ECHOCARDIOGRAPHIC ASSESSMENT OF LEFT-VENTRICULAR FILLING DURING ISOFLURANE ANESTHESIA

Purpose: To determine the effect of isoflurane on left ventricular dia stolic function, as assessed by Doppler echocardiography. Methods: Ten patients with normal cardiovascular function were enrolled. Doppler m easurements of mitral inflow velocities, and pulmonary venous blood fl ow velocities were measured preoperatively (transthoracic echocardiogr aphy), and intraoperatively (transesophageal echocardiography) at isof lurane MAC 1 and MAC 1.5. Heart rate and blood pressure were measured concomitantly. Variables were compared with repeated measures ANOVA. R esults: Isoflurane at both doses caused equal decreases in mitral infl ow A(atrial systole) velocity (control: 43 +/- 12.3 cm.sec(-1) vs MAC 1: 31 +/- 6.0 cm . sec(-1) and MAC 1.5: 31.3 +/- 7.9 cm . sec(-1) P < 0.01), the deceleration time of the mitral inflow E (early) velocity ( control: 178 +/- 31.7 msec versus MAC 1: 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 1: 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 +/- 0.57 vs MAC 1: 2.0 +/- 0.6 and MAC 1.5: 2.2 +/- 0.78, P < 0.001). No changes in mitral inflow E or pulmo nary venous velocities were seen. Conclusion: The changes ill Doppler velocities of mitral inflow and pulmonary venous flow with isoflurane are not consistent with prolonged left ventricular relaxation nor incr eased myocardial restriction, but are,more likely the result of altera tions in left ventricular lending conditions and atrial systolic funct ion.