SUBCLAVIAN VASCULAR ACCESS STENOSIS IN DIALYSIS PATIENTS - NATURAL-HISTORY AND RISK-FACTORS

Stenosis of the subclavian vein (SVS) after cannulation occurs in 15 t o 50% of chronic hemodialysis patients, and impedes the placement of a n arteriovenous fistula in the ipsilateral arm. Its natural history an d pathogenic mechanisms are not well established. This study examined 42 consecutive chronic renal failure patients (28 men and 14 women; 46 +/- 19 yr) in whom subclavian catheters had been placed as the initia l vascular access for hemodialysis. All patients underwent sequential venography studies: at baseline (24 to 48 h after removal of the cathe ter) and 1, 3, and 6 mo thereafter. Venograms were considered abnormal when there was evidence of unequivocal strictures (more than 30% narr owing), with or without collateral circulation. At baseline, 52.4% (n = 22) of patients showed stenotic vein lesions (n = 19) or total throm bosis (n = 3), and identical lesions were also observed after 1 mo. Su rprisingly, 10 of 22 patients with initial SVS (45.4%) showed spontane ous recanalization of venous lesions in the venographies performed 3 m o after removal. The patients with normal baseline venograms (n = 20) showed no change during follow-up. Patients with definitive stenosis a t 6 mo (n = 12) had a higher number of inserted catheters (1.58 +/- 0. 6 versus 1.2 +/- 0.48; P < 0.05), longer time in place (49.08 +/- 32.2 versus 29.03 +/- 26.6 d; P < 0.05), and higher number of dialysis ses sions (21 +/- 13.8 versus 12.4 +/- 11.4; P < 0.05) than those without SVS or with spontaneous recanalization of venous lesions during follow -up. Furthermore, a higher number of catheter-related infections were observed in patients with definitive SVS (66.6% versus 33.3%; P < 0,05 ). In summary, SVS is observed in more than half of patients 24 to 48 h after catheter removal and 1 mo later. Even when recanalization occu rs in many cases, a definitive stenosis is seen in 28% of patients by the third month. Thus, the creation of an ipsilateral vascular access is possible provided that venography is normal at this time. Finally, mechanical factors and catheter-related infections are the major risk factors for the development of late SVS.