Renovascular hypertension is defined as hypertension resulting from eccentric atheromatous narrowing of renal artery lumen.
Represents 2-5% of hypertensive cases, but is important because it is curable.
Two major causes: atherosclerosis and fibromuscular dysplasias.
Atherosclerosis is the most common cause (60-70%) of renovascular hypertension affecting mainly older individuals.
More common in male.
Has higher incidence in elderly and diabetics.
Atheromatous plaque at origin of renal artery from aorta (involved ~50%).
May show recent thrombosis.
Kidney is small (usually <1/2 normal weight).
Bilateral in ~60% of cases.
Proliferation of smooth muscle (myointimal) cells in arterial intima (image A).
Lipid deposition (cholesterol clefts), histiocytic infiltration (foam cells), necrosis and fibrosis result in narrowing of arterial lumen (image B).
Surgical removal results in cure rate of 60-75% of patients.
With 75% narrowing, ischemic renal disease may occur.