Open and Endovascular Repair of Abdominal Aortic Aneurysms in Kidney Transplant Patients



Open and Endovascular Repair of Abdominal Aortic Aneurysms in Kidney Transplant Patients



Adam H. Power and Peter Gloviczki


Aortic reconstructions for an abdominal aortic aneurysm (AAA) in kidney transplant recipients have been increasing steadily since the 1990s for a variety of reasons: These patients often have accelerated atherosclerosis caused by hemodialysis and other cardiovascular risk factors; renal transplantation has been extended to older and more high-risk patients in whom an AAA is more likely; and AAAs tend to grow faster in patients who receive transplant immunosuppressive therapy. Treatment of an AAA in patients with a transplanted kidney creates a dilemma as to when the AAA requires repair and how to preserve the kidney’s perfusion and function during open or endovascular aortic reconstruction.




Renal Protection


Preoperative Measures


General principles of preoperative assessment apply with a focus on optimizing renal function before AAA repair. Aortoiliac imaging must be pursued cautiously, knowing that patients with compromised kidney function will be at increased risk for contrast-induced nephropathy. Patients with transplanted kidney and normal kidney function are usually able to tolerate iodinated contrast for arteriographic studies or computed tomography (CT) scans (Figure 1). Patients with suboptimal kidney function might require other means of contrast imaging. Magnetic resonance angiography (MRA) using gadolinium once was thought to be safer than standard iodinated contrast agents. However, several reports on nephrogenic systemic fibrosis have tempered enthusiasm for this agent.


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FIGURE 1 A, Three-dimensional reconstruction of preoperative computed tomography (CT) scan shows infrarenal abdominal aortic aneurysm (AAA) and transplanted kidney in right pelvis. B, Coronal CT scan shows infrarenal AAA and right common iliac aneurysm with normal transplanted kidney. (From Ailawadi G, Bedi A, Williams DM, et al: Endovascular treatment of aortic aneurysms in patients with renal transplants, J Vasc Surg 37:693–696, 2003.)

Other potentially useful radiographic imaging techniques for protecting the kidneys include carbon dioxide angiography, intravascular ultrasound, and direct aortic catheter placement before CTA to limit contrast dosage. Sodium bicarbonate intravenous infusion and N-acetylcysteine (Mucomyst) given periprocedurally may be of some benefit, although level I evidence for using these agents is lacking. Regardless, hydration, either oral or intravenous, is paramount, and medications affecting kidney function, such as metformin, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers, diuretics, nonsteroidal antiinflammatory drugs (NSAIDs), and cyclooxygenase-2 (COX-2) inhibitors, should be held before contrast is administered.



Intraoperative Techniques


The need for protection of the transplanted kidney during AAA repair differentiates these patients from those requiring standard open or endovascular aortic reconstructions. The single artery supply and lack of collaterals make these renal allografts more susceptible to ischemic injury than native kidneys.


In open repair, aortic clamping results in decreased perfusion of the transplanted kidney, limited to flow originating from the lumbar, inferior mesenteric, and external iliac arteries. Intraoperative adjunctive renal protection measures can be done selectively, required only in patients with longer than 30 to 60 minutes of warm ischemia. However, some advocate renal protection in all patients, especially in those with impaired kidney function. Techniques of renal protection include a temporary shunt from the aorta to the iliac or femoral artery, temporary subclavian or axillofemoral shunt or bypass, in situ renal perfusion with a pump oxygenator by way of cannulation of the femoral vessels, in situ renal perfusion with cold solution through the common iliac artery, topical cooling, and general hypothermia. Even though shunting provides the kidney graft with steady blood perfusion, there is a risk of thromboembolization when cannulating atherosclerotic arteries, especially the proximal aorta. Furthermore, extracorporeal circulation increases the risk of hemorrhage and coagulopathy. Thus, selective hypothermia of the transplant by in situ perfusion with cold (4°C) Ringer’s lactate through the common iliac artery combined with topical cooling seems preferable (Figure 2). Explantation with temporary perfusion of the kidney followed by reimplantation has also been described, but it is complex and rarely required.


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FIGURE 2 Perfusion cooling through the recipient iliac artery for kidney transplant protection. (From Panneton JM, Gloviczki P, Canton LG, et al: Aortic reconstruction in kidney transplant recipients, Ann Vasc Surg 10:97–108, 1996.)

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  2. In-Situ Treatment of Aortic Graft Infection with Prosthetic Grafts and Allografts
  3. Treatment of Acute Upper Extremity Venous Occlusion
  4. Intraoperative Assessment of the Technical Adequacy of Carotid Endarterectomy

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Aug 25, 2016 | Posted by in CARDIOLOGY | Comments Off on Open and Endovascular Repair of Abdominal Aortic Aneurysms in Kidney Transplant Patients

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