Horne and Chang present the case of a young man with metastatic colon cancer who developed an acute deep venous thrombosis (DVT) of the lower extremity. Symptoms from the DVT were severe enough that the patient was bed-bound and were not improved with heparinization. Recombinant tissue-type plasminogen activator (rtPA) was injected along the course of the thrombus, with partial relief of symptoms. A second dosage of rtPA was injected in a similar manner, with marked improvement of symptoms. Subsequent anticoagulation with warfarin was accomplished.
Since the early 1990s, catheter-directed infusion of rtPA has become a typical method of thrombolysis. A four-day infusion of urokinase has been an accepted treatment, and most (80 percent) of the patients who receive this treatment are found to have at least a 50 percent resolution of the thrombus. The cost of urokinase therapy, however, is quite high, and justifying its use (instead of low-molecular-weight heparin therapy, another standard treatment for acute DVT), is difficult. Heparin or low-molecular-weight heparin gives adequate results (e.g., symptomatic relief and decreased risk of pulmonary embolism), but recurrent DVT is not uncommon. Also, DVT complications, which may be caused by systemic hypercoagulability and damage to the venous valves, may occur.
In the case presented, an immediate benefit from thrombolytic therapy was seen. The authors question whether rtPA can reduce the risk of the development of chronic complications of acute DVT. Rapid thrombolysis seems to preserve the function of the venous valves; this is not always the case when traditional anticoagulant therapy is used. The question then becomes, “Which patients will benefit most from thrombolytic therapy without suffering undue risk or cost?” The answers to this question will be based on the factors such as the patient's prognosis, underlying diseases, concomitant symptoms, risk of hemorrhage and age of the DVT.
The authors conclude that there is insufficient evidence to recommend use of thrombolytic therapy for treatment of acute DVT, although they pose questions to help guide this decision (see the accompanying table). Randomized clinical trials are clearly needed to help physicians decide whether to use thrombolysis instead of anticoagulation alone.