The development of valvular incompetence after deep vein thrombosis: a follow-up study with duplex scanning

Duplex ultrasonography with distal cuff deflation was used to establish the physiologic reflux duration in different segments of the deep venous system in healthy individuals, and to document the occurrence of deep vein valve incompetence in patients after deep vein thrombosis (DVT).

Two hundred fifty-two vein segments in 42 legs of 21 healthy individuals and 160 deep vein segments in 27 patients with phlebographically documented DVT were examined with duplex scanning.

The duration of reflux in healthy subjects was significantly shorter in distal deep vein segments. Ninety-five percent of the values were less than 0.88, 0.8, 0.8, 0.28, 0.2, and 0.12 seconds, respectively, for the common femoral, superficial femoral, deep femoral, popliteal, and posterior tibial vein (at midcalf and ankle level). The 95 percentile for reflux duration in the superficial venous system was 0.5 seconds for all vein segments, regardless of the location. No significant correlation was found between the reflux peak flow velocity and reflux duration (R = 0.6). The reflux peak flow velocity is therefore not useful as a parameter of the degree of reflux. The patient group was examined with an interval of 18 to 51 months (mean 34 months) after DVT. Forty-five percent of the initially affected segments showed valve incompetence at follow-up (n = 54); only three of 40 segments initially free from thrombus showed pathologic reflux at follow-up (p < 0.01). Reflux durations in most of the incompetent vein segments were two or more times the normal value of reflux duration. The highest prevalence of valve incompetence was found in the superficial femoral and popliteal vein segment (p < 0.01). None of the patients showed valve incompetence at all levels of the deep venous system. A significant (p = 0.04) relation was found between the extent of the initial thrombosis and the number of refluxing vein segments at follow-up, but no correlation was found between the extent of initial thrombosis and the late clinical symptoms (p = 0.16); clinical symptoms could not be related to the number of incompetent vein segments.

Duplex scanning allows a good discrimination between physiologic and abnormal reflux duration and is an important tool in the evaluation of the postthrombotic limb. Early assessment after DVT may have prognostic value in individual patients.