Diagnosis and Management of Renal Artery Stenosis

Initial Clinical Assessment

The American College of Radiology suggests looking for abdominal bruit on physical examination as a clinical indicator that raises suspicion for renal artery stenosis, particularly in patients with severe hypertension, age-related patterns, or treatment resistance 3, 1
The European Society of Cardiology recommends considering age-related patterns, such as severe hypertension in patients <35 years old or new-onset hypertension after age 50, as well as treatment resistance, as indicators for renal artery stenosis 3, 1
Medication-induced renal deterioration, such as worsening renal function after starting ACE inhibitors or ARBs, should also be considered as a potential indicator for renal artery stenosis 3, 1
Flash pulmonary edema, particularly suggesting bilateral disease, is a key clinical clue for renal artery stenosis 1
Generalized atherosclerotic disease with concurrent hypertension is also a relevant clinical indicator 3

The European Society of Cardiology gives a Class I, Level B recommendation for using Duplex Doppler ultrasound as the initial imaging modality, with a primary criterion of PSV ≥200 cm/s indicating ≥60% stenosis with sensitivity 73-91% and specificity 75-96% 1, 2
Secondary supportive criteria to improve accuracy include renal-aortic ratio (RAR) ≥3.5, acceleration time >70 milliseconds, and parvus-tardus waveform (small peak with slow upstroke) in intrarenal arteries 1, 2
The American College of Radiology suggests that Duplex ultrasound can be used regardless of renal function level, requires no contrast, and is cost-effective, but is operator-dependent and technically limited in obese patients or those with overlying bowel gas 3

CT Angiography has a sensitivity of 92-98% and specificity of 92-98%, and provides excellent anatomic detail of the renal arteries, accessory vessels, and aorta, but requires careful risk-benefit assessment in patients with impaired renal function due to contrast-induced nephropathy concerns 1, 3
MR Angiography has a sensitivity of 94-97% and specificity of 85-93%, and provides both anatomical and functional information, with non-contrast MRA techniques preferred in patients with impaired renal function to avoid nephrogenic systemic fibrosis 1, 3

In-stent restenosis surveillance requires higher thresholds: PSV ≥395 cm/s or RAR ≥5.1 for detecting ≥70% in-stent restenosis 1, 2, 4
Bilateral disease is difficult to quantify, but flash pulmonary edema is a key clinical clue, and the American College of Radiology suggests considering the hemodynamic effect of each side independently 1, 3
Fibromuscular dysplasia accounts for 10% of cases, typically in younger patients, and can be reliably graded using the continuity equation on ultrasound 3

The American College of Radiology suggests that perfusion pressure is generally not reduced until stenosis exceeds 70-75%, and a pressure drop >20 mmHg across a >50% stenosis is now classified as relevant for increased renin secretion 3
The ultimate criterion for renovascular hypertension is a fall in blood pressure after intervention (angioplasty, stenting, or surgery), not just anatomic stenosis, as recommended by the American College of Radiology 3