39 patients scheduled for cardiac operation in general anaesthesia divided in 3 groups (13 per group): I. Patients with mild to moderate TI and normal RVSP (< 40mmHg) and mean PAP (< 25mmHg) II. Patients with mild to moderate TI and elevated RVSP (> 40mmHg) and mean PAP (> 25mmHg) Patients with severe TI (defined as Vena contracta > or equal 7mm, reversed systolic hepatic vein flow, proximal isovelocity surface area (PISA) radius > 9 mm, and very large central jet or eccentric wall impinging jet)