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246 ANTROPYLORODUODENAL COORDINATION IN HUMANS: A VIDEOFLUOROSCOPIC IMAGE ANALYSIS STUDY P Bercik, J Huizinga, J Rawlinson, SM Collins, D Armstrong BACKGROUND: Studies on human gastro-duodenal motility have shown that despite distinct motor patterns in the stomach and duodenum, peristaltic contractions may propagate across the pylorus. Understanding mechanisms of antropyloroduodenal (APD) coordination is important since its perturbation may be the basis of upper GI dysmotility. Here we investigate APD coordination in humans using videofluoroscopy combined with video image analysis.
McMaster University, Hamilton, Ontario
METHODS: Ten healthy volunteers (6M, age 20-50) were studied on three occasions, after ingestion of 300 ml of 20% barium only, or barium mixed with either 25% dextrose or 1% guar gum (just pourable consistency). Video images (3/s) were acquired in five 1-minute sessions over a 40-min study period. Image analysis generated spatiotemporal maps to determine the frequency, velocity and direction of contractions as described previously (Bercik, Gastroenterology 2000). Results from spatio-temporal maps were verified by inspecting corresponding video sequences.
RESULTS: In total, 205 gastric and 182 duodenal contractions, of which 94 originated within 3 cm from pylorus, were analysed for APD coordination. Most of the time, regular gastric contractions propagated until the pylorus. Peristaltic duodenal contractions mostly originated before the antral wave reached pylorus; 27% of them started 6-8 seconds prior and only 4% within 1 second before or after the end of antral wave. Duodenal peristaltic contractions were mostly preceded by pyloric opening with subsequent flow of gastric contents into proximal duodenum, or rarely by retrograde flow of contents from distal duodenum. On both occasions this led to a 22% increase in proximal duodenal diameter compared to periods with no peristalsis.
CONCLUSIONS: Antral contractions do not propagate into the duodenum. Duodenal peristaltic contractions seem to be initiated by distension of the duodenal bulb. The pylorus plays a crucial role in APD coordination by determining the amount of gastric contents that passes into the duodenum and triggers duodenal peristalsis.