Renal artery stenosis: if and when to intervene

Abstract

Purpose of review: Atherosclerotic renovascular disease remains highly prevalent and presents an array of clinical syndromes. Recent prospective trials have dampened enthusiasm for revascularization generally, but clinicians recognize the need to identify patients likely to benefit from vascular intervention.

Recent findings: This article highlights the inflammatory nature of vascular occlusive disease and the limits of the kidney to adapt to reduced blood flow. Although moderate reductions can be tolerated, severe impairment of renal perfusion leads to tissue hypoxia and activates inflammatory injury within the kidney. Hence, assessment of kidney viability and potential tools to modify mitochondrial and inflammatory damage may be important to identify patients for whom clinical intervention should be undertaken.

Summary: Clinicians must recognize clinical syndromes that identify 'high-risk' groups and apply revascularization in those likely to benefit. Future efforts to protect the kidney (e.g., mitochondrial protection) or cell-based therapy may amplify clinical recovery when combined with restoring renal blood flow.

Figure 1

Spectrum of atherosclerotic renovascular disease: Clinical manifestations vary considerably depending in part on the severity of vascular occlusion, but also the state of the underlying kidney (see text). While many lesions are of minor hemodynamic importance, prolonged and severe vascular occlusion accelerates hypertension, circulatory congestion and ultimately threatens viability of the kidney (figure from (3) with permission)

Figure 2

Tissue oxygenation and renal blood flow: Because the kidney is abundantly perfused in its function as a filtering organ, it can tolerate moderate reductions in blood flow without developing overt tissue hypoxia. Beyond a critical threshold, however, further reductions lead to tissue hypoxia and activation of oxidative stress and tissue inflammatory injury within the kidney. The clinical effects following renal artery revascularization depend upon the underlying state of the kidney. Many of the prospective RCTs have been hampered by recruitment of relatively minor renovascular disease as compared to observational studies of more severe clinical syndromes. (Figure from reference , with permission)

Figure 3

(A) Serum creatinine, blood pressure and medications over an eight year period in a patient with unilateral atherosclerotic renovascular disease associated with a nonfunctioning kidney (less than 5% by renal scan). This patient developed severe hypertension that responded well to a regiment based upon an angiotensin receptor blocker (valsartan). Several years later, however, she developed worsening renal failure with an eGFR = 16 ml/min/1.73m2, leading to evaluation for kidney transplantation. Her disease was managed conservatively, but she developed severe hypertension and worsening renal function (creatinine above 5.0 mg/dL), leading her physician to withhold the ARB. Serum creatinine fell, although blood pressure was difficult to control and she developed episodes of acute pulmonary edema. (B) Doppler ultrasound identified a stenosis to her remaining functional kidney (peak systolic velocity above 500 cm/s). This was treated with endovascular stenting, with marked improvement in blood pressure levels, stable kidney function and tolerance to restarting the ARB (valsartan).

Figure 3

(A) Serum creatinine, blood pressure and medications over an eight year period in a patient with unilateral atherosclerotic renovascular disease associated with a nonfunctioning kidney (less than 5% by renal scan). This patient developed severe hypertension that responded well to a regiment based upon an angiotensin receptor blocker (valsartan). Several years later, however, she developed worsening renal failure with an eGFR = 16 ml/min/1.73m2, leading to evaluation for kidney transplantation. Her disease was managed conservatively, but she developed severe hypertension and worsening renal function (creatinine above 5.0 mg/dL), leading her physician to withhold the ARB. Serum creatinine fell, although blood pressure was difficult to control and she developed episodes of acute pulmonary edema. (B) Doppler ultrasound identified a stenosis to her remaining functional kidney (peak systolic velocity above 500 cm/s). This was treated with endovascular stenting, with marked improvement in blood pressure levels, stable kidney function and tolerance to restarting the ARB (valsartan).