What is the pathophysiology of DVT?
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In brief this is pathophysiology of DVT:
PATHOPHYSIOLOGY
Deep Vein Thrombosis
Venous thrombi typically develop within a deep vein at a site of vascular trauma and in areas of sluggish blood flow (eg, in the venous sinuses of the calf and within a valve cusp). An accumulation of fibrin and platelets causes rapid growth in the direction of the blood flow, potentially reducing venous return. Endogenous fibrinolysis results in a partial or complete resolution of the thrombus. Residual thrombus will organize and the vein may incompletely recanalize, which often results in narrowing of the lumen and valvular incompetency. An extensive collateral network can develop.
Pulmonary Embolism
Thrombi that embolize to the lungs will lodge within either the lobar arteries or the distal main pulmonary artery; occasionally they will straddle the pulmonary artery bifurcation (saddle embolus). Smaller thrombi can travel more distally. A pulmonary embolism causes several physiologic changes. Stimulation of irritant receptors causes alveolar hyperventilation, which increases the respiratory rate. Gas exchange becomes impaired because the affected lung tissue is ventilated but not perfused. Initially, this alveolar "dead space," and later the development of intrapulmonary shunting, causes bronchoconstriction and hypoxemia. Atelectasis and edema caused by the loss of alveolar surfactant can develop within hours. A decrease in the cross-sectional area of the pulmonary arterial bed, hypoxia, and the release of humoral factors by activated platelets (eg, serotonin and thromboxane) increase pulmonary vascular resistance. Even so, an acute embolic event in a healthy individual will not generate a mean pulmonary artery pressure greater than 40 mm Hg.4 Pulmonary hypertension can result in right ventricular failure and, infrequently, decrease cardiac output. The severity of hemodynamic compromise, and hence symptoms, is dependent on the extent of arterial obstruction and the presence or absence of pre-existing cardiopulmonary disease.
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Most DVT's disappear without a problem, but they can recur. Some people may have chronic pain and swelling in the leg, known as post phlebitic syndrome. Pulmonary embolus is uncommon when DVT's are treated properly, but it can occur and can be life threatening.
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