TOE is used intra-operatively to perform the following functions during cardiac surgery:
- Confirm the diagnosis
- Confirm valvular morphology and anatomy
- Assess suitability for novel valve implantation (Intuity or Perceval valve)
- Assessment for concurrent aortic regurgitation (and implications for cardioplegia administration)
- Assess LV morphology and function
2D AV SAX [30-60 degrees]
- Calcification
- Leaflet restriction
- Commissural fusion
- Area of the AV orifice by direct planimetry. This may be unreliable if the image is aligned either above or below the valve orifice which can lead to over or underestimation. Overall this is not a recommended method to quantify severity.
- Identification of trileaflet or bileaflet valve
Mid-oesophageal Long axis (MOLAX) view 100-140 degrees
In the MOLAX view measurements can be made of the following:
- LVOT width
- Aortic annulus - in mid systole at the hinge points. Males = 2.3-2.9cm, Females = 2.1-2.5cm
- Aortic sinuses - Male 3.4-4.0cm, Female 3.0-3.6cm
- Sinotubular junction - Male 2.9-3.6cm, Female 2.6-3.2cm
- Proximal aorta - Male 3.0cm, Female 2.7cm
Ensure that the image is through the center of the aorta and AV to avoid foreshortening errors and underestimating diameter.
Deep Transgastric VIew (Either 0 degrees or 90-100 degrees)
- The only view where accurate measurement of LVOT and AV gradients can be performed with TOE
- Accurate beam alignment is possible in 80-90% of patients. Note this view is uncomfortable in patients undergoing sedation or awake TOE and is often not performed for this reason
3D assessment of the AV
- More accurate measurement of the AV orifice (Machida et al)
- Enables more accurate measurement of the LVOT diameter