The six TEE windows any CRNA doing cardiac surgery has to know and be able to find for the surgeon.
Evaluation of LV size, wall thickness, and pumping strength (ejection fraction). While ME 4 is excellent for visualizing most segments, it may underestimate apical function due to chamber foreshortening. In addition the ME 4 is very sensitive in identifying valvular pathologies such as mitral regurgitation and assessing whether the leak is “functional” (due to chamber dilation) or structural (flail leaflets, chordal rupture)
Provides assessment of the aortic valve and second look at the mitral valve which is critical for the patient whose heart failure may be driven by valvular disease such as aortic insufficiency or vegetation. Also offers a look at two more LV walls and dimensions/sectors.
Reduced LV systolic function with decreased thickening and motion of the LV walls may be seen in the TG SAX view. In addition increased left ventricular end-diastolic dimensions and volume are seen along with reduced ejection fraction (<30%). This view is probably the best overall assessment of global LV function and filling.
An essential role of perioperative TEE is assessment f left ventricular function. Using Ohm's Law (Current=Flow x Resistance), BP=CO x SVR. To this end if HR x SV =CO, and HR is known and manipulated, SV and LV function is key. While Simpson's Law of Discs is the most accurate, "Eyeball EF" is the fastest and has the highest utility.
Again utilizing Ohm's Law, if HR is known and manipulated SV may be easily assessed using TEE. Here we have euvolemia on the left and the "kissing paps" on the right, indicating plenty of room for volume to increase SV and BP.
While TEE and wall motion is more specific (84%) than ECG in regards to myocardial ischemia, there are 17 TEE views required to rule out ischemia. Ischemic segments fail to thicken properly during systole, seen here as anterolateral ischemia.
Once again, if HR is is known LV filling and function is dependent on RV contribution such that if RV function is down then a different approach to Ohm's Law is necessary including SVR manipulation. In other words with a very afterload dependent RV, perhaps vasopressin and tidal volume/PEEP optimization is key.
Key findings in the ME 4 include tricuspid regurgitation (>2.5 m/s suggests pulmonary HTN) and RV dilation as measured with calipers mid-RV (>3.3 cm). Also abnormal septal motion is appreciated and the RV is no longer 1/3 to 1/2 the size of the LV, but the same size if not larger. While TAPSE is used for TTE it is inconsistent with TEE.
Often the "D" sign is noticed (the interventricular septum flattens or shifts towards the LV), but with slight lateral rotation the RV is seen as moderately to severely dilated.
Using calipers dimensions in 2D greater than 1.5 cm requires pericardial window while less than 1.5 cm may be managed with pericardiocentesis. As well a "trampoline" right atrium is indicative of significant pericardial effusion. Here a trip to the operating room is indicated...
TEE distinguishes between true and false lumens based on specific characteristics. The true lumen expands during systole and shows forward flow on color flow Doppler, while the false lumen may contain spontaneous echo contrast (due to blood stasis) or even thrombus. An intimal flap is present which is a mobile linear line within the aortic lumen. The ME Ascending Aorta SAX view offers an en face view of the ascending aorta and is key in assessing for this pathology.
The ME Ascending Aorta LAX view offers the ability to identify the specific site of the intimal tear where blood flows from the true to false lumen as well as any aortic regurgitation or aortic valve involvement. Additional TEE views may need to assess for descending aorta involvement or other complications including tamponade, myocardial ischemia or arch/left subclavian artery involvement.
Major limitations of transesophageal echo include "blind spots" in the distal ascending aorta and proximal aortic arch caused by interference from the trachea. However as with positioning of an intra-aortic balloon pump the upper esophageal SAX view may offer a view of the left subclavian artery, though typically a right radial brachial artery is used for monitoring if not a femoral artery.
Descending aortic dissection may be more easily managed by TEVAR but regardless TEE is much faster than trip to the CT/MRI. Here a descending thoracic aneurysm is captured simultaneously ME Descending Aorta Short and Long Axis with the use of Biplane (X-Plane).
Key findings for PE focus on signs of right ventricular strain and direct visualization of clots. McConnell's sign is a highly specific pattern of RV dysfunction characterized by akinesia of the RV free wall with preserved apical contrctility as seen here in this ME 4 view. RV dilation is common including an RV/LV diameter ratio >0.9. Often present along with severe RV dilation is severe tricuspid regurgitation with TR jet velocity greater than 2.5 m/s.
Directly seeing a thrombus is definitive but rare, occurring in less than 5% o f cases as it embolizes distally. However occasionally a large saddle embolus (as seen in this ME Ascending SAX view) may be seen at the bifurcation of the main pulmonary artery along with increased flow velocity from the occlusion. In addition the superior vena cava may been as severely dilated indicative of the elevated CVP.
Along with RV/LV diameter ratio >0.9 TEE demonstrates with interventricular flattening or "D" shaped LV as seen in this TG SAX view. Interventricular bowing towards the left ventricular occurs, with underfilling of the LV and severe hypotension and hypoperfusion.
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