Thrombosis is caused by the formation of blood clots in blood vessels, the formation of which hinders the normal circulation of blood. Thrombi can also fragment and reach, in the form of embolisms, different parts of the body, causing pathologies such as myocardial infarction, stroke (cerebral infarction) or pulmonary embolism.
The thrombosis rarely felt, even if it is potentially lethal. A recent survey by the Association for the Fight against Thrombosis and Cardiovascular Diseases (ALT) showed that thrombotic diseases are known by about 30% of Italians.
In fighting this disease it is essential to know the risk factors and the signals that should not be underestimated. As Dr. Corrado Lodigiani, Head of the Thrombosis and Hemorrhagic Diseases Centre of Humanitas, explains: “The earlier the diagnosis, the more timely the appropriate therapy is set up, the more effective is the treatment of the acute event and of the most serious and potentially fatal complications, such as pulmonary embolism in the case of a patient with venous thrombosis”.
Deep vein and surface thrombosis
Thrombi can form in an artery (arterial thrombosis or heart attack) or in a vein. If the formation takes place in a deep vein, it is referred to as deep vein thrombosis, whereas if a vessel of the superficial venous circle is affected, it is referred to as superficial venous thrombosis (also commonly known as thrombophlebitis).
“It is mainly the lower limbs that are affected because of stasis and standing, although any vein can be affected, even the veins of the brain, abdomen or eye,” says Dr. Lodigiani.
Signs that should not be underestimated
“Venous thromboembolism is often not very symptomatic and it is therefore difficult to recognize early on, so it is only detected when complications have already occurred. In other cases the symptoms are clearer and more specific. Examples include increased volume, pain, but also redness and a feeling of skin heat in the affected limb. The combination of all these symptoms must immediately lead one to think of a venous thrombosis, which must be rapidly diagnosed or excluded by ultrasound scanning”, recommends Dr. Lodigiani.
Embolisms, or fragments, that can reach the lung can also be detached from the venous thrombus: “The main symptom of the pulmonary embolism is a sudden difficulty in breathing (called dyspnea), particularly under stress (for example when walking or running) but also at rest. Chest pain is another symptom, and it can also occur, albeit less frequently, as a result of coughing up blood sputum. Finally you may experience an arrhythmia, which can be so severe as to lead to sudden death,” stressed the specialist.
The causes of the formation of clots
Atherosclerosis is the main mechanism of arterial thrombosis; atherosclerosis is characterized by the formation of deposits of atherosclonic plaque along the walls of the arteries and precisely at these plaques blood clots can form that cause the acute occlusion of the affected vessel and thus thrombosis. Hypertension, hypercholesterolemia, overweight, obesity and cigarette addiction, the so-called environmental cardiovascular risk factors, are associated with atherosclerosis.
The tendency to the formation of clots in the venous system can be related to a predisposing genetic condition, which generally determines hypercoagulability, or a tendency of the blood to coagulate more. In most cases, however, the probability of thrombotic events, even in genetically predisposed subjects, increases in the presence of other risk factors. Some of these are considered modifiable because they are associated with lifestyle, such as sedentariness or an incorrect diet that leads to an accumulation of excess body weight or an increase in blood cholesterol levels.
Also associated with venous thrombosis are prolonged and forced immobility, as happens to hospitalized people, having undergone surgery, pregnancy, and patients with the presence of a chronic inflammatory disease or a tumor.
The intake of oral contraceptives is also linked to a higher risk of thrombosis: “These drugs reduce the levels of proteins that keep the blood more fluid (anticoagulant proteins). The intake of contraceptives by women with genetic predisposition to thrombosis, who are obese or overweight and dependent on cigarette smoke, exposes them to an even greater risk,” emphasizes Dr. Lodigiani.
Latest generation formulations are related to a higher risk: “Compared to previous ones, third and fourth generation formulations contain a higher estrogen and progestin level and this risk is not reduced in transdermal formulations (patches). It is therefore advisable to use these contraceptives with caution if women are smokers, obese or overweight and especially if they have family history with thrombotic events; only in women with family history with or who have already had vascular events should tests (thrombophilia screening) be carried out to document the presence of abnormalities that may weigh on the risk of thrombotic events, before taking oral contraceptives”, concluded the specialist.