What is TOE (Transesophageal Echocardiogram) in cardiology?

What is TOE in Cardiology?

TOE (Transesophageal Echocardiography) is an ultrasound imaging technique that visualizes the heart and great vessels using a specialized probe inserted through the esophagus and stomach, providing superior image quality compared to standard transthoracic echocardiography due to the proximity of the transducer to cardiac structures without interference from lung or chest wall tissue. 1

Technical Description

• TOE utilizes a modified gastroscope housing an ultrasound transducer at its tip, positioned within the esophagus and stomach to obtain high-resolution cardiac images 2, 3
• The technique incorporates multiple imaging modalities including two-dimensional, three-dimensional echocardiography, pulsed and continuous wave Doppler, color flow Doppler, and tissue Doppler imaging 1
• Modern TOE probes offer high spatial and temporal resolution, enabling excellent visualization of thin and mobile cardiac structures 1

Key Advantages Over Transthoracic Echocardiography

• Superior diagnostic sensitivity: TOE increases sensitivity for detecting vegetations from 75% (with transthoracic echo) to 85-90%, and achieves approximately 99% sensitivity for native valve endocarditis 1, 4
• No radiation exposure and no requirement for ionic contrast injection 1
• Repeatability and portability for bedside assessment 1
• Particularly valuable when transthoracic windows are inadequate due to obesity, chronic lung disease, or mechanical ventilation 1

Primary Clinical Indications

Infective Endocarditis

• TOE should be performed in the majority of patients with suspected infective endocarditis due to superior image quality and sensitivity, except when high-quality transthoracic echocardiography is negative with low clinical suspicion 1
• For prosthetic valve endocarditis, TEE demonstrates 90% sensitivity compared to only 50% for transthoracic echo 4
• A negative TOE never completely rules out infective endocarditis; repeat TOE after 3-5 days if clinical suspicion persists 1, 5

Valvular Heart Disease

• Essential for complex valvular disease assessment, especially mitral disease and prosthetic valves 1
• Superior for defining the mechanism of mitral regurgitation and assessing severity 6
• Allows direct planimetry of aortic valve surface in approximately 85% of cases when transthoracic imaging is insufficient 6

Congenital Heart Disease

• Most common indication is evaluation of interatrial communications (atrial septal defects, patent foramen ovale) 1
• Critical for assessing suitability for percutaneous closure, including defect diameter, tissue rim adequacy (rim width <5 mm generally precludes device closure except at aortic side), and detection of additional defects 1
• 3D TOE offers improved spatial orientation with en-face views of the septum and defects 1

Aortic Diseases

• Confirms aortic dissection diagnosis with approximately 95% sensitivity and 99% specificity by demonstrating intimal flap 6
• Shows the site, type, and extent of aortic tears 2
• Crucial for pre-operative, intra-operative, and post-operative assessment of surgically treated aortic diseases 1

Procedural Guidance

• Integral for guiding percutaneous interventions including atrial septal defect closure, left atrial appendage occlusion, and mitral valve clip procedures 1
• Essential for transseptal puncture guidance and detection of procedural complications such as pericardial effusion 1

Thromboembolic Risk Assessment

• Superior for detecting left atrial or left atrial appendage thrombi 6
• Substantially higher yield than transthoracic echocardiography for diagnosing direct and indirect sources of cardioembolism 2

Contraindications

Absolute Contraindications

• History of dysphagia 2
• Current esophageal pathology 2
• Recent esophageal surgery 2

Relative Contraindications (Requiring Risk-Benefit Assessment)

• Esophageal varices 2
• Active upper gastrointestinal bleeding 2
• Oropharyngeal pathology 1
• Cervical injuries or anomalies with restricted neck mobility 1

Special Considerations

• In cyanotic patients, non-invasive oxygen saturation monitoring (pulse oximetry) is advised 1
• Particular care required in severe pulmonary hypertension patients; monitor saturation and avoid blood pressure spikes 1
• TOE is not routinely needed for diagnostic assessment unless transthoracic windows are inadequate and alternative modalities (cardiac MRI) are unavailable 1
• Ventilated, critically ill patients can safely undergo TOE 2