Postoperative Color Flow Duplex Scanning in Aortic Endografting

Abstract

Purpose: To report the feasibility and sensitivity of duplex sonography compared to computed tomography (CT) for aortic endograft follow-up surveillance. Methods: In a 26-month period, 113 aortic aneurysm patients received 79 tube and 34 bifurcated stent-grafts. Follow-up used contrast-enhanced CT scanning and duplex sonography with an intravenous ultrasound contrast agent (Levovist). Results: Eleven patients (9.7%) were converted to open repair; 1 died from hemorrhagic shock secondary to retroperitoneal hematoma. The mean follow-up time was 7.2 months (range 1 to 24), during which 5 patients died of unrelated causes. Sixteen primary (within 30 days) and 5 secondary endoleaks were detected by duplex after tube graft implantation. Among 5 endoleaks due to retrograde side-branch perfusion, 3 were detected only with contrast-enhanced duplex scanning. Iliac artery occlusion was also documented using duplex; however, 2 stent fractures could not be seen with ultrasound. Ten primary endoleaks were detected in bifurcated stent-graft patients. One endoleak originating from the distal iliac limb anchoring site was missed by duplex owing to bowel gas. Graft limb thrombosis was clearly identified by lack of a flow signal on duplex. Conclusions: Duplex sonography could be a valuable, reliable, and economical surveillance tool for endovascular aortic reconstructions. The adjunctive use of an intravenous ultrasound contrast agent increased the sensitivity for detecting endoleak to a level comparable to contrast-enhanced CT scanning. However, stent fractures may not be seen on ultrasound, and bowel gas can interfere with obtaining an adequate image.

Type II Endoleaks:When Is Intervention Indicated and What Is the Index of Suspicion for Types I or III?

“…Diameter measurement is the most commonly used method for determining aneurysm size change, although various methods of diameter measurements have been reported. 9–14 Traditionally, the preferred imaging method for surveillance of EVAR is computed tomographic angiography (CTA), which involves a series of maximal diameter measurements of the aneurysm at regular intervals to determine whether the aneurysm is shrinking, enlarging, or unchanged. Some studies, however, have demonstrated the inaccuracy of diameter measurements, 15–18 noting discrepancies between volume changes and maximal diameter measurements.…”

Color Duplex Ultrasound for the Evaluation of Endovascular Stent Grafts following Endovascular Repair of Abdominal Aortic Aneurysm

“…Endoleak has been identified with all devices implanted to date and occurs in as many as 50% of endovascular repairs. 2–5 There are several types of endoleaks that are categorized by their source (Figure 2). There has been insufficient natural history data to determine the appropriate management of endoleak.…”

“…In experienced hands and with adequate protocols, color duplex ultrasound (CDU) can be used to reliably determine the presence of endoleaks, hemodynamic impairment, and changes in aneurysm size. 8,9…”

Color-Doppler Ultrasonography in the Monitoring of Endovascular Abdominal Aortic Aneurysm Repair

“…In this suspension, the microparticles bind tiny air bubbles, enhancing the Doppler signal quality when injected intravenously by up to 25 dB without increasing background noise. This is a clear improvement in the signal-to-noise ratio (Heilberger et al, 1997). c. Optison (Mallinckrodt, Saint Louis, Missouri): a 1 mL bolus of ultrasound scan contrast agent is given via injection into an antecubital vein, followed by a flush of 5 mL of normal saline solution.…”