Anomalous features of iliac vein stenosis that affect diagnosis and treatment.

Abstract

Endovenous management of venous lesions is largely derived from arterial experience. However, venous lesions, particularly iliac vein stenoses, differ from their arterial counterparts in some crucial respects. Awareness of these differences is necessary for proper diagnosis and treatment. This report expands on three such anomalous features that we have noted previously in anecdotal form: (1) a unique form of a long and diffuse stenosis (Rokitansky stenosis) that may escape diagnosis with conventional techniques; (2) the invariable failure of plain old balloon angioplasty (POBA) to relieve iliac vein stenosis (both focal and diffuse); and (3) the stent compression by venous strictures, whether focal or diffuse, extrinsic to the stent. Although these features are somewhat interrelated from the concentric fibrous structure of iliac vein stenosis, they represent different phases in the overall management of iliac vein lesions. The analyses are derived from electronic medical records of 2534 iliac vein stent procedures performed from 1996 to 2013. Smaller subsets were used to record more detailed intravascular ultrasound planimetry data than were available in the generic database. The incidence of Rokitansky stenosis without focal lesions was 1.5%. After POBA, stenotic area increased from a median of 60mm(2) to 62mm(2), a miniscule improvement. Lumen area increased to a nearly "normal" 172mm(2) afterstent placement. In 103 limbs with residual or recurrent symptoms, in-stent restenosis (ISR) was present in all limbs; additional stent compression was evident in 25% of the limbs, adding to the overall severity of the stenosis. ISR responded well to high-pressure balloon dilation, with total clearance in 62% of treated limbs andsubstantial improvement in others. In contrast, stent compression was resistant, remaining unchanged in 68% after balloon dilation. Rokitansky stenosis is easily missed with conventional diagnostic techniques and may not be recognizable even with intravascular ultrasound, unless routine planimetry is used. POBA as a primary treatment invariably fails to correct focal or diffuse iliacvein stenosis, and stenting is always required. Stent compression is a unique feature of iliac vein stenosis, whether it is focal or diffuse. It often occurs in association with ISR, when overall stenosis can be underestimated if stent compression is not taken into account. Stent compression responds poorly to balloon dilation, whereas the associated ISRshows complete clearance in the majority of treated limbs.