Page 303 - Libro 2

18 — Aorta and Iliac Arteries
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Figure 18-10 A: Abnormal spectral waveform associated with hemodynamically significant proximal disease. B: A LEIA spectral waveform within stenosis with a PSV of 346 cm/s.
least a 50% stenosis present. Care should be taken to remain in the artery of interest because elevated velocities in collateral vessels could be mistaken for stenosis. Tortuosity can also cause elevated velocities. In the absence of a stenosis, however, there is usu- ally no poststenotic turbulence associated with the elevated velocity. Chronic iliac occlusions can be diffi- cult to identify. The artery can become contracted and echogenic, and differentiation with the surrounding tissue may be challenging. It is helpful to identify and follow the companion vein when chronic occlusion is suspected (Fig. 18-11A,B).
AORTOILIAC DUPLEX ULTRASOUND FOLLOWING ENDOVASCULAR AORTIC STENT GRAFT REPAIR (EVAR)
The endovascular stent graft repair method of treating AAA has proven to be a much less invasive alterna- tive procedure with lower incidences of periopera- tive mortality and improved survival rate compared
with conventional open surgical repair.15 Recovery from this procedure is considerably shorter than with the traditional method, and there is no abdominal incision.
The endovascular aneurysm method of repair (i.e., EVAR) involves the placement of a stent graft device within the aortic aneurysm sac via a catheter-based delivery system through small groin incisions into the common femoral artery, and deployment is under an- giographic guidance. The goal of this minimally inva- sive treatment is to achieve exclusion of the aneurysm sac from the general circulation, thereby reducing its risk of rupture.16,17 Failure to isolate the aneurysm from the circulation where persistent blood flow is demonstrated outside the graft lumen but within the aneurysm sac has been defined as endoleak and is a common complication associated with many of the commercially available aortic stent graft devices.18–20 Close surveillance, therefore, is mandatory after EVAR, as rupture is still possible if an endoleak is present because the aneurysm continues to be per- fused at near-systemic arterial pressure. This has been
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Figure 18-11 A: Identification of an iliac vein in the presence of an iliac artery occlusion. B: A spectral analysis documents an iliac artery occlusion.