Description

Assessment of LVO involves measuring the mean velocity of blood flow across the ascending aorta from an apical five chamber view using pulsed wave Doppler and determining the diameter of the aortic root from a parasternal long-axis view using 2D. The aortic valve diameter is determined by measuring the distance between the two visible hinges of the aortic valve in early systole from the long axis parasternal view. The Doppler is obtained by placing the cursor of the PW just beyond the aortic valve in the 5 chamber view. Mean aortic velocity can be measured with the Doppler probe. The area under the wave form of the aortic systolic beat can be used to calculate the velocity time integral, which is a measure of the distance travelled by blood during a given beat. The heart rate should be calculated from the R-R interval obtained from ECG tracing of the aortic Doppler flow image. LVO expressed in ml/kg/min. To bring the left ventricular outflow tract and aortic valve into view from a 4 chamber view, the probe is rotated in a clockwise motion and angled slightly anterior.