Renal Artery Stenosis
Should patients with a solitary kidney undergo surgery or stenting?
Primary care physicians are now recognizing renal artery disease with greater frequency. If left untreated, renovascular disease can lead to resistant hypertension or renal failure requiring dialysis. The decreased morbidity and mortality of percutaneous interventions has further increased awareness of this problem. As a result, patients are now commonly referred to interventionalists for treatment of a symptomatic renal artery stenosis, particularly when significant comorbidities increase the risk of surgical revascularization. Patients who harbor renovascular disease within a solitary functioning kidney represent an especially challenging category of patients seen by interventionalists. This article provides a brief overview of the risks and benefits of surgical and percutaneous treatment options for atherosclerotic renovascular disease in a solitary kidney.
The surgical approach to renal artery disease dates back to 1954, when Freeman reported the resolution of hypertension in a patient who underwent a bilateral renal artery endarterectomy.1 Today, traditional surgical revascularization for a renal artery stenosis can be performed by several techniques, including endarterectomy and renal artery bypass.
Endarterectomy is a technique of revascularization that is currently not as commonly used by vascular surgeons as renal artery bypass. Endarterectomy requires complete cross-clamping of the aorta, which is not well tolerated by patients with significant cardiac and renal disease. This technique is more frequently used when additional aortic reconstruction is necessary, such as in aneurysmal disease.
Most surgeons prefer to perform a renal artery bypass using the aorta as the source of inflow, but other options for inflow exist. Patients who are too ill to tolerate an aortic clamp may have a splenorenal or hepatorenal bypass for left-sided and right-sided renal artery stenoses, respectively (Figures 1 and 2). Both autologous and prosthetic conduits can be used; long-term data support the durability of either choice. A notable exception, however, is the pediatric patient in which the hypogastric artery would be a preferred conduit due to the high incidence of aneurysmal degeneration in pediatric vein grafts and size limitations of prosthetic conduits in the growing child.
The goal of surgical reconstruction is to effectively revascularize the affected kidney while minimizing the warm ischemic time. It is possible to selectively perfuse an ischemic kidney during surgery, but this is usually unnecessary. A technically appropriate anastomosis can be performed with 10 to 12 minutes of warm renal ischemia, which would not likely exacerbate pre-existing renal insufficiency. If desired, the reconstruction can be interrogated intraoperatively by Duplex examination, thereby confirming the absence of any technical problems that might compromise the graft patency.
Factors that favor surgical revascularization over angioplasty/stenting in patients with a solitary functioning kidney include the potential risk of kidney loss and limited long-term data regarding the durability of percutaneous interventions. The estimated risk of renal loss from dissection, thrombosis, or perforation during a percutaneous intervention has been as high as 4% to 6% in some studies, whereas loss of a kidney secondary to an acutely thrombosed bypass graft is less than 2% in most surgical series.2 Some practitioners still question the long-term durability of percutaneous interventions. This is not as much the case with surgical revascularization. A study by Oertle revealed a restenosis rate of 64% in patients treated by a percutaneous technique.3 The increased use of stents in the management of a renal artery stenosis has decreased this complication.
The efficacy of percutaneous treatment of renal artery stenosis has been well described in the literature, including a recent review in this publication.4 The focus of this section is on the growing evidence in the literature for the safety and efficacy of this modality for treating patients with renal artery stenosis and a solitary functioning kidney.
Several recent studies have highlighted the utility of renal artery angioplasty/stenting in this population (Table 1). Shannon et al reported a 100% initial technical success rate with angioplasty and the use of a Palmaz stent (Cordis Endovascular, a Johnson & Johnson company, Miami, FL) in 21 patients with a solitary kidney.5 Seventy-one percent of patients experienced improvedt or stabilized renal function. All four patients that were previously undergoing dialysis were able to discontinue the treatment. There was a 19% major complication rate, with one death.
Cioni et al used a similar technique in 16 patients.6 Again, initial technical success was reported at 100%. Primary patency at 24 months was 75%. Although renal function improved or stabilized in more than 80% of the patients, the investigators were unable to demonstrate a significant decrease in postprocedural creatinine values.
Chatziioannou et al recently reported on 26 patients with a solitary kidney treated by renal artery angioplasty/stenting.7 The investigators based their clinical efficacy on stabilization or reduction of the creatinine value by 20%. With these guidelines, the investigators reported a 62% response rate to treatment. They concluded that patients with less-progressed renal insufficiency responded better to a percutaneous intervention when creatinine levels were assessed.
Our group at Emory reported on 27 patients with a solitary kidney who underwent renal artery angioplasty/stenting.8 Reported experience covered a 7-year period. The response to treatment based on serum creatinine values was good (defined by stable or improving creatinine) in 74% of patients. Although there was an improvement in hypertension parameters, the number of antihypertensive medications was unchanged. One patient required urgent renal bypass for a dissected renal artery. There was one death in the series of a patient who was anuric after a contralateral nephrectomy and underwent thrombolytic treatment. The patient died from a cerebral hemorrhage. The overall complication rate was 22%. This value compares favorably to the results of Reilly’s surgical series with a 43% complication rate.9
PROVIDE INDIVIDUALIZED CARE
Although both surgical and percutaneous approaches have risks and benefits, it is important to individualize treatment for a given patient. A discussion of each approach is necessary prior to defining the treatment plan. Growing evidence in the literature states that percutaneous management of a renal artery stenosis in patients with a solitary kidney can be safely performed. The complication rates are comparable or less than those seen with traditional surgical approaches. Deciding which patients will benefit most from treatment is still undefined. Further work is necessary to identify the patients who will best respond to treatment to reduce their hypertension or halt the progression of renal failure leading to dialysis. In the meantime, the combination of angioplasty and stenting will continue to grow in its application to this challenging subset of patients. We will continue to pursue a percutaneous approach when confronted with patients with atherosclerotic renal disease and a solitary kidney.
Ross Milner, MD, is Assistant Professor in the Division of Vascular Surgery at Emory University School of Medicine in Atlanta, Georgia. Dr. Milner may be reached at (404) 778-5451; email@example.com.
Elliot L. Chaikof, MD, PhD, is the John E. Skandalakis Professor of Surgery and Chief of the Division of Vascular Surgery at Emory University School of Medicine in Atlanta, Georgia. Dr. Chaikof may be reached at (404) 727-8413; firstname.lastname@example.org.
1. Freeman NE, Leeds FH, Elliot WG, et al. Thromboendarterectomy for hypertension due to renal artery occlusion. JAMA. 1954;156:1077.
2. Paty PS, Darling RC III, Lee D, et al. Is prosthetic renal artery bypass reconstruction a durable procedure? An analysis of 489 bypass grafts. J Vasc Surg. 2001;34:127-132.
3. Oertle M, Do DD, Baumgartner I, et al. Discrepancy of clinical and angiographic results in the follow-up of percutaneous transluminal angioplasty (PTRA). Vasa. 1998;27:154-157.
4. Spinosa DJ and Rosenfeld K. Renal artery stenosis and renal insufficiency. Endovasc Today. 2002;2:17-20.
5. Shannon HM, Gillespie IN, Moss JG. Salvage of the solitary kidney by insertion of a renal artery stent. Am J Roentgenol. 1998;171:217-222.
6. Cioni R, Vignali C, Petruzzi P, et al. Renal artery stenting in patients with a solitary functioning kidney. Cardiovasc Intervent Radiol. 2001;24:372-377.
7. Chatziioannou A, Mourikis D, Agroyannis B, et al. Renal artery stenting for renal insufficiency in solitary kidney in 26 patients. Eur J Vasc Endovasc Surg. 2002;23:49-54.
8. Bush RL, Martin LG, Lin PH, et al. Endovascular revascularization of renal artery stenosis in the solitary functioning kidney. Ann Vasc Surg. 2001;15:60–66.
9. Reilly JM, Rubin BG, Thompson RW, et al. Revascularization of the solitary kidney: A challenging problem in a high-risk population. Surgery. 1996;120:732-736.