Echo-doppler to predict the outcome for renal artery stenosis

Not all patients with renal artery stenosis will benefit from angioplasty or surgery. For this reason it is not sufficient to diagnose the presence of renal artery stenosis, but one also has to evaluate its functional significance. Ultrasonographic detection of renal artery stenosis can be made with a sensitivity and specificity exceeding 90% by an experienced investigator. A combination of Doppler parameters making use of both direct and indirect signs of stenosis should be used. In our hands, a renal-renal ratio greater than 4 and--if this parameter was not measurable--an acceleration time longer than 70 msec was the best combination. The reversibility of hypertension or impaired renal function (i.e. the presence of renovascular hypertension or azotemia) after successful correction of renal artery stenosis can be assessed by measuring segmental artery resistance indices. A resistance index value greater than 0.80 makes a treatment effect highly unlikely, and these patients should not undergo angioplasty or surgery of their stenosis.