LVOT-VTI

How to measure LVOT-VTI

Step 1 —Apical 5-chamber view or Apical 3-chamber (apical long-axis) view

You want the ultrasound beam to be as parallel as possible to LVOT blood flow.

Step 2 — Use PW Doppler

Place the pulsed-wave Doppler sample volume in the LVOT, usually approximately 5 mm proximal to the aortic valve.

Important: Do not place the PW Doppler sample inside the aortic valve jet.

• LVOT location is confirmed if VTI trace is followed by Closing click
• if both an aortic valve opening click and closing click are visible/audible, that means PW sample is too close to the aortic valve.
• If both clicks Absent then cursor location is in LV cavity.

Step 3 — Record several beats

Trace the dense outer envelope of the systolic Doppler waveform.

For sinus rhythm, usually average 3–5 beats.

With atrial fibrillation or significant beat-to-beat variation, average more beats, commonly 5–10, using appropriately selected beats.

LVOT-VTI Normal Value 18–22 cm(its is surrogate of stroke volume)

LVOT-VTI Variability

LVOT-VTI variability is a dynamic echocardiographic parameter used to assess preload responsiveness—i.e., whether stroke volume is likely to increase after a fluid challenge.

A large respiratory variation suggests that stroke volume is changing significantly with respiration, which can indicate preload dependence.

In an appropriate patient, a high LVOT-VTI variation (>10%) therefore suggests that fluid administration may increase stroke volume.

When is it reliable?

• controlled ventilation
• adequate tidal volume(8ml/Kg)
• no significant spontaneous respiratory effort
• sinus rhythm
• no major RV failure

For spontaneously breathing patients, consider PLR + LVOT-VTI:

1. Measure baseline LVOT-VTI.
2. Perform passive leg raising.
3. Re-measure LVOT-VTI.
4. A meaningful increase indicates that increasing preload increases stroke volume → fluid responsive.