Atlas of Transesophageal Echocardiography, 2nd Edition (2007)

Chapter 11. Transpharyngeal/Upper Transesophageal Examination

With the transesophageal probe positioned in the upper esophagus, the aortic arch and the proximal extent of its branches can be comprehensively examined in most patients. Longitudinal plane examination (90°) with clockwise rotation at the level of the aortic arch brings the origin of the innominate artery into view. This vessel can be followed in its proximal extent but the bifurcation cannot be imaged in most instances because of interference from the tracheobronchial tree. Counterclockwise rotation identifies the origin of the left common carotid artery and then, with further rotation, the left subclavian artery. If no branches are visualized using this maneuver, the probe is gradually withdrawn, carefully rotating it to detect these vessels. It is important to keep the color Doppler turned on during this procedure as color flow signals are useful in differentiating these vascular structures from the surrounding soft tissue. The left subclavian artery courses anteriorly and Doppler investigation reveals high resistance velocity waveforms with antegrade flow in systole and retrograde flow in diastole. The left subclavian artery gives rise to a number of branches, the most important of which are the left vertebral and left internal mammary arteries. These vessels usually arise opposite each other, generally at the point where the subclavian artery turns to course anteriorly. The internal mammary artery displays high resistance Doppler waveforms, whereas the vertebral artery shows low resistance signals characterized by prominent antegrade flow in both systole and diastole. Both vessels are smaller than the left subclavian artery. The left common carotid artery is generally about the same size as the subclavian artery, but displays low resistance Doppler signals, and none of its branches are visualized distinguishing it from the subclavian artery. Careful slow withdrawal of the probe, from the esophagus into the pharynx, while keeping the left common carotid artery in view, may demonstrate a slight dilatation (carotid bulb) before its bifurcation into the left internal and external carotid arteries. It is noteworthy to mention that the Doppler ultrasound beam can, in most instances, be aligned exactly parallel to flow direction in the internal carotid artery, permitting accurate assessment of velocities in the lumen of this vessel. This is in contrast to the surface approach where the Doppler beam is at a significant angle to the flow direction, which can result in marked underestimation of velocities, leading to erroneous diagnosis of stenosis severity. Both vessels show antegrade flow in systole and diastole, but generally the waveforms from the external carotid artery are sharper and the diastolic antegrade flow is less prominent. Also, the external carotid artery gives off branches that are easily visualized, whereas the internal carotid artery gives no branches in its extracranial course. If the intent is to examine right-sided neck vessels, then the probe, while in the upper esophagus, is rotated so that the face or footprint of the transducer is turned toward the right side of the patient. The probe is then gradually withdrawn and rotated slightly to identify vessels on the right side. Because of interference from the tracheobronchial tree, no vessels may be visualized for a few centimeters during probe withdrawal, but then one or more vessels appear while the probe is still in the esophagus. Doppler interrogation is then used to determine whether the vessel is the right subclavian or right common carotid artery. Similar to the right common carotid artery, the right vertebral artery will also demonstrate low resistance Doppler signals. However, this vessel is much smaller and its origin from the subclavian artery may be identified. In some patients, the right common carotid artery is the only vessel visualized when the probe is facing the right side of the patient. Further withdrawal of the probe into the pharynx will demonstrate its bifurcation into right internal and external carotid arteries. Here also, it is easy to align the Doppler ultrasound beam parallel to the flow direction in the internal carotid artery. Throughout this examination, with the probe positioned in both the upper esophagus and the pharynx, veins of different caliber are noted adjacent to these arteries. These are easily differentiated by their typical nonpulsatile continuous Doppler flow signals throughout the cardiac cycle. Because of the collapsed nature of the esophagus, the probe is in close contact with the esophageal wall when it is rotated to examine the vessels on both the left and right sides of the patient. However, once the probe has been withdrawn into the pharynx, which is a considerably larger cavity, contact may be lost, making it impossible to see the vessels. The probe will then need to be physically moved to the opposite side for contact with the pharyngeal wall or reinserted into the esophagus, rotated appropriately to the opposite side of the neck, and withdrawn into the pharynx, taking care to maintain contact with the pharyngeal wall. Another alternative is to physically place the probe in the tonsillar fossa either before commencing the transesophageal examination or after completion of the procedure. The carotid artery can be palpitated in the tonsillar fossa and the probe placed directly over it. An important prerequisite for this procedure is adequate topical anesthesia of the pharynx. Otherwise, patient gagging and tongue motion will dislodge the probe. The procedure is easier to perform in older patients without repeating topical anesthesia because many of them have a poor gag reflex. A major advantage of this procedure is examination and assessment of the neck vessels during transesophageal echocardiography without using another probe, and accurate assessment of vessel stenosis severity. In addition to assessing carotid artery stenoses, the technique has been used to detect the patency of stents placed in the internal carotid artery, carotid body ganglioma, distal extracranial segments of vertebral arteries, and reversed diastolic blood flow in the neck vessels in severe aortic regurgitation. Successful transpharyngeal examination depends, among other things, on patient anatomy and cooperation, and on operator experience.

FIGURE 11.1. Schematic representation of the oropharynx, laryngopharynx, and esophagus. CR, cricoid cartilage; EP, epiglottis; ES, esophagus; HY, hyoid bone; S, soft palate; THY, thyroid cartilage; TR, trachea; 1, nasopharynx; 2, oropharynx (from soft palate to hyoid bone); 3, laryngopharynx (from hyoid bone to esophagus); 4, level where the left common carotid artery (CA) bifurcates into external and internal CAs. This is generally at the upper end of the THY. (Reproduced with permission from 

Nanda NC, Biederman RW, Thakur AC, Nanda A, et al. Examination of left external and internal carotid arteries during transesophageal echocardiography. Echocardiography 1998;15:755–758.

)

FIGURE 11.2. Schematic demonstrating the technique of examining both the left- and right-sided carotid arteries. E, esophagus; IA, innominate artery; LCC, left common carotid artery; LEC, left external carotid artery; LIC, left internal carotid artery; LSA, left subclavian artery; P, probe; RCC, right common carotid artery; REC, right external carotid; RIC, right internal carotid; V, left internal jugular vein. (Reproduced with permission from 

Nanda NC, Miller AP, Nekkanti R, et al. Transpharyngeal echocardiographic imaging of the right and left carotid arteries. Echocardiography 2001;18:711–716.

)

FIGURE 11.3. Transpharyngeal ultrasound examination of left-sided carotid arteries. A. Arrowheads point to several branches of the left external carotid artery (LEC). B. The arrowhead points to the ascending pharyngeal branch of LEC. C. Color Doppler–guided pulsed-Doppler examination of the left internal carotid artery (LIC) (arrowhead) demonstrates prominent antegrade flow in systole and diastole, whereas in (D) interrogation of the LEC (arrowhead) demonstrates paucity of antegrade diastolic flow signals. Note the parallel alignment of the Doppler cursor line with flow direction in LIC in (C)E, esophagus; IA, innominate artery; LCC, left common carotid artery; L, longitudinal plane; P, probe; V, left internal jugular vein. (Reproduced with permission from 

Nanda NC, Miller AP, Nekkanti R, et al. Transpharyngeal echocardiographic imaging of the right and left carotid arteries. Echocardiography 2001;18:711–716.

)

FIGURE 11.4. Transpharyngeal ultrasound examination of right-sided carotid arteries. A,B. The right common carotid artery (RCC) bifurcates into right internal carotid (RIC) and right external carotid (REC) branches. C. Color Doppler–guided pulsed-Doppler interrogation of the RIC (arrowhead) shows prominent antegrade systolic and diastolic flow signals, whereas in (D), examination of the REC (arrowhead) shows much less prominent antegrade diastolic signals. Note the parallel alignment of the Doppler cursor line with flow direction in RIC in (C). E. Pulsed-Doppler interrogation of the right internal jugular vein (V) (arrowhead) demonstrates flow signals typical of venous flow. (Reproduced with permission from 

Nanda NC, Miller AP, Nekkanti R, et al. Transpharyngeal echocardiographic imaging of the right and left carotid arteries. Echocardiography 2001;18:711–716.

)

FIGURE 11.5. Upper transesophageal echocardiographic examination of the right subclavian artery. A,B. The right subclavian artery (RSA) is viewed in short (A) and long axis(B) views. Color Doppler–guided pulsed-Doppler interrogation demonstrates the typical high resistance flow pattern (inset). C. The right common carotid artery (RCC) comes into view as the probe is gradually withdrawn from the esophagus into the pharynx. E, esophagus; IA, innominate artery; LCC, left common carotid artery; L, longitudinal plane; P, probe; V, left internal jugular vein. (Reproduced with permission from 

Nanda NC, Miller AP, Nekkanti R, et al. Transpharyngeal echocardiographic imaging of the right and left carotid arteries. Echocardiography 2001;18:711–716.

)

FIGURE 11.6. Transpharyngeal ultrasound examination of right-sided carotid arteries. A. The right common carotid artery (RCC) can be seen in branching into the right external carotid artery (REC) and right internal carotid artery (RIC). B. The arrowhead points to a branch of the REC. Note the prominent carotid bulb (B) in B. (Reproduced with permission from 

Nanda NC, Miller AP, Nekkanti R, et al. Transpharyngeal echocardiographic imaging of the right and left carotid arteries. Echocardiography 2001;18:711–716.

)

FIGURE 11.7. Transpharyngeal ultrasound diagnosis of left carotid bulb and internal carotid artery stenosis. A,B. The arrowheads point to a prominent calcified plaque in the bulb and proximal portion of the left internal carotid artery (LIC). C. Color Doppler examination demonstrating the ascending pharyngeal (AP) and other branches (arrows) of the left external carotid artery (LEC). The left internal jugular vein (LIJV) is seen adjacent to the left common carotid artery (LCC). D,E. Color Doppler–guided pulsed and continuous-wave Doppler examination of the proximal LIC shows a peak systolic velocity of 1.8 m/s and a peak diastolic velocity approaching 1.0 m/s, indicative of significant stenosis. Note that the Doppler beam is aligned parallel to the flow direction in the proximal LIC. F. Pulsed-Doppler interrogation of the LIJV demonstrates continuous venous-type flow signals throughout the cardiac cycle. G. The arrow shows a large atherosclerotic plaque at the origin of the left subclavian artery (LSA). The probe was in the upper esophagus. AO, aorta. (Reproduced with permission from 

Nanda NC, Miller AP, Nekkanti R, et al. Transpharyngeal echocardiographic imaging of the right and left carotid arteries. Echocardiography 2001;18:711–716.

)

FIGURE 11.8. Transpharyngeal ultrasound detection of a left carotid stent. A,B. Arrowheads point to the stent in the distal left common carotid (LCC) and proximal left internal carotid (LIC) arteries. Stent is identified by its serrated appearance. C. Color Doppler–guided pulsed-Doppler interrogation of the LIC at the level of the stent shows normal systolic and diastolic flow velocities. (Reproduced with permission from 

Miller A, Nanda NC, Mukhtar O, et al. Transpharyngeal echocardiographic detection of a left internal carotid artery stent. Echocardiography 2000;17:739–741.

)

FIGURE 11.9. Transpharyngeal ultrasound detection of carotid body paraganglioma. A. The arrowheads show an encapsulated mass. B. The tumor mass (arrowheads) surrounds the distal right common carotid artery (CA). Color Doppler–guided pulsed-Doppler interrogation of CA (inset) demonstrates a high maximum systolic velocity of 1.5 m/sec and a high maximum diastolic velocity of 1.0 m/sec suggestive of tumor compression. C. Tumor vascularity is well seen. Note the Nyquist limit has been reduced to 7 cm/sec. (Reproduced with permission from 

Khanna D, Cheng PH, Nanda NC, et al. Transpharyngeal ultrasound detection of carotid body paraganglioma. Echocardiography 2004;21:299–301.

)

FIGURE 11.10. Transesophageal ultrasound demonstration of reversed pandiastolic flow in the aortic arch branches and neck vessels in severe aortic regurgitation due to aortic dissection. Probe in the upper esophagus. A,B. Color Doppler–guided continuous-wave Doppler examination of the left subclavian (SA, A) and left vertebral arteries (VA,B) demonstrates pandiastolic backflow (arrowhead in the inset) in both vessels. The arrows in the inset in B point to less dense and less prominent Doppler signals and these represent artifacts due to a mirroring phenomenon. (Reproduced with permission from 

Khanna D, Sinha A, Nanda NC, et al. Transesophageal and transpharyngeal ultrasound demonstration of reversed diastolic flow in aortic arch branches and neck vessels in severe aortic regurgitation. Echocardiography 2004;21:349–353.

)

FIGURE 11.11. Transpharyngeal ultrasound demonstration of reversed diastolic flow in neck vessels in severe aortic regurgitation due to aortic dissection. A,B. Probe in the left pharynx. Color Doppler–guided continuous-wave Doppler examination of the left common carotid artery (CA, A) near the carotid bulb, and color Doppler–guided pulsed-wave Doppler examination of the proximal left internal CA (B) demonstrate pandiastolic backflow in both neck vessels (arrowhead in both insets). (Reproduced with permission from 

Khanna D, Sinha A, Nanda NC, et al. Transesophageal and transpharyngeal ultrasound demonstration of reversed diastolic flow in aortic arch branches and neck vessels in severe aortic regurgitation. Echocardiography 2004;21:349–353.

)

FIGURE 11.12. Transesophageal and transpharyngeal echocardiographic detection of the extracranial segments of the left vertebral artery (LVA). A. Shows the precervical segment (V1) of the LVA, (arrows) originating from the left subclavian artery (LSA) and coursing toward the foramen of C6 vertebral body (arrowhead). B. Shows the cervical segment (V2) of the LVA (arrows) interposed by echo void areas resulting from “shadowing” produced by the bony vertebral bodies C6-C1 (arrowheads). (Reproduced with permission from 

Zoghbi GJ, Nanda NC, Baweja G. Transesophageal and transpharyngeal echocardiographic detection of the extracranial segments of the left vertebral artery. Am J Geriatr Cardiol 2003;12:113–116.

)

FIGURE 11.13. Transesophageal and transpharyngeal echocardiographic detection of the extracranial segments of the left vertebral artery (LVA). Schematic showing all four segments (V1–V4) of the LVA. ACH, aortic arch; C1-C6, cervical vertebrae; E, left external carotid artery; I, left internal carotid artery; LCC, left common carotid artery;LIMA, left internal mammary artery; LSA, left subclavian artery. (Reproduced with permission from 

Zoghbi GJ, Nanda NC, Baweja G. Transesophageal and transpharyngeal echocardiographic detection of the extracranial segments of the left vertebral artery. Am J Geriatr Cardiol 2003;12:113–116.

)

 

Suggested Readings

Howard JH, Dod HS, Nanda NC, et al. Transpharyngeal ultrasound evaluation of internal carotid artery stent in an octogenarian. Am J Geriatr Cardiol 2003;12:375–376.

Khanna D, Cheng PH, Nanda NC, et al. Transpharyngeal ultrasound detection of carotid body paraganglioma. Echocardiography 2004;21:299–301.

Khanna D, Sinha A, Nanda NC, et al. Transesophageal and transpharyngeal ultrasound demonstration of reversed diastolic flow in aortic arch branches and neck vessels in severe aortic regurgitation. Echocardiography 2004;21:349–353.

Miller AP, Aaluri SR, Mukhtar OM, et al. Three-dimensional color Doppler transpharyngeal echocardiographic reconstruction of the left common, internal and external carotid arteries. Echocardiography 2002;19:223–225.

Miller A, Nanda NC, Mukhtar O, et al. Transpharyngeal echocardiographic detection of a left internal carotid artery stent. Echocardiography 2000;17:739–741.

Nanda NC, Biederman RW, Thakur AC, Nanda A, et al. Examination of left external and internal carotid arteries during transesophageal echocardiography. Echocardiography 1998;15:755–758.

Nanda NC, Gomez CR, Narayan VK, et al. Transpharyngeal echocardiographic diagnosis of carotid bulb and left internal carotid artery stenosis. Echocardiography 1999;16:671–674.

Nanda NC, Miller AP, Nekkanti R, et al. Transpharyngeal echocardiographic imaging of the right and left carotid arteries. Echocardiography 2001;18:711–716.

Nanda NC, Thakur AC, Thakur D, et al. Transesophageal echocardiographic examination of left subclavian artery branches. Echocardiography 1999;16:271–277.

Prakash YS, Malouf JF. Aberrant right common carotid artery: a diagnostic challenge on transesophageal echocardiography. Int J Cardiovasc Imaging 2004;20:217–219.

Zoghbi GJ, Nanda NC, Baweja G. Transesophageal and transpharyngeal echocardiographic detection of the extracranial segments of the left vertebral artery. Am J Geriatr Cardiol 2003;12:113–116.