Influence of popliteal vein thrombosis on subsequent ambulatory venous function measured by near-infrared spectroscopy

BACKGROUND: To determine the influence of the site affected by thrombi on the subsequent venous physiology, we examined patients with postthrombotic syndrome (PTS) with respect to ambulatory venous function using near-infrared spectroscopy (NIRS). METHODS: Fifty-one limbs of 45 patients, for whom more than 1 year had passed since an acute episode of deep vein thrombosis, were studied. Seventeen limbs were asymptomatic, 27 had mild symptoms (edema only), and 7 showed severe symptoms (skin changes). The mean duration of PTS was 8.2 years. All of the patients underwent a treadmill walking test with simultaneous NIRS. Deoxygenated hemoglobin was continuously measured during exercise. The ambulatory venous retention index (AVRI) obtained from the serial deoxygenated hemoglobin changes was calculated in each patient. The location of thrombi at the onset of deep vein thrombosis was identified by venography. RESULTS: The calculated AVRI was apparently related to the clinical symptoms of PTS. The limbs initially involved with popliteal vein thrombosis showed significantly higher AVRI values than those without popliteal vein thrombosis. CONCLUSIONS: The clinical severity of PTS is correlated well with the degree of venous retention during exercise. Initial involvement of the popliteal vein is an important factor determining subsequent venous hemodynamics in patients with PTS.