How can the assessment of the hemodynamic significance of aortoiliac arterial stenosis by duplex scanning be improved? A comparative study with intraarterial pressure measurement.

PURPOSE

The current diagnostic criteria used to assess the severity of stenoses in the aortoiliac arteries by duplex scanning are mainly based on information related to changes in cross-sectional area and are flow independent. Consequently, duplex scanning fails to detect approximately one quarter of hemodynamically significant aortoiliac lesions compared with intraarterial pressure measurements. The aim of this study is to improve the assessment of the hemodynamic significance of aortoiliac lesions by duplex scanning.

METHODS

A prospective study in 60 patients was performed in which duplex scanning at rest was compared with intraarterial pressure measurements before and after the administration of papaverine. A simplified Bernoulli equation was used to calculate pressure gradients across stenoses (delta PBern). Two flow-related parameters, the increase in peak systolic velocity (delta PSV) across the stenosis and the end-diastolic velocity at the site of the stenosis, were also measured and compared with intraarterial pressure measurements.

RESULTS

delta PBern and delta PSV showed a sensitivity and specificity of 81% and 88%, respectively, for the detection of hemodynamically significant lesions at rest. However, delta PBern could often not give an accurate calculation of the pressure gradient. Receiver operator characteristic analysis showed that a cut-off level for delta PSV in the range of 1.4 to 1.5 m/s was best able to detect significant lesions at rest. The end-diastolic velocity parameter had a limited diagnostic value.

CONCLUSION

Although useful in clinical decision making, delta PBern often could not give an accurate calculation of the pressure gradient. delta PSV is a simple and practical spectral analysis parameter to differentiate between significant and insignificant stenoses. This parameter also has the potential to detect hemodynamically less critical lesions if duplex scanning is performed under conditions of increased flow. Further evaluation is needed.