1. Correct Answer: C. Transesophageal echocardiography (TEE) has a higher sensitivity for detection of endocarditis when evaluating replaced valves as compared to TTE.

Rationale: TEE has nearly 100% sensitivity for the detection of endocarditis involving both native and prosthetic valves. Though the sensitivity of TEE is reduced for prosthetic valves, it remains >80% due to the higher frequency ultrasound beam providing better resolution of the cardiac valves. TEE can help determine the extent of vegetations. TTE echo is better for evaluation of the tricuspid valve in comparison to other valves due to its close proximity to the chest wall.

1. Biswas A, Yassin MH. Comparison between transthoracic and transesophageal echocardiogram in the diagnosis of endocarditis: a retrospective analysis. Int J Crit Illn Inj Sci. 2015;5(2):130-131.

2. Ryan EW, Bolger AF. Transesophageal echocardiography (TEE) in the evaluation of infective endocarditis. Cardiol Clin. 2000;18(4):773-787.

3. Sekar P, Johnson JR, Thurn JR, et al. Comparative sensitivity of transthoracic and transesophageal echocardiography in diagnosis of infective endocarditis among veterans with Staphylococcus aureus bacteremia. Open Forum Infect Dis. 2017;4(2):ofx035.

2. Correct Answer: A. TTE with contrast study is better at detecting a PFO as compared to evaluation with TEE.

Rationale/Critique: TTE has been shown to be more sensitive (>80%) for PFO detection when utilizing contrast when compared to TEE (<60%) with contrast. TEE usually requires some form of sedation, which can lead to decreased right atrial (RA) pressures as a result of decreased venous return. The decreased RA pressure in comparison to the left atrial pressure may prevent interatrial shunting through a PFO. A Valsalva maneuver helps to generate an increase in RA pressure, which may favor right-to-left shunting through the PFO. However, this may not hold true in patients with markedly elevated left atrial pressure. Axial resolution is improved with higher frequency ultrasound waves. Higher frequency waves do not penetrate tissue as deeply as lower frequency waves because of attenuation. The TEE probe is positioned closer to the interatrial septum, allowing for the use of higher frequencies. See Figure 12.1.

1. Armstrong WF, Ryan T. Left and right atrium, and right ventricle. In: Armstrong WF, Ryan T, eds. Feigenbaum’s Echocardiography. 8th ed. Wolters Kluwer; 2019:158-193.

2. Thanigaraj S, Valika A, Zajarias A, Lasala JM, Perez JE. Comparison of transthoracic versus transesophageal echocardiography for detection of right-to-left atrial shunting using agitated saline contrast. Am J Cardiol. 2005;96(7):1007-1010.

3. Yue L, Zhai YN, Wei LQ. Which technique is better for detection of right-to-left shunt in patients with patent foramen ovale: comparing contrast transthoracic echocardiography with contrast transesophageal echocardiography. Echocardiography. 2014;31(9):1050-1055.

3. Correct Answer: B. TEE is more likely to identify an intrapulmonary shunt as the pulmonary veins are imaged in greater detail.

Rationale: An intrapulmonary shunt is more likely to be identified with a TEE compared to TTE. TTE typically only allows visualization of the pulmonary veins as they empty into the left atrium. On the other hand, portions of the pulmonary veins can be imaged during TEE, allowing visualization of contrast within the veins as a result of intrapulmonary shunt. This can be especially helpful when there is a concomitant interatrial shunt. On TTE, the contrast will be noted within the left atria and make it difficult to determine if contrast is a result of an atrial or an intrapulmonary shunt because of the inability to identify the extent of the pulmonary veins. However, with direct visualization of the pulmonary veins on TEE, the contrast can be seen returning from the lungs.

1. Abushora MY, Bhatia N, Alnabki Z, Shenoy M, Alshaher M, Stoddard MF. Intrapulmonary shunt is a potentially unrecognized cause of ischemic stroke and transient ischemic attack. J Am Soc Echocardiogr. 2013;26(7):683-690.

2. Rollan MJ, Munoz AC, Perez T, Bratos JL. Value of contrast echocardiography for the diagnosis of hepatopulmonary syndrome. Eur J Echocardiogr. 2007;8(5):408-410.

4. Correct Answer: C. RV longitudinal strain by TTE and TEE is similar.

Rationale: With TTE the RV s′ value is obtained from the apical four-chamber view. This allows the s′ to be measured at the lateral tricuspid annulus. The tissue movement during systole is toward the ultrasound probe and this provides good alignment for tissue Doppler. Tissue Doppler is angle dependent, and anytime there is an angle between the tissue movement and the ultrasound beam, there will be underestimation of the value. In the TEE midesophageal four-chamber view, the ultrasound beam does not line up well with the movement of the lateral tricuspid annulus. When using another view such as the modified transgastric RV inflow view with TEE, which provides the best ultrasound beam to tissue movement alignment, the inferior portion of the tricuspid valve is being measured. The s′ values in any of the comparisons are not interchangeable. Strain by speckle tracking is angle independent, and RV strain by TTE and TEE is similar. Cardiac magnetic resonance imaging (MRI) is the gold standard for RV measurements.

1. Gebhardt BR, Asher S, Maslow A. The limitations of using transthoracic echocardiographic-derived normative values for grading intraoperative transesophageal echocardiography examinations of the right ventricle: are they really interchangeable? J Cardiothorac Vasc Anesth. 2020;34(5):1260-1262.

2. Kurt M, Tanboga IH, Isik T, et al. Comparison of transthoracic and transesophageal 2-dimensional speckle tracking echocardiography. J Cardiothorac Vasc Anesth. 2012;26(1):26-31.

3. Roberts SM, Klick J, Fischl A, King TS, Cios TJ. A comparison of transesophageal to transthoracic echocardiographic measures of right ventricular function. J Cardiothorac Vasc Anesth. 2020;34(5):1252-1259.

5. Correct Answer: A. Tamponade is more likely to be seen if TEE is used vs TTE for this patient.

Rationale: Overall, TTE is considered the gold standard for evaluation of tamponade; however, postsurgical changes from an open chest procedure make TTE difficult due to ultrasound beam interference. This can lead to poor differentiation between tissue and hematoma as well as other structures. Patients who have undergone an open cardiac procedure are at risk for pericardial tamponade. In this population, TEE is more sensitive as compared to TTE for identifying pericardial tamponade. The poor windows generated from the postsurgical chest are avoided, with TEE leading to better image acquisition. Unlike typical tamponade, which involves larger portions of the pericardium, postsurgical tamponade can be loculated. If there is concern for pericardial tamponade and echo imaging is inconclusive, then CT imaging would be warranted.

1. Imren Y, Tasoglu I, Oktar GL, et al. The importance of transesophageal echocardiography in diagnosis of pericardial tamponade after cardiac surgery. J Card Surg. 2008;23(5):450-453.

2. Kronzon I, Tunick PA, Freedberg RS. Transesophageal echocardiography in pericardial disease and tamponade. Echocardiography. 1994;11(5):493-505.

6. Correct Answer: C. Evaluation of the abdominal aorta to determine the extent of the dissection

Rationale: TEE can evaluate for aortic dissections and the associated findings such as aortic regurgitation, wall motion abnormalities, and pericardial effusion. When a dissection is present, TEE may demonstrate aortic regurgitation, wall motion abnormalities, and pericardial effusion. Due to the close positioning of the esophagus and aorta, TEE can utilize higher frequency imaging for better resolution as compared to TTE. Sensitivity of imaging modalities in aortic dissection: TEE 99%, MRI and CT 95% to 98%. See Figure 12.2.

1. Baliga RR, Nienaber CA, Bossone E, et al. The role of imaging in aortic dissection and related syndromes. JACC Cardiovasc Imaging. 2014;7(4):406-424.

2. Banning AP, Masani ND, Ikram S, Fraser AG, Hall RJ. Transoesophageal echocardiography as the sole diagnostic investigation in patients with suspected thoracic aortic dissection. Br Heart J. 1994;72(5):461-465.

3. Evangelista A, Flachskampf FA, Erbel R, et al. Echocardiography in aortic diseases: EAE recommendations for clinical practice. Eur J Echocardiogr. 2010;11(8):645-658.

4. Garcia-Cortes RS, Rao PK, Quader N. Transesophageal echocardiography. In: Quader N, Makan M, Perez J, eds. The Washington Manual of Echocardiography. 2nd ed. Wolters Kluwer; 2017:294-324.

5. Schiller NB, Ren X, Ristow B. Echocardiograpic evaluation of the thoracic and proximal abdominal aorta. In: Manning WJ, Yeon SB, eds. Uptodate. Uptodate; Accessed on November 11, 2019.

7. Correct Answer: B. TTE can be used during chest compressions.

Rationale: Utilizing echo for evaluation of cardiac arrest patients is helpful in identifying reversible causes and may help direct therapy. During pseudo-PEA, echo can help visualize cardiac contraction even if no pulse is palpable as a result of low cardiac output. Absence of contraction is seen with true PEA. TTE has been shown to increase the time during pulse checks beyond 10 sec. This does not decrease TTE utility in this scenario. However, periods of TTE during pulse checks should be monitored to remain less than 10 sec. Many TTE views are not possible and image acquisition can be difficult during chest compressions. However, using the subcostal view can allow for imaging during compressions.

1. Long B, Alerhand S, Maliel K, Koyfman A. Echocardiography in cardiac arrest: an emergency medicine review. Am J Emerg Med. 2018;36(3):488-493.

2. Price S, Uddin S, Quinn T. Echocardiography in cardiac arrest. Curr Opin Crit Care. 2010;16(3):211-215.

8. Correct Answer: A. TEE provides better 2D imaging of the mitral valve.

Rationale: The close proximity of the TEE probe to the mitral valve allows for better 2D imaging. This makes TEE ideal for localizing specific structural abnormalities that can help guide surgical correction. TEE with color flow can be used in multiple sector angles with better resolution to evaluate the regurgitant jet with more precision as compared to TTE. TTE is better for left atrial dimensions due to the ability to capture the entire atrium. Due to the close positioning of the TEE probe to the left atrium, it generally gets foreshortened. For this same reason TTE is better for measuring maximal mitral regurgitation jet area to left atrial area ratio. Pulmonary vein flow is better evaluated with TEE.

1. Foster E. Transesophageal echocardiography in the evaluation of mitral valve disease. In: Manning WJ, Gassch WH, eds. UpTo-Date. UpToDate; 2019.

9. Correct Answer: B. TEE is better than TTE for capturing different areas of the LAA.

Rationale: Due to the close proximity of the esophagus to the LAA, TEE can utilize higher frequency ultrasound to visualize the structure. Different areas of the LAA can be visualized by manipulating the sector angle and probe positioning with TEE. This all contributes to TEE being better able to evaluate the LAA. Echo contrast has been shown to improve imaging of the LAA with TEE. This can be useful when there are obstacles to optimal LAA evaluation such as spontaneous echo contrast and pectinate muscle interference. TEE is considered superior to TTE for LAA evaluation. LAA velocity <40 cm/s indicates an increased risk of stroke. See Figure 12.3.

1. Abdelmoneim SS, Mulvagh SL. Techniques to improve left atrial appendage imaging. J Atr Fibrillation. 2014;7(1):1059.

2. Beigel R, Wunderlich NC, Ho SY, Arsanjani R, Siegel RJ. The left atrial appendage: anatomy, function, and noninvasive evaluation. JACC Cardiovasc Imaging. 2014;7(12):1251-1265.

3. Armstrong WF, Ryan T. Mitral valve disease. In: Feigenbaum H, Armstrong WF, Ryan T, eds. Feigenbaum’s Echocardiography. 6th ed. Wolters Kluwer; 2004:306-340.