• Brian Cowie, Charles Bitcon, and Roman Kluger.
• From the Department of Anaesthesia and Acute Pain Medicine, St. Vincent's Hospital Melbourne, Fitzroy, Victoria, Australia (BC, CB, RK).
• Eur J Anaesthesiol. 2021 Dec 1; 38 (12): 125312611253-1261.

BackgroundAssessment of left ventricular outflow tract (LVOT) area is a key component of quantification of aortic stenosis and stroke volume. Current international guidelines recommend measurement of the LVOT diameter with two-dimensional (2D) echocardiography and assume a circle. This may lead to erroneous measures of aortic valve area and adversely affect peri-operative decision making. Multiplane orthogonal (biplane) and three-dimensional (3D) echocardiography imaging may allow more accurate calculation of LVOT, aortic valve area and stroke volume.ObjectiveTo evaluate the shape and area of the LVOT with conventional 2D diameter, short axis cross-sectional planimetry with biplane imaging and 3D multiplane reconstruction in patients undergoing cardiac surgery with transoesophageal echocardiography (TOE).DesignA retrospective observational study.SettingA single centre university hospital.Patients119 patients undergoing cardiac surgery with TOE.InterventionsNone.Main Outcome MeasuresMeasurements of the shape and area of the LVOT with standard 2D TOE, short axis biplane imaging and 3D TOE.ResultsThe LVOT shape is elliptical in 70% of patients. The (mean ± SD, [range]) LVOT cross-sectional area with 2D TOE was 4.29 cm2 ± 0.98, [2.46 to 6.70], with biplane was 4.68 cm2 ± 1.03, [2.92 to 7.30] and with 3D was 4.59 cm2 ± 0.99, [2.78 to 7.10]. There was a statistically significant difference (P < 0.001) in the three pairwise comparisons. 2D LVOT area had large bias (7 to 9%) and wider limits of agreement (LOA) with both biplane and 3D LVOT area (-17 to 36%). Biplane and 3D LVOT areas had small bias (1.8%) with relatively narrow LOA (-8 to 11%).Conclusions2D diameter measures of the LVOT assuming a circle underestimate LVOT area, underestimate aortic valve area and increase the apparent severity of aortic stenosis. This may lead to inappropriate aortic valve intervention. In a busy operating room environment, we suggest that for the calculation of stroke volume and aortic valve area, LVOT area is measured with biplane imaging.Trial RegistrationObservational study with no interventions so trial not registered.Copyright © 2021 European Society of Anaesthesiology and Intensive Care. Unauthorized reproduction of this article is prohibited.

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