Abstract
Purpose.—
To describe the current Stanford duplex protocol for ultrasound scanning of abdominal aortic aneurysms after endovascular repair. This technique has been used for more than 7 years in the Stanford Vascular Laboratory and has been validated against computed angiography. It. provides quantitative information on aneurysm sac size and flow characteristics, as well as endograft patency and integrity.
Technique.
—Abdominal aortic duplex scans are obtained after the patient has been fasting to minimize bowel gas. An internally standardized duplex scanning protocol is used for assessing the abdominal aorta. The aorta is imaged in gray scale from the diaphragm to the aortic bifurcation to determine the presence of wall defects and to measure the greatest diameter and circumference. Measurements are obtained from the largest segment of the supraceliac aorta, infrarenal aorta, and common iliac arteries. Additional measurements are obtained to document disease of the hypogastric or external iliac artery when not obscured by overlying bowel gas. Circumference measurements using calculation software tools available in most ultrasound equipment are also obtained to more easily monitor the morphologic changes in the aneurysm over time. Color and spectral Doppler are used to evaluate for potential extrastent flow. In addition, velocity waveforms are obtained from each limb to evaluate for changes suggesting potential stenosis from graft compression or outflow obstruction.
Conclusions.
—Duplex ultrasound scanning after endovascular repair of abdominal aortic aneurysms can be used successfully to determine aneurysm size and presence or absence of extrastent flow in 94% of patients. Thus, this technique is applicable to most patients after endovascular repair.
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