A Case of Two Pulmonary Arteries in a Child with Sinus Venosus Atrial Septal Defect

To the Editor, Echocardiographic artefacts are commonly encountered intraoperatively and often interests or confuses the practitioner, depending on the scenario. We encountered a very convincing artefact showing two pulmonary arteries in a child with sinus venosus atrial septal defect (ASD) and partial anomalous pulmonary venous connection (PAPVC), posted for surgical closure of the ASD and PAPVC rerouting. During the post operative transesophageal echocardiographic examination (TEE), in the mid-esophageal aortic valve short axis view, two vessels were seen concentrically winding around the aortic valve in short axis. Both colour flow Doppler and pulse wave Doppler demonstrated flow in the said vessel [Figure 1]. Though the Doppler signals are expected to be weaker in the artefact, our artefact had stronger Doppler signals than the real image unlike previously reported cases [Figure 1c and d].[1] The structure looked and moved exactly like the pulmonary artery located immediately above it. Since the structure was neither seen pre-operatively in TEE nor intraoperatively, it was sure to be an artefact, most likely a mirror image artefact.Figure 1: (a) Showing the mid-esophageal aortic valve short axis view, rotated to focus on the right ventricle, showing aortic valve (Red arrow), pulmonary artery (Blue arrow) and the mirror artefact of the pulmonary artery (Green arrow). (b) Shows the color Doppler evaluation of the pulmonary artery. Both the real image and the mirror artefact shows color flow. (c) Shows the pulse wave Doppler evaluation of the pulmonary artery. (d) Shows the pulse wave Doppler evaluation of the mirror artefact. (e) Schematic image demonstrating the physics behind mirror image artefacts. The blue arrows depict the usual pattern of reflection of ultrasound signals and the purple arrows depict the pattern of ultrasound reflection, in presence of a reflector. Purple dashed lines denote the extrapolation of reflected waves by the transducer, leading to formation of the mirror imageWhen a displayed image conveys incorrect information about a true anatomy, they are called echogenic artefacts.[2] It can lead to misdiagnosis and unnecessary interventions. Mirror image artefact is one such echogenic artefact where a highly reflective surface reflects the ultrasound beam to the object of interest and the object reflects the waves back into the reflective surface before returning to the ultrasound transducer, leading to the formation of another image that is often deeper to the actual structure [Figure 1e].[2] The pattern of reflection and the strength of signals returning to the transducer might be responsible for deciding the intensity of the image formed. This could explain the stronger pulse wave signals from our artefact, in comparison to the real image. The ascending aorta or the ASD patch might have acted as a reflector in our case. The mirror images are known to show both color Doppler signal and pulse wave Doppler signal characteristics of the original structure.[1] In a congenital heart disease patient, presence of such convincing artefacts can have an implication on decision making and unnecessary interventions, though it was fortunately not so in our case [Video]. {"href":"Single Video Player","role":"media-player-id","content-type":"play-in-place","position":"float","orientation":"portrait","label":"Video 1","caption":"","object-id":[{"pub-id-type":"doi","id":""},{"pub-id-type":"other","content-type":"media-stream-id","id":"1_ucnlju15"},{"pub-id-type":"other","content-type":"media-source","id":"Kaltura"}]} Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.