Background : The acute effects of β-blockers may be different from chronic; mechanisms underlying this difference are poorly elucidated.
Aim : To assess portal pressure and its pathophysiological determinants after acute and chronic administration of nadolol.
Methods : In 24 patients with cirrhosis and portal hypertension hepatic venous pressure gradient, portal blood flow and resistance to portal blood flow were measured before, 60–90 min after acute administration of nadolol, and after 1 month. Patients were good-responders if hepatic venous pressure gradient was ≤12 mmHg, or decreased by at least 20%.
Results : Eleven and 13 patients were good- and poor-responders to acute administration, respectively. Acute poor-responders showed a lower decrease in portal blood flow (P = 0.04) and a less evident decrease in mean arterial pressure (P < 0.001). Eleven and 13 patients were good- and poor-responders to chronic administration, respectively. Chronic poor-responders showed a larger increase in resistance to portal blood flow compared with good-responders (P = 0.01).
Disagreement between acute and chronic effects was seen in 12 patients: six were acute good-responders chronic poor-responders and six were acute poor-responders chronic good-responders. Acute good-responders chronic poor-responders patients had the smallest decreases in portal blood flow and in mean arterial pressure after acute administration, while acute poor-responders chronic good-responders showed the largest (P = 0.05 and 0.01).
Conclusions : Disagreement between acute and chronic effects of nadolol on hepatic venous pressure gradient is common. The mechanism responsible is complex, the acute effect being mainly modulated by arterial hypotension and the chronic effect by changes in portal resistance.