Echocardiographic assessment of left ven- tricular filling during isoflurane anaesthesia

Purpose: To determine the effect of isoflurane on leJ~ ventricular diastolic function, as assessed by Doppler echocardiography. Methods: Ten patients with normal cardiovascular function were enrolled. Doppler measurements" of mitral inflow velocities, and pulmonary venous blood flow velocities were measured preoperatively (transthoracic echocardiography), and intraoperatively (transesophageal echocardiography) at isoflurane MAC I and MAC 1.5. Heart rate and blood pressure were measured concomitantly. Variables were compared with repeated measures ANOVA. Results: Isoflurane at both doses caused equal decreases in mitral inflow A(atrial systole) velocity (control: 43 cm.sec -I vs MAC I: 31  6.0 cm.sec -t and MAC 1.5:31.3  7.9 cm .sec -t P < 0.01), the deceleration time of the mitral inflow E (early) velocity (control: 178  31.7 msec versus MAC I: 127  38.3 msec and MAC 1.5:137  28.4 msec, P < 0.01), and mean blood pressure (control: 91.1  15.4 mmHg versus MAC !: 76.1 + 8.8 mmHg and MAC 1.5:71.9  6.2 mmHg, P < 0.002). Isoflurane at both doses caused an equal increase in the E./A ratio (control: 1.5 -e 0.57 vs" MAC I: 2.0 +0.6 and MAC 1.5:2.2  0.78, P < 0.01). No changes in mitral inflow E or pulmonary venous velocities were seen.