Venous thromboembolic disease is a condition in which thrombosis (blood clotting) occurs within the main venous system, usually of the legs, and is often combined with the movement of thrombus fragments into the lung, causing pulmonary thromboembolism. Nowadays, we use this term to refer to these two processes which are closely related.
What causes venous thromboembolic disease (VTEE)?
The origin of this disease, which is the third leading cause of death of cardiovascular origin and affects a proportion of 200/100,000 inhabitants in Spain, is linked to predisposing risk factors that can be grouped into two groups:
- The primary ones, which are of hematological cause: protein C, Protein S or antithrombin III deficiency, increased homocysteine, antiphospholipid syndrome, factor V Leiden, alterations in the prothrombin genes, lupus, etc.
- The secondary ones are due to acquired conditions: this happens with obesity, trauma, cancer, sedentary lifestyle, renal or hepatic insufficiency, hormonal treatments, orthopedic, hip or knee surgery, etc. or infections. These pathologies have in common that they cause a venous circulatory situation more prone to the appearance of thrombi (Virchow’s classic triad). In addition, age is one of the most important risk factors.
The dramatic irruption of the SARS-Cov2 virus, origin of COVID-19, in our society, and the frequency with which a significant inflammatory response with activation of procoagulant factors develops, has put this complex system in the spotlight of all research related to this disease.
Significance and symptomatology of TVED
Venous thromboembolic disease (VTED) is serious and potentially fatal. As mentioned above, it is the third leading cause of cardiovascular death after heart attacks and strokes.
The formation of a thrombosis in the main venous system of the legs directly causes a circulatory disturbance characterized by obstruction of the affected veins and thus of the blood drainage system of the limb. Local symptoms progressively appear in the form of:
- Edema
- Swelling
- Change of coloration of the extremity with bluish tinge
- Pain
- Increase in temperature
To this local symptomatology is added the risk that the thrombus or a part of it may fragment, and in its ascent through the venous system, cause the dreaded pulmonary embolism.
At this point, the clinical situation changes abruptly:
- Increased heart rate
- Significant chest pain
- Dyspnea (shortness of breath)
- Cough (may be bloody)
- Change in mucous membrane coloration (darker lips)
- Decreased blood pressure
- Syncope
The endovascular alterations caused by the inflammatory reaction of thrombi in the venous system of the legs, induce hypertension in the tissues that can manifest as edema, cutaneous hyperpigmentation, subcutaneous indurations and ulcers, in what we call postphlebitic sequelae.
People infected by SARS-Cov2 have a higher risk of developing thrombotic phenomena, both during the course of COVID-19 and later, so that a very important part of their mortality is linked to this process.
The passage of time and ongoing studies are continuously providing us with data to better understand its pathophysiology and thus provide patients with better treatment and prevention of this hemostatic situation. One of the main objectives is to identify patients who are potentially more prone to develop VTED or other thrombotic phenomena in relation to COVID-19.
Diagnosis of TVED
Suspicion and clinical examination have a low sensitivity. The determination of high-sensitivity D-Dimer is an important diagnostic method of exclusion, since normal figures practically exclude thrombosis, except in specific cases such as hormone therapy. The diagnosis of deep vein thrombosis (DVT) in the extremities is determined by Doppler ultrasound, where we can directly visualize the existence of the thrombus, its location, characteristics, etc. This examination has a high specificity and sensitivity in cases of inguinal, thigh and calf DVT, decreasing in more distal sectors. In cases of doubt or diagnostic necessity, it can be confirmed with radiological techniques: phlebography, MRI angiography, CT angiography, etc.
Regarding the diagnosis of pulmonary embolism, clinical suspicion should be followed by diagnostic confirmation such as helical CT angiography or V/P scintigraphy, which offer optimal sensitivity and specificity.
Treatment of TEEV
The treatment of VTED is multidisciplinary, depending on the origin and the organs affected.
In any case, the initial standard treatment is anticoagulation with heparin and is an immediate emergency. This has a direct impact on several vital points in the onset of thrombosis and its development:
- We modify the hematological situation prone to thrombosis.
- We stabilize the thrombus, avoid rethrombosis and its displacement (pulmonary thromboembolism).
- We favor collateral circulation, which the circulatory system generates to overcome the obstacle posed by the occlusion of a main vein by the thrombus. In short, we are helping the thrombus to dissolve.
The duration of the treatment depends on many factors, and is determined by the treatment of the condition that has caused the thrombosis. Sometimes, in genetic situations of thrombophilia, anticoagulant treatment is permanent because it is aimed at avoiding new thrombotic events.
There are serious occasions in which this is not enough, and more aggressive treatments must be adopted:
- Venous or pulmonary thrombectomy.
- Treatment with rTPA for cases of unstable pulmonary embolism.
- Removal of clots by endovascular methods…
Finally, in the many cases in which there has been damage to the valves of the venous system, there is what we call postphlebitic sequelae in the lower extremities, which is the set of tissue manifestations in the legs, especially in the area of the ankles on the inner side, caused by the venous hypertension that is generated. The treatment of the limb affected by thrombosis is crucial to avoid or reduce this sequel: hygienic and postural measures, activity, elastic containment, venous tonics, etc.
Postphlebitic ulcers are those that produce the most morbidity and in which we have to adopt continuous measures so that the quality of life of patients is optimal.
Prevention of TEEV
Today we have multiple methods of risk stratification for the prevention of TTEV, for which standardized and personalized prophylaxis guidelines are established, mainly based on the so-called low-molecular-weight heparins and NOACs.
Adjuvant physical methods for prophylaxis have also been shown to be effective almost always in combined treatments: elastic stockings, early ambulation, intermittent pneumatic compressions….
As always, what is important is to identify those people who are susceptible to generating a thromboembolic event based on their individual risk factors in certain circumstances: rest, immobilization, prolonged travel, obesity, dyslipidemia, chronic diseases, COVID-19, etc.