Brief history: 52-year-old female with uncontrolled hypertension.
Salient findings: The middle third of the arteries are involved with a “string of pearls” appearance of alternating webs and stenoses. This appearance is classic for fibromuscular dysplasia (FMD) (white arrow, above). The patient also has a 1.8-cm right renal artery aneurysm at the trifurcation of her first order renal artery branches (black arrow, above).
Figure 1. 3D CT angiogram.
Patient population and natural history of disease: FMD is most common in young adult females, and its etiology is unknown. An association with alpha-1 antitrypsin deficiency has been reported in the literature. FMD is a leading cause of curable hypertension. Clinical manifestations of FMD include distal embolization of thrombus formed in small aneurysms, hypertension/ischemia due to obstruction by webs, and occlusion/infarct via spontaneous dissection. The natural prevalence of renal artery aneurysms is low—0.1% in all angiography patients—and its natural course is not well established. Renal artery aneurysms are most common in FMD, vasculitides, neoplasm, trauma, and Ehlers-Danlos Syndrome; they may be iatrogenic or idiopathic.
Management: Symptomatic medial fibroplasia-type FMD responds well to balloon angioplasty. Renal artery aneurysms may be managed medically or surgically, depending on risk factors. Indications for repair of renal artery aneurysms include a size of 2 cm or greater, pregnancy, expansion, renovascular hypertension, distal embolization, and rupture. Mortality from ruptured renal artery aneurysms is 10% in nonpregnant patients and 55% during pregnancy.
This patient had a good response to balloon angioplasty of the left renal artery. The right renal artery could not be angioplastied secondary to increased risk of aneurysm rupture with restoration of arterial blood flow due to increased pressure on the walls of the aneurysm. Hence, physicians surgically resected the right renal artery aneurysm and performed a bypass to the aorta.
Figure 2. Intraoperative photograph of renal artery aneurysm.
Take Home Points
- FMD is most common in young or middle-age women;
- FMD is a type of curable hypertension, treated by renal artery angioplasty;
- FMD is diagnosed by an angiographic study—in classic cases, the involved artery has a string of pearls appearance; and
- FMD is associated with renal artery aneurysms. Consider surgical intervention in aneurysms greater than 2 cm. TH
Helena Summers is a radiology resident and Erik Summers is a hospitalist at the Mayo Clinic College of Medicine, Rochester, Minn.
Bibliography
- Kaufman JA, Lee MJ. Vascular and Interventional Radiology: The Requisites. Philadelphia: Mosby; 2004.
- Bisschops RH, Popma JJ, Meyerovitz MF. Treatment of fibromuscular dysplasia and renal artery aneurysm with use of a stent-graft. J Vasc Interv Radiol. 2001 Jun;12(6):757-760.
- Luscher TF, Lie JT, Stanson AW, et al. Arterial fibromuscular dysplasia. Mayo Clin Proc. 1987;62:931-952.