Renal doppler, renal artery stenosis, and renovascular hypertension: Direct and indirect duplex sonographic abnormalities in patients with renal artery stenosis

Tom Stavros, David Harshfield

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

There are two methods of duplex evaluation for renal artery stenosis (RAS): (a) direct interrogation of the main renal artery and (b) indirect duplex evaluation of the distal renal arterial tree (distal main renal artery, segmental or interlobar branches of the renal artery). Direct and indirect methods have comparable sensitivity (low 90% range) and specificity (mid-90% range) for detection of ≥60% RAS. Direct interrogation requires that the entire length of both renal arteries be evaluated and is plagued by a relatively high technical failure or incomplete examination rate, long examination times, and difficulties in measuring accurate velocities due to suboptimal angles of incidence. Indirect evaluation, on the other hand, is technically successful in the vast majority of cases and less time consuming than direct interrogation. We recommend the indirect method for initial evaluation, but direct interrogation whenever the indirect evaluation is equivocal or abnormal. Although less demanding than direct methods, indirect duplex methods still require a thorough understanding of Doppler principles and meticulous technique. Direct interrogation criteria for ≥60% RAS are (a) renal artery-to-aortic ratio (RAR) of ≥3.5 or (b) peak systolic velocity (PSV) ≥180 cm/s in association with poststenotic turbulence. Indirect parameters to diagnose ≥60% diameter RAS include acceleration time (AT) <.07 s, acceleration index (AI) <2.78 kHz/s2/MHz, acceleration (ACC) <3 m/s2, absence of the normal early systolic peak (ESP), difference in resistivity index between the ipsilateral and contralateral kidney (RID) <–5, and marked asymmetry in the shape of waveforms between the right and left kidneys or between upper-, mid-, and lower portions of one kidney. We found pattern recognition for loss of ESP the most expedient and sensitive parameter for 60% diameter RAS (91% sensitivity, 96% specificity). Limitations of indirect Doppler methods include insensitivity for 50% diameter RAS, inability to distinguish severe stenosis from occlusion, and insensitivity for stenosis in an accessory or segmental renal artery. In addition, bilateral indirect Doppler abnormalities may be due to occlusive disease proximal to the renal arteries (i.e., aortic coarctation) rather than bilateral RAS. Duplex sonography is useful to assess the effectiveness of revascularization procedures, [percutaneous transluminal angioplasty (PTA), stent placement, surgical graft placement]. After successful revascularization, indirect Doppler parameters return to normal immediately. Their failure to return to normal indicates a poor technical result and also predicts a poor blood pressure response to treatment. Patients with indirect Doppler abnormalities have higher systolic and diastolic blood pressures than those who have normal indirect Doppler parameters. Also, patients whose indirect Doppler parameters return to normal after revascularization have better blood pressure responses than those in whom they do not. A large negative RID (≤ = –10) in conjunction with loss of ESP may be able to prospectively predict that RAS is causing RVH. Renal artery diameter stenosis of 50% should not be used as the gold standard against which direct or indirect Doppler criteria is compared. A diameter of 60 to 75% RAS is required to cause renovascular hypertension (RVH), depending on plaque shape and peripheral impedance. Using 50% RAS as the gold standard falsely makes duplex evaluation appear less accurate. We recommend using >60% diameter angiographic RAS as the gold standard. Duplex sonographic screening of unselected hypertensive patients is not justified due to the low prevalence of disease in this group (1-2%). However, duplex sonography is effective in subgroups of hypertensive patients who have a ≥ 10% of RAS based on clinical selection criteria.

Original languageEnglish (US)
Pages (from-to)217-263
Number of pages47
JournalUltrasound quarterly
Volume12
Issue number4
DOIs
StatePublished - 1994
Externally publishedYes

Keywords

  • Acceleration
  • Acceleration index
  • Acceleration time
  • Blood flow dynamic
  • Doppler duplex sonography
  • Early systolic peak
  • Pulsus parvus
  • Pulsus tardus
  • Renal artery stenosis
  • Renovascular hypertension
  • Resistivity index difference

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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