Venous outflow obstruction: An underestimated contributor to chronic venous disease.

OBJECTIVE: To assess the importance of iliac venous outflow obstruction in limbs with and without concomitant deep or superficial reflux, we performed a retrospective analysis of data contemporaneously entered into a set time-stamped electronic medical records program. MATERIAL AND
METHOD: Four hundred forty-seven limbs underwent iliac vein stenting of chronic, nonmalignant obstruction when greater than 50% morphologic stenosis was found at transfemoral venography or intravascular ultrasonography. Group 1 (female-male ratio, 3.4:1; left limb-right limb, 2.7:1; nonthrombotic-thrombotic, 1.8:1) included 187 stented limbs in 176 patients with absence of deep and superficial reflux as identified at erect duplex Doppler scanning. Group 2 (female-male, 1.7:1; left-right, 1.9:1, nonthrombotic-thrombotic limb, 1:2.1) included 260 limbs in 253 patients with combination obstruction and reflux. Reflux was left untreated during the observation period. Clinical outcome (ulcer healing and recurrence rate, degree of pain per visual analog scale, swelling grade) and hemodynamic effects (ambulatory venous pressure, venous refilling time, venous filling index at 90 seconds) of iliac venous stenting were assessed. RESULT: Patients with reflux and obstruction had more severe disease (clinical class 4-6, 53% in group 2 vs 24% in group 1; P <.001). Similarly, rate of active ulcer was low in limbs with obstruction only (3% vs 24%, groups 1 and 2, respectively). Mean clinical follow-up was 13 +/- 12 months (SD) in 86% of limbs. Because of the presence of reflux in group 2, venous pressure was higher, venous filling time was shorter, and venous filling index at 90 seconds increased, compared with group 1. Multisegment scores were 2.6 +/- 1.6 and 0, respectively. Of greater interest, there was no deterioration in venous hemodynamics in group 2 after stenting. There was substantial clinical improvement in both groups after stenting. Approximately half of patients were completely relieved of pain after stenting, and a third were completely relieved of swelling. In addition, 55% of ulcerated limbs healed.
CONCLUSION: Iliac venous outflow obstruction appears to have an important role in clinical expression of chronic venous insufficiency, particularly in producing pain, and is easily overlooked, mainly because of diagnostic difficulty. The combination of reflux and obstruction is seen more frequently with severe clinical disease than is obstruction alone. Ulcer prevalence is clearly associated with reflux, with a low incidence in patients with obstruction alone. Removal of iliac vein outflow obstruction does not result in increased axial reflux, with clinical deterioration in limbs with combined reflux and obstruction.