michigan hypertension core curriculum - State of Michigan

EPIDEMIOLOGY OF RAS
Fibromuscular dysplasia. FMD is an uncommon disease of unknown etiology, typically occurs in
young females < 30 years of age, and often affects the renal, carotid, and femoral arteries. FMD
should be considered in young patients if severe hypertension is not associated with obesity, oral
contraceptives, or known renal parenchymal disease. Unilateral or bilateral renal FMD may cause
renovascular hypertension, but renal failure/ischemic nephropathy is unusual. The most common form
of renal FMD is medial fibroplasia, characterized by a beaded appearance of the artery in which the
beads are larger than the vessel (Figure 1). Renovascular hypertension due to FMD is readily cured by
balloon angioplasty. 4,5 Renal FMD is characterized by progressive stenosis and occlusion, so patients
should have regular follow-up.
Atherosclerotic renal artery stenosis. ARAS is a common clinical entity, affecting 7% of patients
over age 65 with no known racial predilection, 30% of patients with coronary artery disease, and 60 %
of patients with hypertension, coronary or peripheral artery disease, and renal insufficiency. 6,7 Unlike
FMD, ARAS is not a common cause of renovascular hypertension but is commonly associated with
renal dysfunction. 8 The expectation post-renal stenting, however, should not be cure of hypertension
given that many patients with critical renal artery stenosis had pre-existing essential hypertension.
Accordingly, a more realistic expectation is to reduce the intensity of antihypertensive drug treatment
needed to control BP. Ischemic nephropathy is an important cause of chronic kidney disease and is
the most common cause of end-stage renal failure in elderly patients without diabetes, representing
the primary etiology of end-stage renal disease in 5-16% of patients initiating dialysis each year. 9-13
Ischemic nephropathy leads to progressive renal dysfunction and renal atrophy in 25 % of patients,
despite aggressive antihypertensive therapy 2,9,14,15 Renal artery stenting has supplanted angioplasty
for ARAS 6 , due to better lumen enlargement and less restenosis (Figure 2). 16-21
CLINICAL MANIFESTATIONS OF RAS
Screening for RAS. There are no guidelines for routine screening for RAS. In some patients, the
diagnosis of RAS is made incidentally during angiographic evaluation of lower extremity arterial
diseases, while in others a high index of suspicion is required, based on American College of
Cardiology/American Heart Association (ACC/AHA) guidelines (Table 2, Section 1).
Hypertension Manifestations. Hypertension manifestations include onset of severe hypertension at
age < 30 (FMD) or at age >55 (ARAS), and resistant, accelerated or malignant hypertension. 8,22
NKFM & MDCH 107