A comparison of Power Doppler with conventional sonographic imaging for the evaluation of renal artery stenosis

BACKGROUND: Power Doppler (PD) has improved diagnostic capabilities of vascular sonography, mainly because it is independent from the angle of insonation. We evaluated this technique in a prospective comparison with conventional imaging, consisting in Duplex and Color Doppler, for the evaluation of Renal Artery (RA) stenosis. METHODS: Sensitivity, specificity and predictive values of PD and conventional imaging were assessed in a blinded fashion on eighteen patients, 9 with angiographic evidence of unilateral RA stenosis (hypertensive patients) and 9 with angiographically normal arteries (control group). PD images were interpreted with an angiography-like criteria. RESULTS: In the control group both techniques allowed correct visualization of 16 out of the 18 normal arteries (93% specificity). Only in five hypertensive patients RA stenosis was correctly identified with conventional technique (56% sensitivity and 86% negative predictive value); PD was successful in all hypertensive patients (100% sensitivity and negative predictive value), since the operators could obtain in each case of RA stenosis a sharp color signal of the whole vessel with a clear "minus" at the point of narrowing of the lumen. All results were statistically significant (p < 0.01). CONCLUSIONS: This study demonstrates that PD is superior to conventional imaging, in terms of sensitivity and specificity, for the diagnosis of RA stenosis, because it allows a clear visualization of the whole stenotic vascular lumen. Especially if it is used in concert with the other sonographic techniques, PD can enable a more accurate imaging of renovascular disease with results that seem comparable to selective angiography

Endothelial dysfunction and coronary artery disease: new insights from reactive hyperemia test

Aim: The percentage variation of Resistance Index (△RI%) after reactive hyperemia test at the brachial artery is a marker of endothelial dysfunction that could be used as a surrogate indicator for the extent of coronary artery disease (CAD). We assessed flow-mediated dilatation (FMD) and △RI% in 39 consecutive patients undergoing coronary angiography.Methods: Patients were classified in groups 0 to 3 according to the number of diseased vessels and the SYNTAX score was calculated. The hyperemia reactive test was performed 1 day before to 3 days after coronary angiography.Results: Both FMD and △RI% decreased significantly from groups 0 to 3 (ANOVA P &lt; 0.001 and P = 0.002, respectively). Reduced △RI% was linearly associated with SYNTAX score (β = 0.34, P = 0.036). At multivariable modeling, impaired △RI% was the only significant independent predictor of the presence of CAD (OR = 1.28, 95%CI: 1.06-1.54, P = 0.01).Conclusion: This study shows that a reduced △RI% after reactive hyperemia test is observed in patients with CAD and that such reduction is related to the extent of the disease. Therefore, to evaluate FMD and △RI% at the brachial artery can reliably indicate the burden of CAD