Renal artery aneurysms: a 35-year clinical experience with 252 aneurysms in 168 patients

Abstract

Objective: To define the relevance of treating renal artery aneurysms (RAAs) surgically.

Summary background data: Most prior definitions of the clinical, pathologic, and management features of RAAs have evolved from anecdotal reports. Controversy surrounding this clinical entity continues.

Methods: A retrospective review was undertaken of 168 patients (107 women, 61 men) with 252 RAAs encountered over 35 years at the University of Michigan Hospital. Aneurysms were solitary in 115 patients and multiple in 53 patients. Bilateral RAAs occurred in 32 patients. Associated diseases included hypertension (73%), renal artery fibrodysplasia (34%), systemic atherosclerosis (25%), and extrarenal aneurysms (6.5%). Most RAAs were saccular (79%) and noncalcified (63%). The main renal artery bifurcation was the most common site of aneurysms (60%). RAAs were often asymptomatic (55%), with a diagnosis made most often during arteriographic study for suspected renovascular hypertension (42%).

Results: Surgery was performed in 121 patients (average RAA size 1.5 cm), including 14 patients undergoing unilateral repair with contralateral RAA observation. The remaining 47 patients (average RAA size 1.3 cm) were not treated surgically. Operations included aneurysmectomy and angioplastic renal artery closure or segmental renal artery reimplantation, aneurysmectomy and renal artery bypass, and planned nephrectomy for unreconstructable renal arteries or advanced parenchymal disease. Eight patients underwent unplanned nephrectomy, being considered a technical failure of surgical therapy. Dialysis-dependent renal failure occurred in one patient. There were no perioperative deaths. Late follow-up (average 91 months) was available in 145 patients (86%). All but two arterial reconstructions remained clinically patent. Secondary renal artery procedures included percutaneous angioplasty, branch embolization, graft thrombectomy, and repeat bypass for late aneurysmal change of a vein conduit. Among 40 patients with clearly documented preoperative and postoperative blood pressure measurements, 60% had a significant decline in blood pressure after surgery while taking fewer antihypertensive medications. Late RAA rupture did not occur in the nonoperative patients, but no lessening of this group's hypertension was noted.

Conclusion: Surgical therapy of RAAs in properly selected patients provides excellent long-term clinical outcomes and is often associated with decreased blood pressure.

Figure 1. Location of renal artery aneurysms (RAAs) in each segmental division. Most RAAs occur at the main renal artery bifurcation.

Figure 2. Clinical course of renal artery aneurysms encountered at the University of Michigan Hospital, 1965 to 2000.

Figure 3. Aneurysmectomy and primary angioplastic closure of the renal artery. (A) Preoperative distal subtraction angiography image of a 3.0-cm renal artery aneurysm. (B) Postoperative digital subtraction angiography image showing the normal-appearing bifurcation without evidence of stenosis.

Figure 4. Renal aneurysmectomy and reimplantation of lower pole renal artery, with aneurysmectomy and angioplastic closure of upper pole renal artery. (A) Preoperative digital subtraction angiography demonstration of segment 5 and 6 renal artery aneurysms. (B) Postoperative digital subtraction angiography appearance of reimplanted lower pole artery without stenosis and normal-appearing upper pole segmental bifurcation (arrows).

Figure 5. Renal artery aneurysm excision and bypass in a patient with fibrodysplasia of the renal artery. (A) Preoperative arteriogram documenting saccular aneurysm at the main renal artery bifurcation, with irregularities of medial fibrodysplasia evident in the proximal renal artery. (B) Postoperative image of saphenous vein bypass, with end-to-end anastomosis of the upper pole artery and end-to-side implantation of the lower pole (arrows).

Figure 6. An unreconstructable renal artery with a complex ruptured renal artery aneurysm. A primary nephrectomy was performed with an excellent outcome. (A) Arterial phase digital subtraction angiography image of a large ruptured inferior pole renal artery aneurysm communicating with an adjacent vein. (B) Venous phase exhibiting rapid filling of the inferior vena cava with contrast.

Figure 7. Life table of event-free survival in patients undergoing surgical therapy. Small dashed line represents renal artery aneurysm exclusion and bypass. Solid line represents angioplastic closure and segmental artery reimplantation. Long dashed line represents nephrectomy. No significant difference was noted between these modes of therapy in long-term event-free outcome. Beyond 250 months, only nine patients had follow-up among all groups, and comparison is not valid.