What is the role of ultrasonography in the workup of renovascular hypertension (RVHT)?

Updated: Dec 01, 2020
  • Author: Rebecca J Schmidt, DO, FACP, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Many authors believe that diagnostic imaging should begin with doppler ultrasonography of the kidneys and abdomen, which is useful in identifying renal disease and abdominal masses. This technique potentially can detect both unilateral and bilateral disease and also can be used to detect recurrent stenosis in patients previously treated with angioplasty or surgery. It should be kept in mind, however, that renal ultrasonographic findings are insufficient to rule out the need for angiography.

Doppler ultrasonography provides both anatomic and functional assessment of the renal arteries. Direct visualization of the main renal arteries (B-mode imaging) is combined with measurement (via Doppler) of intrarenal pressures and velocities (by waveform) to achieve a sensitivity of 72-92% for detecting RAS of 70% or greater.

Doppler ultrasonographic evaluation of renal resistance indices (1 – end diastolic velocity/maximum systolic velocity × 100) can be used to classify patients as potential responders or nonresponders to intervention (ie, a renal resistance index exceeding 80% implies a low likelihood that correction of the stenosis will eventuate in improved blood pressure control or kidney function). [23, 24, 25]

Important disadvantages of this modality include the possibility that bowel gas can interfere with direct visualization of the renal arteries (50-90% of the time). Doppler measurements are hampered very infrequently (0-2%). Furthermore, this modality is time-consuming to perform (requiring approximately 2 hours) and is a technically difficult procedure with a steep learning curve, making success highly operator-dependent.


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