TEE: Cannula Placement
Advanced, Organ-Based and Clinical Sciences
Transesophageal echocardiography (TEE) is frequently used during cardiac surgery to guide the placement of wires and catheters for cardiopulmonary bypass, extracorporeal membrane oxygenation (ECMO), or cardioplegia catheters.
The most common use is to guide the placement of a femorally inserted venous inflow cannula for the bypass circuit. To achieve maximum flows this catheter should be positioned at the junction of the vena cava and the right atrium. The ideal view for confirming the correct position of a catheter at the SVC-RA junction is the bicaval view. This view allows the operator to see both the SVC and IVC as well as the right atrium. The bicaval view is obtained by positioning the probe in the mid-esophagus and setting the omniplane angle to 90-100 degrees.
To image a femorally inserted arterial wire or outflow cannula for bypass a descending aorta short axis view is used. This view is obtained by setting the omniplane angle at 0, turning the probe to the left until the descending aorta comes into view, and advancing the probe until the tip of the catheter or wire is visualized.
During minimally invasive cardiac surgery a coronary sinus catheter may be placed into the coronary sinus to provide retrograde cardioplegia. The modified bicaval view is usually ideal for imaging the placement of a coronary sinus catheter. To achieve a modified bicaval view, start at the midesophageal bicaval view and increase the omniplane angle until the coronary sinus and superior vena cava are seen at either end of the interatrial septum. At times a deep 4-chamber view may provide better imaging of the coronary sinus. This view is obtained by advancing the probe from a typical 4-chamber view and retroflexing until the tricuspid valve, coronary sinus, and IVC are seen.
TEE may also be used to confirm the position of ECMO cannulae, particularly the Avalon bicaval, dual lumen cannula for veno-venous ECMO, which is inserted in the internal jugular vein. Similar to confirming the position of femorally inserted venous catheters, a bicaval view is typically used to confirm appropriate catheter positioning. However, it is very important to confirm proper orientation of flow of the oxygenated blood returning to the heart. Color flow Doppler is useful to determine that the jet from the outflow orifice of the cannula is directed through the tricuspid valve.