J Korean Surg Soc JKSS Journal of the Korean Surgical Society 1226-0053 The Korean Surgical Society 10.4174/jkss.2009.77.6.404 Original Article Left Iliac Vein Compressions and Venous Hemodynamic Changes Lee Chung-Heon M.D. Jang Lee-Chan M.D. Sun Woo-Young M.D. Park Jin-Woo M.D. Choi Jae-Woon M.D. Department of Surgery, College of Medicine, Chungbuk National University, Cheongju, Korea. Corresponding author (icjang@chungbuk.ac.kr) 12 2009 04 12 2009 77 6 404 409 18 07 2009 22 09 2009 Copyright © 2009 The Korean Surgical Society 2009 Purpose

Left iliac vein compression is a risk factor for deep vein thrombosis (DVT) and often can be symptomatic. We wanted to know the incidence of left iliac vein compressions in the general population and the relationship between iliac vein compression and outflow fraction of the lower extremities.

 Methods

1,523 cases examined with abdomen - pelvis CT were included in this study. Left iliac vein compression was calculated as the diameter of left common iliac vein at the site of maximal compression divided by the diameter of the uncompressed caudal common iliac vein. These cases were divided into 4 groups by the degree of iliac vein compression. In addition, left lower extremity venous outflow fractions in 106 patients with abdomen - pelvis CT images were recorded and analyzed.

 Results

The number and mean age of each group (group 1, 2, 3 and 4) were 351 (23%) & 62.3±13.4, 426 (28%) & 57.7±16.1, 529 (35%) & 50.1±20.4 and 217 (14%) & 40.7±22.9, respectively. While the age of patients was decreasing, the occurrence of left iliac vein compression increased (P<0.01). The mean left low extremity venous outflow fractions of each group (group 1, 2, 3 and 4) was 27.9±6.9%, 26.9±6.4%, 25.9±6.7% and 19.1±6.6%, respectively. The mean outflow fraction of group 4 was significantly lower than that of other groups (P<0.01). There was a tendency that the more left iliac vein compression increased, the more outflow fraction decreased (P=0.011).

 Conclusion

In 14% of 1,523 cases, there were severe left iliac vein compressions, more than 75% diameter, and the mean outflow fraction of that was lower than in others. Further study is needed to realize the relationship between left iliac vein compression and DVT.

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Example of outflow fraction. MVO = maximum venous outflow per 1 second, equal to V1; SVC = systemic venous capacitance, equal to V; Ratio = equal to outflow fraction.

Axial images of left iliac vein compression in abdomen-pelvis CT.

Correlation of age and Lt. iliac vein compression. Pearson's correlation is -0.363 between age and iliac vein compression (P<0.01) (R2=-0.1318).

The mean outflow fraction of group 4 was significantly lower than that of other groups (P<0.01).

Correlation of outflow fraction and Lt. iliac vein compression. Pearson's correlation is -0.246 between outflow fraction and compression rate (P=0.011) (R2=-0.0607).

Mean age and mean compression of left iliac vein

Mean compression of Lt. iliac vein between male and female group

Mean outflow fractions of each group

*Mean outflow fraction of group 4 is significantly lower than other groups.