Intraoperative Monitoring and Transesophageal Echocardiography

Intraoperative monitoring in cardiac surgery is the continuous assessment of a patient's circulation and cardiac function during an operation. Its central imaging tool is transesophageal echocardiography (TEE), an ultrasound probe placed in the oesophagus directly behind the heart, which gives real-time, high-resolution views of cardiac structure and function to guide and confirm the surgical result.

Definition

Transesophageal echocardiography is an ultrasound imaging technique in which a probe positioned in the oesophagus produces real-time images of the heart and great vessels; used intraoperatively, it monitors cardiac function and structure and helps assess the adequacy of a surgical repair.

Scope

This topic covers the role of intraoperative monitoring in cardiac surgery and, in particular, transesophageal echocardiography: what it visualizes, how it informs surgical decisions, and the standardized examination it is built around. It is an educational reference, not a clinical protocol or a basis for diagnostic or treatment decisions.

Core questions

• What does intraoperative monitoring aim to detect during cardiac surgery?
• Why is the transesophageal window used rather than surface imaging?
• What can TEE show about valves, ventricular function, and de-airing?
• How is a comprehensive intraoperative examination standardized?

Key concepts

• Real-time intraoperative imaging
• Transesophageal acoustic window
• Assessment of ventricular function and filling
• Valve repair and replacement assessment
• Detection of intracardiac air (de-airing)
• Standardized comprehensive examination views

Mechanisms

Because the oesophagus lies directly behind the heart, a transesophageal probe images cardiac structures without the lung and chest-wall interference that limits surface echocardiography, yielding clear views of the valves, ventricles, atria, and aorta. Intraoperatively, this lets the team assess ventricular contractility and filling, characterize valve pathology before repair, and immediately verify the result afterwards - for example, checking a mitral repair for residual regurgitation while the patient is still in the operating room. TEE also detects retained intracardiac air during de-airing and helps monitor cannula position and haemodynamics. To make examinations complete and reproducible, professional societies define a standardized set of imaging planes that together constitute a comprehensive intraoperative study, complementing other monitoring such as electrocardiography, arterial and venous pressures, and oxygenation.

Clinical relevance

Intraoperative TEE is widely used in cardiac surgery to guide decisions and confirm repair adequacy, and familiarity with its role supports understanding of perioperative cardiac care. This entry describes the technique's purpose and capabilities; it is a reference and not a source of diagnostic interpretation or treatment guidance for individual cases.

Evidence & guidelines

Practice in this area is shaped by society guidelines, including the American Society of Echocardiography / Society of Cardiovascular Anesthesiologists recommendations for a comprehensive transesophageal examination and the American Society of Anesthesiologists / SCA practice guidelines for perioperative TEE. These documents define indications and the standardized examination rather than test a single intervention.

History

Transesophageal echocardiography developed from the 1970s and matured with multiplane probes in the 1990s, by which time it had become a routine intraoperative monitor in cardiac surgery. Standardized examination guidelines published from 1999 onward, and updated subsequently, codified the imaging planes and indications that define contemporary intraoperative practice.

Key figures

• Rebecca T. Hahn
• Joseph S. Shanewise
• Michael K. Cahalan

Seminal works

• shanewise-1999
• hahn-2013
• asa-sca-2010

Frequently asked questions

Why is the echocardiography probe placed in the oesophagus during heart surgery?

The oesophagus sits immediately behind the heart, so an ultrasound probe there gives clear, real-time images of cardiac structures without interference from the lungs or chest wall, which is ideal for monitoring during an operation.

What can transesophageal echocardiography confirm after a valve repair?

It allows the surgical team to assess the repair immediately - for example, checking for residual valve leakage and confirming ventricular function - while the patient is still in the operating room, and to verify removal of intracardiac air.