Alveolar echinococcosis of the liver - Sequelae of chronic inferior vena cava obstructions in the hepatic segment

Background: The clinical pattern and long-term course of chronic inferior v ena cava (IVC) obstructions are variable and depend on the underlying cause , the segment involved, and the extension of secondary thrombosis. Pertinen t data on IVC obstructions in well-defined series of patients are lacking. We report the sequelae of chronic IVC obstructions in the hepatic segment i n 11 consecutive patients derived from a cohort of 104 patients with alveol ar echinococcosis of the liver. Methods: Based on the results of computed tomography scans, 11 patients (7 men, 4 women; mean age, 53.4 years) with IVC obstructions were selected fro m an ongoing prospective long-term chemotherapy trial comprising 104 patien ts with alveolar echinococcosis studied at yearly intervals according to a protocol. Obstruction of the IVC in the 11 patients existed for a mean dura tion of 8.6 years. In these patients, magnetic resonance imaging was perfor med to assess the morphologic features and extension of the IVC obstruction , as well as the collateral venous pathways. Patency and valvular function of the femoropopliteal veins were analyzed by color-coded duplex ultrasonog raphy. Results: Total occlusions of the IVC were evident in 8 patients (73%) and s ubtotal stenoses in 3 patients (27%). Only 4 patients (36%) exhibited signs and symptoms of chronic venous insufficiency of the lower extremities; 2 ( 18%) of the 4 had a history of swelling in the lower extremity. Seven patie nts (64%) had no lower extremity symptoms. One patient had a history of pul monary embolism. Abdominal collateral veins were documented in 5 patients ( 45%) by using magnetic resonance imaging; however, they were clinically evi dent in only 3 patients (27%). In the 8 patients with IVC occlusion, thromb osis ended at the confluence of the hepatic veins. Obstruction of the IVC w as limited to the hepatic segment in 2 patients (1.8%) and extended to the distal IVC or the iliofemoral veins in 6 patients (54%). Chronic venous ins ufficiency was present only if the femoropopliteal veins had been involved in the thrombotic process, showing residual venous obstruction, valvular in competence, or both. Bilateral renal vein thrombosis with moderate proteinu ria was observed in 2 patients (18%). The main collateral drainage was achi eved through the ascending lumbar, azygos, and hemiazygos veins. Conclusions: In patients with alveolar echinococcosis, obstruction of the I VC in the hepatic segment often develops asymptomatically and rarely leads to the impairment of renal function. The collateral circulation fully compe nsates for obstruction of the IVC. Thrombotic involvement and valvular inco mpetence of the femoropopliteal veins seems to determine the development of chronic venous insufficiency of the lower extremities.