The influence of respiration on criteria for transabdominal duplex examination of the splanchnic arteries in patients with suspected chronic splanchnic ischemia.

Background: Duplex ultrasound imaging of the mesenteric vessels is often used as a first diagnostic tool to evaluate the mesenteric circulation in patients with unexplained chronic abdominal symptoms. Several studies on duplex criteria have been published; however, most studies are small and included not exclusively patients with symptoms suggestive of chronic mesenteric syndrome (CMS). This study evaluated the contribution of respiration-monitored duplex ultrasound imaging in the diagnosis of stenosis or occlusion of the mesenteric arteries in patients suspected of CMS and thereby improves the definition of the criteria for stenosis.

Methods: Between 1999 and 2007, 779 consecutive patients presented to our tertiary referral center for evaluation and treatment of CMS. Mesenteric artery duplex ultrasound imaging and angiography of the abdominal aorta and its branches were performed in 324 patients. Angiography was considered the gold standard for verifying the presence or absence of arterial pathology. Results from duplex imaging and angiography were compared to determine the optimal duplex criteria for stenosis. In addition, the contribution of expiration and inspiration on duplex imaging and angiography were established.

Results: Significantly higher peak systolic and end-diastolic velocities were found in the celiac artery (CA) and superior mesenteric artery (SMA) during expiration than during inspiration. Receiver operating characteristic curve analyses found respiration-dependent cutoff values for CA and SMA stenosis. The values corresponding with the highest accuracy (minimal false-negative and false-positive results) were determined. Peak systolic velocities cutoff points during expiration and inspiration were 280 and 272 cm/s, respectively, for the CA and 268 and 205 cm/s for the SMA. The end-diastolic velocity cutoff points during expiration and inspiration were 57 and 84 cm/s, respectively, for the CA and 101 and 52 cm/s for the SMA. Sensitivity for different duplex parameters in detecting mesenteric stenosis was 66% to 78% and specificity was 77% to 86%.

Conclusions: This study proposes new criteria related to respiration for duplex ultrasound imaging of the mesenteric arteries in patients with symptoms suggestive of CMS. It emphasizes the importance of taking into account the effect of respiration on duplex parameters. The lower sensitivity and specificity in our study compared with other studies puts into perspective the position of duplex imaging in the work-up of patients with suspected CMS. Duplex results should be used as a guide, with a low threshold giving a higher negative predictive value and, consequently, a lower positive predictive value.