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Impedance analysis versus colour Duplex in femorodistal vein graft surveillance
A H Davies1, T R Magee, M Wyatt
1Department of Vascular Studies, Bristol Royal Infirmary, U.K.
Insights
Non-invasive impedance analysis accurately identifies femorodistal bypass grafts at risk. This simple, quick method offers high sensitivity and specificity, serving as a viable alternative to color Duplex scanning for graft surveillance.
Area of Science:
- Vascular Surgery
- Medical Imaging
- Biomedical Engineering
Background:
- Femorodistal bypass surgery is crucial for limb salvage.
- Effective graft surveillance is essential to prevent complications.
- Current methods like color Duplex scanning have limitations.
Purpose of the Study:
- To evaluate the efficacy of impedance analysis for detecting "at risk" femorodistal bypass grafts.
- To compare impedance analysis with color Duplex scanning and angiography.
- To establish impedance analysis as a reliable non-invasive surveillance tool.
Main Methods:
- Fifty patients undergoing femorodistal bypass surgery were monitored.
- Impedance analysis and color Duplex were used for graft assessment.
- Biplanar intraarterial digital subtraction angiography served as the gold standard.
Main Results:
- "At risk" grafts showed a significantly higher impedance score (0.49) compared to uncomplicated grafts (0.39) (p = 0.003).
- Impedance analysis demonstrated sensitivity and specificity greater than 91% compared to angiography.
- The examination is simple, non-invasive, and takes approximately 10 minutes.
Conclusions:
- Impedance analysis is a highly sensitive and specific non-invasive method for femorodistal bypass graft surveillance.
- It offers a practical and efficient alternative to color Duplex scanning.
- This technique can aid in early detection and intervention for at-risk grafts.
Abstract:
Fifty patients who have undergone femorodistal bypass surgery have been followed up using impedance analysis and colour Duplex, with biplanar intraarterial digital subtraction angiography being used as the arbiter to define "at risk" grafts. An impedance score of 0.49 (0.43-0.55) was found in the "at risk" grafts, all of which underwent an interventional procedure compared to 0.39 (0.36-0.42) (p = 0.003, Mann-Whitney U test) in those with no problem. In total, 166 examinations were performed. The sensitivity and specificity were all greater than 91% when compared to angiography. Impedance analysis is simple, non-invasive, easy to perform and it takes only 10 min to complete the examination. In view of the results obtained using impedance analysis in comparison with Duplex scanning, we suggest that non-invasive impedance is a suitable alternative to colour Duplex for graft surveillance (mean +95% confidence interval).