Venous Disorders Pathophysiology
The diseases of the veins of the lower extremities are an extremely common and serious problem. While chronic manifestations significantly worsen the quality of life, acute problems can be life-threatening. In this way, there is a need to describe the mechanisms of development of venous insufficiency and deep vein thrombosis by taking into account such an important factor as a patient's age.
The most serious disease is deep vein thrombosis, the mechanisms of occurrence of which are well studied. In accordance with modern concepts, the role is played by all or several factors from the Virchow triad. Hypercoagulation (can be caused by both thrombophilia and certain medications, paraneoplastic syndrome, and a number of other factors) and blood stasis (due to the lack of muscle-venous pump) are background factors of this condition (Connors, 2017). A provoking factor is often a vein injury, for example, fractures. At the same time, in most cases of venous thrombosis, there was no traumatic effect on the vein, but the first two factors were revealed (during long-term operations under general anesthesia, especially in trauma, oncological and cardiovascular patients). The greatest role in the development of venous thrombosis is played by the coagulation unit of hemostasis (coagulation factors and fibrinolysis system). The occurrence of arterial thrombosis mainly initiates the thrombocyte link (platelet aggregation at the site of damage to the artery or instability of an atherosclerotic plaque). In the veins, blood clots begin to form mainly in the sinuses under the venous valves, which should move the “pillars” of blood towards the heart. The most dangerous complication is the fragmentation and separation of a thrombus as well as embolization into the pulmonary artery.
Chronic venous insufficiency may develop due to two pathophysiological mechanisms. The first is a vein obstruction. In the case of previously transferred venous thrombosis as well as absence of adequate prolonged anticoagulant therapy, recanalization of the deep veins does not occur. Such condition is called postthrombotic syndrome. Another option is the development of reflux (often in the system of superficial saphenous veins, less often - deep veins). It arises due to a malfunction of the venous valves, which should prevent the backflow of blood through the vein under the influence of gravity. If a valve fails, this process does not occur, and venous hypertension develops in the limbs (Mannello & Raffetto, 2014). It leads to impaired microcirculation in the skin, increased capillary permeability, penetration of red blood cells into tissues, and disintegration with the deposition of hemosiderin, hence provoking an inflammatory reaction from macrophages, which supports the release of cytokines and damage to surrounding tissues. Ultimately, venous ulcers develop due to degeneration and tissue necrosis or lipodermatosclerosis due to increased collagen production by fibroblasts in order to replace the affected cells.
Such factor as age is a serious risk parameter for the onset of chronic venous insufficiency (due to prolonged exposure to provoking and predisposing factors) and deep vein thrombosis (M?an et al., 2013). With regard to the latter, the main factor that is more common in the population of elderly patients is the immobilization of the limb due to injuries of the musculoskeletal system, various arthrosis, and arthritis that very often occur in old age. Blood stasis belongs to the Virchow triad by taking into account the risk of coagulation disorders (more often not primary, such as thrombophilia, but secondary, such as malignant tumors, autoimmune diseases, myeloproliferative diseases, and many others). It must be taken into account in order to adequately prevent this condition before surgery (adequate dosages of anticoagulants, elastic stockings, or pneumatic compression) as well as during the treatment of an already occurring deep vein thrombosis (Wittens et al., 2015). It is necessary to identify possible underlying causes, oncoscreening, or genetic testing in case of clinical suspicion of the above diseases (Timp, Braekkan, Versteeg, & Cannegieter, 2013). As for chronic venous insufficiency, valve function also deteriorates with age, especially under the influence of lifestyle, such as obesity, which disrupts the function of the muscle pump and significantly aggravates reflux and clinical symptoms of the disease. In addition, with age, valve dysfunction (disruption of elastin structure) and insufficiency during closing of the valves develop under the influence of various pro-inflammatory and genetic factors. It may affect the choice of therapy, as in elderly patients, conservative methods may be ineffective due to pronounced anatomical changes, which requires ablation of the affected veins.
In this way, the mechanisms of deep vein thrombosis and chronic venous insufficiency are complex and not studied in detail. The main role is assigned to the factors of the Virchow triad in the first and obstruction or reflux in the veins in the second case. A factor, such as old age, can provoke and predispose to both conditions mainly due to a decrease in the mobility of elderly patients.
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Proximal
Swelling of the whole limb
Fever
Positive signs of Homans and Moses
Frequency 1: 1000 people per year
Among hospitalized patients with severe injuries of the spinal cord and the musculoskeletal system is estimated from 40 to 80%
Every year, about 100,000 people in the United States die from thromboembolism.
Epidemiology
Blood stasis (immobilization)
Deep vein thrombosis
Clinical signs
Distal
Asymptomatic
Swelling below the knee
Positive signs of Homans and Moses
Pathophysiology
Triad of Virchow
Hypercoagulation (primary - thrombophilia and secondary - paraneoplastic, autoimmune)
Endothelial trauma
Diagnostics
Treatment
Ultrasound
(lack of blood flow in the lumen of the veins,
intraluminal formations, incompressibility of the veins in the compression test)
Laboratory tests
(D-dimer, genetic testing for thrombophilia)
Anticoagulation
Thrombolysis
Endovascular thrombo-aspiration or surgical thrombectomy in very special cases.
Figure 1. Mind map for deep vein thrombosis
In different countries, 25 to 50% of people have symptoms.
Most common in older age groups from 50 to 70 years.
1 out of 300 adults have venous ulcers.
Epidemiology
Obstruction (postthrombotic disease)
Subjective
(swelling of the lower extremities, night cramps, heaviness in the legs)
Chronic venous insufficiency
Clinical signs
Pathophysiology
(Underlying reason)
Reflux (varicose veins)
Venous hypertension
Objective
(hyperpigmentation, lipodermatosclerosis, trophic ulcers)
Microcirculation disorders
Trophic changes on the skin
Obstruction
Bypass surgery
Diagnostics
Treatment
Ultrasound procedure
Conservative
Compression stockings
Phlebotonic drugs
Reflux
Open surgery (crossectomy and stripping)
Endovenous procedures (laser or radiofrequency ablation, sclerotherapy)
Obstruction
Phlebography if necessary
Reflux
Duplex study with Valsalva maneuver