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ASE/SCA Guidelines for Performing a Comprehensive Intraoperative Multiplane Transesophageal Echocardiography Examination: Recommendations of the American Society of Echocardiography Council for Intraoperative Echocardiography and the Society of Cardiovascular Anesthesiologists Task Force for Certification in Perioperative Transesophageal Echocardiography

1999; Lippincott Williams & Wilkins; Volume: 89; Issue: 4 Linguagem: Inglês

10.1097/00000539-199910000-00010

1526-7598

Jack S. Shanewise, Albert T. Cheung, Solomon Aronson, William J. Stewart, Richard L. Weiss, Jonathan B. Mark, Robert Savage, Pamela Sears-Rogan, Joseph P. Mathew, Miguel A. Quiñones, Michael K. Cahalan, Joseph S. Savino,

Cardiac Imaging and Diagnostics

Since the introduction of transesophageal echocardiography (TEE) to the operating room in the early 1980s (1,3,4), 1 its effectiveness as a clinical monitor to assist in the hemodynamic management of patients during general anesthesia and its reliability to make intraoperative diagnoses during cardiac operations has been well established (5–26). In recognition of the increasing clinical applications and use of intraoperative TEE, the American Society of Echocardiography (ASE) established the Council for Intraoperative Echocardiography in 1993 to address issues related to the use of echocardiography in the operating room. In June 1997, the Council board decided to create a set of guidelines for performing a comprehensive TEE examination composed of a set of anatomically directed cross-sectional views. The Society of Cardiovascular Anesthesiologists Task Force for Certification in Perioperative Transesophageal Echocardiography has endorsed these guidelines and standards of nomenclature for the various anatomically directed cross-sectional views of the comprehensive TEE examination. This document, therefore, is the collective result of an effort that represents the consensus view of both anesthesiologists and cardiologists who have extensive experience in intraoperative echocardiography. The writing group has several goals in mind in creating these guidelines. The first is to facilitate training in intraoperative TEE by providing a framework in which to develop the necessary knowledge and skills. The guidelines may also enhance quality improvement by providing a means to assess the technical quality and completeness of individual studies. More consistent acquisition and description of intraoperative echocardiographic data will facilitate communication between centers and provide a basis for multicenter investigations. In recognition of the increasing availability and advantages of digital image storage, the guidelines define a set of cross-sectional views and nomenclature that constitute a comprehensive intraoperative TEE examination that could be stored in a digital format. These guidelines will encourage the industry to develop echocardiography systems that allow the quick and easy acquisition, labeling, and storage of images in the operating room, as well as a simple mechanism for side-by-side comparison of views made at different times. The following discussion is limited to a description of a method to perform a comprehensive intraoperative echocardiographic examination and does not address specific diagnoses, which is beyond the scope of a journal article. It describes how to examine a patient with “normal” cardiac structures to establish a baseline for later comparison. A systematic and complete approach ensures that unanticipated or clinically important findings will not be overlooked. Routinely performing a comprehensive examination also increases the ability to recognize normal structures and distinguish normal variants from pathologic states, thereby broadening experience and knowledge more rapidly. The description of the examination in the guidelines is based on multiple imaging plane (multiplane) TEE technology because it represents the current state of the art and is the type of system most commonly used. Compared with single plane or biplane imaging, multiplane TEE provides the echocardiographer with a greater ability to obtain images of cross-sections with improved anatomic orientation to the structures being examined (27–31). The writing group recognizes that individual patient characteristics, anatomic variations, pathologic features, or time constraints imposed on performing the TEE examination may limit the ability to perform every aspect of the comprehensive examination. Whereas the beginner should seek a balance between a fastidiously complete, comprehensive examination and expedience, an experienced echocardiographer can complete the recommended examination in 30% thickening), 2 = mildly hypokinetic (10% to 30% thickening), 3 = severely hypokinetic (<10% thickening), 4 = akinetic (does not thicken), 5 = dyskinetic (moves paradoxically during systole). This grading scale has been used extensively in the intraoperative echocardiography literature (5,7,41–55). All 16 segments are examined by obtaining five cross-sectional views of the LV, three through the mid esophageal window and two through the transgastric window. Figure 4: 16-segment model of the left ventricle. a, Four-chamber views show the three septal and three lateral segments. b, Two-chamber views show the three anterior and three inferior segments. c, Long axis views show the two anteroseptal and two posterior segments. d, Mid short axis views show all six segments at the mid level. e, Basal short axis views show all six segments at the basal level.Figure 5: Typical regions of myocardium perfused by each of the major coronary arteries to the left ventricle. Other patterns occur as a result of normal anatomic variations or coronary disease with collateral flow. LAD = left anterior descending, Cx = circumflex, RCA = right coronary artery.To obtain the mid esophageal views of the LV, the transducer is positioned posterior to the LA at the mid level of the MV. The imaging plane is then oriented to pass simultaneously through the center of the mitral annulus and the apex of the LV. The LV is usually oriented within the patient’s chest, with its apex somewhat more inferior than the base, so the tip of the probe may require retroflexion to direct the imaging plane through the apex. The depth is adjusted to include the entire LV, usually 16 cm. The mid esophageal four-chamber view (Figure 3A) is now obtained by rotating the multiplane angle forward from 0 degrees to between 10 and 20 degrees, until the AV is no longer in view and the diameter of the tricuspid annulus is maximized. The mid esophageal four-chamber view shows the basal, mid, and apical segments in each of the septal and lateral walls (Figure 4A). The mid esophageal two-chamber view (Figure 3B) is developed by rotating the multiplane angle forward to between 80 and 100 degrees until the right atrium (RA) and right ventricle (RV) disappear. This cross-section shows the basal, mid, and apical segments in each of the anterior and inferior walls (Figure 4B). Finally, the mid esophageal long axis view (Figure 3C) is developed by rotating the multiplane angle forward to between 120 and 160 degrees, until the LV outflow tract (LVOT), AV, and the proximal ascending aorta come into view. This view shows the basal and mid anteroseptal segments, as well as the basal and mid posterior segments (Figure 4C). With the imaging plane properly oriented through the center of the mitral annulus and the LV apex, the entire LV can be examined, without moving the probe, by simply rotating forward from 0 to 180 degrees. Figure 6 illustrates how the mid esophageal views transect the LV. It can be difficult to image the apex of the LV with TEE in some patients, especially if the LV is enlarged or has an apical aneurysm. Figure 6: Short axis drawing of the left ventricle at the mid papillary level illustrating how it is transected by the mid esophageal views. Rotating from multiplane angle 0 degrees to 180 degrees moves the imaging plane axially through the entire left ventricle. ME = mid esophageal.The transgastric views of the LV are acquired by advancing the probe into the stomach and anteflexing the tip, until the heart comes into view. At a multiplane angle of 0 degrees, a short axis view of the LV will appear, and the probe is then turned to the right or left as needed to center the LV in the display. The image depth is adjusted to include the entire LV, usually 12 cm. Next, the multiplane angle is rotated forward to 90 degrees to show the LV in long axis with the apex to the left and the mitral annulus to the right of the display. The anteflexion of the probe is adjusted until the long axis of the LV is horizontal in the display (Figure 3E). The level of the LV over which the transducer lies is noted (basal, mid, or apical), and the probe is advanced or withdrawn as needed to reach the mid papillary level. Now, the multiplane angle is rotated back to between 0 and 20 degrees, until the circular symmetry of the chamber is maximized to obtain the transgastric mid short axis view (Figure 3d). This cross-section shows the six mid level segments of the LV and has the advantage of simultaneously showing portions of the LV supplied by the right, circumflex, and left anterior descending coronary arteries and is the most popular view for monitoring LV function (Figure 5). The transgastric mid short axis view is used for assessing LV chamber size and wall thickness at end diastole, which is best determined by measuring at the onset of the R wave of the electrocardiogram. Normal LV short axis diameter is less than 5.5 cm, and LV wall thickness is less than 1.2 cm. End diastolic and end systolic areas of the LV chamber may be measured in this cross-section for calculation of fractional area change as an index of LV systolic function. The transgastric two-chamber view (Figure 3E) is developed by rotating the multiplane angle forward to approximately 90 degrees, until the apex and the mitral annulus come into view. The probe is turned to the left or right as needed to maximize the length of the LV chamber in the image. This view shows the basal and mid segments of the inferior and anterior walls, but usually not the apex. The transgastric basal short axis view (Figure 3F) is obtained by withdrawing the probe from the transgastric mid short axis view until the MV appears. It shows all six basal segments of the LV. When advancing or withdrawing the probe to different ventricular levels, it is helpful to do so from the transgastric two-chamber view, which shows the position of the transducer in relation to the long axis of the LV. When the desired level is reached, the short axis view is obtained by rotating the multiplane angle back toward 0 degrees. Mitral Valve The MV is composed of the anterior and posterior leaflets, chordae tendinae, papillary muscles, annulus, and LV walls. The two leaflets are joined at the anterolateral and posteromedial commissures, each of which is associated with a corresponding papillary muscle. The posterior leaflet consists of three scallops: lateral (P1), middle (P2), and medial (P3). For descriptive purposes, the anterior leaflet is divided into three parts: lateral third (A1), middle third (A2), and medial third (A3) (Figure 7). Figure 7: Anatomy of the mitral valve. A1 = lateral third of the anterior leaflet, A2 = middle third of the anterior leaflet, A3 = medial third of the anterior leaflet, P1 = lateral scallop of the posterior leaflet, P2 = middle scallop of the posterior leaflet, P3 = medial scallop of the posterior leaflet.The MV is examined with TEE by using four mid esophageal and two transgastric views. The mid esophageal views of the MV are all developed by first positioning the transducer posterior to the mid level of the LA and directing the imaging plane through the mitral annulus parallel to the transmitral flow. Again, because the apex of the LV is located inferior to the base of the heart in many patients, retroflexion of the probe tip is often necessary. The multiplane angle is then rotated forward to develop the mid esophageal four chamber view. In this cross-section, the posterior mitral leaflet P1 is to the right of the image display, and the anterior mitral leaflet A3 is to the left. As the multiplane angle is rotated forward to about 60 degrees, a transition in the image occurs beyond which the posterior leaflet is to the left of the display, and the anterior leaflet is to the right. At this transition angle, the imaging plane is parallel to the line that intersects the two commissures of the MV, to form the mid esophageal mitral commissural view (Figure 3G). In this view, A2 is seen in the middle of the LV inflow tract with the posterior leaflet on each side; P1 is to the right of the display, and P3 is to the left. Beginning from a point where the imaging plane transects the middle of the valve, turning the probe to the right moves the plane toward the medial side of the MV through the base of the anterior leaflet, whereas turning the probe to the left moves the plane toward the lateral side through P2 of the posterior leaflet. Next, the multiplane angle is rotated forward to develop the mid esophageal two-chamber view. Now the posterior leaflet (P3) is to the left of the display and the anterior leaflet (A1) is to the right. Finally, the multiplane angle is rotated forward to the mid esophageal long axis view. In this view, the posterior mitral leaflet (P2) is to the left of the display, and the anterior mitral leaflet (A2) is to the right. As with the LV, proper orientation of the imaging plane from the mid esophageal window through the center of the mitral annulus permits the entire MV to be examined without moving the probe by rotating forward from 0 to 180 degrees, and both structures are easily examined simultaneously. Figure 8 illustrates how the mid esophageal views transect the MV. Figure 8: Short axis drawing of the mitral valve illustrating how it is transected by the mid esophageal views. Rotating from multiplane angle from 0 degrees to 180 degrees moves the imaging plane axially through the entire mitral valve. ME = mid esophageal.The mid esophageal views of the MV are repeated with CFD, ensuring that the color sector includes the left atrial portion of any mitral regurgitation jet as well as the ventricular aspect of the valve to detect any flow convergence caused by mitral regurgitation. This is easily accomplished by rotating the multiplane angle backward from the mid esophageal long axis view through the two-chamber, mitral commissural and four-chamber views. The transmitral flow velocity profile is examined using spectral pulsed wave Doppler (PWD) to evaluate LV diastolic function in the mid esophageal four-chamber or mid esophageal long axis view by placing the sample volume between the tips of the open mitral leaflets. The sample volume size is kept as small as possible (3–5 mm) and the Doppler beam aligned such that the angle between the beam and the presumed direction of transmitral flow is as close to zero as possible. The two transgastric views of the MV are developed by advancing the probe until the transducer is level with the base of the LV. The transgastric basal short axis view provides a short axis view of the MV and is generally obtained at a multiplane angle of 0 degrees by further anteflexing the probe and withdrawing slightly to achieve a plane slightly above (superior to) the transgastric mid short axis view. Better short axis cross-sections of the MV often are obtained with the transducer slightly deeper in the stomach and with more anteflexion in order to orient the imaging plane as parallel to the mitral annulus as possible. Often, however, the cross-section obtained is not perfectly parallel to the annulus, in which case the probe is withdrawn to image the posteromedial commissure in short axis, then advanced slightly to image the anterolateral commissure. In these views of the MV, the posteromedial commissure is in the upper left of the display, the anterolateral commissure is to the lower right, the posterior leaflet is to the right of the display, and the anterior leaflet is to the left. These short axis views of the MV are very useful for determining which portion of the leaflet is abnormal or has abnormal flow. It is also important to examine the transgastric mid short axis view to detect wall motion abnormalities adjacent to the papillary muscles or hypermobility at the papillary muscles indicating rupture of the papillary muscle or its components. The transgastric two-chamber view is developed from the same probe position by rotating the multiplane angle forward to about 90 degrees and is especially useful for examining the chordae tendinae, which are perpendicular to the ultrasound beam in this view. The chordae to the posteromedial papillary muscle are at the top of the display, and those to the anterolateral papillary muscle are at the bottom. Both of the transgastric views of the MV are repeated using CFD. Aortic Valve, Aortic Root, and Left Ventricular Outflow Tract The AV is a semilunar valve with three cusps located close to the center of the heart. The aortic root is not a specific structure, per se, but includes the AV annulus, cusps, sinuses of Valsalva, coronary artery ostia, sinotubular junction, and proximal ascending aorta. The LVOT is the outflow portion of the LV just inferior to the AV. All these structures are examined in detail with TEE by using four cross-sections. The mid esophageal AV short axis view (Figure 3h) is obtained from the mid esophageal window by advancing or withdrawing the probe until the AV comes into view and then turning the probe to center the AV in the display. The image depth is adjusted to between 10 and 12 cm to position the AV in the middle of the display. Next, the multiplane angle is rotated forward to approximately 30 to 60 degrees until a symmetrical image of all three cusps of the aortic valve comes into view. This cross-section is the only view that provides a simultaneous image of all three cusps of the AV. The cusp adjacent to the atrial septum is the noncoronary cusp, the most anterior cusp is the right coronary cusp, and the other is the left coronary cusp. The probe is withdrawn or anteflexed slightly to move the imaging plane superiorly through the sinuses of Valsalva to bring the right and left coronary ostia and then the sinotubular junction into view. The probe is then advanced to move the imaging plane through and then proximal to the AV annulus to produce a short axis view of the LVOT. The mid esophageal AV short axis view at the level of