A left Atrial Mass After COVID-19 and Cardiac Surgery.

A three-month-old girl (weight: 4.3 kg; height: 55 cm) with trisomy-21 was taken to the operating room for repair of an atrioventricular canal defect. The transthoracic echocardiogram reported situs solitus; atrioventricular and ventriculoarterial concordant connections; normal systemic and pulmonary venous drainage; a 3.9-mm primum defect with a left-to-right shunt; a large size (26 mm) inlet ventricular septal defect with left-to-right shunt; a large patent ductus arteriosus with a bidirectional shunt; and good biventricular function with a normal-sized coronary sinus. The baby previously was hospitalized for Coronavirus disease 2019 (COVID-19) seven weeks before surgery. A deep venous thrombosis was identified ten days before surgery, which initially was treated with intravenous heparin and subsequently transitioned to low-molecular-weight heparin. The transesophageal echocardiography before cardiopulmonary bypass confirmed the previous findings (Fig 1 , Video 1). The intracardiac repair was performed on cardiopulmonary bypass, and the left heart chambers were vented for better visualization of the cardiac structures, with a left atrial vent that was inserted through the foramen ovale. After separation from cardiopulmonary bypass, an echo-dense mass was visualized in the left atrium (Fig 2, Fig 3 ; Videos 2 and 3). The peak and mean pressure gradients across the mitral valve were assessed by a pulse-wave Doppler (Fig 4 ). What is the diagnosis?

Fig 1

Midesophageal four-chamber two-dimensional and color Doppler blood flow images by transesophageal echocardiography displaying the anatomy.

Fig 2

Midesophageal four-chamber two-dimensional and color Doppler blood flow images by transesophageal echocardiography showing a mass in the left atrium.

Fig 3

Midesophageal aortic long-axis view by transesophageal echocardiography demonstrating the left atrial mass.

Fig 4

Midesophageal four-chamber view by transesophageal echocardiography showing the pulse-wave Doppler signal across the left ventricular inflow.

Diagnosis: Left Atrial Appendage Inversion

In view of the baby's medical history of recovery from COVID-19 infection and deep vein thrombosis, the dilemma was that this mass might be a thrombus with the potential for systemic embolization. If that were the diagnosis, it meant reheparinization, reinstitution of cardiopulmonary bypass, and reversing the atrial septation, for inspecting the left atrial chamber under cardioplegic arrest would have been required.

The authors previously reported an invagination of a left atrial appendage probably due to a left atrial vent that was inserted through a patent foramen ovale during the repair of a child with Tetralogy of Fallot. With this in mind, as well as the finding that the newly encountered left atrial opacity had the same echo density as the surrounding cardiac tissues, a careful examination of the appendage with minimal disturbance to the hemodynamic parameters was done. This revealed an inversion of the left atrial appendage and it was restored immediately to its normal configuration. The transesophageal echocardiogram after this maneuver showed the disappearance of the mass. However, the left atrial appendage appeared to be collapsed, with the imaging of an echo-dense “coumadin ridge.”

The alternative diagnosis was a left atrial thrombus that often is a major source of concern, especially after cardiac surgery that may necessitate immediate corrective measures. The features of a left atrial thrombus may include: a relatively well-defined border; mobility throughout the cardiac cycle; demonstrable in more than one echocardiographic view; displays a constant and reproducible position in the left atrial cavity; and demonstrates a surface attachment to the left atrial wall in at least one echocardiographic view, with an echo density that is different from that of the adjoining cardiac structures. In contrast, a left atrial inversion displays an echo density that is similar to that of the surrounding cardiac structures. Left atrial inversion may be seen in the midesophageal four-chamber view as a mass just superior to the mitral valve but inferior to the pulmonary veins.

An iatrogenic inversion of the left atrial appendage may occur during open cardiac surgery as a result of excessive negative pressure applied to a left ventricular vent. It also may occur if digital insertion into the left atrial chamber is used to help dislodge trapped air as part of deairing maneuvers at the time of release of the aortic crossclamp. An iatrogenic inversion of the left atrial appendage, if not restored to its normal configuration, may result in necrosis and rupture, leading to a pericardial tamponade. In addition, an unresolved inversion may pose a postoperative diagnostic conundrum.