Duplex criteria for native superior mesenteric artery stenosis overestimate stenosis in stented superior mesenteric arteries.

OBJECTIVES: Superior mesenteric artery (SMA) duplex scanning is utilized to screen for high-grade (>or=70%) SMA stenosis (peak systolic velocity [PSV] >or=275 cm/second) and for follow-up of SMA bypass grafts and stents. Expected duplex scan findings in SMA bypass grafts have been recently reported. There is, however, little information correlating duplex scans from stented SMAs to procedural angiograms in patients treated for high-grade (>or=70%) SMA stenosis. We report validation of duplex scan criteria for high-grade native artery SMA stenosis, and also duplex scan examined results after SMA stent placement correlated with angiograms and angiographic measured pressure gradients pre- and post-SMA stent placement. METHODS AND
RESULTS: Thirty-five patients with symptoms consistent with mesenteric ischemia were treated with SMA stents. Pre-intervention angiography demonstrated >70% SMA stenosis or SMA occlusion in all but 3 patients. Pre-intervention pressure gradients were obtained in 20 stenotic but patent SMAs and averaged 57 +/- 38 mm Hg; range, 15 to 187 mm Hg. Eighteen of the patients had SMA duplex scan prior to angiography, and 17 demonstrated an SMA PSV >or=275 cm/second or no flow, (mean 450 +/- 152 cm/second in patent arteries; range, 256 to 770 cm/second). Post-stent placement angiography demonstrated <30% SMA stenosis in all 35 patients. Post-stent pressure gradients were obtained in 22 patients and averaged 11 +/- 13 mm Hg; range, 0 to 45 mm Hg, (P < .001 compared to pre-stent pressure gradients in a paired test) and were elevated in patients with >or=60% celiac artery stenosis compared with those with <60% celiac artery stenosis (P < .006). Mean early post-stent duplex PSV scans obtained in 13 patients, were 336 +/- 45 cm/second; range, 279 to 416 cm/second (P = .011 compared to pre-stent PSVs).
CONCLUSION: SMA stenting provides good anatomic results and significantly reduces measured pressure gradients. Duplex scans measured SMA PSVs are reduced post-stent placement but despite good angiographic results remain above criteria predicting high-grade native artery SMA stenosis. Duplex scan criteria developed to identify high-grade native artery SMA stenosis accurately predict high-grade native artery SMA stenosis but overestimate stenosis in stented SMAs. New duplex scan criteria are required to predict high-grade stenosis in stented SMAs.