Transesophageal echocardiography safety

Numerous complications have been attributed to TEE use, including vocal cord paresis, dysphagia or odynophagia, inadvertent manipulation of the tracheal tube, bronchospasm, arrhythmias, and vascular compression during flexion of the probe tip, particularly in infants. Minor trauma to the hypopharynx is not an uncommon finding following probe insertion. In one study, fiberoptic examination revealed hypopharyngeal hematoma or laceration in 24% of adult patients after typical blind insertion of the TEE probe, although no patients required treatment of these iatrogenic injuries. Probe insertion with direct visualization probably reduces the rate of hypopharyngeal injury. More serious complications, such as esophageal perforation, although fortunately rare, may occur more often than previously believed. In a recent study of more than 15,000 intraoperative TEE examinations, investigators reported 6 gastric or esophageal tears and 8 esophageal perforations, yielding an overall serious complication rate of about 1 in 1000 intraoperative examinations. Another study identified 7 esophageal perforations in more than 22,000 TEE examinations; 3 of those 7 patients died, giving an overall mortality rate of 0.014%.

Anatomic correlations

Irrespective of the reason for the TEE study, a comprehensive examination is recommended for every patient, preferably before focusing on a specific question or application of TEE. It is beyond the scope of this brief description to detail all the anatomic views obtainable with TEE, and the reader is referred to other reviews of the subject.

Basic probe movements

To generate desired images, manipulation of the TEE probe is required in addition to changing the multiplane or biplane angle (Figure 53-1). The basic probe movements include insertion or withdrawal of the probe within the esophagus or stomach. Anteflexion and retroflexion of the probe tip are controlled with the large wheel on the probe and result in cephalad or caudad angulation of the imaging plane, respectively. Left-side and right-side flexion can be achieved by manipulating the smaller wheel on the probe and cause deflection of the probe tip within a coronal plane. Rotation of the probe refers to clockwise or counterclockwise spinning of the probe shaft.

Standard views

The American Society of Echocardiography and Society of Cardiovascular Anesthesiologists consensus task force defined the minimum recommended views that make up the standard intraoperative TEE examination. These standard views have been pictorially displayed, along with the associated icon depicting a typical multiplane angle at which the image may be generated, in Figure 53-2. It is important to remember that additional “off-axis” or nonstandard views may be required to adequately examine specific findings in any given patient. Furthermore, the multiplane angles suggested by the images should be considered a rough guide; the precise multiplane angle at which a given structure is best imaged varies among patients. A complete description of the probe maneuvers necessary to obtain these views is beyond the scope of this chapter. Readers are referred to the task force consensus statement.

When studying the images that make up the comprehensive multiplane intraoperative TEE examination, the use of several tips may prove helpful. First, in the majority of the midesophageal (ME) images, the structure closest to the probe (that is, the chamber at the apex of the image) is the left atrium. The only exception is when the probe is withdrawn above the left atrium and resides directly behind the great vessels. In this superior position, the probe is nearest the right pulmonary artery, which can be seen in long-axis (LAX) view, along with the pulmonary artery bifurcation in the ME ascending aortic short-axis (SAX) view. Increasing the multiplane angle by approximately 90 degrees yields the ME ascending aortic LAX view, in which the right pulmonary artery is seen in SAX view. These two views demonstrate the orthogonal relationship between the ascending aorta and the right pulmonary artery. (The aortic and pulmonary valves also have a near-orthogonal relationship.) Second, the transgastric (TG) LAX views are most useful for placing a Doppler cursor in near-parallel alignment with the left ventricular outflow tract and aortic root. In this position, an aortic valve or left ventricular outflow tract velocity may be measured and used to calculate a pressure gradient across the aortic valve. Third, TG SAX views of the left ventricle, such as the TG midpapillary SAX views, are often selected when monitoring for ischemia, as myocardium perfused by the three major coronary arteries can be visualized in a single image. Ideally, regional wall motion abnormalities identified in the TG mid-SAX view are confirmed in other views, such as the ME four-chamber, two-chamber, or LAX planes.