Trick of the Eye or Trick of the Heart?

A 76-year-old woman with myxomatous changes of the mitral valve and severe mitral regurgitation underwent an elective mitral valve repair and coronary artery bypass grafting. The intraoperative course was complicated by an inferior vena cava tear and coagulopathy requiring return to the operating room on postoperative day 1 to rule out a surgical cause of ongoing bleeding. A transthoracic echocardiogram (TTE) was performed on postoperative day 6 (Video 1). An 88-year-old-man with severe aortic valve stenosis and atrial fibrillation had his anticoagulation discontinued after recurrent episodes of lower GI bleeding. He had a cardiac CT scan performed as part of a preoperative transcatheter aortic valve implantation (TAVI) workup. There were concerning findings on the CT scan, which prompted admission to hospital and a subsequent TTE (Video 2). Question: Based on the presented TTE clips, where is the abnormality in each clip located, and what is the most likely differential diagnosis? Answer: Patient 1: TTE demonstrated a possible mobile mass in the left atrium (LA), likely originating from the right upper pulmonary vein. This was further investigated with a cardiac CT scan (Fig 1), which revealed bilateral moderate-sized pleural effusions and atelectasis, but no evidence of a LA or pulmonary vein thrombus. Patient 2: The CT scan revealed a lobulated filling defect within the LA extending to the LA appendage and measuring 5.2 cm × 2.7 cm (Fig 2). Subsequent TTE demonstrated a mobile LA mass located in the inferior-posterior portion of the LA and extending into the LA appendage, consistent with an LA thrombus. The absence of LA and LA appendage filling defect on cardiac CT scan (Fig 1) ruled out an intracardiac thrombus such that the suspicious finding seen on TTE was most likely consistent with an imaging artifact. No further investigation or treatment was required. Anticoagulation was initiated, and the patient (who remained asymptomatic) was discharged home with a follow-up TTE scheduled in 1 month’s time. Artifacts are common and an inherent limitation of US-based diagnostic modalities such as echocardiography, often resulting in apparent distortions of normal anatomy, as exemplified herein (patient 1). Practitioners must understand how artifacts are generated and, most importantly, how to proceed when faced with a potential artifact. Misinterpreting artifacts as pathologic entities can lead to inappropriate patient interventions, and misreading pathologic findings as artifacts can prevent initiation of proper and timely management. Common imaging artifacts and their respective mechanisms have been previously described1Bertrand P.B. Levine R.A. Isselbacher E.M. Vandervoort P.M. Fact or artifact in two-dimensional echocardiography: avoiding misdiagnosis and missed diagnosis.J Am Soc Echocardiogr. 2016; 29: 381-391Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar, 2Le H.T. Hangiandreou N. Timmerman R. et al.Imaging artifacts in echocardiography.Anesth Analg. 2016; 122: 633-646Crossref PubMed Scopus (23) Google Scholar, 3Quien M.M. Saric M. Ultrasound imaging artifacts: how to recognize them and how to avoid them.Echocardiography. 2018; 35: 1388-1401Crossref PubMed Scopus (26) Google Scholar and can be broadly classified into two categories: (1) those arising from violating built-in assumptions within the US imaging system and (2) those arising from interference from external devices. Side-lobe and beam-width artifacts are generated when the assumption that echoes are only generated from reflectors within the main US beam is violated.3Quien M.M. Saric M. Ultrasound imaging artifacts: how to recognize them and how to avoid them.Echocardiography. 2018; 35: 1388-1401Crossref PubMed Scopus (26) Google Scholar A US beam has an hourglass appearance as it travels from the transducer. The beam remains the same width until it narrows toward the focal zone and then increasingly diverges beyond the focal zone1Bertrand P.B. Levine R.A. Isselbacher E.M. Vandervoort P.M. Fact or artifact in two-dimensional echocardiography: avoiding misdiagnosis and missed diagnosis.J Am Soc Echocardiogr. 2016; 29: 381-391Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar,3Quien M.M. Saric M. Ultrasound imaging artifacts: how to recognize them and how to avoid them.Echocardiography. 2018; 35: 1388-1401Crossref PubMed Scopus (26) Google Scholar (Fig 3). However, echogenic objects that reside where the beam diverges can be interpreted as originating from the focal zone, creating a beam-width artifact. Similarly, a side-lobe artifact is produced when the small amount of energy emitted from the side of the beam hits a strong reflector within these side lobes and is interpreted as originating from the central beam.3Quien M.M. Saric M. Ultrasound imaging artifacts: how to recognize them and how to avoid them.Echocardiography. 2018; 35: 1388-1401Crossref PubMed Scopus (26) Google Scholar In practice, echocardiographic beam-width and side-lobe artifacts are commonly produced from highly reflective annular or prosthetic interfaces and can be mistaken for thrombi or vegetations.1Bertrand P.B. Levine R.A. Isselbacher E.M. Vandervoort P.M. Fact or artifact in two-dimensional echocardiography: avoiding misdiagnosis and missed diagnosis.J Am Soc Echocardiogr. 2016; 29: 381-391Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar,4Kyavar M. Sadeghpour A. Alizadehasl A. Salehi N. Thrombosis on implanted device for atrial septal defect closure or echocardiographic beam width artifact? A diagnostic enigma.Int J Cardiovasc Imaging. 2012; 28: 1851-1852Crossref PubMed Scopus (5) Google Scholar Prior reports have demonstrated that beam-width artifacts have created the appearance of a strong reflector within the LA, which can be mistaken for migration of a pulmonary artery catheter or pacemaker lead into the LA.5Skubas N. Brown N.I. Mishra R. Diagnostic dilemma: a pacemaker lead inside the left atrium or an echocardiographic beam width artifact?.Anesth Analg. 2006; 102: 1043-1044Crossref PubMed Scopus (9) Google Scholar In the case of patient 1, we speculate that the observed artifact resulted from an interaction between the pleural effusion and the atelectatic lung, as follows: a pleural effusion appears as an anechoic space on US, and the atelectatic lung becomes comparatively hyperechoic and acts as a strong reflector located outside of the US beam focal zone, which in turn is picked up by the weak US beam side lobe and interpreted as occurring within the main US beam over the LA. Accordingly, Karabinis et al6Karabinis A. Saranteas T. Karakitsos D. et al.The ‘cardiac-lung mass’ artifact: an echocardiographic sign of lung atelectasis and/or pleural effusion.Crit Care. 2008; 12: R122Crossref PubMed Scopus (18) Google Scholar described a “cardiac-lung mass” artifact that serves as an example of how cardiac artifacts are generated from the interaction between the US beam and adjacent parenchymal lung disease.6Karabinis A. Saranteas T. Karakitsos D. et al.The ‘cardiac-lung mass’ artifact: an echocardiographic sign of lung atelectasis and/or pleural effusion.Crit Care. 2008; 12: R122Crossref PubMed Scopus (18) Google Scholar These investigators reported on an intracardiac artifact only visible in apical views in 17 of 205 patients with atelectasis or pleural effusions (11 within left cardiac chamber; 6 within right cardiac chamber). In all cases, atelectasis or pleural effusions were located adjacent to the heart, and in some cases the cardiac artifact displayed respiratory variation on M-mode. The artifact resolved with resolution of lung pathology. The authors speculate this cardiac-lung mass artifact is attributable to beam-width or mirror image artifact generated by abnormalities in the lung parenchyma.6Karabinis A. Saranteas T. Karakitsos D. et al.The ‘cardiac-lung mass’ artifact: an echocardiographic sign of lung atelectasis and/or pleural effusion.Crit Care. 2008; 12: R122Crossref PubMed Scopus (18) Google Scholar The artifact in patient 1 resided in the LA by the right upper pulmonary vein. The “cardiac-mass lung artifact” described by Karabinis et al6Karabinis A. Saranteas T. Karakitsos D. et al.The ‘cardiac-lung mass’ artifact: an echocardiographic sign of lung atelectasis and/or pleural effusion.Crit Care. 2008; 12: R122Crossref PubMed Scopus (18) Google Scholar appeared as an echogenic structure at the level of the mitral valve with a less echogenic, mobile structure projecting toward the LA. The addition of M-mode in the patient would have improved temporal resolution and potentially displayed respiratory variation similar to that demonstrated by Karabinis et al6Karabinis A. Saranteas T. Karakitsos D. et al.The ‘cardiac-lung mass’ artifact: an echocardiographic sign of lung atelectasis and/or pleural effusion.Crit Care. 2008; 12: R122Crossref PubMed Scopus (18) Google Scholar if indeed the observed artifact was originating from adjacent lung parenchymal disease. Application of color Doppler also may have revealed flow through the artifact that would not be seen with a true mass. Differentiating artifacts from true anatomy can be challenging, but various strategies have been described. An important concept that holds true to all types of artifacts is to image the same structure through different acoustic windows and with different angles because artifacts are not typically reproducible in multiple echocardiographic planes.2Le H.T. Hangiandreou N. Timmerman R. et al.Imaging artifacts in echocardiography.Anesth Analg. 2016; 122: 633-646Crossref PubMed Scopus (23) Google Scholar, 3Quien M.M. Saric M. Ultrasound imaging artifacts: how to recognize them and how to avoid them.Echocardiography. 2018; 35: 1388-1401Crossref PubMed Scopus (26) Google Scholar, 4Kyavar M. Sadeghpour A. Alizadehasl A. Salehi N. Thrombosis on implanted device for atrial septal defect closure or echocardiographic beam width artifact? A diagnostic enigma.Int J Cardiovasc Imaging. 2012; 28: 1851-1852Crossref PubMed Scopus (5) Google Scholar, 5Skubas N. Brown N.I. Mishra R. Diagnostic dilemma: a pacemaker lead inside the left atrium or an echocardiographic beam width artifact?.Anesth Analg. 2006; 102: 1043-1044Crossref PubMed Scopus (9) Google Scholar Artifacts also do not respect normal anatomic boundaries.7Markan S. Haider N. Novalija J. Iqbal Z. Gandhi S.D. Pagel P.S. A mobile threadlike structure in the left atrium: cor triatriatum, artifact, or thrombus?.J Cardiothorac Vasc Anesth. 2009; 23: 566-568Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar Minimizing the gain settings may help decrease strong reflections from weaker lobes, thereby reducing side-lobe artifacts,3Quien M.M. Saric M. Ultrasound imaging artifacts: how to recognize them and how to avoid them.Echocardiography. 2018; 35: 1388-1401Crossref PubMed Scopus (26) Google Scholar,5Skubas N. Brown N.I. Mishra R. Diagnostic dilemma: a pacemaker lead inside the left atrium or an echocardiographic beam width artifact?.Anesth Analg. 2006; 102: 1043-1044Crossref PubMed Scopus (9) Google Scholar which also can be mitigated with tissue harmonic imaging through improvement of image contrast.2Le H.T. Hangiandreou N. Timmerman R. et al.Imaging artifacts in echocardiography.Anesth Analg. 2016; 122: 633-646Crossref PubMed Scopus (23) Google Scholar, 3Quien M.M. Saric M. Ultrasound imaging artifacts: how to recognize them and how to avoid them.Echocardiography. 2018; 35: 1388-1401Crossref PubMed Scopus (26) Google Scholar, 4Kyavar M. Sadeghpour A. Alizadehasl A. Salehi N. Thrombosis on implanted device for atrial septal defect closure or echocardiographic beam width artifact? A diagnostic enigma.Int J Cardiovasc Imaging. 2012; 28: 1851-1852Crossref PubMed Scopus (5) Google Scholar Color Doppler is also useful,1Bertrand P.B. Levine R.A. Isselbacher E.M. Vandervoort P.M. Fact or artifact in two-dimensional echocardiography: avoiding misdiagnosis and missed diagnosis.J Am Soc Echocardiogr. 2016; 29: 381-391Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar because flow can be seen through the artifact but not through a true mass. Beam-width artifacts can be minimized with adjustment of the focal zone.1Bertrand P.B. Levine R.A. Isselbacher E.M. Vandervoort P.M. Fact or artifact in two-dimensional echocardiography: avoiding misdiagnosis and missed diagnosis.J Am Soc Echocardiogr. 2016; 29: 381-391Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar Finally, when in doubt, one should pursue additional imaging modalities3Quien M.M. Saric M. Ultrasound imaging artifacts: how to recognize them and how to avoid them.Echocardiography. 2018; 35: 1388-1401Crossref PubMed Scopus (26) Google Scholar, 4Kyavar M. Sadeghpour A. Alizadehasl A. Salehi N. Thrombosis on implanted device for atrial septal defect closure or echocardiographic beam width artifact? A diagnostic enigma.Int J Cardiovasc Imaging. 2012; 28: 1851-1852Crossref PubMed Scopus (5) Google Scholar, 5Skubas N. Brown N.I. Mishra R. Diagnostic dilemma: a pacemaker lead inside the left atrium or an echocardiographic beam width artifact?.Anesth Analg. 2006; 102: 1043-1044Crossref PubMed Scopus (9) Google Scholar,7Markan S. Haider N. Novalija J. Iqbal Z. Gandhi S.D. Pagel P.S. A mobile threadlike structure in the left atrium: cor triatriatum, artifact, or thrombus?.J Cardiothorac Vasc Anesth. 2009; 23: 566-568Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar (as was done in patient 1) to ensure no true pathologic abnormality is present that may jeopardize appropriate management (such as the real thrombus noted in patient 2). Video 3 highlights additional TTE images taken in patient 1 and patient 2 in an attempt to differentiate artifact from a true mass. See also the Narration Video for a detailed explanation of Videos 1-3. 1.Artifacts are produced when built-in assumptions within the US imaging system/equipment are violated or when there is external interference with the US beam. Recognizing how artifacts are generated can help avoid misdiagnosis and unnecessary testing.2.US artifacts are rarely visible in multiple acoustic planes and do not respect anatomic boundaries. Side-lobe and beam-width artifacts can be reduced or recognized by using tissue harmonic imaging, reducing gain, applying color Doppler, or adjusting the focal zone.3.Additional imaging modalities may be required to differentiate artifact from true anatomic or pathologic structures.4.Atelectasis associated with pleural effusions adjacent to cardiac structures are strong reflectors and can cause side-lobe or beam-width artifacts that may be misinterpreted as intracardiac masses. None declared. Author contributions: S. M. was involved in obtaining ethics approval, drafting and revising the manuscript, and approving the final version for publication. G. B. M. helped by drafting and critically revising the manuscript and approving the final version for publication. P. D. was involved in the care of the patients and helped by drafting and critically revising the manuscript and approving the final version for publication. R. A. helped by drafting and critically revising the manuscript and approving the final version for publication. Other contributions: CHEST worked with the authors to ensure that the Journal policies on patient consent to report information were met. Additional information: Videos for this case are available under "Supplementary Data." eyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiJlYTI0ZGJkN2RmOGExOTg1NzQ1YzNhNjZhYzhjM2NiMSIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjg4Mzg5NTQ4fQ.PyAmZbASw6FlXTwVCWzGxv9ZHkE1oP8mqm6PRI3lokR_qd6jhnMiYjtl7Tv3QnSz19w504ZhzLmYe3wGsrTZ0z1aqw1YWWMbEeorvwDmOlebnBxnBSZyfIAMskNk11KBd3K9_Xf-7TfGAj2_M78suitxCMuqG7esRenMVwYU8lKEop1sN9_tblfpWAqLJVKJGHzlWjpqVeRnwBH_gvMv73plEEbQxN6ZF_2sgjXCNh_CW7Jl6fi_vpR57Jx2VXMqQCPThgi4P9-xt50H-i6VsAOrhtc9JMuD0U7n3DhGHMgjlMIpPK3CQ9BhCc886zmXTXG4PAQhc6_5RHdbpudceQ Download .mp4 (13.39 MB) Help with .mp4 files Video 1Transthoracic echocardiogram apical four-chamber view of a 76-year-old woman on postoperative day 6 after a mitral valve repair and coronary artery bypass grafteyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiJlNjNlMWY1NzhiZTg1OGJlY2RiNjNhZDIyNjkzNGMzZiIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjg4Mzg5NTQ4fQ.ZLBn4Dl7MOIZJ3zEBBa-WkFtSMkcDpSNBHIMhJAdzkbZCxeezrkp8rY0kyy2JbtKidcVqoshTzIGlZfcFjw7IsGVXuS_AbJV3VE8ySh3Ts-DDglfTJBQnxRe-70PntXVOKaVlRU-5jRisw0sSIB4rBzdar52WP0DYYCDMBIaWHqLgOP7zWLHxU_3SZZxw1P3zKDDNu1iq7JGvQyWtlUhKmCJjOSmCYpq4H6C1qqriKheoKChG0NdaRv3FiRsin3STJfjcKzFJJZHMTGMIqxtIO0b6UELYBIe1803jmsJ2UjMIysypRZsdeMOAsNNa_jmQcTprCoB03LOgUmNzJpF3A Download .mp4 (13.35 MB) Help with .mp4 files Video 2Transthoracic echocardiogram apical four-chamber view of an 88-year-old man with aortic stenosis taken during the preoperative workup for a transcatheter aortic valve implantation (TAVI)eyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiJmOTA0Y2ZlYTY1NDYwZjllNWJjMjkyMTI3MmE3YzY1OSIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjg4Mzg5NTQ4fQ.gnxWpJATnjRO73S1RHkUuzftZ2xks-ZFAF5iN7brctn71F93OggZyxq2a1Peo68iAkN65f9ZNyFsEtF9Lw12bHINSoDv-siMyQtsTEMqcDcqkDZtE_ZIHSn7JRYpcN6D8YKYe6GJwIUk6Vjkj5_bNDLkNoPnqNvmVNe8eR-APjNiSgMpjVUMkfIRVMl_eg25l1olPxbC4vvRiX-3Gytcn8q76QVcCy2YZSQ2E1aGm_lb_jKvi1HekthIuQEedd4q-Km94FyqqA2B01cBEXkjbG6TEmvvLjDS6YcrAuuHXHyDoRXQOGam5w03zEiR-I2ty9xY8-fHmWixrgZUci9qdg Download .mp4 (77.17 MB) Help with .mp4 files Video 3The apical four-chamber TTE of the patient after the mitral valve repair reveals an echogenic structure in the LA, which may be a potential mass. Zooming in and focusing over the LA provides an increased resolution of this potential structure. The differential diagnosis includes whether this represents a true structure vs an artifact. The addition of color flow Doppler can be useful because color flow may move through an artifact but would not move through a true mass. Imaging through multiple acoustic windows is also useful because artifacts are not typically reproducible in multiple echocardiographic planes. Unfortunately, obtaining satisfactory acoustic windows can be a challenge, especially in postoperative patients, given the presence of surgical bandages and chest tubes, which can limit the acoustic windows, as is seen in this limited parasternal long axis view. However, note is made of a left-sided pleural effusion in the far field. As the probe is rotated, the parasternal short axis view of the left ventricle is obtained. Again, a pleural effusion can be seen in the far field as an anechoic space. Note the hyperechoic structure in the far field, likely representing atelectatic lung. We hypothesize that this hyperechoic tissue was picked up by the weak side lobe of the US beam in the apical four-chamber and appears as the hyperechoic mass seen within the LA. The apical four-chamber TTE of patient 2 demonstrates an echogenic mass in the LA, which appears to move with each cardiac systole. Echocardiographic contrast was used in this patient, which helps with visualization of the endocardial borders. There is potentially a filling defect seen in the LA from the presence of the clot. LA = left atrium; TTE = transthoracic echocardiogrameyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiJjNjYyNWU0MmI0ZjhkZmQ2MjI1Y2JjMGYwYjFjZTJmMSIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjg4Mzg5NTQ4fQ.hVz9kt-l7chB44nZRhWmDNj34XqGbLX37lMb-7uHmiRLbURK6MD9WMzODRqN3TmKe61wuB0tu51EGRUxQhoeDVrNtzWAZIQizjX0lKdBE3xpwiKRZAv6-cTzOIcaWcu-WqtkybzduZax4wei_4aroWqOYE0u0kP0SfOdng_Y8dgMWA3gtzfA3nr9TInCmlz5QEOwRejaDz9iD14cCAr2GoNkO_UiFtOk1jJJrwC8FP7ofQmAhSsMV5KgAwlNl69vvBTKMaGH3kqDRM1g2DxbA8Zw2K0BozSTsGqQ7pAz4fmjbNu2vlszWjXS3yUZFlt471hu_B31KkbG0pW5T462aQ Download .mp4 (74.41 MB) Help with .mp4 files Video 4