Daily variation of azygos and portal blood flow and the effect of propranolol administration once an evening in cirrhotics

Background/Aims: Esophageal variceal bleeding occur more often at night, however, the mechanism for this remains unclear. This study investigated the daily variation of azygos blood flow (AzBF) and portal blood flow (PBF) and the effects of propranolol administration given once in evening in cirrhotics. Methods: Blood flow were measured using magnetic resonance imaging. Hemodynamic parameters were determined at 08:00, 16:00 24:00 and again 08:00 h, and were measured at baseline and after 14 days oral administration of propranolol (30 mg, n=7) or placebo (n=7) at 19:00 h in 14 patients. Results: A daily fluctuation of AzBF and PBF was observed, peaking at 24:00 h in nine patients. In three other patients, peak AzBF and PBF were observed both at 16:00 and 24:00 h. Two patients were constant throughout the day. When the daily variation was compared, ANOVA showed a significant difference (P<0.001). Propranolol administration at 19:00 h reduced AzBF (−40.7±17.9% vs. baseline, P<0.001) and PBF (−26.5±10.7% vs. baseline, P<0.01) at 24:00 h. Conclusions: We found that in most cirrhotics, AzBF and PBF peaks at midnight. Dosing of propranolol in the evening may be important for its role in preventing variceal bleeding.