[Algorithm of ultrasonographic examination of patency of venous stents]

Analysed in the article are the results of ultrasonographic examination of patency of venous stents implanted in 86 patients with obstructive lesions of the iliofemoral segment of deep veins. The authors proposed an algorithm of triplex scanning, making it possible to optimize ultrasonographic examination, as well as increasing the accuracy of assessing the state of the stent and patency of the stented segments of veins. The first stage was to examine the state of the stented venous segment in the mode of grey-scale scanning (B-mode), for which purpose the study was performed in the longitudinal and transverse projections. This made it possible to determine the qualitative state of the stent as either presence or absence of its migration and deformation, completeness of expansion, extravasal compression. The second stage was to locate the venous stent in the mode of colour Doppler mapping (CD-mode), thus making it possible to assess stent patency. The third stage was examination in the spectral Doppler mode with the use of the distal compression test. Ultrasonographically detected phasic, respiration-synchronized blood flow with an increase of its linear velocity proximal to the stent in distal compression (positive compression test) is suggestive of no obstructive alterations in the stent's lumen. Determination of the blood flow velocity makes it possible to evaluate the stent patency or stenotic alterations. Monophasic low-velocity blood flow in the ipsilateral common femoral artery may also be indirectly indicative of impaired stent patency (pronounced stenosis, thrombosis, occlusion). The proposed algorithm of ultrasonographic triplex study of patency of venous stents may be used in out-patient conditions repeatedly and safely for the patient.