Embolies

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I- Definition :

embolism is called the migration of a foreign body or emboli in the circulatory current and judgment in a vessel whose caliber is insufficient to deliver his way.

II- Journey of the embolus :

1- direct embolism :

normal path, in the direction of blood flow Example & rsquo; pulmonary embolism : the path followed is that of the venous blood :

Vein fémorale- "vena cava -" heart right- "pulmonary artery.

2- paradoxical journey :

Exceptionally, may exist paradoxical embolism, avoiding pulmonary filter in case of congenital heart diseases which are accompanied by a significant left to right shunt : ventricular septal defect (CIV) atrial septal defect (CIA) or arteriovenous fistula :

Femoral vein → vena cava → right heart → left heart → aorta and systemic circulation.

3- retrograde journey :

More rarely, embolism is retrograde kind due to the & rsquo; momentary reversal of blood to the & rsquo current; occasion dune right ventricular failure s & rsquo; joins chest hyperpressure to temporarily reverse the current in the vena cava or & rsquo; coughing or defecation.

Femoral vein → vena cava → renal vein → renal infarction.

III- etiological forms :

1- The solid emboli :

A- Blood emboli :

They represent 95 % du full name des emboles. When & rsquo; n & rsquo it, not otherwise specified, embolus the term is used to refer thromboembolism.

These emboli released from a thrombus or most often fragmented, which migrates into the bloodstream.

1- Thrombosis of the veins the great movement of the lower limbs, pelvic plexus, IVC. They give pulmonary embolism.

2- Cardiac thrombosis :

The left cardiac thrombosis interest usually the left ventricle (Mural thrombosis myocardial infarction), l & rsquo; left atrium (mitral stenosis) or valves (vegetation endocarditis).

They give emboli into the systemic circulation, with renal localization, splenic, legs, hepatic, brain.

3- arterial thrombosis :

The fragmentation of the clot will close off the downstream bed.

4- Evolution :

L’embole, when stopped in a small arms ship, will cause thrombosis of the vessel and will have the same pattern as the thrombus.

It can therefore undergo a therapeutic or spontaneous fibrinolysis, causing which resolved without sequelae. In other cases, thrombus organization will undergo a conjunctive.

A histological examination, it will not be possible to differentiate an old organized thrombus an embolus organized. Only the sequence of clinical events will distinguish.

B- tissue emboli :

1- atheromatous embolus. The s & rsquo; agit d & rsquo; a embole artériel Q obstruer artères les plus de petit caliber du lit d'aval. It can be either clot fragments fibrinocruoriques applied against the roof of the fibrous plaque, or atheromatous recognizable slurry crystals of cholesterin surrounded by giant cells, Finally, either calcified plaque fragments.

2- fat embolus :

The most common are related to migration of adipose tissue, subcutaneous tissue or hematopoietic marrow in elderly people especially after trauma with open fracture.

These lesions are found on microscopic examination of the lungs where the light of the small vessels is occupied by the adipose tissue sometimes mixed with small bone spicules and hematopoietic cells.

Bone marrow emboli are common in pulmonary vessels after cardiac massage and usually remain asymptomatic.

3- infectious emboli :

Necrotic or fibrin fragments containing microbial colonies (e.g. fragment vegetation d & rsquo; bacterial endocarditis) can migrate from & rsquo; an infected home.

4- neoplastic emboli :

Embolisms cancer cells determine the & rsquo; emergence of metastases.

2- Emboles liquidiens : Amniotic fluid embolism

During d & rsquo; a difficult delivery, there may be amniotic fluid passage in the maternal circulation, as a result of & rsquo; tearing of placental membranes or & rsquo; uterine rupture and / or cervical veins.

3- gaseous emboli :

It s & rsquo; is gas bubbles obliterating the vascular lumen. They can s & rsquo; observe two circumstances.

→ embolism d & rsquo; exogenous air :

It s & rsquo; is the & rsquo; & rsquo accidental introduction; air in the bloodstream : trauma with vascular wound, intra venous injection. Only an amount of & rsquo; large air (50 at 100 cc) has clinical translation.

→ endogenous gas embolism :

The bends or decompression syndrome is observed in subjects exposed to sudden changes in atmospheric pressure. It s & rsquo; these are scuba divers or & rsquo; workers working underwater constructions.

In case of sudden decompression, blood gases pass the & rsquo; dissolved in & rsquo; gaseous state and form multiple small bubbles responsible for multiple emboli obstructing the light hair of fine gauge : lungs, muscles, brain, the.

IV- Consequences :

1- local consequences :

  • circulatory related to the & rsquo disturbances, vascular obstruction (Acute ischemia can cause the formation of & rsquo; infarction).
  • Consequences related to the nature of the embolus : septic emboli causes metastatic abscess or may be responsible for & rsquo; aneurysm microbial lysis of the vascular wall.
  • Neoplastic emboli may be in & rsquo; origin & rsquo; tumor metastasis.

2- General consequences :

They are mostly the fact pulmonary embolism, the most serious and the most frequent: The sudden death from massive embolism, but also rain of small emboli.

However, it n & rsquo; is no compulsory parallelism between the degree of & rsquo; vascular obstruction and functional impairment.

Dr M's course. Corner – Faculty of Constantine