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