Measurement of peak aortic jet velocity in the perioperative period-machine variability: implications for assessment of aortic stenosis severity

Variation in echocardiography machines and probes are not well described in the perioperative period. We aimed to compare the estimation of severity of aortic stenosis with transthoracic echocardiography (TTE) using two semi-portable ultrasound machines. Experienced cardiac anaesthetists performed a limited transthoracic echocardiogram with two different semi-portable ultrasound machines in patients with known aortic stenosis. The peak aortic jet velocity with continuous-wave Doppler and the time taken to obtain an acceptable envelope were recorded. The Sonosite M Turbo often underestimated the peak jet velocities (median jet velocity [IQR] 2.25 m/s [1.95 to 3.4] versus 3.85 m/s (3 to 4.2); P <0.001) and required more time to get a satisfactory envelope than the GE Vivid I. There was no statistically or clinically significant difference between the velocities obtained from the Vivid I and those measured on the patient's formal cardiology preoperative transthoracic echocardiogram (median [IQR]: 3.95 m/s [3.0 to 4.7]; P=0.3). However, the velocities obtained by the M Turbo were significantly lower than those obtained by the formal preoperative transthoracic echocardiogram (P <0.001). With the expansion of transthoracic echocardiography amongst anaesthetists, underestimation of the peak aortic jet velocity can significantly underestimate the severity of aortic stenosis with potentially lethal clinical consequences. Semi-portable ultrasound machines with echocardiographic capability are not necessarily equivalent and can result in underestimation of severity of aortic stenosis.