Complications And Postthrombotic Syndrome

Controversies still exist over the pathophysiology of post thrombotic syndrome. Some authors believe that the primary mechanism is reflux, whereas others think that it is the combination of reflux and obstruction that leads to the most severe symptoms. Johnson studied the natural history of DVT by utilizing duplex ultrasound and demonstrated that the combination of reflux and obstruction were three and a half times more likely in the legs with evidence of post-thrombotic syndrome than in those legs that appeared normal.11 Their findings are also supported by Mohr and his colleagues, who demonstrated a progressive increase in post-thrombotic syndrome over 20 years.9 The highest risk group in their study were those patients under 40 with proximal DVT, who were three times more likely to develop post-thrombotic symptoms than other groups.

Longer duration of venous occlusion has been shown to increase the likelihood of secondary reflux, and thus post-thrombotic syndrome.612 Additionally, the extent of the original DVT, particularly multilevel disease and recurrent thrombosis, has been associated with an increased incidence of post-thrombotic syndrome.13 Techniques aimed at valve preservation and restoration of venous patency theoretically should decrease venous hypertension, thus reducing the incidence and degree of post-thrombotic symptoms. Improvements in venous hemodynamics also should lead to overall improvement in clinical symptoms. In fact, studies have shown that earlier clearance of the clot burden led to preserved valvular function and less symptoms.814

The potential complications of acute DVT include venous gangrene, pulmonary embolism, recurrent thromboembolic events, and the development of chronic venous insufficiency or post-thrombotic syndrome. Anticoagulation therapy, the current standard of care for acute DVT, may inhibit further clot propagation and prevent pulmonary embolism. However, it does not in itself prevent chronic post-thrombotic complications. The consequences of chronic venous insufficiency and post-thrombotic syndrome are a major medical problem and often results in a significant lifestyle compromise for the patient. DVT can render the venous valves incompetent, resulting in a spectrum of clinical presentations ranging from telengectasias and varicose veins through chronic lower extremity pain and edema to venous skin changes with lipodermatosclerosis and ulceration. The incidence of post-thrombotic syndrome following proximal venous thrombosis has been measured at 16 to 82%.3,9 The incidence of ulceration has been estimated at 3 to 8% following DVT. Following extensive lower extremity deep venous thrombosis, the post-thrombotic syndrome may manifest immediately or take several months or years to full patient debilitation.10

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