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.