Longitudinal views are obtained at the same levels as transverse ones, that is:Detailed longitudinal images should be obtained at these levels. Important views are:
A. Transgastric views
The transgastric two-chamber view is of value in assessing the left atrium, left ventricle, the medial scallop of the posterior mitral leaflet and lateral segment of the anterior mitral leaflet, asynergy of the anterior and posterior walls of the left ventricle, and (occasionally) visualisation of the LVOT.
- Two chamber view (LA, LV, MV) - 'TG 2 Chamber'
- Long axis view (LA, LV, MV, Ao) - 'TG LAX'
- Deep TG Long axis view - 'Deep TG LAX'
B. Mid-oesophageal views
- This view provides an excellent four chamber perspective, and good views of the aortic valve. It is tricky to obtain (and particularly uncomfortable in the awake patient) but may provide valuable information.
The mid-oesophageal two-chamber view is useful in visualisation of the left atrial appendage (as well as the LA and LV), the middle scallop of the PML, the lateral segment of the AML, and abnormal wall motion in the posterior, anterior and apical LV.
The ridges of the pectinate muscles in the left atrial appendage are sometimes interpreted as "clots". One must also be careful to distinguish the LAA from the left upper pulmonary vein! If fluid is present in the oblique sinus around the LAA, this may be falsely interpreted as the LAA! In addition the junction of the LA and LUPV is so often mis-interpreted as being a thrombus that this has been nicknamed the "warfarin ridge"!
- Two chamber view (LA, LV, MV) - 'ME 2 Chamber'
- Two chamber view + LAA
In the basal longitudinal plane views, a host of structures can be seen if one rotates the probe from left (counter-clockwise) to extreme right (clockwise). As we rotate the probe from the left, these are in turn:
- C. Basal views
The atrial septal view is particularly good for visualising shunts (together with echocardiographic contrast administration i.e. saline with microbubbles).
- the LV inflow and left upper pulmonary vein,
- the RVOT,
- in the "middle" the proximal ascending aorta and fossa ovalis, and then moving right
- the SVC, a good view of the atrial septum and sinus venosus (with long axis IVC, including where the IVC meets the right atrium - the Eustachian valve), and finally
- the right upper pulmonary vein.
A prominent Eustachian valve can resemble a mass in the right atrium. Similarly, the point of junction of the right atrium and superior vena cava can be falsely interpreted as a "mass".
- LV inflow, LUPV
- RVOT, MPA
- Long axis ascending aorta - 'ME AV LAX'
- SVC, atrial septal long axis - 'ME bicaval'
- LVOT long axis