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Renal artery stenosis: evaluation of Doppler US after inhibition of angiotensin-converting enzyme with captopril.

PURPOSE
To evaluate the modifications of Doppler ultrasound waveform morphology after inhibition of angiotensin-converting enzyme with captopril to increase the sensitivity of Doppler sonography in detecting renal artery stenosis.


MATERIALS AND METHODS
Sixty-two renal arteries were studied in 31 hypertensive patients who underwent Doppler scanning before and 1 hour after administration of captopril prior to undergoing angiography. Pattern recognition criteria were applied to classify the Doppler waveforms as having a normal or pulsus tardus configuration. Doppler scanning results were compared with those of arteriography.


RESULTS
On the basis of recognition of the pulsus tardus, precaptopril Doppler scanning showed 13 (68%) of 19 significant renal artery stenoses found at angiography (95% confidence interval, 0.43, 0.85), whereas 19 (100%) of 19 stenoses were detected with postcaptopril Doppler scanning (95% confidence interval, 0.85, 1.0).


CONCLUSION
Captopril significantly (95% confidence intervals) increases Doppler scanning sensitivity in detecting renal artery stenoses by inducing or enhancing the pulsus tardus distal to a significant renal artery stenosis.