Key Points
- Transesophageal echocardiography (TEE) provides real-time, dynamic assessment of cardiac output (CO) and ventricular function, making it invaluable for intraoperative and critical care monitoring.
- CO can be estimated qualitatively and quantitatively via visual assessment of ventricular function and Doppler-derived stroke volume (SV), respectively.
- Key TEE views for CO assessment include mid-esophageal aortic valve long-axis (left ventricular outflow tract [LVOT] measurement), mid-esophageal four-chamber (global left ventricular and right ventricular function), and deep transgastric long axis (Doppler measurements of velocity-time integral through LVOT).
Introduction
- TEE utilizes an ultrasound probe inserted into the esophagus to provide a real-time assessment of cardiac function.
- TEE allows for quantitative and qualitative evaluation of CO.
Indications and Contraindications1
Indications
- Open-heart and thoracic aorta surgical procedures
- Catheter guidance in catheter-based intracardiac procedures
- Noncardiac surgery in patients with high-risk cardiac pathology
- Hemodynamic instability or unexplained hypotension
Contraindications
Table 1. Absolute and relative contraindications to transesophageal echocardiography.
Abbreviation: GI, gastrointestinal
Methods for Determining CO via TEE2
Qualitative Methods
- Visual estimation of ventricular contractility and wall motion, left ventricular end-diastolic area (evaluation of preload), left ventricular end-systolic area (evaluation of contractility)
- Limitations: subjective, operator-dependent, less reproducible
Figure 1 (LEFT). Mid-esophageal 4-Chamber transesophageal echocardiography view; Figure 2 (RIGHT). Transgastric Short Axis transesophageal echocardiography view
Quantitative Methods
- Doppler method: CO = CSALVOT x VTILVOT x heart rate (HR)
- CSA (Cross-Sectional Area) = π(Diameter/2)2
- VTI (Velocity-Time Integral) obtained via tracing pulsed wave Doppler profile through the LVOT in the deep transgastric long axis view.
Figure 3 (LEFT). Mid-esophageal aortic valve long-axis transesophageal echocardiography view; Figure 4 (RIGHT). Deep transgastric long-axis transesophageal echocardiography view
- Simpson’s Biplane Method
- Provides end-diastolic volume (EDV) and end-systolic volume (ESV), allowing the calculation of SV
- SV = EDV – ESV
- CO = SV x HR
- Provides end-diastolic volume (EDV) and end-systolic volume (ESV), allowing the calculation of SV
- Limitations: operator and angle dependent, assumes circular LVOT, and inaccurate LVOT measurements are magnified
Figure 5. Mid-esophageal 4-chamber transesophageal echocardiography view with Simpson’s biplane method.
Relevant TEE Views for CO Assessment
Table 2. Key transesophageal echocardiography images required for both quantitative and qualitative cardiac output assessment
Clinical Applications
- Monitoring CO in real-time enables guidance for fluid therapy, titration of inotropes, and the need for mechanical support.
- Together with additional hemodynamic parameters (e.g., mean arterial pressure, central venous pressure, pulmonary arterial pressure, systemic vascular resistance, and pulmonary vascular resistance), a more comprehensive hemodynamic picture can be created.
References
- Shanewise J. Transesophageal echocardiography. In: Gravelee G., Shaw A., Bartels K. Hensley’s Practical Approach to Cardiothoracic Anesthesia. Sixth Edition. China; Wolters Kluwer; 2019: 173
- Gillam L, Konstantinos K, Marcoff L. Assessment of left ventricular systolic function. In: Mathew J., Ayoub C., Nicoara A., Swaminathan M. Clinical Manual and Review of Transesophageal Echocardiography. Third Edition. China. McGraw-Hill Education. 2019. 161-162.
Other References
- Perkins H, Chatterjee D. Cardiac output monitoring in Anesthesia and Critical Care. 2025. Link
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