Duplex-Derived Maximum Venous Outflow Velocity (MVOV) of the Common Femoral Veins is Asymmetric in Normal Women

Abstract

Background

It is generally accepted that a significant portion of our population harbors asymptomatic compression of the left iliac vein by the right iliac artery. This was demonstrated originally in autopsy studies by McMurrich in 1908 (33% of 107 cadavers) and more recently by the analysis of Contrast CT scans 1 (66% of 50 patients). Authors have found that Venography may lack the sensitivity to be considered a true “gold standard” (66% sensitive) while IVUS is over 90% sensitive 2. No studies have addressed the physiologic difference in flow hemodynamics between the left and right lower extremities in normal individuals. We use Doppler ultrasound to demonstrate asymmetric flow in the lower extremities of normal individuals.

Methods

Maximum venous outflow velocity (MVOV) in the Common femoral veins were recorded using Doppler ultrasound on 30 volunteers. Inclusion criteria included age 18–30, BMI <30, female sex and no history of venous disease or leg swelling. All studies were preformed by the same experienced vascular technologist. Volunteers were instructed to lay supine while a blood pressure cuff was inflated to 100 mmhg around the mid-thigh. Presence of arterial flow was confirmed with color duplex after cuff inflation. Prior to rapid cuff release at 1 minute patients were instructed to exhale and hold their breath to augment venous outflow. Flow velocities in the left and right common femoral veins were recorded.

Results

The average age was 20.9 years (range 19–28 years) and the average BMI was 21.9 (range, 18–25). MVOV was slower on the left side in 22, slower on the right in 7 and equal in one volunteer. The mean right MVOV was 117.23 cm/sec, SD 46.95 and the mean left MVOV was 95.44 cm/sec, SD 32.94 (P = 0.0095). There was no correlation between left and right MVOV with respect to age, BMI or height.

Conclusions

Significant differences in lower extremity venous flow are present in normal individuals at rest. This finding correlates with anatomic studies demonstrating a predilection towards narrowing of the left iliac vein in normal subjects. This simple, non-invasive method of quantifying venous hemodynamics may aid in selecting patients for further diagnostic testing or intervention.