Transoesophageal echocardiography

Transoesophageal echocardiography is a two dimensional cardiac imaging technique similar to transthoracic echocardiography except that an oesophageal ultrasound transducer allows detection of posteriorly and deeply located structures beyond the scope of the transthoracic method.

TOE has increased the detection of potential cardiac sources of emboli by two to ten fold (1). These include left atrial spontaneous echo contrast due to low swirling blood flow in the left atrium, patent foramen ovale, atrial septal aneurysm and mitral valve abnormalities.

The main difficulty with TOE is its invasive nature. Many elderly stroke patients are unable to tolerate it and sedation is undesirable.

Notes:

• atrial fibrillation (AF) is the most-common arrhythmia in the elderly population (age >65 years)
  • left atrial appendage (LAA) is the main location of thrombus formation, predominantly in patients with nonvalvular AF
  • gold-standard modality for assessment of SEC and thrombus in the LAA is echocardiography, particularly transoesophageal echocardiography (TEE) - however alternatives such as cardiac CT and cardiac MRI may have advantages

Reference:

• Daniel WG, Mugge A. Transesophageal echocardiography. NEJM 1995;332: 1268-77.
• Romero J et al. Cardiac imaging for assessment of left atrial appendage stasis and thrombosis.Nat Rev Cardiol. 2014 Jun 10.