution area can get blood supply from the bronchial artery. These emboli can be dissolved and absorbed or mechanized. Become fibrous strands;

Although the emboli is small, before the embolism, the lungs have been severely congested, causing the internal pressure of the microcirculation to rise, blocking the blood supply to the bronchial artery, and the collateral circulation not fully functioning, which can cause hemorrhagic infarction of the lung tissue;

Embolism from lower extremity veins or right ventricular mural thrombus, because of its large size, is often embolized to the main or large branch of the pulmonary artery, or many small thrombus, which can block most pulmonary artery branches, which can cause sudden death. The patient manifested as: sudden dyspnea, chest pain, cough, cyanosis, shock, etc., called pulmonary embolism or stroke. Such cases often occur in patients who do not get out of bed in a timely manner after major surgery or who are chronically ill, and who suddenly wake up after venous thrombosis of the lower extremity.

The cause of sudden death of pulmonary embolism has not been fully elucidated. The following reasons are generally considered:

Pulmonary artery main or large branch embolism, pulmonary artery resistance increases sharply, causing acute right heart failure.

Studies have shown that the stimulation of the intima of the arteries by a large number of small emboli causes excitement of the vagus nerve and the release of a large amount of serotonin and thromboxane A2 from the platelets in the emboli, which cause spasm of the pulmonary artery, coronary artery, bronchial artery and bronchus through neural reflex, resulting in Acute pulmonary hypertension, right heart failure, and asphyxia are also related to myocardial ischemia due to insufficient coronary perfusion.

2. Systemic arterial embolism

Most emboli come from mural thrombus in the left heart and arterial system (such as heart valve vegetation in subacute bacterial endocarditis, left atrium wall thrombus in mitral stenosis, and mural thrombosis in myocardial infarction) Thrombosis occurs on the surface of atherosclerotic ulcer or aortic aneurysm; very few emboli from the vena cava can enter the left heart through atrial and ventricular septal defects, and cross embolism occurs. The main parts of arterial embolism are the lower limbs and the brain, which can also affect the intestines, kidneys and spleen. The consequences of embolization depend on the location of the embolism and the local collateral circulation and the tolerance of the tissue to ischemia. When an embolized artery lacks effective collateral circulation, it can cause infarction of local tissue.

(B) Fat embolism

Refers to fat embolism in the circulating blood flow that obstructs small blood vessels. Embolism sources are commonly found in long bone fractures, adipose tissue contusions, and fatty liver crush injuries. Fat cells rupture and release lipid droplets, which enter the blood circulation through ruptured small veins.

Fat embolism is common in organs such as lung and brain. Lipid emboli follow the vein into the right heart to the lung. Lipid emboli with a diameter of more than 20 m cause embolism of branches, arteries or capillaries of the pulmonary artery; lipid emboli with a diameter of less than 20 m can pass through the pulmonary vein to the left through the alveolar capillary The branch of Xinda systemic circulation can cause embolism of multiple organs throughout the body. The most common is the embolization of cerebral blood vessels, which causes cerebral edema and spotted bleeding around the blood vessels. Lipid droplets can be found in the blood vessels under the microscope. Its clinical manifestations can be sudden onset of shortness of breath, dyspnea and tachycardia after injury.

(Three) gas embolism

A large amount of air quickly enters the blood circulation or the gas originally dissolved in the blood is rapidly released, forming air bubbles to block the cardiovascular system, which is called air embolism.

Air embolism is mostly caused by venous injury and the outside air enters the bloodstream from the venous defect. Such as head and neck surgery, chest wall and lung trauma injury to veins, the use of positive pressure intravenous infusion and artificial pneumothorax or pneumoperitoneum accidentally injured veins, air can be attracted by the negative pressure in the vein cavity when inhaled, and enter the vein from the injured mouth.

The consequences of air entering the bloodstream depend on the speed of entry and the amount of gas. A small amount of gas enters the blood and can be dissolved into the blood without gas embolism. If a large amount of gas (> 100ml) enters the vein quickly, after the blood flows to the right heart, the air and blood are stirred by the heart to form a large number of bubbles, which makes the blood become a compressible foam and fills the heart cavity, preventing the return of venous blood. And the output to the pulmonary artery, causing severe circulatory disorders. Patients may experience dyspnea, cyanosis, and sudden death. Some of the air bubbles entering the right heart can enter the pulmonary arteries, blocking small branches of the pulmonary arteries, causing gas embolism of the pulmonary arterioles. Small bubbles can also pass through small branches of the pulmonary artery and capillaries to the left heart, causing embolism of some organs in the systemic circulation.

Decompression sickness, also known as caisson disease and divers disease, is a type of gas embolism. Decompression refers to the rapid entry of the human body from a high-pressure environment to a normal-pressure or low-pressure environment, so that the gas originally dissolved in blood, interstitial fluid and adipose tissue, including oxygen, carbon dioxide and nitrogen, is rapidly released to form bubbles, but oxygen and carbon dioxide can be redissolved Body fluids are absorbed, and nitrogen dissolves slowly in body fluids, resulting in the formation of many micro-bubbles or fusion into large bubbles in blood and tissues, which in turn causes embolism.

(IV) Amniotic fluid embolism

Amniotic fluid embolism is a rare and severe comorbidity (1 in 50,000 people) during childbirth with a very high mortality rate. During delivery, when the amniotic membrane is ruptured or prematurely ruptured, the placenta is stripped early, and the fetal obstructs the birth canal, due to the strong contraction of the uterus and increased intrauterine pressure, the amniotic fluid can be pressed into the ruptured sinus wall of the uterus, and the blood circulation enters the branches of the pulmonary artery, Arterioles and capillaries cause amniotic fluid embolism. A small amount of amniotic fluid can pass through the pulmonary capillaries to the left heart through the pulmonary artery, causing embolism of small blood vessels of the systemic circulation organs. Microscopic observation of the amniotic fluid components such as keratinized squamous epithelium, fetal hair, sebum, meconium and mucus in the small arteries and capillaries of the lung. The disease is acute, and patients often experience sudden dyspnea, cyanosis, shock, and death.

Sudden death caused by amniotic fluid embolization In addition to mechanical obstruction of the pulmonary circulation, fetal metabolites in amniotic fluid enter the blood and cause anaphylactic shock and reflex vasospasm. At the same time, amniotic fluid has coagulation-activating enzyme-like effects that cause DIC, leading to death of patients.

(5) Other embolisms

Tumor cells can cause embolism during metastasis. Parasite eggs, bacteria or fungal masses and other foreign objects such as bullets can enter the blood circulation and cause embolism.