RESUMO
There is a strong association between pre-operative diastolic dysfunction and difficulty in weaning from cardiopulmonary bypass. We compared the effects of propofol and isoflurane on left ventricular diastolic function in patients with pre-existing diastolic dysfunction undergoing coronary artery bypass grafting. We randomly allocated 60 patients to receive either propofol or isoflurane anaesthesia, and assessed left ventricular diastolic function using transoesophageal echocardiography. We measured early (E), late (A) diastolic velocities, E/A ratio, A-wave duration and deceleration time using pulsed wave Doppler, and early (Em), late (Am) diastolic velocities of the mitral annulus, Em/Am ratio and isovolumetric relaxation time using tissue Doppler. We measured pulmonary venous flow velocity and recorded values for the peak systolic flow velocity (S), peak diastolic flow velocity (D), S/D ratio, peak reverse atrial flow velocity and duration of reverse atrial flow. All data were recorded immediately after tracheal intubation as a baseline, 5 min before sternotomy (T1 ), 5 min before aortic cannulation (T2 ) and 15 min after weaning from cardiopulmonary bypass (T3 ). Both propofol and isoflurane improved left ventricular diastolic function as evidenced by significant increases in E/A ratios, and significant decreases in deceleration time and isovolumetric relaxation time; the improvement was greater in the isoflurane group (between groups, p = 0.001 for both E/A ratio and deceleration time at T1 and T2 and p = 0.006 for isovolumetric relaxation time at both T1 and T2 ). Furthermore, Em/Am ratio, S, D and S/D ratios were significantly better in the isoflurane group. The administration of isoflurane during cardiac surgery improves diastolic function comparatively more than propofol.
