Noninvasive Color Doppler Inspection of Small‐Diameter Vascular Grafts Implanted in Canine Carotid and Femoral Arteries

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Abstract
To noninvasively evaluate a small-diameter vascular graft (approx. 4 mm in diameter) developed for coronary artery bypass application, a state-of-the-art color Doppler flow mapping system was applied to inspect various grafts implanted in 5 canines. The grafts, including Denaflex, Gore-Tex ePTFE, and Bioflow, were implanted interpositionally in the carotid and femoral arteries. Inspections were conducted with a 5 MHz linear vascular transducer at 6 weeks postimplantation and 12 weeks postimplantation, immediately prior to retrieval. In the carotid artery position, all 5 Denaflex grafts were patent throughout the implantation period while 2 of the 5 Gore-Tex grafts were occluded at 6 weeks, and 1 more was occluded at 12 weeks. In the femoral artery position, all 5 Denaflex grafts were patent at 6 weeks; however 2 were occluded at 12 weeks. For the Bioflow grafts at 6 weeks, 3 were patent, and 2 were occluded. The same results were observed at 12 weeks. The color Doppler inspection results indicated a higher patency rate in the carotid artery position than in the femoral artery position. Furthermore, the volumetric flow rate and the wall shear stress measured with the pulsed Doppler in the carotid artery were greater than in the femoral artery. These findings suggest that the hemodynamic "environment" in which the graft was implanted may affect the graft patency rate. The Doppler inspection results obtained at 12 weeks, identical with those observed after retrieval, demonstrated that color Doppler flow mapping is a reliable method to noninvasively inspect blood flow through small-diameter vascular grafts.