Image Acquisition
Parasternal Long Assessment of LVOT
- Place cardiac probe at nipple line near the left side of sternum. Slide on anterior chest until obtain view.
- Center the heart on screen.
- Rotate = length the LV/open the LVOT.
- Sweep/fan to widen the LV. Freeze image and zoom into LVOT.
- Click 'calcs' then LV function then LVOT VTI.
- Measure the LVOT diameter in cm during systole with aortic valve open (use cineloop for this).
- Click camera to save.
VTI Determination
- Obtain apical 4 chamber view (see prior slides for details).
- Fan/sweep probe + obtain apical 5 chamber view.
- Place pulse wave doppler place at the LVOT. initiate doppler then freeze image.
- Click back into calcs, LV function. Now click VTI and trace the LVOT VTI doppler tracing. Machine will calculate VTI.
- Click camera to save image.
Cardiac Output Calculation
- Determine heart rate.
- Math Calculation:
- Use the LVOT diameter to find LVOT area: Area = pi * radius ^2.
- Cardiac output (ml/min) = LVOT area * LVOT VTI * heart rate.
- Note: the machine will do this entirely in the calcs section.
- Assess for improvements in your cardiac output following intervention (ie fluid bolus, starting inotropes).