Page 2 - Carotid and peripheral vascular interventions textbook
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                    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
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