With a Little Help From My Friends: the Role of the Renal Collateral Circulation in Atherosclerotic Renovascular Disease

Abstract

The collateral circulation can adapt to bypass major arteries with limited flow and serves a crucial protective role in coronary, cerebral, and peripheral arterial disease. Emerging evidence indicates that the renal collateral circulation can similarly adapt and thereby limit kidney ischemia in atherosclerotic renovascular disease. These adaptations predominantly include recruitment of preexisting microvessels for arteriogenesis, with de novo vessel formation playing a limited role. Yet, adaptations of the renal collateral circulation in renovascular disease are often insufficient to fully compensate for the limited flow within an obstructed renal artery and may be hampered by the severity of obstruction or patient comorbidities. Experimental strategies have attempted to circumvent limitations of collateral formation and improve the prognosis of patients with various ischemic vascular territories. These have included pharmacological approaches such as endothelial growth factors, renin-angiotensin-aldosterone system blockade, and If-channel-blockers, as well as interventions like preconditioning, exercise, enhanced external counter-pulsation, and low-energy shock-wave therapy. However, few of these strategies have been implemented in atherosclerotic renovascular disease. This review summarizes current understanding regarding the development of renal collateral circulation in atherosclerotic renovascular disease. Studies are needed to apply lessons learned in other vascular beds in the setting of atherosclerotic renovascular disease to develop new treatment regimens for this patient group.

Endovascular Versus Medical Management of Atherosclerotic Renovascular Disease: Update and Emerging Concepts

“…40 Indeed, it should be considered that patients with only moderate RAS may suffer from essential hypertension, rather than from true renovascular hypertension, that is a form of hypertension fully reversible after PTRA. This is also true if considering chronic kidney ischemia amelioration due to renal collateral revascularization, 41 based on the remodeling of preexistent microvessels through arteriogenesis, 42,43 which has been demonstrated to preserve kidney function in mild-to-moderate RAS. 44 Therefore, although we may question whether moderate-degree RAS do benefit from blood flow restoration, the effectiveness of PTRA on high-degree stenosis remains mostly unexplored since patients with such lesions were a small minority, or even excluded from major trials according to study protocol.…”