Echocardiographic assessment of left ventricular filling during isoflurane anaesthesia.
OBJECTIVE
To determine the effect of isoflurane on left 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 1 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 +/- 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 < 0.01). No changes in mitral inflow E or pulmonary venous velocities were seen.


CONCLUSIONS
The changes in Doppler velocities of mitral inflow and pulmonary venous flow with isoflurane are not consistent with prolonged left ventricular relaxation nor increased myocardial restriction, but are more likely the result of alterations in left ventricular loading conditions and atrial systolic function.
Oxorn
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D
Department of Anaesthesia, Sunnybrook Health Science Centre, Toronto Ontario, Canada. donald.oxorn@utoronto.ca
Edelist
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Harrington
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Tsang
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D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D016275:Atrial Function / Q000187:drug effects; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D003971:Diastole / Q000187:drug effects; D015150:Echocardiography, Doppler; D017548:Echocardiography, Transesophageal; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007430:Intraoperative Care; D007530:Isoflurane / Q000008:administration & dosage*; D008875:Middle Aged; D008943:Mitral Valve / Q000187:drug effects / Q000502:physiology; D009200:Myocardial Contraction / Q000187:drug effects; D011667:Pulmonary Veins / Q000187:drug effects / Q000502:physiology; D013599:Systole / Q000187:drug effects; D016277:Ventricular Function, Left / Q000187:drug effects*
D018685:Anesthetics, Inhalation; D007530:Isoflurane