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Over the past decade, the practice of perioperative transesophageal echocardiography (TEE) has evolved to the point that many anesthesiology departments own and operate their own ultrasound equipment and offer comprehensive perioperative TEE services, rather than “borrowing” equipment from cardiology colleagues or requesting their professional assistance in the operating room. The successful initiation and delivery of perioperative TEE services requires attention to a number of organizational details. First, practitioners with adequate training should be credentialed by the hospital for performance of perioperative TEE. Additionally, each program requires building a system for report generation and data storage, allocation of capital resources as well as skilled technical personnel to maintain and operate equipment, and implementation of a Continuous Quality Improvement (CQI) process. Finally, an efficient reimbursement infrastructure will ensure the program's fiscal viability. Although specific organizational details will depend on the individual institution and setting, the current chapter provides practical general guidelines that may be implemented to achieve success.
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The TEE probe in use today has changed little in concept from that originally introduced by Hisanaga in 1977.1 Most probes are a modified gastroscope with an ultrasound transducer mounted on the tip. They are 80 to 100-cm long with a shaft diameter of 10 mm, a tip width of 12 to 14 mm, and are latex-free. Newer three-dimensional (3D) probes are approximately 1 mm wider at the tip than existing two-dimensional (2D) probes. Rotary dials in the handheld housing control a series of cables sealed within the shaft that allow flexion and extension as well as side-to-side lateral bending of the tip. Range of motion of the tip varies slightly among manufacturers but is approximately 60° up and down as well as 60° to the right and left. Buttons on the side of the housing electronically steer the ultrasound transducer at the tip, providing full 180° rotation.
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A grounded shield covers all active circuits distal to the control housing, making electrical injury highly unlikely unless the outer layer of the shaft is cracked. However, the probe should always be disconnected prior to external defibrillation, as any minor defect in the covering could allow secondary arcing, potentially causing severe burns. Generally, the probe should be disconnected if left in place and unused for extended periods of time, such as during cardiopulmonary bypass, to prevent thermal injury or interaction with electrosurgical units. Electrical integrity of the TEE probe should be tested by a qualified technician as part of preventive maintenance, according to the manufacturer's protocol. This includes conducting frequent “bite hole” inspections as well as annual temperature calibration and current-leakage tests.
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Current ultrasound machines are equipped with safety features to minimize risks of injury to the patient. Units will “time out” after a designated period, often 10 minutes, of inactivity to avoid probe overheating. In addition, there is an auto-cool feature that will interrupt ultrasound transmission if the transducer becomes excessively hot. Current models will freeze scanning at 41°C, although this can ...