Transplant Artery Stenosis

Cadaveric transplant kidneys are joined to the recipient's external iliac artery via an end-to-side anastamosis. Living donor kidneys are joined to either the external iliac

Figure 14 Contrast-enhanced MR angiogram showing bilateral severe RAS (arrows). Note the post-stenotic dilatation. Abbreviations: MR, magnetic resonance; RAS, renal artery stenosis. Source: Courtesy of Joe Brookes, The Middlesex Hospital, London.
String Pearls Fmd Images
Figure 15 Contrast-enhanced MR angiogram showing the ''string of pearls'' (arrow) appearance of FMD in the right renal artery. Abbreviations: FMD, fibromuscular dysplasia; MR, magnetic resonance. Source: Courtesy of Joe Brookes, The Middlesex Hospital, London.

end-to-side or internal iliac end-to-end (109). Stenosis of the transplant artery is well recognized. Improved surgical techniques and immunosuppressive therapy have led to increased graft longevity. As a result, transplant artery stenosis is more of a clinical problem with an incidence of 1% to 15% (110,111), mostly within the first three years. Stenosis can occur in the recipient iliac artery, at the anastamosis, or distal to the anastamosis. Causes and predisposing factors include native vessel atherosclerosis, clamp injury, rejection, turbulence distal to the anastamosis, and surgical technique (109). Clinical pointers to stenosis include hypertension and worsening function in the absence of rejection or ureteric obstruction.

As with native renal arteries, a variety of noninvasive tests have been investigated to exclude stenosis. Contrast-enhanced MRA shows promise with sensitivities and specificities of up to 100% and 97% respectively (112). As before, its avoidance of radiation and nephrotoxic agents are particular strengths and its tendency to overgrade stenosis, a weakness. CTA should also provide an accurate assessment of the transplant artery but requires a large volume of contrast, and metallic surgical clips may cause streak artifact. Duplex ultrasound is the most commonly used screening method, with sensitivities of 87% to 94% and specificities of 86% to 100% (113-115) in experienced hands. Of the multiple Doppler indices, peak systolic velocity has been shown to be the most accurate (111). A peak systolic velocity of greater than 2.5 m/sec was 100% sensitive and 95% specific for the detection of stenosis greater than 50%. In our more recent experience, this threshold performs poorly in a low-risk or surveillance population (116), so we now use a threshold of 3.0m/sec. However, vessel tortuosity can make scanning problematic, and inadequate angle correction may reap misleading results. Catheter angiography with pressure measurement may still be needed to exclude stenosis or differentiate it from vessel kinking (117). An ipsilateral approach is used if the transplant is joined end-to-side to the external iliac artery (Fig. 16A). End-to-end internal iliac anastamoses are easier to catheterize from the other side. Rotational angiography (118) with 3-D

Figure 16 (A) Transplant angiogram, RAO 60 projection. The transplant artery is joined end-to-side to the external iliac artery. There is a significant proximal stenosis (arrow). (B) Carbon dioxide run at the same projection. Note the poor delineation of the peripheral vessels. (C) Gadolinium angiogram taken postdeployment of a 6 mm stent. Although the opacification is not as good as conventional contrast, the renal artery branches are well seen. Abbreviation: RAO, right anterior oblique.

Figure 16 (A) Transplant angiogram, RAO 60 projection. The transplant artery is joined end-to-side to the external iliac artery. There is a significant proximal stenosis (arrow). (B) Carbon dioxide run at the same projection. Note the poor delineation of the peripheral vessels. (C) Gadolinium angiogram taken postdeployment of a 6 mm stent. Although the opacification is not as good as conventional contrast, the renal artery branches are well seen. Abbreviation: RAO, right anterior oblique.

reconstruction, or at least multiple projections, should be used to demonstrate the artery to advantage. The use of contrast agents carbon dioxide and gadolinium is limited by bolus fragmentation and poor visibility, respectively (Fig. 16B,C). As in the native renal artery, a pressure gradient should always be sought before intervention is performed.

Was this article helpful?

0 0
Reducing Blood Pressure Naturally

Reducing Blood Pressure Naturally

Do You Suffer From High Blood Pressure? Do You Feel Like This Silent Killer Might Be Stalking You? Have you been diagnosed or pre-hypertension and hypertension? Then JOIN THE CROWD Nearly 1 in 3 adults in the United States suffer from High Blood Pressure and only 1 in 3 adults are actually aware that they have it.

Get My Free Ebook


Post a comment