Page 3 - Carotid and peripheral vascular interventions textbook
P. 3


                 between the suprarenal aorta and the iliac artery. However,   the stenotic kidney. With prolonged exposure, there is
                 in some instances, the accessory renal artery can have     progression of arteriosclerotic lesions and parenchymal
                 a caliber similar to the main renal artery (Fig. 10-1C),   injury to the contralateral kidney that may lead to persistent
                 thus providing a large part of the renal blood supply.     proteinuria and result in pathologic changes from secondary
                 In this circumstance revascularization of the accessory   focal segmental glomerulosclerosis of the contralateral
                 renal artery stenoses should be performed. Normally,    kidney. Revascularization in patients with severe unilateral
                 a main renal artery remains intact for several centimeters   renal artery stenosis may prevent atrophy of the affected
                 prior to dividing into a variable number of segmental   kidney and protect the contralateral kidney.
                 branches. Early subdivision or bifurcation of the main      About 20% of patients have a single functioning
                 renal artery (Fig. 10-1D) is the second most common   solitary kidney or bilateral RAS disease. These worse
                 anatomic variant, and it makes optimal percutaneous   case scenarios create a state of sodium and f uid retention
                 revascularization more challenging.             so that volume-dependent hypertension develops which
                                                                 then aggravates heart failure symptoms in patients
                 PATHOPHYSIOLOGY                                 who have impaired left ventricular function and causes

                                                                 progressive worsening of renal function. These subgroups
                     Signif cant ARAS is generally a luminal stenosis   of ARAS are two of the few absolute indications for
                 >70% that leads to reduced renal perfusion pressure   endovascular revascularization.
                 and stimulates the renin-angiotensin-aldosterone system
                 (RAAS) (Fig. 10-2) (15). The net effect of this activation  ETIOLOGY

                 results in sodium retention, peripheral vasoconstriction,
                 aldosterone secretion, vascular remodeling, inf ammation      Renal artery stenosis has many etiologies (Table 10-1).
                 and triggering of additional vasopressor mechanisms   The most common is atherosclerosis that is progression
                 including endothelin and sympatho-adrenergic pathways   of  aortic  atherosclerotic  plaque  which  affects  the
                 (16,17).                                        proximal segments of the renal arteries and the renal
                     ARAS  has  two  principle  pathophysiological    ostia (Fig. 10-3A).
                 consequences: 1) RAAS activation (in unilateral stenosis)        Fibromuscular dysplasia (FMD) is the 2  most frequent
                 and 2) reduced glomerular f ltration and water and salt   etiology and is a nonatherosclerotic, noninf ammatory
                 excretion (i.e., bilateral artery stenosis or Pickering    disorder with unknown etiology that typically affects
                 syndrome (18) or renal artery stenosis of a solitary kidney).   women aged between 15-50 years (19). FMD commonly   251
                 Although the post-stenotic kidney has less perfusion, the   involves on the mid to distal portions of the renal arteries
                 contralateral kidney experiences glomerular hyperf ltration   and causes the angiographic appearance of “string of
                 and hyperperfusion associated with RAAS activation by   beads” aneurysmal appearance (Fig. 10-3B). Contrasting

                 A                      B                       C                      D

                 Figure 10-1. Anatomical variations of renal artery. A: Normal single renal artery. B: An accessory inferior pole renal artery. C: Two main
                 renal artery. D: Early bifurcation of renal artery. (Redrawn with permission from Omar R, Kisansa M, Dehnavi AD. The prevalence of anatomical
                 variants of the coeliac trunk and renal arteries on contrast-enhanced abdominal computed tomography scans at Dr George Mukhari Academic
                 Hospital. SA J Radiol. 2021;25:1990.)
   1   2   3   4   5   6   7   8