Based on the results of a retrospective, single-centre cohort study conducted at The RANE Center, St Dominic’s Memorial Hospital (Jackson, Mississippi, USA), the importance of intravascular ultrasound (IVUS) for identifying the location and severity of stenotic lesions in the iliac vein has been affirmed. Findings of a blinded comparison between IVUS and venography showed that the former is superior as a method of determining treatment zones for iliac vein stenting.
Commenting on the research, which was recently published in the Journal of Vascular Surgery: Venous and Lymphatic Disorders, lead author Myriam Montminy (Jackson, Mississippi, USA) said: “Adequate assessment of the location and degree of stenosis, and delineation of venous anatomy for optimal landing zones, are key elements in the success of interventions to treat chronic obstructions of the deep venous system.”
“While venography is more accessible and less expensive to perform than IVUS,” as Montminy explains, “an increasing number of studies demonstrate that IVUS is significantly more sensitive than venography in identifying stenotic lesions in the iliac-caval segments”. Following on from these investigations, the study conducted by Montminy and colleagues at St Dominic’s Memorial Hospital aimed to compare these modalities “in identifying the key parameters required to guide stent placement”.
Led by senior investigator Seshadri Raju, cases were analysed from the period between October 2013 and November 2015, with 155 limbs (152 patients) counted as having undergone an endovascular intervention for chronic iliofemoral vein stenosis. Furthermore, both venography and IVUS were conducted in all of the cases utilised as part of the study.
Venography and IVUS data from these cases were reviewed by vascular surgeons and radiologists, who were blinded to each other to identify the location and severity of maximal stenosis, location of iliac-caval confluence, and optimal distal landing zone, before comparison. In addition to this, maximal stenosis was defined as the most severe stenosis found among the common iliac vein, external iliac vein, common femoral vein, and infrarenal vena cava.
Key demographics of the series were also included in the research: patients analysed had a mean age of 59 years, 30% involved male patients, and 61% of limbs treated were the left leg. Also, 72% of the patients included in the study were post-thrombotic.
Results of the study demonstrated a failure of venography to identify lesion existence in 19% of limbs, while the median maximal area stenosis was significantly higher with IVUS than with venography (69% vs 52%; P<.0001). It was also found that venographic correlation with IVUS for the anatomic location of maximal stenosis was present in only 32% of the limbs. In terms of iliac-caval confluence, location on venography only correlated with IVUS in 15% of patients and, in 74%, was located higher with IVUS than with venography. Finally, correlation between venography and IVUS on location of the distal landing zone was only 26%.
Commenting on these findings, which suggest that IVUS is the better diagnostic and procedural tool in iliac-caval stenting, Montminy stated: “This study highlights that venography compared to IVUS is likely to be deficient in all three areas of concern in venous stenting cases – location of the maximal stenosis as well as the optimal proximal and distal landing zones.”
On the other hand, it was confirmed by Montminy that venography remains a valuable adjunct in iliac vein stenting, as it provides a panoramic view of the pathologic process. “Additionally, IVUS may miss or provide only a partial image of certain lesions situated at the hypogastric-iliac and iliac-caval confluences due to the absence of a centring mechanism,” she argued.
Although there is no evidence yet to confirm whether the superiority of IVUS in identifying key parameters essential for iliac vein stenting would improve clinical outcomes, the cohort study conducted by Montminy et al was able to “further define the complementary roles venography and IVUS play in this growing area of vascular intervention”.