25 June, 2011

Prevention of thrombosis

What is Thrombosis

Thrombosis is a pathological phenomenon in which a vein or artery of the circulatory system is blocked by a thrombus, which is a kind of plug consists of coagulated blood and cells, thus preventing the blood keeps flowing glass from that point.

The circulatory system consists of a network of blood vessels that carry blood from the heart to different organs and tissues (arterioles and capillaries) and a network of vessels of return (venules and veins) that allows the return of blood to the lungs. There expel red blood cells that transport carbon monoxide and oxygen reloaded. From the lungs, returns to the heart through the pulmonary veins (body only veins that carry oxygenated arterial blood), in turn, propel the heart again via the arteries throughout the body.

The risks of not preventing thrombosis

in both an artery and a vein thrombosis can occur. The effects are quite different depending on the case of one or another type of blood vessel. Thrombosis in a blood vessel is very serious because it prevents oxygenated blood continues to flow from that point to the tissues that depend on that artery. The result is ischemia (tissue suffering from lack of blood flow causing anoxia, which means cell suffocation from lack of oxygen.) When the ischemia lasts longer than the tissue can withstand irreversible death occurs in cells of the tissue, which is called infarction. Depending on how vital it is the organ affected and the extent of ischemia, there will be more or less serious effects for the rest of the body.

In the case of a heart attack for example, the impact is very serious because of coronary artery (heart artery) occluded depends a great deal of blood flow to the heart muscle (myocardium) or nerve tissue that controls the rhythm of the heartbeat. If the thrombus does not resolve the heart ends up with in a few hours a stroke of great extent or a serious malignant arrhythmia that makes it impossible to maintain its pumping function and thus cause death.

thrombosis that occurs in other organs such as brain, eye, kidney, limbs, etc.. may not be as strict when it comes to cause death, but always involve the loss of the organ that depended on irrigation cut off, with the important functional losses resulting therefrom (hemiplegia, paralysis of the lateral half of the body, loss of speech, vision loss, dementia , etc.)..

In the case of veins, thrombosis is not usually endanger the life of the person unless it affects the veins that carry blood to the lungs (pulmonary embolism) because that reoxygenation leaves the possibility of venous blood. Thrombosis is the more serious the more extensive the amount of lung blood flow that remains.

With venous thrombosis (pulmonary embolism except already mentioned) that is produced is not a situation of ischemia as such, but the obstruction blood out of the organ to which the vein, which usually causes inflammation, pain and swelling of affected tissues (accumulation of stagnant water from the blood into tissues that are drained by that vein).

Is it the same one thrombosis embolism?

No, not the same. The circulatory system requires two basic conditions to serve its important function, is the condition of the permeability and another defense of the structural integrity and hemostasis. The first relates to the need for blood vessels are always free for the passage of the blood, and the second refers to the need to repair the walls of the vessel in case they suffer an injury.

The body with very complex systems, keeping a delicate balance, ensuring a perfect harmony of the defense provided that the integrity and permeability as essential. In the case of the hemostatic system have to mention two key, the system of platelet aggregation and the coagulation system.

The aggregation system

consists of the first blood cells (platelets) that, as tile, stick to where necessary in order to plug a break.

The coagulation system

is constituted by the second blood proteins that promote the formation of anchors and cables of the cluster of platelets and other cellular debris, thus forming what is called a thrombus or blood clot.

At times, there are pathological situations or by going injuring the vessel wall (eg atherosclerosis ) or function improperly encourage active or poorly controlled aggregation systems and / or coagulation failure occurs balance and subsequent formation of thrombi occluding just by the glass full.

Thrombosis occurs always some unusual circumstances favors the formation of a thrombus attached to the vessel wall. Stroke, however, is the blockage of a blood vessel by a clot that has formed in the circulation or that is a fragment of a blood clot that has traveled through the bloodstream to a stop at the point where it can no longer continue and that fell from an earlier point in the vessel wall where it formed. Thrombosis therefore occurs at the point where the vessel wall has suffered an injury and stroke distance occurs at a point other than where it generated the first thrombus.

What diseases cause thrombosis?

The list of processes that favor the production of thrombosis is quite large:

Arterial thrombosis


is worth noting at the head of all atherosclerosis, a vascular degeneration process favored by certain well-known risk factors for all ( hypertension , snuff , obesity , high cholesterol , excessive alcohol consumption , sedentary lifestyle, diabetes , etc.)..

In atherosclerosis is being produced the deposition of cholesterol and other fats in the wall of large vessels, which narrows the inside of them and ends up producing a rupture of the inner vessel layer (intima-called .) This leads to multiple platelet adhesion and the formation of a blood clot just completely occluding blood flow.

Heart disease

Other processes can produce arterial thrombosis are those cardiac diseases that favor cap or turbulent flow of blood as it passes through the chambers of the heart, as if the blood stops is also encouraged the formation of clots.

In this group of processes are some cardiac arrhythmias (atrial fibrillation, sick sinus syndrome, etc..), vascular malformations, diseases of the heart muscle (cardiomyopathy), the cardiac valve disease (valve) and atrial myxoma (tumor of the heart formed in the atrium).

Another heart disease that also causes increased risk of thrombosis is endocarditis (infection of the inner cell layer that lines the heart chambers.)

Coagulation disorders

The list of diseases that promote arterial thrombosis complete with some clotting disorders, certain diseases that increase the number of blood platelets (essential thrombocytosis) or viscosity (polycythemia, monoclonal gammopathies, leukemias ) and other diseases such as vasculitis, sickle cell, etc..

Venous thrombosis

processes that promote venous thrombosis are mostly different from those that increase the risk of arterial thrombosis.

The classically described as provocative factors for venous thrombosis (venous stasis, increased blood viscosity and hypercoagulability) are in full force and least one of them is always present in these diseases.

In this group we find the conditions in which adequate control is lost on power coagulant:

  • Primary hypercoagulability syndromes thrombofilias the primary (antitrombina III deficiency, protein C deficiency, Disease of Leyden, disfrinogenemias, etc..)

  • Hypercoagulability secondary states (cancer, antiphospholipid syndrome, pregnancy, nephrotic syndrome, consumption of some oral contraceptives);

  • Other causes such as prolonged immobilization in bed or hematological diseases (essential thrombocytosis, polycythemia vera, paroxysmal nocturnal hemoglobinuria, sickle cell disease, heparin-induced thrombocytopenia).

What ways are there to treat thrombosis?

Logically, when a thrombosis or arterial embolism far more useful and urgent treatment is one that will restore the blocked blood vessel patency before the ischemic infarction becomes final.

The time available to try this, in the heart attack for example, is only a few hours (6 to 12 hours.) One of the most used in this type of ailment is fibrinolytic therapy, which involves the administration of a or more drugs that dissolve the clot and restore the obstructed vessel permeability.

It is also possible to practice an emergency catheterization it to reach the key point of occlusion, fragmentation of the thrombus and dilate the vessel (angioplastia.) Within this technique it is also possible to accommodate within the coronary vessel permanent stent, which is a semi-rigid device that prevents the artery may close again. A complete technique is called interventional catheterization PTCA (percutaneous transluminal coronary angioplasty).

In the case of venous thrombosis, which in most of the time it happens in the veins of the legs, is not as pressing to recover the permeability the glass as if it is to relieve pain and other symptoms, and especially prevent detachment of the thrombus or fragments thereof, ascending cava veins, venous territory to reach the lungs and can cause a pulmonary embolism, as described above. To avoid this, so should be instituted early treatment with anticoagulant medication. Within this type of medication is the most widely used drug heparin as initial treatment, which can be later replaced by coumarin drugs such as acenocoumarol (Sintrom) for maintenance treatment, which must be satisfied for a longer time (usually 1 to 3 months.)

What ways are there to prevent thrombosis?

Without doubt, thrombotic disease prevention is no better than get reduce or eliminate the effect of those conditions that favor the deterioration of the circulatory vessels and the consequent formation of thrombosis. Thus, a measure of great benefit in preventing myocardial infarction, cerebral thrombosis or arterial thrombosis of the legs is trying to be free of the risk factors of atherosclerosis, for example.

Still, there is the possibility of reducing the systems based on aggregation and coagulation by antiplatelet drugs such as aspirin, clopidogrel, and so on. or anticoagulants such as heparin, coumarin derivatives (acenocoumarol, warfarin) or other more recent or imminent occurrence (Lepirudin, ximelagatran, Fondaparina, etc.).. The indication of one or the other is set based on the degree of risk of thrombosis, type of disease that favors the risk, the patient's physical condition and age.

The risks of antiplatelet and anticoagulant

treatment indication antiplatelet or anticoagulant preventive the physician must consider the particular case and the decision must be taken when you are sure that reducing thrombotic risk clearly outweighs the risks associated with these treatments. Both antiplatelet and anticoagulant, but the second, present employment as the main risk of increased incidence of DHF. This danger is today the main factor limiting its use and is higher the older a person so that anticoagulant therapy is indicated with much reserve in the case of older people.

antiplatelet therapy (aspirin in particular) often be at special risk of injury to the gastric mucosa, which can lead to erosive gastritis and even peptic ulcer, although I must say that in recent years have emerged new antiplatelet agents whose use results in a lower frequency of this adverse effect.

There other potential adverse effects as a drug or other choice, but the truth is that the risk of hemorrhage that most concern to doctors. Therefore, the antithrombotic pharmacology research today continues to focus its best efforts to obtain new active compounds with more selective effect on the processes of hemostasis, so that they can get more effective and safer drugs with which to prevent thrombosis without thereby significantly increasing look bleeding risk.

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