6 TOE Instrumentation

Question 1

What are the types of TOE transducer and how is the TOE transducer manipulated?

Answer 1

Monoplane, biplane and multiplane.

Multiplane probes include a transducer at the tip of the probe which is able to rotate 180° so the heart is visualised in all planes.

Advancing/withdrawing, rotating and flexing (left/right and anteriorly/posteriorly).

Question 2

What are the indications for TOE?

Answer 2

Cardiac embolic source, thromboembolic risk in AF (guide anticoagulation and cardioversion), suspected or known IE, aortic diseases (e.g. aortic dissection), valvular regurgitation assessment for surgical repair, prosthetic valves, cardiac masses, congenital heart disease and intracardiac shunts (e.g. ASD or PFO).

Question 3

What are the contraindications for TOE?

Answer 3

The absolute contraindications for TOE include patient refusal, cervical spine instability and/or abnormalities increasing the risk of oesophageal or gastric perforation (e.g. oesophageal obstruction, oesophageal trauma, oesophageal fistula or diverticulum).

The relative contraindications for TOE include clotting disorders, large hiatus hernia, oesophageal varices and/or upper gastrointestinal haemorrhage.

Question 4

Why is TOE superior to TTE?

Answer 4

In TOE, the probe is positioned in the patient’s oesophagus so the probe is closer to the heart. Therefore, the ultrasound penetration is lower so the ultrasound frequency is higher. Therefore, the image resolution and image quality are superior.

Question 5

What are the TOE views?

Answer 5

Upper oesophageal, mid oesophageal, transgastric and deep transgastric.

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Question 6

What are the considerations with TOE?

Answer 6

Monitoring
Monitor the patient’s ECG, BP, oximetry, airway and response (sedation).

Safety

Infection
TOE transducers do not need to be sterile but do need to be cleaned and decontaminated.

Question 7

Describe the TOE protocol.

Answer 7

Before the TOE, ensure the patient is nil by mouth 6 hours before the TOE, acquire IV access via a cannula, check the patient’s blood glucose (diabetes) and INR (anticoagulation) levels.

During the TOE, administer local anaesthetic throat spray and administer conscious sedation (flumazenil
reverses midazolam).

During the TOE, pass the probe into the mouth and down the oesophagus but do not advance against resistance. Monitor the patient for complications (trauma, arrhythmias and sedative related risks).

After the TOE, check for complications and clean the probe.