Discussion:
Discovery of a left atrial mass intraoperatively raises a suspicion of a clot, tumor or vegetation. Suction force produced by left ventricular assist device, can cause deformity of the left atrial appendage causing inversion. In case of severe heart failure, LVAD is activated and flows are gradually increased as the cardio-pulmonary bypass flows are reduced, in a bid to transition from full CPB to assisted flows with the LVAD. Increased suction force from the LVAD, especially in presence of low blood volume in the left ventricular chamber can pull blood from the left atria across the mitral valve and can result in inversion of the left atrial appendage. It is also possible that the appendage may invert during the de-airing manoeuvres11Bouzas‐Mosquera A, Alvarez‐García N, Cuenca‐Castillo JJ. Inverted left atrial appendage. Heart 2008;94:1064.. On TEE, it may present as a “crooked finger” or with a tongue-like appearance22Leong MC, Latiff HA, Hew CC, Mazlan SL, Osman H. Inverted left atrial appendage masquerading as a cardiac mass. Echocardiography 2013;30:E33‐5.. Apart from causing confusion in the diagnosis, it can cause mitral valve obstruction and impaired ventricular filling33Molaei A, Tabib A, Meraji M, Shemirani RH. Inverted left atrial appendage: A cause of left ventricularinflow obstruction. Iran Cardiovasc Res J 2010;4:139‐41. and necrosis and rupture of the left atrial wall. It can also lead to distortion of the pulmonary veins causing pulmonary congestion and subsequent right ventricular failure, especially in cases of borderline right ventricular function44Gattani R, Ekanem E, Shea J, Zhao Q, Singh R, Liam RP. Left atrial appendage inversion presenting as acute right ventricular failure after left ventricular assist device implantation. Journal of the American College of Cardiology. 2020 Mar;75(11):2389. Patients with dilated cardiomyopathy have functional mitral regurgitation and subsequent LA dilation with enlarged appendage and thus are susceptible to appendage inversion. Inability to identify the mass as an inverted LAA can result in unnecessary return to CPB, surgical intervention, and additional ischemia time. Regular pre-operative trans-esophageal echocardiographic assessment for patients undergoing LVAD implantation includes assessment of left atrial appendage for clots, especially in presence of severe MR and atrial fibrillation55Flores AS, Essandoh M, Yerington GC, Bhatt AM, Iyer MH, Perez W, et al. Echocardiographic assessment for ventricular assist device placement. Journal of Thoracic Disease. 2015 Dec 17;7(12):2139–50.. It is essential to have a high index of suspicion for an inverted LAA, especially when a new mass appears post-surgery. Comparison with pre-operative images will help clinch the diagnosis especially with the knowledge that the mass is homogenous and arises from the anterolateral wall of the atrium just superior to the mitral valve and inferior to the pulmonary veins. Absence of left atrial appendage when seen in the mid-esophageal two chamber view and mid esophageal left atrial appendage view along with typical shape of the mass with a broad base and highly mobile tip is highly suspicious of appendage inversion66Leong MC, Latiff HA, Hew CC, Mazlan SL, Osman H. Inverted left atrial appendage masquerading as a cardiac mass. Echocardiography. 2013 Feb;30(2):E33–5.. Inverted appendage generally everts spontaneously with fluid loading of LV (Trendelenberg manoeuvre or Valsalva manoeuvre) or by transiently reducing LVAD flows. Other methods to correct it include digital manipulation, or using forceps77Chikwe J, Fischer GW, Adams DH. Inverted left atrial appendage. J Am Coll Cardiol 2009;54:e7.. Rarely, LA appendage ligation might be required to prevent re-inversion.
Intra-operative TEE is thus an invaluable tool to detect an inverted LAA and differentiate it from other potentially dangerous diagnosis like left atrial clot, which would have mandated unnecessary reinstitution of cardiopulmonary bypass and re-surgery.