الفهرس 
Basic Principles and TechniquesOnly 14 pages are availabe for public view
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Abstract
The introduction of echocardiography into clinical practice represents one of the most important medical achievements. Transesophageal echocardiography (TEE) as an imaging technique in intra-operative patient monitoring provides dramatic non invasive imaging of the heart and great vessels as well as permitting quantification of blood flow and over all cardiac performance without interrupting the surgical procedure.
TEE is a special ultrasound monitor that uses sound waves to take pictures of the heart. Ultrasound creates its imaging by emitting high frequency acoustic pulses and allowing these pulses to travel through soft tissue, various tissues possess different acoustic properties and each interface causes a small portion of pulse energy to be reflected as an echo.
The M-mode allows time motion study of intracardiac structures with high resolution, the 2D display is a conventional anatomical tomography of the structures with a field up to 90° with increasing power of computers, its possible to reconstruct a three dimensional (3D) image of the heart structures.
TEE plays an important role in management of cardiac surgeries, vascular surgeries, and non cardiac surgeries in haemodynamically unstable patients.
TEE is better than ECG for detection of myocardial ischemia within seconds of regional myocardial oxygen deprivation as it can discovers it before or even in the absence of ECG changes.
Global left ventricular (LV) function is an important predictor of outcome in patients undergoing major surgeries. The simplest echocardiographic method for evaluating global LV function involves indirect measures of ejection fraction (EF).
TEE can be used to evaluate cardiac output and its individual component, right ventricular function and ventricular dysfunction associated with pulmonary embolism and thoracic aortic dissections (98% to 100%) is comparable to MRI and superior to CT or aortography as a screening test.
TEE is a particularly useful technique for diagnosing the presence and location of thrombus in all cardiac chambers with the exception of the LV, thrombus in the LV apex may be difficult to visualize via TEE approach compared to TTE.
Images of cardiac masses obtained by TEE are usually clearer, more defined, and often quite dramatic, TEE delineation of the extension and origination of intra and pericardial tumors can have major impact in determining the extent of the surgery.
TEE proved to be helpful for detecting and removing intra cardiac air to prevent an occurrence of embolic events as the retained air shows unique TEE findings.
TEE has proven itself to be a major diagnostic modality in the evaluation of patients of all ages with congenital heart disease. The lesion may be well defined preoperatively; a comprehensive TEE examination must confirm not only the presence of the known congenital lesion but also the nature and degree of this lesion, also the direction and quantification of shunting. In addition, it is important for the ultrasonographer to rule out the presence of collateral pathology.
TEE is evolving as a peri-operative monitoring and diagnostic tool in the intensive care unit, especially for the treatment of high-risk cardiovascular patients. Its significance lies in that it is the only direct method for imaging and evaluating heart function, calculation of ventricular volumes and ejection fraction of the left ventricle, evaluation of contractility and assessment of valvular anatomy and function, this is of particular importance in haemodynamically compromised patients; when an efficient, relatively safe and fast approach is required.
Although TEE is considered a noninvasive diagnostic and monitoring tool, it is not free from complications ranging from minor to life threatening. The overall morbidity is 0.2%, whereas mortality is around 0 – 0.004%, the complications may be divided according to system affected into cardiopulmonary, gastrointestinal and others.
from this essay we concluded that peri-operative Transesophageal Echocardiography (TEE) is a very useful monitor and should be a routine monitor in cardiac surgeries, also there should be adequate training of the anesthesiologist for proper use of the TEE