Venous Thrombotic Disease
If properly treated, superficial thrombophlebitis is a relatively benign condition. However progression to deep vein thrombosis may occur in up to 45% of patients. Patients with a related pulmonary embolism have as much as a 20% death rate.
Recanalization of thrombosed leg veins produces a valveless channel leading to chronically elevated venous pressures and postphlebitic syndrome. The post phlebitic syndrome is characterized by chronic leg pain, swelling, edema, and ulceration. These patients are subject to recurrent episodes of DVT and PE. Superficial venous insufficiency is responsible for nearly all cases of venous ulcerations.
Recent literature advocates an aggressive approach to the diagnosis and treatment of DVT to prevent the disabling longterm sequelae of DVT.
The treatment of DVT typically includes a regimen of anticoagulation including LMW heparin and Warfarin. These agents only prevent additional clot formation and do not effectively treat the existing thrombosis. At least 65% of patients treated with standard heparin anticoagulation develop persistent deep-vein valve incompetence. More than 50% suffer from lifelong CVI (chronic venous insufficiency) with recurrent pain, swelling, ulceration, dermatitis, and DVT recurrence. Up to 80% of patients with a DVT treated with anticoagulants alone will develop a venous ulcer within 10 years. These unfortunate sequelae occur after isolated calf as well as after proximal thrombosis.
Fibrinolytic therapy is advocated as a means to remove abnormal clot and to maintain normal venous valve structure and function if given early enough in the course of the patient’s disease. When compared to heparin alone, follow-up ultrasound showed normal venous studies in three times as many patients and symptomatic CVI in half as many. Evaluation at six years showed a normal venogram was seen in none of the heparin treated patients and 67% had CVI symptoms vs. 41% normal venogram and 24% CVI symptoms in the lytic group.
Lytic therapy produces a more rapid and a more complete reduction in late symptoms and a reduced likelihood of recurrent DVT. Transcatheter infusion of lytic agents directly into the clot is associated with a significantly higher success rate and fewer complications than systemic administration of agent. Complete clot lysis can be achieved without induction of a systemic lytic state in the majority of cases.
Patients who develop tibial, popliteal, or femoral vein thrombophlebitis should be strongly considered for intravenous thrombolytic therapy if the potential risks are judged to be acceptable.
Most cases of DVT are never recognized clinically. Autopsy series show the diagnosis is missed in about 80%. Patients who are at an increased risk for DVT are those with an hypercoagulable state following minor surgery, prolonged travel, bed rest, minor injury or other conditions predisposing the patient to endothelial injury. Patients with venous varicosities are at particular risk for DVT: patients below age 60 years are three times more likely to develop DVT if they have preexisting varicosities.
Patients with a past history of DVT are five times more likely to have a new DVT than those with no previous history. A past history of DVT and PE raises the likelihood of new postoperative venous thrombosis to 100%.
The clinical suspicion of DVT should immediately lead to diagnostic ultrasound assessment. Ultrasound imaging (although neither perfectly sensitive nor specific) is a valuable initial screening tool which is most useful in assessing the veins between the knee and the groin. The skill of the ultrasonographer is of paramount importance in obtaining a reliable and reproducible study. If ultrasound is non-diagnostic, magnetic resonance venography may yield a diagnostic accuracy equal to that of venography.