Page 2 - Carotid and peripheral vascular interventions textbook
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CHAPTER 1 0
CAROTID AND PERIPHERAL VASCULAR INTERVENTIONS: STEP-BY-STEP
Renal artery intervention
Thosaphol Limpijankit
INTRODUCTION failure that is unresponsive to a combination therapy
medication and (2) to stabilize or improve renal function.
Atherosclerotic renal artery stenosis (ARAS) is Renal revascularization using percutaneous transluminal
one of the common etiologies of secondary hypertension renal artery stenting (PTRAS) in selected groups of
and is associated with resistant ischemic nephropathy, population with severe ARAS has proven to be benef t
hypertension, and cardiac destabilization (1). This disorder (9,10) even though several randomized-controlled trials
remains underrecognized and undertreated because failed to demonstrate the superiority of PTRAS versus
most patients have no symptoms or signs. Several studies optimal medical therapy (OMT) (11-13).
examining the natural history of ARAS have shown that,
without intervention, progressive vascular occlusion ANATOMIC CONSIDERATIONS
commonly occurs with worsening severity of stenosis
by 50% at 5 years (2-4). If undiagnosed, ARAS usually The two renal arteries arise from the lateral surface
leads to renal function deterioration and progressive renal of the descending aorta at around the L1-L2 vertebral
atrophy and causes 12-14% of dialysis-dependent renal level, just below to the anterior origin of the superior
failures (5). mesenteric artery. The origin of the right renal artery is
The diagnosis and early treatment of ARAS as frequently slightly higher than the left renal artery, the
a potentially correctable etiology of hypertension and take-off points are slightly posterior, and the main renal
renal insuff ciency, has increased using non-invasive artery remains intact for a variable length (Fig. 10-1A).
imaging modalities such as doppler ultrasound study The proximal renal arteries have small inferior adrenal,
250 (DUS), magnetic resonance angiography (MRA), and ureteric and capsular branches, that are usually not visible
computerized tomography angiography (CTA). Although during arteriography. At the renal hilum, the renal artery
the incidence of ARAS recognized by DUS within bifurcates into ventral and dorsal rami. These trunks branch
a general population ranges between 0.5% and 7% (6), into segmental arteries, lobar arteries, interlobar, arcuate,
the prevalence increases to 14-39% in patients receiving and interlobar arteries. Within the renal cortex, the arcuate
coronary angiography (7) and 14-42% in patients undergoing and interlobular arteries branch into the smaller afferent
peripheral artery angiography (8). The higher prevalence arterioles which penetrate the renal cortex and medulla to
rates in these high-risk populations emphasize using supply the glomeruli. Importantly, in these small vessels
a screening test to diagnose underlying asymptomatic atherosclerotic disease on top of hypertensive glomerular
renal artery stenosis. injury can explain deterioration of renal function and
Although ARAS-associated hypertension may incurable hypertension, even following successful renal
be successfully managed with medication, but it has artery revascularization.
a propensity to be more resistance than primary essential There are a number of differences in renal artery
hypertension, often requiring more medication. In addition, anatomy. The most frequent variation is the presence of
patients are more likely to suffer from shortened life span one or more accessory renal arteries that are identif ed
and progressive renal failure than those treated with renal during angiography in about 25% to 35% of cases (14).
artery revascularization. Most accessory renal arteries are usually small caliber
The aims of renal artery revascularization are (1) and typically supply the lower pole (Fig. 10-1B) or the
to improve or cure renovascular hypertension or heart upper pole of the kidney which may arise anywhere