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| Views of the Aorta |
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As the aorta traverses from anterior to posterior, the arch deviates towards the left. The esophagus is posterior and slightly left of the ascending aorta and posterior to the aortic arch. The descending aorta then travels from anterior to posterior to a point in the diaphragm where the aorta is posterior to the esophagus.
The Society of Cardiovascular Anesthesiologists (SCA) and American Society of Echocardiography (ASE) have defined six views of the thoracic aorta that should be performed in the standard exam. The six views are listed below. Besides the six standard views, the aortic valve long and short axis views can be added because they include the aortic root which should be evaluated in every exam.
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| Midesophageal Aortic Valve Short Axis (ME AV SAX) |
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| The entire intrathoracic aorta can be evaluated from the midesophageal and upper esophageal acoustic windows. The aorta can be visualized in its short and/or long axis. Analysis usually starts with the aortic annulus and the sinuses of valsalva. Placing the transesophageal probe to the midesophageal window (30-40 cm) at the level of the aortic valve, the electronic plane is rotated to 30-45 degrees until the short axis of the aortic valve is optimized. In this view, the midesophageal aortic valve short axis view includes the sinuses of Valsalva and the aortic cusps. The cusps are named for the normal coronary artery origin. The right coronary cusp is the distal most sinus of Valsalva and is congruent with the right atrium, right ventricle and pulmonary artery. The left coronary cusp is congruent with the left atrium. The non-coronary cusp in congruent with the left atrium, right atrium and the interatrial septum. The normal cusps are of similar size and each contains an aortic valve leaflet that almost contacts the wall of the cusps. |
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| Midesophageal AV SAX Image |
Midesophageal AV SAX Video |
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| Midesophageal Aortic Valve Long Axis (ME AV LAX) |
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| Rotating the multiplane angle to 120 degrees where the aortic valve leaflets are maximal and the long axis of the ascending aorta is present is called the midesophageal aortic valve long axis view. From this view the geometry of the aortic root can be analyzed. The diameters of the LVOT, aortic annulus, sinus of valsalva, sinotubular junction, and the proximal ascending aorta can be measured and compared. The first 5-10 cm of the ascending aorta is typically visualized. |
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| Midesophageal AV LAX Image |
Midesophageal AV LAX Video |
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| Midesophageal Ascending Aorta Long Axis View (ME AscAo LAX) |
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| While the midesophageal aortic valve long axis may allow visualization of a significant portion of the ascending aorta, frequently, the aorta is ectatic or off angle to allow the complete visualization of the entire ascending aorta. Rotating the probe to 90-110 degrees and slightly withdrawing the probe to above the aortic valve (25 cm depth) will frequently yield up to a 10 cm view of the ascending aorta. From this view the most distal portion of the ascending aorta can be visualized until the aorta extends in front of the right bronchus where it becomes obscured from the esophageal acoustic windows. About 80% of the ascending aorta can be visualized, but in some patients only 40% is available for interrogation. Epiaortic scanning is required to view the portion of the ascending aorta that is not available from transesophageal echocardiography acoustic windows. This view is useful for determining the relative diameter of the ascending aorta, the wall thickness, aortic contour, aortic diameter, and blood flow patterns. |
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| Midesophageal Ascending Aorta LAX Image |
Midesophageal Ascending Aorta LAX Video |
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| Midesophageal Ascending Aorta Short Axis View (ME AscAo SAX) |
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| From the midesophageal long axis view the electronic plane is rotated to 0 degrees. The ascending aorta can be visualized by advancing/withdrawing the probe along the ascending aorta. slight anteflexion may be required for optimal contact. The advantage of the short axis view is the whole circumference of the ascending aorta is viewed whereas the long axis view only cuts through one plane of the ascending aorta. Small areas of focal disease may be missed in long axis views. The aortic wall thickness and diameter of the aorta can be determined. The superior vena cava and the right pulmonary and main pulmonary artery can be visualized. Proper placement of a pulmonary artery catheter can be documented. As the probe nears the left bronchus the visualization of the ascending aorta becomes suboptimal. |
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| Midesophageal AscAo SAX Image |
Midesophageal AscAo SAX Video |
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| Descending Aorta Short Axis View (DescAo SAX) |
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| From the midesophageal ascending aorta short axis view the transesophageal probe is rotated counter clockwise and the depth adjusted to 6-8 cm until the descending aorta is visualized. The frequency is increased to the highest setting to improve resolution. The probe is then advanced as far as possible while keeping the descending aorta in the screen center, rotating left or right during the advancement of the probe. Ectatic aortas may require significant manipulation and/or electronic angle adjustment from 0 degrees to view the short axis of the descending aorta. Once at the distal descending aorta the probe is slowly withdrawn to the aortic arch. Once at the junction of the aortic arch and descending aorta, the left subclavian may be visible. The short axis view allows the determination of the aortic diameter, wall thickness, periaortic hematomas and/or dissection, thrombus, arteriosclerosis, and aortic flow patterns. Left sided pleural effusions and/or pulmonary atelectasis can also be detected. |
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| The short axis of the descending aorta frequently exhibits a mirror artifact of the distal wall of the aorta. Between the distal wall and the mirrored wall, reverberation artifacts from calcium deposits in the aortic wall may be present. Color Doppler may also be present in the mirror artifact as well as pulse Doppler. Changing the view to a long axis will frequently, but not always, cause the artifact to disappear. Caution is recommended when a suspected diagnosis of aortic dissection is entertained. |
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| Descending Aorta SAX Image |
Descending Aorta SAX Video |
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| Descending Aorta Long Axis View (DescAo LAX) |
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| Starting at the junction of the distal aortic arch and descending aorta the probe is electronically rotated to 90 degrees. The left subclavian artery, if not visible at 0 degrees, may come into view. The probe is then advanced to the distal end of the descending aorta while keeping the descending aorta on the screen center. The long axis views are useful for determining flow patterns, branches, and the regularity/irregularity of the aortic wall. |
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| Descending Aorta LAX Image |
Descending Aorta LAX Video |
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| Upper Esophageal Aortic Arch Short Axis View (UE AoArch SAX) |
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| From the long axis view of the aortic arch, the probe is electronically rotated 70 to 90 degrees. The short axis view of the aortic arch and, if present, the innominate vein, is visualized. A branch of the aortic arch, the left carotid or left subclavian artery, can often be visualized. The long axis of the pulmonary artery may be present or can be visualized with rotating the probe clockwise. |
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| Upper Esophageal Aortic Arch SAX Image |
Upper Esophageal Aortic Arch SAX Video
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| Upper Esophageal Aortic Arch Long Axis View (UE AoArch LAX) |
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| Returning the probe to a multiplane angle of 0 degrees, and to the junction of the distal aortic arch and descending aorta, the probe is slowly withdrawn, rotated clockwise, and flexed to view the long axis of the aortic arch. The probe may need to be rotated clockwise and counter clockwise to view the great vessels. From a true long axis, the innominate vein may be present. Color doppler should allow one to discriminate whether a dissection of an innominate vein is present. If Doppler persists, a bubble study into a left arm vein will make the diagnosis. The long axis view is useful for determining branch vessels, wall contour, and dimensions. |
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| Upper Esophageal Aortic Arch LAX Image |
Upper Esophageal Aortic Arch LAX Video |
Upper Esophageal Aortic Arch SAX Video |
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| Epiaortic Views |
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| Epiaortic scanning with a linear array probe is useful in viewing those segments that are not optimally visulaized with transesophageal scanning. The epiaortic probe is placed on the ascending aorta where the aortic dimensions, wall thickness, wall contour, and aortic root morphology as well as the aortic valve can be viewed. Epiaortic scanning is a useful adjunct to transesophageal scanning. The scanning depth should be optimized and a standoff with water or saline in a sterile bag should be performed to improve the resolution of the scan. |
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Midesophageal AscAo SAX Image
Epiaortic Scan |
Midesophageal AscAo SAX Video
Epiaortic Scan |
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Midesophageal AscAo LAX Image
Epiaortic Scan |
Midesophageal AscAo LAX Video
Epiaortic Scan |
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Midesophageal AVLAX Image
Epiaortic Scan |
Midesophageal AVLAX Video
Epiaortic Scan |
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